Report of the Technology assessment Group working groups library... · Web viewReport of the Technology assessment Group Presented by Philippe Renaud on behalf of the Contributors

ACP WGC7/WP15 Rev.1

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

Working Group C – 7th meetingMontreal, Canada19 – 23 April 2004

Agenda Item 6: Technology assessment

Report of the Technology assessment Group

Presented by Philippe Renaud on behalf of the Contributors (see section 2)

SUMMARY

As a result of the actions at the ACP WG C6, which established different interest groups to look at new mobile communication systems, this paper summarized the main characteristics of systems which are felt providing significant improvement to the current infrastructure.

Change Record:

Ed Localisation Modifications Reason for change1.0 All Original N/A2.0 New section 3.4 Addition of “Connexion By Boeing”

informationThe information provided by the Author was lost by the document co-ordinator

2.0 New section 3.6 and 3.7

Modification of “Max. number of simultaneously supported users per sector/cell” (UMTS), andRemarks in “Standardisation” (CDMA2000)(identified in red highlighted yellow in Ed 2.0

Editorial

1. Introduction

As resulting from ANC11 7/4 recommendation, ACP WG C has started the investigation of future mobile communication systems which could be integrated in the communication infrastructure circa 2015 to support the aeronautical traffic evolution and the ATM system enhancement.

To progress this work, WG C has formed during its 6th meeting four groups of interest in charge of dedicated items i.e.:

1. Requirements,2. Technology,

Ed 1.01

3. Spectrum, and4. Institutional matters.

This paper is related to the second item, i.e. Technology assessment.It is a co-operative contribution whereby volunteer organisations are describing the main characteristics of potential candidates according to a pre-agreed form.

Section 2 summarises the technologies which have been felt valuable to be evaluated in the view of enhancing the future mobile communication infrastructure.

Section 3 provides a description of each of these proposed technologies.

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2. Potential technologies

Technology organisation contributing to the assessment

B-VHF German Aerospace Center (DLR) (M Schnell)

B-VHF Consortium represented by DLR

ADL (Advanced Airport Data Link), i.e. data link especially designed for the use in the high density airport environment including arrival and take-off

German Aerospace Center (DLR) (M Schnell)

SDLS ESA (C Loisy)Connexion By Boeing Boeing (W Estermann)Aero B-GAN Inmarsat (G Colledge)3GPP UMTS (FDD) Eurocontrol (L Lommaert)CDMA2000 1xRTT Eurocontrol (L Lommaert)

Table 1 – Technologies considered as potential candidate for the future aeronautical mobile communication infrastructure

3. Technology description

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3.1 B-VHF

Development and design of B-VHF has started on January, 1st 2004, within the FP6 European research project B-VHF (“Broadband VHF Aeronautical Communications System Based on MC-CDMA”). Since the system design of B-VHF is not yet finalized, the system description is preliminary and subject to changes.

B-VHFAuthor: B-VHF Consortium

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme FDD or TDD (T.B.D within B-VHF project)Multiple-access scheme CDMA, FDMAModulation types QPSK and QAM, adjustable to channel conditionsFEC Coding Separate FEC schemes for each service type (voice, different data

service classes). Details on FEC schemes T.B.D within the B-VHF project.

Diversity techniques Yes, inherent frequency diversity due to spread-spectrum transmission based on multi-carrier technology.

System bandwidth About 1 MHz (T.B.D within the B-VHF project)Supported data rates per user Up to 128 kbps. In addition, channel aggregation possible.Max. number of simultaneously supported users per sector/cell

Up to 128

Remarks B-VHF is based on the multi-carrier technology and, therefore, highly flexible with respect to exchanging data rate per user and user capacity. Moreover, the multi-carrier technology enables to realize B-VHF as an overlay system in the VHF band, since frequency gaps can be easily utilized.

GENERIC COMMUNICATION SERVICEService 1

Types Voice User throughput 4800bpsUser interface PTT + analogue voice interface to vocoder.Connection topology Air/Ground, Air-airType of QoS Real-time voice operation, 250 ms max. end-to-end delay, FEC as

provided by the 4,8 kbps vocoder.Service 2

Types Addressed data linkUser throughput Up to 128 kbps, dependent on the transition phase.User interface IP, option for integration as an ATN subnetworkConnection topology Point-to-pointType of QoS Time-critical data operation, estimated 10 s typical 95% end-to-end

transmission delay, detailed integrity mechanisms (e.g. FEC) T.B.D within the B-VHF project.

Service 3Types Broadcast (T.B.D. within B-VHF project)

Remarks

TOPOLOGY

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Geographical coverage Cellular terrestrialRange 200 NM from the ground station

Remarks

SPECTRUMCurrent spectrum status Spectrum occupied by the legacy narrowband VHF systems (or a

dedicated sub-band of the VHF spectrum)Propagation Degradation due to broadband channel effectsFrequency Band VHF band, alternatively also MLS bandAvailable spectrum bandwidth Currently, no spectrum is assigned to B-VHF

Remarks VHF spectrum is intended to be used by B-VHF together with legacy VHF systems. Compatibility between B-VHF and legacy VHF systems is guaranteed due to overlay concept.

AIRBORNE INTEGRATIONAvionics Anticipated as a replacement of -/ extension to the VDR 750 radio.

