EUROCONTROL EXPERIMENTAL CENTRE · EUROCONTROL Experimental Centre B.P.15 F ... AIRCOM Airborne Communications. Ipv6 ... GSM Global System for Mobile communications

EUROPEAN ORGANISATIONFOR THE SAFETY OF AIR NAVIGATION

EUROCONTROL EXPERIMENTAL CENTRE

ISA PROJECT(Ipv6 - Satellite - Atm for ATN)

SATELLITE PERSPECTIVES FOR CNS/ATM

EEC Note No. 29/97

EEC Task D14

Issued: December 1997

The information contained in this document is the property of the EUROCONTROL Agency and no part should be reproduced in any formwithout the Agency’s permission.

The views expressed herein do not necessarily reflect the official views or policy of the Agency.

EUROCONTROL

REPORT DOCUMENTATION PAGE

Reference:EEC Note No. 29/97

Security Classificat ion:Unclassified

Originator:EEC - TEL(TELecom Centre of Expertise)

Originator (Corporate Author) Name/Location:EUROCONTROL Experimental CentreB.P.15F - 91222 Brétigny-sur-Orge CEDEXFRANCETelephone : +33 01 69 88 75 00

Sponsor: Sponsor (Cont ract Authority) Name /Location:

TITLE:

ISA PROJECT(Ipv6 - Satellite - Atm for ATN)

SATELLITE PERSPECTIVES FOR CNS/ATM

Authors L. Crouzard

G. Gawinowski C. Musson

Date

12/97Pages

iii + 26Figures

-Tables

1Appendix

2References

4

EATCHIP TaskSpecification

EEC Task No.

D14

Task No. S ponsor Period

10/1997 to 12/1997

Distribution Stat ement:(a) Controlled by: Head of AMS(b) Special Limitations: None(c) Copy to NTIS: YES / NO

Descriptors (keywords):

GEO/MEO/LEO satellite systems for Communication, Navigation and Surveillance / Air TrafficManagement, COTS technologies, Asynchronous transfer mode, Internet Protocol next generation,Aeronautical Telecommunication Network

Abstract:

This report analyses the particular situation of CNS/ATM applications based at the present time on specificproducts, in order to determine the possibility to get benefits of COTS technologies associated with satellites. Italso includes a full description and comparison of the GEO/MEO/LEO satellite systems.

This document has been collated by mechanical means. Should there be missing pages, please report to:

EUROCONTROL Experimental CentrePublications Office

B.P. 1591222 - BRETIGNY-SUR-ORGE CEDEX

France

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Table of Contents

1. INTRODUCTION 1

1.1. Present situat ion for Satcom CNS/ATM 1

1.2. References 2

1.3. Web sites 2

1.4. Definitions and Acronyms 2

2. THE PRESENT SATELLITE SYSTEM 4

2.1. INMARSAT 4

3. SATELLITE PROJECTS COMPLIANT ICAO 7

3.1. The Satellite Data Link System (SDLS) 7

3.2. IRIDIUM’s LEO-satellite system 9

3.3. GLOBALSTAR’s LEO-satellite system 11

3.4. ICO’s MEO-satellite system 11

3.5. MTSAT’s GEO-satellite system 13

4. BROADBAND SATELLITE SYSTEMS PROPOSALS 15

4.1. TELEDESIC 15

4.2. CELESTRI 17

4.3. SKYBRIDGE 18

5. SUMMARY 20

6. CONCLUSION 21

APPENDIX 1: DEFINITIONS 23

APPENDIX 2: CONTACTS 26

Ipv6 - Satellite - Atm for ATNSatellite Perspectives for CNS/ATM

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1. Introduction

Today, large public markets represent a strong booster for emergent telecom and networktechnologies. Internet and UMTS (Universal Mobile Telecommunication System) are themain actors which will permit COTS technologies and cost-effectiveness. The satellite mediaappears to play an important role in the deployment of the required infrastructure.Consequently, present satellite evolution is focused on providing COTS services for Internetand UMTS, hence new LEO (Low Earth Orbit) satellite generation is emerging.

As satellite should be considered as one of the media support solutions for Air-Ground andAir-Air CNS/ATM (Communication-Navigation-Surveillance, Air Traffic Management)applications, it is interesting to analyse this potential and this opportunity window to getbenefits of new satellite technology generation.

This report analyses the particular situation of CNS/ATM applications based at the presenttime on specific products, in order to determine the possibility to get benefits of COTStechnologies associated with satellites. It also includes a full description and comparison ofthe GEO/MEO/LEO satellite systems.

1.1. Present situation for Satcom CNS/ATM

ICAO (International Civil Aviation Organisation) is responsible for all the standardizationprocess of the aeronautical domain. For this reason, the international aviation community hasstandardized the telecommunication part relative to satellite links (ICAO standards for AMSSand ATN). The implementation took place only after, with experimentations of Air-Grounddata transmission over satellite (Inmarsat GEO satellite). The analysis of the systembehaviour in ADS-Europe trials casts some doubt on the overall feasibility to operateefficiently the present system in high density areas [Ref. 1]. The result is that for a low-bandwidth Inmarsat Satcom provides low reliability, poor performance (important protocoloverhead which provides 10-15 seconds of latency time) and very high cost. This is aproblem of methodology.

• Standardization occurred before the implementation and experimentations. As thestandardization is a heavy and expensive process, it is now very difficult to modify thestandards. However, it is admitted [Ref. 2] that ICAO standards appear very unlikely tooffer reasonable performances and affordable costs...

• The critical problem is that the current standards of the telecom-network world-wideevolution are imposed de facto by the industry and ICAO standards cannot follow them.CNS/ATM shall support the extra-cost of specific products and it represents an ante-COTS situation.

