FRAUNHOFER-HHI AT A GLANCE

Public Research Institute (Shareholder: Fraunhofer-Gesellschaft zurFörderung der angewandten Forschung e.V.,Munich)Total staff at end of 2002: 274 employees

Areas of Research andDevelopment

Photonic Networks• Design, development and demonstration

of optical communication networks and subsystems (access, metro, and customer networks)

• Investigation and development of WDMand high-speed OTDM techniques forhigh capacity transmission and routing

• Exploration of high speed transmissionperformance of photonic networks

• Development of techniques for networkoperation and maintenance

• Development and fabrication of photonicdevices and integrated circuits (lasers,modulators, switches, optical amplifiers,filters, multiplexers and demultiplexers,signal regenerators, transceivers, receiverfrontends) based on InP, for passive components on SiO2/Si and polymers

• Development of new concepts for carrying IP traffic over WDM optical networks and wireless networks in an efficient manner (TransiNet)

• Switchable network design and testing

Mobile Broadband Systems• Development of space-time-receiver for

the uplink of mobile communication systems

• Design of downlink beamforming for CDMA-based mobile communication systems

• Teletraffic engineering for mobile communication systems

• Development of signal processing algorithms for OFDM/Multicarrier systems

• Development of sequences for CDMA applications and multiuser receiver

• Development of optical indoor transmis-sion networks for broadband WLAN

• Analysation of cooperative systems• MIMO channel measurements and

evaluation• Implementation of MIMO systems• Development of signal processing

algorithms for MIMO systems• Cooperative receiver and transmitter

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Electronic Imaging Technology for Multimedia• 3D image and video processing• Image and video coding• Image and video analysis and synthesis• Multimedia transmission (IP, mobile, DVB)• Hardware, software design and implemen-

tation of multimedia systems (video, audio, graphics), ASIC and IP design

• Immersive reproduction technologies• Multi-view capturing and reproduction

systems• Innovative 3D and mixed-reality displays• Perceptual user interfaces for mobile and

desktop applications• Human-machine interaction• MPEG-7 based image and video retrieval

systems• Mobile services for citizens• Sensing people technologies• Usability engineering

FRAUNHOFER INSTITUTE FORTELECOMMUNICATIONS,HEINRICH-HERTZ-INSTITUT

Einsteinufer 37, 10587 BerlinGermanyPhone: +49 (0)30 3 10 02-0Fax: +49 (0)30 3 10 02-213Email: info@hhi.fraunhofer.dehttp://www.hhi.fraunhofer.de

Executive Director:Prof. Dr. Joachim Hesse

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H E I N R I C H - H E R T Z - I N S T I T U T

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HHI REPORT 2002

Editorial coordination: Regina KiesewetterLanguage consultants:Ingeborg and Harvey HolmesLayout and typesetting:Zühlke Scholz & PartnerWerbeagentur, BerlinPrinting: Druckhaus Mitte, BerlinISSN 1435-1587

Reproduction is allowed only after permission from HHI and with a complete citation

Fraunhofer-Institut fürNachrichtentechnikHeinrich-Hertz-Institut Einsteinufer 37, 10587 Berlin

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TABLE OF CONTENTS

Fundamentals 9

Profile of the Institute 11Mission, Activities, Personnel and Financing 13Corporate Bodies 15Organisation and Contact Persons 16

R & D Activities 17R & D Fields 19Photonic Networks 19Mobile Broadband Systems 27Electronic Imaging Technology for Multimedia 30R & D Projects 39

Selected Contributions 47Research Initiative KomNet – Review and Final Results 49TransiNet – Innovative Transport Networks for the Broadband Internet 50All-Raman Amplified Links and EDFA Links with Switched Channels 51Monitoring of Transmission Impairments in Transparent WDM Networks using a Novel Control Modulation Technique 52WDM Transmission over Mixed Fibre Infrastructures 53Novel Slope-Compensating Optical Fibres Permits Capacity Increase for Future-Proof Long Haul WDM Systems 54Size and Cascadability Limits of SOA-based Burst Switching Nodes 55Novel All-Optical 3R Regenerator with Flexible Choice of Output Wavelength 56Modelling of PhaseCOMB Laser for Optical Clock Recovery 57160 to 40 Gb/s Demultiplexing Using a Self-Pulsating Laser-Based Clock Recovery Device 58Active Feedback Laser for Clock Recovery 59320 Gb/s Optical Sampling 60160 Gb/s Optical Clock Recovery using an Electro-Absorption Modulator 61Self-Cascaded Electro-Absorption Modulator for Improved Switching Performance 62Pulse Shaping for a 160 Gbit/s 3R Wavelength Converter 63Optical Intensity Filter for Noise Squeezing and Pulse Shaping 64Monolithic Mode-Locked Lasers for 160 Gb/s TDM Applications 65Multifunctional Optical Amplifying Microring Resonators for Integration in Photonic ICs 66All-Active Tapered 1.55 µm Index-Coupled InGaAsP BH-DFB Lasers With Continuously Chirped Grating 67Development of a Broadband InP-Based Mach-Zehnder Modulator with Electro-Optical Bandwidth Greater Than 40 GHz 68Nanotechnology for the Fabrication of Planar InGaAsP/InP Photonic Crystal Devices 6940 Gbit/s Balanced Photodetector Module Based on InP 7060 Gbit/s Photoreceiver Modules using InP OEICs for Direct Interfacing to a Demultiplexer Without a Bias-T 71Full On-Wafer Fabrication of a Bottom-Emitting 1.3 µm Buried Heterostructure Fabry-Perot Laser with Integrated 45° Reflector and Monitor Photodiode 72A New Approach to the Fabrication of Nanoscale Dot Arrays using Direct-Write Electron Beam Lithography 73Silicon-on-Insulator Photonic Crystal Structures for WDM Applications 74Intersubband Emitters Based on InP 75Wavelength Trimming of All-Polymer Athermal Arrayed Waveguide Multiplexers 76Measurements of the Capacity of MIMO Radio Systems in Indoor Environments 77Adaptive Signal Processing for Singular MIMO Channels 78MIMO with OFDM for Future 4G Wireless Systems 79Bandwidth-Efficient Non-Orthogonal Multicarrier Transmission Schemes 80Sum-Capacity Optimization of the MIMO Gaussian Multiple-Access Channel 81Duality Between Multiuser Beamforming Transmission in the Uplink and Downlink 82On Power Reduction Strategies for the Multiuser Downlink with Decentralized Receivers 83Joint Decoding and Channel-Estimation for Low-Complexity Space-Time Coding 84On a Distributed Multiantenna System using Cooperating Transmitters 85QS-CDMA versus W-CMDA: A Comparison of Air Interfaces for Wireless Communications 86

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TABLE OF CONTENTS

User-Friendly Retrieval of Video Content from Large Databases 87User-Tracking 3D Display for 3D TV and Internet Browsing 88A New Similarity Measure for Segmented Images 89Mobile Services for Citizens 90Innovative Man-Machine Interfaces 91Hybrid Display – Towards Natural Interaction in Mixed Reality 92Inside-Out Optical Tracking for Mixed-Reality PDAs 93Low-Cost Video Head Tracker for PC Applications 94Multiple View Traffic Surveillance with 3D Scene Reconstruction 95An MPEG-4 Video Codec ASIC for Mobile Applications 963D Model-Based Coding of Video using MPEG-4 97Multi-Standard Motion Compensated Image Format Converter HiCon32 98Processor Module based on StrongARM for Audio and Video Applications 99Virtual Team User Environments – a Mixed-Reality Approach to Immersive Tele-Collaboration 100Standardised Software Design for Multimedia Applications 101A Concept for 3D TV 102

Communications and Events 103Publications 105Reports 119Patent Applications 122Awards 124Acceptance of chairs 124Doctorate Theses 124Diploma Theses 124Graduate Theses 125Oral Presentations 126Lectures 128Workshops Organised 128Contributions to Exhibitions 129Committee Activities 129Exchange Program 130Cooperations 131Start up Companies 134

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FUNDAMENTALS

During 2002 the Heinrich-Hertz-Institut fürNachrichtentechnik Berlin GmbH (HHI) wasin a state of flux. On 30 April the two longserving managers, Professor Dr. Clemens Baackand Dr. Wolfgang Grunow, retired. They im-bued the HHI with their competence to be-come an important research centre fortelecommunications. On 12 July the share-holders changed too, when the FederalRepublic of Germany and the State of Berlintransferred the Institute to the “Fraunhofer-Gesellschaft zur Förderung der angewandtenForschung e.V.”, München (Fraunhofer Soci-ety for the Promotion of Applied Research,Munich) (FhG). For the legal transfer to theFhG the HHI GmbH was first of all convertedto the HHI für Nachrichtentechnik Berlin e.V.& Co. KG and then integrated into the FhG,with effect from 11 November 2002. Sincethen the HHI operates as the Fraunhofer-Institut für Nachrichtentechnik (FraunhoferInstitute for Telecommunications) with theadditional trading name Heinrich-Hertz-Institut.

The transition is proceeding smoothly. Tofulfil the most important criterion, namelythe strengthening of the earning capacity ofthe HHI, there remains a leeway to about2007. By then the HHI must increase its pro-portion of income from outside sources fromabout 60 % to 80 %.

A serious problem was and is the filling ofthe management position (now: Director ofthe Institute). The Fraunhofer Society andthe Technical University Berlin (TUB) haveagreed that the new Head of the Institutewill be appointed as a C4 Professor of Tele-communications at the TUB and at the sametime Director of the HHI. The procedure forthis appointment means that the head of thenew HHI Institute cannot take office till au-tumn 2003 at the earliest.

For the transitional period the new and oldshareholders have, in agreement with theBoard, engaged its former chairman, Profes-

sor Dr. Joachim Hesse, to manage the HHIfrom 1 May. Under his control the HHI is ap-plying itself mainly to enhancing its earningcapacity. In the foreground will be the rele-vance to industry of the three research areas.The HHI has in the mean time taken the fol-lowing steps to increase its earning power:

• It has modified its management structure.All important procedures relevant to busi-ness will be prepared by a committee con-sisting of the heads of department and theexecutives of important service areas of theHHI;

• It has ensured transparency of the recom-mendations or decisions by the executivecommittee via minutes and with follow-upinformation to all staff;

• It has decided budgeting and costing (oth-er income, establishment income) by bal-ancing performance across departments;

• It has introduced an investment shareoutto the departments based on their externalincome, after first deducting investmentfor maintenance and expansion of the ser-vice areas, as discussed by the executivecommittee;

• It has set up a department-oriented mar-keting system with central coordination;

• It has passed guidelines for its patent policy,for internal cooperation, for further train-ing and for the development of leaders.

These guidelines have stimulated researchin 2002. In that year the HHI had an autho-rised expenditure of ¤ 33.1 million, but theactual expenditure was around ¤ 30.7 mil-lion. The plan was that ¤ 18.4 million of thisshould be covered by income from paidthird party research projects, but because ofa delay in approving all the projects, thosethat were approved could only bring in ¤ 16million in 2002. On the whole this is a re-markable result in view of the increasingly dif-ficult market conditions. The table shows theindividual sources of third party income, to-gether with last year’s figures for comparison:

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The industry component was quite goodin terms of the old HHI GmbH guidelines,but the usual FhG standard is higher. Thereis a strategic deficit in the low EU quota. Anattempt to increase this is required, if onlybecause suitable R&D partners are the keyfor accessing European industry.

In 2002 the HHI has safeguarded its sup-port for R&D activities with 19 patent appli-cations (previous year: 22) and has docu-mented its scientific results in 242 publica-tions (previous year: 153). 22 lectures orseminars have been given by members of itsstaff at the cooperating universities, mainlyat the TUB (previous year: 17). The HHI alsoemployed on average 79 scientific assistants(previous year 80). 12 students have writtentheir theses on HHI topics (previous year: 18).Also, 4 of its employees received a doctorate(previous year: 2).

At the end of 2002 the HHI had 274 em-ployees (previous year: 272), of whom 155were scientists (previous year: 153). The HHIhas therefore maintained its personnel estab-lishment. The FhG has made a bindingpromise to take over this level of personnel.An amount of ¤ 6.6 million was invested(previous year: 6.8).

The HHI expresses its thanks to its previousshareholders, its Board and Science Councilfor a long period of good cooperation andactive support.

The HHI starts its first year within theFraunhofer Society with confidence.

Berlin, January 2003Joachim Hesse

2001 2002

Expenditure 29.5 30.7

Establishment income 14.0 14.7

Other income 15.5 18.4

Other income sources:

• Industry 3.1 3.6

• General business 0.9 1.1

• EU 0.4 0.9

• BMBF/BMWi 9.1 10.4

• State of Berlin 0.1 1.7

• DFG 0.8 0.7

• Other 1.1 –

Financial Overview ¤ (millions)

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Profile of the Institute

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Mission, Activities, Personnel andFinancing

Information technology provides the com-munication infrastructure of modern soci-eties. The ever expanding global network willgive virtually everybody access to immenseinformation resources, which opens the doorto the era of the knowledge based, or “infor-mation”, society.

The evolution of communication networkshas led to a huge, multi $100 billion market.Although we are currently witnessing a per-severing market downturn and a sometimesdramatic worldwide readjustment of industri-al capacities, the user demand for broadbandservices is still growing, and the roadmapsfor research and development existing in thisfield have not undergone greater revisionsapart from retarded forecasts for the intro-duction of the next technology generation.

The paramount task in information tech-nology is the development of a seamlessglobal network, which is structured into anoptical Core Network, high capacity fibre op-tics Metro Networks, and Access Networks inwhich the end users are connected via fibre(or, as an intermediate solution, over copperwire), wireless or broadband mobile. Thenetwork must provide the bandwidth need-ed for the subscriber to access all existingand future communication and informationservices with high quality and low latencyand, above all, at a low price.

HHI has taken an internationally recog-nised role in several key areas of informationtechnology: photonic networks, mobile broad-band systems, and electronic imaging tech-nology for multimedia. Its aim is both to ex-pand the fundamentals in these areas and todevelop new applications in close partner-ship with the industry.

In the research area of Photonic Networks,the ground is being laid for Terabit/s coreand regional backbone networks by ourwork on optical time-division (OTDM) andwavelength-division (WDM) multiplex tech-niques, methods for all-optical signal regen-eration, and ultra high speed fibre transmis-sion experiments up to 320 Gb/s as well asmeasurement methods. For metro and ac-cess networks, dynamically flexible architec-tures with optical switching in conjunctionwith WDM techniques are also under investi-gation. Network management and protocoladaptation play an increasing role in seam-less networks. Today, “fibre to the home”has become a very active R&D area aiming

at 100 to 1000 Mb/s subscriber lines, whilecustomer in-house networks with a fibre op-tic infrastructure and wireless access requireextremely cost-efficient solutions.

Our research and development work onphotonic devices focuses on the next genera-tion metro and core networks. Key compo-nents under development are uncooledsemiconductor lasers for direct 10 GHz mod-ulation and flip-chip mountable broadbandphotodiodes for transceivers to be used inthe 10G Ethernet; lasers for WDM networks,including ring lasers and associated filter ele-ments; picosecond pulse laser sources, fastelectro-optical modulators and demultiplexerswitches for OTDM networks; laser-based de-vices for optical 3R regenerators; and broad-band receiver front ends for 80 Gb/s and be-yond.

Optical crossconnects are becoming animportant alternative to electronic switchesfor handling the multi-Terabit/s data through-put at network nodes. Wavelength convert-ers based on semiconductor optical ampli-fiers have an important function in this appli-cation. Another group of components areplanar waveguide devices for the passive op-tical network using the SiO2/Si material sys-tem and optical polymers. Photonic bandgapstructures are an advanced concept for opti-cal elements and circuits, with great poten-tial for realising ultracompact passive and ac-tive devices in future photonic networks.

Mobile communication is at present stilllimited to narrowband applications, in con-trast to communication on the wired net-work. Because mobile networks, as an exten-sion of the fixed network or as (ad-hoc) clus-ters, are continually increasing in bothperformance and penetration, there is agrowing need for broadband mobile connec-tions. The challenge for research is to devel-op suitable system concepts and techniquesfor broadband mobile systems. To do this wemust reconsider the fundamentals of infor-mation and signal theory and show the feasi-bility of the new basic concepts in a demon-strator. This involves considerable effort toimprove coding schemes and algorithms, toestablish new technical principles, such assmart antenna systems for multiple-inputmultiple-output (MIMO) and space-divisionmultiplexing systems, and to drive the devel-opment of the standards. The HHI pursuesthese topics with projects in the area ofMobile Broadband Systems.

Data compression is needed to use thenetwork capacity economically, especially for

high-rate video services. It is necessary tocontinue research in this area and to developcompression methods with not only im-proved performance, but also with new func-tionalities, especially for interactive applica-tions. Furthermore, efficient network solu-tions using media codecs is of crucialimportance due to their susceptibility totransmission errors, especially for 3rd and 4th

generation mobile networks.Tele-Immersion is becoming increasingly

important. Therefore new methods for 3Dimage processing, 3D displays and man-ma-chine interaction must be developed. Thegoal is to enable the user to navigate andcommunicate in real and virtual worlds, andto use immersive services and applicationsover networks. The development of nextgeneration information systems, which willenable the user to efficiently archive, searchand retrieve data, is becoming increasinglyimportant. Intelligent and user-adaptive sys-tems will be needed to make it easy for theuser to identify and access visual information,both natural and synthetic. It is important topursue research on various aspects of usabili-ty engineering to develop applications andservices that are user-oriented and user-friendly. The HHI is working on these tasks inthe area of Electronic Imaging Technologyfor Multimedia.

At the end of the reporting year, the insti-tute had 274 employees, 155 of whom werescientific staff and 127 technical and admin-istrative staff. Of these, 127 positions were inthe research area Photonic Networks, 80 inthe research area Electronic Imaging Technol-ogy for Multimedia, 22 in the research areaMobile Broadband Systems, and 45 in cen-tral functions such as management, plan-ning, administration and workshops. At theend of the year there were also four post-graduate doctoral students, eight persons intraining, 79 student assistants and threeguest scientists working at the HHI.

In 2002 the overall budget amounted toEUR 30.7 million. The external funding repre-sented 59.9 % of the budget which included15.3 % from direct contracts with industry.Cooperation agreements were concludedwith the leading IT companies in Europe.HHI continues to be a member in the AlcatelResearch Partnership Program, under whichadvanced research projects in all-optical sig-nal processing, ultrahigh bit rate transmis-sion, semiconductor materials technology,and optical polymer devices are being car-ried out. The joint national project KomNet

(sponsored by BMBF and coordinated byHHI) was successfully concluded in April 2002.HHI has won several contracts in the succes-sor project Multi-Teranet which started inSeptember 2002 and is geared to the futuregeneration of optical core and broadbandmetro/access networks and their key compo-nents.

HHI has increased its engagement in stra-tegic partnerships with innovative SMEsworking on photonic components. Thesecompanies run collaborative R&D projects inthe areas of high end components for opticaltelecommunication networks, such as fastlasers, WDM sources, modulators, and detec-tor front ends. They also carry out system de-velopment and system testbed evaluation.HHI also serves these partners as a chip andwafer source for prototype series of new de-vices, thereby creating the opportunity forflexible and fast introduction to the market.Through these initiatives HHI has participat-ed in creating some 100 highly skilled work-ing positions in the Berlin area. In May 2002a joint R&D project sponsored by the Inno-vation Programme Berlin was launched todevelop development key components forthe 10G Ethernet with three Berlin basedstart-up-companies and HHI.

We have continued our policy of increas-ing public relations and marketing activities,including presentations of our research activ-ities at the technical exhibitions of the majorconferences (International Conference onOptical Fiber Communication (OFC), Euro-pean Conference on Optical Communication(ECOC), European Microwave Conference)and at prominent trade fairs (CeBIT,Hannover Messe, Laser Optics Berlin, etc.).

Last but not least, services in the areas oftesting and measurements, feasibility studies,design work, e-beam mask plate manufactur-ing, epitaxy wafer and semiconductor pro-cessing services, and others, have contrib-uted to our industrial relations.

HHI has further developed its quality man-agement system to give increased customerorientation, and ISO 9001 was again recerti-fied in November.

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Corporate Bodies

The corporate bodies of the HHI are theGeneral Meeting, the Supervisory Board, theManaging Directors and the Scientific-Tech-nical Committee. Due to the changing of theshareholder of the institute, the activities ofthe corporate bodies and committees havebeen ended by November 2002.

Members of the Supervisory Board forthis report period are:

The Scientific-Technical Committee iscomprised of heads of departments and anequal number of elected members from theInstitute, and advises the Supervisory Boardand the Managing Directors on all importantscientific and technical matters.Further, the HHI has appointed a ScientificAdvisory Committee of experts from indu-stry, the Deutsche Telekom AG and the aca-demic sector. Members and permanentguests of the Scientific Advisory Committeefor this report period are:

Prof. Dr. G. Litfin, (chair), LINOS AG, GöttingenMinDirig Dr. K. Rupf, (1st vice-chair), Bundesministerium für Bildung und Forschung, BonnORR B. D. Lietzau, (2nd vice-chair), Senatsverwaltung für Wissenschaft, Forschung und Kultur,BerlinProf. Dr. J. Eberspächer, Technische Universität MünchenM. Ferstl, HHI, BerlinProf. Dr. P. Noll, Technische Universität BerlinMinR W.-P. Ottenbreit, Deutsche Telekom AG, BonnRD K. Trantow, Senatsverwaltung für Finanzen, BerlinDr. H. Venghaus, HHI, BerlinMinDirig M. Cronenberg (guest), Bundesministerium für Wirtschaft und Technologie, Berlin

Prof. Dr. J. Eberspächer, (chair), Technische Universität MünchenDr. R. Fechner, Lucent Technologies Network Systems GmbH, NürnbergProf. Dr. G. Fettweis, Technische Universität DresdenDr. H.-J. Grallert, Marconi Communications ONDATA, BacknangProf. Dr. W. Klimek, Deutsches Zentrum für Luft- und Raumfahrt e.V., KölnProf. Dr. P. Leuthold, Eidgenössische Technische Hochschule ZürichDr. M. Rocks, T-Nova Deutsche Telekom, BerlinDr. G. Ruopp, Marconi Communications GmbH, BacknangDr. B. Schwaderer, Tesat-Spacecom GmbH & Co. KG, BacknangProf. Dr. G. Siegle, Robert-Bosch-GmbH, BonnDr. E. Zielinski, Alcatel SEL AG, StuttgartMinR K. Kreuzer (guest), Bundesministerium für Bildung und Forschung, Bonn

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Executive Director

Prof. Dr. Joachim Hesse +49-30-31 002-200 hesse@hhi.de

Departments

Optical Networks Dipl.-Ing. +49-30-31 002-455 walf@hhi.deGodehard Walf

Optical Signal Processing Dr. Hans-Peter Nolting +49-30-31 002-427 nolting@hhi.de

Broadband Mobile Prof. Dr. Dr. +49-30-31 002-540 boche@hhi.deCommunication Networks Holger Boche

Materials Technology Dr. Norbert Grote +49-30-31 002-431 grote@hhi.de

Micro Fabrication Dr. Udo Niggebrügge +49-30-31 002-550 niggebrueggeTechnology @hhi.de

Integration Technology Dr. Herbert Venghaus +49-30-31 002-555 venghaus@hhi.de

Image Processing Dr. Ralf Schäfer +49-30-31 002-560 schaefer@hhi.de

Interactive Media – Dr. Siegmund Pastoor +49-30-31 002-210 pastoor@hhi.deHuman Factors

Central Services

Administration Dipl.-Ing. +49-30-31 002-310 mrowka@hhi.deHartmut Mrowka

Press and Public Relations Dr. Wolf von Reden +49-30-31 002-330 reden@hhi.de

Marketing/ Dr. Walter Döldissen +49-30-31 002-253 doeldissen@hhi.deBusiness DevelopmentPhotonics Coordination

Quality Management Dr. Herbert Engel +49-30-31 002-389 engel@hhi.de

Organisation and Contact Persons

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R & D Activities

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R & D FIELDS

Photonic Networks

Topics and Results

The worldwide communication traffic con-tinues to increase at a growth rate of about100 % per year. The main driving force be-hind this development is the Internet, whichwill evolve over the next few years into aBroadband Internet with an even higher de-mand for bandwidth. The Internet will bethe backbone of the future information soci-ety and the mainspring for commerce andbusiness. The basis of this high capacity com-munication system will be optical fibre com-munication, which will utilize photonic net-works in the core network and broadband fi-bre in-house networks at the customers’premises. Prognoses for access data rates are150 Mbit/s for private customers and severalgigabit per second for business customers.The enormous fibre capacity of more than60 terahertz will be accessible using opticalwavelength-division multiplexing (WDM) andoptical time-division multiplexing (OTDM)techniques. In photonic networks the infor-mation is not only transmitted optically, butalso routed in the optical domain.

The R&D activities of HHI comprise all as-pects of photonic networks, from photoniccomponent technology to the systems side;e.g. exploitation of the large fibre band-width, optical switching, network investiga-tions, optical signal processing, and compo-nent developments. The projects are fundedby the German government, the State ofBerlin, the European Union, the informationand communication industry and networkoperators.

During the last four years, one of the high-er-ranking goals of the German research ini-tiative KomNet, which finished in 2002, wasto develop a set of system-level solutions forthe future broadband Internet through 25individual R&D projects, mainly lead by in-dustrial partners, and to perform cross-pro-ject testing and demonstrations under real-life operating conditions. In particular the in-terworking of high-technology photonic sys-tems developed by various manufacturerswas tested and field-trialled using the exist-ing standard single mode fibres, which arewidely used throughout Europe.

HHI contributed to the KomNet programwith several projects, as well as through sub-contracts to industrial partners. These pro-

jects and subcontracts included the designand simulation of optical networks, a looptestbed for WDM network elements, ultra-high speed transmission using time-divisionmultiplexing, 40 Gbit/s photodetectors andreceivers, all-polymer add-drop multiplexers,optical signal regenerators, transceiver pho-tonic integrated circuits, and picosecond op-to-electronic integrated circuits. In addition,the HHI Systems Integration Office was re-sponsible for coordinating the experimentalnetwork construction and cross-project fieldtrials. The large number of excellent resultsachieved provide a solid basis for solving cur-rent tasks of product-oriented development,and for further research on photonic com-munication networks, e.g. under the frame-work of the German Government’s newfunding priority called MultiTeraNet. Thisprogram addresses topics such as flexible op-tical networks, access networks, exploitationof the fibre capacity and key componentsand technologies.

The main objective of photonic research atHHI is to make substantial contributions tothe development of photonic networks. Thefollowing main areas are being addressed:• Photonic networks and systems• Ultra-fast optical signal processing and

transmission• InP components and OEICs• Photonic components based on polymers

and SiO2/Si

HHI is a partner in the project “OpticalTechnologies in Motion for the IST Program”(OPTIMIST). This project aims to facilitateconcerted action in the general area of pho-tonics across the whole of the EuropeanR & D program IST (Information Society Tech-nologies). In particular it will encourage im-portant synergies and interchanges, for ex-ample between systems projects and compo-nent projects, and improve the mutualawareness between industry and academiaof new ideas and the results of longer-termresearch in the area of photonic technolo-gies. These objectives will be achieved by or-ganising topical workshops and meetingsand a range of other dissemination activities.

The overall research area of photonic net-works is focussed on the two areas Core andMetro Network and Access and CustomerNetwork.

Core and Metro Network

Work in this research area concentrates ondense wavelength-division multiplexing(DWDM) and high bitrate time-division mul-tiplexing (TDM) techniques, optical crosscon-nects, and optically transparent networks.Multiplexing and demultiplexing may beperformed either electrically (ETDM) or opti-cally (OTDM) in high bitrate TDM. The gen-eration, modulation, detection and synchro-nization of the optical signals are importantissues being studied. The effects of the pho-tonic components and of fibre nonlinearitiesand dispersion on the quality of the opticalsignals are also under investigation.

Optical time division multiplexing(OTDM): The optical time division multiplex-ing (OTDM) work includes the investigationand realization of optical subsystems, and al-so transmission experiments at bitrates ashigh as 160 Gbit/s. An OTDM transmissionsystem comprises several components andsubsystems. On the transmitter side an opti-cal pulse source generates a pulse train witha repetition frequency at the base rate, whichin our case is 40 GHz, the highest electronicdata rate available at present. This opticalpulse train is coupled into four opticalbranches in which the 40 Gbit/s electrical sig-nals are modulated onto the optical pulsestreams. These four optical signals are bit-in-terleaved by a delay multiplexer to generatea 160 Gbit/s bit stream, which is transmittedvia monomode fibres from various suppliers.At the receiver side, an optical demultiplexerseparates the four base signals for subse-quent electronic detection and processing.The demultiplexer must be very fast for bit-wise switching. The RZ data source is real-ized by a mode-locked laser. This data sourcehas been demonstrated in 160 Gbit/s trans-mission experiments over unrepeatered (nooptical amplifiers in the transmission line)transmission spans of up to 160 km of stan-dard fibre. To compensate for fibre disper-sion, we applied passive dispersion compen-sation using dispersion-compensating fibre.

We reported the first 160 Gbit/s OTDMsystem, which used optical demultiplexing tothe base data rate of 40 Gbit/s, electrical sig-nal processing at 40 Gbit/s, and transmissionover standard single-mode fibre (SMF). Thisis the first demonstration of next generationOTDM systems, which will use optical de-multiplexing to the highest electrical pro-cessing speed available.

In-service quality monitoring of high bit-

rate optical transmission systems working at160 Gbit/s has been achieved at the full linerate by using optical sampling systems.These systems provide the picosecond tim-ing resolution needed to observe eye dia-grams at this speed. Key devices are theclock recovery device and the fast switch forsampling. The clock recovery circuit containsan optical phase locked loop (PLL) in whichthe ultra-fast optical mixer is realized by asemiconductor laser amplifier in a loop mir-ror (SLALOM). The sampling gate is a non-linear optical loop mirror (NOLM) containing320 m of highly nonlinear fibre (λ0 =1547 nm).

All-optical signal regeneration: Scalablenetworks need full 3R (re-amplification, re-shaping, re-timing) signal regeneration. Com-ponents and methods for this function areunder development. Optical clock recovery isperformed using self-pulsating DFB feedbacklasers. These three-section devices are con-trolled by three dc currents, which switchthe self-pulsation on and off and tune its fre-quency. Very large (two octave) tuningranges at frequencies of more than 80 GHzhave now been achieved using the newPhaseCOMB architecture based on a tandemDFB laser structure. The self-pulsation fre-quency synchronizes to the optically injecteddata signals, and thus realizes all-opticalclock recovery.

A novel type of self-pulsating laser basedon the “Amplified Mirror Concept” has beendeveloped. First devices have been fabricatedand characterized. This component has onlyone DFB section and one amplifier section.This simplifies the fabrication, which resultsin higher yield.

The influence of internal reflections hasbeen investigated to improve the yield ofchirp-free, low jitter and high extinction ratioself-pulsating lasers. Automatic characteriza-tion of multi-section lasers has also been in-troduced.

A new switching architecture based on analternating data clock scheme (ADC) hasbeen successfully used for 3R regeneration at10 and 40 Gbit/s. This architecture has anumber of advantages over commonly usedcircuits. With the use of ADC, any wave-length converter can be used as a decisionelement in a 3R regenerator. The speed limitof optical semiconductor amplifiers (SOAs) isincreased significantly by this scheme.Specially important for DWDM systems is thefree choice of the output wavelength of aCW laser. Applying this concept, the first

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semiconductor-based all-optical 3R regenera-tor at 40 Gbit/s has been realized.

In cooperation with ALCATEL, an all optical3R regenerator for 160 Gbit/s is under devel-opment. The key components are thePhaseCOMB laser for clock recovery and theMach-Zehnder (MZ) SOA switch as the syn-chronous modulator.

A first step was taken towards a 160 Gbit/s3R regenerator based on a hybrid electro-op-tic architecture. A 3R regenerative wavelengthconverter at 160 Gbit/s was demonstrated. Itcomprised four elements: a pulse shaper, adecision gate, an optical clock and a wave-length shifter. The decision gate was realizedusing cross-phase modulation in highly non-linear fibre with the nonlinear coefficient γ =20 W-1 km-1. An optical gate based on thesame fibre was also operated in an opticalsampling system for monitoring eye dia-grams at data rates up to 320 Gbit/s. Finally,a new optical clock recovery unit for datarates up to 160 Gbit/s was developed basedon electro-absorption modulators.

Monolithically integrated picosecondpulse source: One area of prime interest toHHI is the development of components andsubsystems for OTDM/WDM systems withsingle fibre transmission capacity in the ter-abit per second range. Key components for160 Gbit/s OTDM systems are pulse sourceswith 40 GHz repetition rates and less than1.5 ps pulse widths, and a monolithically in-tegrated mode-locked laser meeting thesedemands is currently under development. Inparticular, a 2.2 ps pulse width and a500 MHz tuning range with less than 300 fsjitter have been demonstrated.

Monolithically integrated nonlinear in-terferometer switches: We have fabricatedand investigated nonlinear Mach-Zehnder in-terferometers for use as demultiplexers. Theseuse optical semiconductor amplifiers (SOAs)as nonlinear elements in the interferometerarms. With these all-optical switches, error-free demultiplexing from 160 to 10 Gbit/swith arbitrary choice of the switched channelwas achieved in system experiments. The re-duction of the polarization sensitivity of theseswitches is a crucial task for application in anetwork. Less than 2 dB polarization sensitiv-ity for the signal path have been demonstrat-ed. Furthermore a reduction of the opticalloss is necessary.

In a new project with ALCATEL, the speedof the MZ-SOA switch will be increased to useit as a synchronous modulator up to 160 GHz.

High-speed modulators: 40 Gbit/s optical

modulators are key components for next-generation optical communication systems.LiNbO3 modulators for this task are commer-cially available, but require relatively large RFdriving voltages (more than 6 V), and as aconsequence need very expensive drivingelectronics.

GaAs devices are more favourable in thisrespect, but even better performance andlower driving voltages are expected fromInP-based modulators. The Mach-Zehndermodulator structure we developed is basedon a travelling wave electrode design to en-sure proper high speed characteristics. It ismuch smaller (less than 3 mm2) and needsless driving voltage (VPP ≈ 2V) than compara-ble devices made with GaAs or lithium nio-bate. This inherently low driving voltage isone of the key issues for future transmissionrates of 80 Gbit/s and more.

High-speed photodetectors and receiv-ers: The R & D project TWINPD, a part of theKomNet initiative, was completed in 2002. Itresulted in the fabrication of several differen-tial photodetector modules. The achieve-ments included bandwidths exceeding45 GHz, differential polarization-dependentlosses as low as 0.15 dB, an output currentasymmetry of only 0.2 dB, and better dy-namic behaviour than with single photodi-odes. These receiver modules were success-fully applied in a field trial conducted by anindustrial partner. Balanced photodetectorswere also developed using the same integra-tion scheme. When packaged into modules,they had well opened eye patterns at40 Gbit/s.

The pinTWA photoreceiver, comprising awaveguide-integrated photodiode and aHEMT-based travelling wave amplifier, wasimproved by implementing a galvanic sepa-ration between the amplifier’s ground andthe RF output ground. This avoids the lossyand costly bias-T, which has hitherto beenneeded to operate the pinTWA photore-ceivers. A bitrate conversion capability of60 Gbit/s was demonstrated.

The development of even faster photore-ceivers is continuing in the MultiTeraNetProgram. Here the goals for broadband op-toelectronic conversion rates are extendedinto the 80 to 160 Gbit/s data range. In par-ticular, receivers operating at 80 Gbit/s are ofimmediate interest for our industrial part-ners, as they intend to carry out first systemtrials at this extended transmission speed inthe near future. HHI’s role withinMultiTeraNet is to develop broadband pho-

toreceivers for this data range and to providesamples to its industrial partners within thenext three years.

The activities with high-speed photodetec-tors and receivers are complemented by aproject in which, in cooperation with theFraunhofer Institute for Reliability and Micro-integration, advanced packing technologiesfor frequencies of up to 100 GHz are beingdeveloped.

Design strategies to utilize the maxi-mum transmission capacity of WDM sys-tems: The goal of this novel topic is to devel-op upgrading strategies to exploit the maxi-mum capacity of modern fibre systems. Thestrategy starts with the C band and contin-ues to the whole optical bandwidth of singlemode fibres, covering the wavelength regionfrom 1300 nm to 1675 nm. This region pro-vides a nominal information bandwidth ofabout 50 THz. The upgrading strategy shouldallow the addition of new optical bandswithout disturbing the already existing ones.This is of great practical interest for networkproviders operating different systems on dif-ferent fibre infrastructures. As an example,the application of Raman amplification mustbe considered when upgrading the links.Mutual influence through nonlinear interac-tions is expected by implementing a pluralityof Raman pump channels within combs ofclient information channels.

Another problem not yet well understoodis polarization-mode dispersion at very highchannel rates in conjunction with nonlineareffects. It is planned to investigate the trans-mission properties of WDM systems with anextremely large number of channels by sim-plified simulations and analytical methods.The theoretical results are to be verified in se-lected experiments at WDM channel rates upto 40 Gbit/s, taking into account various fi-bre types, various dispersion managementschemes, various amplification methods aswell as novel modulation formats. The overallgoal of this collaborative research project isto provide robust design solutions with real-istic tolerances for national and pan-European ultra-high capacity networks.

WDM system testbed for novel networkapplications: HHI operates a powerful mea-surement system for the investigation of vari-ous aspects of future DWDM networks. WDMsystems with up to 16 wavelength channels,each up to 10 Gbit/s, can be tested. This isbeing extended to 40 Gbit/s channel rates.

Long distances are simulated using multi-ple round trips in a WDM loop testbed.

Multiple round trips correspond well withthe ITU-T proposals to build networks withidentical sections. The optical transmissionsections include transmission fibres, opticalamplifiers, and means for chromatic disper-sion compensation. The transmission fibrefor the 10 Gbit/s channels is 80 km of stan-dard SMF, and is compensated for dispersionusing dispersion-compensating fibres.

All tests and measurements performed inthe WDM testbed are accompanied by nu-merical simulations. The agreement betweenmeasurements and simulations gives confi-dence in the correctness of both the mea-surement procedure and the numerical mod-els.

Distributed Raman amplification: Distri-buted Raman amplification uses the trans-mission fibre as a gain medium and promisesoptical links with virtually zero attenuationover large wavelength ranges. The dynamicsof Raman-amplified links have been investi-gated in the cases of switched data signals(burst-mode traffic) and switched channelsto verify the properties of these links in re-configurable networks and with discontinu-ous data streams. These links have beencompared to those using EDFAs. The ob-served signal power peaks, caused by ampli-fier saturation effects, show that distributedRaman amplification generates significantlylower power peaks than EDFAs if signals areswitched, even in the case of numerous(e.g. 50) cascaded amplifiers. To evaluatelong-haul all-Raman amplified WDM sys-tems, a switched transmission simulation hasbeen performed in our ring network. Theswitching-induced signal power peaks of the65 cascaded distributed Raman amplifiers inthe 2600 km link are only 2.4 times largerthan the steady state signal power. Thus, us-ing Raman amplification only a moderateamount of gain control is needed to com-pensate for signal power variations.

Channel identification and performancemonitoring: A problem not solved so far ischannel identification and performance con-trol in a transparent WDM network. This ismost important in switched WDM networks.Novel control modulation techniques are be-ing tested that allow simultaneous identifica-tion and performance control. Two conceptscombining a 50 Mb/s control channel and a10 Gbit/s payload channel were found togive good correlations between the twochannels, as required for performance con-trol, and to give error-free transmission inboth channels up to distances of 2500 km.

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Network and subsystem simulation andmodelling: Methods for simulating opticalcomponents and signal propagation in anoptical path are being developed, and arebeing checked by comparison with the ex-perimental measurements. The limitationsdue to noise and crosstalk of the size andcascadability of switching nodes for opticalburst switching (OBS) are being simulatedand analysed. As well as the programs wehave developed ourselves, we also use thecommercially available program package“VPITransmissionMaker & VPIComponentMak-er” from Virtual Photonics Inc. (a spin-offfrom HHI) to perform these simulations.

With the transmission-line laser model it ispossible to optimize photonic componentsand subsystems, such as the self pulsatinglaser and the nonlinear Mach-Zehnder inter-ferometer (used as a very fast optical gate),which can be connected to an all-optical cir-cuit for 3R regeneration. The work towardshigh bitrate TDM, as well as the combinationof TDM and WDM technologies, is also sup-ported by analytical and numerical investiga-tions, the main question being how to set upthe transmission line to achieve optimumtransmission capacity.

The performance of highly dynamic opticalswitched networks and the interaction of dif-ferent protocol layers are being investigatedusing “OPNET Modeler”, a simulation tool todesign and study communication networks,devices, protocols, and applications. Opticalburst switching is a promising candidate fora more dynamic optical layer in the nextgeneration Internet. Therefore the IP through-put of OBS networks will be simulated andcompared with that of traditional IP net-works.

Transinet – Innovative transport net-works for the broadband Internet: The ob-jective of this joint project, which was begunin 2000 together with T-Systems Nova andpartners from universities, is to develop newnetworking technologies to carry IP trafficover WDM optical networks in an efficientmanner. The main research areas for thenext-generation optical Internet in theTransiNet project are new concepts for net-work and node architectures, the corre-sponding protocols, standards and technolo-gies, traffic aggregation, scalability of WDMnetworks, quality of service, network man-agement, resilience, and the interworkingand integration of high-speed photonic andmobile communication systems. At HHI ad-vanced optical subsystems such as WDM

transmission, add-drop multiplexers, opticalcrossconnects and wavelength router/switch-es, together with their interworking withhigher-layer protocols, mainly IP, are beinginvestigated. Furthermore, parts of an IP-op-timized air interface will be developed. Themain research areas for wireless communica-tions are new signal processing algorithms,estimation of the radio channel, resource al-location, and teletraffic techniques for theplanning process.

Design and analysis of WDM networksfor IP: Optical networking is based on twocomplementary views, which are reflected inrecent ITU-T recommendations and the cur-rent activities of the study groups. The func-tional view is mostly related to the manage-ment aspects, and the physical view to thetransmission issues of the different networktopologies. The problem of designing trans-parent network domains is due to the ana-logue character of the channels. This compli-cates network planning because of the limit-ed cascadability of the network elements andthe difficulties of controlling the channels, es-pecially in switched networks.

Upgrading of basic network topologies to-wards switchable WDM networks is planned.This requires the application of wavelength-switchable transmitters, the implementationof optical crossconnects and the develop-ment of burst-mode receivers with fast clockrecovery. Novel labelling techniques androuting measures are being simulated andtested in the WDM testbed.

Access and Customer Network

Broadband access and in-house networksare prerequisites for both business and pri-vate customers for future multimedia Inter-net communication. Current solutions forproviding capacities of more than 100 Mb/sto residential customers and up to several gi-gabits per second to business customers andenterprises are too expensive in both installa-tion and operation, and are not ready forvolume production.

BaiNet – Optical broadband access andin-house network architectures: This newproject aims to create solutions for cost-effi-cient optical access and in-house networks,including wireless extensions to mobilebroadband terminals for indoor applications.In close cooperation with two industrial part-ners, network concepts and solutions will be

developed and investigated by simulationsand experiments, especially the technicaland economical issues, with emphasis on op-erator and customer requirements.

Monolithically integrated laser compo-nents for optical transceivers: The bidirec-tional optical transceiver is a key componentfor the realization of optical subscriber links.Since they are required for cheap and reli-able subassembly, recent work has focussedon the development of Fabry-Perot laserOEICs with integrated laser resonators, fieldtransformers to reduce the numerical aper-tures, and integrated 45° mirrors. Severalwafers have been processed successfully andabout 100 chips have been forwarded to theindustrial partner for assembly and reliabilitytests.

Another concept for hybrid structures re-lies on lasers and semiconductor optical am-plifiers combined with waveguide structuresin silicon-on-insulator (SOI). Large refractiveindex steps in the SOI will enable very com-pact structures. The challenge for the devel-opment of the InP-based lasers is the mono-lithic integration of proper spot size trans-formers and the realization of geometricalstructures supporting passive hybrid mount-ing (with low losses and high positioning tol-erances).

10 Gbit/s lasers and detectors: With thefurther deployment of metropolitan and ac-cess networks in the coming years, a main-stream product for fibre optics networks willbe 10 Gbit/s transceivers. A crucial compo-nent in such a device is the laser. The perfor-mance requirements are extremely demand-ing in terms of current and power consump-tion, behaviour at high temperatures, largesignal modulation characteristics, fibre cou-pling efficiency and alignment conditions,cost issues, and aging characteristics. To thisend, optimization of InGaAsP/InP BH lasershas continued. 1.55 µm FP devices incorpo-rating a spot-size converter in the form of atapered active stripe largely meet these de-mands. 1.3 µm lasers were also developed.The active tapered stripe design could alsobe successfully adapted to DFB lasers, thanksto the development of a special e-beam writ-ing strategy to generate continuously chirpedgratings. In addition to InGaAsP-based lasers,1.3 µm RW structures with an InGaAlAs ac-tive medium have been developed to furtherimprove the high temperature characteris-tics. Superior threshold current densities ofbelow 50 A/cm-2 per QW layer wereachieved with this material. The activities

with discrete transmitter lasers are comple-mented by a PhD thesis on vertical cavitylasers that focusses on the use of oxidizedmirrors.

Equally important for such transceivermodules are low-cost photodetector devices,which have to fulfil stringent demands withrespect to responsivity, bandwidth, dark cur-rent, long-term stability, and ease of chipmounting and fibre-chip coupling. Thereforethe development of bottom-illuminatedInGaAs/InP pin photodiodes for the 1.3 µmwavelength has been started. These includean integrated biasing network and are suit-able for flip-chip bonding on a silicon bench.For photodiodes with a rather large activearea diameter of 32 µm, which is necessaryto provide sufficiently wide alignment toler-ances during flip-chip assembly, a 3 dB band-width of 13 GHz and a high responsivity of0.9 A/W were obtained. Further develop-ments aim at the monolithic integration ofthe photodetector with a transimpedanceamplifier and the extension of the receiverdata rate towards 40 Gbit/s. In addition, top-illuminated photodiodes for a wavelength of1.06 µm were fabricated for applications inoptical satellite communication systems op-erating at 10 Gbit/s.

Microring structures: Microrings are build-ing blocks for various optoelectronic devicessuch as filters, tunable dispersion compen-sators, ring lasers and wavelength convert-ers. Ring radii are typically in the 100 µmrange and ring structures are frequentlycombined with monolithically integratedgain sections (SOAs), primarily to ensure suf-ficiently low total device losses. High photondensities in such ring structures are particu-larly favourable for wavelength conversionbased on four wave mixing, and correspond-ing experiments have been successfully com-pleted.

WDM filter components: Polymer-basedcomponents are generally attractive becauseof their low-cost potential. Last year we in-troduced an all-polymer AWG device thatfeatures an extremely low temperature de-pendence of the operating wavelengths(“athermal” AWG). This work has been con-tinued to explore a suitable technologicalmethod for wavelength trimming. Exposingthe polymer chip to gamma rays proved tobe a viable technique.

Another activity that relies on polymer ma-terials is the development of an optical add-drop multiplexer (OADM) in which AWGsand switches will be used as building blocks.

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An innovative, very compact OADM archi-tecture featuring low optical crosstalk hasbeen designed. A novel triazinacrylate-basedpolymer material was used. This was devel-oped by the collaborating partner FhG-IZMand is characterized by an optical loss level of0.4 dB/cm.

The combination of polymer and silicawaveguides offers the advantage of using thesilica for the low-loss transport of light andthe polymer for efficiently performing switch-ing functions. This technology, introduced acouple of years ago, is now being used toimplement chromatic dispersion compen-sators for 10 – 40 Gbit/s systems. Microringresonator structures for this purpose weresuccessfully fabricated and characterized.

Work on an optical beamformer PLC chipwas continued, using the conventional silica-on-silicon materials platform. This chip isused to optically control the beam character-istic of a smart 60 GHz microwave antenna.In the reporting year the optical phase con-trol and the optical amplitude control sec-tions, which were previously implemented astwo separate chips, were successfully inte-grated onto one 8-channel chip in order toachieve a much more compact structure.