ATN compatibility also requires CMU modifications.Mutual spectrum compatibility Co-location problems with other VHF radios

Remarks

GROUND INTEGRATIONInfrastructure evolution Anticipated as a replacement of ground voice and VDL2 radios, with

external interfaces similar as today.Remarks

SERVICE PROVISIONPossible model Voice part could remain in the ANSP domain, data link part may be

delegated to communications service providers. Remarks

MIGRATION/TRANSITIONIdentified issue Target is an overlay concept, where B-VHF system would locally re-

use – without interference - spectrum ressources that are currently used by the distant narrowband VHF systems. As a fallback, sub-banding may be used.

Allow incremental deployment With an overlay option, incremental per-sector deployment would be possible.

Inband transition Yes, due to overlay concept.Remarks

SECURITYSecurity function supported B-VHF system will be designed to support encryption and other

security applications. Multi-carrier technology combined with CDMA offers a robust physical layer.

Jammer suppression Narrowband jammers are suppressed due to the CDMA transmission (several narrowband multicarriers are used for the transmission of a single bit of information).

Remarks

INDUSTRIAL MATURITYStatus of development of the necessary components by the industry

B-VHF underlying MC-CDMA technology is being developed for the telecommunication industry (4G)

Remarks

STANDARDISATIONStandardisation status No standards available yet.

Remarks

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OTHER IMPORTANTS ASPECT

High level description

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3.2 ADL

The system design for the ADL is not yet finalized, thus, the system description is preliminary and subject to changes.

ADL (Advanced Airport Data Link)Author: DLR

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme FDD / TDDMultiple-access scheme CDMA (Ground/Air) and FDMA (Air/Ground)Modulation types QPSK, QAMFEC Coding Adaptable FEC depending on data or voice service. FEC based on

convolutional coding. Additionally, CRC check for data.Diversity techniques Yes, inherent frequency diversity due to spread-spectrum transmission

based on multi-carrier technology.System bandwidth 8,192 MHzSupported data rates per user From 128 kBit/s to 2 MBit/sMax. number of simultaneously supported users per sector/cell

128

Remarks ADL is based on the multi-carrier technology and, therefore, highly flexible. Data rate per user and user capacity can be exchanged in a simple way allowing to easily adopt transmission to the current requirements.


Types Data (connection-oriented and connection-less)User throughput Up to 2 MBit/sUser interface IP, option for integration as an ATN subnetworkConnection topology Point-to-point, point-to-multipointType of QoS Different priority levels, guaranteed assigned user data rates

Service 2Types VoiceUser throughput Configurable, e.g. 4800 bpsUser interface PTT + analogue voice interface to vocoderConnection topology Air/Ground, Ground/AirType of QoS Real-time voice operation, 250ms max. end-to-end delay

Remarks

TOPOLOGYGeographical coverage Cellular terrestrialRange 30 NM from the ground station

Remarks

SPECTRUMCurrent spectrum status Shared spectrum with microwave landing system (MLS)Propagation Degradation due to multipath propagation mitigated by frequency and

time diversity with propagation channel estimation and equalizationFrequency Band 5 GHz (MLS band)Available spectrum bandwidth 56 MHz

Remarks

AIRBORNE INTEGRATION

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Avionics 5 GHz antenna and new radio equipment necessaryMutual spectrum compatibility Shared with MLS

Remarks

GROUND INTEGRATIONInfrastructure evolution 5 GHz antenna and new radio equipment necessary

Remarks

SERVICE PROVISIONPossible model Future ATC/ATM, A-SMGCS, airport/airline data link services

Remarks

MIGRATION/TRANSITIONIdentified issue Part of the MLS spectrum has to be migrated to ADLAllow incremental deployment Yes, airport-basedInband transition Yes, use unoccupied part of the MLS spectrum

Remarks

SECURITYSecurity function supported EncryptionJammer suppression Narrowband jammers are suppressed due to CDMA transmission

Remarks


Ground/Air link designed, evaluated and implemented in demonstratorAir/Ground link under development

Remarks

STANDARDISATIONStandardisation status Standardisation planned

Remarks



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3.3 SDLS

SDLSAuthor: ESA

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme FDDMultiple-access scheme CDMA (Synchronous and quasi-synchronous)Modulation types QPSK.FEC Coding YesDiversity techniques AES receives from two satellites and transmit through the one it

receives best. Two AESs per aircraft would likely be required.System bandwidth 900 KHzSupported data rates per user From 6.4 Kb/s in global beam to 30 Kb/s in narrower beamsMax. number of simultaneously supported users per sector/cell

Remarks


Types Voice User throughput 4800bps or 2400bps (oceanic)User interfaceConnection topology Air/GroundType of QoS Communication establishment < 5 s

Voice latency < 400msResidual error rate 10-3

Service 2Types ATS and AOC Data services User throughput Up to 20KbpsUser interface Packet serviceConnection topology Point-to-pointType of QoS

QoS 1 Transit delay 5s, RER 10-8 Priority 1 Short Data ServiceQoS 2 Transit delay 5s, RER 10-8 Priority 1 CPDLC high (ACL)QoS 3 Transit delay 10s, RER 10-7 Priority 2 CPDLC medium (ACM.)QoS 4 Transit delay 30s, RER 10-6 Priority 3 CPDLC low (DFIS, AOC…)

Remark Short Data Service is to be used for down-linking of on-board parameters

. . .