• The aeronautical philosophy is to have long-term and stable technologies and standardsdue to safety and certification constraints, but it has never been tried to adapt the processto permit implementation with evolutive technology.

It is important to keep in mind that no other satellite provider (GEO, MEO or LEO) couldpropose a better solution/system (quality of service, performance, low-cost) than the presentGEO-Inmarsat with the constraint to be ICAO compliant.

• A one-way delay is about 250 ms for a GEO satellite, and 10 ms for a LEO satellite.Compared with the 15 s of the overhead protocol, there is little difference between 250 msand 10 ms : no improvement of the performance.

• The cost will be not very different between GEO, MEO and LEO satellites. Firstly :

satellite providers have an extra-cost to be ICAO compliant (specific products); secondly :specific ICAO protocols have poor performance in terms of optimized bandwidth whilesatellite communication cost is depending on the bandwidth required.


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Why would a satellite provider offer ATS services with the constraint to be ICAO compliant(to have specific services due to specific products) on a very limited market in terms ofbusiness-case ?

In the aircraft, the bandwidth-services and in consequence the business-case is not for ATSbut for APC (Aeronautical Passenger Communications) applications with the particularity thatAPC applications do not require to have the ICAO compliant protocols.

• New LEO satellite providers are mainly (only) interested to provide APC multi-media high-bandwidth applications.

• ATS (ICAO compliant) and APC (no ICAO compliant) applications would have differenttechnologies of communication. Return on investments of ATS equipment retrofit wouldnot be shared by APC due to difference of technologies.

• The technology for APC will be low-cost and more performant due to COTScharacteristics and industrial technical evolution. This might be compared with thepresent situation of pilots working with the perturbed and unsecure VHF radio link andpassengers disposing of high-quality cellular phones.

The CNS/ATM community is focused on low-cost effective solutions, return on investments,COTS, but the reality is quite different since the CNS/ATM technology choice is influencedby specific “ICAO standard” products. In such a situation, it is quite difficult to get benefits ofthe large public market products. How will the CNS/ATM community support expensive costof specific products in the future ?

1.2. References

[ 1]: ADS it’s about time, C. Loisy, ESA

[ 2]: Future Satcom System Tailored for ADS in High Density Airspace, C. Loisy, ESA

[ 3]: FREER-1 (Airborne System) General Description - 04/96

[ 4]: FREER-1 User Requirements Document, Version 1.0 - 01/96

1.3. Web sites

Celestri http://www.mot.com/GSS/SSTG/projects/celestri/index.htmlFREER http://www.eurocontrol.fr/projectsGlobalstar http://www.globalstar.comICO http://www.i-co.co.uk/index.htmInmarsat http://www.inmarsat.org/inmarsat/index.htmlIridium http://www.iridium.comISA http://www.eurocontrol.fr/projectsMTSAT http://www.alcatel.com/space/page/mtsat.htmNext Generation Internet Initiativehttp://www.hpcc.gov/ngi/Skybridge http://www.skybridgesatellite.comTeledesic http://www.teledesic.com

1.4. Definitions and Acronyms

AAC Airlines Administrative CommunicationsACARS Aircraft Communications Adressing and Reporting SystemACTS Advanced Communications Technologies and ServicesADS Automatic Dependent SurveillanceAEEC Airlines Electronic Engineering CommitteeAIRCOM Airborne Communications


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AMCP WG-A Aeronautical Mobile Communications Panel Working Group-AAMSS Aeronautical Mobile Satellite SystemAOC Airlines Operational CommunicationsAPC Aeronautical Passenger CommunicationsATCC Air Traffic Control CentreATDMA Asynchronous Time Division Multiple AccessAtm Asynchronous Transfer ModeATM Air Traffic ManagementATN-OSI Aeronautical Telecommunication Network - OSI protocolATS Air Traffic ServicesB-ISDN Broadband-Integrated Services Digital NetworkBSU Beam-Steering UnitC-band Frequency band between 4 and 8 GHzCDMA Code Division Multiple AccessCNS/ATM Communication Navigation Surveillance, Air Traffic ManagementCOTS Commercial off-the-shelfCPDLC Controller-to-Pilot Data-Link CommunicationCMU Communications Management UnitDAP Downlink Aircraft ParametersDPLXR/LNA Diplexer/Low Noise AmplifierEEC Eurocontrol Experimental CentreESA European Space AgencyFANS Future Air Navigation SystemFCC Federal Communications CommissionFDMA Frequency Division Multiple AccessFMS Flight Management SystemGEO Geostationary Earth Orbit (around 22,250 miles)GSM Global System for Mobile communicationsHPA High-Power AmplifierICAO International Civil Aviation OrganisationIETF Internet Engineering Task ForceIOC Initial Operational CapabilitiesIP Internet ProtocolIPng/IPv6 Internet Protocol next generation/Internet Protocol version 6ISA Ipv6-Satellite-Atm projectISL Inter Satellite LinksKa-band Frequency range from 20 to 30 GHzKu-band Frequency range from 12 to 14 GHzL-band Frequency range from 1 to 2 GHzLEO Low Earth Orbit (from 500 to 1,000 miles)MEO Medium Earth Orbit (around 8,000 miles)MTSAT Multi-functional Transport SatelliteNASA National Aeronautics and Space Administration (US)PDU Protocol Data UnitPSDN Public Switched Data NetworkPSTN Public Switched Telephone NetworkQoS Quality of ServiceRFU Radio Frequency UnitRTCA Radio Technical Commission for AeronauticsSARP Standards and Recommended PracticesS-band Frequency range from 2 to 4 GHzSDU Satellite Data UnitSITA Société Internationale de Télécommunications AéronautiquesSTDMA Self organizing Time Division Multiple Access (VHF Data-Link mode 4)TDMA Time Division Multiple AccessUMTS Universal Mobile Telecommunication SystemVDL VHF Data-Link


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2. The present satellite system

2.1. INMARSAT

2.1.1. Overview

Inmarsat is an international organization, set up in 1979 to provide world-wide mobile satellitecommunications for the maritime community (International Maritime Satellite Organization).Today it has 81 member countries and is the only provider of global mobile satellitecommunications for commercial, emergency and safety applications on land, at sea and inthe air (International Mobile Satellite Organization).