Enabling Technologies for FuturePhotonic Network Components

Ultra-fast optoelectronic materials: Long-term roadmaps for optical fibre transmissionsystems predict transmission rates in the ter-abit per second range (for one wavelengthchannel) in the next decade. To accomplishthis goal, much basic research still needs tobe done to realize the required ultra-fastcomponents. This includes particularly a searchfor suitable materials. Attractive candidatesto exploit inherently fast intrasubband transi-tions are the InGaAs/GaAlAsSb QW materialson InP. Established devices (at wavelengthsmuch greater than 2 µm) relying on such ef-fects are quantum cascade lasers. The goal ofour work is to shift the operating wavelengthinto the 1.55 µm range using the Sb-con-taining QW mentioned above. Other con-ceivable devices, apart from lasers, are ultra-fast optical amplifiers and all-optical switch-es. So far MBE-based InGaAs/GaAsSb MQWlayers of high quality have been developed.

Photonic crystals: Photonic crystals areexciting new materials in photonics, andapart from the corresponding fibre structures(“holey fibres”), photonic crystals are still at

the stage of fundamental research. HHI is ac-tive in this area using both the InP and thesilicon-on insulator (SOI) material systems.Most challenging to achieve is the periodicstructuring, with lateral dimensions in the100 nm range and etch depths about oneorder of a magnitude larger, and with a suffi-ciently high degree of regularity to ensuremoderate overall propagation losses. Corres-ponding two-dimensional structures havebeen fabricated in GaInAsP/InP as a prelimi-nary step towards planar devices such aswaveguides, bends and splitters. Waveguidestructures in SOI have also been realized.

Competencies

Investigation and development of architec-tures for photonic networks, development ofplanning guidelines, and studies of specificproblems of photonic networks

Characterization and testing of optical net-works and network components, including ex-periments on fibre loops, transmission exper-iments over large distances, and field trials

Development of high rate optical WDM sys-tems (10 and 40 Gbit/s per channel) and thecorresponding measurement methods

Investigation, design and development ofoptical WDM LANs and MANs, optical accessnetworks and passive optical networks

Development of methods for the control andsupervision of networks

Development, application and verification ofsimulation software for optical transport net-works

Design and development of optical systemsusing heterodyning

Development of wavelength conversionmethods for WDM systems

Investigation and development of high rateOTDM subsystems (40 to 160 Gbit/s andabove), including multiplex/demultiplex, hy-brid 3R signal regeneration and add/droptechniques

Development of methods for purely opticalclock recovery at bitrates of 10 to 160 Gbit/s

Development of ultra-fast switching devicesbased on SOAs for bitrates of 10 to 160 Gbit/s

Development of circuit architectures and ofphotonic components for all-optical 3R sig-nal regeneration

Development of methods for the control,maintenance and supervision of high rateOTDM subsystems

Development of methods for the generationof ultra-short optical pulses

Development of optical sampling methodsfor network monitoring up to 320 Gbit/s

Optimization of methods of dispersion man-agement

Design and development of optical frequen-cy reference equipment

Design and fabrication of transponders andoptical synchronous digital hierarchy (SDH)front ends

Development, fabrication and characteriza-tion of fibre optic components

Development, fabrication and characteriza-tion of methods and devices for chromaticand polarization mode dispersion (PMD)compensation

Development, fabrication and characteriza-tion of opto-electrical components and pho-tonic integrated circuits based on InP and“passive” materials:- Optical amplifiers with spot-size

transformers- High-speed laser diodes- Wavelength converters- Demultiplexers and add/drop multiplexers

for OTDM applications- Components for optical clock recovery and

signal regeneration (self-pulsating lasers)- Integrated transceivers- Top and bottom illuminated 10 Gbit/s

photodetectors- Fast waveguide-fed, high-power photodi-

odes with optical spot-size converters- Differential mode photodetectors (twin

photodiodes) with integrated spot-size converters

- High bitrate optical receiver front ends with integrated spot-size converters

- High-speed monolithically integrated pulse sources

- Optic/microwave converters

Polymer-based thermo-optic switches, switchmatrices, and filters

Optical components based on mixed poly-mer/silica technology

Planar waveguide components on SiO2/Siand SOI

Diffractive optical components

Photonic crystals

Modelling of photonic components, photon-ic subsystems and integrated circuits

Development, optimization and applicationof component technologies:- Clean room laboratories (class 10/1000)- Epitaxy (MOVPE, MBE) of InP-based

semiconductor materials- Secondary ion mass spectroscopy (SIMS)- CAD/CAM of photolithography masks- Electron beam lithography and optical

lithography- High resolution scanning electron

microscopy- Atomic force microscopy- Dry etch processes (reactive ion etching,

ion beam etching) with endpoint detection- Rapid thermal processing- Deposition of metal and dielectric layers

(evaporation, sputtering, plasma deposition)

- Optical coatings- Characterization and technology of optical

polymer materials- Chip mounting and connection techniques- Fibre-chip coupling (single and multiple

input/output ports)- High-frequency packaging

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Mobile Broadband Systems

Topics and Results

The HHI activities in mobile communica-tion concentrate on improvements for sys-tems of the third generation, such asUMTS/IMT2000, and on the design of WLANand fourth generation systems.

Due to the extreme costs of spectral band-width, improvement of the spectral efficien-cy of UMTS is essential to increase the overallsystem capacity and to give an acceptablereturn on investment within reasonable timespans. Therefore smart antenna systems,multiuser detection principles and advancedscheduling algorithms to improve the spec-tral efficiency of UMTS are being investigat-ed. Strategies are also being developed thatallow for the strongly asymmetric traffic offuture services, such as IP over wireless, andto achieve the potential gains of cooperativesystems.

New approaches are being investigated forefficient resource allocation in future mobilesystems, including consideration of the char-acteristics of new services. In particular, fun-damental principles for an IP-optimized mo-bile communication system are being investi-gated. Also, new multiuser receivers arebeing conceived and signal processing algo-rithms are being optimized. In addition,work is proceeding on the integration of mo-bile and photonic networks. New conceptsfor fourth generation systems are being de-veloped for multiple access control, interfer-ence reduction and network planning. Thesemethods are based on the application of op-timization techniques to code division multi-ple access (CDMA) systems, orthogonal fre-quency division multiplex (OFDM) systems,and non-orthogonal multiple carrier systems.

Future cellular systems must be able tosupport high-rate multimedia services evenwith high user densities. This challenginggoal can be attained by using antenna arraysat the base station. One way to make effi-cient use of the spatial diversity provided bythe array is to steer the receive and transmitbeams towards the desired users, with theradiation pattern periodically updated de-pending on the instantaneous channel char-acteristics. In this way considerable carrier-to-interference gains can be achieved, whichmay be directly traded for improved qualityof service, greater user density, or greater da-ta rate.

The HHI carries out theoretical and experi-

mental research in the field of beamformingand applies this knowledge to the design ofnew algorithms for both up-link and down-link space-time processing. Starting from thebasics of information theory, new resultsconcerning the duality between downlinkmultiplexing and uplink multiple access haverecently been obtained. The transmit strate-gy for the downlink has been thoroughly dis-cussed and a highly competitive array pro-cessing algorithm balancing the signal-to-noise ratios at different terminals at a min-imum cost of transmitter power has beenpatented. The algorithm is also efficient forheterogeneous user distributions.

Compared with the conventional matchedfilter receiver, a multiuser receiver that uti-lizes the structure of the multi-access interfer-ence can substantially increase the spectralefficiency of CDMA using direct-sequencespread-spectrum methods. An important ob-servation is that both the performance andcomplexity of such receivers strongly dependon the choice of the spreading sequences.Moreover, if signals are transmitted via atime-variant multipath channel, careful de-sign of the training sequences is required toensure small channel estimation errors.Hence we have been active in the design andallocation of spreading and training se-quences to achieve the best performance ofCDMA-based mobile communication sys-tems.

There is a new class of smart multi-elementantenna (MEA) systems that are promisingcandidates for wireless mobile systems withvery high spectral efficiencies and capacities.These are based on MEAs at both ends of thewireless link, with space-time encoding atthe transmitter, simultaneous transmission ofdifferent data streams with the same carrierfrequency, and signal reconstruction at thereceiver. Repeated estimation of the complexmatrix channel elements is required for sig-nal detection in the quasi-stationary flatRayleigh fading environment. Several sets ofalgorithms and hardware architectures formultiple-input multiple-output (MIMO) chan-nel estimation and for signal recovery in vari-ous MEA systems have been investigated andcompared with Lucent’s VBLAST demonstra-tor. All systems have been designed to sup-port high-speed real-time indoor WLAN ap-plications.

In order to improve the performance,methods that can make use of channel stateinformation (CSI) at the transmitter havebeen particularly investigated. The capacity

of a multi-antenna system may be increasedeven with partial CSI at the transmitter.Optimal transmission methods with covari-ance feedback have been investigated andthe tradeoff between spatial multiplexingand diversity with covariance feedback hasbeen analyzed. Note that WLANs operate inthe time-division duplex mode, where fullCSI for the down-link may be obtained fromthe up-link due to reciprocity. The patentedconcept was therefore based on linear chan-nel inversion, which needs a simple matrix-vector multiplication at the transmitter in or-der to de-correlate the signals at the receiveantennas. In cooperation with MEDAV GmbH,a large number of broadband MIMO chan-nel measurements with up to 16 antennas atboth the transmitter and receiver have beenrecorded at 5.2 GHz in order to evaluate thepotential of MIMO for WLAN applications inindoor and close-to-indoor urban outdoorenvironments.

The result was that, with proper antennadesign, very high spectral efficiencies, closeto those obtained with independent Rayleighfading (above 80 bps/Hz at 20 dB signal-to-noise ratio with 16 transmit and 16 receiveantennas), are indeed achievable, since theRician factor is rather small in those environ-ments; i.e. the scattering is significant. It be-came clear that the antenna design has a sig-nificant impact on the achievable capacity,particularly in outdoor environments. Themain factors influencing performance havebeen investigated experimentally.

Although much can be done at the anten-nas to increase the capacity, sometimes thecapacity may actually be reduced, especiallyif there is little scattering. This corresponds toa low effective rank of the MIMO channelmatrix. Signal processing must be moreadaptive to transmit the data more reliably inthis case. A new patented system conceptbased on linear matrix-vector operations atboth the transmitter and receiver was there-fore developed, called adaptive channel in-version. The main idea is to maximize thethroughput by matching the number of par-allel data streams to the effective dimensionof the signal space. In this way, reliable oper-ation in all kinds of MIMO channels becomespossible, and the signal processing load re-mains reasonable. Experimental work is nowconcentrated on the implementation of ademonstration system based on a hybridFPGA/DSP approach.

In addition, a patented technique for jointspace-time equalization of MIMO channels

with minimal effort has been developed andan iterative algorithm for joint detection andchannel estimation in MIMO systems usingspace-time codes has been proposed. Thepotential of MIMO in multiuser scenarios isalso being investigated. There are still severalopen research problems, one of which is theissue of fair scheduling between the users.An algorithm to optimize the sum rate in theuplink has recently been found.

Recent research is also concerned with co-operative concepts in wireless communica-tions. At the borders of a WLAN cell, for in-stance, transceivers might get access to thenetwork by using transceivers inside the cell.Thus the coverage area may be increased,but the effects on capacity and energy con-sumption are still an open issue. The poten-tial of cooperative techniques is presently un-der evaluation using a system model similarto MIMO.

The combination of OFDM and smart an-tennas (MIMO-OFDM) turns out to be apromising candidate for future fourth gener-ation mobile systems, since it promises highspectral efficiency and low-complexity equal-ization in the most demanding wireless envi-ronments. The capacity of this system con-cept was investigated, starting with a physi-cal description of the underlying broadbandspace-time channel, with very encouragingresults. Channel estimation is crucial for ex-ploiting the capacity, and highly efficient es-timation schemes were proposed. The de-sign of the space-frequency code is currentlyunder investigation to round out the com-plete system concept.

The antenna arrays and the related radiofrequency devices must be calibrated for cer-tain smart antenna applications. In particu-lar, highly accurate antenna calibration is re-quired for high resolution direction-of-arrivalestimation algorithms, for null-steering beam-forming and for optimal down-link beam-forming at the cellular base stations. At thesame time, in commercial mobile communi-cation systems the overhead in terms of ra-dio resources and system components that isrequired for calibration must be as low aspossible. Therefore we have developed opti-mized robust calibration schemes. A detailedanalysis of the physical device properties hasresulted in a highly accurate calibration mod-el. Using this model we successfully demon-strated a nullsteering beamforming applica-tion with an experimental array antenna sys-tem in a laboratory environment at 5.2 GHzand at 60 GHz. For commercial system appli-

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cations we are developing calibration algo-rithms that are based on efficient mathemati-cal and computational methods.

Smart antennas in the 60 GHz range willplay an important role in future mobile com-munication systems at data rates of155 Mbit/s and above. The generation anddistribution of the microwave signals, and al-so beamforming, was carried out using opti-cal microwave technology. Constrainedbeamforming was accomplished by a newlydeveloped beamforming network based onSiO2/Si. The beamformer and the beamsteering algorithms were tested in an experi-mental system, and several experiments havebeen successfully carried out. The RF proper-ties of the phase and amplitude sections of a4-channel beamformer were measured at60 GHz using an antenna test setup with a1 x 4 phased array antenna. Error-free155 Mbit/s data transmission was achievedat various look directions of the antenna.This system presently uses the maximum-di-rectivity beamforming algorithm.

Optical millimetre-wave techniques forbeamforming array antennas are being in-vestigated and specific components are be-ing developed as part of the EuropeanOBANET project. This project is studying var-

ious coverage-area management strategiesand the technologies required to optimizetheir performance. Fixed and mobile broad-band radio access scenarios in the 40 GHzband are both being considered. An impor-tant issue for beamforming and beam steer-ing is the estimation of the direction of ar-rival. To investigate this problem, methodsusing pilot signals in a 40 GHz system are be-ing implemented at HHI, and digital signalprocessing is being used to evaluate them.

The beamforming and MIMO techniquescurrently being investigated lead to a drasticreduction of transmitter power, which great-ly eases the electromagnetic interferenceproblem. The reason for this is that the trans-mitter power with beamforming is concen-trated in the strongest paths between thetransmitter and receiver, which saves a con-siderable amount of RF power compared tonondirected emission. MIMO systems offerboth diversity gain and multiplexing gainover single-input single-output (SISO) sys-tems. These gains translate into drastically in-creased capacity, which can be used eitherto transmit more information without in-creased power or to save power at constantdata rates.

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Electronic Imaging Technology forMultimedia

Topics and Results

The R&D contributions of the HHI to thisresearch area are in the domains of Imageand Video Processing, Coding, and Transmis-sion as well as Interactive Multimedia Appli-cations.

Image Processing

The HHI activities in image processing areconcentrated on signal processing, codingand transmission of video services in variousapplications, on the design of VLSI compo-nents, and on system integration. A widerange of image formats, from very low reso-lution for narrowband video communicationup to high resolution for multimedia services,are supported. Typical applications includemultimedia communication over the internetor mobile networks, interactive multimediaservices, broadcast and communication ser-vices, and studio applications. Another im-portant topic is 3D signal processing for im-mersive systems, such as immersive telecon-ferencing or immersive TV.

As far as hardware projects are concerned,the development of architectures for futuremultimedia terminals is the central activity,with the focus on key components for 3Dgraphics, compositing, MPEG encoding anddecoding, and format conversion.

One emphasis was on the collaborativeproject Interoperability for Video Communi-cation over Distributed Networks (INVINET),which was sponsored by the Federal Ministryof Education and Research (BMBF). The maingoals of this project were the developmentof basic technologies for IP-based video com-munication, especially for mobile networks,and of interactive services over these net-works, particularly those using virtual envi-ronments. Important topics were the newcompression standard H.264/AVC that is be-ing jointly developed by ISO/MPEG and ITU-T/VCEG, the development of an authoringtool based on MPEG-4 for the creation of 3Dscenes, and a 3D compositor for MPEG-4.• Dr. Wiegand of HHI has been appointedco-chair of the Joint Video Team (JVT), a jointproject of ISO/MPEG (Moving PicturesExperts Group) and ITU-T/VCEG (VideoCoding Experts Group). The JVT is develop-ing the new H.264/AVC coding standard. Hehas also been appointed as the editor of

H.264/AVC and also as the editor of DVB ex-tensions of H.264/AVC.• HHI continues to integrate and support theofficial H.264/AVC reference software.• The superior rate-distortion performanceof H.264/AVC in all application areas hasbeen demonstrated by HHI’s image process-ing department at various exhibitions, in-cluding IFA and IBC. Recognition of HHI’s ex-pertise in video compression can be seenfrom the amount of industry funding ac-quired in this area.• The development of the HHI MPEG-4 play-er containing a 3D compositor has been con-tinued and new applications have been im-plemented. An interactive streaming systemfor high-resolution panoramic views was de-monstrated at IBC 2002 in Amsterdam. Thisapplication exploits the existing MPEG-4player and uses BInary Format for Scenes(BIFS nodes to represent cylindrical panora-mas. The user can freely navigate through apre-recorded environment and look at ob-jects from arbitrary viewing directions. Thehigh resolution texture of the scene is storedat the server, subdivided into small patches,and streamed on request over a network.Visibility nodes assure that only the currentlyvisible information is transmitted, which alsoenables the use of such a player on small de-vices with limited storage capacity. The sys-tem has also been shown at the MediaStreaming workshop in Berlin and the FKTGconference in Zurich.• The development of 2D and 3D authoringtools for MPEG-4 BIFS has been finalized anda complete authoring-player system conform-ing to MPEG-4 is now available.

Traffic due to multimedia streaming overIP networks (mobile, wireless, and wired) issteadily rising. However, so far there is noopen and standardized end-to-end multime-dia streaming solution with competitive per-formance to proprietary solutions. To ad-dress this problem, HHI’s image processingdepartment is developing, jointly with FhG-IIS-A and FhG-FOKUS, an Open MultimediaStreaming Architecture (OMSA). The OMSAproject is sponsored by BMBF. The main goalof this project is the specification, implemen-tation, and standardization of an open end-to-end solution for multimedia streaming.• As a starting point, the OMSA project hasbeen aligned with the specification of theInternet Streaming Media Alliance (ISMA),which is a non-profit corporation formed by34 companies to provide a forum for the cre-ation of specifications that define an interop-

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erable implementation for multimedia stream-ing IP networks.• HHI has implemented the ISMA v1.0 speci-fication and has further extended it byH.264/AVC. Live streaming has been demon-strated with a competitive rate-distortionperformance, compared to all existing multi-media streaming solutions. HHI’s expertise invideo streaming has also been recognized interms of the industry funding acquired in thisarea.

Processing methods for image analysis andclassification have been developed by HHI’simage processing department as part of theMPEG-7 standardization process. These meth-ods are being further explored in the BBIproject (sponsored by BMBF) for enhancedvideo compression using the analysis infor-mation for image and video synthesis. Thevideo synthesis is applied to textures, whichapparently require many bits but which donot need to be reconstructed exactly. Theserandom textures include water, clouds, sand,trees, flowers, walls, etc. The goal of the BBIproject is to develop an automatic analysis-synthesis tool that reduces the bit rate, butkeeps a similar subjective quality, wheneverthe source material contains such randomtextures.• The analysis package started with the clas-sification of textures in images using variousMPEG-7 descriptors. The image-based meth-ods are further extended to video analysis byusing MPEG-7 parametric motion descrip-tors.• The synthesis package started with hand-segmented video frames to develop a newvideo synthesizer and to demonstrate thepotential performance of the approach. Firstresults indicate that substantial bit-rate re-duction can be obtained with very small sub-jective impairments if the video contains ran-dom textures.

The development and verification of tech-nologies that are required for new function-alities in mobile multimedia and internet sys-tems is of crucial importance. Such function-alities have been identified in ISO-MPEG, andthe MPEG-4 standard will be the basis for im-age and sound compression in future multi-media systems. These new functionalities, in-cluding content manipulation, content-based scalability and content-based access,are obtained with coding algorithms that arevery efficient and robust against transmissionerrors.• A final version of an e-commerce systembased on MPEG-4 software components has

been developed for the IST project SoNG(Portals of Next Generation), in cooperationwith T-Nova and Blaxxun Interactive. Theclient part of this e-commerce system isWeb-based and consists of a generic, appli-cation-unaware MPEG-4 compositor that canbe embedded in an HTML page, along withapplication-specific Java code and modulesfor MPEG-4 video encoders and decoders.The core of the application logic is imple-mented in downloadable Java code modules,which communicate with the MPEG-4 com-positor using the standard-compliant MPEG-JAPI. A content provider can update the con-tent and logic of the e-commerce system bychanging BIFS, Java or JavaScript code on theHTML/MPEG-4 server. The video encoderand decoder facilities of the system allowcustomers to contact sales and support staffusing audio or video communication. Thissystem was demonstrated at IBC 2002.

Computer graphics and image processingtechnologies have reached a state that allowsthe development of novel multimedia appli-cations and services. The new challenge inthe field of television, electronic cinema andmultimedia applications is called immersivetelepresence, in which users should feel thatthey are immersed in the scene. Large dis-plays with high resolution (similar to cinema,IMAX or CAVE projections) in VR applicationsare required. In this context the current ac-tivities of the image processing departmentare concentrated on three major applica-tions: 3D videoconferencing, digital cinemaand 3D-TV.

A new videoconferencing concept hasbeen proposed by the BMBF funded projectITI (Immersive Tele-Presence in the Internet),in close collaboration with the European ISTproject VIRTUE (Virtual Team User Environ-ment). It is the first mixed-reality approachto immersive 3D videoconferencing in theworld. The seamless transition between a realworking desk in front of the display and thevirtual conference table in the screen givesthe user the impression of being part of anextended perceptual space. The remote par-ticipants are rendered seamlessly and withthe correct perspective views in the virtualconference scene to achieve most natural re-production of the attributes that are particu-larly important for human-centred communi-cation (eye-contact, gaze direction, bodylanguage, gestures, etc.). The following arethe major achievements so far:• The complete 3D video processing chainfor the videoconference system has been im-

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plemented and tested under real-time condi-tions. It is now running successfully as an ex-perimental prototype platform, and includestechnologies for multi-view capturing, fore-ground/background segmentation, trackingand segmentation of hands, disparity estima-tion, 3D view combining, 3D warping, 3Dview synthesis using image-based rendering,vision-based head tracking, hybrid 3D com-position, and rendering of the virtual confer-ence scene.• The prototype platform is based on a con-ventional PC architecture, augmented bymulti-DSP VPS (VIRTUE Processor Station)boards, which were developed in the ImageProcessing Department of HHI. The objectiveof the VPS board is to achieve real-time 3Dvideo processing with state-of-the-art PCtechnology. When combined with an SDI in-terface board, up to four video streams canbe captured and processed simultaneouslywithout loading the PCI bus. Cascaded VPSboards can be used to set up an arbitrarymulti-processor topology for complex 3Dvideo processing applications.• A second-generation prototype has beendeveloped within the ITI project. The objec-tive of this re-design is to achieve full MPEG-4compliance, including BIFS scene representa-tion, MPEG-4 video encoding and decodingand DMIF conference management. The 3Dvideo processing chain will be optimised toreduce complexity and the number of DSPboards. ITI will target the problems of audiodelay and echoes, using an integrated audiocapturing, rendering and echo cancellationsystem based on low delay ASIO interfaces,which are generally used in professional au-dio recording equipment.• The prototypes will be demonstrated tothe public for the first time at an ITG work-shop on “Immersive Communication andBroadcast Systems” (ICOB’03) in January2003 in Berlin, jointly organised by HHI pro-ject ITI and the IST projects VIRTUE, ATTESTand Eye-2-Eye. A further demonstration isplanned for CEBIT 2003 in Hannover.

A similar 3D video conferencing approachis being investigated in the newly establishedBMBF-funded VisionIC project. Together withInfineon AG, Munich, an “Advanced Video-phone” is being developed that allows multi-ple participants to communicate in a sharedvirtual environment. In contrast to VIRTUE,the system is entirely avatar-based and tar-gets extremely low bit rates (a few kilobitsper second). For the description of the virtualscene and the animation of the characters,

the MPEG-4 syntax is used to achieve stan-dard-compliant virtual conferencing. Sinceno video stream but only 3D motion and an-imation data are transmitted, even low band-width channels, such as wireless channels forportable devices and PDAs, can be support-ed. A first demonstration of this system isplanned for CEBIT 2003 in Hannover.

Digital Cinema (D-Cinema) is currently at-tracting increased attention. In contrast tothe video, audio and internet industries, inwhich signals are now processed entirely dig-itally, the cinema industry seems to have lostthe connection to modern technology. Onereason for this stagnating development is theunavailability of several key components be-cause of their very high technological re-quirements. To close the gap between tradi-tional cinema and the new digital multime-dia evolution, the D-Cinema project wasstarted. It aims to find out how to use digitaltechnologies and their advantages in cine-ma. Digital cinema will also be able to showlive events such as the Olympic games orgreat performances, which is a completelynew service. In this context the image pro-cessing department of HHI is mainly workingon the distribution and receiving part of thedigital cinema system chain.• A prototype system for the immersive pro-jection of ultra-high definition vision hasbeen developed for digital cinema applica-tions. The system allows the modular config-uration of multiple synchronised projectors,each working in HD resolution. For immer-sive projection purposes, the different HDviews are seamlessly stitched together.• A new method based on MPEG-2 for theprecise synchronisation of the various projec-tors has been developed. This synchronisa-tion procedure is completely modular andenables the unrestricted cascading of multi-ple projection arrays.• The prototype has been demonstrated atthe CeBit Exhibition 2002 in Hannover, atthe 20th FKTG-Meeting in Zürich, and at theIBC fair 2002 in Amsterdam.

3D-TV is expected to be the next majorevolution in the history of television. So far,almost all approaches are based on the basicidea of “stereoscopic” video; i.e. the captur-ing, transmission and display of two separatevideo streams, one for each eye. The maindrawback of these systems is their inflexibilityin terms of depth reproduction as well as dif-ferent display technologies and viewing con-ditions. A new approach, currently under de-velopment within the IST project ATTEST,

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tries to overcome these restrictions and pro-vide a more flexible system. The concept isbased on the joint transmission of video andassociated depth information. Monoscopicor stereoscopic “virtual” views of the sceneare generated by means of depth-image-based rendering techniques. The followingresults have been achieved so far:• The ATTEST 3D-TV scenario was proposedfor evaluation by the newly established MPEG3D Audio/Visual Ad-Hoc group. It was accept-ed as an interesting future 3D technology.• First experiments on the coding of depthinformation have been carried out by AT-TEST and MPEG. Preliminary results suggestthat only minor extensions to the currentMPEG standard are necessary to enable a3D-TV broadcast service based on the AT-TEST concept.• A 3D renderer capable of synthesisingstereoscopic views for different 3D displays iscurrently under development. The systemsupports head-motion parallax viewing andwill provide the 3D-TV user with the possibil-ity of adjusting the depth perception to meethis or her own preferences. It will also sup-port various composition algorithms (CRTspace only, CRT plus viewer space, or zero-parallax setting defined by the contentprovider).

Mobile multimedia is foreseen to be one ofthe major applications for the upcomingbroadband mobile networks such as UMTS.Besides pure streaming applications for uni-directional communication, bi-directional ap-plications such as video teleconferencing andmultimedia messaging will become moreand more popular.• To fulfil the special requirements of multi-media applications in mobile environmentsin terms of power dissipation and processingpower, a dedicated MPEG-4 video codecASIC has been implemented in cooperationwith an industrial partner. This ASIC, which isbased on several hardware acceleration com-ponents and an embedded processor, is acomplete single chip solution for MPEG-4video coding and decoding, and has pictureresolutions up to QCIF at 15 fps and datarates up to 128 kbit/s. The hardware-soft-ware partitioning was based on the results ofintensive profiling runs using optimisedMPEG-4 video codec software for the target-ed ARM processor core. The whole softwarewas implemented from scratch using C. Thesoftware supports MPEG-4 simple profile atlevels 0, 1, 2 and 3, which differ slightly fromeach other in the tools used. From the speci-

fications of the target application, the high-est supported bitrate of 128 kbit/s for QCIFresolutions with frame rates of up to 15frames/sec was chosen for the profiling runs.Based on this analysis, the deblocking andderinging filters as well as the colour conver-sion and image scaling sections were chosento be dedicated hardware blocks in the de-coder. On the encoding side, the motion es-timation was identified as a candidate fordedicated hardware implementation.

Audio is an important feature of manyMPEG-4 application projects. Due to itsmany refinements, MPEG-4 AAC (AdvancedAudio Coding) is the most efficient audiocompression technique known at present.This standard supports sampling rates from8 kHz to 96 kHz and provides audio of nearCD quality at a very low bitrates (64 kb perchannel). The AAC standard handles up to48 channels in one bit stream, and is there-fore suitable for any multichannel applica-tion. MPEG-4 AAC can be used in a widerange of applications such as home cinema,internet audio and hand-held players/rec-orders.• The availability of powerful DSP and RISCprocessors enables the implementation ofcomplex audio codecs on dedicated modulesin hand-held devices. MPEG-4 AAC audio en-coders and decoders for real-time applica-tions have been implemented on differentplatforms: Texas Instruments DSPs, RISCprocessor StrongARM, and MIPS32 4Kc. Theperformance and low power consumptionsof these processors enable the implementa-tion of modules for battery-powered hand-held systems.

Novel multimedia terminals and interactiveapplications need the simultaneous displayof several sources on one display. Under theframework of the KOKON project, funded byBMBF, the DUMA (multi-standard displayunit) board was developed as a hardwareplatform for applications requiring simultane-ous display of different videos and computer-generated images. Composite (FBAS) orcomponent analogue and digital (DVI) sig-nals are supported as input standards. Thesystem is able to display up to four real-timevideo images or pictures on a high-resolutionmonitor using digital (DVI) or analogue(RGB) inputs. The windows can be indepen-dently positioned, alpha-blended, or overlaidwith other windows. A hardware-supportedcursor can be used for navigation purposes.• The implementation of the system on anFPGA platform, using a StrongARM module

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for processing control, has been completed.The system will be presented at an HHI work-shop in March 2003.

Conversion from one video format to an-other (e.g. TV to HDTV) and image enhance-ment are two very important techniques foradvanced multimedia terminals. In the fieldof format conversion, HHI has establishedtrend-setting know-how and expertise in nu-merous research activities. The motion com-pensating image sequence conversion algo-rithm (HiCON), developed by HHI, providesconversion between different image sequenceformats. It performs de-interlacing while pre-serving full spatial resolution. Image rateconversion is accomplished with sufficientmotion portrayal for high-quality image ap-plications such as digital cinema. This is thebasic requirement for the optimal flicker-freeand judder-free operation of high-end dis-plays. HHI performed architectural studies onthe basis of motion-compensated video im-age conversion techniques. Both a softwarerealization and a single chip realization havebeen developed.• The software implementation is suited forthe conversion of all standard video andgraphic formats. It is projected as an off-lineplatform-independent software tool, but sofar is optimised for win32 applications. Thissoftware will by marketed by an industrialpartner.• The design of a single–chip implementa-tion for real-time applications in standard TVand HDTV is complete. The netlist has beensimulated and may be transferred to silicon.This design is the basis of several cooperativeindustrial ventures planned for 2003.• Several image enhancement algorithmsthat reduce blocking and ringing artefactscaused by standard codecs (e.g. MPEG-2)have been investigated. A real-time deblock-ing filter has been implemented and opti-mised on the Trimedia DSP.

Advanced multimedia applications are be-coming more and more complex. Hencereusable, modular and well-designed soft-ware must be used to create stable, main-tainable and supportable applications.• During the last year, the Image ProcessingDepartment established software design pro-cedures that ensure cost-effective softwaredevelopment, that protect HHI’s intellectualproperty, and that reduce the time to mar-ket. A project group was founded to create adocumented, guided and supported processfor the generation of applications and li-braries that meet the above requirements.

Interactive Media – Human Factors

The HHI carries out R&D in the area of in-teractive multimedia services and new me-dia, concentrating on user friendly multime-dia applications, interaction technologies andmultimedia terminals.

The focus of the work is on autostereo-scopic display technologies, novel and trend-setting technologies for 3D desktop comput-ers, the development of innovative 2D and3D interaction techniques for man-machinecommunication, virtual telepresence and tele-immersion applications, methods for datasearch and data visualisation, and intelligentagent-based information management anduser guidance. These main themes are ex-tended by both fundamental and appliedwork in the area of usability engineering,with special emphasis on human factors con-straints.

The autostereoscopic display developmentsconcentrate on approaches that do not re-quire the user to wear special glasses whenviewing natural or computer generated 3Dimages or videos. Applications of this tech-nology are in such diverse areas as 3D tele-phony and video conferencing, 3D TV, 3Dmultimedia desktop computing, mixed-reali-ty worlds, telepresence, telework, telesuper-vision, vehicle navigation and driver assis-tance technology, CAD/CAM, 3D computergames, medicine, and biology. The work inthese areas includes the development ofsmall to large flat panel autostereoscopic dis-plays for one or more viewers, as well aslarge format front or back projection displaysusing parallax barrier screens, lenticular lensscreens and field lens technologies. Proto-types of these developments were intro-duced to the public this year at the CeBIT2002 in Hannover and at several smallertrade fairs and exhibitions.• A high resolution single-user autostereo-scopic 20.1’’ flat panel display for use in theCAD/CAM area was developed. This displayprovides (2 x 512) x 1280 pixel resolutionand does not require mechanical tracking ofthe lenticular screen – instead, the entiremonitor is mounted on a mechanical track-ing platform so that the image plane cantrack the user’s head movements (Face-to-Face 3D Display concept). Optionally, an IRhead tracker in combination with pixelswitching technologies gives the user track-ing comfort when moving in front of thescreen. Based on a license agreement withthe HHI, A.C.T. Kern GmbH & Co. KG, a

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renowned manufacturer of professional dis-plays, has recently started production andsales of this novel display system.• We have developed a special 2D/3D com-patible version of this type of display calledCabrioScreen. The CabrioScreen is a 3D add-on, including a removable lens plate and ahigh precision IR head tracker, that allowsthe user to temporarily convert a common20.1’’ NEC LCD display into a high-resolu-tion autostereoscopic display.• Various newly emerging mixed-reality ap-plications, e.g. in the automotive sector, re-quire a wide screen display, in order to showextended portions of a large system in natur-al size. On the other hand, designers want ameans for precise 3D visualization and ma-nipulation of selected parts of the compo-nents under development. For this purpose,we have developed the Hybrid Display, aunique precision 3D display embedded in alarge surrounding 2D display area. The dis-plays share a joint 3D data space. With a sim-ple hand gesture, detected by a video track-er, the user can select a part of interest fromthe 2D area and move it focus on the 3D dis-play (gesture-based drag & drop operation3D), where it will float 20 cm in front of thedisplay screen. The user may then touch itlike a real object. The current finger positionis remotely detected by a stereo hand trackerembedded in the desktop. Optionally, a forcefeedback device provides tactile feedbackwhen touching the virtual object with a (sim-ulated) tool.• The Accommodation Display is a novel au-tostereoscopic single-user display based on aspecial 3D technology using a large-diameterfield lens. With this display it is possible tocreate an aerial stereo image plane appear-ing at any position, either in front of the dis-play (e.g. within reach) or behind the displayscreen. The display has outstanding resolu-tion, brightness and contrast and minimalcrosstalk (far below the visibility threshold). Itis particularly useful for mixed-reality applica-tions, since it is possible to make the accom-modation distance of a virtual object perfect-ly match the distance of a real object (e.g. ofa tool used to manipulate the virtual object).This contrasts with conventional 3D tech-niques, which are known to produce con-flicting accommodation stimuli when userstry to directly touch 3D objects appearingstereoscopically in front of the display.• A large format 40’’ autostereoscopic backprojection display with high resolution((2 x 1000) x 750 pixels) was developed for

applications in multimedia desktop comput-ing. This monitor features mechanical track-ing of the parallax barrier screen.• New developments focus on a combined2D/3D display with lenticular lens trackingfor 3D TV and kiosk applications. In this casethe 2D area is designed as a touch screen,which may for example find application as auser interface for searching for additionalprogram information over the internet (TVapplication) or for browsing an electroniccatalogue (kiosk application). We have alsostarted to extend the Accommodation Dis-play principle to the development of virtualand mixed-reality displays for mobile applica-tions.• A video-based head tracker compatiblewith a range of low-cost as well as high-pre-cision cameras was developed so that theHHI displays can be used without specialglasses.• A recently patented IR head tracker for thesame purpose provides the same functionali-ty at reduced cost and with reduced sensitivi-ty to lighting conditions.

In recognition of the need to develop newconcepts and technologies that point theway to the 3D desktop computer of the fu-ture, the work at the HHI concentrates onthe vision of a computer with intelligentman-machine interfaces. To make operationeasier for the user, prototypes of desktopcomputers were developed that present in-formation in a clearly arranged and sufficientform using a 3D display and suitable 3D visu-alisation methods. The wishes of the user areanticipated by innovative multimodal inter-action and agent technologies, thus enablingsimple and intuitive operation in interactiveapplications.

An advanced prototype of an intelligentand ‘seeing’ 3D desktop computer that over-comes the disadvantages of the commonwindows desktops and allows novel forms ofuser interaction was implemented and shownpublicly at various trade fairs and exhibitions.• The development of a novel 3D visual op-erating system and suitable editors gives thedesktop computer a simple and clearlyarranged representation of multimedia infor-mation, together with a simple means forthe user to interact with it. In contrast toconventional windows-based desktops, thisoperating system is object oriented and canlayer information in the depth dimension.• A 20’’ high-resolution autostereoscopicdisplay that was developed by the HHI wasused for the prototype of a 3D computer

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that allows the visualisation of multimediaobjects arranged in the depth dimension.These objects are generated and managedby the 3D operating system. Because of theautostereoscopic representation, the user cansee the objects and information stacked indepth layers, and can view them from differ-ent sides by moving his or her head (motionparallax).• A novel workbench system based onWindows XP allows simple user interactionwith multiple 2D and/or 3D display screensof various formats in a joint data environ-ment. The HHI Workbench accepts inputfrom multimodal interface devices, such asthe head, eye or hand movement trackersthat have been developed in our labs, andwill be used in connection with the HybridDisplay for mixed-reality applications.• An improved video-based method formeasuring the user’s head movement andgaze direction that was developed at the HHIrelieves the user of the need to wear eitherhead markings or special glasses. We haveimplemented a user-friendly (automatic) ini-tialization and calibration process for bothtrackers.• A stereo video hand tracker was developedfor novel man-machine interaction applica-tions. This device is able to track hands orfingers, so that the user can point to and in-teract with virtual objects floating in front ofa 3D display screen. Based on software com-puter vision algorithms, this technology per-forms tracking in real time on general pur-pose PCs.• An interface agent can recognise what theuser is viewing and can then autonomouslyinitiate appropriate actions (visually con-trolled graphics). In this way the representa-tions of the displayed objects can bechanged in a manner that is adapted to theuser (e.g. the depth representation of theobjects can be changed to model the depth-of-focus behaviour of the human visual sys-tem). Also, the user can initiate actions bymeans of gaze control.• A prototype system for teleworking in 3Dwas developed and presented to the publicat the IFA 2001 exhibition in Berlin. It allowsteleworkers to jointly develop and manipu-late 3D objects. The components of this sys-tem include an autostereoscopic 3D display,a visual 3D operating system, a camera thatsenses head and hand position, and a systemto determine the gaze direction (for gaze-controlled interaction).

Research in the area of algorithms for 2D

and 3D image processing was carried out inorder to equip future generations of multi-media terminals and desktop computers witha large degree of intelligence and new formsof man-machine interaction. Applications arein the areas of 3D desktop computing, tele-working and telepresence. The work in thisresearch area concentrates on user recogni-tion, object recognition and tracking, 3Ddepth estimation, 3D intermediate view gen-eration, and head, gaze and hand-gesturetracking.• A video-based head tracker was developedwith the aim of presenting users of an au-tostereoscopic display with views of 3D im-ages from various directions. The tracking al-gorithm responds reliably to the smallestchanges of head position, even in difficultlighting conditions, and passes the measure-ments to a head tracking display or to anoth-er device controlled by the head position.The algorithms work in real time and wereimplemented under Windows 2000 and XP.The tracker software can be used in connec-tion with a wide range of cameras usingstandard WfV and WDM video drivers as wellas special drivers delivered with the camera.Several head-position data output formatsare supported (DCOM, RS232, UDP). Meas-urement rate is up to 120 Hz, so that there isno noticeable delay.• We have developed and recently patenteda multiple-cornea-reflex technique to mea-sure the gaze direction. When used with thevideo head tracker, this technique allows freehead movements. Gaze-direction measure-ments are also being investigated for possi-ble use as input signals for interactive pur-poses in future desktop computers (visuallycontrolled graphics).• A new work item dedicated to peoplesensing technologies was initiated in 2001.The purpose of this research effort is to equipsystems and devices with the ability to detectpeople in front of devices or in their sur-roundings. Of particular interest are the iden-tification of users, the sensing of their inter-actions with others, the sensing of their emo-tions or communication readiness, and therecognition of their gestures or general in-tentions.

Informal communication is an importantaspect of human communication. This in-cludes spontaneous and mostly confidentialconversations, e.g. on the fringes of confer-ences, during coffee breaks or at otherchance meetings. Since this form of commu-nication has a positive significance for the in-

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dividual worker as well as for the organiza-tion, means of providing technical supportfor informal communication among distrib-uted work groups (for either telework or tele-cooperation) are being investigated. A ques-tionnaire to potential users of telecoopera-tion systems showed that informal commu-nication in many areas connected with workis viewed as absolutely essential.• To determine the essential features neededfor telecooperation systems to support infor-mal communication, various field studieswere carried out using a chat system, a chatsystem extended by still images, and a virtualenvironment. The results showed that infor-mal communication is possible with text-based communication systems, but that theyshould be augmented by indicators of thedegree of communication readiness of po-tential communication partners.• For telework applications, the telepresenceof a work group was simulated using a virtu-al office environment generated by comput-er graphics. Each participant of the teleworkgroup, including his or her position and ac-tions in space, was given a computer graphicrepresentation (avatar). This concept ap-peared to be promising, especially for infor-mal communication among teleworkers. Itdelivered a high degree of telepresence witha sufficient degree of privacy protection.• A PreMon Awareness Monitor was devel-oped that senses whether a teleworker is pre-sent in front of the monitor, and whether heor she is working or participating in oralcommunication. Speech and vision sensorsare used in this monitor.• In view of the increasing importance ofmobile teleworkers, the PreMon Awarenessvisualization system was also adapted for usein mobile phones based on the WAP proto-col.

Technology that allows users to search andnavigate through large image data bases isattracting increasing attention in researchand development. Work was carried out inthe context of the MPEG-7 standardizationactivities, with particular focus on adaptiveand learning algorithms that are trained forthe preferences of the particular user andthat can search for images based on visualsimilarity measures. New philosophies andalgorithms were developed for clusteringand displaying image content based on hu-man visual criteria.• Human factors studies were initiated to un-derstand how human viewers perceive andcategorize information in images.

• 3D visualization tools were developed thatenable the user to search and navigate intu-itively through an image database. This ap-proach is based on a new relevance feedbacktechnique.• A cognitive map of the database content,similar to a city street map, allows the user tonavigate through an image database using acoarse-to-fine concept.• A variety of MPEG-7 conformant descrip-tors that can be used to search for imagesbased on image content rather than text an-notations were developed and implemented.• Algorithms for the automatic classificationof images into pre-defined categories weredeveloped.• A new similarity measure for segmentedimages was developed. This method takes in-to account colour, edge, texture and shapeproperties of image segments as well as theirrelative positions.

In a new research effort initiated in 2002,we are extending this work to the search andarchiving of digital video content. In particu-lar, we are developing methods for the seg-mentation of video sequences, algorithms forthe MPEG-7 conformant extraction of videodescriptors, algorithms for semantic classifi-cation of video sequences as well as a userinterface for intuitive visualization of videodata spaces and content searching. This re-search is performed in cooperation with na-tional and European consortia, includingpartners from universities and relevant indus-trial enterprises.

Another new research project is focusingon the development of a novel platform tosupport mobile services for citizens. This workaims at achieving the full functionality of thecommon stationary services. Among otherthings, the project is conducting research in-to the security and usability aspects of themobile hardware, software and data trans-mission components. The system will be test-ed under controlled conditions in the labora-tory as well as in extended field trials. TheSenate of Berlin is one of the partners in thisproject.