Remarks

TOPOLOGYGeographical coverage Geosynchronous satellite: global beam (ocean), regional beams (cont)Range from GES Determined by satellite coverage

Remarks

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SPECTRUMCurrent spectrum status AMS(R)S Allocation (priority access)Propagation Line of sight. Less than 1dB attenuation by rain in service bandFrequency Band L-Band 1.5 and 1.6 GHz.Available spectrum bandwidth Up to 10 MHz ?

Remarks

AIRBORNE INTEGRATIONAvionics Antenna and RF building blocks currently available. Modem to be

developed Mutual spectrum compatibility Compatible with AMSS

Remarks

GROUND INTEGRATIONInfrastructure evolution Existing compatible satellite and GES RF front end infrastructure

Remarks Dedicated infrastructure to be deployed in a longer term on continents as traffic builds up.

SERVICE PROVISIONPossible model Investment in AESs (# 20.000 $ per unit) is the dominating cost item

Remarks Low capacity system dedicated to safety communicationsOnly limited capacity transponders are needed for ATS and AOC data traffic. Voice usage is expected to diminish with time

MIGRATION/TRANSITIONIdentified issue Status of the AMS(R)S L-Band to be improved in the futureAllow incremental deployment Geosynchronous satellites are ideal for incremental deploymentInband transition Only sharing with non priority users in MSS is an issue.

Remarks

SECURITYSecurity function supported Could be addedJammer suppression CDMA techniques are naturally protected from narrow band

interference in particular for non fully loaded systems. Satellite diversity also provides protection

Remarks


Synchronized and quasi synchronized CDMA are commonly used in military tactical communication systems

Remarks

STANDARDISATIONStandardisation status

Remarks


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3.4 Connexion By Boeing

Connexion By BoeingAuthor: Boeing

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme DSSSMultiple-access scheme CDMAModulation typesFEC CodingDiversity techniquesSystem bandwidthSupported data rates per userMax. number of simultaneously supported users per sector/cell

Remarks

GENERIC COMMUNICATION SERVICEService

Types voice and dataUser throughput Forward Link (E-s) up to 1 Mbit/s – Return Link (s-E) up to 5 Mbit/sUser interface IPConnection topology Air/Ground, Point-to-pointType of QoS BER > 10-6

Remark Availability > 99.9%

TOPOLOGYGeographical coverage GSO satellite regional beamsRange from GES

Remarks Up to 75o N & S and oceanic major air routes

SPECTRUMCurrent spectrum status Shared spectrum, currently secondaryPropagation Possible degradation due to rain effects in equatorial regions and below

10,000’Frequency Band Ku – band 14-14.5 GHz (E-s) 11/12 GHz (s-E) Available spectrum bandwidth

Remarks Propagation Delay: > 250 milliseconds for GSO satellites

AIRBORNE INTEGRATIONAvionics No issues envisaged with integrationMutual spectrum compatibility N/A

Remarks

GROUND INTEGRATIONInfrastructure evolution Evolution of ground infrastructure to accommodate IP protocols is

requiredRemarks

SERVICE PROVISIONPossible model

Remarks

MIGRATION/TRANSITION

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Identified issue NoneAllow incremental deployment Considered to be the most practical solutionInband transition

Remarks

SECURITYSecurity function supported EncryptionJammer suppression

Remarks


Technology was initially developed for the telecommunication industry but has been adapted successfully for the AMSS

Remarks

STANDARDISATIONStandardisation status Compliant with ETSI and ARIB

Remarks



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3.5 Aero-BGAN

Aero-BGANAuthor: INMARSAT

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme FDDMultiple-access scheme FDMA/TDMAMultiple-access interference N/AIntersymbol interference Yes (an appropriate allowance is made in the Link Budget design)Modulation types O-QPSK, π/4-QPSK, 16-QAM; FEC Coding Yes – turbo codingDiversity techniques NoSymbol duration 60, 30, 15, 6.7μs (16.8, 33.6, 67.2, 151.2 kbps)Frame duration 5, 10, 20, and 80 msSupported data rates per user Up to 432 kbps (average data throughput) per channelMax. number of simultaneously supported users per sector/cell

Aggregated up to maximum capacity per spot beam. (Approximate maximum of 10% of satellite capacity to a spot beam.)

Remarks


Types Voice User throughput 4800bps AMBE voice codecUser interface 4 wire analogue, and CEPT E1Connection topology Point to point (and Point to Multipoint capability)Type of QoS (target GoS of 4% for APC) Priority and Pre-emption for non-APC

Service 2Types ISDN Connection basedUser throughput 64 kb/sUser interface H.323Connection topology Point-to-pointType of QoS (target GoS of 4% for APC)

Service 3Types IP based Connectionless dataUser throughput User defined up to 432 kb/sUser interface IETF standard (Ethernet based)Connection topology Point-to-point, Unicast, MulticastType of QoS User request

TOPOLOGYGeographical coverage GEO Satellite global, regional and spot beamsRange N/A

Remarks

SPECTRUMCurrent spectrum status Shared L band MS(R)S spectrumPropagation Line of sight down to 5 degrees elevation to satelliteFrequency Band L band (1525MHz-1559MHz RX and 1626.5MHz – 1660.5MHz TX)Bandwidth Shared co-ordinated Inmarsat Spectrum

