The SARDANA FTTH Network

(SARDANA: Scalable Advanced Ring-based passive Dense Access Network Architecture)

SARDANA Consortium Partner representatives: Coordinator: Josep Prat, UPC (jprat@tsc.upc.edu) Risto Soila, Tellabs (risto.soila@tellabs.com) Spiros Spirou , Intracom Telecom (spis@intracom.gr) Philippe Chanclou, Orange Labs (philippe.chanclou@orange-ftgroup.com) Antonio Teixeia, IT (teixeira@ua.pt) Giorgio M. Tosi Beleffi, ISCOM (giorgio.tosibeleffi@sviluppoeconomico.gov.it) Ioannis Tomkos, AIT (itom@ait.edu.gr)

November 30, 2010

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I. Situation/Market Need for SARDANA

Internet usage has accelerated dramatically in recent years, pressing network operators to seek innovations that will enable them to profitably meet consumers’ and businesses’ demand for high-speed Internet bandwidth. All evidence indicates that this trend will not only continue, but most likely will grow:

“Internet traffic growth will continue to rise over the next five years, hitting a whopping 767 exabytes by 2014, according to the latest Visual Networking Index (VNI) forecast from Cisco,” in line with a June 2, 2010 article on EnterpriseNetworkingPlanet.com by Sean Michael Kerner. Although file-sharing and peer-to-peer (P2P) networking are still the largest drivers of consumer bandwidth usage (46 percent and 39 percent respectively, in 2009), the VNI forecast indicates they are being eclipsed by video and other types of content. “Internet video traffic will surpass peer-to-peer traffic by the end of the year (2010), marking the first time that P2P is not the largest Internet traffic type," says Doug Webster, a senior telecom-equipment marketing executive quoted in Kerner’s article. By 2014, the forecast says, 91 percent of Internet traffic will be video, and consumers’ share of global IP traffic will rise from 79 percent to 87 percent.

High-speed Internet connections, which just a few years ago seemed novel to many consumers, are now the norm in developed countries, and have been getting faster year by year. The VNI report notes that “in 2010, 4.4 megabits per second (Mbps) is the average global residential Internet connection download speed. In contrast, back in 2000, consumers were averaging only 127 kilobits per second (Kbps).”

All facts above: http://www.enterprisenetworkingplanet.com/news/article.php/3885571/Global-Networking-Bandwidth-Demand-Starts-to-Slow.htm

As Allard Van der Horst explains in his April 1, 2010 article on Lightwave.com, the tsunami of online-video usage presents special challenges for network operators.

The streaming nature of video means that the bandwidth demand per customer will be much more constant. Currently an access network can offer 32 customers a 100-Mbps Ethernet service using a 1-Gbps access network speed [because of] the statistical nature of the bandwidth requirements of the customers: not everybody needs the full 100 Mbps at the same time.

Video, however, changes this, as people usually watch TV/video in the evening, say between 8 PM and 10 PM. The video data stream is also near constant. This means that telcos will not be able to share a single bandwidth pipe among as many customers as they are used to, and more overall bandwidth will need to be provided to service the same number of users.

Source: http://www.lightwaveonline.com/about-us/lightwave-current-issue/Technology-to-the-rescue-of-next-generation-10G-PON-networks.html

Wireless devices already are a major consumer of bandwidth, and are poised to become the largest. But even as wireless companies have erected tens of thousands of new towers a year for the last several years, they have relied on copper T1/E1 circuits to connect to wired phone networks.1 They have needed these new sites not only to serve their fast-growing subscriber bases, but also to meet users’ accelerating demand for bandwidth, as mobile video, social gaming, and thousands of specialized apps flood the airwaves. Wireless data consumption this year is estimated at 130,000 TB (terabytes) per month, and projected to reach 990,000 TB per

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month by 2014.2 In its “2010 Worldwide Bandwidth Demand” report, RCRWireless.com notes, “We expect massive growth in bandwidth demand, with the developing markets showing much faster growth than the developed markets.”