Competencies

3D image and video processing

Image and video coding (MPEG-1/2/4,H.26x, wavelet and model based)

Image and video analysis, computer vision

Image and video synthesis, computer graph-ics

Multimedia transmission (IP, mobile net-works, DVB)

Hardware design and implementation ofmultimedia systems (video, audio, graphics)

ASIC and IP design

Image and video enhancement (format con-version, noise reduction, deblocking, dering-ing)

Immersive image reproduction techniques

Multiview capturing and display systems

Software design and implementation of mul-timedia systems

Autostereoscopic 3D and mixed-reality dis-plays for desktop and mobile applications

Human-computer interaction

User interface development, including 3D

GUI design and techniques for multimodalinteraction (head tracking, gaze tracking,hand tracking and gesture recognition)

Application development with Visual C#,Visual C++ and Java; expertise in multimediaapplication programming using DirectX

Usability engineering

Image and video segmentation, feature ex-traction, classification, retrieval and archiving

Video-based pattern recognition and pho-togrammetry methods

User and object sensing and tracking meth-ods, including inside-out and outside-in opti-cal tracking techniques

Analysis of human sensory and sensorimotorfunctions in relation to multimedia applica-tions

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39H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

Project ManagerphoneeMail

Godehard Walf+49(0)30-31002-455walf@hhi.de

Erwin Patzak+49(0)30-31002-514patzak@hhi.de

Godehard Walf/Jürgen Saniter+49(0)30-31002-455/-288walf@hhi.de/saniter@hhi.de

Ernst-Jürgen Bachus+49(0)30-31002-586bachus@hhi.de

Ernst-Jürgen Bachus+49(0)30-31002-586bachus@hhi.de

Ernst-Jürgen Bachus+49(0)30-31002-586bachus@hhi.de

Ernst-Jürgen Bachus+49(0)30-31002-586bachus@hhi.de

Ernst-Jürgen Bachus+49(0)30-31002-586bachus@hhi.de

Ernst-Jürgen Bachus+49(0)30-31002-586bachus@hhi.de

Klaus Langer +49(0)30-31002-457 langer@hhi.de

Thomas Hermes+49(0)30-31002-455walf@hhi.de

R & D PROJECTS

Project

Photonic Networks

KomNet System Integration Office

Optical Technologies in Motion forthe IST Programme

Innovation of Photonic and MobileCommunication Network for theBroadband Internet (TansiNet ON)

DWDM and IP

Application of Distributed RamanAmplification for WDM Networks

System Aspects and Tests forCityring Networks

Design of Switchable OpticalNetworks

Development of OptimisedExpanding Strategies forWavelenght Division MultiplexSystem for Applying a maximumTransmission Datarate in ModernFibre Infrastructures

Control Modulation Technique forClient-Independent PerformanceMonitoring and ChannelIdentification in Transparent Optical Networks

Broadband Optical Access- andInhouse Networking – NetworkArchitecture and Protocols (ON)

Frequency Selective IntegratedWDM Receiver

Provider of Grant/ ContractorPeriod

BMBF/Industry(KomNet)5/98 – 4/02

EU5/00 – 4/03

BMBF6/00 – 5/03

HHI10/00 – 12/02

DFG3/02 – 5/04

BMBF/Industry(KomNet)9/98 – 12/02

BMBF(UMTS)4/01 – 3/03

BMBF(MultiTeraNet)10/02 – 9/04

DFG10/02 – 9/04

BMBF(MultiTeraNet)10/02 – 9/05

DFG8/99 – 7/02

Industry /KomNet7/99 – 4/02

BMBF8/99 – 7/02

DFG5/00 – 4/04

DFG4/98 – 6/04

BMBF8/00 – 7/03

DFG3/00 – 2/03

HHI8/99 – 7/02

Industry4/00 – 12/02

Industry7/01 – 3/02

BMBF(MultiTeraNet)01/02 – 9/05

Industry11/01 – 3/03

BMBF1/01 – 12/03

State of Berlin9/02 – 8/05

Industry4/02 – 3/04

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Hans-Georg Weber+49(0)30-31002-443hgweber@hhi.de

Bernd Sartorius+49(0)30-31002-508sartorius@hhi.de

40 Gbit/s OTDM for KomNet

Optical Time Domain MultiplexTechnique for the Internet of theFuture

Optical Sampling of High BitrateData Signals

Gain-Clamped Optical Amplifier inFibre-optical Transmission Systems

Active Resonant Grating-WaveguideStructures for Rapidly TuningSemiconductor Lasers with noMoving Elements

Saturable-absorber Switch

Technological Developments forHigh Speed OTDM TransmissionSystems

160 Gbit/s TransmissionTechniques

High-bitrate Optical SignalProcessing

Optical Time Division MultiplexTechniques for 160 Gbit/s and 640 Gbit/s

Transmission Techniques in a SingleChannel for Datarates of 160 Gbit/sand beyond

Integrated Circuits for a ETDM-Datatransmission in a 80 Gbit/sSingle Channel

Compression Techniques andSystem Investigations

Transfer 40 GHz Optical Clock

40 H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

41H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

BMBF2/01 – 7/03

EU9/01 – 8/04

BMBF7/01 – 6/04

DFG2/01 – 6/02

HHI1/98 – 12/02

Industry11/01 – 6/04

Industry1/01 – 3/02

State of BerlinIBB1/02– 12/03

BMBF/Industries(KomNet)6/98 – 4/02

BMBF4/00 – 3/03

BMBF10/00 – 9/03

BMBF(MultiTeraNet)10/02 – 9/06

BMBF/VDI2/02 – 1/05

DFG11/01 – 10/03

Bernd Sartorius+49(0)30-31002-508sartorius@hhi.de

Bernd Sartorius+49(0)30-31002-508sartorius@hhi.de

Bernd Sartorius+49(0)30-31002-508sartorius@hhi.de

Bernd Sartorius+49(0)30-31002-508sartorius@hhi.de

Michael Schlak/Bernd Sartorius+49(0)30-31002-407/-508schlak@hhi.de/sartorius@hhi.de

Michael Schlak +49(0)30-31002-407schlak@hhi.de

Martin Möhrle+49(0)30-31002-724moehrle@hhi.de

Martin Möhrle+49(0)30-31002-724moehrle@hhi.de

Helmut Heidrich+49(0)30-31002-538heidrich@hhi.de

Helmut Heidrich+49(0)30-31002-538heidrich@hhi.de

Helmut Heidrich+49(0)30-31002-538heidrich@hhi.de

Helmut Heidrich+49(0)30-31002-538heidrich@hhi.de

Helmut Heidrich+49(0)30-31002-538heidrich@hhi.de

Helmut Heidrich+49(0)30-31002-538heidrich@hhi.de

High-frequency Selfpulsation ofMulti-section DFB Laser

Terabit per Second OpticalTransmission Systems Based onUltrahigh Channel Bitrate

Optical 3R Regeneration forAsynchronous IP Networks

Design of Switching Characteristicsin Dispersive Q-switchSemiconductors

Technical Development for OTDMDemultiplexers

160 Gbit/s 3R Regenerator

Development of DFB-BH-Lasers

Development of Future InP-basedLaserdiodes

Low-Cost Transceiver-PIC for theAccess Network

Innovative Lasers and Filters on InPUsing Ring Oscillators

Monolithically IntegratedPicosecond Pulse Source

Hybrid Integration on SOI Basis/adapted Laser and SOA-OEICs

Planar Photonic Crystals inMaterialsystems with high IndexContrast

Realisation of high Order Optical Filters Using Active Coupled Microring Resonators

HHI1/02 – 12/02

MBI/HHI11/98 – 3/02

HHI7/99 – 6/02

DFG9/00 – 8/03

Land Berlin(TOB)10/02 – 9/05

BMBF4/00 – 3/03

HHI1/01 – 12/02

HHI6/98 – 04/02

BMBF(UMTS)5/01 – 12/03

BMBF(MultiTeraNet)10/02 – 9/05

State of Berlin(TOB)9/02 – 8/05

State of Berlin(TOB)9/02 – 8/05

HHI1/01 – 12/02

BMBF6/01 – 5/04

Jochen Kreißl+49(0)30-31002-525kreissl@hhi.de

Harald Künzel+49(0)30-31002-546kuenzel@hhi.de

Harald Künzel+49(0)30-31002-546kuenzel@hhi.de

Harald Künzel+49(0)30-31002-546kuenzel@hhi.de

Harald Künzel+49(0)30-31002-546kuenzel@hhi.de

Berndt Kuhlow+49(0)30-31002-448kuhlow@hhi.de

Berndt Kuhlow+49(0)30-31002-448kuhlow@hhi.de

Udo Niggebrügge+49(0)30-31002-550niggebruegge@hhi.de

Karl-Otto Velthaus/Herbert Venghaus+49(0)30-31002-645/-555velthaus@hhi.de/venghaus@hhi.de

Karl-Otto Velthaus +49(0)30-31002-645velthaus@hhi.de

Karl-Otto Velthaus +49(0)30-31002-645velthaus@hhi.de

Bernd Hüttl +49(0)30-31002-659huettl@hhi.de

Norbert Keil+49(0)30-31002-590keil@hhi.de

Norbert Keil+49(0)30-31002-590keil@hhi.de

BH-Laser for High Bitrates

Semiconductor Saturable Absorber Structures forFemtosecond demultiplexer

GaAs-Based 1300 nm Laser

Lattice-matched MBE-growth of(In,Ga)As/(In,Al)As- and(In,Ga)As/Al(As,Sb)-structures onInP for Intersubband Emitters

Intersubband Materials forUltrahigh Speed Optical Switches

Micro-Filter in Silica-on-SiliconTechnology for OpticalCommunication

Planar integrated Waveguide-network on Silica

Development of AdvancedTechnologies for UltrafastPhotoreceivers

80 Gigabit Modulator Module

Electro-optical Modulator for FutureCommunications Networks

Development of New Concepts,Structures and Technologies inProducing Modulators for 160 Gbit/s

Monotlithically IntegratedLightsources

AWG Based on Polymer

Integrated Optical Add/DropMultiplexer Based on PolymerTechnology

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43H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

BMBF(UMTS)4/01 – 12/03

Industry1/02 – 12/03

Industry11/01 – 12/03

Industry1/02 – 12/03

BMBF(MultiTeraNet)6/02 – 5/05

Industry7/02 – 12/03

BMBF(MultiTeraNet)10/02 – 9/05

BMBF6/00 – 5/03

HHI6/00 – 12/02

HHI6/00 – 12/02

DFG7/00 – 6/02

HHI9/00 – 12/02

BMBF11/00 – 12/03

BMBF5/00 – 4/02

Thomas Rosin+49(0)30-31002-221rosin@hhi.de

Wolfgang Schlaak+49(0)30-31002-519schlaak@hhi.de

Anagnostis Paraskvopoulos+49(0)30-31002-527Paraskevopoulos@hhi.de

Anagnostis Paraskvopoulos+49(0)30-31002-527Paraskevopoulos@hhi.de

Anagnostis Paraskvopoulos+49(0)30-31002-527Paraskevopoulos@hhi.de

Heinz-Gunter Bach+49(0)30-31002-503bach@hhi.de

Heinz-Gunter Bach+49(0)30-31002-503bach@hhi.de

Holger Boche+49(0)30-31002-540boche@hhi.de

Holger Boche+49(0)30-31002-540boche@hhi.de

Holger Boche+49(0)30-31002-540boche@hhi.de

Holger Boche+49(0)30-31002-540boche@hhi.de

Clemens v. Helmolt+49(0)30-31002-506helmolt@hhi.de

Clemens v. Helmolt+49(0)30-31002-506helmolt@hhi.de

Gerd Großkopf+49(0)30-31002-317grosskopf@hhi.de

Advanced Packaging Technologiesfor Highest Frequency Opto-Electronic Components

Development and Realization ofPhoto Detectors and Receiver –OEICs

Planar Selective Epitaxie

Development of New Lightsources;Production Processes and FibreCouplings

1400 nm Pump Laser Source forTDFA

Development of a Photoreceiver

High Rate Optical Receiver for80/160 Gbit/s

TransiNet - Innovative TransportNetworks for the BroadbandInternet (TV)

Teletraffic Engineering for PackedSwitched Services

Multiuser Receiver for CDMASystems

Sequences in CDMA Systems

MULTIMODE: MIMO Techniquesand Antennas

Intelligent Multi-Element Antenna-and Non-Orthogonal Multicarrier-Systems for Modern BroadbandMobile Communication

Optically Controlled Array Antennasfor Wireless Cellular BroadbandNetworks

Mobile Broadband Systems

HHI5/00 – 4/02

EU12/00 – 11/03

BMBF(MultiTeraNet)10/02 – 9/05

DFG6/00 – 6/02

DFG1/01 – 12/02

HHI1/00 – 12/02

BMBF7/00 – 6/03

EU3/02 – 2/04

Industry1/99 – 3/02

EU4/00 – 3/02

BMBF7/01 – 3/02

BMBF1/99 – 6/02

BMBF(UMTS)5/01 – 12/03

Industry1/01 – 3/02

Gerd Großkopf+49(0)30-31002-317grosskopf@hhi.de

Gerd Großkopf+49(0)30-31002-317grosskopf@hhi.de

Gerd Großkopf+49(0)30-31002-317großkopf@hhi.de

Ralf Schäfer+49(0)30-31002-560schaefer@hhi.de

Ralf Schäfer+49(0)30-31002-560schaefer@hhi.de

Peter Kauff+49(0)30-31002-615kauff@hhi.de

Peter Kauff+49(0)30-31002-615kauff@hhi.de

Peter Kauff+49(0)30-31002-615kauff@hhi.de

Guido Heising+49(0)30-31002-226heising@hhi.de

Guido Heising+49(0)30-31002-226heising@hhi.de

Uli Höfker+49(0)30-31002-569hoefker@hhi.de

Maati Talmi+49(0)30-31002-293talmi@hhi.de

Maati Talmi+49(0)30-31002-293talmi@hhi.de

Karsten Grüneberg+49(0)30-31002-262grueneberg@hhi.de

Optical Beamforming Network onSiO2/Si

Optical Beam-formed Antennas forAdaptive Broadband Fixed andMobile Wireless Access Networks

Broadband Optical Access- andInhouse Networking – NetworkArchitecture and Protocols (BM)

Algorithms for a 3D-Realtime VideoConferencing System with highTelepresence

Multi View Synthesis of N ParallelStereo Rigs

Technologies for Hybrid SceneComposition in Interaktive Tele-presence

Immersive Telepresence in theInternet

Advanced Three-dimensionalTelevision System Technologies(TV), ATTEST

Interoperability for VideoCommunication over DistributedNetworks, INVINET

Dynamic Radio for IP Services inVehicular Environment

Digital Cinema/Distribution andProjection Technologies

Key Components for UserConfigurable Terminals, KOKON

Bluetooth- and MPEG-4-based KeyComponents for Mobile Systems

Programmable HYbrid TV Systemwith Integrated CoreS, PHYSICS

44 H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

Electronic Imaging Technology for Multimedia

45H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

Industry9/02 – 3/03

Industry9/02 – 4/03

EU1/00 – 04/02

EU1/00 – 12/02

BMBF(UMTS)4/01 – 12/03

BMBF9/01 – 12/03

EU1/01 – 12/02

BMBF6/01 – 5/04

DFG5/02 – 4/04

DFG8/02 – 7/03

State of Berlin10/02 – 9/03

Industry5/02 – 4/05

Industry10/02 – 12/03

BMBF1/02 – 12/04

Karsten Grüneberg+49(0)30-31002-262grueneberg@hhi.de

Karsten Grüneberg+49(0)30-31002-262grueneberg@hhi.de

Peter Stammnitz+49(0)30-31002-570stammnitz@hhi.de

Oliver Schreer+49(0)30-31002-620schreer@hhi.de

Detlev Marpe+49(0)30-31002-619marpe@hhi.de

Aljoscha Smolic+49(0)30-31002-232smolic@hhi.de

Aljoscha Smolic+49(0)30-31002-232smolic@hhi.de

Thomas Wiegand+49(0)30-31002-617wiegand@hhi.de

Thomas Wiegand+49(0)30-31002-617wiegand@hhi.de

Ralf Schäfer+49(0)30-31002-560schaefer@hhi.de

Ralf Schäfer+49(0)30-31002-560schaefer@hhi.de

Peter Eisert+49(0)30-31002-614eisert@hhi.de

Stefan Rauthenberg+49(0)30-31002-266rauthenberg@hhi.de

René de la Barré+49(0)30-31002-345barre@hhi.de

Development and Implementationof Algorithms and Structures forVideo Projection by LC-Displays

Integrated Hardware Architecturefor Multimedia Broad ImageProject/TriMedia DSP

Systems for Advanced MultimediaBroadcast and IT Services

Virtual Team User Environment

Open Multimedia StreamingArchitecture

Optical Information Systems forTraffic Analysis and Traffic Control/Videobased Traffic Monitoring

Metadata for Advanced ScalableVideo Coding Tools

Image Analysis and Recognition inInformation Systems

Optimization of a Sequency BasedVideo Transmitting

Algorithms for a 3D RealtimeVideoconferencing System withhigh Telepresence

Highly Efficient TV-Transmitting inthe DVB-T Network of Berlin andBrandenburg

Development of an IntelligentVision Platform Including PilotApplications for the Mass Market

Intelligent Scalability forInteroperable Service

3D Techniques for Mixed-RealitySystems

A Communication Platform forInformal and Computer SupportedCommunication in Telework andTelecooperation

Mobile Services for Citizens

Intelligent and User-adaptiveSystems for Navigation andRetrieval of Images

MPEG-7 based Analysis andVisualisation Tools for ArchivingDigital Video

Sensing People – IntelligentCameras and Sensors

Advanced Three-dimensionalTelevision System Technologies,ATTEST

Bringing User Satisfaction to MediaAccess Networks, BUSMAN

Innovative Man-Machine-Interfaces

Lothar Mühlbach+49(0)30-31002-237muehlb@hhi.de

Lothar Mühlbach+49(0)30-31002-237muehlb@hhi.de

Thomas Meiers+49(0)30-31002-218meiers@hhi.de

Thomas Meiers+49(0)30-31002-218meiers@hhi.de

Ivo Keller+49(0)30-31002-387keller@hhi.de

Klaus Hopf+49(0)30-31002-581hopf@hhi.de

Thomas Meiers+49(0)30-31002-218meiers@hhi.de

Jens Faber+49(0)30-31002-235faber@hhi.de

BMWi1/99 – 5/02

BMWA10/02 – 9/04

BMWi1/99 – 3/02

BMWi4/02 – 3/52

BMBF(UMTS)9/01 – 12/03

EU/IST3/02 – 2/04

EU / IST4/02 – 9/04

FhG Munich1/02 – 10/02

46 H H I R E P O R T 2 0 0 2 · R & D A C T I V I T I E S

47H H I R E P O R T 2 0 0 2

Selected Contributions

49H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

A consortium of industry leaders, compris-ing Acterna, Alcatel SEL, Infineon Technolo-gies, Lucent Technologies, Siemens, T-Sys-tems Nova and VPI Systems, has collaborat-ed with 20 research institutes, universitiesand SMEs to develop and field-trial opticalnetworking technologies, network elements,components, protocols, and access networktechnologies [1]. Using an in-place standardsingle mode fibre infrastructure provided byT-Systems Nova, a complete demonstrationcommunication network, including long dis-tance network, metropolitan network, andseveral access systems, has been implement-ed (see figure).

Basic functions of next-generation trans-port systems at 160 Gb/s and WDM systemswith very high capacities (up to 32 x 40 Gb/s)have been field-trialled on this platform. Dy-namic adding/dropping of WDM channels,automatic switching and all-optical intercon-necting of different vendor’s systems have al-so been demonstrated. Other functions havealso been trialled, including the transport ofvarious client signals, novel routing func-tions, performance monitoring of WDMchannels, and basic functions for networkmanagement in a multi-vendor environment.In the area of network access, hybrid fibrecoax and fibre radio techniques and their keycomponents were also developed and test-ed. In addition to the numerous field trialsconducted individually by the project part-ners, 15 cross-project field trials were alsoconducted.

The work of KomNet was completed in2002. Even though the systems and compo-nents were not designed for maximum de-mand, but for robustness and reliable opera-

tion under realistic conditions, several out-standing results were achieved, which de-monstrate impressively the capability of do-mestic R&D in this field. The results providea solid base for solving current tasks of prod-uct-oriented development and for further re-search on photonic communication networks.

As described in more detail in the follow-ing contributions, HHI was involved with sev-eral projects on the design and simulation ofoptical networks, the evaluation of networkelements, ultra high-speed time division mul-tiplexing transmission up to 160 Gb/s, 40 Gb/sphotodetectors and receivers, all-polymeroptical add-drop multiplexers, optical signalregenerators, transceiver photonic ICs, andpicosecond opto-electronic ICs.

In addition, the KomNet Systems Integra-tion Office at HHI managed the implementa-tion of the demonstration network and thefield trials. This work was supported by theindustrial partners and was partly funded bythe German Federal Ministry of Educationand Research under grant 01 BP 805.

[1] K.-D. Langer and J. Vathke, “Overviewand recent developments of the GermanR&D initiative KomNet”, Proc. Int. Conf.Transparent Optical Networks (ICTON),Th.B.3, Warsaw (PL), April 2002.

Klaus-Dieter Langer (langer@hhi.de)

Research Initiative KomNet – Review and Final Results

Over the past four years, under the framework of the German R&D initiative KomNet, anindustry-based consortium has developed enabling technologies for future multi-vendormulti-client wavelength division multiplexing (WDM) communication networks. Many ex-cellent results were achieved. HHI contributed several R&D projects and the SystemsIntegration Office to KomNet.

German KomNet testbedtopology. The entirenetwork was demon-strated by Acterna,Alcatel SEL, LucentTechnologies, InfineonTechnologies, Siemensand T-Systems Nova.

50

Two important developments in opticalcommunications networks can be observed:• In recent years the bandwidth available on

optical fibres has increased by orders of magnitude, mainly due to wavelength-division multiplexing (WDM) technology.

• The exponential growth of traffic generat-ed by the Internet is causing a paradigm shift in optical networking away from circuit switching and towards packet switching.

The objective of the joint research projectTransiNet (started in June 2000) is to devel-op new networking technologies to carry IPtraffic over WDM optical networks in an effi-cient manner.

The Partners in the TransiNet project are:• Fraunhofer-Institut für Nachrichtentechnik

– Heinrich-Hertz-Institut, Berlin (FhG-HHI)• University of Stuttgart, Institute of

Communication Networks and Computer Engineering (IKR)

• T-Systems Nova GmbH,Technologiezentrum(T-Systems Nova)

• Technical University of Berlin, Faculty of Electrical Engineering and Computer Science, Telecommunication Networks Group (TKN)

• University of Technology Munich, Institute of Communication Networks (LKN)

Cooperation among the partners is orga-nized in working groups. The focal points inTransiNet are Network Operation, Architec-tures, Routing and Resilience, and Wireless.

The main research areas in TransiNet forthe next-generation optical Internet are newconcepts for network and node architecturesand their corresponding protocols, standardsand technologies, traffic aggregation, scala-bility of WDM networks, quality of services(QoS), network management, resilience, andthe interworking and integration of high-speed photonic and mobile communicationsystems.

As there are still many technological prob-lems in optical packet switching, optical wave-length switching and, probably later, opticallabel switching (OLS) or optical burst switch-ing (OBS), are considered to be the next stepstowards more dynamic optical networks.

Advanced optical subsystems for opticallyswitched dynamic networks are being inves-tigated in the HHI Department of OpticalNetworks (ON), including WDM transmis-sion, add-drop multiplexers, optical cross-connects and wavelength router/switches.Their interworking with higher-layer proto-cols, mainly IP, is also being studied.

Parts of an IP-optimized air interface arebeing developed in the HHI Department ofBroadband Mobile Communication Networks(BM). The main research areas are new signalprocessing algorithms, estimation of the ra-dio channel, resource allocation, and teletraf-fic techniques for the planning process.

This work is supported by the FederalMinistry of Education and Research undergrant 01 AK 020A.

For more information visit www.transinet.de

Jürgen Saniter (saniter@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

TransiNet – Innovative Transport Networks for the Broadband Internet

The research project TransiNet aims to develop new concepts for carrying IP traffic overwavelength division multiplexed (WDM) and wireless networks. This contribution gives ashort overview of the TransiNet project.

Burst-switched opticalnetwork

51H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Distributed Raman amplification (DRA) hasbecome very attractive in high-speed broad-band WDM transmission systems, especiallyfor long-haul transmission and low noise pre-amplification.

We investigated the dynamics of distrib-uted Raman amplified WDM links and com-pared them with similar Erbium doped fibreamplifier (EDFA) links to evaluate the signalpower responses of the channels when all orparts of the channels are switched and gaincontrol is not used. Two 8 x 10 Gb/s WDMlinks were used, each with five stage ampli-fiers (distributed Raman amplifiers or EDFAswith 73 dB gain) and dispersion-managed200 km fibres (Fig. 1).

Raman amplification was implemented bypumping the five fibres with Raman fibrelasers (1455 nm, 2.5 W) and laser diodes(1447 nm, 0.24 W). Channel switching andgeneration of data bursts (300 µs long with10 to 1000 µs interruption times) were per-formed using an acousto-optical switch.

The experiments show that cascadedEDFAs generate much higher signal powerpeaks in switched channels (up to 50 timeslarger) than Raman amplifiers for long signalinterruptions (Fig. 2) [1].

If the pauses are less than 60 µs, the peakswith EDFAs differ by a factor of only twofrom those with Raman amplifiers (Fig. 3).

For long-haul 8 x 10 Gb/s transmissionover 2600 km with 65 cascaded distributedRaman amplifiers and 4 out of 8 switchedchannels, the signal peaks are only 2.4 timeslarger than the steady state signal powers.From these results and the low noise andbroadband amplification properties, it can beconcluded that distributed Raman amplifiersbehave significantly better than EDFAs forboth non-switched and switched channelsand signals. This, plus the decreasing pricesof the Raman pump lasers, will lead to fur-ther use of Raman amplification.

When Raman amplification is applied inthe field, appropriate safety measures can beinstalled. [1] E. Schulze et al., “All-Raman amplified

links in comparison to EDFA links in case ofswitched traffic”, ECOC 2002, Symposium 3.8.

Elmar Schulze (schulze@hhi.de)

All-Raman Amplified Links and EDFA Links with Switched Channels

Transmission links with cascaded distributed Raman amplifiers are compared with thoseusing EDFAs for switched 8x10 Gb/s WDM channels. The switching-induced signal powerpeaks are up to 50 times lower with distributed Raman amplification than with EDFAs ifgain control is not used.

Fig. 1a: Switched distributedRaman link

Fig. 1b:

Switched EDFA link

Fig. 2: Signal power peaks

generated by cascaded

distributed Raman am-plifiers and EDFAs withswitched traffic

Fig. 3:

Normalised signal powerpeaks as functions of the

signal interruption time(normalised signal pow-

er peak is the ratio signalpower peaks/steady

state signal power)

52

Optical performance monitoring is a key is-sue for the management of future transpar-ent WDM networks. In a flexible transport in-frastructure, the quality and switching stateof a light path should be definable indepen-dent of the client signal. With the controlmodulation technique, a low bitrate digitalcontrol signal is physically linked to eachWDM client signal by modulating the opticalcarrier (Fig. 1). The insertion of the controlsignal at the edge of the transparent networkbecomes client-independent by using addi-tional optical modulation. The control signalis extracted for monitoring purposes at a net-work node along the light path of the clientsignal by power tapping and filtering (Fig. 2).

The main advantages of the control modu-lation technique over other performancemonitoring techniques are its high flexibilityand accuracy and moderate costs (only nar-row-band processing is employed for thecontrol modulation).

The control signal is made highly suscepti-ble to impairments that affect the high-speed client signals by using a high-frequen-cy electrical subcarrier. Typical examples ofimpairments affecting the control signal areresidual chromatic dispersion of a fibre linkand distortion due to fibre nonlinearity, e.g.self phase modulation. Another importanttransmission impairment is the noise that isadded by optical amplifiers. Figures 3 and 4show one-channel simulation results for anoptically amplified, dispersion-compensatedlink of 800 km length. The quality (receiversensitivity) of a 10 Gb/s client with a 50 Mb/scontrol signal is displayed as a functions ofeither the compensation ratio or the fibrelaunch power.

The proper choice of the control modula-tion parameters (subcarrier frequency9.75 GHz and modulation index 20 %) re-sults in the desired early warning function forthe client signal impairment due to fibre dis-persion, amplifier noise and fibre nonlineari-ties.

The simulation results were confirmed bycorresponding loop experiments.

[1] M. Rohde et al., “Transparent perfor-mance monitoring and channel identificationby new client independent control modula-tion technique”, Electr. Lett., vol. 38, no. 12,June 2002, pp. 587-88.

Michael Rohde (mrohde@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Monitoring of Transmission Impairments in Transparent WDM Networksusing a Novel Control Modulation Technique

A new client-independent control-modulation monitoring technique for transparent net-works is applied to monitor client signal impairments due to noise, fibre nonlinearitiesand chromatic dispersion. The early warning function of the control signal for client sig-nal degradation is demonstrated by experiments and simulations.

Fig. 1: Client-independent

insertion of the controlsignal at the edge of the

network

Fig. 2:

Extraction of the control

signal at a network node

Fig. 3:

Monitoring of residualchromatic dispersion

Fig. 4: Monitoring of amplified

spontaneous emission

noise (ASE) and selfphase modulation (SPM)

53H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

With the introduction of transparent net-working, optical communication signals thatpass through network links of different fibretypes may show unpredictable transmissionperformance. For various homogeneous andinhomogeneous fibre infrastructures the over-all performance of 10 Gb/s NRZ WDM trans-mission is investigated. Typical parameters ofthe fibres under investigation are given inFig. 1.

For each fibre link type, an optimised de-sign (with regard to dispersion map and fibreinput powers) was developed using exten-sive numerical simulations. It was found thatthe performance of hybrid and hybrid in-verse schemes, which are both symmetricalin terms of the dispersion map (Fig. 2), is su-perior to that of pure post-compensation orpre-compensation schemes [1].

To verify the simulation results, recirculat-ing loop experiments were carried out. Theloop consisted of fibre links as in Fig. 2, andup to 16 channels at 100 GHz spacings were

transmitted. The maximum reach for the ho-mogeneous G.652 and LEAF links is morethan 4000 km for single channels, but only2500 km for WDM transmission over theLEAF fibre (Fig. 3). As expected, the nonlin-ear channel distortion [2] is higher for theLEAF link than for G.652 link due to the re-duced dispersion of LEAF.

An inhomogeneous link of alternately cas-caded sections was then constructed, usingthe optimal parameter values for the individ-ual fibres. With this link up to 2500 km with-out FEC and Raman amplification wasachieved for WDM channels.

These results suggest that inhomogeneousfibre sections, when individually optimised,can be cascaded trouble-free in arbitrary se-quence.

[1] D. Breuer et al., Asia Pacific Opt. Com.Conf. 2001, Vol. 4584, 104-114.

[2] C. Caspar et al., OFC 2001, paper WI5.

Christoph Caspar (caspar@hhi.de)

WDM Transmission over Mixed Fibre Infrastructures

The existing global fibre infrastructure uses various fibre types, including standard single-mode fibre (G.652) and non-zero dispersion-shifted fibre (NZDSF). It is shown, by way ofan example using G.652 and Corning® LEAF® fibre, that transmission over inhomoge-neous network links can take place without additional penalties if the transmission perfor-mance of the individual fibre sections is optimised.

Fig. 1:

Fibre parameters

Fig. 2: Compensation schemeswith corresponding

dispersion maps

Fig. 3: System penalty for

10 Gb/s NRZ ASK singlechannel and WDM ex-

periments

54

During recent years telecommunicationcarriers have widely deployed NZDSFs forWDM long haul transmission at and beyond10 Gb/s, where dispersion compensation isneeded even for these new fibre types. Dueto the reduced chromatic dispersion ofNZDSFs, compared to that of standard singlemode fibre (ITU-T G.652), less dispersioncompensation is needed and thus there arereduced network costs. However, with themove towards ultra-long haul 10 Gb/s sys-tems and the desire to future-proof networksfor 40 Gb/s, a new generation of DCFs withdispersion slope compensation has evolved.The most widely available DCFs are opti-mized for G.652, particularly those designedfor dispersion slope compensation. These de-vices, when used with NZDSFs, lead to slopemismatches that limit transmission perfor-mance and reduce the usable wavelengthband [1].

Transmission experiments with 10 Gb/sNRZ ASK signals were carried out using aWDM loop testbed (Fig. 1) containingCorning® LEAF® fibre in combination with anovel dispersion slope compensating fibreDCFLEAF optimized for LEAF. These results arecompared with those obtained with LEAFand a conventional DCF matched to G.652(DCFG.652). Chromatic dispersion-optimizedsections in which the accumulated dispersionhad a symmetrical characteristic were used inthe loop [2-3]. The critical link parametersare the fibre input powers into the LEAF and

DCF fibres and the chromatic dispersioncompensation ratioCR = |DDCF*LDCF|/(DLEAF*LLEAF). The experi-ments showed that, for a reach of 1500 km,a CR range from 87 % to 99 % is tolerable.In Fig. 2 it is seen that in this range the us-able wavelength band of 7.5 nm with theconventional DCFG.652 is increased to 50 nmwhen the new DCFLEAF is used.

This means that LEAF fibre in combinationwith the new DCFLEAF is now suitable forlong-haul WDM transmission over more thanthe entire C Band.

[1] M. Wandel et al., “Dispersion compen-sating fibers for non-zero dispersion fibers”,Optical Fiber Communication Conference,2002, WU1.

[2] D. Breuer et al., “Symmetrical disper-sion compensation for standard monomodefiber based communication systems withlarge amplifier spacing,” Optics Letters, 13(1997), pp. 982-984.

[3] N. Hanik et al., “Optimised design oftransparent optical domains”, Proc. EuropeanConference on Optical Communications, 3(2000), pp. 992-994.

Christoph Caspar (caspar@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Novel Slope-Compensating Optical Fibres Permits Capacity Increase forFuture-Proof Long Haul WDM Systems

The upgrade of the existing non-zero dispersion-shifted fibre (NZDSF) infrastructure forfuture-proof broadband long haul transmission is experimentally demonstrated using anovel slope-compensating dispersion compensating fibre (DCF). For 1500 km reach theaccessible bandwidth is expanded to 50 nm instead of the 7.5 nm window achieved usinga conventional DCF designed for standard single-mode fibre.

Fig. 1:

Recirculating WDM loop

testbed

Fig. 2:

Broadband slope com-

pensation with the new

DCFLEAF

55H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

The optical bursts in an OBS network havetypical lengths ranging from a few microsec-onds to several hundred microseconds, sothat switching times should be less than onemicrosecond. Switches using semiconductoroptical amplifiers (SOAs), with switchingtimes in the nanosecond range, are well suit-ed for this application.

To reduce signal degradation and cost weconsidered only single-stage node architec-tures. A power budget analysis shows thatthe “Tune-and-Select” (TAS) architecture(Fig. 1) has the potential to build largenodes. This node has N input/output fibresand M wavelengths per fibre. The incomingburst is converted into the desired outputwavelength by a tunable wavelength con-verter and then switched to the desired out-put fibre by SOA gates.

To estimate the size and the cascadabilityof the TAS nodes for a 10 Gbit/s line rate, thebit error rate respectively Q-factor was calcu-lated [1]. The noise generated by the opticalamplifiers (SOA, EDFA) is considered and aworst case calculation is performed for cross-talk analysis. Figure 2 shows the Q-factor as afunction of the number of fibres (N) for vari-ous numbers of wavelengths per fibre (M) fora single node. To leave enough margin forother impairments, a Q of 10 (BER = 10-22) istaken as the limit of signal degradation. It isseen that a TAS node with 512 ports (N = 16and M = 32) can be built.

The cascadability of the nodes depends onthe kind of wavelength converters. If 3R re-generating wavelength converters are used,the accumulation of signal degradation ceas-es at each converter, and many TAS nodescan be cascaded. However, the degradationsaccumulate if a linear converter is used, andthe maximum size of TAS nodes is consider-ably reduced. For example, for four cascadednodes with 32 wavelengths per fibre, we canonly implement a TAS node with 4 input andoutput fibres if linear converters are used.

This work is supported by the FederalMinistry of Education and Research undergrant 01 AK 020A.

[1] H. Feng, E. Patzak and J. Saniter, “Sizeand cascadability limits of SOA based burstswitching nodes”, Proc. ECOC ‘02,Copenhagen (DK), Sept. 2002, vol. 3, 8.5.5.

Hao Buchta (buchta@hhi.de)

Size and Cascadability Limits of SOA-based Burst Switching Nodes

Optical Burst Switching (OBS) is a promising candidate for a more dynamic optical layerto support the next generation Internet. OBS will only be possible if fast and large switch-ing nodes can be built. The size and cascadability of such nodes are limited by signaldegradation caused by power losses, noise, and crosstalk. Our analysis shows that nodeswith 16 fibres and 32 wavelengths per fibre are possible.

Fig. 2: Q-factor versus numberof fibres N for variousnumbers of wavelengthsper fibre M

Fig. 1: Tune-and-select (TAS)

OBS switching node

56

An all-optical 3R signal regenerator (Re-amplification, Re-timing, Re-shaping) needsclock recovery circuitry, a decision element,and circuitry for combining the clock recov-ery and decision functions. In the standardarchitecture the optical clock pulses are ap-plied to a nonlinear decision gate that is con-trolled by the data signal. The data informa-tion is thus encoded onto the clock pulses.The timing and shape of the (stable) clockpulses determine the output quality. How-ever, the clock also determines the outputwavelength, and thus a matched opticalclock must be fabricated for each wave-length in the ITU grid.

In our novel regenerator architecture [1]data pulses are delayed by half a bit relativeto the clock pulses and combined (balancedin power) with the Alternating Data Clock(ADC) signal (Fig. 1). The ADC signal is con-stant during a sequence of “1” bits and itdrops down during a “0” bit. The timing andshape of the resulting modulation in theADC signal are determined by the (stable)clock pulses, not by the (possibly degraded)data signal. The ADC signal controls a wave-length-converting decision element in whichthe modulation signal is encoded onto a CWsignal. A tunable laser or a commerciallyavailable laser in the ITU grid can be used todefine the output wavelength in a flexiblemanner, while waveform shape and timingare determined by the clock – as needed forregeneration.

A 3R regenerator based on the ADCscheme was assembled (Fig. 2) and tested at40 Gb/s [2]. Optical clock recovery was per-formed by the self-pulsating PhaseCOMB laserdeveloped at HHI [3]. A semiconductor opti-cal amplifier (SOA) followed by a delayed in-

terferometer (DI) was used as the wave-length-converting decision element. A de-graded 40 Gb/s PRBS signal (eye diagram atthe left in Fig. 2) was injected into this re-generator. The output eye diagram is shownin Fig. 2, right. The improved quality of theoutput signal (both jitter and shape) canclearly be seen.

The regenerator presented here is the first40 Gb/s true all-optical 3R regenerator usingcompact semiconductor devices for clock re-covery as well as for decision.

[1] B. Sartorius et al., “Novel 3R regenera-tor architecture with wavelength flexible out-put”, ECOC 2002, paper 6.3.3.,Copenhagen (DK).

[2] C. Bornholdt et al., “Novel 3R regener-ator concept demonstrated at 40 Gb/s”,ECOC 2002, post-deadline paper PD 4.8,Copenhagen (DK).

[3] C. Bornholdt et al., “Self-pulsating DFB-laser for all-optical clock recovery”, Electron.Lett., vol. 36, no. 4, 2000, pp. 327-328.

Bernd Sartorius (sartorius@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Novel All-Optical 3R Regenerator with Flexible Choice of OutputWavelength

All-optical 3R signal regeneration and wavelength conversion are key functions needed inall-optical switching nodes. We developed a novel 3R architecture combining regenera-tion and flexible wavelength conversion. All-optical 3R regeneration at 40 Gb/s is demon-strated using compact semiconductor devices.

Fig. 1: Schematic of the

Alternating Data Clock(ADC) 3R regenerator.

Data are delayed by halfa bit relative to the clock,

and the combined ADCsignal is converted to an

arbitrary wavelength.

Fig. 2: Assembled 3R regenera-

tor applying compact

semiconductor devices

for clock recovery anddecision. Eye diagrams

show degraded 40 Gb/s

input signal (left) and

regenerated signal at acontrollable wavelength

(right).

57H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Phase Controlled Mode Beating(PhaseCOMB) is a new operation principlefor high-speed all-optical clocks. It is basedon the use of three-section lasers comprisingtwo DFB sections, detuned by about the stopbandwidth, and an integrated phase tuningsection (Fig. 1). The two adjacent inner DFBmodes (+1, -2) are selected for lasing by thephase tuning section. Beating of the twocoupled modes leads to the wanted self-pul-sation (SP) at a frequency determined by thespectral separation of the lasing modes. 3Rregeneration at up to 80 GHz has been re-alised at HHI using PhaseCOMB lasers.

Modelling of such devices was done in co-operation with partners at Humboldt Univer-sity and the Weierstrass Institute using theirsimulation tool LDSL [1]. When the resultsare compared with the measurements, twoeffects not considered in [1] were now foundto play an important role: spatial hole burn-ing (SHB) and residual interface reflections(RIRs).

SHB is a nonuniform carrier density due tononuniform stimulated recombination. It isaccompanied by a shift of the Bragg reso-nance by nearly 1 nm (Fig. 2) that perturbsthe selection of the wanted modes and re-duces the sizes of the parameter regions withuseful self-pulsations. Nevertheless, high qual-ity SPs from 20 GHz up to several hundredGHz can be generated by properly choosingthe grating detuning as well as the DFB andphase section lengths (Fig. 3).

The impact of RIR on the self-pulsations isillustrated in Fig. 4. Depending on the phas-es of the RIRs relative to the those of the DFBgratings, the frequency varies over a wide

range, and the SP may even disappear(white area). Since this phase is a randomparameter, not controllable by technology, alarge scatter from device to device is theconsequence. By calculations we have shownthat the interface reflectivity R must be lessthan 0.1 % to get a uniformly good perfor-mance of the devices.

[1] M. Möhrle et al., “Detuned gratingmulti-section-RW-DFB-lasers for high speedoptical signal processing”, IEEE SelectedTopics on Quantum Electronics, 7, 217 (2001).

Hans-Jürgen Wünsche (wuensche@hhi.de)

Modelling of PhaseCOMB Laser for Optical Clock Recovery

The simulation tool LDSL was applied to investigate the performance of a new operationprinciple for high-speed all-optical clock lasers when there are perturbations due to longi-tudinal spatial hole burning and residual reflections at the interfaces. Conclusions aredrawn about how to suppress these perturbations.

Fig. 2: Spatial hole burning inthe carrier densities andrelated shift of theBragg resonance

Fig. 1:

Sketch of the

PhaseCOMB clock and

its principle of operation

Fig. 4: Influence of the phases

of interface reflectivity

R = 1 %. White: no SP.Grey scale: SP from 29 GHz (dark) to 44 GHz

(pale-grey).

Fig. 3: Variation of the SP

frequency with the d

etuning of the Bragg

gratings. The vertical

spread of the islands is

due to phase tuning.

The lines show the sepa-

rations between all com-

binations of DFB modes.

58

Optical demultiplexing is a key function inhigh speed systems that are optical time-divi-sion multiplexed (OTDM), since it enablestransmission at bit rates beyond the speed ofelectronic signal processing. Moreover a costreduction can be obtained by avoiding opto-electronic conversion at high data rates. Thedevices needed in the DEMUX are an opticalgate and a clock recovery unit. The clock re-covery device operates at the base rate of theOTDM systems and triggers the gate to se-lect particular channels for detection. How-ever, the switching window must have a tim-ing precision matched to the line rate. Sincethe relative spacing between the adjacentOTDM channels decreases with increasingchannel number, the timing stability mustmatch the demands of the line rate.

Presently 160 Gb/s OTDM systems with40 Gb/s base rates are under investigation.We therefore evaluate the application of anovel 40 GHz self-pulsating laser for all-opti-cal clock recovery [1] in a 160 to 40 Gb/sDEMUX experiment.

The experimental setup is shown in Figure 1.This can be regarded as general 160 Gb/stestbed for the all-optical clock recovery

module. A 160 Gb/s OTDM signal, based on4 x 40 Gb/s electrical time-division multi-plexed (ETDM) channels, is launched intothe DEMUX using an electrically driven elec-tro-absorption modulator (EAM) acting as anoptical gate [2]. The demultiplexed 40 Gb/ssignal at the output of the EAM is amplifiedand divided into two streams. One stream isused for signal detection in a 40 Gb/s ETDMreceiver, and the other is injected into theself-pulsating laser. The 40 GHz optical clockpulses from the device are converted to anelectrical signal which drives the EAM.

The ETDM receiver was used to character-ize the DEMUX performance by BER mea-surements on the demultiplexed 40, 80 and160 Gb/s signals. The results are summarizedin Fig. 2. The BER curves demonstrate error-free demultiplexing down to a BER of lessthen 10-9. The system penalties are only0.7 dB for 80 Gb/s and 2.7 dB for 160 Gb/s,allowing for the 3 dB drop in sensitivitywhen the bit rate is doubled.

In conclusion, 160 : 40 Gb/s optical demul-tiplexing with an all-optical clock recoverydevice was demonstrated. The timing stabili-ty of the synchronized 40 GHz self-pulsatinglaser has a jitter matched to the operationaldemands at 160 Gb/s. This DEMUX could beupgraded to an all-optical solution in futureif an optically driven gate, such as an inter-ferometer-based structure, were to be used.

[1] S. Bauer et al., Electron. Lett., vol. 38,pp. 334-335, 2002.

[2] E. Lach et al., Proc. OFC 2002, TuA2,2002, Anaheim, USA.

Olaf Brox (brox@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

160 to 40 Gb/s Demultiplexing Using a Self-Pulsating Laser-Based ClockRecovery Device

Optical demultiplexing from 160 to 40 Gb/s is performed using a self-pulsating laser-based clock recovery device. Error-free operation is obtained, thereby demonstrating theexcellent timing stability of the optical clock.

Fig. 2:

System performance of

the DEMUX receiver fordemultiplexing 40,

80 and 160 Gb/s signals

to a 40 Gb/s signal

Fig. 1: Experimental setup of

the 160 to 40 Gb/s DEMUX experiment

59H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

A key functionality for future all-opticalnetworks will be optical pulse sources, whichare required for several applications in signalprocessing. Particularly interesting are appli-cations where the pulses are synchronised byoptical data injection. This clock functionalitycan be used for example for the control ofadd-drop multiplexers in OTDM systems.The generation of pulses using integratedoptics offers many advantages. Besides over-coming the speed limitations of their elec-tronic counterparts, there are the benefits oflow power consumption, low cost and highreliability.

There are now several competing methodsfor high speed pulse generation, includingmode-locked lasers (MLLs) and PhaseCOMBlasers using two coupled DFB lasers giving abeating pulsation. Both designs suffer fromthe complex technology needed. In the caseof the MLL the pulsation frequency is definedby the internal roundtrip time, so that thedevice length must be controlled very pre-cisely, whereas the PhaseCOMB laser relieson the detuning of DFB gratings, which re-quires additional technological steps.

The new approach presented here is a de-layed feedback setup using a single-modelaser. It can be used for the generation ofpulsations in which the frequency scales withthe feedback level. The innovation in the AFLis the integration of an active feedback cavity(AFC) in a DFB laser, comprising both phaseand amplifier sections. This overcomes theinherent losses of passive solutions. The largeamount of feedback due to the internal am-plifier results in pulse frequencies up to thelimit given by the roundtrip time in the AFC.Details are given in [1].

A device realised for 40 GHz self-pulsationis shown in Fig. 1. It is designed as an index-coupled bulk hetero-structure ridge-wave-guide laser comprising a 200 µm DFB sec-tion, a 350 µm passive phase tuning sectionand a 250 µm active section. The DFB facetis anti-reflection coated and an uncoatedend facet acts as a mirror.

The device delivers an output power of1 mW into the fibre and has a large frequen-cy tuning range of 20 GHz, which can becontrolled by simply adjusting the amplifier

and phase currents. The performance of thedevice remains constant over the whole tun-ing range. Typical data are an extinction ra-tio of 10 dB and a phase noise equivalent jit-ter of 300 fs when locked to an injected datasignal. Figure 2 shows pulse traces for a40 Gb/s data signal and the recovered clocksignal.

In summary the active feedback laser is acost-effective pulse source that meets the de-mands of future optical networks.

The results have been obtained under theframework of the Research Partner Programof Alcatel.

[1] S. Bauer, O. Brox, J. Kreissl, G. Sahinand B. Sartorius, “Optical microwavesource”, Electron. Lett., vol. 38, pp. 334-335,2002.

Stefan Bauer (bauer@hhi.de)

Active Feedback Laser for Clock Recovery

We present the active feedback laser (AFL) as a new device concept for tunable high fre-quency pulse generation. The simple design allows for cost-effective fabrication. Its per-formance is demonstrated to be comparable to that of other solutions for all-optical clockrecovery.

Fig. 1: Schematic of active feedback laser for 40 GHz self pulsation

Fig. 2:

Pulse traces of the

recovered clock and the

injected data signal at

40 Gb/s

60

In future high-speed TDM systems (160 Gb/sand above), optical sampling for in-servicequality monitoring at the full line rate will bevital. We demonstrate a semiconductor-basedsampling system that allows the measure-ment of 320 Gb/s eye diagrams [1]. Thesampling gate is a GT-UNI, which uses thegain-transparent (GT) principle in which theoptical control pulses are in the spectral gainregion of an SOA and cause a change of therefractive index at a signal wavelength in thetransparency region (i.e. below the band-gap) of the SOA. This leads to excellent in-put-to-output linearity and wide wavelengthtunability of the input signal, which are bothadvantageous for optical sampling.

Figure 1 shows schematically the experi-mental setup. A 320 Gb/s data signal wasgenerated by multiplexing the signal of a10 Gb/s PRBS RZ transmitter (1550 nm,650 fs sech2 pulses, 0.2 ps rms timing jitter).Part of the 10 Gb/s signal was used for RFclock line extraction. The sampling systemcomprised three main parts: the samplingpulse source, the GT-UNI sampling gate andthe opto-electrical (O/E) detector. For thesampling pulse source we used a semicon-ductor modelocked laser (TMLL) at 1300 nm(1.5 ps sech2 pulses, 0.2 ps rms timing jitter),driven by the 10 GHz extracted clock signalshifted by ∆f = 50 kHz. Due to the limitedclock speed of the digital oscilloscope in theO/E detector, the sampling pulse rate was re-duced to 310 MHz by a LiNbO3 Mach-Zehnder modulator. The sampling pulsesopened a short gating window in the GT-UNI and the incoming data signal was gatedto the output port (the optical sample). Thegating window width of 1.8 ps was deter-mined by a piece of polarization-maintainingfibre (PMF) in the GT-UNI, with a length of1.2 m. Finally, the peak powers of the opticalsamples were detected using a photodiode(1 GHz bandwidth) and displayed on a digi-tal oscilloscope, which was triggered by thefrequency offset ∆f.

Figure 2 shows the measured optical eyediagram of a 320 Gb/s data signal. The aver-age powers of the data signal and samplingpulses at the input of the GT-UNI samplinggate were +23 dBm and -4 dBm, respective-ly.