Inmarsat Communication Systems offer a wide range of services including voice, fax anddata.

The Inmarsat satellites lie in geostationary orbit 22,223 miles (35,786 km) out in space. Eachof the 4 satellites (Inmarsat-3 series) covers up to one third of the Earth's surface and isstrategically positioned above one of the four ocean regions to form a continuous “world-wideweb in the sky”.Calls are beamed up to the satellite and back down to Earth, where special gateway landearth stations re-route them through the appropriate local or international telephone network.When someone calls an Inmarsat customer, it happens the same way - but in reverse.

At sea : for thousands of vessels, the Inmarsat satellites are the mainstay of theircommunications needs especially once a ship has sailed beyond the range of land-basedradio. Inmarsat mobile communications provide the maritime customers with direct-dialphone, fax, data, telex and electronic mail. Fleet monitoring, video conferencing, electronicdata interchange and weather forecasting are some of the applications helping to run theinformation superhighway along the sea-lanes of the world (Inmarsat-A, Inmarsat-B+M,Inmarsat-C).

On land : an Inmarsat-phone or data messager is ideal for people travelling in parts of theworld that terrestrial and cellular telephones cannot reach. Voice, data and fax is possiblethrough an Inmarsat-phone about the size of a laptop computer. From low-cost, pocket-sizedata messagers to high-speed satphones capable of beaming video images around theworld, the Inmarsat satellites keep people in touch, even in the remotest places on Earth(Inmarsat-A, Inmarsat-B, Inmarsat-C, Inmarsat-M).

In the air : until the advent of Inmarsat mobile satcoms, aviation was limited to radiocommunications, which suffered from the line-of-sight limitations of VHF and the unreliabilityand variable quality of HF radio. Inmarsat satellite links overcome these weaknessesbecause they are unaffected by distance or ionospheric conditions. On the flightdeck, thecrew is kept in touch with ground staff using Inmarsat voice and data communications. In thecabin, passengers can make phone calls or send faxes anywhere in the world from their seat.Meanwhile, on the ground, air traffic controllers use Inmarsat datalinks to monitor and directthe position of aircraft even when outside normal radar range (Aero-C, Aero-H, Aero-I, Aero-L).

2.1.2. The aeronautical system and its services

The Inmarsat Aeronautical satellite communications (satcoms) system provides two-way,digital voice and data communications for aircraft in order to meet the needs of flight-crew,cabin-staff and passengers. The system complies with the Standards and RecommendedPractices (SARPs) for Aeronautical Mobile Satellite Systems (AMSS) developed by theInternational Civil Aviation Organisation (ICAO).

The Inmarsat-Aero system consists of 3 basic elements which are Inmarsat satellites, groundearth stations and aircraft earth stations.


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The ground earth stations (GES) are fixed radio stations, which provide the interconnectionbetween the Inmarsat satellite system and the international telecommunications networks(including air traffic control centers). Communications between the GESs and the satellitesare conducted in the C-band (4/6Ghz). The interfaces with public and private data networksconform with CCITT recommendations X.25 and X.75, which define packet-data parameters,and will support ISO-8208-compatible data communications.

The aircraft earth stations (AES), are aircraft-installed radio sets capable of communicatingvia satelllite with a GES in the Inmarsat system. They operate in the L-band (1.5/1.6Ghz).The AESs conform to industry standards such as ARINC Characteristic 741 which describesone physical implementation of the Inmarsat system (e.g. SDU/RFU/HPA/DPLXR-LNA/BSU/antenna).

The different aeronautical markets that the Inmarsat Aeronautical service can serve havedifferent requirements for communication services.

The main features of the Aero-H (long/medium haul commercial aircraft) service arepresented below :

• Multiple, simultaneous telephone services,• Capable of supporting encrypted voice,• Facsimile at 4.8Kbit/s,• Real-time, two-way packet mode data at 600/1200bit/s and up to 10.5 Kbit/s,• Interfaces with international X.25/PSTN/PSDN networks,• Compatible with ISO 8208 inter-network standard,• Circuit-mode data option supports user-defined protocols,• World-wide service coverage at cruising altitude,• Complies with ICAO requirements to support safety and Air Traffic Control

communications,• Supports world-wide automatic position reporting and polling for Air Traffic Control, and

operations and management communication,• Supports ACARS/AIRCOM type messaging world-wide.

The Inmarsat Aero-H service gives aircraft world-wide multi-channel voice and datacommunications.

The voice facility operates in much the same way as a standard public telephone and can beused in the cockpit and cabin by flight crews and passengers alike.

In addition, Inmarsat Aero-H supports two types of data service : circuit mode and packetmode. The circuit-mode data facility provides an end-to-end communications path that allowsusers to apply their own protocols. This permits dial-up connections for equipment usingstandard modems and can support facsimile machines, computer modems and voiceencryption units.The packet-mode data service is based on the ISO 8208 inter-network standard for packet-switched data. Data terminals connected to the aircraft satcom equipment, which arecompatible with this standard, are capable of operating interactively with terrestrial X.25 datanetworks.