Trying to meet wireless carriers’ burgeoning backhaul needs with legacy copper connections, however, is just one challenge facing wired networks in this case. Maintaining their backhaul revenue is another. Wireless carriers who use mostly legacy transport protocols such as PDH, ATM over PDH, or SONET/SDH for their backhaul have seen their service charges per connection rise significantly more in recent years than those using primarily packet technologies such as PON or Ethernet.3 Increasingly, these carriers will seek wired-network partners who offer the savings and speed of a passive optical network (PON). More and more wireless operators also are looking to close gaps in their coverage areas—and do so economically—by connecting to the same radio access network (RAN) towers that other wireless carriers use. Where a few years ago most cellular towers handled only one or two operators’ traffic, today it’s common for them to host three or more,1 increasing the burden on their legacy infrastructure.

II. GPON Standardization Efforts—and Implementation Challenges

For the past few years, two leading telecom-industry groups, FSAN/ITU and IEEE, have worked to address these bandwidth-demand issues by developing standards for the architecture and deployment of next-generation, 10-gigabit passive optical networks (NG-PONs). Many of these initiatives have focused on standardizing a particular aspect of NG-PONs. For example:

Bit-rate increases have been the subject of FSAN’s XG-PON1 (10G/2.5G) standard and the IEEE 802.3av Task Force

Network-reach extension has been addressed by IEEE’s GPON TX/RX project and by the ITU-G.984.6 Mid-span Extender standard.

Number of channels and services delivered on a PON (via wavelength-division multiplexing, WDM) was the focus of the ITU-G.984.5 standard.

While each of these standards and projects serves the cause of bringing NG-PON closer to real-world rollout, the number and complexity of them has made implementation of NG-PON challenging for wired networks. Add to this the problem of “backwards compatibility” for NG-PON, as explained by Allard van der Horst in his April 2010 article on Lightwave.com:

Next-generation PONs are expected to be implemented as upgrades to the existing PONs, and will be run over the same fiber plant. This means that, since the losses in the fiber plant will remain the same, the 10G PONs will require at least the same overall power budget (difference between transmit power and receiver sensitivity).

In addition, there are issues of cost and performance with optical transmitters, as van der Horst notes:

When choosing a high-powered laser a trade-off must be made. Directly modulated distributed feedback (DM-DFB or DML) lasers are lower cost than externally modulated lasers (EMLs) and have a higher output power. However, DMLs also have a higher line-width (broader spectrum) than EMLs, which results in higher CD over standard singlemode fiber. This dispersion results in a path penalty, even over the short fibre lengths present in a legacy PON (20 km).

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III. SARDANA: An Innovative Solution Ideal for GPON Implementation

Faced with not only booming demand for bandwidth, but increasingly for bandwidth which is nearly constant (to support video), and with consumers and businesses “trained” to expect ever faster connection speeds, and with accelerating wireless-data traffic pushing backhaul lines closer to their maximum capacity, broadband-network operators need a solution to help them achieve the optimal combination of capacity, speed, scalability, density, resilience, and of course, cost reductions in running their networks. The solution also will need to help carriers accomplish all this while meeting the FSAN/ITU standards for 10-gigabit GPON. That’s what the SARDANA consortium, set out to do in 2008, focusing its goals on “three M’s”:

Maximize capacity to 10 gigabits per second for 32 channels per PON port, and network reach to 100 kilometers, serving up to 1,024 end users per fiber ring.

Minimize infrastructure cost: number of fibers per cable, number of cabinets, etc.

Musts: Passive external plant, single-fiber access, high scalability upgradeability, compatibility with existing PON infrastructure, and excellent network robustness, all at a cost similar to legacy PON technologies.

Sponsored by the European Commission with an investment of 2.6-million Euros, SARDANA (Scaled Advanced Ring-based passive Dense Access Network Architecture) is a three-year research and development project aimed at moving gigabit passive optical networking (GPON) from the ITU-T G.984 standard issued in January 2003 to the new ITU-T G.987 standard, and beyond. G.984 was notable for both its speed (2.5Gbps downstream, 1.25Gbps upstream) and its support of “non-native” transport protocols such as ATM, Ethernet, and TDM, but it has seen limited deployment.4

Its successor, the ITU-G.987 standard issued in June 2010, has become the leading candidate for a gigabit-PON specification for fibre-to-the-home (FTTH) deployment, largely because of ongoing interest from the Full Service Access Networks (FSAN) organization, a group of leading global telecom carriers. FSAN’s own research into 10-gigabit GPON, initiated in 2006, led to a September 2009 white paper which outlines the technical designs and system requirements for two classes of service: XG-PON1, which meets the G.987 standard by providing 10Gbps downstream and 2.5Gbps up, and the symmetric XG-