The eyes have a clear opening and thesame shapes at a persistence of 120 traces.From the eye diagrams, we obtain a FWHMof the eyes of about 2.0 ps, which corre-sponds to an optical bandwidth of the sam-pling system of about 250 GHz. This is ingood agreement with the gating windowwidth of the GT-UNI, which we measuredearlier. Jitter of about 650 fs can be estimat-ed from a horizontal histogram of the flanksof the eyes.

[1] C. Schmidt, C. Schubert, S. Watanabe,F. Futami, R. Ludwig and H. G. Weber,“320 Gb/s all-optical eye diagram samplingusing gain-transparent ultrafast-nonlinear in-terferometer (GT-UNI)”, Proc. ECOC ‘02,Copenhagen (DK), Sep. 2002, paper 2.1.3.

Carsten Schmidt(carsten.schmidt@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

320 Gb/s Optical Sampling

A semiconductor-based all-optical sampling system to display a 320 Gb/s optical eye dia-gram is demonstrated for the first time. The system uses a gain-transparent ultrafast non-linear interferometer (GT-UNI) as the sampling gate.

Fig. 1: Experimental setup

Fig. 2:

Optical eye diagram of a

320 Gb/s data signal

(4 channels turned on)

61H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Clock recovery is an essential operation indevices such as receivers, regenerators, add-drop multiplexers and in-field optical sam-pling systems. We report on innovations for160 Gb/s clock recovery using the electro-optical PLL described in [1]. The innovationsare the use of an EAM as a phase comparatorand a differential scheme in which the EAMis operated with two counter-propagatingdata signals. The locking stability is improvedby this differential scheme.

The clock recovery setup is shown in Fig. 1.The 160 Gb/s optical data signal (single po-larization) is split into two branches andpassed through the EAM using two circula-tors. After electro-optical conversion the twosignals are recombined to drive the 10 GHzvoltage-controlled oscillator (VCO). The VCOsignal is finally multiplied to 40 GHz and fedinto the electrical input of the EAM to closethe loop of the PLL.

In this setup the EAM acts as an ultra-fastelectro-optical phase comparator. The opti-cal powers transmitted through the EAM toboth sides are determined by the relativephase between the data signal and the40 GHz RF signal driving the EAM. Figure 2(upper traces) shows these two signals as afunction of the relative phase. The two sig-nals are phase-shifted because of the opticaldelay in one branch at the EAM input. Thedifference between these two electrical sig-

nals results in a bipolar feedback signal(Fig 2, lower trace) for the VCO, which is,within the locking-range, proportional to therelative phase.

The results of a 160 Gb/s to 10 Gb/s de-multiplexing experiment are shown in Fig. 3.The bit-error rates (BERs) shown as open cir-cles were measured with the electrical trans-mitter clock driving the demultiplexer, whilethe grey triangles are the measurements us-ing the recovered clock. It can be seen thatthe BER performance of the demultiplexerwas the same in both cases. Hence no penal-ty is incurred due to the clock recovery oper-ation.

The design of this clock recovery device isindependent of the polarization. Furthermoreit has the potential for hybrid planar lightwave circuit integration if the circulators arereplaced by 3 dB couplers.

[1] T. Yamamoto, L. K. Oxenløwe, C.Schmidt, C. Schubert, E. Hilliger, U. Feiste, J.Berger, R. Ludwig and H. G. Weber, “Clockrecovery from 160 Gbit/s data signals usingphase-locked loop with interferometric opti-cal switch based on semiconductor opticalamplifier”, Electron. Lett., vol. 37, no. 8,2001, pp. 509-510.

Christof Börner (boerner@hhi.de)

160 Gb/s Optical Clock Recovery using an Electro-Absorption Modulator

A 10 GHz clock recovery device for a 160 Gb/s RZ data signal is demonstrated using a bi-directionally operated electro-absorption modulator (EAM) as phase comparator. It em-ploys a differential detection scheme and achieves excellent locking stability.

Fig. 2:

Transmitted outputpowers of the EAM inboth directions (upper

traces) at 40 Gb/s.

Subtraction yields abipolar VCO feedbacksignal (lower trace).

Fig. 1:

Schematic of the clock

recovery setup

Fig. 3: Bit-error rates for demul-tiplexing from 160 Gb/sto 10 Gb/s using theclock of the 10 Gb/stransmitter (open circles)and the recovered clock

(grey triangles)

62

Semiconductor-based electro-absorptionmodulators (EAMs) are very attractive as ver-satile optical components in high-speed opti-cal communication systems. They can be usedfor operations such as pulse generation, clockrecovery and demultiplexing. Their advan-tages are compactness, polarization insensi-tivity and integrability with other compo-nents. The disadvantage of EAMs is their lim-ited operation speed, which depends on theelectrical bandwidth. Usually two cascadedEAMs are used to overcome the bandwidthlimitation and to reduce the switching time.

The Self-Cascaded Electro-Absorption Mod-ulator (SCEAM) significantly improves theswitching performance of a commerciallyavailable EAM by using it in a bidirectionalmode. In a SCEAM the light signal passesthrough the same EAM twice, once in eachdirection. As a result the switching window isshortened and the extinction ratio is in-creased.

The SCEAM consists of an optical three-port circulator, an EAM and an optical feed-back loop (Fig. 1). The input light passes viathe circulator through the EAM, where it isswitched for the first time. In the circulatorfeedback loop the signal is amplified and fil-tered before it passes through the EAM inthe opposite direction, where it is switchedfor the second time. The optical delay line isused to synchronize the second pass to thefirst pass.

Double switching of the same signal resultsin a larger extinction ratio and a shorterswitching window. Appropriate detuning ofthe loop delay shortens the width of theswitching window even further, but at theexpense of a reduction of the extinction ratioand an increased insertion loss. Since theSCEAM is insensitive to polarization and theadjustment of the delay is not critical, the

setup is robust to changes of the environ-ment and operation conditions. All compo-nents necessary to set up a SCEAM are stan-dard optical components.

Switching window measurements at 40 GHzare shown in Figure 2 with a relative loop de-lay = 3 ps. The window with the SCEAM(width 3.7 ps, extinction ratio 21 dB) is athird shorter than for a single EAM (5.6 ps,19 dB).

When used as an optical time division mul-tiplexing (OTDM) demultiplexer from160 Gbit/s to 40 Gbit/s, the SCEAM has a50 % better temporal detuning range of thedata pulses than a conventional EAM. This isbecause its shorter switching window andhigher extinction ratio give better suppres-sion of the neighbouring channels.

Pulse widths of less than 3 ps wereachieved when using a SCEAM to generateshort optical pulses from a cw signal.

This work is supported by the GermanResearch Fund (DFG) under grant WE1726/4-2.

Enno Hilliger (hilliger@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Self-Cascaded Electro-Absorption Modulator for Improved SwitchingPerformance

The self cascading of an electro-absorption modulator (SCEAM) using commercially avail-able components improves the switching performance of a single electro-absorptionmodulator.

Fig. 1:

Setup of the Self

Cascaded Electro-

Absorption Modulator

(SCEAM)

Fig. 2:

Switching windows

of a SCEAM and a

conventional EAM

63H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Wavelength conversion and 3R regenera-tion (Re-amplification, Re-shaping, Re-tim-ing) will be key functions in future all-opticalnetworks. Wavelength converters using all-optical switches as decision gates can com-bine both functions. A fast decision gate isrequired to realize 3R wavelength conversionat 160 Gbit/s and higher speeds. Phase noisein the data pulses at the inputs of such fastgates is generally transformed to amplitudenoise in the output pulses, which degradesthe regenerator performance.

A pulse shaper to suppress phase-to-ampli-tude noise conversion is incorporated in thefirst 3R wavelength converter to be demon-strated at 160 Gbit/s, to our knowledge [1].It uses ultra-fast switching in a highly nonlin-ear optical fibre. The setup of the pulseshaper is shown in Fig. 1.

An incoming pulse is coupled into a highlybirefringent fibre (HiBi fibre, length 0.5 m,differential group delay 0.85 ps) and recom-bined in a polarization beam splitter (PBS).An output pulse with a flattened top shape(full width at half maximum (FWHM) 2.9 ps)is obtained by adjusting the input polariza-tion and the length of the HiBi fibre. An au-tomatic polarization controller can be usedat the input of the pulse shaper to achievepolarization-independent operation.

Figure 2 shows the experimental setup ofthe 3R regenerating wavelength converter.The 160 GHz optical clock is generated bymultiplexing the signal of a 10 GHz tunablemode-locked laser (TMLL, λ = 1537 nm,1.8 pssech2 pulses). The decision gate was an opti-cal Kerr switch consisting of 1.6 km of HighlyNonlinear Dispersion-Shifted Fibre (HNL-DSF),γ = 20 W-1 km-1, λ0 = 1552.5 nm).

The output pulses of the pulse shaper wereinput into the decision gate as control pulsesto switch clock pulses by cross phase modu-lation (XPM) -induced polarization rotation.The wavelength shifter, based on supercon-tinuum (SC) generation in HNL-DSF (lengthof 850 m, λ0 = 1550.3 nm), was used for ar-bitrary wavelength allocation of the 3R wave-length-converted signal.

The performance of the 3R regeneratingwavelength converter is shown in Fig. 3.Error-free operation for 160 Gbit/s 3R wave-length conversion from λ = 1554 to 1541 nmwas obtained, without significant penaltycompared to a 160 Gbit/s back-to-back mea-surement.

[1] C. Schubert et al., “Improved perfor-mance of a 160 Gb/s all-optical switch usingrectangular gating pulses”, Proc. ECOC ‘02,Copenhagen (DK), Sep. 2002, paper 8.3.7.

Colja Schubert (colja.schubert@hhi.de)

Pulse Shaping for a 160 Gbit/s 3R Wavelength Converter

A 160 Gbit/s all-optical wavelength converter with 3R regenerating capability is demon-strated for the first time. It comprises a simple pulse shaper to form almost rectangulargating pulses and suppress the phase-to-amplitude noise conversion. This pulse shapercan generally be used to reduce the liability to phase noise in fibre-based all-optical gates,even at bit rates above 160 Gbit/s.

Fig. 1:

Schematic of the pulse

shaper

Fig. 2:

Experimental setup for 3R wavelength

conversion

Fig. 3:

BER performance for a

3R wavelength-converted

160 Gbit/s signal (dots),

compared to that of a

160 Gbit/s back-to-back

measurement (crosses)

64

In optical fibre transmission systems, signalregeneration is needed to combat the trans-mission impairments associated with wave-form distortion due to dispersion, fibre non-linearity and noise. Intensity-dependent thresh-old devices, such nonlinear optical loopmirrors (NOLMs), can be applied for noisereduction. A NOLM was operated successful-ly as an intensity filter in a transmission ex-periment using RZ pulses of picosecondwidth. After regeneration by the NOLM thepulses could be transmitted over 160 km ofstandard single mode fibre (SMF) [1].

A schematic of a nonlinear intensity filter isshown in Fig. 1a. The incoming signal is am-plified to a power level close to that of thefundamental soliton and is then split by a90/10 NOLM input coupler into strong andweak components ES and EW, respectively.These components in the right and left circu-lating paths have different nonlinear phaseshifts. The combination of both paths at theNOLM output results in intensity-dependentinterference. As shown in Fig. 1b, the mea-sured transfer characteristics of a NOLM witha SMF has a plateau at input powers close tothe soliton power. Due to this plateau, am-plitude fluctuations (e.g. noise) of the incom-ing signals are reduced at the NOLM output.

In the new NOLM design, we want to re-shape the pulses as well as reduce the noise[2]. To investigate pulse shaping we first cal-

culate the nonlinear pulse propagation onthe SMF. The calculated widths of sech2-pulses travelling along the fibre are shown inFig. 2. The input widths are 2.3, 2.9 and3.5 ps, respectively, corresponding to ±20 %deviation from the mean width. For an aver-age power of 1 dB above the power of thefundamental soliton the pulses are com-pressed due to fibre nonlinearity. We seefrom Fig. 2 that pulses with larger widths arecompressed much more than the narrowpulses. In fact, at L = 0.7 km the variation ofthe pulse widths is minimum.

We utilize this pulse shaping effect to pro-duce an improved intensity filter by choosinga NOLM with a fibre length of 0.7 km andinput power of 1 dB above the soliton pow-er. This NOLM intensity filter achieves bothnoise reduction and pulse shaping, as shownby the calculated eye diagrams at the NOLMinput and output in the inset of Fig. 2.

This work was supported by the EuropeanCommission as part of the IST projectTOPRATE.

[1] R. Ludwig, A. Sizmann, U, Feiste, C.Schubert, M. Kroh, C. M. Weinert and H. G.Weber, “Experimental verification of noisesqueezing by an optical intensity filter forhigh-speed transmission”, ECOC’01,Amsterdam (NL), Paper Tu.B. 2.7.2001.

[2] C.M. Weinert, “Optical intensity filterfor noise squeezing and pulse shaping”,Proc. OFC’02, Anaheim (CA, USA), paperThGG48W, 2002.

Carl M. Weinert (weinert@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Optical Intensity Filter for Noise Squeezing and Pulse Shaping

A new design of a highly asymmetric nonlinear optical loop mirror for the regeneration ofOTDM signals is proposed. It features all-optical noise suppression and pulse reshaping.

Fig. 2: Nonlinear decrease of

pulse width for 2.3, 2.9

and 3.5 ps input widths

Fig. 1:

a) Schematic of a NOLM.

b) Measured transfer

function.

65H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

The implementation and up-grading offlexible and high capacity optical communi-cation networks is expected to be realized inthe long term by the use TDM and WDMsystem technologies. In particular, stable,compact and optimised high speed transmit-ters, available at low cost, are importantbuilding blocks for the application of TDMtransmission and signal processing tech-niques. The availability of high performancemonolithically integrated components is animportant issue, especially for transmissionrates beyond 40 Gb/s.

Monolithic mode-locked laser OEICs onGaInAsP/InP have been fabricated using theHHI integration process [1] and have beencharacterized for passive and hybrid mode-locked operation at 40 GHz. The repetitionfrequency and emission wavelength canboth be finely tuned.

For hybrid mode locking, low timing jitter(220 ± 30 fs), large range of repetition rate(500 MHz) and minimum pulse widths of2.4 ± 0.2 ps have been simultaneously ob-served by changing only the gain currentand the absorber voltage [2]. The pulses arenearly transform limited, and fibre-coupledoutput powers exceeding 0 dBm have beenobtained. Additional frequency shifts are pos-sible by electrical and thermal refractive in-dex changes due to carrier injections into in-tegrated phase and heater sections.

The demonstrated device performance da-ta represent an important step towards theeconomic production of monolithically inte-grated 40 GHz pulse sources for 160 Gb/ssystems.

The work was supported by the FederalMinistry of Education and Research undergrant 01 BP 070.

[1] R. Kaiser and H. Heidrich, “Optoelec-tronic/photonic integrated circuits on InP be-tween technological feasibility and commer-cial success”, IEICE Transactions on Electron-ics, vol. E85-C, no. 4, pp. 970-981, 2002.

[2] R. Kaiser, B. Hüttl, H. Heidrich, S.Fidorra, W. Rehbein, H. Stolpe, R. Stenzel, F.Boczianowski, G. Jacumeit and M. Kroh,“Tunable mode-locked lasers on GaInAsP/InPwith 2 ps pulses and low timing jitter”,Internat. Semiconductor Laser Conf. (ISLC)2002, post-deadline paper #PD2, Garmisch-Partenkirchen (D), 2002.

Helmut Heidrich (heidrich@hhi.de)

Monolithic Mode-Locked Lasers for 160 Gb/s TDM Applications

First mode-locked laser OEICs on GaInAsP/InP for 160 Gb/s hybrid mode locking applica-tions are demonstrated. They feature 40 GHz repetition rate, 2.4 ± 0.2 ps pulse lengths,220 ± 30 fs timing jitter, and more than 0 dBm fibre coupled power.

Fig. 1: Photograph of a mono-lithic mode-locked laser(top view)

Fig. 2: Minimum pulse widthsand required absorbervoltages for passive and

hybrid mode locking at

room temperature

(phase and Distributed

Bragg Reflector( DBR)

sections not biased;

ML: mode locking)

Fig. 3:

Timing jitter and repeti-

tion frequency as func-

tions of gain current for

hybrid mode locking at

room temperature

(biased for minimumpulse width; phase and

DBR sections not biased)

Fig. 4: RF spectrum around subcarrier frequency for

hybrid mode locking at

room temperature

66

Monolithically integrated microring de-vices with optical amplification (OA) take ad-vantage of resonant power enhancement.The signals propagate nearly independentlyclockwise and/or counter-clockwise aroundthe rings. Coupled rings can generate novelfilter functionalities with controlled filter re-sponses. Since the filter quality and reso-nance enhancement are very sensitive to theresonator losses, integrated OAs in each ringare indispensable for high performance cas-caded ring structures.

First OA integrated OADM and flat-top fil-ter devices have been fabricated with a50/100 GHz free spectral range (Fig. 1) [1].All-active devices could be demonstrated, in-cluding single mode emitters, WDM inter-leavers and dispersion compensating filters(Fig. 2) [2]. Furthermore, first cw experi-ments on non-degenerate four-wave mixingindicate a high wavelength conversion effi-ciency (Fig. 3).

This work was supported by the DFG un-der grant HE 3366/2-1 and by the FederalMinistry of Education and Research ofGermany under grant 01 BC 925.

[1] D.G. Rabus, M. Hamacher, H. Heidrichand U. Troppenz, “Box-like filter response oftriple ring resonators with integrated SOAsections based on GaInAsP/InP”, Proc. 14th

Indium Phosphide and Related MaterialsConf. (IPRM '2002), pp. 479-482.

[2] U. Troppenz, M. Hamacher, H. Heidrichand D. G. Rabus: “All-active GaInAsP/InP ringfor widespread functionalities in the wave-length domain”, Proc. 14th Indium Phosphideand Related Materials Conf. (IPRM '2002),pp. 475-478.

Helmut Heidrich (heidrich@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Multifunctional Optical Amplifying Microring Resonators for Integrationin Photonic ICs

Monolithically integrated active ring resonators may become a viable approach for opticalsignal processing at rates up to a few tens of gigabits per second for WDM applications(e.g. filtering, Optical Add-Drop-Multiplexer (OADM), wavelength conversion) and forTDM switching. Evaluation of their potential and limits is a main issue.

Fig. 2:

Micrograph of an all-

active ring resonator

device with contacted

feeding, coupler, and

ring sections

Fig. 3:

All-optical channelswitching experiment.The signal wavelength

λS was kept fixed whilethe pump wavelength λP

was varied in multiples

of the Free Spectral

Range (FSR) of the ringresonator. The shaded

areas indicate the

converted wave.

Fig. 1: Micrograph of a triple

ring resonator with integrated OA sectionsand heaters to trim the

separate rings

67H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

The implementation of low-cost transmit-ter modules for fibre-optic applications re-quires efficient coupling of the light from thelaser light source into a single mode fibre.This can be achieved by incorporating aspot-size converter into the laser that basical-ly relies on a tapered waveguide structure.We have previously developed such lasers asFabry-Perot devices employing the conceptof a tapered active stripe in conjunction witha buried heterostructure (BH) design [1]. Thisconcept offers the advantage, amongst oth-ers, of realizing tapered lasers with relativelyshort cavities (< 500 µm), thus allowing alarge number of devices to be accommodat-ed on a wafer.

In the present work we have successfullyextended this approach to DFB-type lasers.This is difficult because, due to the tapereddesign of the active stripe, the index of re-fraction determining the Bragg wavelengthfor a given DFB grating varies along the lasercavity (Fig. 1). Hence, in order to achieve sin-gle mode behaviour the Bragg grating peri-od must be chirped according to this varia-tion (Fig. 2). As a result, the grating perioddecreases from the front of the taper (lowneff) to the back of the taper (high neff), withpitch variations of the order of only 10-3 nm.

To accomplish such extremely demandingchirped gratings we applied a novel electronbeam lithography method developed recent-ly in our group [2]. Instead of using the con-ventional beam addressing scheme, which isgenerally limited to a resolution of a fewnanometers, additional correctional elementsfor beam deflection in the e-beam systemhave been used as a repeatedly movedvernier. In this way it is possible to generatealmost any grating period that can be ex-pressed analytically.

Figure 3 shows the optical output powerof upside-up mounted lasers, the front facetsof which are AR-coated while the back facetsare left as-cleaved. More than 60 mW of CWoutput power has been achieved. This valueis equivalent to the optical output power ofcomparable lasers with a straight activestripe. The measured side-mode suppressionratio (SMSR) was more than 50 dB at100 mA. The far-field angles (FWHM) are 14°in the lateral and 20° in the vertical direction.Compared to non-tapered DFB lasers of thesame heterostructure design, these valuesmean a reduction of more than 12° in bothdirections. Lasers from different laser-bars in-dicate a single mode yield of more than70 %, which is distinctly higher than com-monly achieved with straight DFB lasers ofotherwise the same design.

[1] M. Möhrle et al., Proc. 14th IPRM 2002,Stockholm, Sweden, pp. 27-30.

[2] R. Steingrüber et al., MicroelectronicEngineering, vol. 61-62, pp. 331-335, 2002.

Martin Möhrle (moehrle@hhi.de)

All-Active Tapered 1.55 µm Index-Coupled InGaAsP BH-DFB Lasers WithContinuously Chirped Grating

All-active tapered 1.55 µm index-coupled InGaAsP BH-DFB lasers incorporating a continu-ously chirped grating have been realized for the first time. The lasers have large opticaloutput powers, small far fields and high single mode yield.

Fig. 2: Optimized distribution

of grating period along

the tapered stripe

Fig. 1: Calculated effective

refractive index neff as a

function of the positionx in the tapered stripe

Fig. 3:

Output power and spectrum of tapered

DFB-BH laser

68

Despite the present downturn in thetelecommunication industry, there is an in-creasing demand for fast external modula-tors for 40 Gbit/s NRZ and RZ formats. Thereis also an increasing interest in new modula-tion formats such as carrier-suppressed RZ(CS-RZ) or differential phase shift keying (DP-SK). Indium phosphide (InP) modulatorsbased on a Mach-Zehnder interferometer(MZI) structure with a travelling wave elec-trode (TWE) design can deliver high datarates of 40 Gbit/s and beyond, as well as ze-ro-chirp designs and an optical bandwidth of30 nm. In addition, due to the highly effi-cient quantum-confined Stark effect (QCSE)used for the modulator, its structure is muchsmaller (< 3 mm2) and needs less drivingvoltage (Vpp ≈ 2V) than comparable devicesmade with GaAs or lithium niobate. This in-herently low driving voltage is one of its keyassets at future transmission rates of 80 Gbit/sand above.

Once developed, modulation formats oth-er than RZ and NRZ, such as CS-RZ or DPSK,can be handled with little structural changes.

The schematic layout of the modulator isshown in Fig. 1. The two TWE electrodes aredesigned as coplanar waveguides. Their over-all impedance can be matched to 50 Ω bythe capacitive load of the distributed elec-trodes in the MZ arms.

The cross-section of an MZI sector isshown in Fig. 2. The layers with the variousmaterial sequences are shown schematically.

The electro-optical response of this devicecan be seen in Fig. 3. An electro-opticalbandwidth of 42 GHz has been achievedwith this design at a period length of

500 µm for the capacitive loads, but furtherimprovements up to modulation speeds of160 Gbit/s should be possible with this ap-proach.

The optical design of this modulator in-cludes an optical-mode transformer for cou-pling to cleaved fibres with low insertionloss. The incorporation of this etched spotsize converter in the manufacturing processand the selective chemical etching of theplatinum in the metal top contact have beenthe key achievements in this successful devel-opment.

Current developments include a hybrid in-tegration of the modulator together with thedriver electronics. Further improvements fortransmission rates up to 80 – 160 Gbit/s areexpected if the modulator and the dedicatedelectronics for hybrid integration are realizedtogether.

This work was supported by the FederalMinistry of Education and Research undergrants 01 AK 936B and 01 BP 273.

Karl-Otto Velthaus (velthaus@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Development of a Broadband InP-Based Mach-Zehnder Modulator withElectro-Optical Bandwidth Greater Than 40 GHz

An InP-based Mach-Zehnder-modulator with an optical-mode transformer and an electro-optical bandwidth above 40 GHz has been developed. The fabrication process is designedto achieve good reproducibility and high yield. Current research activities are directed to-wards higher bitrates of 80 – 160 Gbit/s. A hybrid integration of a driver IC into a modu-lator module is also under development.

Fig. 2: Perspective view of an

MZI sector with capaci-tively loaded TWEs via

air-bridge contacts

Fig. 3:

Electro-optical response

measured by a fast

photodiode

Fig. 1: Schematic layout of an

MZI-based modulatorwith capacitively loaded

travelling wave electrodes

69H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Future cost-efficient WDM devices basedon planar photonic crystals would combinehigh density integration (sharp bends, split-ters, etc.) with novel active functionality(tunable dispersion, enhancement of nonlin-earity, etc.). However, the major challengesare to achieve low propagation losses due tooff-plane scattering at imperfections and lowcoupling losses due to Fresnel reflections atinterfaces.

To tackle the scattering problem a reliableetching process for extremely large aspectratios is needed. Therefore a two-step etch-ing process is necessary, starting with theetching of an intermediate mask (e.g. SiNx).The hole patterns are defined by electronbeam lithography [1], which is still requiredfor the fabrication of thick and highly resis-tive masks.

Chemically assisted ion beam etching(CAIBE) is a suitable tool for the final crucialdeep etching step (Fig. 1). In this techniquea drastic RIE lag making very small structuresvery shallow is not present. In this way muchlarger aspect ratios than with standard RIE(reactive ion etching) can be obtained (Fig. 2),thus exponentially decreasing the scatteringlosses in PhC waveguides.

Two adiabatic field transformers [2] areused for efficient coupling from an optical fi-bre to a PhC waveguide. First a planaradapter section transforms from the fibre in-terfacing facet to a standard optical boardwaveguide. Then a field transformer with avertical taper section is used for coupling in-to the PhC (Fig. 3). This design allows for thecompensation of effective index contrast and

field width mismatch (about 500 nm in PhCwaveguide with one missing row).

The work is supported by the FederalMinistry of Education and Research undergrant 13B82428.

[1] R. Steingrüber, S. Golka and H.Heidrich, “Useful and cost efficient fabrica-tion of dot arrays for photonic crystals by di-rect write electron-beam lithography”, Proc.MNE ‘02, Lugano, Switzerland, September2002, pp. 138-39.

[2] H. Heidrich and C. M. Weinert: “Inte-griert optischer Feldweitentransformator zuradiabatischen monomodigen Feldanpas-sung”, Patent Application DE 10123137C1(30.4.2001).

Sebastian Golka (golka@hhi.de)

Nanotechnology for the Fabrication of Planar InGaAsP/InP PhotonicCrystal Devices

The use of planar Photonic Crystal (PhC) ICs is one of the most promising approaches forminiaturizing monolithically integrated photonic devices. The focus of this work is on ob-taining frequency dispersion in the bulk of such PhCs. A very demanding fabricationprocess is required.

Fig. 1: SEM image of deeplyetched PhC material fab-

ricated using chemically

assisted ion beam etch-ing (CAIBE). The pitch is420 nm. The field of the

planar waveguide mode

is sketched at the left.

Fig. 2: Structure depthachieved by two CAIBEprocesses, with high (triangle) and low (circle) chemical contributions

Fig. 3:

Schematic of an

adiabatic field

transformer

70

A balanced photodetector is a key elementfor direct detection in differential phase shiftkeying (DPSK) transmission formats in whicha bipolar reception scheme is desired. Mono-lithically integrated balanced waveguidephotodetectors provide excellent RF match-ing of both photodiodes, broad bandwidth,high power capability and low packagingcost. The design of the integrated balancedphotodetector based on InP is shown sche-matically in Figure 1. It contains two spot-size transformers, two waveguide S-bendsand a pair of high-speed pin photodiodes(PD1 and PD2) with high power capability.The evanescently coupled photodiodes arelocated on top of the waveguide layer stackand are biased by integrated bias circuits.The photodiodes are electrically connectedin an anti-parallel configuration; with thecurrents subtracted directly on chip. This im-proves the RF performance at high frequen-cies.

Figure 2 shows the packaged balanced de-tector module, with two fibre input connec-tors, two pins for biasing and the coaxialoutput port. The detector has an electrical3 dB cutoff frequency of 34 GHz and narrowpulse widths of 15 ps. Experiments demon-strate a high degree of symmetry betweenthe photodiodes up to signal frequencies of30 GHz, which is due to our compact mono-lithic integration scheme. This results in abroadband common-mode rejection ratio ofmore than 20 dB [1].

We tested the detector in first experimentswith a DPSK modulation format at 40 Gbit/s,using a zero-biased Mach-Zehnder modula-tor in push-pull configuration and an opticaldelay line demodulator. The received eyepattern of a pseudo-random bit stream oflength 215-1 at an input power of 10 dBm isclearly open (Figure 3). The receiver sensitivi-ty for BER = 10-9 is better than -29 dBm.

[1] A. Beling, H.-G. Bach, D. Schmidt, G.G.Mekonnen, M. Rohde, L. Molle, H. Ehlersand A. Umbach, “High-speed balanced pho-todetector module with 20 dB broadbandcommon-mode rejection ratio”, Proc. OpticalFiber Commun. (OFC 2003), March 23-28,2003, Atlanta (GA, USA), paper WF4.

Andreas Beling (beling@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

40 Gbit/s Balanced Photodetector Module Based on InP

A high speed monolithically integrated balanced photodetector is presented. The detec-tor module has a 3 dB bandwidth of 34 GHz and a broadband common-mode rejectionratio of more than 20 dB, and is suitable for operation in 40 Gbit/s transmission systems.

Fig. 1:

Schematic view of the

integrated balanced

photodetector

Fig. 2: Balanced photodetector

module

Fig. 3:

Eye diagram of a

40 Gbit/s DPSK bit

stream (10 ps/div,

30 mV/div)

71H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Although there is a continuing trend toupgrade the world-wide high-speed trans-mission core networks to bit rates of40 Gbit/s, even higher rates are of interest tooptimise the transport capacities of the fibrenetworks. Monolithic opto-electronic inte-grated receivers based on InP, operating at awavelength of 1.55 mm, are the mostpromising candidates for high bitrate trans-mission systems at 40 Gbit/s and beyond.

Figure 1 shows the circuit design of thepinTWA [1] photoreceiver OEIC. A newlyadded metal-insulator-metal (MIM) capacitor(100 pF) separates the dc potentials of theamplifier ground and the high frequencyoutput. The output can be adjusted to zerobias or to an arbitrary potential, dependingon the needs of the subsequent electronics.

The InP-based photoreceiver is realized byintegrating a waveguide-integrated photodi-ode together with a spot-size converter anda special high-electron mobility field effecttransistor (HEMT)-based travelling wave am-plifier (TWA). The OEICs were fabricated us-ing a two-step MOVPE/MBE epitaxial ap-proach for the waveguide-integrated photo-diode HEMT layer stacks, thereby allowingthe individual devices to be independentlyoptimised. Figure 2 shows the fabricated OEIC.

Characterization was done by the opticalheterodyne measurement technique. Thebandwidth exceeded 50 GHz.

Figure 3 shows the measured eye patternat 40 Gbit/s. The eye is wide open, so thathigher bitrate capability may be presumed.

Due to the lack of measurement capabili-ties at higher bitrates, the eye pattern was

deduced synthetically by FFT/IFFT methodsin a circuit simulator. The minimum phase ofthe receiver was calculated from the mea-sured magnitude response using the Hilberttransform, and this was then used to deriveeye patterns at arbitrary bit rates (Fig. 4).Even at 60 Gbit/s the eye is well opened, andthe STM64 mask is unaffected.

[1] H.-G. Bach, A. Beling, G. G. Mekonnenand W. Schlaak, “Design and fabrication of60 Gbit/s InP-based monolithic photoreceiv-er OEICs and modules”, IEEE J. Select. TopicsQuantum Electron. (Issue: Integrated Opticsand Optoelectronics), vol. 8, pp. 1445-1450,Nov./Dec. 2002.

Heinz-Gunter Bach (bach@hhi.de)

60 Gbit/s Photoreceiver Modules using InP OEICs for Direct Interfacing toa Demultiplexer Without a Bias-T

A fully packaged InP-based photoreceiver, comprising a waveguide-integrated photodi-ode and a travelling wave amplifier, is presented. The interface to the following electron-ics is dc-coupled, which avoids the usual bias-T. It functions at data rates up to 60 Gbit/swith NRZ modulation.

Fig. 1:

Circuit schematic of the

pinTWA photoreceiver

OEIC with a dc-coupled

output to the following

electronics. The dc

decoupling of two

ground potentials of the

OEIC is provided by the

integrated 100 pF MIMblocking capacitor.

Fig. 4: Calculated eye patternat 60 Gbit/s using NRZ

modulation (1024 bits)

Fig. 2: Photoreceiver OEIC withRF and dc ground padsdecoupled by MIM capacitors (dotted whiteline)

Fig. 3:

Measured 40 Gbit/s NRZ

eye pattern of the

photoreceiver module at

-1.6 dBm using a PRBS of

length 231-1

72

Packaging of laser OEICs in lead frametechnology for plastic SMT packages (e.g.TSSOP10) is a novel, less expensive approachas compared to the use of metal housingssuch as butterfly, DIL or TO. In SMT pack-ages the beam of an edge-emitting laser chipis directed via prisms or mirrors so that itemits at right angles to the mounting plane.

We realized a complete monolithic solu-tion including a 1.3 µm buried heterostruc-ture Fabry-Perot (BH-FP) laser, an opticalfield transformer to reduce the far-field angleto less than 22° at 3 dB, a 45° beam reflectorfor bottom emission and a monitor photodi-ode in the beam propagation direction(Fig. 1) [1]. The fabrication of the laser andreflection mirrors in full-wafer technology re-duces cost due to on-wafer facet preparationand on-wafer characterization.

Fabrication starts with standard BH-FP laserprocessing. The photodiode epitaxial layerstack is grown together with the laser clad-ding layer. The laser resonators and photodi-ode mirrors are then etched using a chlorine-based chemically assisted ion beam etchingprocess (CAIBE) (Fig. 2). Aging measure-ments show no degradation due to theetched mirrors. Lifetimes exceeding 105 hoursare estimated by extrapolation.

The 45° totally reflecting mirrors areetched at low temperature with an accuracybetter than 1° using an HBr:HCl solution. Theantireflection coating of the photodiode in-put side and the reflection coating of thelaser backside are deposited on-wafer. Thecomplete element is sealed with photosensi-tive CYCLOTENE™ 4000 series from DOW,which reduces the far-field laser angle due toits refractive index (1.54).

The photodiode current corresponding toa laser output power of 10 mW is 1.5 mA.The responsivity of the monitor photodiodewas nearly constant at 0.13 A/W over a 40 mArange of laser current (Fig. 3). The photodi-ode dark currents are less than 20 nA at 5 V.

The die size and overall performance arecomparable to hybrid solutions.

This work was performed under a subcon-tract from Infineon Technologies AG.

[1] K. Janiak, P. Albrecht, S. Fidorra, H.Heidrich, W. Rehbein, H. Roehle and H.-L.Althaus, “1.3 µm BH-FP laser with integratedmonitor photodiode, 45° reflector for bot-tom side emission employing full on-waferfabrication”, Proc. IPRM 2002, May 2002,Stockholm, Sweden, pp. 31-34, paperMoA1-4, ISBN 0-7803-7320-0.

Klemens Janiak (janiak@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Full On-Wafer Fabrication of a Bottom-Emitting 1.3 µm BuriedHeterostructure Fabry-Perot Laser with Integrated 45° Reflector andMonitor Photodiode

We realized a bottom-emitting OEIC, including laser, monitor photodiode, and prism, in amonolithic integrated form suitable for surface mount technology (SMT) packaging. Thefabrication of the laser and the reflection mirrors in full-wafer technology exploits thecost-efficiency advantages of on-wafer facet preparation and on-wafer characterization.

Fig. 1: Device architecture

(HR/AR: highly reflective/antireflective coating)

Fig. 2:

SEM view of CAIBE-

etched front-side Fabry-

Perot resonator and

photodiode

Fig. 3:

Bottom side laser output

power and monitor

photodiode current

73H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

The fabrication of nanoscale multiple two-dimensional dot arrays is becoming increas-ingly important because they are the essen-tial constituents of Photonic Crystals (PhC).The characteristics of PhCs depend cruciallyon the shape and size of the dots. Thereforedirect-write electron beam lithography (EBL)is the technology of choice for generatingthese structures. Typical PhC dot arrays usepitch sizes and diameters of only a few hun-dred nanometers arranged in a hexagonalgrid, and this pattern will extend over vari-ous sub-devices in future integrated PhCcomponents.

The design aspects of PhCs place high de-mands on data generation and preparationdue to the enormous amount of CAD andexposure data required. In our approach wetake advantage of the proximity effect dur-ing the exposure [1, 2]. This allows us to userectangularly defined dot shapes instead ofcircular ones.

The top sequence in Fig. 1 shows the cal-culated dependence of the nominally circulardot shapes on the chosen resolution duringfracturing. The shape of the dots is lost if acoarser resolution is used. In contrast to that,the lower sequence of Fig. 1 shows that forrectangular dots there is no dependence ofthe shape on the chosen converter addressgrid. Whereas for circular shapes the amountof data increases quadratically with the ap-plied resolution, we found that for rectangu-lar design the size of the exposure data set isnot affected. This simplifies the data man-agement, e.g. proximity correction or doseassignment.

For fabrication by EBL we use a standardvector scan tool and standard high resolutionresists. We found best results for a ratio ofdesign width to pitch of 0.4. For example, a250 nm pitch requires a 100 nm square de-sign width. Figure 2 shows a two-dimension-al dot array stripe in resist fabricated usingthe optimised processing conditions.

This work was supported by the FederalMinistry of Education and Research ofGermany under grant 13B82428.

[1] R. Steingrüber, S. Golka, and H.Heidrich, “Useful and cost efficient fabrica-tion of dot arrays for photonic crystals by di-rect write electron-beam lithography”, Proc.MNE ‘02, Lugano, Switzerland, September2002, pp. 138-139.

[2] R. Steingrüber, patent application102 43 827.7, 14.09.2002.

Ralf Steingrüber (steingrueber@hhi.de)

A New Approach to the Fabrication of Nanoscale Dot Arrays using Direct-Write Electron Beam Lithography

An easy-to-use procedure for the generation of complex nanoscale two-dimensional dotarrays is presented. The dot elements of the designed patterns are defined as squares in-stead of circular shapes, which results in a dramatic reduction of the data volume andcomplexity. Under optimised process conditions the use of rectangularly defined dots re-sults in circular pattern shapes of well controlled dimensions.

Fig. 1: Calculated shapes of circular and rectangulardots for different resolutions

Fig. 2:

SEM photograph of a

dot array in resist

74

Photonic crystals (PhC) are artificial period-ic structures with high refractive index con-trast in which the periodicity is on the scaleof the wavelength of light. Photons travellingthrough such a lattice encounter a band ofwavelengths which cannot propagate andwhich are therefore completely reflected.This photonic bandgap (PBG) behaviour isanalogous to the electronic bandgap forelectrons travelling through the periodic po-tential of a semiconductor lattice. PBG mate-rials also offer a method of realizing highlyconfined optical states by the insertion of lo-cal defects into a PhC. These constitute reso-nant cavity modes and appear as sharptransmission lines inside the forbidden band.

Photonic crystals have attracted great in-terest because of their potential to controllight wave propagation and to implementPhC-based optical filters in WDM systems.Since 3D PhCs are difficult to fabricate, an al-ternative is to use waveguides for lateral lightconfinement, combined with a periodic arrayof holes which forms a linear PhC. A defectincluded in this PBG structure can create alocal cavity mode that can act as an opticalfilter.

Extending the optical waveguides at bothsides of the PhC gives efficient light couplingto the PhC micro-cavity. Unlike 3D photonicmicro-cavities, light confined in an index-guided structure also couples to radiationmodes, leading to increased loss in the trans-mission lines. These structures must thereforebe designed carefully to realize cavities withhigh quality and low losses.

We have calculated the PhC micro-cavitybehaviour in single-mode SOI waveguideswith air-filled holes using the 3D FDTD (finitedifferential time domain) method. Figure 1shows for example the calculated transmis-sion behaviour of a row of 2 x 4 holes (with a450 nm period and a 650 nm gap betweenthe groups) in a 200 nm thick and 500 nmwide silicon strip waveguide. The hole diam-eters vary between 200 nm and 250 nm, re-sulting in a bandgap of about 400 nm [1].

Figure 2 is a REM picture of a PhC micro-cavity structure fabricated in SOI (200 nm sil-icon layer on top of 2 µm thick SiO2) by e-beam writing and anisotropic etching. The

etched holes are about 500 nm deep and250 nm in diameter.

The sample transmission was measured inthe wavelength range 1450-1550 nm usinga tunable laser source. The result is shown inFig. 3, in which a transmission peak at 1475nm is evident.

[1] G. Przyrembel, B. Kuhlow and S.Schlüter, “Flat-top transmission waveguidefilter with multiple cavities”, Proc. Workshopand EOS Topical Meeting on 2D PhotonicCrystals, pp. I-20, Ascona (CH), Aug. 25-30,2002.

Berndt Kuhlow (kuhlow@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Silicon-on-Insulator Photonic Crystal Structures for WDM Applications

Filter components are realised that are based on micro-cavities formed by deliberate de-fects in linear photonic crystals patterned in high index waveguides. The photonic crystalstructures are fabricated in silicon-on-insulator (SOI) technology by direct e-beam writingand etching.

Fig. 2:

REM picture of a fabri-

cated PhC micro-cavity

structure in SOI with

2 x 3 holes and a gap

between them

Fig. 3: Measured filter

behaviour of a PhC

micro-cavity in SOI with2 x 4 holes and a gap

size of 640 nm

Fig. 1: Calculated transmissionof a linear hole grating

with defects in a single-mode SOI waveguide

75H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

The utilization of intersubband transitionsin semiconductor multiple quantum wells(MQW) is attractive for realizing ultra-fastphotonic devices due to their ultra short car-rier relaxation times and the pronounced op-tical nonlinearities inherent in these transi-tions. Light sources, optical amplifiers andoptical switches for ultra-high bitrate opticalfibre transmission might possibly be realizedby employing intersubband transitions. Inthis context HHI is member of the Berlin-based joint research group “Light emittersbased on intersubband transitions”, whichaims to achieve a detailed understanding ofintersubband emitter structures as well astheir implementation in devices (QCLs).

In the first stage of research, MBE growthand processing technology for QCLs weredeveloped using the design in [1] for con-ventional strained GaInAs/AlInAs layers onInP. Early 27 µm wide devices showed laseremission up to 300 K (Fig. 1) with a 300 Kthreshold of 3.8 A (pulsed).

Using GaInAs/AlInAs QCL structures, evenwith strained layers, the emission wavelengthis limited to IR wavelengths above 3.5 µm. Inprinciple, this wavelength range could be ex-tended to shorter values, approaching1.55 µm, which are relevant for fibre-basedcommunication, by incorporating barrier ma-terials with larger band gaps in the QCL ac-tive region. On InP a potential candidate isAlAsSb (lattice-matched at xSb = 0.44), whichdue to its large band gap has a conductionband edge discontinuity of roughly 1.7 eV.An intersubband transition wavelength of

1.55 µm has recently been deduced from IRabsorption for such MQWs [2].

We have achieved first lattice-matchedGaInAs/AlAsSb MQWs with well thicknessesbetween 2 nm and 4 nm that are adequatefor 1.55 µm intersubband transitions. Theperfect agreement between the measuredand modelled x-ray diffraction spectra inFig. 2 indicates the high quality of the epi-taxial layers. In addition, based on the agree-ment between 300 K photoluminescencemeasurements and simple calculations (e.g.using the parabolic approach), the electronicstructure of the GaInAs/AlAsSb MQWs wasinvestigated. Thus, the MBE growth basis forreduced wavelength QCLs and terabit persecond all-optical switches has been estab-lished.

This work is sponsored by Deutsche For-schungsgemeinschaft (DFG) as FOR394 andwas performed partially in collaboration withthe TU Wien.

[1] D. Hofstätter, M. Beck, T. Aellen and J.Faist, Appl. Phys. Lett., 78, 396 (2001).

[2] T. Mozume, H. Yoshida, A. Neogi andM. Kudo, Jpn. J. Appl. Phys., 38, 1286(1999).

Harald Künzel (kuenzel@hhi.de)

Intersubband Emitters Based on InP

Intersubband transitions in multiple quantum well structures are attractive for long-wave-length emitters (quantum cascade lasers) and potentially also for ultra-fast optical switch-es and optical amplifiers in telecom applications. Quantum cascade laser (QCL) devicesoperating at 5 µm wavelength and up to 300 K have been fabricated in GaInAs/AlInAstechnology. To shift the wavelength towards 1.55 µm for fibre-based communication,molecular beam epitaxy growth of GaInAs/AlAsSb quantum wells on InP has been com-menced.

Fig. 1: 300 K laser spectrum ofa strained GaInAs/AlnAs

QCL (with pulsed

excitation

Fig. 2: X-ray diffraction patternof a 50-period 3 nm/30 nm GaInAs/AlAsSb

MQW

(grey line: measured,

black line: modelled)

76

WDM demultiplexer components featuringtemperature-independent wavelength chan-nels are highly attractive for cost reasons.Recently we have introduced such a demulti-plexer based on an athermal arrayed wave-guide (AWG) built entirely on polymer mate-rials [1]. A key issue arising with such ather-mal AWGs is, however, the fine tuning of thewavelength channels to the standard ITUgrid. Conventional adjustment techniquesbased on heaters or coolers are not useful forthis purpose. We have therefore investigatedgamma (γ) irradiation as a potentially power-ful trimming method.

The central wavelength of an AWG is givenby:

λc = nc · ∆L/m,where λc is the central wavelength, nc the

effective refractive index of the arrayedwaveguide, ∆L the path length difference be-tween neighbouring waveguides, and m thegrating order. It is apparent that the centralwavelength is essentially determined by theeffective refractive index of the waveguide.The use of γ-rays was considered an efficientway to modify this parameter and thus theAWG wavelength.

All-polymer athermal 8 x 8 AWG routerswith ∆λ = 200 GHz at λ = 1.55 µm were pro-duced by properly matching the coefficientof thermal expansion of the polymer sub-strate to the thermo-optic coefficient of thepolymer waveguide. Gamma irradiation wasapplied to the completed chips. Figure 1shows the measured results of the indexchange as a function of the γ-ray dosage. Anindex increment of 0.003 was obtained at aγ-ray dose of 200 kGy/cm2. Respective trim-ming results for an AWG router are shown inFig. 2. A wavelength shift of 1.7 nm was ob-tained at a γ-ray dose of 213 kGy/cm2 [2].This wavelength shift is larger than the chan-nel spacing of a 200 GHz AWG.

The measured excess insertion loss due toγ-ray irradiation is shown in Fig. 3. The in-duced extra loss can be seen to be less than0.3 dB for a 200 GHz AWG, requiring aworst-case trimming range of 100 GHz.

This work was performed in cooperationwith FhG IZM/EPC, Teltow, Germany, andwith Gamma Bestrahlung GmbH, Radeberg,Germany, and was partially supported by theFederal Ministry of Education and Researchunder grant 01 BP 150.

[1] N. Keil et al., Conf. Dig. OFC 2001,Post-Deadline Session, PD7, 2001.

[2] N. Keil et al., Conf. Dig. ECOC 2002,6.2.3, 2002.

Norbert Keil (keil@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · P H O T O N I C N E T W O R K S

Wavelength Trimming of All-Polymer Athermal Arrayed WaveguideMultiplexers

A novel post-fabrication refractive index trimming technique is reported for adjusting thecentral wavelengths of all-polymer athermal arrayed waveguide grating multiplexers tothe standard ITU frequency grid.