Remarks For BGAN the spectrum is subdivided in 200kHz channels

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AIRBORNE INTEGRATIONAvionics Integration with Aero-H/H+ using common RF infrastructure (HPA

and antenna)Mutual spectrum compatibility As per ICAO AMSS SARPs and RTCA DO-210D

Remarks

GROUND INTEGRATIONInfrastructure evolution Ground infrastructure for Aero-H/H+ is independent from Aero-

BGAN. Inmarsat is procuring and deploying BGAN ground infrastructure. (Infrastructure operational mid-2005)

Remarks

SERVICE PROVISIONPossible model TBD

Remarks

MIGRATION/TRANSITIONIdentified issue Parallel integrated operation of Aero-H/H+ services and Aero-BGAN

services.Allow incremental deployment YesInband transition Yes

Remarks The integrated nature of the equipment will allow transition from Aero-H/H+ to Aero-BGAN based services as the user base requires.

SECURITYSecurity function supported User defined encryptionJammer suppression No

Remarks


Technology has been developed for the telecommunication industry (3rd Generation UMTS with defined satellite interface)

Remarks

STANDARDISATIONStandardisation status (Land mobile service development leads)

Remarks Co-ordinating with AEEC to incorporate Aero-BGAN into existing characteristics

OTHER IMPORTANTS ASPECTTBD

High level descriptionTo be completed

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3.6 3GPP UMTS (FDD)

3GPP UMTS (FDD)Author: EUROCONTROL

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme FDDMultiple-access scheme CDMAModulation types Data : BPSK uplink , QPSK downlink.

Spreading : QPSK up and downlinkFEC Coding Low data rate (<32kbps) : 1/3 or ½ Convolution coding K=9

High data rate : 1/3 Turbo coding (PCCC) Diversity techniques Space : Base station antenna diversity standardisedSystem bandwidth 2 x 5MHz Occupied Bandwidth / 3,84 Mcps (FDD/Down and Uplink)Supported data rates per user 12,2 - 64 - 144 - 384 kbps typical with test scenario for BER in

standard. Any data rate can be used as long as the rate is pre-defined (multi rate puncturing-repetition).

Max. number of simultaneously supported users per sector/cell

Pole capacity = 98 users/cell (voice channels) within an omni directional cell.

Remarks CDMA/FDD uses down/uplink isolation in the frequency domain. Relative FDD frequency separation should be at least 10% preferable 15%.

CDMA is an interference limited system. Its cell capacity limit is sooner reached by its interference level limit rather than by its code availability.limit. Hence CDMA is said to have a SOFT capacity.

All commercial telecom service providers base their next generation cellular coms on CDMA as this technology provides the largest user capacity and greatest flexibility vis-à-vis data rates and QoS.

CDMA radios normally transmit at much lower power levels compared to narrow band and/or TDD radios. While analogue (digital) narrow band radios need a SINAD of +12 dB (C/I of +9 up to +11 dB ) a wideband radio operates on negative SIR levels of around -15 dB! The actual SIR value being determined by CDMA processing gain which is function of spreading factor.

UMTS FEC is best on the market today. Turbo coding gets very close to theoretical SHANNON limit.


Types voiceUser throughput 12,2 kbps max when using variable rate vocoder ( rate is variable and

decreases in function of speech activity). User interface Microphone – Earpiece Connection topology Air/Ground. Point-to-point. Connection oriented – often circuit

switched. VOIP also available.Type of QoS Real Time Conversational class (stringent & low delay).

A BER of 1.10-3 is sufficient to provide normal speech qualityService 2

Types Data on dedicated channel (connection oriented at air interface)

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User throughput 12,2 - 64 - 144 - 384 kb/s or any other pre-defined data rateUser interface TBDConnection topology Point-to-point. Circuit switched standardised - ATM standardised - IP

standardised. Type of QoS Real Time Conversational – Real Time Streaming Class

Service 3 Types Packet data (connectionless at air interface)

User throughput 12,2 - 64 - 144 - 384 kb/s or any other pre-defined data rateUser interface TBDConnection topology Point-to-point – Point to Multipoint – Limited Broadcast

Packet switched standardised - ATM standardised - IP in standardisation process

Type of QoS Interactive and background class / best effortRemarks Throughout this whole document ATM stands for Asynchronous

Transfer Mode.

As UMTS incorporates a multi-rate adapter any data rate can be transmitted as long as the rate is predefined for puncturing/repetition.

UMTS FDD allows a change in data rate every 10 ms as each frame carries a transport format combination indicator (TFCI). UMTS also allows asymmetric data transfer (downlink data rate being different from uplink one). However the amount of asymmetry is having an impact on the user capacity of both down/uplink (interference limit and/or code usage). Therefore amount of asymmetry will be limited.

TOPOLOGYGeographical coverage Cellular terrestrial Range Function of frequency band to be allocated. VHF band 160-200 NM

expected with omni and TX of 3W only. MLS C band 25 NM with omni and TX of 2W – 50 to 70 NM with High gain (10dB).

Remarks Besides transmit power and frequency band allocation the cell range is also function of cell loading and spreading factor employed.