Participating Organization Country Universitat Politecnica de Catalunya

Spain

France Telecom / Orange France Tellabs USA Intracom S.A. Telecom Solutions

Greece

Instituto de Telecommunicaoes

Portugal

High Institute of Communication and Information Technology

Italy

Research and Education Laboratory in Information Technology

Greece

“SARDANA shakes up PON

technology and brings the potential

for a new suite of high-quality

services to our customers. We’re

very excited to start the field trials

in Lannion, France . . . to

demonstrate both the urban and

rural scenarios of SARDANA.”

-- Dr. Philippe Chanclou,

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PON2, featuring 10Gbps in both directions.5

What makes SARDANA so innovative is its simplicity. By merging the TDM access trees (“last mile”) of today’s networks with the WDM core (“metro”) ring, where multiservice Layer 2 and 3 functionalities now reside, SARDANA will extend these capabilities out to locations which currently rely on a remote central office for them: cellular towers, homes, small businesses, even rural areas. As expected, SARDANA is fully compatible with its predecessor GPON technologies (2.5G-GPON, BPON, and APON), but its true innovations will become clearer as it is implemented in field trials and beyond:

Just one central office with one pump laser will be needed per metro ring, reducing network operating costs. With SARDANA, numerous COs will be replaced by passive nodes requiring no electricity.

100-kilometer (62-mile) signal reach from central offices, far exceeding the 20-to-30 kilometre range of today’s PONs, thanks to erbium-doped fiber amplifiers (EDFAs) passively re-generating the signals and extending them out to more-remote areas of the network. These passive amplifiers are far less expensive and more reliable than electricity-powered pump lasers. SARDANA provides not only scalability, but flexibility as well: carriers can easily add nodes to their networks whenever and wherever they are needed.

32 times more bandwidth on a single-mode fibre than today’s best PONs provide. SARDANA uses wavelength-division multiplexing (WDM) to drive up to 32 different 10-gigabit wavelengths down a fibre where only one now goes. This breakthrough, which delivers 128 times the bandwidth of G.984 GPON, will allow carriers to offer premium-priced, higher-bandwidth service packages to their top commercial customers. And for smaller businesses and residential customers, SARDANA will enable higher split ratios, with up to 1,024 subscribers on a single PON.

Lower-cost, simpler installations at businesses and homes: Many of today optical-network connections rely on a pair of laser transmitters, either tunable or fixed-wavelength, to send and receive one specific frequency of light to and from the end user’s location. SARDANA replaces these transmitters, which can cost as much as $1,000 each, with smaller, “colourless” optical network terminals (ONTs) which might be the single most innovative element of SARDANA. Because they have no laser and need no tuning, these passive ONTs are much less expensive and can manage all 32 incoming wavelengths. The result will be equipment-inventory savings for the carrier and a far simpler array of terminals for installing technicians to keep on their trucks.

Greater network resiliency also results from SARDANA’s dual-ring architecture. For the first time PONs will have a redundancy comparable to Ethernet and legacy SONET platforms, enabling carriers to offer higher-reliability services to businesses—and to keep up with the increasingly stringent demands of today’s Service Level Agreements (SLAs).

Nearly three years in the making, these and other SARDANA capabilities were reviewed at an October 28, 2010 lab-demonstration event at Tellabs’ facility in Espoo, Finland. France Telecom’s senior research expert, Dr. Philippe Chanclou, praised the demonstration (see box) and confirmed his company’s intent to conduct a SARDANA field trial (including high-speed

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Internet, voice, and IP video services) in Lannion, France in January 2011. Both events set the stage for SARDANA to be formally introduced at the Fibre To The Home (FTTH) Council Exhibit in Milan, Italy, February 9 – 11, 2011. As part of their presentation, consortium representatives plan to recommend that the ITU seriously consider incorporating SARDANA into the NG-PON2 standard they are now developing.