Fig. 1: Effect of γ irradiation on

refractive index

Fig. 2:

Wavelength shift of an

AWG as a function of the

γ-ray dose

Fig. 3:

Irradiation effect on insertion loss

77H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Recent results from information theoryhave shown that the capacity of radio sys-tems may be increased linearly with thenumber of antennas when multiple antennasare used at both the transmitter (Tx) and re-ceiver (Rx) and when the Rayleigh fading be-tween pairs of antennas is independent.

In order to evaluate the potential of MIMOtechniques, channel measurements were con-ducted at HHI in cooperation with MEDAVGmbH, Uttenreuth.

The antenna arrangement is shown in Fig. 1.The basic element is a λ/4 monopole withomni-directional characteristic. We use 3 mo-nopoles forming a triple antenna to exploitthe independence of the fading field compo-nents (top left). Monopoles could be re-placed by patch antennas in practical appli-cations (top right). A triple antenna is mount-ed at each corner of a laptop-like chassis sothat the equally directed elements have largespacings and the fading tends towards inde-pendence (bottom). The arrangements atthe transmitter and receiver were similar.

Individual channels between each pair ofTx and Rx antennas were measured with theRUSK ATM channel sounder in the 5.14 –5.26 GHz frequency range. All channels weremeasured in a total time of only 1 ms, whichis short compared to the time in which chan-

nel properties may change. The MIMO ca-pacity was obtained from the measurementdata of a static configuration after averagingover 50 snapshots to reduce the noise. Typi-cal measured SNR values are in the 35– 45 dBrange to reliably estimate the capacity forlink SNR values up to 20 dB. The mean pathloss was averaged out to compare the mea-surements with the theory.

The measurement results are shown in Fig. 2.The dotted line shows the theoretical valuesfor independent Rayleigh fading. The full cir-cles are the measured results when the LOSwas blocked by an absorber mat with morethan 20 dB attenuation. The measurementsagree very well with the theoretical results inthe absence of a LOS signal. Spectral efficien-cies better than 80 bps/Hz are indeedachievable at reasonable link SNRs (20 dB)with 16 transmit and receive antennas.When the LOS is included, some minordegradation is observed if there are morethan 10 antennas.

Even at relatively small distances betweenTx and Rx antennas (1 m), the increase ofcorrelation due to the LOS signal remainssmall. This is related to the somewhat unex-pected fact that scattering is quite significantwith omni-directional antennas, so that thedirect signal is not as important. Note thatthe antenna arrangement has a large impacton the achievable capacity [1].

[1] V. Jungnickel et al., Proc. WPMC, 27-30October, 2002, Honolulu, Hawaii.

Volker Jungnickel (jungnickel@hhi.de)

Measurements of the Capacity of MIMO Radio Systems in IndoorEnvironments

Measurements of the capacity of Multiple-Input Multiple-Output (MIMO) radio systemswith large numbers of antennas were conducted at 5.2 GHz. With triple antennas at thecorners of a laptop-like chassis, a linear relation between the capacity and the number ofantennas was observed in non-line-of-sight (NLOS) environments, consistent with resultsfrom information theory. The degradation due to the line-of-sight (LOS) signal is usuallysmall when antenna elements have omni-directional characteristics.

Fig. 1:

Antenna arrangementsused for MIMO channel

measurements

Fig. 2: Measured MIMO capacity as a function ofthe number of antennas

78

It is well known that the capacity of MIMOsystems may be reduced when there is littlescattering. The channel matrix H describingthe transmission from each transmit (Tx) toeach receive (Rx) antenna may then be sin-gular. Consider the well known singular val-ue decomposition H = U · D · VH, where Uand V are unitary matrices, D is a diagonalmatrix with ordered singular values (SVs) onthe main diagonal, and the superscript H in-dicates the hermitian transposition. We ob-serve that one or more SVs are close to zerowhen scattering is rare, so that H is close tosingular in this case. There will be no pseu-do-inverse matrix enabling separation of da-ta streams sent in parallel over that MIMOchannel.

Reduced complexity MIMO processingschemes based on the pseudo-inverse ma-trix, such as V-BLAST, must therefore be ex-tended by bit loading algorithms applyingadaptive coding and modulation in eachstream. But still, only a single stream may betransmitted in a truly singular channel.

In wireless systems operating in time-divi-sion duplex mode (e.g. UMTS-TDD and802.11), CSI for the downlink may be ob-tained from the uplink, and vice versa, usingchannel reciprocity.

In this case we can employ ACI for reliabletransmission of multiple streams. This tech-nique is based on the well known “eigen-mode signalling” method in which each datastream is assigned to a corresponding SV bypre-processing the data vector dred byx = V · D-1 · dred, where x is the Tx signalvector and D-1 is the pseudo-inverse of D,and then post-processing the Rx signal vec-tor y by dred’ = UH · y.

The length of the data vector dred, i.e. thenumber of active streams nd, may then bechosen to maximize the throughput. In thisway data signals will not be assigned to thecritical singular values close to zero.

The capacity of ACI with optimal nd iscompared in Fig. 1 to the ultimate water-fill-ing (WF) and linear inversion (LCI) methods,where nd is maximal. Obviously, ACI approx-imates WF at low power, where only a singlestream at full power is supported by either

scheme. Also, higher power is required for agiven capacity with LCI because of the smallSVs [1]. Clearly, avoiding critical SVs by re-ducing nd increases the capacity.

ACI also allows a step-wise trade-off be-tween spatial multiplexing (i.e. parallel trans-mission of data streams) and diversity, asshown in Fig. 2. When the maximum num-ber of streams is used, a huge power is need-ed to achieve a small bit error rate, and theslope of the curve indicating diversity order israther small. But as soon as one or morestreams are switched off, much less power isneeded and the diversity order is significantlyincreased. Transmission is more reliable inthat case.

[1] V. Jungnickel et al., GLOBECOM, 17-21November 2002, Taipeh, Taiwan.

Volker Jungnickel (jungnickel@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Adaptive Signal Processing for Singular MIMO Channels

MIMO capacity may be reduced in propagation scenarios where there is little scattering.By using well known reduced-complexity signal processing algorithms, such as V-BLAST,the probability of outage may become rather large in such channels. Adaptive channel in-version (ACI) is a simple scheme to combat these problems, provided that channel stateinformation (CSI) is available also at the transmitter.

Fig. 1: Mean MIMO capacity fordifferent pre-processing

schemes

Fig. 2:

Bit error rate of ACI

with reduced numbers

of streams nd

79H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Fourth generation mobile systems must bedesigned to meet the ever-increasing de-mand for bandwidth in a flexible and low-cost manner, and the combination of OFDMand MIMO appears to be a promising candi-date for this application. There are two mainreasons underlying this assertion: multiple an-tennas were recently shown to increase theoverall capacity to enormous values, whileOFDM provides scalable and flexible trans-mission and, most importantly, requires onlya very simple equalisation scheme. However,major obstacles to the deployment of this ca-pacity are: 1) the high PAPR of the transmit-ted signal, and 2) channel impairments dueto user mobility.

The main disadvantage of OFDM transmis-sion is the high PAPR. For example, if thepeak power is limited by a regulatory body,the average power allowed under OFDM islower than with constant power modulation.Moreover, the transmitter power amplifiermust operate in a power-inefficient region.Also, limited output back-off causes clippingof the transmitted signals, leading to spectralre-growth and increased bit error rates.

The clipping rate depends on the statisticaldistribution of the PAPR of the OFDM sig-nals. In [1, 2] a new approach was presentedthat can be used to bound the distribution ofthe PAPR for both uncoded and coded sys-tems. From this analysis characteristic para-meters can be obtained for the OFDM sys-tem designer, such as the maximum PAPRand the “effective” PAPR, which is defined asthe PAPR at which the probability of errorscan be considered negligible in practice. Theimpact of the clipping rate on the perfor-mance was considered in [3], which gives in-sight into the nature of clipping in terms ofthe level-crossing statistics of OFDM signals.Using the approach in [1, 2], new codes withlow PAPR were recently designed that showbetter performance than the commonschemes and suggest interesting conclusionsabout the triple code rate, minimum dis-tance and PAPRs for codes.

Another disadvantage is the impact of themobile channel, which forces the system to

adapt to the channel. Taking into accountthat future wireless systems are expected tooperate in highly mobile environments, thetime needed for channel estimation for MIMOsystems can become a significant part of thecommunication time, and the system perfor-mance will strongly depend on the quality ofthe estimation schemes. It was shown that avery efficient pilot-based estimation schemecan be devised that depends on the numberof subcarriers, representing the degrees offreedom in the system, the number of trans-mitter antennas and the channel delay pro-files. This scheme also has low PAPR. Thefundamental limits of this scheme in terms ofthe pilot signals were also investigated andoutlined.

This work was supported by the Ministryfor Education, Science, Research and Tech-nology of the Federal Republic of Germanyunder Grant No. 01BU150.

[1] G. Wunder and H. Boche, “Peak valueestimation of band-limited signals from theirsamples, noise enhancement and a localcharacterisation in the neighborhood of anextremum”, IEEE Trans. on Signal Processing,2003.

[2] G. Wunder and H. Boche, “New resultson the statistical distribution of the crest-fac-tor in OFDM”, IEEE Trans. on InformationTheory, 2003.

[3] G. Wunder and H. Boche, “Evaluatingthe SER in OFDM transmission with nonlin-ear distortion: An analytic approach”, 7th Int.OFDM-Workshop 2002, Hamburg, Sept.2002.

Gerhard Wunder (wunder@hhi.de)

MIMO with OFDM for Future 4G Wireless Systems

Orthogonal frequency division multiplexing (OFDM) in combination with multiple anten-nas (MIMO) is a possible communication technique for existing as well as future 4G wire-less systems. In this work we investigate the peak-to-average power ratio (PAPR) of thetransmitted signals, the achievable channel capacity, channel estimation schemes, andspace-frequency codes. The PAPR problem is still the major obstacle to implementingOFDM in low-cost applications.

80

In multipath channels, conventional multi-carrier (MC) transmission using subcarriersbenefits from the lower time dispersion persubcarrier, which is due to the larger symbollengths. This leads to reduced intersymbolinterference, compared to a single carriersystem operating at the same data rate. Ob-viously this choice of the carriers matches thetime-invariant channel. The most popular MCsetup for this situation, orthogonal frequen-cy-division multiplexing (OFDM), has alreadybeen implemented in several standards suchas DAB and DVB-T.

Extending this concept to the time-varyingchannel leads to the question of how to findthe optimal carrier pulse shapes to minimizethe intercarrier and intersymbol crosstalk.The mean time-frequency power profile ofthe channel gives rise to a partition of thetime-frequency plane into uncorrelated re-gions. It is intuitively clear that the optimalcarriers have to match this time-frequencyprofile. Such adaptation to the channel re-quires control over the transmitter and re-ceiver pulse parameters, especially their lo-calization, which is not possible with theconventional OFDM scheme. Having this pic-ture in mind, and additionally motivated bythe reduced spectral efficiency of OFDM dueto the cyclic prefix, several authors have pro-posed new MC transmission techniques,mostly based on DFT filterbanks.

In [1] we established a generalized formu-lation of linear multicarrier transmissionschemes. Using this concept we found a de-scription of the most basic time-variant dis-tortion, the frequency offset. This work cov-ers the framework of biorthogonal frequen-cy-division multiplexing (BFDM) [2] and Band-width Efficient Nonorthogonal MulticarrierTransmission (NOFDM) established in [3].The motivation behind this is to study the ef-fect of carrier frequency mismatching as wellas take the first steps towards exploring time-variant channels. We confirmed the theoreti-cal description of the mean square error andthe interference power caused by the fre-quency offset with simulations, and studiedtheir impact on the symbol error rate.

Further we showed that careful pulse shap-ing, as in the figure, significantly improvesthe performance of the BFDM/NOFDM ap-proaches.

Finally, the resulting multicarrier designprocedure results in a robust transmitter andreceiver setup for given requirements ofspectral efficiency and constraints on pulseshapes.

This work was supported by the FederalMinistry of Education and Research undergrant 01 BU150.

[1] P. Jung, G. Wunder and H. Boche,“Comparisons of standard OFDM/BFDM tobandwidth-efficient pulse shape optimizedMC schemes”, International OFDM Workshop2002, Hamburg.

[2] W. Kozek, “Northogonal pulseshapesfor multicarrier communications in doublydispersive channels”, IEEE Journal on Se-lected Areas in Communications, vol. 16,no. 8, pp. 1579-1589, October 1998.

[3] T. Hunziker and D. Dahlhaus, “Iterativesymbol detection for bandwidth efficientnonorthogonal multicarrier transmission”,Trans. on Communications, to be publishedin 2003.

Peter Jung (jung@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Bandwidth-Efficient Non-Orthogonal Multicarrier Transmission Schemes

Multicarrier transmission schemes are promising candidates for next generation broad-band wireless communication systems. A number of new techniques were recently pro-posed to increase the spectral efficiency and adaptivity in time-variant channels. In thiswork we characterize these systems in terms of several system performance parameters.

Pulses with good andsymmetric TF localisation

before and after pulse shaping

81H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

It is now well known that multiple-elementantenna arrays can improve the performanceof a wireless communication system in a fad-ing environment. The single-cell multiuserscenario, in which each mobile is equippedwith a number of transmit antennas and thebase station has many receive antennas, iscalled the multiple-input multiple-output(MIMO) multiple-access channel (MAC).

The analysis of the theoretical limit of theinformation that can be successfully trans-mitted from the users to the base station is adifficult problem due to the large number offree parameters in the transmitter covariancematrices at the transmit antenna arrays. Onemain performance parameter of interest isthe sum capacity of the MIMO MAC.

In [2] we optimize the sum capacity of theMIMO MAC under the sum power constraintby first separating the optimization probleminto two coupled optimization problems: thecovariance matrix optimization and the pow-er allocation problems. The covariance ma-trix optimization problem for fixed power al-location was solved in [1]. The iterative wa-terfilling algorithm yields the optimumtransmit covariance matrices for a given sig-nal-to-noise ratio (SNR) and power alloca-tion. The power optimization problem forfixed covariance matrices can be solved byinterior point methods because the sum ca-pacity is a concave function of the power al-location.

By alternating between the covariance ma-trix optimization and power allocation prob-lems, we obtain an iterative solution for theoptimum transmit covariance matrices thatsolves the sum capacity optimization prob-lem. In [2] we simplify this approach to ob-tain a less complex algorithm that leads tothe same optimum solution. Both algorithmshave the property that the sum capacity isincreased at every iteration step. The algo-

rithms are stopped when the power opti-mization step leads to the same power allo-cation as in the previous iteration.

The Sato bound offers an alternative ap-proach for finding the sum capacity point ofthe MIMO MAC. The Sato bound is the ca-pacity of the cooperative system with worstcase noise. It gives an upper bound of thecapacity region of the MIMO MAC. At thesum capacity point the Sato bound is tan-gential to the capacity region. In [2] we de-velop an algorithm that iteratively computesthe sum capacity. First we compute thetransmission strategy that maximizes the ca-pacity, and then the noise covariance matrixthat minimizes the capacity. This can bemodelled as a two player game in which oneplayer wants to transmit as much informa-tion as possible while the other player choos-es the noise that most disturbs the transmis-sion. This min-max problem leads to a saddlepoint that corresponds to the sum-capacitypoint of the MIMO MAC. We characterizethis saddle point and develop an algorithmthat can find it for a given SNR and a givenchannel realization.

Future work includes the fairness issues inMIMO MAC transmission scenarios. Each userhas their rate requirement depending on theservice they are using. The satisfaction of raterequirements is still an open research prob-lem.

This work was supported by the FederalMinistry of Education and Research undergrant 01 BU 150.

[1] Wei, Y., Wonjong Rhee, S. B., and Cioffi,J. M., “Iterative water-filling for gaussian vec-tor multiple-access channels”, submitted toIEEE Transactions on Inf. Theory, 2002.

[2] H. Boche and E. Jorswieck, “Sum ca-pacity optimization of the MIMO GaussianMAC”, Proc. WPMC 2002.

Eduard Jorswieck (jorswieck@hhi.de)

Sum-Capacity Optimization of the MIMO Gaussian Multiple-AccessChannel

We study the sum capacity of a Gaussian multiple-input multiple-output multiple-accesschannel with a sum power constraint. In order to develop an efficient algorithm for maxi-mizing the sum capacity, we extend recent results about the duality between the vectormultiple access broadcast channel and the Sato bound. We extend the iterative water-fill-ing algorithm from [1] to obtain the optimum power allocation.

82

The spectral efficiency of interference-limit-ed cellular wireless systems can be signifi-cantly increased by using multiple antennasfor each communication link. By spreadingthe signals over the antennas we can exploitthe spatial diversity and multiplexing gain of-fered by the multipath propagation channel.The spatial domain can be viewed as an ad-ditional resource to the classical resources,bandwidth and power.

The potential capacity gains come at thecost of increased hardware infrastructure, de-pending on the number of additional anten-nas. Since the mobile stations (MS) are typi-cally small low cost hand-held devices, it isdesirable that all complexity resides at thebase station (BS). Thus, beamforming withmultiple BS antennas and a single MS anten-na has recently attracted significant interestand is considered a key technology for fourthgeneration cellular systems.

Despite significant work done in the areaof beamforming, the development of multi-user beamforming in conjunction with thenetwork-level techniques of power controland resource allocation is still not well under-stood. In particular, the downlink from theBS to the mobile terminals is difficult to han-dle analytically. This is because all downlinkchannels are intertwined by mutual crosstalk,which depends on all transmission powersand beamformers, in contrast to the uplinkchannels, which are only coupled by theirpower levels. There is a close relation be-tween the downlink beamforming problemand the problem of finding an achievable re-gion for the non-degraded broadcast chan-nel, which is a longstanding and unsolvedproblem in network information theory.

In [1] the HHI has found a duality betweenuplink and downlink multiuser channels. Inparticular, it was shown that under certainconditions the same signal-to-interference-plus-noise ratios (SINR) are achievable inboth links, assuming that the same sumpower constraint is imposed. Moreover,these levels can be achieved by using thesame beamforming solution. This dualityholds if either all users have the same receiv-

er noise level or if the channel has the specif-ic structure given in [1].

There is an immediate and useful conse-quence of this duality result: a solution of thecomplicated downlink problem can be foundby solving the easier-to-handle uplink prob-lem instead. This opens up a way of design-ing efficient algorithms. This was demon-strated in [2], where a computationally effi-cient algorithm was developed that controlsSINR levels according to individual targetthresholds by using a nonlinear beamform-ing strategy with decision feedback, alsoknown as “dirty paper” pre-coding. This stra-tegy decomposes the channel into a series ofsub-channels, each interfering only with sub-sequent sub-channels. This strategy is opti-mal in that it achieves the given SINR targetthresholds with minimum total transmissionpower.

Another application of the duality resultwas presented in [1], where a transmissionstrategy was proposed that maximizes thetotal throughput of the downlink multiuserchannel for a given sum power constraint.The global optimum is such that only theusers with “good” channel states are allowedto transmit at any given time. Such a strate-gy is advantageous for applications such asdelay-insensitive packet-switched traffic.

This work was supported in part by theFederal Ministry of Education and Research(BMBF) under grant 01BU150.

[1] H. Boche and M. Schubert, “A generalduality theory for uplink and downlink beam-forming”, IEEE Vehicular Techn. Conf. (VTC),Vancouver (CA), Sept. 2002.

[2] M. Schubert and H. Boche, “Joint ‘dirtypaper’ pre-coding and downlink beamform-ing”, Proc. IEEE Internat. Symp. on SpreadSpectrum Techniques and Applications (ISSS-TA), Prague (CZ), vol. 2, pp. 536-540, Sept.2002.

Martin Schubert (schubert@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Duality Between Multiuser Beamforming Transmission in the Uplink andDownlink

Downlink multiuser beamforming is more complicated than the corresponding uplinkproblem because of the special crosstalk structure of the downlink. We show that bothchannels are closely linked by a duality relation. This leads to efficient algorithmic solu-tions, which can be found by focussing on the easier-to-handle uplink.

83H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

If the radio channel is known at the basestation (BS), the data can be preprocessedprior to transmission. The data stream istransformed serial-to-parallel, appropriatelypreprocessed and sent simultaneously withnT transmit antennas over the radio channelH. The MR mobile terminals receive the sig-nal y = H · x + n = d + n after preprocessing.This corresponds to parallel transmission chan-nels with additive Gausssian noise (AWGN).

Reference [1] proposed a fully decorrelat-ing scheme based on spatial nulling. Thepreprocessing is done with the Moore-Penrose pseudo inverse of H, but this JointTransmission (JT) method requires hightransmitter power if the channel is not wellconditioned.

A more sophisticated concept which alsoachieves full receiver signal decorrelation isTomlinson-Harashima Precoding (THP) [2].Here known interference is eliminated at thetransmitter by sending the original signal,but with the known interference subtracted.This technique can save transmit powercompared to JT because fewer spatial nullshave to be set.

A new proposal, Joint Costa Beamforming(JCBF) [3], is an optimal downlink beam-forming strategy that minimises the trans-mission power while satisfying individual sig-nal-to-noise-plus-interference-ratio require-ments at the mobile terminals.

Figure 2 shows the average power en-hancement factor (PEF) compared to parallelAWGN transmission for the investigatedschemes. Compared to JT, the nonlinearschemes THP and JCBF save significantamounts of transmitter power. Rural area

scenarios with only a few paths and withsome users either close to or very far fromthe BS, for which the matrix H may be ill-conditioned, clearly benefit from the JCBFscheme. The drastic reduction of transmitpower is due to the optimal trade-off be-tween decorrelation and noise enhancement.For SINR —› ∞ the THP and JCBF solutionsconverge asymptotically.

This work was supported by the FederalMinistry of Education and Research undergrant 01 BN 150.

[1] P.W. Baier et al., “Joint transmission, analternative rationale for the downlink of timedivision CDMA using multi-element transmitantennas”, IEEE ISSSTA, NJIT, USA, 2000.

[2] R. Fischer et al., “MIMO precoding forDecentralized Receivers”, ISIT, Lausanne (CH),2002.

[3] M. Schubert and H. Boche, “Joint ‚DirtyPaper’ Precoding and Downlink Beamform-ing”, IEEE ISSSTA, Prague (CZ), 2002.

Thomas Haustein (haustein@hhi.de)

On Power Reduction Strategies for the Multiuser Downlink withDecentralized Receivers

Multiuser transmission systems using multiple antenna arrays at the base station may in-crease the transmission capacity, or reduce the sum transmit power, significantly. Thepower reductions with three different downlink transmission schemes is investigated inthis work.

Fig. 1:

Block diagram for data

preprocessing at the BS

with channel knowledge

Fig. 2:

Power enhancement

factors (PEF) for JT, THP

and JCBF

(top: Rayleigh channel;

bottom: rural area).

Note the different dB

scales.

84

In recent years, the goal of providing highspeed wireless data services has generated agreat amount of interest among the researchcommunity. Recent information-theoretic re-sults have demonstrated that the capacity ofthe system in the presence of Rayleigh fadingimproves significantly if multiple transmitand receive antennas are used.

We considered in [2] a wireless Multiple-Input Multiple-Output (MIMO) system withN transmit and M receive antennas. It wasassumed that the channel is a flat-fadingRayleigh channel. For this system, the authorsin [1] proposed a low-complexity space-timescheme called Wrapped Space-Time Coding(WSTC) to achieve high spectral efficiencies.This scheme works as follows. After encodingthe binary sequence with a convolutionalcode, the bit sequence is then modulatedand interleaved using a diagonal interleaver.The data are then transmitted over the Ntransmit antennas. Decoding at the receiveris done by processing according to the inter-leaver structure. Nulling and cancellation aredone using per-survivor-processing, whichvery effectively reduces the effect of errorpropagation.

In [1] it was assumed that the channel isperfectly known at the receiver. However, inpractice it is undesirable to spend too muchtime estimating the channel coefficients be-cause this would reduce the spectral efficien-cy (i.e. long training sequences are not al-lowed, as it may be impractical to estimatethem within an acceptable delay constraint).Also, the assumption of perfect knowledge ofthe channel state information (CSI) may notbe realistic with a large number of transmitantennas. Therefore we analyzed in [2] theimpact of imperfect CSI on the decision met-ric of the Viterbi algorithm (VA) and on theperformance of this scheme.

We also developed a novel receiverscheme that uses pilot symbols to estimatethe channel coefficients and couples thiswith an iterative process that uses the decod-

ed information to improve the initial esti-mates. In order not to reduce the spectral ef-ficiency of the system too much, we used aminimal number of pilot symbols for the ini-tial channel estimation. In addition to this,we compared our scheme with otherschemes. It was shown through simulationsthat the absolute channel estimation error athigh signal-to–noise ratios (SNRs) for ourscheme is equal to that of a system in whichonly pilot signals are transmitted. At lowSNRs the performance of the channel estima-tion scheme is not further improved by theiterative decoding and channel estimationprocess. We also showed in [2] that ourscheme performs better than other schemeswith higher complexity. In conclusion, theWSTC in [1] gives good performance at lowcomplexity. However, the performance strong-ly depends on the accuracy of channel stateinformation at the receiver. Our new receiverscheme reduces the effect of channel estima-tion errors on the frame error rate throughjoint decoding and channel estimation.

This work was supported in part by theGerman Ministry of Education and Research(BMBF) under grant 01BU150.

[1] G. Caire and G. Colavolpe, “On space-time coding for quasi-static multiple-antennachannels”, Globecom 2001, San Antonio(USA, TX), November 25-29, 2001.

[2] A. Sezgin and E.A. Jorswieck, “Joint de-coding and channel estimation for low-com-plexity STC”, ASILOMAR 2002, Pacific Grove(CA, USA), 3-6 November 2002.

Aydin Sezgin (sezgin@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Joint Decoding and Channel-Estimation for Low-Complexity Space-TimeCoding

In this work we study a low-complexity space-time architecture [1] employing per-sur-vivor-processing with imperfect channel state information (CSI) at the receiver. Weanalyse the impact of imperfect CSI on the decision metric of the Viterbi Algorithm andon the performance of the architecture. To achieve large spectral efficiency we use only aminimum number of pilot signals for the initial channel estimation. The novel receiverscheme decodes the symbols stepwise and improves the initial channel estimation. Wecompare our scheme in numerical simulations with other schemes in terms of perfor-mance and complexity.

85H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

Future radio systems will make use of co-operative concepts between independenttransmitters and receivers to increase thecoverage area and data rate and/or to de-crease the power consumption of the wire-less communication network.

Figure 1 shows the underlying model ofthe distributed multiantenna system underconsideration.

A station wishing to transmit, depicted bythe information source S, divides its informa-tion into t independent signals xi of equalpower and distributes them through an un-specified distribution network to the cooper-ating stations CS. Each signal is disturbed byan additive white Gaussian noise ni, also as-sumed of equal power. Each cooperating sta-tion amplifies its disturbed signal by the fac-tor βi and transmits the amplified signal si tothe access point AP, at which the signalsfrom each of r antenna elements are furtherdisturbed by additive white Gaussian noisesof equal power. This model may for examplerepresent a situation in a WLAN in which astation wishing to transmit data does nothave an adequate link to an access point.

In [1] we calculate the system capacity.Obviously the capacity depends on the cho-sen amplification factors of the cooperatingstations, which also determine the corre-sponding transmission powers. It is shownthat the capacity converges to a limit, deter-mined by the noise of the distribution net-work, as the power of the cooperating sta-tions increases.

There is great interest in finding the opti-mal amplification factors that maximize thesystem capacity, constrained by the maxi-mum total transmission power of all cooper-ating transmitters. This leads to a non-con-vex optimization problem with affine in-

equality constraints. A closed form solutioncan be derived in the case t = 2 [1]. In othercases it can be solved by a numerical algo-rithm. The results give deeper insights intocooperative transmitter systems.

The optimal number of cooperating sta-tions depends on the total transmission pow-er. Accordingly, the optimal power allocationbetween the cooperative stations may belikened to the waterfilling strategy in MIMOsystems, although no unitary preprocessingtakes place.

This result is of practical importance, sinceit gives the optimum number of stations toallocate for a given total transmission powerin a particular scenario. Hence it suggests de-sign constraints for the unspecified distribu-tion network.

[1] T. J. Oechtering and H. Boche, “On thecapacity of a distributed multiantenna sys-tem using cooperative transmitters”, accept-ed at VTC 2003 (Spring).

Tobias J. Oechtering(tobias.oechtering@tu-berlin.de)

On a Distributed Multiantenna System using Cooperating Transmitters

We examine a system in which a station desiring transmission cooperates with otherreachable stations in its vicinity to achieve a performance gain from the resulting distrib-uted multiple antenna link. Here we consider the cooperative concept of amplify and for-ward, in which the cooperating stations amplify and retransmit the received signal. Anexample of an optimal power allocation strategy for improved capacity is presented.

Fig. 1:

System model

Fig. 2: Example of an optimalpower allocation of asystem with t = r = 3and arbitrary channel realisation

86

The decision to use CDMA as a multipleaccess scheme for UMTS (Universal MobileTelecommunications System) was made be-cause of its enormous potential for largespectral efficiency. CDMA can achieve spec-tral efficiency improvements by incorporat-ing a number of features. Chief among theseare frequency reuse, soft capacity, soft han-dover and mitigation of the effects of fadedtransmission through the use of a RAKE re-ceiver.

As UMTS is being implemented, it is be-coming obvious that W-CDMA may not fulfilall its expectations. For instance, it is difficultto satisfy stringent quality of service require-ments with regard to data rate and loss. Thisis especially true in the uplink channel, inwhich random signature sequences are usedfor the channelization of users. The use ofrandom sequences results in strong multipleaccess interference, making reliable, high da-ta rate communications impossible. The mainreason for such an approach is that sequencedesign for fully asynchronous CDMA systemsis a notoriously difficult problem, and no sys-tematic methods are available. The situationis further complicated by the fact that vari-able spreading factors are employed to sup-port variable data rates.

In QS-CDMA, users are approximately syn-chronized, in the sense that the maximal sig-nal delay (relative to a common clock) is sig-nificantly smaller than the duration of thesignature waveforms. Furthermore, all signa-ture sequences used in QS-CDMA have thesame length, and variable data rates are sup-ported through the use of multicode spread-ing techniques. In many practical situationscoarse synchronization is either already givenor can easily be established [1]. This fact canbe used to improve the system performance,provided that the aperiodic correlations ofthe signature sequences are optimized in acertain window around the zero shift, the so-called interference window.

In [2] we proposed criteria for selectingsignature sequences for QS-CDMA systemsand derived lower bounds on them. Thebounds suggest an enormous potential forperformance gain. We presented two meth-

ods for the construction and allocation ofsignature sequences. In some cases the cor-relation parameters of these sequences areclose to the optimum, showing that the de-sign of good sequence sets for QS-CDMA is afeasible problem.

The figure depicts the average bit errorrate as a function of the signal-to-interfer-ence ratio in a multipath QS-CDMA system.We compared new sequences with the well-known Kasami sequences, which are optimalwith respect to the maximum periodic corre-lation value. The simulation indicates that wecan improve the performance by as much as4 dB at a bit error rate of 10-4.

[1] S. Stanczak and H. Boche, “A potentialair interface for 4G wireless communica-tions”, Proc. ITCOM 2002, Boston,Massachusetts, USA, July 29-August 2, 2002.

[2] S. Stanczak and H. Holger, “On se-quence sets for CDMA channels with a smalldelay spread”, 36th Asilomar Conference onSignals, Systems and Computers, Monterey,CA, USA, November 3-6, 2002.

Slawomir Stanczak (stanczak@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · M O B I L E B R O A D B A N D …

QS-CDMA versus W-CMDA: A Comparison of Air Interfaces for WirelessCommunications

Sequence design for W-CDMA (wideband code-division multiple access) is difficult, mak-ing the use of scrambling codes necessary, which drastically decreases the channel capaci-ty. In contrast, good sequences for quasi-synchronous CDMA (QS-CDMA) systems areknown and can be used to enhance the system performance.

Average bit error rate in

a multipath QS-CDMA

channel with 8 users and

with processing gain 63.

87H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

MPEG-7 offers a wide range of possible de-scriptions of video content that allow directaccess to individual video files or video seg-ments, as well as links to related material ofany kind. From a user’s perspective, not all ofthem are relevant for all purposes or for allvideo content types.

Following the value chain shown in the fig-ure, the users addressed in the BUSMAN pro-ject might be roughly classified as privateusers (consumers) and professional users(production units, broadcast agencies andarchives). The video content chosen aremovies, sports footage material (football),and tourism video material.

BUSMAN adopts a user-centred approach,as suggested in ISO 13407. The video re-trieval requirements of various user groupswere derived from interviews and focusgroups conducted by the BUSMAN consor-tium.

Across the very heterogeneous groups theresults show a strong requirement for query-ing using high level descriptions of the videocontent, such as creation information (e.g.actor, director), classification (e.g. genre) andsemantics (events, objects), rather than lowlevel descriptions such as colour, shapes ortextures.

The main requirement reported from theprofessional group is the demand for fast ac-cess to high quality non-degraded video.Free text search with the possibility of iterat-ing the search is needed. For instance, thelight conditions of shots are of great interest.

These aspects can be covered by applyingrelevance feedback approaches in order tofind similar keyframes.

Since the annotation of video material is atime consuming process, an effective anno-tation tool is required to embed the relevantmetadata. The development of mechanismsthat allow high level descriptions to be in-ferred from low level information is beingconsidered. These should be at least semi-au-tomatic.

Querying and delivery across mobile envi-ronments based on GPRS, UMTS, fast fixednetworks and the Internet is also being con-sidered. Because of the special characteristicsof the various networks and devices, a num-ber of constraints on the input and outputfacilities must be taken into account. In par-ticular, the mobile access to video databasesrequires user interfaces that allow a straight-forward navigation by means of menu struc-tures that meet user's expectations. Thesearch interests reported by private con-sumers seem to allow a hierarchically organ-ised search.

This work is partly funded by the EuropeanCommission under the European Union’sInformation Societies Technology Program-me (IST).

Further information on the BUSMAN pro-ject can be found at http://www.ist-busman.org.

Roland Buß (buss@hhi.de)

User-Friendly Retrieval of Video Content from Large Databases

When designing a system for efficient retrieval of video content from large databases,various factors have to be taken into account, among others the large variety of contentand many different user requirements and reasons for using the system. In the BUSMANproject both of these issues are addressed by embedding relevant and fully MPEG-7 com-pliant metadata into the video content. Based on interviews with potential users, thosedescriptors and description schemes that best fit user expectations and demands for suc-cessful video retrieval were selected and have been implemented into a metadata model.

The value chain, with

the stages addressed by

BUSMAN shown in bold

88

At present, a glasses-free 3D display thatenables free positioning of the viewer is notavailable. Most of the existing 3D displaysimpose fixed viewing positions. Others in-clude a limited form of head tracking to pro-vide a multitude of fixed positions for good3D viewing, but in between these viewingzones an acceptable 3D impression cannotbe generated. HHI is currently developing adisplay that will allow free positioning of asingle viewer within a 60 degree angle. Asecond common artefact of currently avail-able displays is crosstalk between the left andright views. The optics for the new develop-ment will be designed so that extremely lowcrosstalk (< 1 %) and excellent colour repro-duction will be achieved.

For the representation of stereoscopic con-tent, two partial images showing an objector a scene from two slightly different per-spectives must be presented at the sametime. A technology patented by theHeinrich-Hertz-Institut [1] guarantees a cor-rect optical addressing of the user's eyes. Leftand right images are split into vertical stripeswhich are steered on the appropriate eyes bymeans of fine cylindrical lenses. Dependingon the viewer’s displacement, a lens plate istracked in two axes with a precision of about10 µm. A special bearing setup and a drivingdevice using voice coil motors enables theviewer to perform lateral and frontal move-ments while watching excellent stereoscopicvideo images. In addition to low cost, voicecoil motors have other advantages in this ap-plication, including especially noiseless oper-ation, high velocity and accuracy, and man-ageable driving electronics.

The screen of a 21’’ liquid crystal panel issplit into monoscopic and stereoscopic dis-play areas. While 3D images or movies arebeing displayed in one area, the second dis-play area can be used for monoscopic pre-sentations, such as additional program infor-mation for 3D TV or an internet browser forsearching 3D content.

The detailed technical design of the track-ing 3D display is shown in the figure. A ro-bust camera-based head detection devicewas developed to sense the head positionwithout any user-worn devices such as glass-es. An optional infrared light source ensures

optimal eye detection even if the existing vis-ible illumination is insufficient. The patternsof the captured images are analysed via aPC-based frame grabber system to detect theeyes of the observer. The processed head lo-cation data are sent to a processing unitwhich supplies a pulse-width modulated da-ta stream for driving several voice coil motors– one for the lateral axis and four for thefrontal axis. The required performance andprecision of the real-time spatial positioningof the lens plate is achieved using a custom-made PID control system.

Human factors studies at all stages of thedevelopment will determine the user require-ments for optimal 3D visual enjoyment.They will also provide tools for quality con-trol during the development.

This work is supported by the InformationSociety Technologies Programme (IST) underthe Fifth European Community FrameworkProgramme.

[1] R. Börner, “Autostereoscopic viewingdevice for creating three-dimensional per-ception of images”, Patent applicationsEP 0 404 289 B1, US 5,083,1999, andP 2.874.966.

Klaus Hopf (hopf@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

User-Tracking 3D Display for 3D TV and Internet Browsing

The availability of 3D displays is essential for the introduction of 3D TV and PC-based sys-tems implementing augmented reality. This article describes a new type of tracked single-user display suitable for 3D TV and internet browsing.

Technical design

of the 3D display

89H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

The retrieval of digital images based onimage features rather than text descriptionshas been the subject of considerable researchefforts in recent years.

Feature vectors describing visual propertiessuch as colour, texture and edge statistics arecomputed for the whole image. Images areconsidered to be similar if the Euclidean dis-tance between their feature vectors is small.Figure 1 shows the result of such a search re-quest.

Retrieval is fast with this method, but theretrieval results are not satisfactory – theremay be retrieved images with no similarity tothe query image.

The typical user searches for images show-ing semantic objects such as cars, houses orpersons. These semantic objects cannot bedescribed by feature vectors calculated fromthe whole image. An adequate descriptionneeds both a suitable representation of thevisual properties of the individual image seg-ments and their positions relative to eachother.

In our research a new graph-based similari-ty measure for comparing whole images andparts of segmented images has been devel-oped. It takes account of the colour, edgeand textural properties of image segments aswell as their relative positions. Hence theuser can search for semantic objects.

The transformation of an image into a la-belled graph requires two steps. Image seg-mentation and the extraction of MPEG-7 de-scriptors, which describe the visual proper-ties, take place in the first step. In the secondstep the images are represented by labelledgraphs. The set of all centroids is the set ofnodes. Every node is labelled with an MPEG-7feature vector. Edges are introduced be-tween each pair of nodes. The edges are la-

belled with the distances between the cen-troids, normalized with respect to the imagediagonal.

Images are considered to be similar if thedistance between their representations by aconfiguration of features is small. Due to thegraph representation used here it is neces-sary to compute a graph distance. Mostgraph distances need a unique node assign-ment. But there is still no system that is ableto automatically segment images into se-mantically meaningful parts. Furthermorethe segmentation results depend strongly onthe illumination condition, camera positionand algorithm parameters. Different graphrepresentations of one and the same imageare possible.

In order to compare two images, bothgraphs are first normalized. This is necessaryto handle the segmentation dependency.We formulated the graph normalizationproblem as an optimization problem andsolved it using a connectionistic method. Thenormalized graphs are then used as the basisof a fast recognition procedure, using a spe-cial neural net to compute the graph dis-tance. This graph metric is described in theHHI Report 2001. For more details see [1]and [2].

[1] S. Bischoff and F. Wysotzki, “Graphbased representation of objects in image re-trieval”, Proc. 5th International Workshop onInternet Technology and Applications, KluwerAcademic Publishers, 2002.

[2] S. Bischoff and F. Wysotzki, “A new dis-tance measure for segmented images basedon MPEG-7 descriptors”, Tech. Report 2019,TU Berlin, Germany, 2002.

Stefan Bischoff (bischoff@hhi.de)

A New Similarity Measure for Segmented Images

A new similarity measure for segmented images was developed. This measure takes ac-count of the colour, edge, texture and shape properties of image segments as well astheir relative positions.

Fig. 1:

Result of a classical

search request. The

complete first image is

the query image.

Fig. 2:

Result of a search

request using our

approach. The framedimage part is the queryimage, and the underly-

ing labelled graph is the

query graph.

90

Many communities and offices of citizenservices are presently trying to improve therelationships between administrations andcitizens. One step in that direction is to orga-nize offices of citizen services – which aremainly located in town halls or similar build-ings – as one-stop offices in which citizenscan be advised and can use services from awide range of different public administra-tions.

As a second step, some administrationshave started to offer access to some citizenservices over the Internet, e.g. for download-ing forms or even for filling in electronicforms.

However, these innovations do not ade-quately cater for citizens who are, for variousreasons, not able or not willing to use the of-fices of citizen services. For example, for el-derly, ill or disabled citizens it is very oftentoo exhausting to walk or ride to a publicbuilding. Sometimes they can only make useof citizen services by means of a substitute.Similarly, use of the Internet requires suitableequipment and a certain experience in usingsoftware such as Web browsers etc.

In view of this, the project “mobile citizenservices” is researching novel possibilities foroffering citizen services at different andchanging locations by exploiting mobile/wireless networks and terminals. In particu-lar, the project aims to develop and test amobile office of citizen services that can offera wide range of services, including registra-tion, passports, driving licenses, wage taxcards, social benefits, etc.

These mobile offices should support theentire work flow, from consultancy throughapplication and payment to the final deliveryof (hard) documents to the citizen.

They will be present from time to time inresidential homes for the elderly, perhapshospitals, but also in shopping malls or atweekly markets.

Besides being more citizen-friendly, thosemobile (or “nomadic”) offices are expectedto be more efficient, as they do not requiresuch high rental fees and maintenance costsas stationary offices. Especially in large ad-ministrative districts they will offer a newquality of public service by “taking the of-fice/service to the citizen”.

The project consortium consists of the HHIas a research institute, a software company,and two administrative districts of the city ofBerlin as pilot users. HHI is responsible,among other things, for the user require-ments analysis, the data collection and analy-sis during the field trial, and the usability de-sign of services and terminals.

The use of UMTS is envisaged at a laterstate of the project, but at the beginningGPRS and WLANs will be used for wirelessdata transmission.

The project has started by analysing theorganisational, legal, technical, and ergo-nomic requirements, among other things,for a mobile office of citizen services by visit-ing stationary offices and conducting first in-terviews with experts in the field. In addition,a first version of a software system for variouscitizen services was made available on a mo-bile notebook via a WLAN.

This work is supported by the FederalMinistry of Economics and Labour of theFederal Republic of Germany (BMWA) undergrant 01 MD 226.

Lothar Mühlbach (muehlbach@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

Mobile Services for Citizens

One of the potential benefits of mobile e-government is “to take the services to the citi-zens”, instead of expecting citizens to go to the services. The project “mobile citizen ser-vices” aims to offer a broad range of services (passports, wage tax cards, driving licenses,etc.) by means of a mobile one-stop office for citizen services. The office is being devel-oped and tested jointly with a software company. Various local administrations in the cityof Berlin are the pilot users.

Consultancy in an

office of citizen services

91H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

The present study was performed by aconsortium of eight Fraunhofer organisa-tions, namely ESK München, FIT SanktAugustin, HHI Berlin, IGD Rostock, IIS-AErlangen, IMS Dresden, IZM Berlin, VµEBerlin, and the centre of the FraunhoferMicroelelectronics Alliance (VµE).

The objective of the study was to developa framework to help decide what require-ments should be satisfied by innovative man-machine interfaces and what challenges arelikely to arise in future hardware and soft-ware development projects.

The study was motivated particularly bythe fact that existing man-machine interfacesare not adapted to a technological evolutionthat is characterized by the following trends:• The convergence of language, multimedia

data and services.• The expansion of functionality and services

in the areas of information, communica-tion and action possibilities in all life fields.

• The increased support of users by electron-ic assistants and “smart objects”.

• The availability of the entire spectrum of functionality and services at every time and at every place (ubiquitous computing).

The state of science and technology in thefields of microelectronics, software engineer-ing and usability of services and terminalswas surveyed and analysed in the study.

The task of the HHI was to identify chal-lenges and solutions for usability problemsthat result from:• The transition from stationary internet

applications to mobile applications.• The miniaturisation of input and output

facilities.• Reduced bandwidth when using mobile

devices.

The outcomes of the study were presentedduring a workshop in October 2002 and aredescribed in the final internal FhG report inDecember 2002. To illustrate the type of re-sults obtained two examples are given:

(1) To solve the problem that results fromthe miniaturisation of mobile devices, it isproposed to develop virtual image displaysthat deliver a range of vision similar to thatof the usual PC monitors.

(2) A severe usability problem arises be-cause of inconsistencies between mobile userinterfaces that were developed for differentcontexts and different applications. An ap-proach to cope with this problem is pro-posed.

This work was supported by theFraunhofer Gesellschaft (FhG) München.

Jens Faber (faber@hhi.de)

Innovative Man-Machine Interfaces

Starting from technological trends in the field of information and communication tech-nology, a study was done to help find the requirements for innovative man-machine in-terfaces and to predict the challenges to be met in future hardware and software devel-opment projects.

Technological trends

that require new

man-machine interfaces

92

Human stereoscopic vision is limited to acentral binocular region where the visual fieldsof the left and right eye overlap. The binocu-lar field extends about 114 degrees. It isflanked by two monocular sectors withinwhich objects are visible to only one eye. Inthe lateral sectors, spatial vision relies onmonocular depth cues such as shading, per-spective and occlusion.

From this fundamental concept of humanvision, we have derived the idea of theHybrid Display. With the Hybrid Display the3D presentation is confined to the centralpart of a wide-screen display, while the areasurrounding the 3D image reproduces onlymonocular depth cues. Since the entire dis-play area belongs to a joint data space, it ispossible to make the 3D imagery mergeseamlessly into the surrounding 2D region.

We have implemented this concept in afully operational prototype. Unlike conven-tional 3D techniques, the central 3D displaycreates a stereo image pair focused on anaerial image plane floating 20 cm in front ofthe display [1]. Stereo glasses are not re-quired. The prototype display provides asymmetrical 3D stereo resolution of2 x 1024 x 768 RGB pixels, and each of the2D panels immediately adjacent to the 3Darea adds 1280 x 1024 pixels to the usablescreen space.

The novel display is very comfortable touse (no eye-strain), since it allows accommo-dation (focal adjustment of the eye lens) tothe virtual object’s stereoscopic distance. Bycontrast, conventional 3D displays are knownto produce conflicting accommodation stim-uli when users try to directly touch 3D ob-jects appearing stereoscopically in front ofthe display [2].

The floating image produced by the 3Ddisplay looks like a hologram (very high con-trast and brightness, no crosstalk, high reso-lution) hovering over the desk. The user maytouch it like a real object. Hand gestures arerecognized remotely by a video-based stereohand tracker embedded in the desk in frontof the display. Optionally, tactile feedbackwhen touching a virtual object is provided

by a force-feedback device. Within the 3Darea there is perfect correspondence be-tween the visual and tactile spaces.

Natural interactions with virtual objects be-come possible with this display. With a sim-ple hand gesture, the user can pull a com-puter-generated object out of the 2D areaand move it into the 3D area (drag anddrop), where it will float like a holographicimage within reach over the desk. Since theaccommodation distance of the virtual ob-ject equals the distance of the real thing usedfor manipulation (hand or end effector of aforce-feedback device), there is no accom-modation conflict. Hence this display is ideal-ly suited for mixed reality interaction, for ex-ample, in construction applications, medicalapplications (diagnosis, surgery planning)and chemical applications (molecular design).

This work was supported by the FederalMinistry of Education and Research undergrant 01 BD 250.

[1] S. Pastoor and J. Liu, “3-D display andinteraction technologies for desktop comput-ing”, in: B. Javidi, F. Okano (eds.), Three-Di-mensional Television, Video, and DisplayTechnologies, Springer Verlag Berlin, 2002,pp. 315-356.