There are two levels of packet data services available : Data-2 (FANS 1 - Boeing) and Data-3(ATN-OSI/X.25).

The Data-2 service is a simplified packet-mode data service that lacks network functions. Ithas no adressing capabilities and is used to support connectionless characters-orientedACARS/AIRCOM type services. It can however support bit-oriented applications when usedwith the special protocols described in ARINC Specification 622 (e.g. ATS two-way datalinkmessages and ADS reports).

Data-3 is the fully-8208 and ICAO SARPs compliant packet data service, complete withnetwork-layer and standardized interfaces (i.e. ISO-8208 and X.25).


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The Data-3 service gives the user many facilities, including :

• Any private or public network can be accessed,• The aircraft can have multiple active connections e.g. with an airport, an airline network

and a weather office, etc...,• Different messages and data can be given different priority, e.g. distress data will be

given higher priority than a news broadcast,• ICAO AMSS and ATN requirements are satisfied.

A set of four basic RF transmission channels are needed to accommodate the full range ofvoice, fax and data services. Any given channel can pass information in one direction only,which means that a pair of voice channels must be assigned, for simultaneous two-way voicecommunications. A basic description of the four basic channel types follows :

• P-channel (packet-mode channel) - a time-division-multiplexed (TDM) channel used forground-to-air signalling, control and data communications,

• R-channel (random access channel) - used for air-to-ground signalling and datacommunications,

• C-channel (circuit-mode channel) - used to provide full-duplex voice, fax or circuit-modedata communications,

• T-channel (time division multiple-access channel) - the channel is the air-to-ground datacommunications channel used for the transmission of longer messages (e.g. ADSapplication).

The potential applications that can be supported by the Aero system concern flight-crew,cabin-crew and passengers applications.

1) Flight-crew applications include communications via satellite for Air Traffic Services,flight operations and other airline purposes. These applications can be initiated from the air orthe ground.

Satellite communications can allow Air Traffic Services and operational support services tobe initiated automatically or when required by the flight crew.

They include :− Direct two-way datalink communications between the pilot and the air traffic controller to

pass information such as clearances or traffic information...,− Position reporting using Automatic Dependent Surveillance (ADS). Air Traffic Control

instructs an aircraft to report specified data at regular intervals.

Flight operations which can benefit from satcoms include :− ACARS or AIRCOM data transmission when out of terrestrial VHF range,− Aircraft System monitoring (e.g. engine and system health monitoring...),− En route flight plan and weather updates,− Direct voice contact with company operations for immediate advice on onboard problems.

2) Cabin-crew applications focus on communications for airlines administrative purposesand can be air or ground initiated :− Crew scheduling and e-mail,− Catering management and flight documentation,− Medical support for emergency.

3) Passenger applications include :− Telephone calls,− Fax,− Connection of PCs to ground network and databases,− Hotel and rental car reservations, flight confirmations or reservations.


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3. Satellite projects compliant ICAO

3.1. The Satellite Data Link System (SDLS)

3.1.1. Presentation

The European Space Agency (ESA) commissioned recently a study to investigate thefeasibility of a low cost aeronautical Satellite Data-Link System (SDLS) to provide for theneeds of Air Traffic Services such as safety-related communications over continental areaswith high air-traffic density. The SDLS target area is the west European continent.

The SDLS study is placed in today’s context which sees the first generation of AeronauticalMobile Satellite System (AMSS) being gradually but restrictively put into service in oceanicairspaces with low air-traffic density (cf. ADS-Europe project). In other words, this study isaimed to identify and overcome the weaknesses encountered during the ADS-Europe trials,in providing low cost solutions.

The design of a future system will be dedicaced to ATS to better accommodate the veryspecific and demanding ATS requirements. Nevertheless, the main objective of the SDLSremains the optimization of ADS (Automatic Dependent Surveillance).

But, why ATS only and not AOC, AAC and APC services ?Safety of flight on one hand and commercial communications on the other, tend to haveopposite requirements profiles :− Availability and grade of service are dominant for safety-related services, cost having a

lower priority; it is exactly the opposite for commercial services.− Bandwidth requirements are and will remain low for safety-related services (50bps). The

commercial services will require more bandwidth due to astounding growth of theInternet/multi-media.

The supplementary requirements will be the economically affordable provision of AirlineOperational and Administrative Communications.

The SDLS will be close but not fully compliant with the ICAO ATN standards. For instance, amodification will be necessary to replace the transmission of the ISH-PDUs (IntermediateSystem Hello - ATN : surveillance mode of a link) by the aircraft position report. The interestis now well recognized, to also provide non-ATN specific services, which take advantage ofcharacteristics of the current comms (such as broadcast for satellite and VHF for datalink).The dividing line between ATN compliant and non ATN-specific services is to be drawnbetween those applications for which data transmission delay is not critical but data integrityis (example of flight plan data between the on-board and the ATM computers), and those forwhich short delays and high refresh rate is critical (Aircraft Position Reporting or Downlinkingof Airborne Parameters).

The current data-only AMSS features a “random access” function whereby a “called channel”(R-channel of the Inmarsat system) is dedicaced to this function and shared among themobiles in a “random access” mode. This access mode generates collisions.By contrast in a polling scheme, mobiles are individually addressed in a sequential mannerand invited to transmit their data in individualised time windows. This removes the risk ofcollision but is of course inefficient if mobiles are polled whenever they have nothing totransmit.