Although SARDANA is estimated to be at least 24 months from a possible rollout, Tellabs and other consortium members already are talking about the applications it can enable or dramatically improve, thanks to the major increase in bandwidth it provides with so little added cost. These applications include:

HDTV: 9 megabits per second per channel 3DTV: 9-54 megabits per second per channel UHDTV: 40-144 megabits per second per channel Holographic conference calls Networked video gaming

– Residential – Gaming Industry

High speed B2B traffic Central office consolidation

Besides enabling or improving these and other end-user applications, SARDANA has the potential to help with local loop unbundling (LLU), an issue of particular concern in Europe. The local loop referred to in “LLU” is the physical copper-line circuits in the local access network connecting the customer’s premises to the network operator’s local switch. Because it is neither economical nor feasible for competitive local-exchange carriers (CLECs) to try to duplicate the incumbent local-exchange carrier’s (ILEC’s) local loop, governments and telecom industry groups continue to deal with a long-running debate and negotiations over the terms under which ILECs must make parts of their network available for competitors to lease and use. The issue of LLU is most pronounced in Europe, where numerous developed countries each have their own ILEC and each country sets its own telecom policies.

Once installed, SARDANA technology would offer two possible ways to enable Local Loop Unbundling:

1) The ILEC could lease one or more wavelengths within a SARDANA PON to CLECs who want to serve customers located in the area of that PON, using the “last mile/kilometre” provided by the ILEC. The ability to lease a precise number of wavelengths would be attractive to both ILECs and CLECs.

2) More ambitious CLECs could build their own TDM-tree (“last mile/kilometre”) access networks in selected areas and connect them to the SARDANA ring, operating on only the exact wavelengths they need from the ILEC.

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IV. SARDANA Network Architecture

In search of high scalability and trunk protection, Sardana implements an alternative architecture of the conventional tree WDM/TDM-PON, consisting of the organization of the optical distribution network as a WDM bidirectional ring and TDM access trees, interconnected by means of cascadable optical passive Add&Drop remote nodes (RN), depicted in Fig. 1.

The ring+tree topology can be considered as a natural evolution, from the conventional situation where Metro and Access networks are connected by heterogeneous O/E/O equipment at the interfaces between the FTTH OLTs and the Metro network nodes, towards an integrated Metro-Access network. In this case, covering similar geographical area, users and services, but concentrating electronic equipment at a unique CO, and implementing an all-optical passive alternative, operating as a resilient TDM over WDM overlay. Depending on the scenario, the ring+tree mixed topology optimizes the usage of the fibre infrastructure in the ODN, and also offers enhanced scalability and flexible distribution, as new RNs can be installed.

CO

RN1 RN2

RNi

RNj

RNN RNN-1

1:K

ONONU

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ONONU

ONONU

1:KRSOA

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2N

WDM RING

TDM TREE

D1,…, D

m

Downstream Signals

Upstream Signals

U 1,…, U

2N

U1,…, U

2N

Bidirectional Transmission

PIN/APD

ONONU

ON ONU

ONONU

CO

RN1 RN2

RNi

RNj

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1:K

ONONU

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ONONU

ONONU

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ONU

D m+1,…, D

2N

WDM RING

TDM TREE

D1,…, D

m

Downstream Signals

Upstream Signals

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2N

U1,…, U

2N

Bidirectional Transmission

PIN/APD

ONONU

ON ONU

ONONU

CO

RN1 RN2

RNi

RNj

RNN RNN-1

1:K

ONONU

1:K

ONONU

ONONU

1:KRSOA

ONU

D m+1,…, D

2N

WDM RING

TDM TREE

D1,…, D

m

Downstream Signals

Upstream Signals

U 1,…, U

2N

U1,…, U

2N

Bidirectional Transmission

PIN/APD

ONONU

ON ONU

ONONU

Fig. 1: Architecture model.

The ring topology provides resilience capability and distributed add&drop with a minimal number of links, being the most common topology in metropolitan networks. With the proper design of the Remote Nodes (RN), there are two possible OLT-ONU paths; in case of a fibre failure, the data links are reconfigured and restored, with centralized optical switching at the OLT. This feature becomes more important as the capacity of the access network scales to the high number of served users; in the context of WDM-TDM ODN, it is more efficient as compared to the protection mechanisms defined in ITU G.983. With the hybrid multiplex, the fibre congestion at the CO immediacies is reduced, as 2/4 fibres are required per about 250-2000 users, and it is compatible with scenarios as in urban areas where new fibre deployment can suppose a very high cost, but already a limited number of dark fibres can be available.