[2] S. Pastoor, “3D-Displays: Methodenund Stand der Technik”, Handbuch der Tele-kommunikation, vol. 4, 12.2.1.0, 89, Deut-scher Wirtschaftsdienst Köln, 2002, pp. 1-51.

Siegmund Pastoor (pastoor@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

Hybrid Display – Towards Natural Interaction in Mixed Reality

The Hybrid Display embeds a unique autostereoscopic 3D display into a surrounding 2Ddisplay area. With a simple hand gesture, the user may drag a virtual object from the 2Darea and drop it into the 3D display, where it seamlessly merges into the real desktop en-vironment. In contrast to current stereoscopic techniques, there is no accommodationconflict when the user attempts to touch and manipulate a virtual object floating over thedesktop with the hand or a real tool.

Prototype of the

desktop Hybrid Display

for mixed-reality interaction (as shown at

the CeBIT 2002)

93H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

Mixed Reality Interfaces integrate dynami-cally generated 3D objects into a physical 3Dspace in real time. They can be used to navi-gate, manage and visualise information re-sources and to control tasks. Accurate regis-tration between real and virtual objects iscrucial for MRI because the objects in the re-al and virtual worlds must be properlyaligned to avoid unnatural perceptual arte-facts. Although registration based on mag-netic and ultrasonic sensors has been report-ed, optical tracking has advantages. It usesthe very same image for the registration asthe image on which the synthetic objects willbe superimposed and it doesn’t suffer fromworkspace limitations.

Techniques supporting inside-out opticaltracking (tracking the pose of the camera)based on natural features are exploited andimplemented in a prototype system that wasdeveloped for the purpose of demonstration,case study, and user evaluation in the project“Mixed3D”. To keep the hardware require-ments low (bearing in mind applications inmobile platforms), the current version of theMRI prototype is based on a monocularvideo system that avoids synchronizationproblems between different cameras. It is im-plemented as a coder/encoder structure toprovide, as far as possible, application inde-pendency and flexibility.

The coder part consists mainly of the regis-tration framework that computes the pose ofthe camera as the PDA moves. This frame-work is based on a coarse-to-fine model-based approach. In the initialization stage,having a model of the object, a video imageis analyzed and features belonging to a planeare extracted. The plane projective transfor-mation (homography) is computed and de-composed to provide a first estimate of thethree dimensional position and orientation ofthe object. In the tracking stage the currentpose estimate is used to initialize an iterativepose estimation process based on the Gauss-Newton algorithm. This is computationallyvery efficient, and also allows the recovery ofinternal degrees of freedom (e.g. an objectwith a rotational part) and the tracking of fo-cal length variations (e.g. lenses with auto-zoom features).

A visualization framework based onDirectX is the core of the encoder. It takescare of object generation, rendering andshadowing of the virtual objects. For the dy-namic object generation a model of the ob-ject and a virtual camera are used. The virtu-al camera has the same optical properties asthe physical one and it is used to project themodel according to the pose provided bythe coder. The synthesized image is then su-perimposed onto the live video image.

At present the MRI runs at 20 Hz on aPentium IV system at half PAL resolution. Thegoal in the future is to integrate the MRI intoa 3D PDA and to extend the existing proto-type so that it is robust to outliers, handlesobject occlusion, and merges different kindsof features and various pose recovery strate-gies.

This work is supported by the FederalMinistry of Education and Research undergrant 01 BD 250.

Christos Conomis (conomis@hhi.de)

Inside-Out Optical Tracking for Mixed-Reality PDAs

Mixed reality interfaces (MRIs) overlay three-dimensional graphical objects on live videoand allow interactions between real and virtual objects. The use of optical methods totrack natural features in real time enhances the use of MRI in mobile platforms such asPDAs and Tablet PCs, thus opening a whole new raft of applications in real environments.

Fig. 1: View of the dynamicallygenerated object super-imposed onto the livevideo image

Fig. 2:

View of the mobile MRI

prototype

94

Computers are increasingly used outsidethe office, for example in car repair work-shops, chemical laboratories and productionplants. Typically, in such environments theuser’s hands are not free for interaction orthere is simply too much dirt for using stan-dard input devices such as keyboards, joy-sticks or mice. A remote (video-based) headtracker is perfectly suited for hands-free cur-sor positioning and menu selection in suchapplications.

A video head tracker can also be used tocontrol other devices, such as the vantagepoint of a camera in surveillance and inspec-tion tasks and the orientation of a display.When used with a 3D display, a head trackercan couple the rendered view to the user’shead movement (dynamic perspective),thereby providing a very natural look-aroundeffect. In addition, most of the emerging au-tostereoscopic 3D displays (i.e. 3D withoutstereo glasses) require a remote head track-ing device to optically address the observer’seyes.

In our earlier approaches to video-basedhead tracking we used high-end capturingdevices (precision miniature cameras and PCIframe grabber boards) in order to achievemaximal robustness, precision and adaptabil-ity as well as minimal measurement latencies[1]. The hardware costs were accordinglyhigh (typically about ¤ 1,000).

In order to address an extended applica-tion market, we have completely redesignedour software and modified the basic algo-rithms. The new head tracker accepts a widerange of video cameras and camera inter-faces, including web cams (320 * 240 pixelsat 30 Hz) and special high speed cameras(648 x 247 pixels at 120 Hz). Also, with asoftware redesign we were able to reducethe processor load significantly. The recentsoftware version uses less than 20 % of theCPU power, so that other applications mayrun (and be controlled by the tracker) on thesame PC without delay.

Most computer vision algorithms requirehigh-quality video inputs and full knowledgeand control of the camera parameters. Onthe other hand, with typical low-cost web

cameras the automatic gain control mecha-nism cannot be switched off and the imagequality is far from excellent because of com-pression and lens artefacts. Moreover, cur-rent USB web cams have a substantial laten-cy. Because of the frame-interleaved com-pression, about 160 ms elapses before arecorded image is available to the head-tracker image processing algorithms. Such adelay can only partly be compensated by thepredictor implemented in our software (apredictor is typically very sensitive to noiseinterference). However, first trials show thateven with the existing latencies the trackercan be used to reasonably substitute for amouse and to provide a dynamic perspec-tive.

Projected USB 2.0 and IEEE1394 cameraswork without video compression. This willsignificantly reduce the latency, so that thelow-cost head tracker can then be used indelay-sensitive applications as well.

This work was supported by the FederalMinistry of Education and Research undergrant 01 BD 250.

[1] S. Pastoor and J. Liu, “3-D display andinteraction technologies for desktop comput-ing”, in: B. Javidi, F. Okano (eds.), Three-Dimensional Television, Video, and DisplayTechnologies, Springer Verlag Berlin, 2002,pp. 315-356.

David Przewozny (przewozny@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

Low-Cost Video Head Tracker for PC Applications

So far head tracking devices have been used only for special applications running onhigh-end workstations. This situation has changed with the increasing processing powerof PCs and the availability of inexpensive web cameras. It is now possible to use a headtracker as an input device for any general-purpose PC. “Head mouse” and dynamic per-spective are typical applications for low-cost video head trackers.

Graphic user interface of

the video head tracker,

showing a sample appli-

cation with dynamic

perspective. The web

cam used is easily

mounted on top of amonitor.

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The development of algorithms and for-mats for interactive multiple view video sys-tems has become an important field of R&D.The project OIS targets a traffic surveillancescenario in which a crossing is observed by anumber of cameras (typically four).

The first part of this work is about a systemthat is suitable for video capturing, encod-ing, transmission and display. A remotelyconfigurable video streaming server has beendeveloped, capable of video capturing, for-mat conversion, MPEG-4 encoding and RTPstreaming. The server can be controlled via aspecial TCP interface from a central client, inorder to adjust to varying network (e.g.WLAN) conditions and user requirements.This is done by adjusting format conversionand encoder parameters.

A multi-client is being developed as a con-trol station. It displays the traffic surveillancevideos of the cameras in the network, con-trols the dynamic transmission system (itmeasures network conditions and configuresmultiple servers accordingly), and handlesthe user interaction. For example, it is possi-ble to switch views on and off and to get en-larged views from selected cameras.

The second part of the project targets 3Dscene reconstruction and a system for inter-active navigation within the extracted 3Dmodel. For this purpose the scene is dividedinto static and dynamic parts.

The static parts are handled off-line and in-teractively. This includes calibration of allcameras, background extraction in all viewsand 3D background modelling as multi-tex-tured objects (surface light fields). The tex-

tures are derived from the different cameraviews. The static models can be updated,e.g. if there is a change of lighting.

The dynamic parts of the scene are vehi-cles, pedestrians and others. These are han-dled on-line and automatically, includingsegmentation of all views, multiple viewtracking and 3D reconstruction. The last isdone by selection and adjustment of an ap-propriate 3D model from a data base, withtexture mapping from the original video se-quences.

The modelled static and dynamic scene el-ements are combined in a 3D scene repre-sentation which is realized in DirectX andcan be viewed and navigated interactively.The dynamic traffic scene can be viewedfrom an arbitrary position.

The technology developed in OIS is not re-stricted to the traffic surveillance scenario.The transmission system could also be usedfor other purposes, e.g. for video conferenc-ing with several persons. The 3D scene re-construction system could be used for a vari-ety of similar scenes and camera settings.

These developed and other similar tech-nologies for video based rendering have re-ceived much interest in recent years. Theyhave in common that they support interac-tivity with the content, in that the user canselect his or her own view direction and/orviewpoint in an audio-visual scene (within acertain operating range). Therefore MPEGhas started to investigate the need for stan-dardization in this field in a new initiative,which is called 3DAV. HHI has been very ac-tive in 3DAV from the very beginning andhas contributed many inputs, e.g. for inter-active stereo and omni-directional video.

This work was supported by the FederalMinistry of Education and Research undergrant 03WKJ02C.

Aljoscha Smolic (smolic@hhi.de)

Multiple View Traffic Surveillance with 3D Scene Reconstruction

Visual surveillance systems have become very common and accepted in modern society.An important special case is traffic surveillance, where for instance a crossing is observedby a number of cameras. A system for multiple view traffic surveillance has been devel-oped, including several remotely controllable video servers and a multi-client. We alsopresent further advanced functionalities that can be provided if multiple views of a trafficscene are available. A complete interactive 3D model of the scene is constructed.

Scenario for multiple

view traffic surveillance

and video streaming

using a WLAN

96

MPEG-4 defines compression schemes foraudio and video streams at a wide range ofchannel data rates. Therefore it has also beenadopted for the next generation of visualcommunication systems for mobile environ-ments such as 3GPP. The variety of imple-mentations of MPEG-4 systems range frompure software solutions to application-specif-ic processor systems. Pure software solutionsrequire large processing power and aretherefore mainly restricted to run on PCs.Application-specific processors allow a hard-ware-efficient implementation and are there-fore the choice for compact and power-sen-sitive solutions, as required for example inmobile applications.

In the figure the overall architecture of thecomplete MPEG-4 Simple Profile video codecis shown. This has been implemented in co-operation with a German IP company.

Based on a hardware-software partitioning,parts of the video codec algorithm aremapped onto a programmable processorwhile others are mapped to dedicated hard-ware modules.

The video input module (M4VI) comprisesa camera interface, and also scalers in thegeneral case. The video output unit providespicture scaling and colour conversion, an on-screen display (OSD) unit and an LCD inter-face. A motion estimation module (M4ME)can be used to avoid the computationally in-tensive calculation of motion vectors by theprocessor. A similar option holds for thepost-filter task, for which a video enhancermodule (M4VENH) is provided. The dataflow is controlled by interrupts, which areprocessed by an interrupt control unit. Acommon SRAM is used for the exchange of

data between the processor and the varioushardware modules.

The main advantage of the proposed sys-tem architecture, which is based on dedicat-ed hardware accelerators, is the large reduc-tion of the load on the main processor.

Another major advantage of this architec-ture is the very low power consumption,which is mainly due to the hardware acceler-ators. They greatly lower the processor loadin comparison to a pure software solution.The power consumption is lowered furtherby several power-down modes.

A more detailed description of the MPEG-4codec can be found in [1].

[1] B. Stabernack, M. Köhler, M.Reißmann, G. von Cölln, “A processor basedsystem on a chip design for mobile multimedia applications”, IEEE International Sym-posium on Consumer Electronics ICE 02, TU-Ilmenau, Germany, 24-26 September 2002.

Benno Stabernack (stabernack@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

An MPEG-4 Video Codec ASIC for Mobile Applications

Mobile multimedia is predicted to be one the major applications for future broadbandmobile networks such as UMTS. As well as pure streaming applications for unidirectionalcommunication, bidirectional applications such as video teleconferencing and multimediamessaging will become increasingly popular.

Block diagram of the

MPEG-4 video codec

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In recent years several video coding stan-dards such as H.261/3 and MPEG-1/2 havebeen introduced. These mainly address thecompression of generic video data for digitalstorage and communication services. Theseschemes, including the future standardH.264, are designed on the basis of the sta-tistics of the video signal without knowledgeof the semantic content. By contrast, model-based codecs [1] are based on the semanticsof the scene. Higher coding efficiency can beachieved by using 3D computer models torepresent the objects in the scene. For thetypical class of head-and-shoulder scenes fre-quently found in applications such as video-telephony or video-conferencing systems, bitrates of 1 kbit/s with acceptable quality havebeen reported [1].

In a model-based codec a generic 3D headmodel specifying the shape and colour of theperson in the video is adapted to the individ-ual. The texture and geometry of the faceobject are encoded only once and transmit-ted to the decoder. Subsequently, 3D mo-tion and the facial expressions of the personare estimated from each frame of the imagesequence. A set of facial animation parame-ters (FAPs) defines, together with the headmodel, the current appearance of the per-son. The MPEG-4 standard [2] defines such aparameter set and allows standard-compliantfacial animation. The parameter set is thenencoded and streamed over the network. Atthe decoder, the 3D head model is deformedaccording to the FAPs and new frames are syn-thesized using computer graphics techniques.

Although decoding of FAPs and animationof 3D head models for model-based codingare standardized in MPEG-4, no informationis provided in the standard about how to de-termine the FAPs from an image at the en-coder, and satisfying model-based codingsystems are still very rare. At the HHI a newmodel-based coding system using MPEG-4has been developed that targets high qualityencoding of head-and-shoulder scenes at bitrates of a few kilobits per second. New meth-ods have been developed to robustly esti-mate the 3D motion and deformation para-meters from monocular image sequences.

The figure illustrates the quality of thecodec. The first row shows the original se-quence while the second row shows the ani-mated wireframe model. Texture mappinggenerates natural-looking synthetic frames,as shown by the decoder output in the thirdrow. As well as leading to an extremely lowbit rate, which allows the transmission ofvideo streams even over low-bandwidthwireless channels, the semantic representa-tion simplifies interaction with and modifica-tion of the scene content. For example, inthe last row of the figure the head model atthe decoder is replaced by that of a differentperson, which enables new applications incharacter animation and film production.

[1] P. Eisert and B. Girod, “Analyzing facialexpressions for virtual conferencing”, IEEEComputer Graphics & Applications, vol. 18,no. 5, pp. 70-78, September 1998.

[2] ISO/IEC 14496-2, Coding of Audio-Visual Objects – Part 2: Visual (MPEG-4 Video),International Standard, doc. N3056.

Peter Eisert (eisert@hhi.de)

3D Model-Based Coding of Video using MPEG-4

A new system for the encoding of head-and-shoulder video sequences at bit rates of afew kilobits per second is presented. 3D computer models are used to represent the per-son in the scene and MPEG-4 animation parameters are used to define temporal changesof facial expressions. Extremely low bit rates and simple access to the semantic informa-tion enable a wide variety of new applications.

Original sequence

Animated wireframemodel

Decoded frames

Animation of arbitrary

people

98

The dynamic expansion of the multimediamarket is accompanied by a demand for im-proved video performance. The newesttrends suggest a future need for high qualityreproduction of video on TV and HDTV dis-plays as well as on desktop screens. As a con-sequence, the requirements for video repro-duction are growing, accelerated not only atthe high end, but also in the consumer mar-ket. Nevertheless, current practice is disap-pointing. Most TV screens and video projec-tors show annoying interline and screen flick-

er. Also, computer displays suffer from insuffi-cient resolution of videos and show motionjudder.

Some of these problems could be reducedsimply by increasing the computational pow-er and bus bandwidth. However, some ofthem cannot. Problems related to the basicvideo standards and incompatibility withmultimedia display formats cannot be over-come by operation at higher data rates orimprovements in computation speed. Theycan only be solved by image format conver-sion. To answer this challenge, a high qualityimage converter of moderate complexity hasbeen developed at the Heinrich-Hertz Insti-tute. It provides the highest possible videoquality without loss of resolution or motionjudder.

In general, the basic motion compensationalgorithm (an HHI patent) can be used to

perform the conversion of any digital videoand graphic standard format into any other.This allows numerous video sources to beadapted to different displays.

There are two implementations of the con-verter, a real-time hardware version and anon-real-time software version. The real-timeimplementation is designed as a simulatednetlist based on the VHDL description lan-guage. It may be integrated onto a singlechip or as an FPGA solution. The features arelimited to HD/HD conversion.

The software implementation of the videoconverter HiCon32 provides the greatest flex-ibility for the conversion parameters. It iseasy to use and offers the customer a widerange of applications. User control is per-formed through a graphic user interface. It isa WIN32-based implementation, and is alsoportable to UNIX/LINUX. At this stage it isnot real-time.

The main area of application is postpro-duction, where the electronic image se-quences must be adapted to the final targetformat while preserving the highest possiblepicture quality. It may also be used as plug-infor editing systems or similar image process-ing software, or used as a standalone soft-ware tool.

Martin Hahn (hahn@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

Multi-Standard Motion Compensated Image Format Converter HiCon32

The motion compensating image sequence converter developed in this project convertsbetween different image sequence formats. It performs deinterlacing while preservingfull spatial resolution. Furthermore, image rate conversion is accomplished with motionportrayal that is adequate for high quality image applications such as digital cinema. Thisis the basic requirement for the optimal flicker-free and judder-free driving of high-enddisplays.

Conversion

of video sources to

output displays

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The main goal is the implementation of anMPEG-4 Simple Profile codec at QCIF resolu-tion and a decoder at CIF resolution. At thesame time the processor module must en-code and decode MPEG-4 AAC (AdvancedAudio Coding) stereo bit streams at highquality. This audio coding standard deliversexcellent compression performance and sup-ports sampling rates from 8 to 96 kHz. Itgives high quality audio at a low bit rate (64kbit/s per channel). The high coding efficien-cy of AAC is achieved by a combination ofseveral new techniques (adaptive high reso-lution filter banks, temporal noise shaping,adaptive prediction, and entropy coding).These computationally expensive algorithmsmake it difficult to implement the encodingprocess for real-time applications. The algo-rithms and the module architecture in thisdevelopment have been optimized for thispurpose.

A module based on the Intel StrongARM(SA-1110) has been developed for evaluationin this application. The SA-1110 processor isoptimized for portable and embedded appli-cations. It incorporates a 32 bit StrongARMRISC processor capable of running at up to206 MHz. It contains an MMU, an LCD con-troller, and serial I/O, all combined in a sin-gle component. The video processing mod-ule captures video input from a CIF sourceand outputs images to an LC display at amaximum rate of 30 frames per second.

The module supports a graphical user in-terface and includes decoders for AAC, MP3,CELP and MPEG-4 video. The algorithms wereported and optimised for the StrongARMprocessor architecture, resulting in high-per-formance implementations.

The board that has been developed hasthe following resources and features:• 32 Mbyte flash memory• Up to 64 Mbyte SDRAM• Ethernet 10/100 Mbit/s• USB host and slave• LCD display (320 x 240)• PAL/NTSC interface• Debug/JTAG interface• Compact flash socket• Input/output for analogue audio data• Module dimensions 142 x 98 mm2

Two inputs for analogue audio data areavailable: stereo LINE IN and MIC IN. A highfidelity 16 bit audio ADC/DAC converts ana-logue data into digital data and vice versa.

This project is supported by the FederalMinistry of Education and Research (BMBF)under grant 01 AK 001.

Maati Talmi (talmi@hhi.de)

Processor Module based on StrongARM for Audio and Video Applications

System level low power modules capable of supporting MPEG-4 image compression anddecompression, together with high quality sound, are indispensable for battery-poweredhand-held systems. For this purpose a small module based on a StrongARM RISC proces-sor has been developed and evaluated for various applications.

StrongARM module

100

VIRTUE has developed new and innovativetechnology to produce a convincing percep-tion of presence in a 3-way telepresencevideo conferencing system. The objective ofthe project was to create a system that al-lows many participants located in differentgeographical places to meet around a virtualtable. The appearance of remote speakers issuch that local participants have the impres-sion that they are present in the same room.The purpose is to enable the participants tomake use of rich communication modalitiesclose to those used in face-to-face meetings(e.g. gestures, eye contact, realistic images,correct sound directions, etc) and to elimi-nate the limits of non-immersive tele-confer-encing, which impoverish communication(e.g. face-only images in separate windows,unrealistic avatars, no eye contact) or skewthe participants’ balance (e.g. some partici-pants appearing larger than others, or inprivileged positions on screen). During theproject we identified the potential as well asthe limits of current technology to createsuch a videoconferencing system.

We can now present the first prototype ofour system, which is developed for a three-party video-conferencing situation. A photo-graph of the system is seen in the figure,which shows the large plasma display, fourcameras mounted around the display andloudspeakers beside it. The real table contin-ues seamlessly into the virtual working spaceand the remote participants are representedin correct size and perspective. This will beachieved by very complex multi-view videoprocessing, which consists of 3D analysis ofthe captured video streams and synthesis ofthe virtual views at the receiver side, depend-ing on the viewer’s perspective of the scene.Hence, a vision-based head tracker has beenimplemented. Segmentation of the remoteconferees from their backgrounds is also oneof the algorithm modules.

The transmission is currently realised by anMPEG-2 low delay encoder, specifically de-veloped for the needs of this system.

In order to perform real-time processing atfull CCIR601 resolution, the system is ex-tended by dedicated hardware based on the

TriMedia DSP. This hardware extension,called the VPS board (VIRTUE processor sta-tion), is based on a PCI interface and is there-fore flexible and modular in terms of scalabil-ity and possible redesign of the system’s ar-chitecture. All the algorithms are now able torun in real time at full resolution video, en-suring the highest possible quality of videothroughout the system.

The VIRTUE consortium has developed atechnology that could have a wide range ofapplications across a number of fields – e.g.telecommunications, broadcasting, gamesand engineering. In particular, the primarygoal of high-realism video conferencing hasbeen realised with a system that is expectedto greatly enhance the effectiveness of com-munication.

This work is supported by the IST programof the EC under proposal No. IST-1999-10044.

Oliver Schreer (schreer@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

Virtual Team User Environments – a Mixed-Reality Approach toImmersive Tele-Collaboration

In the context of the European 5th framework programme IST, the project VIRTUE hasnow developed the first prototype of a real-time 3D videoconferencing system. In collab-oration with British Telecom, Sony, Heriot-Watt University, TNO and TU Delft, HHI is apartner in VIRTUE and responsible for the real-time platform.

The final VIRTUE station

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In recent years, existing software designapproaches have increasingly failed to fulfilthe needs of large and complex softwareprojects. At HHI a new infrastructure for soft-ware development has been established tosupport the following goals:

Reusability: Software has to be reusable,which means that well-designed interfacesmust be provided for all components.Software must be error-free, commonly avail-able and well documented.

Cost effectiveness: Cost effectiveness isstrongly linked to reusability. Reuse of exist-ing components allows new applications tobe created in a fast and cost-effective man-ner, thus making software developmentcompetitive.

Protection of intellectual property: Soft-ware must be protected against unwantedaccess. It is desired to make software publiclyavailable without disclosing specific know-how or giving away any rights.

Data security: Data has to be protectedagainst technical failure. An automated back-up process that grants access to earlier ver-sions of software releases can achieve this.

Professional documentation: Documen-tation must be generated by an automatedprocess that can support various output for-mats and document structures (e.g. interfacedocumentation, user manual, developer doc-umentation).

Know-How maintenance: Software mustbe findable, readable and understandable.This includes identification of consistent ver-sions and automated generation of docu-mentation.

Platform independence: Software has tobe widely platform independent and needsto support multiple operating systems to in-crease its reusability and to decrease costsand time-to-market.

Management of complex software: Thedevelopment infrastructure needs to supportdeveloper teams. A unified and documentedworkflow makes teamwork easier. Supportand training must be provided for the devel-opers.

Version management: Version informationof files and documentation must be tracked.

To reach these goals, a small expert teamhas defined and established the workingstructure illustrated in the figure.

This structure incorporates the followingfeatures:

A responsive database with version controland daily backup; a unified project structureensuring proper interactivity between soft-ware modules and teams; a developer envi-ronment and integrated developer tools tocreate reusable, stable and portable mod-ules; design tools (based on the UML stan-dard) for managing large and complex soft-ware projects; active templates for automat-ed generation of professional documentation.

The team is in charge of maintaining thetechnical infrastructure and providing all re-quired developer tools. It offers trainingcourses for beginners and advanced develop-ers and keeps the online documentation upto date. Consulting is offered, and softwaresynergies between various projects are de-tected and pointed out. Software libraries ofcommon interest are developed, maintainedand made publicly available in the database.

Jens Güther (guether@hhi.de)

Standardised Software Design for Multimedia Applications

The complexity of multimedia applications has grown significantly over the past decade.Because of this, reusable, modular and well-designed software libraries must be devel-oped to create stable, maintainable and supportable applications. This leads to cost-effec-tive software development, protects HHI’s intellectual property and reduces the time tomarket. This contribution describes the documented and guided software developmentprocess used in the Image Process Department to reach these goals.

Working structure

102

Discussions with major electronic compa-nies reveal that 3D is expected to be thenext great revolution in the history of TV. Sofar almost all approaches are based on theidea of “stereoscopic” video, i.e. the capture,transmission and display of two separatevideo streams, one for the left eye and onefor the right eye. The main drawback ofthese systems is their inflexibility regardingdepth reproduction, different display tech-nologies, and different viewing conditions.

Recent advances in a number of differentkey technologies, especially computer visionand computer graphics, allow us to over-come these restrictions and to develop anew, more flexible approach based on thejoint transmission of video and associateddepth information [1]. Monoscopic or stereo-scopic views of the scene are then generatedby means of depth-image-based rendering(DIBR) techniques. An overview of the neces-sary video processing chain is shown in thefigure.

The 3D video data are generated by eitherrecording new content using a novel depthcamera or by converting existing 2D videomaterial to 3D (3D Content in the figure).The video and the associated depth informa-tion are then transmitted in a way that isbackwards compatible to current 2D digitalTV (Coding and Transmission). At the receiv-

er side, one or more virtual views are synthe-sised using DIBR techniques to reproduce thescene on future auto-stereoscopic single ormulti-user displays. Alternatively, head-mo-tion parallax can be provided even on con-ventional 2D displays to provide the viewerwith some initial, limited impression ofdepth. This allows for the evolutionary intro-duction of depth perception into the existing2D digital TV framework.

Another point that should be mentioned is

that the new approach also provides scalabil-ity in terms of depth perception. This is par-ticularly important because perception stud-ies have indicated that there are differencesin depth appreciation across the age groups.

This work is supported by the EuropeanCommission (EC) through the InformationSociety Technologies (IST) program underproposal No. IST-2001-34396.

[1] C. Fehn, P. Kauff, M. Op de Beeck, F.Ernst, W. IJsselstein, M. Pollefeys, L. VanGool, E. Ofek and I. Sexton, “An evolutionaryand optimised approach on 3D-TV”, Proc.IBC ‘02, Amsterdam, Netherlands, Sept.2002.

Christoph Fehn (fehn@hhi.de)

H H I R E P O R T 2 0 0 2 · S E L E C T E D C O N T R I B U T I O N S · E L E C T R O N I C I M A G I N G …

A Concept for 3D TV

We present the concept of a novel 3D-TV system that allows for the evolutionary intro-duction of depth perception into the existing digital TV framework. The approach isbased on the joint transmission of video and associated depth information. Monoscopicor stereoscopic “virtual” views of the scene are generated by means of depth-image-based rendering (DIBR) techniques.

Outline of the video

processing chain for a

new approach to 3D-TV

103H H I R E P O R T 2 0 0 2

Communications and Events

105H H I R E P O R T 2 0 0 2 · C O M M U N I C A T I O N S A N D E V E N T S

PUBLICATIONS*

Photonic Networks

H.-G. Bach, 40 Gbit/s Photoreceivers:Development of Rx-OEICs and moduletechnology for industry partners withinthe KomNet programme (invited), Digestof 2th Sym. on Opto- and MicroelectronicDevices and Circuits, (SODC 2002), Stuttgart(DE), pp. 42-46.

H.-G. Bach, Optische Empfänger (Kap. 23),in: Handbuch der optischen Kommunika-tionstechnik (Optical Receivers (Chap. 23),in: Handbook of optical communications),E. Voges, K. Petermann (Ed.), Springer-Verlag, Berlin-Heidelberg, 2002, ISBN 3-540-67213-3.

H.-G. Bach, A. Beling, G. G. Mekonnen, W. Schlaak, Design and fabrication of 60 Gbit/s InP-based monolithic photore-ceiver OEICs and modules, IEEE J. Select.Topics Quantum Electron., 2002, vol. 8, pp. 1445-1450.

H.-G. Bach, A. Beling, G. G. Mekonnen, W. Schlaak, C. Bornholdt, 60 Gbit/s InP-based monolithic photoreceiver, Proc. 28th Europ. Conf. on OpticalCommunication (ECOC 2002), Copenhagen(DK), vol. 4, paper Th.10.5.2.

S. Bauer, O. Brox, J. Kreissl, G. Sahin, B. Sartorius, Novel optical microwavesource, Electr. Lett., 2002, vol. 38, no. 7, pp. 334-335.

S. Bauer, O. Brox, J. Sieber, M. Wolfram,Novel concept for a tunable optical microwave source, Proc. 27th Conf. OpticalFiber Communications (OFC 2002), Anaheim(CA, USA) paper ThM5.I158.

K. Biermann, D. Nickel1, K. Reimann1, M. Woerner1, T. Elsaesser1, H. Künzel,Ultrafast optical nonlinearity of low-tem-perature-grown GaInAs/AlInAs quantumwells at wavelengths around 1.55 µm,Appl. Phys. Lett., 80, (2002), p. 1936.

K. Biermann, D. Nickel1, K. Reimann1, M. Woerner1, T. Elsaesser1, H. Künzel,Ultrafast optical nonlinearity of low-tem-perature-grown GaInAs/AlInAs quantumwells at wavelengths around 1.55 µm,

Conf. on Lasers and Electro-Optics (CLEO2002), Long Beach (FL, USA), Techn. Dig.,pp. 660-661.

C. Bornholdt, J. Slovak, M. Möhrle, B. Sartorius, Application of a 80 GHz all-op-tical clock in a 160 km transmission experi-ment, Proc. Conf. Optical Fiber Communica-tion (OFC 2002), Anaheim (CA, USA), paperTuN6.

C. Bornholdt, B. Sartorius, J. Slovak, M. Möhrle, R. Eggemann, D. Rohde, G. Grosskopf, 60 GHz millimeter-wavebroadband wireless access demonstratorfor the next-generation mobile Internet,Proc. Conf. Optical Fiber Communication(OFC 2002), Anaheim (CA, USA), paper TuV4.

C. Bornholdt, J. Slovak, B. Sartorius, Novelall-optical 3R regenerator concept demon-strated at 40 Gbit/s, Proc. Conf. OpticalFiber Communication (OFC 2002), Anaheim(CA, USA), post deadline paper.

D. Breuer2, N. Hanik2, C. Caspar, F. Raub, G. Bramann, M. Rohde, E.-J. Bachus, S. McLeod3, M. Edwards3, WDM-transmis-sion over mixed fiber infrastructures, Proc.ECOC 2002, Copenhagen (DK), vol. 3, paper P.28.

D. Breuer2, N. Hanik2, C. Caspar, F. Raub, G. Bramann, M. Rohde, E.-J. Bachus, S. McLeod3, M. Edwards3, Mixed fiber in-frastructures in long haul WDM-transmis-sion, J. Opt. Comm., 2003, in press.

O. Brox, S. Bauer, G. Bramann, J. Kreissl, B. Sartorius, M. Schmidt4, K. Schuh4, B. Junginger4, E. Lach4, 160 to 40 Gb/s demultiplexing using a self-pulsating laserbased clock recovery, to appear in Proc.Conf. Optical Fiber Communications (OFC 2003), March 23-28, 2003, Atlanta(GA, USA).

O. Brox, S. Bauer, J. Kreissl, M. Möhrle, B. Sartorius, DFB-Lasers with amplified optical feedback for tunable high-frequen-cy generation, Proc. Optical Amplifiers andApplications (OAA 2002), Vancouver (CA),OWC 2.

H. Buchta, C. Gauger, E. Patzak, J. Saniter,Limits of effective throughput of opticalburst switches based on semiconductoroptical amplifiers, to appear in Proc. Conf.

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Optical Fiber Communication (OFC 2003),March 23-28, 2003, Atlanta (GA, USA).

U. Busolt, T. Tekin, C. Schubert, J. Berger, M. Schlak, B. Maul, W. Brinker, R. Molt, Ch. Schmidt, H. Ehlers, Ultrafast all-opticalsignal processing by a monolithically integrated Mach-Zehnder-Interferometer,Proc. Intern. Workshop on Optical SignalProcessing, 2001, COM, Techn. University ofDenmark, p. 10.

C. Caspar, F. Raub, E.-J. Bachus, D. Breuer2,N. Hanik2, S. McLeod3, M. Edwards3, Novelslope compensated DCF for NZDSF permits broad capacity increase for futureproof ultra-long haul WDM systems, Proc.ECOC 2002, Copenhagen (DK), PhotonicsTechnology Letters, vol. 3, paper P.21.

K. Dolzer5, T. Fischer6, C. Gauger5, M. Jäger2, M. Maier7, E. Patzak, M. Schlosser,D. Schupke6, F.-J. Westphal2, H. Woesner7,Comparison of architectures for the futureoptical internet, Proc. 3th ITG-Fachtagung“Photonische Netze”, Leipzig, 2002, p. 79.

C. Dreyer8, J. Schneider8, M. Bauer8, N. Keil,H. H. Yao, C. Zawadzki, New triazine containing polymers for use in integratedoptics, 2nd Intern. IEEE Conf. on Polymersand Adhesives in Microelectronics andPhotonics, Budapest (HU), 2002, Conf. Dig.,pp. 131-136.

C. Dreyer8, M. Bauer8, J. Bauer8, N. Keil, H. H. Yao, C. Zawadzki, Reduction of theoptical loss and optimization of polycya-nurate thermosets used in integrated optics, Microsystem Technologies, 2002,vol. 7, no. 5-6, pp. 229-238.1 Fraunhofer Institut, Teltow, D

C. Dreyer8, M. Bauer8, J. Schneider8, J. Bauer8, N. Keil, H. H. Yao, C. Zawadzki,Polymere für Anwendungen in der optis-chen Nachrichtentechnik – eineMöglichkeit zur Steigerung der Effizienzdes Internet (Polymers for optical commu-nication applications: a promise for in-creasing the internet efficiency) Forum derForschung 13, Cottbus (DE), 2002, ISSN0947-6989, pp. 26-31.

H. Ehlers, M. Schlak, U. H. P. Fischer,Packaging of integrated Mach-Zehnder interferometers for optical communicationsystems, J. of Opt. Com., (2002), in press.

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H. Feng, E. Patzak, J. Saniter, Size and cascadability limits of SOA based burstswitching nodes, ECOC 2002, Copenhagen(DK), Paper 8.5.5.

M. Ferstl, G. Fütterer9 (main author), W. Herbst10, J. Rottstegge10, M. Sebald10, J. Schwider9, Interference patterning ofgratings with a period of 150 nm at awavelength of 157 nm, Proc. SPIE's AnnualIntern. Symp. on Microlithography, 2002,vol. 4691, pp. 1703-1713.

M. Ferstl, Highly selective etching of deepsilica components using electron cyclotronresonance plasma, Micro- and Nano-Eng.2001, Eds. O. Joubert, J. Perrocheau, S.Tedesco, Elsevier, 2002, Amsterdam (NL),pp. 881-886.

M. Ferstl, S. Hohng11 (main author), J. O. White11, A. Pesch12, M. Burkhardt12, R. Brunner12, Design, fabrication and characterization of a diffractive solid immersion lens, Proc. 7th Intern. Conf. onNear-Field Optics (NFO-7), Rochester (GB),2002.

M. Ferstl, J. Lamprecht9 (main author), N. Lindlein9, J. Pfund9, J. Schwider9, Null-test-measurement of cylindrical microlenses in transmitted light, Proc.Photonics in Measurement 2002, Aachen(DE), June 2002.

S. Fidorra, H. Heidrich, E. Hilliger, B. Hüttl, R. Kaiser, M. Kroh, L. Küller, R. Ludwig, V. Marembert, W. Rehbein, S. Ritter,Characterization of ion-implanted 1.55 µmFabry-Perot lasers for application asmode-locked pulse sources, Proc. Europ.Semicond. Laser Workshop 2002,Copenhagen (DK), session 1, p. 10.

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Communication transmitter modules,University of Applied Science Harz,http://www.techonline.com/community/ed_resourse/feature_article/14811_FI3555566763UO.

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C. Gauger5, H. Buchta, E. Patzak, J. Saniter,OBS nodes – Technology meets perfor-mance, Proc. 2. TransiNet Workshop at HHI,Berlin, 2002.

K. Habel, Dispersion compensation for40 Gbit/s and 160 Gbit/s WDM-systemsusing NZ-DS-fibres, Proc. 3th ITG-Fach-tagung “Photonische Netze”, Leipzig (DE),2002, pp. 89-94.

K. Habel, Tolerances for dispersion-optimised NZ-DSF sections for 40 Gbit/sWDM-signals, Proc. Europ. Conf. onNetworks & Optical Communications (NOC 2002), Darmstadt (DE), pp. 90-94.

V. A. Haisler7, C. Möller, F. Hopfer7, R. L. Sellin7, A. Lochmann7, K. Fleischer7, N. Esser7, W. Richter7, N. Grote, N. N. Ledentsov7, D. Bimberg7, Micro-Raman studies of vertical cavity surface emitting lasers with AlxOy/GaAsdistributed Bragg reflectors, Appl. Phys.Lett., 2002, 81, 2544-6.

M. Hamacher, H. Heidrich, D. G. Rabus, U. Troppenz, InP-based high index wave-guides on GaInAsP/InP for applications inactive/passive ring resonators (invited),Proc. Photonic West, San José (CA, USA),2002, pp. 37-45.

M. Hamacher, U. Troppenz, H. Heidrich,D. G. Rabus, Active ring resonators basedon InGaAsP/In (invited), Proc. SPIE Conf.Photonic Fabrication Europe, Brugge (BE),(4947B-25)S2.

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H. G. Weber, K. Yvind15, J. Hanberg16,Improved electroabsorption demultiplexerby tandem-arrangement with semicon-ductor optical amplifier, Proc. 27th Conf.Optical Fiber Communications (OFC 2002),Anaheim (CA, USA), pp. 742-743.

J. Honecker17, A. Umbach17, D. Trommer17,Th. Eckhardt, U. H. P. Fischer18, High-speedphoto diode modules with up to 45 GHzmodulation bandwidth for optical com-munication systems, Optical Fiber Commu-nication (OFC 2002), Anaheim (CA, USA),Techn. Dig. ThGG80, pp. 724-725.

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K. Janiak, P. Albrecht, S. Fidorra, H. Heidrich,W. Rehbein, H.-L. Althaus19, 1.3 µm BH-FPlaser with integrated monitor photodiode,45° reflector for under side emission andfull on-wafer fabrication, Proc. 14th Intern.Conf. on Indium Phosphide and RelatedMaterials (IPRM 2002), Stockholm (SE), pp. 31-34.

K. Janiak, P. Albrecht, S. Fidorra, H. Heidrich,W. Rehbein, H. Roehle, H.-L. Althaus19,Bottom emitting 1.3 µm BH-FP laser with45° reflector and monitor photodiode,Proc. 18th Intern Conf. on SemiconductorLaser, (ISLC 2002), Garmisch-Partenkirchen(DE), paper WA 3.

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N. Keil, H.H. Yao, C. Zawadzki, S. Garbe, O. Radmer, M. Bauer8, C. Dreyer8, J. Schneider8, C. Uhlig8, O. Kahle8, Centralwavelength trimming of all-polymerathermal AWG multiplexer, Proc. 28th Europ.Conf. on Optical Communication (ECOC2002), Copenhagen, (DK), Conf. Dig. 6.2.3.

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B. Kuhlow, G. Pryzrembel, Silica basedPON-AWG with 2 x 8 up- and downstreamchannels, Optical Fiber Communication(OFC 2002), Anaheim (CA, USA), Techn.Dig., ThGG59, pp. 695-697.

B. Kuhlow, G. Przyrembel, H. Ehlers, G. Grosskopf, R. Eggemann, D. Rohde, Silicabased planar lightwave circuit for beamforming of mm-wave array antennas,Techn. Dig. Integrated Photonics Research2002, Vancouver (CA), paper IthG5.

B. Kuhlow, G. Przyrembel, H. Ehlers, R. Ziegler, J. Knüppel, G. Grosskopf, R. Eggemann, D. Rohde, Silica based opticalbeam former in a 60 GHz radio-over-fibresystem, Proc. Intern. Zürich Seminar onBroadband Communications, Zürich, (CH),2002, paper 25.

H. Künzel, K. Biermann1, J. Böttcher, P. Harde, M. Kurtzweg20, R. Schneider20, W. Neumann20, D. Nickel1, K. Reimann1, M. Woerner1, T. Elsaesser1, Low-tempera-ture grown 1.55 µm GaInAs/AlInAs quantum wells for optical switching: MBEgrowth and optical response, Proc. 14th

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K.-D. Langer, The German R&D programmeKomNet – On the way to the broadbandInternet, IST OPTIMIST Workshop on Trendsof Technologies for Photonic Networks,Torino (IT), Febr. 2002, http://www.ist-optimist.org/pdf/workshops/ONDM2002/ONDM2002_Langer.pdf.

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B. Liu21, A. Shakouri21, D. R. Rabus, Passivemicroring resonator coupled laser, Proc.15th IEEE/LEOS Annual Meeting, Glasgow(GB), 2002, pp. 742-743, paper ThN1, ISSN1092-8081 invited paper (Rabus as deputy ofLiu).

R. Ludwig, U. Feiste, C. Schmidt, C. Schubert,J. Berger, E. Hilliger, M. Kroh, T. Yamamoto22,C. M. Weinert, H. G. Weber, Enabling trans-mission at 160 Gbit/s, Proc. 27th Conf.Optical Fiber Communications (OFC 2002),Anaheim (CA, USA), paper TuA, pp. 1-2.

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R. Ludwig, C. Schubert, S. Watanabe22, F. Futami22, C. Schmidt, J. Berger, C. Boerner, S. Ferber, H. G. Weber, 160 Gbit/s wavelength converter with 3R-regenerating capability, Optoelectr. andCommunications Conf. (OECC 2002)Yokohama (JP), postdeadline paper PD-1-3.

G. G. Mekonnen, H.-G. Bach, W. Schlaak, R. Steingrüber, A. Seeger, W. Passenberg, W. Ebert, G. Jacumeit, Th. Eckhardt, R. Ziegler, A. Beling, 40 Gbit/s photoreceiv-er with DC-coupled output and operationwithout BIAS-T, Proc. 14th Intern. Conf.Indium Phosphide and Related Materials(IPRM 2002), Stockholm (SE), pp. 669-672.

A. M. Melo7, G. O. Toptchiyski7, K. Petermann7, C. Schubert, Crosstalkanalysis of longer SOAs for demultiplexingto the base data rate of 10Gbit/s and40 Gbit/s, Proc. IEEE Summer Topical 2002:“Fast Optical Signal Processing in opticalTransmission”, Montramplant (CA), paperuC2, pp. 11-12.

A. M. Melo7, G. O. Toptchiyski7, K. Petermann7, C. Schubert, Analysis ofADD/DROP multiplexing at 160Gbit/s tobase data rates of 10 Gbit/s and 40 Gbit/s,Proc. 28th Europ. Conf. on OpticalCommunications (ECOC 2002),Copenhagen (DK), vol. 4, paper 11.4.3.

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M. Möhrle, C. Bornholdt, O. Brox, S. Bauer,B. Sartorius, Multi-section DFB lasers forhigh speed signal processing/regeneration,Proc. Conf. Optical Fiber Communication(OFC 2002), Anaheim (CA, USA), paper TuU1.

M. Möhrle, H. Roehle, A. Sigmund, A. Suna,F. Reier, High-performance all-active tapered 1550 nm InGaAsP-BH-FP-lasers,Proc. 14th Intern. Conf. on Indium Phosphideand Related Materials (IPRM 2002),Stockholm (SE), paper A1-3.

M. Möhrle, A. Sigmund, L. Mörl, H. Roehle,A. Suna, G. Jacumeit, C. Bornholdt, F. Reier,All-active tapered 1550nm InGaAsP-BH-FP-Lasers for uncooled 10 Gb/s operation,Proc. 18th Intern. Conf. on SemiconductorLaser, (ISLC 2002), Garmisch-Partenkirchen(DE), paper TuP15.

C. Möller, J. Böttcher, H. Künzel, GaAs-based tunnel junctions (invited),Proc. 10th Intern. Symp. Nanostructures:Physics and Technology, St. Petersburg(RUS), 2002, pp. 574-576.

H.-P. Nolting, B. Sartorius, Fast clocked de-cision – a novel ultra high speed switchingtechnique, Proc. 28th Europ. Conf. onOptical Communications (ECOC 2002),Copenhagen (DK), paper 8.4.5.

G. Przyrembel, B. Kuhlow, Waveguidecrossings with low crosstalk at small angles, Electron. Lett., vol. 38, no. 24, pp.1533-1535.

G. Przyrembel, B. Kuhlow, S. Schlüter, Flat-top transmission waveguide filterwith multiple cavities, Proc. Workshop andEOS Topical Meeting on Two DimensionalPhotonic Crystals, Ascona (CH), 2002, pp. 1-20.

D. G. Rabus, M. Hamacher, H. Heidrich, U. Troppenz, Box-like filter response oftriple ring resonators with integrated SOAsections based on GaInAsP/InP, Proc. 14th

Intern. Conf. on Indium Phosphide andRelated Materials (IPRM 2002), Stockholm(SE), pp. 479-482.

D. G. Rabus, M. Hamacher, H. Heidrich, U. Troppenz, High-Q channel-dropping fil-ters using ring resonators with integratedSOAs, IEEE PTL, vol. 10, no. 10, 2002, pp.1442-1444.

D. G. Rabus, M. Hamacher, U. Troppenz, H. Heidrich, Optical filters based on ringresonators with integrated semiconductoroptical amplifiers in GaInAsP/InP, IEEEJSTE, vol. 8, no. 6, 2002.

H. Roehle, M. Möhrle, A. Sigmund, A. Suna,F. Reier, High-performance all-active ta-pered 1550 nm InGaAsP-BH-FP-lasers,Proc. 14th Indium Phosphide and RelatedMaterials Conf. (IPRM 2002), Stockholm(SE), pp. 27-30.

M. Rohde, C. Caspar, F. Raub, G. Bramann,H. Louchet, K. Habel, E.-J. Bachus, Controlmodulation technique for client indepen-dent optical performance monitoring andtransport of channel overhead, Conf.Optical Fiber Communication (OFC 2002),Anaheim (CA, USA), Techn. Dig., PaperTuE2, pp. 21-22.

M. Rohde, Performance monitoring oftransparent WDM networks by RF controlsignals, Proc. 3th ITG-Fachtagung “Photoni-sche Netze”, Leipzig (DE), 2002, pp. 165-170.

M. Rohde, C. Caspar, F. Raub, E.-J. Bachus,Transparent performance monitoring andchannel identification by a new client in-dependent control modulation technique,Electron. Letters, vol. 38, no. 12, 2002, pp. 587-588.