SPECTRUMCurrent spectrum status Request for new spectrum assignment to be forwarded at WRC07Propagation C band : 0,133 dB / Vert Pol (D3 Crane Model) : degradation due to

rain effectsFrequency Band Optimal spectrum allocation would be VHF-UHF bandAvailable spectrum bandwidth 5MHz needed for Downlink – another 5 MHz needed for Uplink(FDD)

Remarks As CDMA has a frequency reuse factor = 1 (all cells operate on the same frequency) a second frequency pair will be needed for aviation due to the existence of the radio horizon. The radio horizon induces between large adjacent cells a silence area. In case a TMA / airport would be located within such a silence area a second set of frequency pairs is needed to serve this unit.

AIRBORNE INTEGRATIONAvionics A guard band is to be foreseen between any analogue narrow band and

a digital wideband radio. Mutual spectrum compatibility CDMA signals behave as additional white Gaussian Noise ( AWGN )

and has as effect to decrease the sensitivity of other receivers in case they would be located in the guard bands

Remarks CDMA in general emits with low power and does in general not create energy bursts (except during compressed, DTX and packet data mode).

Note: the 5 MHz channels spacing foreseen in UMTS is not the 3 dB

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bandwidth!

GROUND INTEGRATIONInfrastructure evolution Ground infrastructure exists but is mostly ATM based. Full IP

infrastructure has been standardised end 2002 (Release 5).

Ground infrastructure consists of BTS/RNC and CN. CN might be circuit switched/ packet switched or both.

The RF Front end of a BTS needs to be converted from auctioned RF spectrum towards ICAO COM spectrum.

UMTS does not need GPS synchronised BTS but can use it. Remarks UMTS RAN deployment and implementation should be part of other

ground infrastructure projects such as iPAX (IPV6 based).

RAN infrastructure as standardized contains lots of functions which are inherited from previous 2G systems such as GSM. It is obvious that UMTS RAN for ATC should not carry the burden of this backward compatibility. Therefore some effort is needed for optimizing the ground infrastructure for ATC operation. Also the UMTS RAN standardized security functions are to heavy for ATC use. Parts such as SIM, HLR, VLR should be carefully investigated and probably deleted from the reference network.

SERVICE PROVISIONPossible model UMTS could not only supply safety-of-life services but AOC and APC

as well. APC service will however consume scarce spectrum resources. In addition a connection to a public network and the installation of an expensive billing system is needed.

Remarks Prime service should be ATC. AOC could be supported but with low priority.

MIGRATION/TRANSITIONIdentified issue Implementation phase can only take place when additional spectrum is

granted. Seen the large UMTS bandwidth and the heavily used VHF band no big bang operation can ever work out.

Allow incremental deployment Only possible with green field spectrum.Inband transition Not possible

Remarks WRC07 spectrum allocation process is determining all future com systems for ATC. States are requested their full support in order to obtain enough spectrum at WRC03.

SECURITYSecurity function supported UMTS includes many security functions. Part of it is inherent

embedded in the CDMA technology through the assignment of codes. Additional security functions are provided at network access, network domain, user domain and application domain levels such as : User authentication through SIM/HLR/VLR.Data Encryption is standardized not only over the air interface but includes also Node B – RNC interface.End to end node data encryption using IPSec

Jammer suppression Yes, narrowband signals are spontaneous suppressed by the CDMA despreading.

Remarks Any Jammer signal is seen as interference and hence has an impact on cell capacity. CDMA copes extremely well with self interference.

An overlay on spectrum occupied by high power narrow band users should be excluded in order to preserve CDMA high user capacity.

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Many UMTS components are available on the market ( e.g. MSM 5000-6000 series from Qualcomm). The RF components cannot be used for ATC as the frequency band will different. Depending the new spectrum allocation for a future Terrestrial Com System some components may be used ( function of Doppler compensation ).

Remarks During ANC-11 the request was made that any new radio system must be backward compatible with existing radio com format. Therefore the future terrestrial com radio will be software defined (SDR).

STANDARDISATIONStandardisation status Standardisation process is done through the 3GPP forum.

The Air interface standard is known as R99. Release 5 contains new air interface for HS-DSCH which is not relevant for ATC as it provides a very high data rate in downlink only.

However Release 5 is very important for the All IP based ground infrastructure definition know as Internet Multimedia Subsystem (IMS)

Remarks Though work on standardisation is still evolving to include higher data rates these new releases have no useful impact on the air interface as specified in R99 when ATC functionality is considered only. A larger downlink data rate can only be useful for APC which is not Eurocontrol’s priority.

OTHER IMPORTANTS ASPECTUsing existing standards has large benefits :

ICAO standardisation procedure can rely on existing standards. UMTS standard modification for ATC operation is believed to remain limited to adaptation of frequency bands, power classes, X-tal accuracy at air interface level.

Telecom equipment manufacturers such as Qualcomm, Alcatel, Siemens, Motorola, Ericsson have spent an estimated 50.000 man years on developing 3GPP(2) standard compliant equipment. Therefore it may be assumed that UMTS technology is technology wise the most advanced at this moment. As newer standards such as 4G, UWB all concentrate on higher data rates this has as consequence that modulation schemes (64 -256 QAM) are more efficient but can only serve users in smaller cell areas.