The project mainly focuses on the physical layer, specifically on the optical and electro-

8

optical subsystems, trying to be highly transparent to the protocol, coding and bit rate of existing PON standards. With respect to them, the optical parameters are changed (for example the wavelengths band), but the chipset is kept compatible with ngPON, for a smooth migration and interoperability. The ITU-T GPON standard was taken as the reference point, this being also the most stringent in specifications. By means of optical transponders, the adaptation of standard PON systems to Sardana is performed, incorporating the new functionalities. Therefore, Sardana can be regarded as a new transparent optical layer operating at the wavelength domain transparently, that act as traffic collector of existing access systems, and using the existing metro/access optical passive infrastructure. The corresponding multi-operability model in terms of OLT and ONU interfaces is shown in Fig. 2, and a example of physical distribution on the remote nodes and wavelengths per operators is drawn in Fig. 3.

For the full network demonstration, a 10G/2.5G MAC, based on FPGA, in line with xGPON GTC (ITU-T G.987) standard, has been developed in the project, and demonstrated, together with conventional LAN and MAN communications, supporting advanced new broadband multimedia services. Longer term proposals to extend the dynamicity of the traffic control in Sardana have been contributed, as by using Optical Burst Switching for PON in connection to the core network in [2].

SARDANA ONT

SARDANA CO

SARDANA

XGPON

OLT

Sar.OLT

Transponder

SARDANA

PON

xPON

ONU

SERVICE

PLATFORM MUX

&

PUMP

&

ROUT.

&

MONIT.

G/E-PON

OLT

Sar.OLT

Transponder

10G

Ethernet

Sar.OLT

Transponder

Sar. ONU

Transponder

CONTROL (control, monitoring, compensation)

SERVICE

PLATFORM

SERVICE

PLATFORM

SERVICE

PLATFORM

SARDANA Optics Operator

Infrastructure Op.

PON Op. Service Op. PON Op. Service Op.

SARDANA ONT

SARDANA CO

SARDANA

XGPON

OLT

Sar.OLT

Transponder

SARDANA

PON

xPON

ONU

SERVICE

PLATFORM MUX

&

PUMP

&

ROUT.

&

MONIT.

G/E-PON

OLT

Sar.OLT

Transponder

10G

Ethernet

Sar.OLT

Transponder

Sar. ONU

Transponder

CONTROL (control, monitoring, compensation)

SERVICE

PLATFORM

SERVICE

PLATFORM

SERVICE

PLATFORM

SARDANA Optics Operator

Infrastructure Op.

PON Op. Service Op. PON Op. Service Op.

Fig. 2: Sardana interface model.

Fig. 3: PON sharing.

V. Key subsystems.

The implementation of the network subsystems: passive Remote Node (RN), colourless Optical Network Unit (ONU) and the Central Office (CO), encompasses a number of technical challenges. Along the research, although several solutions have been investigated, the decision on the selected one for network demonstration is made on the basis of cost and robustness, leaving more complex advanced solutions for parallel research.

Remote Nodes

The RN is a key element of the Sardana network, and many of the performances and functionalities of the network depend on its design, like protection and routing. They implement cascadable 4-to-1 fibre optical add&drop function, by means of athermal fixed filters, splitters that perform spatial diversity for protection and distribute different wavelengths to each of the access trees, and remote amplification, introduced at the RN by means of Erbium Doped Fibers (EDFs) to compensate add&drop losses; optical pump for the remote amplification is obtained

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by pump lasers located at the Central Office (CO), also providing extra Raman gain along the ring.

This new network element, passive but with dynamic behaviour, incorporated in the new PON, is not present in current standards, but it inherits concepts from the following existing standards:

ITU-T G.984.6 on PON Extender Box, ITU-T G.973 on remotely pumped amplifier (ROPA) for submarine systems, ITU-T G.983 PON protection and ITU-T G.808 Generic protection switching.