M. Rohde, F. Raub, E.-J. Bachus, Monitoringof transmission impairments in long-haultransmission systems using the novel digital control modulation technique,Proc. ECOC 2002, Copenhagen (DK), vol. 3,paper 13.

Th. Rosin, Entwicklung und Aufbau von100 GHz-Fotoempfängern (Developmentof 100 GHz photoreceiver),www.hhi.de/avt/HF-OEAVT/main.html, 2002.

Th. Rosin, Simulation of optical elementswith 2D-Raytracing for GPIB device dri-ving (geometrical optics under LabVIEW),Nat. Instruments 7. Anwenderkongress “VIP2002 Virtuelle Instrumente in der Praxis”,Hüthig (DE), pp. 84-89.

B. Sartorius, S. Bauer, C. Bornholdt, O. Brox,M. Möhrle H.-P. Nolting, J. Slovak, All-opti-cal clock recovery for signal processingand regeneration, Proc. IEEE SummerTopical 2002: “Fast Optical Signal Processing

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C. Schmidt, F. Futami22, S. Watanabe22, T. Yamamoto22, C. Schubert, J. Berger, M. Kroh, H.-J. Ehrke, E. Dietrich, C. Börner, R. Ludwig, H. G. Weber, Optical Q-factormonitoring at 160 Gb/s using an opticalsampling system in an 80 km transmissionexperiment, Proc. Conf. on Lasers andElectro-Optics (CLEO 2002), Long Beach(CA, USA), pp. 579-580.

C. Schmidt, F. Futami22, S. Watanabe22, T. Yamamoto22, C. Schubert, J. Berger, M. Kroh, H.-J. Ehrke, E. Dietrich, C. Börner, R. Ludwig, H. G. Weber, Complete opticalsampling system with broad gap-freespectral range for 160 Gbit/s and320 Gbit/s and ist application in a trans-mission system, Proc. 27th Conf. OpticalFiber Communications (OFC 2002), Anaheim(CA, USA), paper ThU1.

C. Schmidt, C. Schubert, S. Watanabe22, F. Futami22, R. Ludwig, H. G. Weber,320 Gb/s all-optical eye diagram samplingusing gain-transparent ultrafast-nonlinearinterferometer (GT-UNI), Proc. 28th Europ.Conf. on Optical Communications (ECOC2002), Copenhagen (DK), paper 2.1.3.

C. Schubert, S. Diez, H. J. Ehrke, R. Ludwig,J. Berger, Comparison of interferometricall-optical switches for demultiplexing applications in high-speed OTDM system,IEEE J. of Lightw. Techn., 2002, vol. 20, no. 4, pp. 618-624.

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H. G. Weber, R. Ludwig, Ultrafast OTDMtransmission technology with advancedoptical devices, Proc. 9th Intern. WorkshopFemtosecond Technology (FST 2002),Tsukuba (JP), pp. 1-4.

H.G. Weber, R. Ludwig, U. Feiste, C. Schmidt,E. Hilliger, C. Schubert, J. Berger, M. Kroh, T. Yamamoto22, High-speed all-optical signalprocessing in optical communication sys-tems, Proc. Conf. on Lasers and Electro-Optics(CLEO 2002), Long Beach (FL, USA), p. 610.

H. G. Weber, R. Ludwig, C. Schmidt, C. Schubert, J. Berger, E. Hilliger, M. Kroh, V. Marembert, C. Boerner, S. Ferber, H. J. Ehrke, 160 Gbit/s TDM-transmissiontechnology, Proc. 28th Europ. Conf. onOptical Communications (ECOC 2002),Copenhagen (DK), paper 2.1.1.

C. M. Weinert, R. Ludwig, H. G. Weber,Nonlinear loop mirror for noise squeezingand pulse shaping, Proc. 27th Conf. OpticalFiber Communications (OFC 2002), Anaheim(CA, USA), paper ThGG48, pp. 679-680.

P. Wolfram, D. Franke, W. Ebert, N. Grote,MOVPE-based in-situ etching of InP epi-taxial heterostructures (invited), Proc. 14th

Indium Phosphide and Related Materials Conf.(IPRM 2002), Stockholm (SE), pp. 331-334.

P. Wolfram, E. Steimetz23, W. Ebert, B. Henninger23, J.-T. Zettler23, Growth ofInGaAsP/InP-laser structures monitored byusing RAS techniques, IC MOVPE XI, Berlin,2002, Mon-C3, p. 65, J. Cryst. Growth, in press.

T. Yamamoto22, C. Schmidt, E. Dietrich, C. Schubert, J. Berger, R. Ludwig, H. G. Weber, 40 GHz optical clock extrac-tion from 160 Gbit/s data signals usingPLL-based clock recovery, Proc. 27th Conf.Optical Fiber Communications (OFC 2002),Anaheim (CA, USA), paper TuN5.

T. Yamamoto22, C. Schmidt, E. Dietrich, C. Schubert, J. Berger, R. Ludwig, H. G. Weber, 40 GHz optical clock extrac-tion from 160 Gbit/s data signals usingPLL-based clock recovery, The 2002 IEICEGeneral Conf., Waseda University, Tokyo (JP),paper B-10-172, Communications 2, p. 609.

H. H. Yao, N. Keil, O. Radmer, C. Zawadzki,M. Bauer8, C. Dreyer8, J. Schneider8,Athermal all-polymer arrayed waveguidegrating multiplexer (invited), Optical FiberCommunication (OFC 2002), Anaheim (CA, USA), Conf. Dig. TuC1.

H. H. Yao, N. Keil, O. Radmer, C. Zawadzki,M. Bauer8, C. Dreyer8, J. Schneider8,Polymeric optical devices for the informa-tion society: today and tomorrow (invited),11th Polymer Materials Forum (PMF), Tokyo(JP), 2002, Conf. Dig., pp. 31-32.

H. H. Yao, C. Zawadzki, N. Keil, M. Bauer1,C. Dreyer8, J. Schneider8, Polymer wave-guide devices (invited), Conf. on Lasers andElectro-Optics (CLEO 2002), Long Beach(CA, USA), Conf. Dig. CThM1.

C. Zawadzki, H. H. Yao, N. Keil, S. Garbe, O. Radmer, M. Bauer8, C. Dreyer8, J. Schneider8, Athermal all-polymer ar-rayed-waveguide gratings (invited), 11th

Intern. Plastic Optical Fiber Conf. (POF2002), Tokyo (JP), Conf. Dig., pp. 231-234.

Mobile Broadband Systems

H. Boche, E. Jorswieck, Optimal transmitstrategies for MIMO systems with partialchannel state information, Proc. of SPIEEmerging Technologies for Future Genera-tion Wireless Communications, ITCOM,Boston (USA), 2002, vol. 4869, pp. 73-84.

H. Boche, E. Jorswieck, On the optimality-range of beamforming for MIMO systemswith Covariance Feedback, IEICE Trans. onFundamentals of Electronics, Communica-tions and Computer Sciences, vol. E 85-A,no. 11, pp. 2521-2528.

H. Boche, E. Jorswieck, Sum capacity opti-mization of the MIMO Gaussian MAC,Proc. WPMC 2002, on CD-ROM.

H. Boche, E. Jorswieck, On the Schur-con-cavity of the ergodic and outage capacitywith respect to correlation in multi-anten-na systems with no CSI at the transmitter,Proc. Conf. on Communication, Control, andComputing, Allerton (IL, USA), 2002, on CD-ROM.

H. Boche, E. Jorswieck, Analysis of diversity

and multiplexing tradeoff for multi-anten-na systems with covariance feedback,Proc. Vehicular Technology Conference VTCFall 2002, Vancouver (CA), on CD-ROM.

H. Boche, E. Jugl, Dwell time modeling forwireless communication systems andproblems of the velocity distribution,Europ. Trans. on Telecommunications,vol. 13, no. 3, 2002, pp. 269-278.

H. Boche, E. Jugl, Influence of discontinu-ous transmission and power control onthe average SIR and the outage probabili-ty of the uplink of CDMA systems, WirelessPersonal Communications,20,’02,pp.285-303.

H. Boche, M. Schubert, A general dualitytheory for uplink and downlink beam-forming, IEEE Vehicular Techn. Conf. (VTC)Fall, Vancouver (CA), 2002, on CD-ROM.

H. Boche, M. Schubert, Analysis of SIR-based downlink beamforming, IEICE Trans.Commun., 2002, E85-B(6), pp. 1160-1168.

H. Boche, M. Schubert, Comparison of infinity-norm and 1-norm optimization formulti-antenna downlink transmission,Proc. IEEE Intern. Symp. on Inf. Theory (ISIT 2002), Lausanne (CH), p. 452.

H. Boche, M. Schubert, Multi-antennadownlink transmission with individualSINR receiver constraints for cellular wireless systems, Proc. ITG 4th Intern. Conf.on Source and Channel Coding, 2002, Berlin(DE), pp. 159-166.

H. Boche, M. Schubert, Optimum SIR balancing using extended 1-norm beam-forming optimisation, Proc. IEEE Intern.Conf. on Acoustics, Speech, and Signal Proc.(ICASSP), Orlando (FL, USA), 2002.

H. Boche, M. Schubert, Solution of the SINRdownlink beamforming problem, Proc.Conf. on Information Sciences and Systems(CISS), Princeton (USA), 2002, on CD-ROM.

H. Boche, M. Schubert, E. Jorswieck, Tracebalancing for multiuser MIMO downlinktransmission, Proc. Asilomar Conf. onSignals, Systems and Computers, Monterey(CA, USA), 2002, on CD-ROM.

H. Boche, S. Stanczak, Iterative algorithmfor finding resource allocation in symbol-

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asynchronous CDMA channels with differ-ent SIR requirements, Proc. 36th AsilomarConf. on Signals, Systems, Computers,Monterey (CA, USA), 2002, on CD-ROM.

H. Boche, G. Wunder, Über eine Verallge-meinerung eines Resultats von Riesz übertrigonometrische Polynome auf allgemei-ne bandbegrenzte Funktionen (Concern-ing a generalisation of a result by Rieszabout trigonometric series to band-limitedsignals), Zeitschrift für angewandteMechanik und Mathematik (ZAMM), vol. 82,no. 5, 2002, pp. 347-351.

C. Bornholdt, B. Sartorius, J. Slovak, M. Möhrle, R. Eggemann, D. Rohde, G. Grosskopf, 60 GHz millimeter-wavebroadband wireless access demonstratorfor the next-generation mobile Internet,Conf. on Optical Fiber Communication (OFC 2002), Anaheim (CA, USA), paper TuV 4, Techn. Digest. pp. 148–149.

G. Grosskopf, R. Eggemann, H. Ehlers, A. Kortke, B. Kuhlow, G. Przyrembel, D. Rohde, S. Zinal, Maximum directivitybeam former at 60 GHz with optical feeder,IEEE-Trans. on Antennas and Propagation,2003, in press.

G. Grosskopf, R. Eggemann, S. Zinal, B. Kuhlow, G. Przyrembel, D. Rohde, A. Kortke, H. Ehlers, Photonic 60 GHz maxi-mum directivity beam former for smartantennas in mobile broadband communi-cations, IEEE Photon. Techn. Lett., 2002, vol. 14, no. 8, pp. 1169-1171.

G. Grosskopf, B. Kuhlow, G. Przyrembel, H. Ehlers, R. Eggemann, D. Rohde, S. Zinal,Silica based optical beam former for60 GHz array antennas, Fiber and Integrat-ed Optics, vol. 22, no. 1, 2003, pp. 35-46.

G. Grosskopf, B. Sartorius, C. Bornholdt, B. Kuhlow, G. Przyrembel, S. Zinal, D. Rohde, R. Eggemann, J. Slovak, 60 GHz-millimetre-wave generation and beam-forming in hybrid fibre-radio-systems forbroadband wireless access, The 27th trien-nial General Assembly of the InternationalUnion of Radio Science (URSI 2002),Maastrich (NL), Session D1.O.2.

G. Grosskopf, B. Sartorius, C. Bornholdt, B. Kuhlow, G. Przyrembel, D. Rohde, R. Eggemann, J. Slovak, M. Möhrle, Photonic

beamforming and optical millimeterwavegeneration in radio over fiber systems,Workshop for 32nd EuMW, “Advances inphotonics technologies for microwave appli-cations”, Milano (IT), 2002.

G. Grosskopf, B. Sartorius, C. Bornholdt, B. Kuhlow, G. Przyrembel, D. Rohde, J. Slovak, Indoor mobile broadband com-munication systems applying fibre basedmm-wave distribution and smartantennas, Proc. ITG-Workshop “Breitbandi-ge Zugangsnetze und integrierte Inhaus-netze”, HHI-Berlin, 2002, pp. 33-34.

G. Grosskopf, B. Sartorius, C. Bornholdt, B. Kuhlow, G. Przyrembel, S. Zinal, D. Rohde, R. Eggemann, H. Ehlers, J. Slovak,M. Möhrle, Components for broadbandwireless access at 60 GHz optical mm-dis-tribution and photonic beamforming, 1st

NEFERTITI European Workshop on “HighFrequency Optical Signal Generation andProcessing for Future Broadband Fiber-RadioSystems”, Duisburg (DE), 2002.

T. Haustein, Measurements of the coher-ence bandwidth in multi-antenna fadingchannels (extended abstract), VTC-Fall2002 (Vehicular Technology Conference),Vancouver (CA), 2002, on CD-ROM.

T. Haustein, C. v. Helmolt, E. Jorswieck, V. Jungnickel, V. Pohl, Performance of MI-MO systems with channel inversion, VTC Spring 2002, Birmingham (AL, USA), on CD-ROM.

E. Jorswieck, H. Boche, Characterization ofthe optimality-range of beamforming formultiple transmit and receive antennaswith covariance-feedback, Proc. CISS,Princeton (NJ, USA), 2002, on CD-ROM.

E. Jorswieck, H. Boche, On transmit diversi-ty with imperfect channel state informa-tion, Proc. ICASSP 2002, Orlando (FL, USA),pp. 2181-2184.

E. Jorswieck, H. Boche, Rate balancing forthe multi-antenna Gaussian broadcastchannel, Proc. of IEEE Intern. Symp. on SpreadSpectrum Techniques and Applications (ISSSTA 2002), Prague (CZ), pp. 545-549.

E. Jorswieck, T. Haustein, V. Jungnickel, V. Pohl, C. v. Helmolt, On the performanceof signal detection algorithms in flat

fading and frequency selective MIMOchannels, VTC Spring 2002, Birmingham(AL, USA), on CD-ROM.

V. Jungnickel, Wireless research funding inGermany, Intern. Forum on Future MobileTelecommunications and China-EU PostConf. on Beyond 3G, 2002, Beijing (CN), pp. 141-148.

V. Jungnickel, H. Boche, Wireless researchat HHI, Intern. Forum on Future MobileTelecommunications and China-EU PostConf. on Beyond 3G, 2002, Beijing (CN), pp. 218-233.

V. Jungnickel, T. Haustein, E. Jorswieck, C. v. Helmolt, On linear pre-processing inMulti-Antenna Systems, IEEE Globecom,2002, Taipei (TW), on CD-ROM.

V. Jungnickel, V. Pohl, H. Nguyen, U. Krüger,T. Haustein, C. v. Helmolt, High capcacityantennas for MIMO radio systems, WPMC2002, Honolulu (HI, USA), on CD-ROM.

V. Jungnickel, V. Pohl, S. Nönnig, C. v. Helmolt,A physical model of the wireless infraredcommunication channel, IEEE Journal onSelected Areas in Communications (JSAC),vol. 20, no. 3, 2002, pp. 631-640.

A. Kortke, G. Grosskopf, R. Eggemann, S. Zinal, B. Kuhlow, G. Przyrembel, D. Rohde, H. Ehlers, PhotonischerMaximum Directivity (MD) Beamformerfür Smart Antennas in 60 GHz BreitbandMobilfunksystemen (Photonic maximumdirectivity (MD) for smart antennas in 60 GHZ broadband mobile systems), Proc.ITG-Diskussionssitzung “Messverfahren imMobilfunk”, Kassel (DE), 2002, pp. 34-36.

V. Kravcenko, H. Boche, F. Fitzek, A. Wolisz,No need for signalling: Investigation of capacity and quality of service for multi-code CDMA systems using the WBE++ approach, 4th Intern. Workshop on Mobileand Wireless Communications Network,Stockholm (SE), 2002, pp. 110-114.

B. Kuhlow, G. Przyrembel, H. Ehlers, G. Grosskopf, R. Eggemann, D. Rohde, Silicabased planar lightwave circuit for beamforming of mm-wave array antennas, IPR '02, session IThG, Vancouver (CA),Techn. Dig. on Integrated PhotonicsResearch, paper IThG5, pp.1-3.

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B. Kuhlow, G. Przyrembel, H. Ehlers, R. Ziegler, J. Knüppel, G. Grosskopf, R. Eggemann, D. Rohde, Silica based opticalbeam former in a 60 GHz radio-over-fibresystem, Proc. Intern. Zurich Seminar onBroadband Communications 2002 (IZS '02),paper 25, pp.1-4.

V. Pohl, V. Jungnickel, T. Haustein, C. v. Helmolt, Antenna spacing in MIMOindoor channels, VTC Spring 2002,Birmingham (AL, USA), on CD-ROM.

V. Pohl, V. Jungnickel, E. Jorswieck, C. v. Helmolt, Zero forcing equalizing fil-ters for MIMO channels with intersymbolinterference, Lissabon (PT), 2002, on CD-ROM.

G. Reißig, H. Boche, P. I. Barton, On incon-sistent initial conditions for linear time-invariant differential-algebraic equations,IEEE Trans. On Circuits and Systems, I: Fundamental Theory and Applications, vol. 49, no. 11, 2002, pp. 1646-1648.

M. Schubert, An efficient algorithm for optimum joint downlink beamformingand power control, Vehicular TechnologySociety Conf. VTC 2002 Spring, Birmingham(AL, USA), on CD-ROM.

M. Schubert, H. Boche, A unifying theoryfor uplink and downlink multi-user beam-forming, Proc. IEEE Intern. Zurich Seminar,Zurich (CH), 2002.

M. Schubert, H. Boche, An efficient algo-rithm for optimum joint downlink beam-forming and power control, IEEE VehicularTechn. Conf. (VTC) spring, Birmingham (AL, USA), 2002, on CD-ROM.

M. Schubert, H. Boche, Joint 'dirty paper'pre-coding and downlink beamforming,Proc. IEEE Intern. Symp. on Spread SpectrumTechniques and Applications (ISSSTA),Prague (CZ), 2002, vol. 2, pp. 536-540.

M. Schubert, H. Boche, SIR balancing formultiuser downlink beamforming – a con-vergence analysis, Proc. Intern. Conf. Comm.(ICC), New York (NY, USA), April 2002.

A. Sezgin, E. Jorswieck, Joint decoding andchannel estimation for low-complexitySTC, Asilomar 2002, Pacific Grove (CA, USA),on CD-ROM.

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S. Stanczak, H. Boche, On resource alloca-tion in asynchronous CDMA channels,Proc. Intern. Symp. on Information Theory(ISIT), Lausanne (CH), 2002, p. 80.

S. Stanczak, H. Boche, On sequence sets forCDMA channels with a small delay spread,Proc. 36th Asilomar Conf. on Signals, Systems,and Computers, Monterey (CA, USA), 2002,on CD-ROM.

S. Stanczak, H. Boche, Optimal signaturesequences for asynchronous CDMA sys-tems with fixed signal delays, Proc. 5th

Intern. Symp. on Wireless Personal Multi-media Communications (WPMC 2002),Honolulu (HI, USA), on CD-ROM.

S. Stanczak, H. Boche, Sequences withsmall aperiodic correlations in the vicinityof the zero shift, Proc. ITG 4th Intern. Conf.on Source and Channel Coding, Berlin (DE),2002, pp. 183-190.

S. Stanczak, H. Boche, QS-CDMA: A poten-tial air interface candidate for 4G wirelesscommunications, Proc. of SPIE EmergingTechnologies for Future Generation WirelessCommunications (ITCOM 2002), Boston(MA, USA), vol. 4869, pp. 137-148.

G. Wunder, H. Boche, A baseband modelfor computing the peak-to-average powerratio in OFDM systems, Proc. ITG 4th Intern.Conf. on Source and Channel Coding, 2002,Berlin (DE), pp. 273-280.

G. Wunder, H. Boche, Estimating the effectof the HPA non-linearity on the symbol error rate in OFDM transmission, Proc. ofSPIE Emerging Technologies for Future Gener-ation Wireless Communications (ITCOM 2002),Boston (MA, USA), vol. 4869, pp. 13-22.

G. Wunder, H. Boche, Peak magnitude ofoversampled trigonometric polynomials,Frequenz, vol. 56, no. 5-6, 2002, pp. 102-109.G. Wunder, H. Boche, Peak value estima-tion of band-limited signals from its samples with application to the peak-to-average power problem in OFDM, Proc.IEEE Intern. Symp. on Inf.-theory (ISIT), July2002, Lausanne (CH), p. 17.

G. Wunder, H. Boche, The impact of non-linear devices on the symbol error rate inbroadband OFDM, VTC Fall 2002,Vancouver (CA), on CD-ROM.

G. Wunder, S. Stanczak, H. Boche, Channelestimation for the uplink of CDMA sys-tems with linear MMSE estimators: Lowerbounds, optimal sequences, Proc. IEEEIntern. Symp. on Spread-Spectrum Tech-niques and Applications (ISSSTA 2002),Prague (CZ), vol. 1, pp. 34-38.

Electronic Imaging Technology forMultimedia

S. Askar, P. Kauff, N. Brandenburg, O. Schreer, Fast adaptive upscaling of lowstructured images using a hierarchical fill-ing strategy, Proc. of VIPromCom 2002, 4th EURASIP IEEE Intern. Symp. on VideoProcessing and Multimedia Communica-tions, Zadar (HR), pp. 289–295.

M. Op de Beeck25, P. Wilinski25, C. Fehn, P. Kauff, Towards an optimized 3D broad-cast chain, Proc. ITCOM 2002, 3D-TV, Video& Display, SPIE Intern. Symp., Boston (MA, USA), pp. 42-50.

C.-L. Chang26, P. Eisert, B. Girod26, Using a3D shape model for video coding, Proc. 7th

Intern. Workshop Vision, Modeling, and Vis-ualization, Erlangen (DE), 2002, pp. 291-298.

E. Cooke, P. Kauff, O. Schreer, Multiple narrow-baseline system for immersiveteleconferencing, Proc. of VIPromCom2002, 4th EURASIP IEEE Intern. Symp. onVideo Processing and Multimedia Commu-nications, Zadar (HR), pp. 367-370.

E. Cooke, P. Kauff, O. Schreer, Image-basedrendering for tele-conference systems,Proc. of 10th Intern. Conf. on ComputerGraphics, Visualization and Computer Vision(WSCG 2002), Plzen (CZ), pp. 119-126.

P. Eisert, Model-based camera calibrationusing analysis by synthesis techniques,Proc. 7th Intern. Workshop Vision, Modeling,and Visualization, Erlangen (DE), 2002, pp. 307-314.

J. Faber, Offene Fragen der Human-Factors-Forschung: Barrieren bei der erfolgreichenNutzung der Informationstechnik(Unsolved questions of Human FactorsResearch: Obstacles of usabilities), FORUMWare 30 (2002), no. 1-4, Essen (DE) andVienna (AT), pp. 1-4.

J. Faber, K. Chantelau27, T. Sikora, Trends inder Informations- und Kommunikations-technik der Gegenwart: Auswirkungen aufpsychologische Forschungs- und Entwick-lungsarbeiten an Beispielen (Trends with-in information– and communication tech-nology: effects on psychological and developmental projects), H.-P. Brauns(Ed.), Zentenarbetrachtungen – HistorischeEntwicklungen in der neueren Psychologiebis zum Ende des 20. Jahrhunderts, Berlin,pp. 239-252.

C. Fehn, E. Cooke, O. Schreer, P. Kauff, 3D analysis and image-based renderingfor immersive TV applications, SignalProcessing: Image Communication Journal,Special Issue on Image Processing Tech-niques for Virtual Environments and 3DImaging 2002, vol. 17, issue 9, pp. 705-715.

C. Fehn, P. Kauff, Interactive Virtual ViewVideo (IVVV) – The bridge between im-mersive TV and 3D-TV, Proc. SPIE ITCom:Three-Dimensional TV, Video and Display,Boston (MA, USA), 2002, pp. 14-25.

C. Fehn, P. Kauff, M. Op de Beeck25, F. Ernst25, W. Ijsselsteijn28, M. Pollefeys29, L. Van Gool29, E. Ofek30, I. Sexton31, An evo-lutionary and optimised approach on 3D-TV, Proc. of Int. Broadcast Convention(IBC 2002), Amsterdam (NL), pp. 357-365.

I. Feldmann, S. Askar, N. Brandenburg, P. Kauff, O. Schreer, Real-time segmenta-tion for advanced disparity estimation inimmersive videoconference applications,Proc. 10th Intern. Conf. on ComputerGraphics, Visualization and Computer Vision(WSCG 2002), Plzen (CZ), pp. 171-178.

M. Flierl26, T. Wiegand, B. Girod26, Rate-constrained multihypothesis prediction formotion-compensated video compression,IEEE Transactions on Circuits and Systems forVideo Technology, vol. 12, no. 11, 2002, pp. 957-969.

C. Grünheit, A. Smolic, T. Wiegand, Efficientrepresentation and interactive streamingof high-resolution panoramic views, Proc.IEEE Intern. Conf. on Image Processing (ICIP 2002), Rochester (NY, USA), pp. III-209 – III-212.

C. Grünheit, A. Smolic, T. Wiegand, Virtuel-ler Tourismus – Effiziente Repräsentation

und Streaming von hochaufgelösten 360°-Panoramen (Virtual tourism – Efficientrepresentation and streaming of high-resolution 360° panoramas), Proc. 20. FKTG Jahrestagung, Zürich (CH), 2002, pp.284-299.

M. Hassenzahl7, K. Seifert7, S. Pastoor, Theeffect of “usage modes” on product appeal, Proc. Conf. on Human Factors inComputing Systems (CHI 02), Minneapolis(MN, USA), April 20-25, 2002.

G. Heising, Effiziente Bewegbildcodierungunter Verwendung einer gitterbasiertenzeitlichen Prädiktion (Efficent video cod-ing using grid based temporal prediction),PhD Thesis, TU-Berlin, Mensch & BuchVerlag, Berlin (DE), Nov. 2002, in press.

G. Heising, Efficient and robust motion estimation in grid-based hybrid video coding schemes, Proc. IEEE Intern. Conf. onImage Processing (ICIP 2002), vol. I,Rochester (NY, USA), pp. 697-700.

G. Heising, Improving coding efficiency ingrid-based hybrid video coding schemes,Proc. IEEE Intern. Conf. on Acoustics Speechand Signal Processing (ICASSP), vol. IV,Orlando (FL, USA), 2002, pp. 3269-3272.

G. Heising, G. Blättermann, D. Marpe, R. Schäfer, H. Schwarz, T. Wiegand, Invinet:Videokommunikation in verteilten Netzen(Video communication in heterogeneousnetworks), Nachrichtentechnische Zeitschrift(ntz), (jointly with Robert Bosch GmbH,Siemens AG, TU-München), VDE-Verlag,2002, pp. 40-45.

A. Joch32, F. Kossentini32, H. Schwarz, T. Wiegand, G. J. Sullivan51, Performancecomparison of video coding standards using lagrangian coder control, Proc. IEEEIntern. Conf. on Image Processing, Rochester(NY, USA), 2002.

P. Kauff, O. Schreer, Virtual team user environments – A step from tele-cubiclestowards distributed tele-collaboration inmediated workspaces, Intern. IEEE Conf. onMultimedia and Expo (ICME 2002),Lausanne (CH), on CD-ROM.

P. Kauff, O. Schreer, R. Tanger, Virtual teamuser environments – A mixed reality ap-proach for immersive Tele-Collaboration,

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Intern. Workshop on Immersive Telepresence(ITP 2002), Juan Les Pins (FR), pp. 1-4.

I. Keller, T. Meiers, T. Sikora, Relevance feed-back as distribution generation, Proc. SPIEInternet Multimedia Management SystemsIII, 2002, Boston (USA), vol. 4862, pp. 85-93.

W. Kellerer33, E. Steinbach6, P. Eisert, B. Girod26,A real-time Internet streaming media test-bed, Proc. Intern. Conf. on Multimedia andExpo ICME, Lausanne (CH), August 2002.

D. Marpe, H. Schwarz, G. Blättermann, G. Heising, T. Wiegand, Context-basedadaptive binary arithmetic coding inJVT/H.26L, Proc. IEEE Intern. Conf. on ImageProcessing (ICIP), vol. II, Rochester (NY, USA), 2002, pp. 513-516.

D. Marpe, H.L. Cycon34, High-performancewavelet-based video coding using variableblock-size motion compensation andadaptive arithmetic coding, Proc. 43th

IASTED Intern. Conf. on Signal and ImageProcessing (SIP), 2002, pp. 404-409.

D. Marpe, H. L. Cycon34, G. Zander35, K.-U. Barthel34, Context-based denoising ofimages using iterative wavelet threshold-ing, SPIE, vol. 4671, 2002, pp. 907-914.

D. Marpe, T. Wiegand, H. L. Cycon35,Design of a highly efficient wavelet-basedvideo coding scheme, SPIE, vol. 4671,2002, pp. 1133-1141.

D. Marpe, G. Blättermann, G. Heising, T. Wiegand, Efficient entropy coding forvideo compression by using context-basedadaptive binary arithmetic coding, Proc. of4th Intern. ITG Conf. on Source and ChannelCoding, 2002, pp. 297-300.

T. Meiers, T. Sikora, I. Keller, Hierarchicalimage database browsing environmentwith embedded relevance feedback, Proc. IEEE Intern. Conf. on Image Processing(ICIP 2002), Rochester (NJ, USA), vol. II, pp. 593-596.

T. Meiers, T. Sikora, J. Zimmermann, I. Keller,Hierarchical image database browsing environment with embedded relevancefeedback and three-dimensional visualiza-tion, Proc. SPIE Internet MultimediaManagement Systems III, Boston (MA, USA),2002, vol. 4862, pp. 62-73.

K. Müller, MPEG-7: Inhaltsbeschreibungvon Multimediadaten (MPEG-7: Contentdescription of multimedia data),Production Reality – Journal for broadcast,post-production, animation and content description, 2002, pp. 35-37.

K. Müller, A. Smolic, MPEG-7: Anwendungenfür die Film- und Fernsehtechnik – dasMultimedia Content Description Interface(MPEG-7: Applications for TV- and cinemaapplications:– Multimedia content descrip-tion interface), FKT – Fachzeitschrift fürFernsehen, Film und Elektronische Medien,2003, pp. 703-705.

S. Pastoor, 3D-Displays: Methoden undStand der Technik (3-D Displays: Methodsand state of the art), in: Handbuch derTelekommunikation, Deutscher Wirtschafts-dienst, Cologne (DE), 2002, vol. 4, pp. 1-51.

S. Pastoor, J. Liu, 3-D display and interac-tion technologies for desktop computing,in: “Three-Dimensional Television, Video andDisplay Technologies” by B. Javidi, F. Okano(Ed.) Springer-Verlag, Cologne (DE), 2002,pp. 315-356.

P. Ramanathan26, E. Steinbach6, P. Eisert, B. Girod26, Geometry refinement for lightfield compression, Proc. Intern. Conf. onImage Processing (ICIP 2002), Rochester (NJ, USA), pp. 225-228.

A. Redert25, M. Op de Beeck26, C. Fehn, W. Ijsselsteijn28, M. Pollefeys29, L. Van Gool29,E. Ofek30, I. Sexton31, P. Surman31, ATTEST:Advanced Three-dimensional televisionsystem technologies, Proc. of 3DPVT 2002,1st Intern. Symp. on 3D Data ProcessingVisualization Transmission, Padova (IT), pp. 313-319.

D. Ruschin, J. Faber, Im visuellen Vergleich:Analogtechnik versus digitaler Newcomer(Comparison of expressive potential:Proven analog technology versus the digi-tal newcomer), ARRI-News 04/02, München(DE), 2002, pp. 10-15.

R. Schäfer, Image processing and codingfor an immersive teleconferencing system,Intern. Symp. on Video/Image Processingand Multimedia Communications(VIPromCom '2002), Zadar (HR), pp. 7-15.

R. Schäfer, Application of new compression

techniques in digital broadcasting systems,Proc. of 14th German-Japanese Forum on IT,Bonn (DE), 2002.

R. Schäfer, MPEG-4 and H.26L: Demon-strating new coding technologies to deliv-er multimedia content via satellite, 5th

Annual Broadband via Satellite Conference,Brussels (BE), 2002, on CD-ROM.

R. Schäfer, MPEG-4 and H.26L: Improvedcompression and new functionalities en-able new application and business fields,VDE-Kongress 2002, Proc. NetWorlds,Dresden (DE), pp. 101-111.

R. Schäfer, Image compression for produc-tion and distribution of electronic film,Proc. 6. Potsdamer Filmkolleg, Potsdam (DE),September 2002.

O. Schreer, E.A. Hendriks36, J.M. Schraagen37,J. Stone38, E. Trucco39, M. Jewell40, Virtualteam user environments – A key applica-tion in telecommunication, Proc. ofeBusiness and eWork 2002, Prague (CZ), pp. 916-923.

O. Schreer, I. Feldmann, U. Goelz, P. Kauff,Fast and robust shadow detection invideoconference applications, Proc. ofVIPromCom 2002, 4th EURASIP IEEE Intern.Symp. on Video Processing and MultimediaCommunications, Zadar (HR), 2002, pp. 371-377.

O. Schreer, M. Karl, P. Kauff, PCI-based multi-processor system for immersivevideoconference terminals, Intern. IEEEConf. on Multimedia and Expo (ICME 2002),Lausanne (CH), on CD-ROM.

O. Schreer, M. Karl, P. Kauff, A TriMediaBased Multi-Processor System Using PCITechnology for Immersive Videoconfer-ence Terminals, 14th Intern. Conf. on DigitalSignal Processing (DSP 2002), Santorini (GR),July 2002, pp. 289-293.

O. Schreer, P. Kauff, An immersive 3Dvideo-conferencing system using sharedvirtual team user environments, ACMCollaborative Environments, CVE 2002, Bonn(DE), pp. 105-112

H. Schwarz, T. Wiegand, The emergingJVT/H.26L video coding standard, Proc. ofIBC 2002, Amsterdam (NL), September 2002.

H. Schwarz, T. Wiegand, An improvedMPEG-4 coder using Lagrangian codercontrol, Proc. 4th Intern. ITG Conf. onSource and Channel Coding, Berlin, 2002,pp. 301-308.

K. Seifert7, T. Baumgarten, T. Vöhringer-Kuhnt, S. Pastoor, How do you design a 3-Dinterface?, 6th Intern. Sci. Conf. On Workwith Display Units – WWDU 2002,Berchtesgaden (DE), 2002, in press.

K. Seifert7, S. Pastoor, K.-P. Timpe7, Gestal-tung von Mensch-Maschine-Systemen(Design of man-machine systems), in: T. Sommerlatte (Hrsg.): AngewandteSystemforschung. Gabler Verlag Wiesbaden,2002, pp. 101-123.

A. Smolic, Y. Vatis, T. Wiegand, Long-termglobal motion compensation applying super-resolution mosaics, Proc. IEEE Intern.Symp. on Consumer Electronics (ISCE 2002),Erfurt (DE), pp. E99-E103.

A. Smolic, Robust generation of 360°panoramic views from consumer video sequences, Proc. Intern. Symp. on Video/Image Processing and Multimedia Commun-ications (VIPromCom 2002), Zadar (HR), pp. 431-435.

B. Stabernack, H. Richter41, A multi mediastreaming framework for mobile applica-tions – A first approach, Proc. 12th Intern.Packetvideo Workshop (PV 2002), Pittsburgh(PA, USA).

B. Stabernack, H. Richter41, High qualitymultimedia streaming using MPEG-4 technology, 6th World Multiconference onSystemics, Cybernetics and Informatics (SCI 2002), Orlando (FL, USA).B. Stabernack, T. Schierl, H. Richter41, T. Rathgen42, Using RTSP/RTP and MPEG-4for streaming and bi-directional mobilemultimedia communication, IEEE Intern.Symp. on Consumer Eletronics ISCE 2002,TU-Illmenau (DE).

B. Stabernack, M. Köhler, M. Reißmann, G. v. Cölln43, A processor based system ona chip design für mobile multi media ap-plications, IEEE Intern. Symp. on ConsumerEletronics ISCE 2002, TU-Illmenau (DE).

P. Stammnitz, SAMBITS: Ein Terminal fürinteraktives Multimedia Broadcast

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(SAMBITS: Terminal for interactive multi-media broadcast), Proc. 20th FKTG-Tagung,(jointly with Institut für RundfunktechnikGmbH, Siemens AG), Zürich (CH), 2002, pp. 911-931.

P. Stammnitz, SAMBITS: Studio- und Ter-minaltechnik für interaktives Multimedia-Broadcast (SAMBITS: Studio- and terminaltechnologies for interactive multimedia-broadcast), TV- and Cinematechnik (FKT),(jointly with Institut für RundfunktechnikGmbH, Siemens AG), 56th ed., no. 08+09,2002, pp. 466-475.

P. Stammnitz, SAMBITS multimedia termi-nal, Workshop of SAMBITS: The ConvergingEnvironment of Interactive TV and Internet,IRT, (jointly with Siemens AG), München(DE), 2002.

T. Stockhammer6, D. Kontopodis6, T. Wiegand, Progressive texture videostreaming for lossy packet networks, 12th Intern. Packet Video Workshop (PV 2002), Pittsburgh (PA, USA).

T. Stockhammer6, T. Oelbaum6, T. Wiegand,H.26L video transmisson in 3G wireless environments, Intern. Conf. on ThirdGeneration Wireless and Beyond, SanFrancisco (CA, USA), 2002, pp. 25-30.

T. Stockhammer6, T. Wiegand, Optimizedtransmission of H.26L video over packet-lossy networks, IEEE Intern. Conf. on ImageProcessing, Rochester (NY, USA), September2002, in press.

REPORTS

E.-J. Bachus, Design of switchable opticalnetworks, Intermediate report on BMBF project UMTS-029-DSON, January 2002.

E.-J. Bachus, P. Weishaupt, Study on FTTDsystems, final report on an industrial contract, February 2002.

T. Behrens, Report on a practical semester2001/2002, HHI jointly with TechnischeFachhochschule Berlin, March 2002.

C. Fehn, Virtual views for immersive TV applications, Report on DFG ResearchProject SCHA 877/1-1, October 2002.

C. Fehn, K. Schüür44 I. Feldmann, P. Kauffand A. Smolic, Distribution of ATTEST Testsequences for EE4 in MPEG 3DAV, ISO/IECJTC1/SC29/WG11, MPEG02/M9219, Awaji(JP), December 2002.

C. Fehn, K. Schüür44, I. Feldmann, P. Kauff,A. Smolic, Proposed experimental condi-tions for EE4 in MPEG 3DAV, ISO/IECJTC1/SC29/WG11, MPEG02/M9016,Shanghai (CN), October 2002.

C. Fehn, A. Smolic, Study of some MPEGTools Related to 3D-Video, ISO/IECJTC1/SC29/WG11, MPEG02/M8423, Fairfax(VA, USA), May 2002.

H. Gäbler, Report on a practical semester2001/2002, HHI jointly with TechnischeFachhochschule Berlin, March 2002.

K. Grüneberg, Known algorithms for blocking artifact reduction, Report on Sub-Contract of BMWi Research Project SIPROS,February 2002.

H. Heidrich, Bidirektionale Komponentenfür den optischen Teilnehmeranschluss(Bidirectional components for the opticalsubscriber link), HHI-contribution for FinalReport on BMBF Research Projekt 01 BP 819/2by Infineon Technologies, October 2002.

G. Heising, H. Schwarz, G. Blättermann, D. Marpe, T. Wiegand, CABAC and ABT,Joint Video Team, Doc. JVT-D021, Klagenfurt(AT), July 2002.

A. Hengse45, J. Faber, R. Sniehotta et.al.,Mikroelektronik für innovative Mensch-

Maschine-Schnittstellen (Microelectronicsfor innovative man machine interfaces),Study of the Fraunhofer MicroelectronicsAlliance (VµE) including the FraunhoferInstitutes IMS, IIS-A, IZM, HHI, ESK. IGD. FIT,Berlin, December 2002.

D. Marpe, CABAC Ad Hoc Group Report,Joint Video Team, Doc. JVT-B015, Geneva(CH), January 2002.

D. Marpe, CABAC Ad Hoc Group Report,Joint Video Team, Doc. JVT-C009, Fairfax(VA, USA), March 2002.

D. Marpe, CABAC Ad Hoc Group Report,Joint Video Team, Doc. JVT-D012, Klagenfurt(AT), July 2002.

D. Marpe, CABAC Ad Hoc Group Report,Joint Video Team, Doc. JVT-E009, Geneva(CH), October 2002.

D. Marpe, G. Blättermann, G. Heising, T. Wiegand, Proposed cleanup changes forCABAC, Joint Video Team, Doc. JVT-E059,Geneva (CH), October 2002.

D. Marpe, G. Blättermann, T. Wiegand,Proposed editorial changes and cleanup ofCABAC, Joint Video Team, Doc. JVT-D019,Klagenfurt (AT), July 2002.

D. Marpe, G. Blättermann, T. Wiegand, R. Kurceren46, M. Karczewicz46, and J. Lainema46, New results on improvedCABAC, Joint Video Team, Doc. JVT-B101,Geneva (CH), January 2002.

D. Marpe, G. Heising, G. Blättermann, T. Wiegand, Fast arithmetic coding forCABAC, Joint Video Team, Doc. JVT-C061,Fairfax (VA, USA), March 2002.

D. Marpe, T. Hinz, T. Wiegand, Performancecomparison of CABAC engine and MQcoder, Joint Video Team, Doc. JVT-F040,Awaji Island (JP), December 2002.

D. Marpe, H. Schwarz, G. Blättermann, T. Wiegand, Final CABAC cleanup, JointVideo Team, Doc. JVT-F039, Awaji Island (JP),December 2002.

D. Marpe, H. Schwarz, T. Wiegand,Performance of CABAC for interlacedvideo, Joint Video Team, Doc. JVT-B100,Geneva (CH), January 2002.

D. McCutchen47, A. Smolic, SphericalEfficiency in Global Photography Mapping,ISO/IEC JTC1/SC29/WG11, MPEG02/M8678,Klagenfurt (AT), July 2002.

T. Meiers, Intelligente Informationsverwal-tung und Nutzerführung in Multimedia-Bildarchiven (Intelligent and user-adaptivesystems for navigation and retrieval of im-ages), Final Report on BMWi ResearchProject 01 MD 917/3 (I2N), HHI, Berlin,September 2002.

S. Mirghani-Hanafi, Report on a practicalsemester 2002, HHI jointly with TechnischeFachhochschule Berlin, September 2002.

L. Mühlbach, Eine Kommunikationsplatt-form für die informelle und computerun-terstützte Kommunikation bei Telearbeitund Telekooperation (A communicationplatform for informal and computer sup-ported communication in telework andtelecooperation), Final Report on BMWiResearch Project 01 MT 901/7 (KICK), HHI,Berlin, November 2002.

K. Müller, A. Smolic, Study of 3D coordinatesystem and sensor parameters for 3DAV,ISO/IEC JTC1/SC29/WG11, MPEG02/M8536,Klagenfurt (AT), July 2002.

U. Niggebrügge, A. Paraskevopoulos, M. Möhrle, N. Grote, Development of inno-vative and on-the-market efficient tech-nologies as a first step towards an indus-trial fabrication of optoelectronic compo-nents and telecom systems, Final report onOPTOFAB, Berlin, March 2002.

S, Pastoor, 3D-System mit multimodalenInteraktionen (3D system with multimodalinteractions), Final Report on BMBF ResearchProject 01 802 BK (mUltimo3D), HHI, Berlin,June 2002.

K. Schüür44, C. Fehn, I. Feldmann, P. Kauff,A. Smolic, Preliminary results on disparitycoding with in-loop median filter, ISO/IECJTC1/SC29/WG11, MPEG02/M9017,Shanghai (CN), October 2002.

K. Schüür44, C. Fehn, P. Kauff, A. Smolic,About the Impact of Disparity Coding onNovel View Synthesis, ISO/IECJTC1/SC29/WG11, MPEG02/M8676,Klagenfurt (AT), July 2002.

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H. Schwarz, D. Marpe, G. Blättermann, T. Wiegand, Improved CABAC, Joint VideoTeam, Doc. JVT-C060, Fairfax (VA, USA),March 2002.

H. Schwarz, D. Marpe, T. Wiegand, CABACand slices, Joint Video Team, Doc. JVT-D020,Klagenfurt (AT), July 2002.

H. Schwarz, D. Marpe, T. Wiegand, CABACand slices, Joint Video Team, Doc. JVT-E154,Geneva (CH), October 2002.

A. Smolic, Draft requirements for 3D video,ISO/IEC JTC1/SC29/WG11, MPEG02/M8428,Fairfax (VA, USA), May 2002.

A. Smolic, M. Droese, Results of EE1 on usage of 3D mesh objects for omni-direc-tional video, ISO/IEC JTC1/SC29/WG11,MPEG02/M8927, Shanghai (CN), October2002.

A. Smolic, C. Gruenheit, T. Wiegand,Efficient representation and interactivestreaming of high-resolution panoramicviews using MPEG-4 BIFS, ISO/IECJTC1/SC29/WG11, MPEG02/M8305, Fairfax(VA, USA), May 2002.

A. Smolic, J. Heuer48, L. Ye, P. John, P. Ogunbona49, Comments to the specifi-cation of the scalable color descriptor inISO 15938 Part 3", ISO/IECJTC1/SC29/WG11, MPEG02/M8874,Shanghai (CN), October 2002.

A. Smolic, D. McCutchen47, Requirementfor very high resolution video in 3DAV,ISO/IEC JTC1/SC29/WG11, MPEG02/M9256,Awaji (JP), December 2002

A. Smolic, R. Yamashita50, AHG on 3DAVcoding, ISO/IEC JTC1/SC29/WG11,MPEG02/M8785, Shanghai (CN), October2002.

A. Smolic, R. Yamashita50, AHG on 3DAVcoding, ISO/IEC JTC1/SC29/WG11,MPEG02/M9097, Awaji (JN), December2002.

A. Smolic, R. Yamashita50, Report of Ad hocGroup on 3DAV, ISO/IEC JTC1/SC29/WG11,MPEG02/M8679, Klagenfurt (AT), July 2002.

K.-O. Velthaus, Elektrooptische Modulato-ren für 40 Gbit/s Kommunikationssysteme

(Electro-optical modulators for 40 Gbit/scommunication systems), Final Report onResearch Project 874700001, HHI jointlywith u2t photonics AG, February 2002.

T. Wiegand, AHG Report: Working draft &joint model document & software editing,Joint Video Team, Doc. JVT-C006, Fairfax(VA, USA), March 2002.

T. Wiegand, AHG Report of text editingand software integration, Joint Video Team,Doc. JVT-D006, Klagenfurt (AT), July 2002.

T. Wiegand, AHG Report of text editingand software integration, Joint Video Team,Doc. JVT-E006, Geneva (CH), October 2002.

T. Wiegand, AHG Report of text editingand software integration, Joint VideoTeam, Doc. JVT-F006, Awaji Island (JN),December 2002.

T. Wiegand, Editor's latest draft of JVTWD2 design, Joint Video Team, Doc. JVT-C006, Fairfax (VA, USA), March 2002.

T. Wiegand, Editor’s proposed modifica-tions to joint committee draft (CD) ofjoint video specification (ITU-T Rec. H.264| ISO/IEC 14496-10 AVC), Joint Video Team,Doc. JVT-D015, June 2002.

T. Wiegand, Editor’s proposed draft modi-fications to J-CD, Joint Video Team, Doc.JVT-E020, Geneva (CH), Oct. 2002.

T. Wiegand, Editor's proposed draft textmodifications for joint video specification(ITU-T Rec. H.264 | ISO/IEC 14496-10 AVC),Geneva modifications, Joint Video Team,Doc. JVT-E146, Geneva (CH), Oct. 2002.