In Europe the EC has spent more than 6 billion euro in R&D funding on 3GPP over the last 15 years ( on programmes such as RACE I, ACTS( FRAMES), CODIT, ATDMA, SIG5).


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CDMA MAIN ADVANTAGE IS ITS HIGH USERS CAPACITY. This high capacity is obtained through two main factors :

1. CDMA is a cellular based communication system2. CDMA is the only cellular system that operates with a frequency re-use factor of 1 (or cluster size = 1)

MOBILE CELLULAR COMMUNICATION SYSTEM: A mobile cellular communications system strength lies in its radio interference behaviour. Many analogue radios transmit continuously at full power often resulting in signal quality levels which are not needed but at the same time creating large RF interference levels. A cellular mobile system handles a large number of low-power wireless transmitters. By controlling the transmit power, cells can be sized according to the user density and demand within a certain geographical area. Each user’s transmit power is controlled in such a way that signal integrity at the receive side is sufficient for the service to be provided to that particular user. Hence RF interference levels are optimised leading spontaneously to an optimised cellular user capacity. CELLULAR SYSTEM CELL SIZE: Reduction of cell size increases the spectral efficiency within a geographical area. When the traffic demand in a cell increases and reaches a point so that the existing spectral allocation in that cell could not support any longer a good grade of service, the cell could be subdivided in a number of smaller cells (cell splitting). Or cells could be split up into sectors. Smaller and/or sectorized cells will dictate users to transmit with lower transmitter power levels compared to the full-sized cell while at the same time increasing cell capacity by a multiple of the original cell capacity. For example the CDMA cell capacity is increased by a factor of 2,5 for a 3 sector cell and a factor 5 for a 6 sector cell. CDMA/FDD FREQUENCY RE-USE: The most important feature of CDMA/FDD is that its cell frequency reuse factor is equal to one, meaning that all adjacent cells use the same frequencies. Hence the large user capacity a CDMA cell can cater for. All other cellular FDD systems (non-CDMA such as GSM) have a lower capacity because the frequency reuse factor is at least 3 (most technologies have an N= between 3 and 7). CDMA BASICS: CDMA stands for Code Division Multiple Access. CDMA makes use of a spread spectrum technology. The information signal bandwidth is expanded (spread) by a hundred fold or more by multiplying the data with a code. This large increase of bandwidth (also called spreading gain) provides a corresponding increase in interference rejection. A large number of CDMA signals share the same frequency channel, and if viewed either in the time or frequency domain, CDMA signals appear to be on top of each other. CDMA users are uniquely identified by a code sequence, embedded as an address, within the carrier waveform.SPREADING-DESPREADING-JAMMER REJECTION: Applying a pseudo random noise source (PN code sequence) to a data signal spreads the energy of the original data signal over a much wider bandwidth. This combination of data and code sequence is put onto the air. Besides the transmitted signal, the receive antenna also picks up background noise, external interference, interference from other cell sites, and interference from other users within the same cell. By applying at the receive side to the overall received signal an identical PNnoise source (=code) the data can be recovered (despreading or code correlation) leading again to the original narrowband signal. During the same process background noise and other sources of interference will be spread out. The interference, now being wide band while the information being narrow band, can be greatly reduced by low pass filtering.CDMA’s PROCESSING GAIN: CDMA’s processing gain is a function of the bandwidth of the data signal versus the bandwidth of the spread signal. The wider the spreading, the higher the gain. In UMTS a 12,2 kbps data rate has a spreading factor of SF=128 resulting in a processing gain of 24,9 dB ( 10xlog(3,84M/12,2K). CDMA is the only technology where such processing gain exists. This processing gain is added in the link budget calculation. (While link budget is improved with 24,9 dB it is deteriorated by 3 (6) dB due to cell loading of 50% (75%). CDMA POWER CONTOL: Adaptive control of power level settings is one of the cornerstones of cellular communications, in particular CDMA. CDMA’s working concept is based on the principle that the power of all mobile units is controlled so as to arrive at the base station at an equal level, regardless if a user would be very close or very far from the BTS (near far effect). This implicitly requires the simultaneous existence of both a down and uplink channel and operate always in duplex. UMTS power control takes place 1500 times per second. CDMA SECURITY FEATURES: for ATC purposes the standardised UMTS security features are too far fetched. CDMA has already inherently some basic security features integrated in its concepts. For the user part (A/C) several million codes are available for assignment together with up to 256 OVSF codes. For the BTS 512 scrambling codes combined with up to 512 OVSF codes are available. Many other security features are part of the standard – from authentication up to data encryption in various stages. Security features have been set up in such a way that real time eavesdropping is impossible and deciphering is only possible in delayed time (depending computing performance). Security can also be implemented at end nodes at application level through e.g IPSec.

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3.7 CDMA2000 1xRTT

CDMA2000 1xRTTAuthor: EUROCONTROL

ITEMS DESCRIPTIONAIR INTERFACE TECHNOLOGY Duplexing scheme FDDMultiple-access scheme CDMA : CODE DIVISION MULTIPLE ACCESSModulation types Forward Link data QPSK | Reverse Link data BPSK

Forward Link spreading QPSK | Reverse Link spreading HPSK FEC Coding Forward link : Convolutional code ¼ (RS1-RC3) or ¼ (RS2-RC5)

Reverse Link : Convolutional code ½ ( RS1-RC3) or ¼ (RS2-RC4)Both convolutional coders operate with constraint length K=9.