The RN encompasses some key challenges, like passiveness in the sense of not using electrical supply, efficient 1480 nm pump use, and burst mode amplification generating gain transients. The inset in Figure 3 shows a RN with 2 drop wavelengths (2 trees) and bidirectional remote amplification in the drop. Wavelength extraction is done by means of two athermal thin-film OADMs at alternated 100 GHz or 50 GHz ITU-T grid channels. The natural gain transients due to the amplification of dynamic burst-modes of the PON upstream are cancelled in this RN thanks to the crossed wavelength direction design and co-amplification of higher power continuous downstream, also avoiding Rayleigh backscattering of the ROPA. The implemented RN presents 1 dB insertion loss in by-pass, 6 dB in drop/add, and >30 dB rejection. The loses are largely compensated by about 14 dB gain of the EDF. In [3] this is compared to other types of Extender Boxes for PONs, in terms of reachable trunk & access power budget. We specify up to 16 RNs, thus 32 wavelength channels, with a splitting ratio between 1 and 32 each.

Lately, a reconfigurable RN has been also assembled, operated with optical power by means of special power converting / harvesting modules, controlling latched optical switches or tunable power splitters, that enter into play at network protection and balancing [4].

Optical Network Unit

A key requirement of the ONU is to be colorless and to reuse the down wavelength, in full-duplex operation compatible with xPON electronics. A reflective-ONU optical transceiver based on RSOA has been taken as preferred option because its simplicity and colourlessness, which solves the provisioning issue of the WDM-PONs. However, it can rise up serious impairments operating in full-duplex with wavelength reuse. To overcome the bandwidth, noise and crosstalk limitations, a complete study of the possible optical modulation formats has been done and several compensating techniques have been developed:

- reduced-ER downstream with feed-forward cancellation at ONU [5] - wavelength dithering to reduce Rayleigh backscattering and reflections [6] - up-stream chirped-managed RSOA with offset-filtering, reaching 10G operation [7] - adaptive electronic equalization, using MLSE and DFE/FFE at 10G [7,8] - integrated colourless optical FSK demodulation with a SOA/REAM [9]. - wavelength shifting at ONU for reduction of Rayleigh scattering [10] - other modulation formats tested like SCM, SSB and homodyne PSK are kept as longer

term research.

Central Office (CO)

The CO centralizes the light generation for the whole network and its control. The new optics

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at the CO includes WDM multiplexers, optical pre/post-amplifiers, equalizers, protection switches and monitors. Protection is centrally actively controlled from the OLT, thanks to the design of the optical plant, that support the protection naturally: the CO decides in what ring direction to send every downstream wavelength channel, depending on the conditions, and the ONU+RN send the remodulated upstream signals via both ring directions diversely for the OLT to choose the best. In this way, interferences are avoided, the PON is kept simple and the CO performs fast ring protection, in less than 50 ms, rerouting the affected channels. A novel WDM-OTDR function integrated, then locates the fault in the PON precisely.

In general, an extended PON access network may suffer from a diversity of physical constrains and problems, especially if low cost components are to be used. The proposed solutions found in Sardana have been demonstrated and presented in the major international forums (more than 70 publications, 5 patent applications and invited papers to OFC, ECOC, OSA-ANIC, ICTON and MIT). They have enabled the achievements of the Sardana goals in different scenarios.

VI. Network tests

As part of SARDANA system integration, the following network functionality has been tested and demonstrated

1) HD-video down-stream

Up to eight HD-video channels delivered simultaneously from SARDANA OLTs to four STBs connected to SARDANA ONUs using a commercial IPTV delivery platform from Intracom.

2) HD-video up-stream

Up to eight HD-video channels delivered simultaneously from CPE through SARDANA ONUs to the CO STB behind the SARDANA OLT using a commercial IPTV delivery platform.

3) p2p Ethernet

Point-to-point Gigabit Ethernet delivery over the SARDANA network wavelength between ONU and OLT sites ePCs showing bidirectional video transmission.

Also showing error free p2p ePC to ePC GE Upstream transmission through the SARDANA network using the ONU RSOA transmitter while simultaneously receiving 10Gbps Downstream SARDANA PON frame and HD video downstream to ONU1.

4) Ring protection switching

Protection switching between the East and West SARDANA ring for p2p GE transmission based on fault detection by monitoring signals built in the protection and monitoring subsystem (P&M) of the SARDANA system.