T. Wiegand, Joint final committee draft(JFCD) of joint video specification (ITU-TRec. H.264 | ISO/IEC 14496-10 AVC), JointVideo Team, Doc. JVT-D157, Klagenfurt (AT),July 2002.

T. Wiegand, Multi-picture handling, JointVideo Team, Doc. JVT-D018, Klagenfurt (AT),July 2002.

T. Wiegand, Study of final committee draftof joint video specification (ITU-T Rec.H.264 | ISO/IEC 14496-10 AVC), Awaji Modifications Joint Video Team, Doc.JVT-F100, Awaji Island (JP), December 2002.

PATENT APPLICATIONS

H. Boche, M. Schubert, Verfahren zur leis-tungsoptimierten Strahlformung eineseiner Basisstation zugehörigen Antennen-arrays für zellulare Mobilfunksysteme imDownlink-Kanal (Method for power-opti-mized downlink beamforming with basestation antenna arrays for cellular mobilesystems), 102 03 593.8-35

S. Askar, P. Kauff, O. Schreer, N. Brandenburg, Digitales Bildbearbei-tungsverfahren zur echtzeitfähigenBildpunktfüllung beim Vergrößern einesbekannten Bildes (Digital image process-ing for real-time interpolation in imageup-conversion), 102 04 499.6-53

I. Feldmann, P. Kauff, O. Schreer, R. Tanger,Echtzeitfähiges Erkennungs- und Kompen-sationsverfahren von Beleuchtungsschwan-kungen in digitalen Farbbildsignalen(Real-time detection and compensation ofillumination changes in digital video im-ages), 102 04 500.3-53

C. M. Weinert, Verfahren und Einrichtungzur Pulsformung in transparenten optis-chen Netzen (Device for pulse shaping intransparent optical networks), 102 12576.7-35

M. Bauer, J. Bauer, J. Schneider, Ch. Dreyer,H. Yao, N. Keil, C. Zawadzki, Temperature

T. Wiegand, Study of final committee draftof joint video specification (ITU-T Rec.H.264 | ISO/IEC 14496-10 AVC), Joint VideoTeam, Doc. JVT-F082, Awaji Island (JP),December 2002.

T. Wiegand, Text of committee draft ofjoint video specification (ITU-T Rec. H.264| ISO/IEC 14496-10 AVC), Joint Video Team,Doc. JVT-C167, Fairfax (VA, USA), March2002.

T. Wiegand, Text of committee draft ofjoint video specification (ITU-T Rec. H.264| ISO/IEC 14496-10 AVC), ISO/IECJTC1/SC29/WG11, MPEG02/N4810, Fairfax(VA, USA), May 2002.

T. Wiegand, K. Sühring, Number of allowedreference frames, Joint Video Team, Doc.JVT-F081, Awaji Island (JP), December 2002.

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1 Max-Born-Institut, Berlin, DE2 T-Systems Nova, Berlin, DE3 Corning Optical Fiber, Slintshire, GB4 Alcatel, Stuttgart, DE5 University of Stuttgart, DE6 Technical University München, DE7 Technical University Berlin, DE8 FhG IZM, Teltow, Berlin, DE9 University of Erlangen Nürnberg, DE

10 Infineon Technologies AG, Erlangen, DE11 University of Illinois, USA12 Carl Zeiss Jena, DE13 MergeOptics, Berlin, DE14 Lucent Technologies, Nürnberg, DE15 Denmark Technical University,

Kopenhagen, DK16 GiGA-Intel, DK17 u2t Photonics AG, Berlin, DE18 University of Applied Sciences,

Wernigerode, DE19 Infineon Technologies AG, Regensburg,

DE20 Humboldt-Universität zu Berlin, DE21 University of California, Santa Cruz, USA22 Fujitsu Laboratories Ldt., Wakamiya, JP23 LayTec GmbH, Berlin, DE24 Jenoptik, Jena, DE25 Philips Eindhoven, NL26 Stanford University, USA27 FH Schmalkalden, DE28 Technical University Eindhoven, NL29 Royal University of Leuven, BE30 3DV Systems, IL31 De Montfort University, GB32 UBVideo, CA

33 NTT DoCoMo, DE34 FHTW Berlin, DE35 DResearch GmbH, Berlin36 TU Delft, NL37 TNO, NL38 Sony, Basingstoke, GB39 Heriot-Watt-Univesity, GB40 BT Exact, GB41 University of Rostock, DE42 Technical University Ilmenau, DE43 SciWorx GmbH, DE44 Dicas, Berlin, DE45 Fraunhofer-Verbund Mikroelektronik,

Berlin, DE46 Nokia Research Center, Dallas, TX, USA47 Immersive Media, Portland, OR, USA48 Siemens München, DE49 Motorola, AU50 SEGA, Tokyo, JP51 Microsoft, USA

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insensitive optical waveguide devices, US 10/166,344

M. Bauer, J. Bauer , J. Schneider, Ch. Dreyer,H. Yao, N. Keil, C. Zawadzki, Tuning optis-cher Bauelemente mittels Strahlung(Method for shifting the central wave-length of optical waveguide devices by irradiation), EP 02006179.2

E.-J. Bachus, E. Schulze, Schutzeinrichtungfür eine mit Licht hoher Leistung beauf-schlagte Faserleitung (Protection meansagainst high power leakage in fibre opticlinks), 102 17 029.0-35

D. G. Rabus, Verfahren zur Parameterbe-stimmung eines optischen Filters undnach dem Verfahren hergestellte optischeFilter (A method for determining the para-meters of an optical filter and fabricatedoptical filters using this method), 102 19 244.8-51

D. Marpe, Th. Wiegand, Verfahren und An-ordnung zur tabellengestützten binärenarithmetischen Enkodierung sowie einentsprechendes Computerprogrammpro-dukt und ein entsprechendes computer-lesbares Speichermedium (Method andarrangement for table-based binary arith-metic encoding and decoding as well as acorresponding computer program and acorresponding computer readable memo-ry medium), 102 20 962.6

H. Schwarz, D. Marpe, Th. Wiegand,Verfahren und Anordnung zur Kodierungvon Transformations-Koeffizienten in Bild-und/oder Videokodierern und -dekodier-ern sowie ein entsprechendes computer-lesbares Speichermedium (A method andan arrangement for coding of transformcoefficients in image and/or video en-coders and decoders as well as a softwareproduct and a machine-readable storagemedium), 102 20 961.8

V. Pohl, Digitales lineares Entzerrfilter(Digital linear equalizing filter), 102 23445.0-35

C. Möller, Verfahren zur selektiven Oxida-tion einer Schicht in einem vertikalenBauelement (Procedure for selective oxi-dation of single layers in vertical devices),102 26 320.5-33

L. Mörl, Integrierbarer Modentransfor-mator für optische Streifenwellenleiter(Mode transformer for integration withoptical buried stripe waveguides), 102 36 798.1-51

L. Mörl, Integrierbarer Modentransfor-mator für optische Rippenwellenleiter(Mode transformer for integration withoptical rib waveguides), 102 36 800.7-51

H. Bünning, Optisches Filter und Anwen-dungen davon (Optical filter and ist appli-cations), 102 39 690.6-51

R. Steingrüber, Direktschreibendes Litho-graphieverfahren zur Herstellung einerzweidimensionalen Struktur im Submikro-meterbereich (Direct-write lithographyprocedure for the fabrication of a two-dimensional structure within the submi-crometer range), 102 43 827.7-51

A. Sezgin, E. A. Jorswieck, Signalverarbei-tungsverfahren zur empfangsseitigenRekonstruktion von Sendedatenströmenin einem MIMO-System (Signal-process-ing-algorithm for the regeneration oftransmitted data streams in a MIMO-system), 102 50 956.5

V. Jungnickel, Th. Haustein, E. Jorswieck, C. v. Helmolt, Bidirektionales Signalverar-beitungsverfahren für ein MIMO-Systemmit einer rangadaptiven Anpassung derDatenübertragungsrate (Bidirectional pro-cessing method for a MIMO system withrank-adaptive rate), 102 54 384.4

J. Schüssler, Verfahren zur bezüglich Bild-takt und Bildphase regelbaren Synchroni-sation von zwei oder mehr MPEG-2-kodier-ten Videosequenzen für digitale Multi-Projektionssysteme (Method in regard toframeclock and framephase infinitely variable synchronisation for two or moreMPEG-2 encodet videosequences for digi-tal Multi-Projection-Systemes), AKZ, 102 61 912.3

AWARDS

C. Baack, Ehrenring des VDE (“Ring ofHonour” on behalf of the “Society ofElectrical Engineering, Electronics, andInformation Technology”), Dresden, Oct.2002.

G. Blättermann, D. Marpe (together with M. Palkow and H. L. Cycon, FHTW Berlin):Prime Prize of the 5th Multimedia Start-UpCompetition 2001/2002, German FederalMinistry of Economics and Technology,Berlin, April 2002.

H. Boche, E. Jorswieck, Best-Paper-Award atWPMC 2002, for the paper “Sum CapacityOptimization of the MIMO Gaussian MAC”,Hawaii, Oct. 2002.

J. Liu, S. Pastoor, Best Patent Award of theAssociation of the Friends of the HHI for thepatent “Rechnerunterstütztes Verfahren zurberührungslosen, videobasierten Blickrich-tungsbestimmung eines Anwenderauges fürdie augengeführte Mensch-Computer-Inter-aktion und Vorrichtung zur Durchführungdes Verfahrens (Computer supportedmethod for non-contact video-based gazetracking)”, Berlin, Dec. 2002.

A. Smolic, Rudolf-Urtel-Award of theFernseh- und Kinotechnische Gesellschaft(FKTG), for the doctorate thesis “GlobalMotion Description and Video MosaicingApplying Parametric 2-D Motion Models,Estimation Algorithms and Applications”,Rheinisch-Westfälische TechnischenHochschule Aachen (RWTH), Fakultät fürElektrotechnik und Informationstechnik,Zürich (CH), June 2002.

ACCEPTANCE OF CHAIRS

H. Boche took up a professorship in thearea of communication systems, TU Berlin,Fakultät IV (Elektrotechnik und Informatik),Institut für Telekommunikationssysteme, FG Mobilkommunikation.

T. Sikora took up a professorship in thearea of communication systems, TU Berlin,Fakultät IV (Elektrotechnik und Informatik),Institut für Telekommunikationssysteme, FG Nachrichtenübertragung.

DOCTORATE THESES

G. Heising, Effiziente Bewegbildcodierungunter Verwendung einer gitterbasiertenzeitlichen Prädiktion (Efficient coding ofmoving pictures using grid-based tempo-ral prediction), Prof. P. Noll (TU Berlin,Fakultät IV), Prof. J. Ohm (RWTH Aachen).

D. G. Rabus, Realization of optical filtersusing ring resonators with integratedsemiconductor optical amplifiers inGaInAsP/InP, TU Berlin, Fakultät IV(Elektrotechnik und Informatik), Institut fürHochfrequenztechnik, Prof. Petermann,http://edocs.tu-berlin.de/diss/2002/rabus_dominik.htm, Der Andere Verlag ISBN 3-89959-022-8.

M. Schubert, Power-aware spatial multi-plexing with unilateral antenna coopera-tion, TU Berlin, Fakultät IV (Elektrotechnikund Informatik), Prof. H. Boche.

K. Seifert, Evaluation multimodaler Compu-ter-Systeme in frühen Entwicklungsphasen.Ein empirischer Ansatz zur Ableitung vonGestaltungshinweisen für multimodaleComputer-Systeme (Evaluation of multi-modal computer systems in early phasesof development - An empirical approachto derive evidence for the design of multi-modal computer systems), TU Berlin, Fakul-tät V (Verkehrs- und Maschinensysteme),Prof. K.-P. Timpe, Prof. L. Blessing.

DIPLOMA THESES

F. Boczianowski, Monolithisch 40 GHz-modengekoppelte Laser für die OTDM-Nachrichtenübertragung (Monolithicallyintegrated 40 GHz-mode-locked laser forOTDM-communications), TU Berlin, Fakul-tät II (Mathematik und Naturwissenschaften),Optisches Institut. Supervisors at HHI: B. Hüttl, R. Kaiser.

S. Brahma, Untersuchungen zum Phasen-rauschen einer optischen Pulsquelle(Investigations on phase noise of an opti-cal pulse source), TU Berlin, Fakultät IV(Elektrotechnik und Informatik), Institut f.Hochfrequenztechnik. Supervisor at HHI:H. G. Weber.

G. Bramann, Measurements and analysis of

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next-generation optical fibre transmissionsections with particular reference to dis-persion management, HHI jointly withUniversity of Central England. Supervisor atHHI: E.-J. Bachus.

D. Hildebrand, Untersuchung von hybridenVerfahren zur Videocodierung (Explorationof hybrid video coding methods), TFH Berlin, Fachbereich II (Mathematik).Supervisor at HHI: D. Marpe.

A. Jacob, Optimierung der Faser-Chip-Kopplung am Laserschweißplatz. Schwin-gungsunterstützte Minimierung der Haft-reibung bei der Justage im Sub-Mikrome-terbereich (Optimizing the fiber-chip-coupling at the laser welding machine.Vibration backed minimization of the static friction with adjustments in the sub-micron-area), FHTW Berlin, Mikrosystem-technik. Supervisor at HHI: Th. Rosin.

D. Kossack, Untersuchungen zum Einflußvon Korrelationseigenschaften der Spreiz-sequenzen in CDMA-basierten Mobilfunk-systemen mit Mehrnutzerempfängern(Investigation of the influence of correla-tion properties of spreading sequences inCDMA-based mobile communications sys-tems with multiuser receivers), TU Berlin,Fakultät IV (Elektrotechnik und Informatik),Insitut für Telekommunikationssysteme.Supervisor at HHI: S. Stanczak.

H. Louchet, Control modulation techniquefor optical performance monitoring inWDM networks with phase modulatedclient signals, TU Berlin, Fakultät IV (Elektro-technik und Informatik), Institut f. Hochfre-quenztechnik. Supervisor at HHI: M. Rohde.

M. Malach, Dynamisches Verhalten derRaman-Verstärkung (Dynamic propertiesof the Raman amplification in case ofWDM transmission), TU Berlin, Fakultät IV(Elektrotechnik und Informatik), Institut f.Hochfrequenztechnik. Supervisor at HHI: E. Schulze.

K. Mertens, Untersuchung neuer Übertra-gungsverfahren in dynamischen Glasfaser-netzen mit Wellenlängen-Multiplextech-nik (Investigation of novel transmissionschemes in dynamical fibre WDM net-works), TFH Berlin, Fachbereich VII (Elektro-technik und Feinwerktechnik). Supervisors atHHI: M. Rohde, E.-J. Bachus, C. Caspar.

F. Neumann, Automatische Detektion derAugen in 2D Videosequenzen für multi-modale Mensch-Computer-Interaktion(Automatique eye detection in 2D videosequences for multi modal human-com-puter-interaction), TU Berlin, Fakultät IV(Elektrotechnik und Informatik) Institut f.Technische Informatik und Mikroelektronik.Supervisor at HHI: J. Liu.

S. Ritter, Experimentelle Charakterisierungvon 1,55 µm-Fabry-Perot-Halbleiterlasernmit integrierten sättigbaren Absorber, fürAnwendungen in hochratigen Pulsquellen(Experimental characterisation of1,55 µm-Fabry-Perot-semiconductor laserwith integrated saturable absorber for ap-plications in high bit-rate pulse sources),TFH Berlin, Fachbereich II (Mathematik-Physik-Chemie) Fachgruppe Physik:Laseranwendungen und Optoelektronik.Supervisors at HHI: B. Hüttl, R. Kaiser.

D. Schröder, J. Roeske, Bildqualität von analog und digital produzierten Bildfol-gen (Image quality resulting from analogvs. digital cameras), FU Berlin, FB 12(Erziehungswissenschaften). Supervisor atHHI: J. Faber.

GRADUATE THESES

P. Voigt, Entwicklung eines steuerbarenVideoservers zur Übertragung von MPEG-4Echtzeitvideoströmen (Implementation ofa controllable server for real-time MPEG-4video streaming), TU Berlin, Fakultät IV(Elektrotechnik und Informatik) Institut fürTelekommunikationssysteme. Supervisor atHHI: K. Müller.

T. Trietz, Aufbau eines Meßmikroskops(Building a microscop for measurements),FHTW Berlin, Mikrosystemtechnik. Supervisorat HHI: Th. Rosin.

S. Wendler, Untersuchen von Schweißpara-metern für das Dichtschweißen von OEICsmittels Laserschweißen (Investigation ofparameters for hermetic sealing of OEICsby means of laser welding), FHTW Berlin,Nachrichtentechnik. Supervisor at HHI: Th. Rosin.

L. Molle, Untersuchung zum Dispersions-management in hochratigen Wellenlän-

genmultiplex-Glasfasernetzen (Investi-gation on dispersion management forhigh bitrate WDM networks), TU Berlin,Fakultät IV (Elektrotechnik und Informatik),Institut für Telekommunikationssysteme.Supervisors at HHI: E.-J. Bachus, R. Freund.

H. Nguyen, Analyse von Multiple InputMultiple Output Funkkanälen anhand vonMessungen (Analysis of MIMO radio chan-nels based on Measurements), TU Berlin,Fakultät IV (Elektrotechnik und Informatik)Institut für Telekommunikationssysteme.Supervisor at HHI: V. Pohl.

ORAL PRESENTATIONS

K.-D. Langer, KomNet – On the way to thebroadband Internet, DFN-Workshop“Optische Netze”, Berlin, 8./9.1.2002.

H. Boche, M. Schubert, Joint writing-on-dirty-paper precoding and downlinkbeamforming achieve the ultimate capaci-ty, Universität Bremen, 5.2.2002.

V. Jungnickel, V. Pohl, T. Haustein und C. v. Helmolt, Erste Ergebnisse zu breit-bandigen MIMO Kanalmessungen bei 5.2 GHz, Space-Time SignalprocessingWorkshop, Institut für Telekommunikationund Hochfrequenztechnik (ITH), UniversitätBremen, 5.2.2002.

H. Boche, E. Jorswieck, Kapazität für MIMO-Systeme mit Kovarianzfeedback (invited),Universität Bremen, 6.2.2002.

H. Boche, M. Schubert, Space-Time-Signal-processing für die Mobilkommunikation(invited), Universität Bremen, 6.2.2002.

K. Schenke, Mixed Reality, Interaktion mitvirtuellen Objekten, CeBIT 2002 Future Talk,Hannover, 16.3.2002.

E. Jorswieck and H. Boche, MIMO Kapazitätbei ungenauer Kanalkenntnis am Sender,Space-Time-Signalprocessing Workshop, HHIBerlin, 11.4.2002.

E. Jorswieck and H. Boche, On the Schur-concavity of the ergodic and outage ca-pacity with respect to correlation in multi-antenna systems with no CSI at the trans-mitter, Space-Time-SignalprocessingWorkshop, HHI Berlin, 11.4.2002.

K. Schenke, Autostereoskopische Displays,Grundlagen, Realisierungskonzepte,Anwendungen, Best Practice-SeminarreiheProf. Krömker, Fraunhofer AGC (Anwen-dungszentrum Computergraphik in Chemieund Pharmazie), Frankfurt, 16.5.2002.

T. Wiegand, H.26L Video Transmisson in3G Wireless Environments, Intern. Conf. onThird Generation Wireless and Beyond, SanFrancisco (CA, USA), May 2002.

V. Jungnickel, Zum Einfluß verschiedenerAntennengeometrien auf die MIMO-Kapazität (indoor/outdoor), Space-TimeSignalprocessing Workshop, Ilmenau, 13.-14.6.2002.

V. Pohl, Die Struktur von linearen Entzerr-filtern für frequenzselektive MIMO Kanäle,Space-Time Signalprocessing Workshop,Ilmenau, 13.-14.6.2002.

K. Müller, Semantische Inhaltsbeschreibungdurch MPEG-7, Internationales SymposiumVernetzte Fernsehproduktion Köln, June2002.

D. Marpe, Trends and Emerging Standardsin Video Coding, Invited Talk (in German) at19. Heidelberger Bildverarbeitungsforum:Bildkompression und Bildkodierung; Akade-mie für Weiterbildung an den UniversitätenHeidelberg und Mannheim e. V., Fachhoch-schule Aschaffenburg, 9.7.2002.

R. Schäfer, Video based Services forDAB/DVB-T and UMTS Using NovelCompression Methods, Workshop of theRegTP, Mainz (DE), 10.7.2002.

K. Biermann, D. Nickel, K. Reimann, M. Woerner, T. Elsaesser, H. Künzel,Ultrafast nonlinear optical response atwavelengths around 1.55 mm of in low-temperature-grown GaInAs/AlInAs quan-tum wells (poster), 26th Intern. Conf. on thePhysics of Semiconductor, Edinburgh (GB),29.7.-2.8.2002.

R. Schäfer, H.26L developments, EBUSpecialised Meeting on Audio/Video CodingTechnologies, Geneva (CH), 5./6.9.2002.

R. Schäfer, JVT/H.26L Video Coding, LocalEvent from the FKTG, Sender Freies Berlin,10.9.2002.

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E. Jorswieck and H. Boche, Sum CapacityOptimization of the MIMO Gaussian MAC(invited), Universität Bremen, 10.-11.9.2002.

A. Sezgin, Joint decoding and channel esti-mation for low-complexity STC (invited),Universität Bremen, 10.-11.9.2002.

A. Smolic, The Emerging H.264/AVC VideoCoding Standard, Workshop on UpcomingVideo Coding Standards, Vrije UniversiteitBrussel (VUB), Brussels (BE), 30.9.2002.

T. Wiegand, Context-Based AdaptiveBinary Arithmetic Coding in JVT/H.26L,International Conference on ImageProcessing, Rochester (NY, USA), Sept. 2002.

T. Wiegand, Performance Comparison ofVideo Coding Standards using LagrangianCoder Control, International Conference onImage Processing, Rochester (NY, USA),Sept. 2002.

T. Wiegand, The Emerging H.264/AVCVideo Coding Standard, IBM, Yorktown(NY, USA), Sept. 2002.

T. Wiegand, Gary J. Sullivan (Microsoft,USA), The H.264/AVC Video CodingStandard, Tutorial at the InternationalConference on Image Processing, Rochester(NY, USA), Sept. 2002.

T. Wiegand, H.264/AVC for MultimediaStreaming, International Streaming MediaAlliance / Philips, Eindhoven (NL) / USA,Sept. 2002.

M. Rohde, Prüfmodulationsverfahren zum“Performance Monitoring” in 10 Gb/sWDM-Systemen, DFG-Kolloquium,München, 7./8.10.2002.

E. Schulze, Dynamisches Verhalten inWDM-Systemen: Vergleich von verteilterRaman-Verstär-kung und EDFA-Ketten,DFG-Kolloquium, München, 7./8.10.2002.

M. Seimetz, Vorteile und Realisierbarkeitdes optischen Homodynempfangs in zu-künftigen WDM-Netzen, DFG-Kolloquium,München, 7./8.10.2002.

B. Hüttl, Experimental characterization ofmonolithic 40GHz mode-locked lasers onGaInAsP/InP, Seminarvortrag im Rahmendes Forschungsseminars “Mathematische

Modelle der Photonik, Minisymposium überMode Locked Laser”, Veranstalter: WIAS, HU-Berlin, 24.10.2002.

A. Nesterov, U. Troppenz, Laser, Filter undWellenlängenkonverter auf der Basis aktiv-er GaInAsP Mikroringresonatoren; Ziel,Modelle, Zwischenergebnisse, Seminar-vortrag im Rahmen des Forschungsseminars“Mathematische Modelle der Photonik”,Veranstalter: WIAS, HU-Berlin, 31.10.2002.

H. H. Yao, Polymer waveguide devices forDWDM applications (invited), KwangjuInstitute of Science and Technology,Kwangju (KOR), 1.11.2002.

H. H. Yao, Polymer waveguide devices forDWDM applications (invited), ElectronicTelecommunications Research Institute (ETRI)and ZenPhotonics, Daejon (KOR), 2.11.2002.

R. Schäfer, Fundamentals of DVB and DVB-T,Seminar on Digital TV of Freie Universitätand Humboldt-Universität, HumboldtUniversity Berlin, 4.11.2002.

M. Seimetz, Vorteile und Realisierbarkeitdes optischen Homodynempfangs inzukünftigen WDM-Netzen, TU Berlin,Seminar zur optischen Nachrichtentechnik,22.11.2002.

E. Schulze, Dynamics of Raman AmplifiedWDM Links, Workshop on optical WDM-transmission and networks, jointly withCOM, HHI, T-Systems, TZ Berlin, 25.11.2002.

M. Seimetz, Homodyne Detection in FutureWDM-Networks, Promises & Problems,Workshop on optical WDM-transmission andnetworks, jointly with COM, HHI, T-Systems,TZ Berlin, 25.11.2002.

E. Jorswieck and A. Sezgin, An iterative SignalProcessing Algorithm (ISIP) for MIMO sys-tems, Space-Time-Signalprocessing Work-shop, Universität Ulm, Nov. 2002.

S. Golka, Design und Herstellung photonis-cher Kristalle in InP, Seminarvortrag imRahmen der Veranstaltung “PhotonischeKristalle – Modellierung, Simulation undTechnologie”, Konrad-Zuse-Zentrum (ZIB),Berlin, 2.12.2002.

S. Gouraud, D. Franke, P. Harde, A. Paraskevopoulos, Iron doping behaviour

in InP grown by LP-MOVPE in the pres-ence of Tertiarybutylchloride, DGKKWorkshop, Magdeburg (DE), 12.12.2002.

K. Biermann, J. Böttcher, H. Künzel, MBEWachstum von GaInAs/AlAsSb MQWs aufInP für “kurzwellige” Intersubband-Über-gänge, DGKK Workshop, Magdeburg (D),13.12.2002.

J. Faber, Probleme und nicht verbaleVerfahren zur Erfassung von Stimmungen,Gefühlen und Bedürfnissen, VµE-Arbeits-kreis Perceptual User Interface, Erlangen,18.12.2002.

C. Fehn, P. Kauff, M. Op de Beeck (Philips,NL), F. Ernst (Philips, NL), W. Ijsselsteijn(TU/e, NL), M. Pollefeys (KU Leuven, BE), L. Van Gool (KU Leuven, BE), E. Ofek (3DVSystems, IL), I. Sexton (De MontfortUniversity, GB), IST Project ATTEST – AnEvolutionary and Optimised Approach on3D-TV, Invited Talk at Picture CodingSymposion Japan (PCSJ 2002), Shizuoka (JP),Dec. 2002.

LECTURES

H.-G. Bach, Grundlagen der optoelektroni-schen Halbleiterbauelemente, TU Berlin

H.-G. Bach, Messverfahren für Halbleiterbau-elemente, TU Berlin

E.-J. Bachus, Photonische Kommunikations-netze, TU Berlin

H. Boche, Digitale Mobilkommunikation I,TU Berlin

H. Boche, Space-Time-Signalprocessing fürdie Mobilkommunikation, TU Berlin

H. Boche, Mehrnutzer-Informationstheorie,TU Berlin

H. Boche, TU-Kolloquium “Digitale Mobil-kommunikation” jointly with Prof. P. Nolland Prof. A. Wolisz, TU Berlin

P. Eisert, Visualisierung, Codierung undÜbertragung virtueller 3D Welten, TU Berlin

G. Heising, Digitale Videotechnik, TFH Berlin

L. Ihlenburg, Entwicklungstendenzen derMultimediakommunikation, TU Berlin

V. Jungnickel, Übertragungsverfahren, TU Berlin

V. Jungnickel, Adaptive Übertragungssysteme,TU Berlin

I. Keller, Klassifikation in der Nachrichten-technik, TU Berlin

A. Kortke, Praktikum Digitale Mobilkommu-nikation I, TU Berlin

A. Kortke, H. Boche, Praktikum Space-Time-Signalprocessing, TU Berlin

B. Kuhlow, Einführung in die Photonik, TU Berlin

A. Paraskevopoulos, Halbleitertechnologie für die Integration in der Optoelektronik, TU Berlin

M. Rohde, Optische Nachrichtentechnik,TFH Berlin

O. Schreer, Stereobildverarbeitung in derVideokommunikation, TU Berlin

P. Stammnitz, Einführung in Kanalcodie-rungsverfahren, TU Berlin

H. G. Weber, Grundlagen und Anwendungender linearen und nichtlinearen Faseroptik, TU Berlin

T. Wiegand, Digitale Bildkommunikation, TU Berlin

WORKSHOPS ORGANISED

Nokia Leading Science 4 Program, HHIBerlin, January

Final review of national R&D ProgrammeKomNet, HHI Berlin, April

ITG-FKTG Workshop Media Streaming, HHIBerlin, June

IST Programme: BUSMAN, 2nd ManagingCommittee Meeting, HHI Berlin, July

2. open TransiNet Workshop, TransiNet:

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Innovative Transportnetze für das BreitbandInternet, HHI Berlin, October.

ITG-Workshop, Breitbandige Zugangsnetzeund Integrierte Inhausnetze, HHI Berlin,October.

Mensch-Maschine-Schnittstellen: AmbientIntelligence, Workshop organized jointly withFhG µE-Verbund, HHI Berlin, October

CONTRIBUTIONS TO EXHIBITIONS

CeBIT 2002, Hanover, March:Mixed Reality interaction with virtual objectsDigital cinema / Digital projection systems

FKTG 2002, Zurich (CH), June:Interactive streaming of high-resolutionpanoramic viewsH26L streamingMulti projection system

Internationale Frachttage der LufthansaCargo AG, Lufthansa BildungszentrumSeeheim, June:Mixed Reality interaction with virtual objects

ITG/FKTG – Workshop Media – Streaming,Berlin, June:ISMA-compatible and platform independentstreaming solutionsMPEG-4 Encoder-ASIC for mobile streaming-applicationsBMS-ProjectInteractive streaming of high resolutionpanoramic viewsOMSA-ProjectH.26L Codec

IBC 2002, Amsterdam (NL), September:Immersive projection system (Multi-projec-tion)H26L streamingHiCon32 video converterMPEG-4 video codec ASIC for mobile appli-cationsInteractive streaming of high resolutionpanoramic views

COMMITTEE ACTIVITIES

Standardisation Committees

DIN

DVB Technical Module: Member

IPC, Committee 5-20, Subcommittee 5-25:Member

ISO/MPEG

ITU-T, SG 16, Associated Rapporteur

JVT, Co-chair

Research Program Committees

COST 266, Progress of PhotonicInfrastructure towards the IT-Age: MemberMCM

COST 267, Semiconductor devices for signalprocessing WG2: Chairman

COST 268, Management Committee:Member (deputy)

IST (Inform. Society Technologies): Evaluator

Strategische Plattform Informationstechnik:Member

Conference and Workshop ProgramCommittees

CLEO Technical Program Committee:Member

10th Dortmunder Fernsehseminar: ProgramCommittee

ECOC Technical Program Committee:Member

11th European Conference on IntegratedOptics (ECIO '03), 2003, Prague (CZ):Program Committee Member

European Leica Beamwriter Users Meeting:Chairman

Human Factors in Telecommunications:Permanent Steering Committee

IC MOVPE-XI, Berlin 2002: ProgramCommittee Member

14th Intern. Conf. on InP & RelatedCompounds (IPRM '02), Stockholm: ProgramChair

International Picture Coding Symposium:Steering and Program Committee Member

International Zurich Seminar (IZS 2002):Program Committee

Net & Home – Congress, Technical ProgramCommittee: Member

Packet Video Workshop: Program Committee

Potsdamer Film Kolleg: Program Committee

SPIE Conf. on Design an Fabrication of PlanarOptical Waveguide Devices and Materials,San Diego (USA): Program CommitteeMember

Technisch-Wissenschaftliches Forum IFA '03

VIProm Com '02: Program Committee

VTC Spring 2003 TPC: Member

Editorial Boards

IEEE ICME Track Chair

Institute of Physics (GB)/SemiconductorScience and Technology: Referee

Springer Verlag Berlin, Heidelberg, Series“Photonics”: Co-Editor

Other Committees

Aspen Institut Berlin: Member

Competence Center for the Application ofNanostructures in Optoelectronics (NanOp):Member of Executive Board

FKTG, Urtel-Preis-Komitee: Curatorship

11th International Conference on Metal-Organic Vapour Phase Epitaxy (IC MOVPEXI), Berlin: Public Relations

ITG, FA 3.1 Fernsehtechnik und elektronischeMedien: Chairman

ITG, FG 3.1.2 Digitale Bildcodierung:Chairman

ITG FG 5.2.5 Access- und Inhouse-Netze:Member

ITG, FA 5.3 Optische Nachrichtentechnik:Member

ITG, FG 5.3.1 Modellierung photonischerKomponenten und Systeme: CommitteeMember

ITG, FG 5.3.2 Photonische Integrations- undAufbautechnik: Chairman

ITG, FG 5.3.3 Photonische Netze: Member

ITG, FG 5.4.1 Optische Polymerfasern:Member

LMTB – Laser und Medizin-TechnologieGmbH, Berlin: Advisory Committee

Münchner Kreis, Supranational Associationfor Communications Research: ResearchCommittee

OPTEC BB, Berlin: Member

TSB-Technologiestiftung InnovationszentrumBerlin: Board of Curators

VDI optische Technologien: Advisory Board

EXCHANGE PROGRAM

Scientists Visiting HHI

K. Biermann, Max-Born Institut, Berlin, financed by MBI, for three months

R. Böhnke, Universität Bremen, financed byUniversität Bremen, for two months

B. Cai, Tohoku University, Sendai (J), financed by Tohoku University, for threemonths

S. Dressler, Humboldt Universität zu Berlin,financed by HUB, for one year

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R. Freund, Fa. VPI, Berlin, financed by VPI, forten months

F. Futami, Fujitsu Laboratories Ltd.,Nakahara-ku, Kawasaki (J), financed byFujitsu, for six weeks

S. Gouraud, Alcatel CIT/OPTO+, Marcoussis(F), financed by Alcatel Paris, for one year

V. Haisler, Institute of Semiconductors,Novosibirsk (RUS), financed by Institute ofSemiconductors, for nine months

Y. Horita, Toyama University, Toyama (J), financed by Toyama University, for threemonths

T. Ido, Hitachi Ltd., Central ResearchLaboratory, Tokyo (J), financed by HitachiLtd., for seven months

I. Koichi, Kanazawa University (J), financedby the Japanese Government, for one month

A. Kortke, TU Berlin, financed by TUB, foreight months

V. Kravcenko, TU Berlin, financed by TUBerlin, for one year

M. Lämmlin, TU Berlin, financed by TUB, forfive months

N. T. Quang Le, Technical University ofDenmark, Lyngby (DK), financed by TU ofDenmark, for three months

Ei Ei Minn, Ministry of Sience andTechnology, Yagon (MM), financed byDAAD, for six months

M. Mrak, University of Zagreb (HR), financedby DAAD, for six months

T. Oechtering, TU Berlin, financed by TUB,for three months

N. Sabelfeld, MergeOptics GmbH, Berlin, financed by MergeOptics GmbH, for twomonths

L. Schares, ETH-Zürich, Zürich, (CH), financed by ETH-Zürich, for two weeks

T. Strohmer, University of California,Stanford University, Davis, (CA, USA), financed by HHI, for two weeks

S. Watanabe, Fujitsu Laboratories Ltd.,Nakahara-ku, Kawasaki (J), financed byFujitsu, for five weeks

HHI Scientists Visiting Foreign Institutes

A. Festag, TU Berlin, financed by HHI, for oneyear

A. Sezgin, University Bremen, financed byHHI, for two months, and Arizona StateUniversity (USA), financed by HHI, for threeweeks

COOPERATIONS

Industry

Acterna, Eningen

A.C.T. Kern, Donaueschingen

Actryon GmbH, Berlin

adaptif Photonics GmbH, Hamburg-Harburg

Aifotec GmbH, München

Alcatel SEL, Stuttgart

Alcatel, Paris

Alpha Baumanagement, Aachen

ATIP GmbH, Frankfurt/M.

ASL – Applied Science Laboratories, Bedford,(MA, USA)

AVRIO Technologies Europe GmbH, Berlin

AXON Photonics, Livermore (CA, USA)

Bayerischer Rundfunk, München

BBC, London

Bertelsmann, Gütersloh

Blaupunkt-Werke GmbH, Hildesheim

British Telecom, Martelsham Heath, Corning(GB)

Btexact Technologies, London (GB)

Canto, Berlin

Carl Zeiss, Jena, Oberkochen

com center, Kopenhagen

CRL Opto Ltd., Hayes (GB)

DaimlerChrysler, Ulm

das werk, München

Dr. Detlef Rose Fotomasken Mikroelektronik,Bergisch Gladbach

D-Research Digital Media Systems GmbH,Berlin

EPIGAP Optoelektronik GmbH, Berlin

Ericsson Eurolab, Aachen

Fiber Core, Jena

framepool München

Fresnel Optics GmbH, Apolda

Fujitsu Laboratories Ltd., Wakamiya (JP),London

GWS Photonics Israel Ltd., Ramat Gan (IL)

Hitachi Central Research Laboratory, Tokyo,Cambridge (GB)

HoloEye GmbH, Berlin

Infineon Technologies, Berlin, Regensburg,München

ISIS Optronics, Mannheim

IVU Traffic Technologies, Berlin

JDS Uniphase, Eindhoven (NL)

Kerpenwerke, Stolberg

Laser Components GmbH, Olching

Laytec GmbH, Berlin

Leybold Optics Dresden GmbH, Dresden

Loewe-Opta GmbH, Kronach

Lucent Technologies, Nürnberg, Holmdel(NJ, USA)

Lumics GmbH, Berlin

MAZ level one GmbH, Hamburg-Harburg

Medav Digitale Signalverarbeitung GmbH,Uttenreuth

Medienanstalt Sachsen-Anhalt

MergeOptics GmbH, Berlin

Mikrom, Berlin

moove, Leverkusen

Motorola U.K. Research Lab, Basingstoke(GB)

NTT – Nippon Telegraph and TelephoneCorporation, Tokyo

Nokia, Espoo (SF)

Optibase, Herzliya (IL)

Opto+, Paris

OptoSpeed SA, Darmstadt, Zürich

Philips BV, Eindhoven (NL)

Quantum Devices Inc. (QDI), Yorba Linda,(CA, USA), Berlin

Robert Bosch GmbH, Hildesheim, Stuttgart

sci-worx, Hannover

Sentech Instruments GmbH, Berlin

Siemens AG, Berlin, München, Regensburg

Tecsi, Paris

Telefónica, Madrid

Telenor, Oslo

Teracom AB, Stockholm

Tesat-Spacecom GmbH & Co. KG, Backnang

Thales Research & Technology France, Orsay(FR)

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TNO Physics and Electronics Laboratory, DenHaag (NL)

TOPTICA Photonics AG, München

T-Systems Nova, Berlin, Darmstadt

u2t Photonics AG, Berlin

Vcon Telecommunications Ltd. (IL)

Virtual Photonics Inc., Berlin, Melbourne,Freehold (USA)

Vodafone Ltd., Newbury (GB)

Xignal Technologies AG, München

2SK Media Technologies, Berlin

Universities and Institutes

Brunel University, Uxbridge (GB)

Denmark Technical University, Kopenhagen

DFN-Verein, Berlin

ENST Paris

ETH Zürich

European Broadcasting Union, Genf

Fachhochschule für Wirtschaft und Technik(FHTW) Berlin

Ferdinand-Braun-Institut, Berlin

FhG Einrichtung für Systeme derKommunikationstechnik, München

FhG Institut für Biomedizinische Technik

FhG Institut für Integrierte Schaltungen,Erlangen

FhG Institut für Medienkommunikation (FhG-FOKUS), Berlin

FhG Institut für MikroelektronischeSchaltungen und Systeme, Duisburg

FhG Institut für Zuverlässigkeit undMikrointegration, Berlin und Teltow

FhG/IGD, Darmstadt

FhG Institut für AngewandteInformationstechnik, St. Augustin

FhG Institut Siliziumtechnologie, Itzehoe

Freie Universität Berlin, Fachbereich Physik

Heriot-Watt University, Edinburgh (GB)

Hochschule Harz, Wernigerode

Humboldt-Universität zu Berlin

IAF Freiburg

INRIA, Paris

Institut d'Optique, Paris

Institut für Rundfunktechnik, München

Ioffe-Institut, St. Petersburg

IRISA, Rennes (FR)

Konrad-Zuse-Institut, Berlin

Max-Born-Institut, Berlin

MPI Halle

Optotransmitter-Umweltschutz-Technologiee.V., Berlin

Paul-Drude-Institut, Berlin

Queen Mary Westminster College, London

Stanford University (CA, USA)

Technische Fachhochschule Berlin

Tokyo University

TU Berlin

TU Braunschweig

TU Darmstadt

TU Delft (NL)

TU Denmark, Lyngby

TU Hamburg-Harburg

TU Ilmenau

TU München

Universidad Politecnica Valencia (E)

Universität Aachen

Universität Bremen

Universität Dortmund

Universität Duisburg

Universität Karlsruhe

Universität Rostock

Universität Stuttgart

University of Torino (IT)

Universität Würzburg

University of Essex (GB)

University of Gent, IMEC (BE)

University of Illinois at Chicago (USA)

University of North Carolina, Chappel Hill(USA)

Weierstraß-Institut für Angewandte Analysisund Stochastik (WIAS), Berlin

Zentral- und Landesbibliothek, Berlin

Technology Collaboration Networks

NanOp, Berlin

Optec BB, Berlin

Telscom (CH)

START UP COMPANIES

DSPecialists GmbH, BerlinDSPecialists develops systems and tools fordigital signal processing using digital signalprocessors (DSP). Its focus is to provide plat-forms in software and hardware for cus-tomers in various branches, such as audio,video, telecom and measurement/control.DSPecialists sells its products and provides

different kinds of services, such as technicaltraining and application development.

Virtual Photonics Incorporated (VPI)VPI Virtual Photonics makes design and planning tools for access providers, networkoperators, system integrators and manufac-turers of WDM transmission systems and optical components. Lead customers includeAlcatel, Hitachi, Deutsche Telekom, Lucent,Pirelli, MCI and Sprint. Siemens, Telcordiaand Open Telecommunication are world-wide business partners. VPI employs 150+ technical experts, consul-tants, developers and sales persons. Officesare located in Berlin, Munich (BroadbandAccess), Holmdel, NJ (IP/Optical Network-ing), Australia (Optical Systems) and Minsk(Software Production). Investors includeWeiss, Peck & Greer, Siemens, TechnoVenture Management and DeutscheTelekom.

2SK Media Technologies GbR, Berlin2SK Media Technologies develops and mar-kets software for compression and decom-pression of audio and video signals accordingto the MPEG standards. Its main product isthe MPEG SoftEngine, which currently sup-ports MPEG-1 and MPEG-2. Future products,which will support MPEG-4 and MPEG-7, areunder development.

MikroM, BerlinMikroM develops and designs VLSI compo-nents for image and sound processing andcompression. Its main product is HiPEG+, asingle chip HDTV decoder according to theMain Profile@High Level of MPEG-2. Thischip, which is based on the HiPEG chip pre-viously developed at HHI, contains the videodecoder and the systems demultiplex.

u2t Photonics AG, Berlinu2t Photonics AG was founded in 1998 bythree scientists of HHI and is now recognizedworldwide as a leading-edge supplier for theoptical telecommunications market. U2t de-velops and manufactures innovative opto-electronic components for the highest speedapplications. Flagship is an ultrafast photode-tector with more than 50 GHz bandwidth,capable of handling very high input power.Other products such as photoreceivers andmodulators are especially designed for40 Gbit/s communication systems.In 2001, u2t merged with another HHI spin-off, LKF Advanced Optics GmbH to combine

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their complemetary product portfolios. Formore information please visit www.u2t.de ormail to contact@u2t.de.

Usability Lab am HHI, BerlinThe company supplies Human Factors andUsability support at all phases of the productlife cycle. For all information and communi-cation technology products (services, sys-tems, terminals, user interfaces, etc.) it offersuser requirements analyses (based on empiri-cal studies), design studies with detailed rec-ommendations, evaluation of prototypes andproducts already on the market (by means ofCognitive Walkthroughs, Heuristic Evaluation,and Usability tests with test subjects), andconsultancy in terms of strategic decisions onproduct lines. (www:http://ulab.hhi.de)

MicroShape, BerlinMicroSHAPE (Software and HardwareApplication Engineering) develops softwareand hardware components and tools focus-ing on digital image processing. FurthermoreMicroSHAPE develops complete prototypesystems and peripheral units. Starting atschematic architectures via structure simula-tions and layout designs up to high integrat-

ed FPGA developments, all steps are microaccurately done by this company. The firstproduct will be a digital to analogue inter-face module for HDTV projection systemscompliant to the DVB and ATSC standard.

Perspective Technologies GmbH (PT),BerlinPerspective Technologies GmbH Berlin is a3D display and interaction systems develop-ment and marketing company founded by ateam of scientists of the HHI and experts inthe fields of market research, business strate-gy and innovation management. PerspectiveTechnologies is pioneering the combinationof highest-quality 3D technologies with novel non-intrusive user-interaction systems.As a result, PT’s displays produce stunning 3Deffects without the need of any encumberingviewing aids, such as stereo glasses or head-mounted devices. The proprietary interactiontechnologies are based on the latest resultsin digital image processing and computer vision research. First 3D display products willapply the lenticular lens technology, adaptedto range of target applications, e.g. in med-ical imaging, molecular design and 3D CAD.

FRAUNHOFER-HHI AT A GLANCE

Public Research Institute (Shareholder: Fraunhofer-Gesellschaft zurFörderung der angewandten Forschung e.V.,Munich)Total staff at end of 2002: 274 employees

Areas of Research andDevelopment

Photonic Networks• Design, development and demonstration

of optical communication networks and subsystems (access, metro, and customer networks)

• Investigation and development of WDMand high-speed OTDM techniques forhigh capacity transmission and routing

• Exploration of high speed transmissionperformance of photonic networks

• Development of techniques for networkoperation and maintenance

• Development and fabrication of photonicdevices and integrated circuits (lasers,modulators, switches, optical amplifiers,filters, multiplexers and demultiplexers,signal regenerators, transceivers, receiverfrontends) based on InP, for passive components on SiO2/Si and polymers

• Development of new concepts for carrying IP traffic over WDM optical networks and wireless networks in an efficient manner (TransiNet)

• Switchable network design and testing

Mobile Broadband Systems• Development of space-time-receiver for

the uplink of mobile communication systems

• Design of downlink beamforming for CDMA-based mobile communication systems

• Teletraffic engineering for mobile communication systems

• Development of signal processing algorithms for OFDM/Multicarrier systems

• Development of sequences for CDMA applications and multiuser receiver

• Development of optical indoor transmis-sion networks for broadband WLAN

• Analysation of cooperative systems• MIMO channel measurements and

evaluation• Implementation of MIMO systems• Development of signal processing

algorithms for MIMO systems• Cooperative receiver and transmitter

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Electronic Imaging Technology for Multimedia• 3D image and video processing• Image and video coding• Image and video analysis and synthesis• Multimedia transmission (IP, mobile, DVB)• Hardware, software design and implemen-

tation of multimedia systems (video, audio, graphics), ASIC and IP design

• Immersive reproduction technologies• Multi-view capturing and reproduction

systems• Innovative 3D and mixed-reality displays• Perceptual user interfaces for mobile and

desktop applications• Human-machine interaction• MPEG-7 based image and video retrieval

systems• Mobile services for citizens• Sensing people technologies• Usability engineering

FRAUNHOFER INSTITUTE FORTELECOMMUNICATIONS,HEINRICH-HERTZ-INSTITUT

Einsteinufer 37, 10587 BerlinGermanyPhone: +49 (0)30 3 10 02-0Fax: +49 (0)30 3 10 02-213Email: info@hhi.fraunhofer.dehttp://www.hhi.fraunhofer.de

Executive Director:Prof. Dr. Joachim Hesse

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