Note1: for data rates > 14,4 kbps a turbo coder ( ½ -1/3 – ¼ ) has been specified for the supplemental channel SCH.

Note2: A forward link RS1/RC4 exists also with other data rates and for convolutional encoder R=1/2 and K=9

Diversity techniques Yes : BTS transmit diversity on 2 antennas(TD). Space diversity. System bandwidth 1,25 MHz (3dB) 1,2288Mcps ( Associated spreading Rate 1)Supported data rates per user RS1/RC3 : 1,2-2,4-4,8-9,6kbps (EVRC-QCELP) for voice

Data : as per voice + 19,2-38,4-76,8-153,6kbps with R=1/4

RS2/RC5(F)4(R) : 1,8-3,6-7,2-14,4kbps(ACELP) for voiceData : as per voice + 28,8-57,6-115,2-230,4kbps with R=1/4

Max. number of simultaneously supported users per sector/cell

Pole capacity = 27 users/cell (voice channels) within an omni directional cell.

Remarks Within this doc only CDMA20001xRTT has been considered as it is the only FDD narrow band CDMA version available. This is important as during WRC07 not enough spectrum may be allocated for a future terrestrial ATC com system based on UMTS.

RC = radio configuration as specified in 3GPP2 (C.S0002-C) and is f (data rate, channel encoding & modulation parameters supported on traffic channel).

RS = Rate Set and determines voice vocoder basic data rate.

SR = Spreading Rate : 1 means 1,228 Mcps / 3 means 3,6864 Mcps

CDMA2000 has in some Forward RC as option CCSH (Code Combining Soft Handover) together with TD.

The traffic channel can have any data rate from 750 bps up to 14,4 kbps.

In case higher data rates are needed 1 or 2 supplemental channels can be added with data rates as defined above and in function of RC.

CDMA2000 1xRTT standard uses the same word “MULTIRATE” for indicating the use of variable data rates. However CDMA2000 does not allow the transmission of ANY data rate as in UMTS but only allows

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the insertion of 1-2 supplementary channels in addition to the fundamental one.

All CDMA2000 BTS need to be synchronised by GPS in order to be able to make a soft handover.

CDMA is an interference limited system. Its cell capacity limit is sooner reached by its interference level limit rather than by its code availability limit. Hence CDMA is said to have a SOFT capacity.CDMA radios normally transmit at much lower power levels compared to narrow band and/or TDD radios. While analogue (digital) narrow band radios need a SINAD of +12 dB (C/I of +9 up to +11 dB ) a wideband radio operates on negative SIR levels of around -15 dB! The actual SIR value being determined by CDMA processing gain which is function of spreading factor.


Types voice on traffic channelUser throughput Vocoder either based on 9,6 or 14,4 kbps depending Rate Set

1( EVRC-QCELP) or 2 (ACELP)User interface Microphone – EarpieceConnection topology Air/Ground - Normally Circuit switched - Packet switched ( VOIP)

possibleType of QoS Real Time conversation class ( low delay-low latency)

Service 2Types Connection oriented data (fixed) on traffic {and supplemental

channel}User throughput RS1/RC3 : 1,2-2,4-4,8-9,6-{ 19,2-38,4-76,8-153,6}kbps

RS2/RC5(F)4(R) : 1,8-3,6-7,2-14,4-{ 28,8-57,6-115,2-230,4}kbpsUser interface TBDConnection topology Point-to-point : Circuit or Packet switched (PDSN)Type of QoS Real Time Conversational class , Real Time streaming class

Service 3Types Packet Data - Connectionless on traffic {and supplemental channel}User throughput RS1/RC3 : 1,2-2,4-4,8-9,6-{ 19,2-38,4-76,8-153,6}kbps

RS2/RC5(F)4(R) : 1,8-3,6-7,2-14,4-{ 28,8-57,6-115,2-230,4}kbpsUser interface TBDConnection topology Point to Point – Point to multipoint – Broadcast / Packet switched

(PDSN) / IP ( simple IP or mobile IP )Type of QoS Interactive and background class / best effort

TOPOLOGYGeographical coverage Cellular terrestrialRange 150-200 NM from the ground station but pilot modification needed.

Remarks CDMA2000 uses a single unique PN code as PILOT which is always broadcast by each BTS. BTS differentiation (needed for soft handover) is enabled by providing a different time offsets (PILOT_INC) to the PILOT of each individual BTS. This concept leads to serious cell range limitations. E.g. Cell ranges of 100 km result in the deployment of maximum 8 cells/sectors only. To avoid this problem and be able to deploy a large amount of large CDMA2000 cells L1 has to be modified.

Eurocontrol has studied this issue already and can propose a simple way with minimum modifications to the standard.

SPECTRUM

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Current spectrum status Spectrum allocation to be requested at WRC07. Preference given to VHF/UHF band

Propagation VHF/UHF is not degraded due to rain effectsFrequency Band TBDAvailable spectrum bandwidth At least 2x (1,25 MHz + guard band) should be allocated for a single

forward/backward link. Note : No guard band is needed in between 2 or more forward / backward links.