The SDLS capability to support automated Aircraft Position Reporting (APR) with refresh rateof few seconds, associated with the polling scheme for communication with mobiles, isanalogous to SSR Mode-S datalink, whereby an aircraft is interrogated every 4 to 10 secondsfor identity confirmation. It is logical to design SDLS specific services formats and protocol forcompatibility with those defined by ICAO for Mode-S specific services.


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The SDLS ATS Data Link applications to be offered, can be categorised in four groupings,according to their main purposes - information exchange between :

• pilot and controller (CPDLC...),• ATC system and pilot (pilot information...),• aircraft systems and controller (Aircraft Position Reporting, Downlink Aircraft

Parameters...),• ATC system and aircraft systems (downlink of FMS data, trajectory/route negotiations...).

The SDLS will incorporate technical provisions of real-time, full duplex “cockpit voice”capability for emergency voice communication.

ATS comms Quality of Service requirement reflects several attributes. Of prime importanceare service availability, data integrity and guaranteed transmission time. Concerning serviceavailability, a performance figure not lower than that required for the availability ofsurveillance data from RADAR is a reasonable objective.

A reasonable assumption in terms of SDLS suitable network architecture may be to derive itfrom that of the present Civil Aviation decentralised architecture which allows for the localmanagement of the communication resources at the ATC centers. Each ATCC wouldmanage a SDLS local network by polling aircrafts in its control responsibility area for positionreporting and transmission of data. These local networks would interface at the local ATCCswith the ATN ground infrastructure to achieve full connectivity. Finally a decentralizedarchitecture allows each ATCC to possess its own access to satellite(s), via its own GES.

Concerning space segment, some preliminary assumptions must be made, regardingeconomical considerations :− an aeronautical service providing ATS cannot afford an independent dedicaced

constellation of satellites. Satellite platforms must be shared with other missions.− the system must share parts of communication payloads with other mobile services, in so

far as the required bandwidth and power would be exclusive use by the ATS system.

Two links are used for transmissions :− the forward link from ground to aircraft via satellite with CDMA/TDM access scheme and,− the return link from aircraft to ground via satellite with CDMA/TDMA access scheme.

The service availability requirements will dictate redundant satellite links in order to offercontinuity of service. This could be organized, in the ground to air direction, in such a waythat each aircraft would permanently receive its data from the ATC center through twosatellites simultaneously. In the air to ground direction, an appropriate scheme would be thataircraft transmission is picked up in parallel by the two satellites.

The LEO and GEO satellites approaches will be equaly discussed in the study.

The ESA system contemplated in the SDLS study should be designed for compatibility withthe Aeronautical Earth Station (AES - low cost approach) characteristics specified by ICAOfor data-only AMSS. The AES communicates with ground station via space segment. TheAES is composed by sub-systems as the omni-directional antenna, the diplexer/Low NoiseAmplifier, the Radio Frequency Unit, the Satellite Data Unit, the Automatic DependentSurveillance Unit and the GPS Antenna and Receiver, etc. The SDLS AES shall bephysically and logically interconnected to on-board avionics via ARINC 429 buses.

The use of a Ku-band feeder link makes it possible to locate Ground Earth Stations (GES)directly at the ATC centers. The GES is the gateway between ground segment and spacesegment. Safety and reliability are preserved at the ground segment thanks to the fullyredundancy of GES. Each single GES operates with only one satellite. One antenna isnecessary per satellite. The GES assures the transmission quality, plans the resourcesneeds, manages and routes information between the end-users and complies the interfaceswith other subnetworks type ATN. The interfaces with the ground network shall provide a datapacket transmission service conforming to ISO 8208 or X.25 standard and protocol.


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Users Aeronautical Earth Station are logged-on to one Ground Earth Station at a time. Hand-over from one network to the next is operated through explicit log-off and log-on to the newone. At the first log-on the user is allocated a local address in a network.

To minimize cost, consideration is given to re-use the ESA-developed Land MobileCommunication Technology known as Mobile satellite Business Network. This MSBN isaimed to provide an effective satellite communication system capable of meeting thecommunication requirements associated with management of vehicle fleets over Europe.The basic services provided are real time voice and data transfer, with others applicationsincluding data messaging, voice messaging and fax.

Assuming a successful outcome of the on-going SDLS feasibility study, a detailed systemdesign phase is expected to follow which would include the implementation of ademonstration system. Performance evaluation programme will feature in-flightdemonstrations using satellites (L-band payloads) and the aviation community would begiven the opportunity to critically access SDLS, through field trials, in comparison with othermeans of surveillance and communication (SSR Mode-S, VHF Data-Link and AMSS).

3.2. IRIDIUM’s LEO-satellite system

3.2.1. Overview

The Iridium system will enable subscribers with hand-held mobile terminals to conduct two-way voice and data communications from anywhere in the world with similarly-equippedsubscribers or with telephone users.

The system will have four basic components: satellites, mobile transceivers, ground-basedsatellite-control facilities, and gateway earth stations. The space segment will consist of aconstellation of 66 satellites in Low-Earth Orbit (LEO), networked together and providingcontinuous global coverage. The Iridium system will use GSM-type technology to linkmobiles to the satellite network. The satellites will orbit above the earth at an altitude of 420nautical miles (780km). Each satellite will have radio links with adjacent Iridium satellites andwith gateway stations and will use an array of spot beams for transmission to end-users hand-held mobile transceivers1. The gateways will interconnect the Iridium constellation to thePublic Switched Telephone Network (PSTN). This network function makes communicationspossible between Iridium telephones and any other telephone in the world.

The Iridium system is being funded by Iridium Inc., a diverse international consortium oftelecommunications and industrial companies. Motorola is the prime contractor to Iridium Inc.for the procurement of the Iridium system.