5) Service control

IPTV service activation/deactivation from the OLT CPC to the ONU CPC via OMCC over the SARDANA XGPON OLT and ONU MAC implementation.

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Different services have run in parallel through the Sardana network over the 4 wavelength channels in operation. Figure 4 shows the network testbed scheme assembled for this demonstrator tests, and Figure 5 a photo of part of the Sardana testbed hardware.

OLT1

10G Switch

Mux

ONU1

split1

VideoServer

W-5km

2km

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Mux

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pamp bamp

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bamp pamp

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split2

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CPC

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5km

split3

2km

ePC

ePC

Fig 4: Network setup for SARDANA demonstrator tests

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Fig. 5: OLT and ONU racks in the SARDANA demonstrator system setup with ePC video screen

VIII. Techno-economical efficiency.

A Quantitative Techno-economic Comparison of the SARDANA network has been performed, and compared to other broadband access architectures [11]. A major infrastructure cost differentiator resides on the organization of the trunk-feeder-drop fibres, linked by means of the respective remote/distribution node.

Four access-metro network architectures were compared in terms of CAPEX/user. Namely metro ring & EP2P, metro ring & GPON and a ring-tree PON with AWG or with add&drop RN, represented by SARDANA (Fig. 6). The outside plant cost as well as the active equipment cost were estimated for all three cases and the overall costs were compared. The results show diversity in costs depending on the HH density and the technology chosen. Cost reduction higher than 20% was found for a wide diversity of scenarios (Fig.7) [10], highlighting that a solution focused on a long reach WDM/TDM PON can be adjusted to the needs of each area and each household. Sardana implements an optimum balance between performances and passive plus active infrastructure utilization.

RN

1 2 NSplitCe

SARDANA

res-WDM/TDM-PON

res-WDM-PON

res-TDM-PON

Fig 6: Detail on the distribution node connections of the different protected PON architectures.

0

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0 1,000 2,000 3,000 4,000 5,00

HH density (HH/Km^2)

Co

st/H

H (

€)

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WDM/PON

GPON

Fig 7: Detail on the distribution node connections of the different protected PON architectures.

VII. Energy efficiency.

Different long-reach optical access networks are studied with respect to their power efficiency. Special focus is dedicated to the hybrid TDM/WDM PON proposed in the SARDANA project, in which remote amplification is utilized for reach extension. The structures of the remote nodes and subsystems for reach extension are shown and discussed in [12]. In principle two SARDANA situations have been considered: SARDANA1 and SARDANA2. First one is SARDANA with “non commercial” devices. Second is SARDANA with market ready

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components.

In Figure 8, the results for unlimited and limited upstream are reported. SARDANA, especially the version 2, expresses the best performances in terms of power efficiency.

The influence of uplink capacity limitation on power efficiency is evaluated, i.e., the access networks’ efficiencies are presented for different CO capacities in terms of Watt per user and per Gbit/s of user’s bandwidth as a function of number of users connected to the CO. The results show remarkable power efficiency degradation for high-speed access technologies in case of strong uplink limitation, while or unlimited uplink case, 10G-EPON and SARDANA networks show the best efficiency.

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Cu = 100 Gbit/s

P-t-P 1G

WDM PON 1G/1G

P-t-P 10G

SARDANA 1

GPON

EPON 1G/1G

Fig 8: Results on the consumption per user and GBit as a function of the number of ONUs per CO, for the uplink

limitation of 100 Gbit/s

VIII. Conclusion

The new all-optically integrated metro-access network proposed in the Sardana consortium has demonstrated practical feasibility, extended performances, functionality and efficiency in terms of cost and energy consumption, aiming towards future FTTH. A number of technical innovative advances, summarized in next table, have been developed to achieve the SARDANA goals.