Remarks CDMA2000 is an FDD system so forward/backward links need to be isolated in the frequency domain. Relative FDD frequency separation should be at least 10% preferable 15%.

In order to avoid silence areas in between large cells a second forward/backward frequency pair is needed (see UMTS).

Eurocontrol proved in 2001 that 18 simultaneous channels could be set up with a prototype. This should allow the simultaneous connection of at least 12 voice channels within a cell dealing with approach, tower, ground, upper airspace, vhf2,….etc within that cell.

AIRBORNE INTEGRATIONAvionics As CDMA always operates in FDD mode the TX is always on.

Fortunately CDMA emits far less power (< 3W) than any existing airborne radio. Existing radios emit > 15 W but all have a small duty cycle. CDMA TX and RX simultaneously on the same antenna. Hence the need of a duplexer behind the antenna.

Mutual spectrum compatibility Because CDMA behaves as AWGN any interference on narrow band systems would lead to a RX sensitivity increase. A guard band must be foreseen between any narrowband analogue and digital radio.

Remarks CDMA needs an ultra linear amplifier. The concept of e.g pre-distortion amplifiers is that linearity increases dramatically while at the same time the amplifier size decreases dramatically as well ( less cooling needed and PA operation in class AB). However within a 3MCU unit the duplexer should be integrated as well.

GROUND INTEGRATIONInfrastructure evolution CDMA 1xRTT ground infrastructure evolves to an all-IP network.

Remarks Mainly ANSI-IS-41 or GSM-MAP or all-IP connectivity

Ground infrastructure consists of BTS/BSC and MTSO. MTSO might be circuit switched/ packet switched based or a combination of both.

The RF Front end of a BTS needs to be converted from auctioned RF spectrum towards ICAO COM spectrum.

CDMA2000 1xRTT needs GPS synchronised BTS.

SERVICE PROVISIONPossible model CDMA2000 could not only supply safety-of-life services but AOC and

APC as well. APC service will however consume scarce spectrum resources. In addition a connection to a public network and the installation of an expensive billing system is needed.Pls note that the CDMA capacity is only 1/3 of UMTS

Remarks Prime service should be ATC. AOC could be supported but with low priority.

MIGRATION/TRANSITIONIdentified issue Implementation phase can only take place when additional spectrum is

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granted. Seen the CDMA20001xRTT bandwidth and the heavily used VHF band no big bang operation can ever work out.

Allow incremental deploymentInband transition Only possible with green field spectrum.

Remarks WRC07 spectrum allocation process is determining all future com systems for ATC. States are requested their full support in order to obtain enough spectrum at WRC07.

SECURITYSecurity function supported CDMA is already secured natively by its 2^42 PN Long code

(Backward link) and Walsh code + 2^15scrambling code( forward link) for data and voice.

CDMA uses standardized CAVE to generate 128 bit SSD. The 64 bit A-Key, ESN and network supplied RANDSSD are input to CAVE generating the SSD.

Jammer suppression Yes inherently linked to CDMA systems. Narrow band jammers are suppressed at the RX side after dispreading.

Remarks See UMTS : Security functions are overdone and should be simplified for ATC.


Standard is evolving continuously due to pressure from service providers having deployed IS95A/B.

Remarks CDMA2000 standards are not obvious to read due to the many radio configurations and 2 different vocoders. Its origin is linked with the use of CDMA at 2G (IS95A&B) level in the USA. The backward compatibility needed is leading to a lot of overhead in the standards.

STANDARDISATIONStandardisation status Standard approved by 3GPP2 committee & ANSI/TIA/EIA

Remarks Standards as EV-DO and EV-VD are recently developed but are not to be considered for ATC as in our case high data rate forward ( BTS-A/C) are not needed. Within ATC the backward link (A/C-BTS) is expected to carry most of the data volume.

Last in the row of standards is CDMA2000 1xRTT. The 3xRTT has not been finalised yet.

OTHER IMPORTANTS ASPECTUsing existing standards has large benefits :

ICAO standardisation procedure can rely on existing standards. CDMA2000 standard modification for ATC operation needs adaptation of frequency bands, power classes, X-tal accuracy and MODIFICATION OF LAYER ONE FOR PILOT AND PILOT ACQUISTION ISSUES

CDMA 2000 is mainly driven by Qualcomm who owns most of the patents (even on wave shape). As it is based on 2G communications IS95 A and B many intermediate standards exist.

As newer standards such as 4G, UWB all concentrate on higher data rates this has as consequence that modulation schemes (64 -256 QAM) become more complex. Because these complex modulation schemes have smaller Eucledian distances between symbol constellation points - leading to a very efficient spectrum use- this has as a consequence that only small cell areas ( 0,5-2 km) can be covered..

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High level descriptionThe reader is requested to read all info provided in the UMTS proposal because it is also applicable to this “narrowband” CDMA version.

In case WRC07 assigns enough spectrum to ATC, UMTS CDMA should be preferred. The wider a signal can be spread the better it is protected against jamming , the higher the processing gain and the larger the eventual user capacity will be.

In case ACP would opt for CDMA2000 1xRTT than the audience should be aware that some additional standardisation is needed at layer 1 level in order to be able to support large cell ranges. In addition to the outcome of a study let by Eurocontrol some more simulation work is needed. After a positive outcome a more detailed acquisition procedure should be investigated and standardised.

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