August, 1997 : one-third of the planned 66-satellite constellation is placed into orbit. TheIridium system is expected to go into service in 1998.

The Iridium system will employ a combination of Frequency Division Multiple Access andTime Division Multiple Access (FDMA/TDMA) signal multiplexing to make the most efficientuse of limited spectrum. The Ka-Band (19.4-19.6 GHz for downlinks; 29.1-29.3 GHz foruplinks) serves as the link between the satellite and the gateways and earth terminals. The L-Band (1.616-1.626 GHz), serves as the link between the satellite and Iridium subscriberequipment.The intersatellite links are essential for providing truly global communication coverage willtake place in the Ka frequency band between 23.18 and 23.38 GHz.

Iridium will also address the whole aeronautical market, both the narrow-body and long-haulmarket. Aeronautical Iridium services will provide essential voice, facsimile, and dataservices to travelers on commercial and business aircraft.

1 In a LEO satellite cellular system, the satellites are moving much faster that the humans, so their velocity requires userhandoffs as one satellite drops towards the horizon and another rises.


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Compact and lightweight Iridium units are designed to complement the existing aeronauticalcommunications configuration and offer passengers convenient global access totelecommunications. In addition to passenger communication services, Iridium plans to offera safety-related satcom service.

3.2.2. The aeronautical services

Iridium is intended to provide both safety (ATS & AOC) and non-safety (AAC & APC)services across all authorized frequencies. The four services will share the same frequencyband and a multi-level priority, precedence and preemption scheme will ensure that safetycommunications always take priority in the Iridium system (i.e ATS has priority over AOC,and AOC has priority over AAC/APC).

The Iridium system (ATN-OSI compliant) will be a subnetwork wherein the airborne router isprovided with a data port (ISO8208 on an ARINC429 Williamsburg interface) that allows theATN traffic to traverse the system and exit the gateways into, for example, X.25/X.75 groundnetworks connected to the ATN. It is designed to be a (transparent) packet data subnetworkthat is completely transparent to the ATN-OSI traffic.

Iridium expects to have high availability, better than HF and other satellite-basedcommunication systems.Iridium is participating in a range of regulatory activities to ensure its service is approved forsafety-related satcom service. Earlier in 1997, the ICAO's AMCP WG-A and RTCA's SpecialCommittee 165 determined that next-generation satellite communication systems, such asIridium, could feasibly be used for aeronautical safety services (definition of latency time,system availability and reliability, data integrity, and service continuity for satellitecommunication systems).Iridium is involved with the aviation standardization bodies such as ARINC/AEEC, whichrecently adopted ARINC 761 - the LEO/MEO characteristic. They are also talking to SITA fortheir requirements.

The Iridium radio will propose the voice, fax, PC-data and packet-data services to the cabinpassengers. To do this, they expect almost every commercial air transport and militarytransport aircraft to have some form of LAN that is consistent with ARINC Standard 628 andARINC Characteristic 746, or their equivalent. Smaller airplanes may have dedicatedhandsets. There may be other means of passenger communications provided on board theaircraft by its operator.

Bandwidth on-demand is being looked at as a future option.

A conference call capability is foreseen, allowing multiple parties to engage in two-way, Air-to-Air and Air-to-Ground, half-duplex conversations, in much the same way as VHF COMMworks today. This feature may become intrinsic to Iridium phase 2 starting in 2003. In themeantime (Iridium phase 1), this service would have to be provided by a service provider.

They do plan to offer direct Air-to-Air communications (voice and packet-data) betweenaircraft (e.g. aircraft_1 to satellite constellation to aircraft_2).

Iridium phase 1 (1998-2003) will not support dynamic bandwidth allocation functions becausethe company is keen to maximize the efficiency of the spectrum that it is licensed to use.Iridium phase 2 may offer these functions (but probably not with Atm and/or Ipv6...).

The current development status is that AlliedSignal is developing single and multi-channelavionics products. Iridium expects to certificate the multichannel product for voice and packetdata in April 1999 for safety and non-safety use.

They have 39 of 66 satellites in orbit, and 5 are launched per month. The constellation andthe ground equipment will all be in place by March 1998. Engineering trials will occur in Aprilthrough to June 1998. Commercial trials will run July through to September. Commercialservice will start in September 1998, and Aeronautical safety services in April 1999.


- 11 -

3.3. GLOBALSTAR’s LEO-satellite system

3.3.1. Overview

Globalstar system is a satellite-based, wireless telecommunications system designed toprovide voice, data, fax, and other telecommunications services to users worldwide. Users ofGlobalstar will make or receive calls using hand-held or vehicle mounted terminals similar totoday’s cellular phones. Calls will be relayed through the Globalstar satellite constellation, to aground station, and then through local terrestrial wireline and wireless systems to their enddestinations.

Globalstar satellites do not directly connect one Globalstar user to another. Rather, they relaycommunications between the user and a gateway. The party being called will be connectedwith the gateway through the Public Switch Telephone Network (thus maximizing the use ofexisting, low cost communications services) or back through a satellite if the party is anotherGlobalstar user.

Space Systems/Loral, a leading manufacturer of commercial telecommunications satellites,is the prime contractor for the Globalstar space segment. Space Systems/Loral (SS/L) willperform the construction of Globalstar’s satellites in conjunction with various other membersof the Space Systems Alliance (comprised of Aerospatiale Societe Nationale Industrielle,Alcatel, Alenia spazio, Daimler-Benz Aerospace and Finmeccanica) and with Hyundai.