SARDANA Goals and Accomplishments Summary

Goal How SARDANA Fulfills Goal “One Order of Magnitude” Extension - End Users/PON: Increased from 64 to 1000

- 100-kilometer reach, integrating metro & access - 2.5 Gbps to 10 Gps, for symmetrical 300 Mbps per user

Scalable and Upgradeable - WDM Ring + TDM Trees, flexibly allocated Competitive Cost Structure - End Users/PON: Increased from 64 to 1000

- Complexity centralized at the CO Infrastructure Minimized - WDM Ring + TDM Trees

- Passive External Plant - Bi-directional single fibre access - Identical reflective “colourless” ONUs

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- Down-up wavelength reuse No Maintenance, No Power Needed - Passive External Plant (RN optically powered from CO)Robustness of Network - Dual-ring protection

- Centralized management & light generation - Dynamic EE and resource allocation

Neutral Network - XGPON, GPON, BPON, EPON, 10G Ether. compatible - Multi-operator capable

References

[1] European 7th Framework Programme project SARDANA (www.ict-sardana.eu).

[2] J. Segarra, V. Sales and J. Prat "All-Optical Access-Metro Interface for Hybrid WDM/TDM PON based on OBS," IEEE/OSA Journal of Lightwave Technology, Vol. 25, no. 4, April 2007, pp. 1002 – 1016.

[3] F. Saliou, P. Chanclou, F. Laurent, N. Genay, J.A. Lazaro, F. Bonada and J. Prat. “Reach Extension Strategies for Passive Optical Networks", J. Opt. Com. Networks, vol.1, no.4, Sept. 2009.

[4] A. Baptista et al, “Improved remote node configuration for passive ring-tree architectures”, ECOC 2008, Brussels, Sept. 2008, paper Tu1f6.

[5] B. Schrenk, F. Bonada, M. Omella, J.A. Lazaro, J. Prat, “Enhanced Transmission in Long Reach WDM/TDM Passive Optical Networks by Means of Multiple Downstream Cancellation Techniques”, ECOC 2009, paper We.8.5.4, Vienna.

[6] V. Polo, B. Schrenk, F. Bonada, J. Lazaro and J. Prat, “Reduction of Rayleigh Backscattering and Reflection Effects in WDM-PONs by Optical Frequency Dithering”, ECOC 2008, Brussels, Sept. 2008, paper P421.

[7] M. Omella, I. Papagiannakis, B. Schrenk, D. Klonidis, A. N. Birbas J. Kikidis, J. Prat and I. Tomkos, “Full-Duplex Bidirectional Transmission at 10 Gbps in WDM PONs with RSOA-based ONU using Offset Optical Filtering and Electronic Equalization” OFC 2009, San Diego, Paper OThA7.

[8] D. Torrientes, P. Chanclou, F. Laurent, S. Tsyier, Y. Chang, B. Charbonnier and C. Kazmierski, “10Gbit/s for Next Generation PON with Electronic Equalization using Un-cooled 1.55μm Directly Modulated Laser”, ECOC 2009”, Vienna, PDP Th.3.5.

[9] B. Schrenk, J.A. Lazaro, C. Kazmierski, J. Prat, “Colourless FSK/ASK Optical Network Unit Based on a Fabry Pérot Type SOA/REAM for Symmetrical 10 Gb/s WDM-PONs”, ECOC 2009, Vienna, paper We.7.5.6.

[10] M. Omella, J.A. Lázaro, J. Prat, “Driving Requirements for Wavelength Shifting in Colorless ONU with Dual-Arm Modulator”, IEEE/OSA J. Lightwave Technol., vol. 27, no. 17, Sept. 2009.

[11] S. Chatzi, J.A. Lázaro, J. Prat, I. Tomkos, “A Quantitative Techno-economic Comparison of Current and Next Generation Metro/Access Converged Optical Networks. ECOC 2010, We.8.B.2, Torino, September 2010.

[12] A. Lovrić, S. Aleksić, J.A. Lazaro, G.M. Tosi Beleffi, J. Prat, V. Polo, "Power Efficiency of SARDANA and Other Long-Reach Optical Access Networks", accepted in ONDM’11.

Footnoted Sources

1) “Cable Backhaul: Desperately Seeking Cell Sites” summary http://www.heavyreading.com/cable/details.asp?sku_id=1829&skuitem_itemid=1039&&promo_code=&aff_code=&next_url=/cable/default.asp%3F

2) http://research.rcrwireless.com/index.php?q=node/35

3) http://www.cellular-news.com/story/31118.php

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4) http://www.cn-c114.net/583/a534074.html, page 2 (“Overview”)

5) http://www.pmc-sierra.com/ftth-pon/pon_standards.html