56 Globalstar satellites will be placed into low Earth orbit, 48 of which will be operational, witheight on-orbit spares. The satellites will be placed in eight orbital planes of six satellites eachwith a 1,414 kilometer circular orbit. Globalstar will commence initial commercial operationsvia a 24-satellite constellation in 1998. Full 48-satellite coverage will occur in the first half of1999.

To achieve low cost, reduce technological risk and accelerate deployment of the Globalstarsystem, Globalstar’s system architecture uses small satellites incorporating a well-establishedrepeater design that acts essentially as a simple "bent pipe" (simple, existing, proven satellitetechnology, no on-board processing, no inter-satellite links), relaying signals received directlyto the ground. All the system’s call processing and switching operations are on the ground,where they are accessible for maintenance and can benefit from continuing technologicaladvances. In addition, the CDMA digital technology selected by Globalstar promotes efficientuse of satellite resources.

The C-Band (6.875-7.055 GHz for downlinks, 5.091-5.250 GHz for uplinks) serves as the linkbetween the satellite and the gateways (feeder links) and earth terminals. The L-Band (1.610-1.626 GHz), serves as the link between the Globalstar subscriber equipment and satellite,and the S-Band (2.4835-2.500 GHz) between the satellite and Globalstar subscriberequipment (user links).The satellite antennas are of a phased array design that projects a pattern of 16 spot beamson the Earth’s service, covering a service area, or "footprint" of several thousand kilometersin diameter.

3.3.2. The aeronautical servicesAeronautical services compliant ICAO are foreseen, but there is no accessible information forthe time being.

3.4. ICO’s MEO-satellite system

3.4.1. OverviewICO Global Communications was established in 1995 as a private company with its origins inInmarsat. ICO is creating a satellite-based mobile communications system designed primarilyto provide services to handheld phones. The system will offer digital voice, data, fax and asuite of messaging services worldwide. The company will begin operation in the year 2000.


- 12 -

ICO is owned by telecommunications service providers and network operators. The companyis working with world-class industrial partners to develop its system and with the leadingsuppliers of user terminals to provide the broadest possible choice for its customers.

ICO's system will consist of a space segment and a dedicated ground network.

The ICO space segment will comprise 10 operational satellites and 2 in-orbit sparesoperating in middle Earth orbit (MEO) at an altitude of 10,355km. Each satellite will coverapproximately 30 per cent of the earth's surface at a given time. The orbital pattern isdesigned for significant coverage overlap, ensuring that usually two or more satellites will bein view of a user and a ground station at any time.

The satellites will communicate with ground networks through the ICONET. The ICONET willconsist of 12 earth stations or satellite access nodes (SANs) located around the globe, linkedby a backbone terrestrial network. The SANs will comprise three main elements :− five antennas, with associated equipment to communicate with the ICO satellites;− switch to route traffic within the ICONET and other terrestrial networks, in particular the

Public Switched Telephone Network (PSTN);− and databases to support mobility management.

Each SAN will contain a database to hold details of user terminals currently registered to thatSAN.

Feeder link antennas will support the link between the satellites and the SANs. At any time,each satellite will be in direct contact with between two and four SANs. Before a satellite fallsoutside the line of sight of one SAN, contact will be established with another SAN. This SANwill then track the satellite whilst it is in its line of sight.

Links between individual users and satellites will be established via service antennasmounted on each of the satellites. The use of multiple service link beams on each satellitewill also allow frequency re-use and will increase the efficient use of spectrum allocation.

The satellites will operate in S-band and C-band using digital onboard processing and timedivision multiple access (TDMA) to handle up to 4,500 simultaneous phone calls per satellite.

Spectrum requirements :− The ICO system services links will operate in the 2 GHz band (the links between the

satellite and handheld/user terminal). Specifically, mobile satellite service systems willhave access to 1.98-2.01 GHz for uplinks and 2.17-2.20 GHz for downlinks;

− ICO has chosen to operate in the 5 GHz and 7 GHz bands for feeder link operation (theconnections between the satellites and gateway earth stations/SANs). ICO will use feederlink in the 5.15-5.25 GHz band (Earth to space) and in 6.975-7.075 GHz (space to Earth).

The fragmentation of standards and the remaining unserved geographical areas represent anopportunity for satellite phones. ICO does not believe that a satellite handheld phone servicewill ever be deliverable at prices competitive with those of well-designed terrestrial systems.But satellite phone will form an ideal complement service in regions where the terrestrialservice is not compatible with the user's home service, or where there is simply no terrestrialcoverage.

ICO user terminals will include, among others, handheld mobile telephones which, in outdoorenvironments, will offer services similar to normal cellular phones. The ICO system will routecalls from terrestrial networks through ground stations which will select a satellite throughwhich the call will be connected. Calls from a mobile terminal will be routed via the satelliteconstellation to the appropriate fixed or mobile networks or to another mobile satelliteterminal.The basic handheld phones will be dual-mode, capable of working with both satellite andcellular/PCS networks. The ICO handheld phone is planned to have optional featuresincluding external data ports and internal buffer memory to support data communication,messaging functions, and facsimile.


- 13 -

ICO services are expected to be used by international and domestic cellular users who roamoutside areas covered by compatible cellular networks from business, industry andgovernment organisations, transportation, aeronautical, maritime, media and other specialistsectors as well as residents of rural and remote areas lacking adequate localtelecommunications infrastructure.

ICO will supply service to customers through a distribution chain of national wholesalers,franchisees and retailers.


ICO plans to provide global aeronautical communications for safety of flight, operational andcommercial applications.

The aeronautical segment development at ICO is primarily focused on providing state-of-the-art communications and information services to commercial and corporate passengers.While the majority of business passengers today seldom use the seat back phone for morethan simple voice communications, ICO believes that in the future data bearer servicessupporting fax, email, and file transfer using packet switch communications will becomeincreasingly important to the business user. The ICO service platform will support a variety ofcommunications and supplementary services. While ICO’s interest in the Aeronauticalsegment development is not confined to commercial use, support for safety and operationalapplications will be initially provided via the Inmarsat or existing VHF Air-to-Ground links.

The ICO AeroPhone service concept will provide aircraft with simultaneous two-way, digitalvoice and real-time data communications world-wide to meet the needs of flight crew, cabinstaff and passengers.The voice facility will operate in much the same way as a standard public telephone can beused in the cockpit and cabin by flight crews and passengers alike. The ICO system willsupport data services. The circuit-mode data facility will provide an end-to-endcommunication path that allow users to apply their own protocols. This will permit dial-upconnections for equipment using standard modems and support fax machines, computermodems and encryption units. The ICO service platform will support circuit switched dataspeeds from 4.8 to 38.4 kbps.

ICO-compatible satellite communications equipment (steerable-high-gain antenna andsuitable avionics) should be installed on-board aircraft in order to access the AeroPhoneservice. Other peripherical equipment such as telephone sets, fax machines and personalcomputers interface to the ICO AeroPhone RF equipment via a central CommunicationsManagement Unit (CMU).

3.5. MTSAT’s GEO-satellite system

3.5.1. Presentation

Faced with the constant growth in air transport in south east Asia and the specialgeographical factors in this region, the Japanese Ministry of Transport represented by theJapanese Civil Aviation Bureau (JCAB) has opted for a full-scale implementation of theCNS/ATM (Communication, Navigation, Surveillance/Air Traffic Management) concept. Thisconcept is based on the use of a satellite in order to overcome the limits imposed bytraditional terrestrial navigation aids.

The offered services will comply with the Standards and Recommended Practices (SARPs)for Aeronautical Mobile Satellite Systems (AMSS) developed by the International CivilAviation Organisation (ICAO) - like the Inmarsat Aero system.


- 14 -

The Multi-functional Transport Satellite (MTSAT) has two main objectives for Japanese CivilAviation Bureau (JCAB) and Japan Meteorological Agency (JMA). The mission for JCAB isan aeronautical traffic control communication function between MTSAT and the airplanes.With JMA the objective is for a meteorological function to gather data related to clouds andwater vapor temperatures for terrain and sea surfaces.

Japan is the first country to use a satellite system in order to improve the management of airtraffic. MTSAT will comprise a spatial segment which eventually will consist of twogeostationary satellites (42,164 km) and an earth segment. The system will be operational in1999.

The aeronautical mission of the program, complemented by a meteorological mission, willdeliver the three CNS-based (Communication, Navigation and Surveillance) servicesdestined to improve air traffic management :

• Voice and data exchange between aircraft and control tower (packet-mode at 9600 bps).Air-traffic communications will use the L-band and the Aeronautical Mobile SatelliteService (AMSS) protocol which is specific to mobile telecommunications. Links betweenthe earth segment and satellite segment will use the Ku and Ka-bands.

• Navigation by satellite. This function will be used to create the geostationary complement

to GPS, making the MTSAT project the Japanese GNSS1 project. Using GPSaugmentation concepts, the MTSAT Satellite-based Augmentation System (MSAS) willprovide seamless precision air navigation capability all over Asia. It is expected toimprove the safety and predictability of flights and make savings in operating costs.

• Air traffic surveillance. This will make use of the ADS (Automatic Dependence

Surveillance) system to achieve higher-quality control. Links between the earth and thesatellite will use the Ku-band and Ka-band, links between the aircraft and the satellite willuse the L-band.

Alcatel is a major contributor to the MTSAT project, thanks to its expertise in space and inaeronautics. Alcatel has full responsibility for the telecommunications payload of the MTSATsatellite. The company is also playing a leading role with its partners (System-Space/Loral,Toshiba and Mitsubishi Electronic Corporation) in the aeronautical mission and in theproduction of traffic and earth control stations.

Redundancy deliberately designed into the space segment and earth segment reflects thedetermination of the Japanese aviation authorities to provide an operational system thatsatisfies every aspect of the ICAO requirements in terms of reliability and accuracy. In orderto prevent any risk-taking and to meet specifications that often impose important constraints,advanced solutions always embody proven technologies.

The multi-mission MTSAT project will allow the Japanese authorities to use their airspacemore flexibly and more efficiently, improve flight safety and lead to operational savingssignificant for air carriers and navigation service providers.


- 15 -

4. Broadband satellite systems proposals

Recently there have been a lot of broadband Ka-band satellite system proposals. Most ofthem use “Atm-like” transmission, on-board processing and inter satellite links. “Atm-like”means packets of fixed size but not as 53 byte Atm cells.

4.1. TELEDESIC

4.1.1. Overview

Using a constellation of several hundred low-Earth-orbit satellites, Teledesic will create aworldwide network to provide affordable, "fiber-like" access to telecommunications servicessuch as broadband Internet access, video-conferencing, high-quality voice and other dataneeds. Teledesic will propose "bandwidth on demand," allowing users to adjust the channel’sbandwidth to match traffic volumes and applications.

Teledesic is backed by Craig McCaw, Chairman of McCaw Cellular, and Bill Gates,Chairman of the Board of Microsoft Corporation. April 1997 - Boeing became an equitypartner in Teledesic and the prime contractor for the company’s global, broadband "Internet-in-the-sky." Boeing2 will design, build and launch the Teledesic Network.

Teledesic’s satellite system will consist of 288 non-geostationary satellites divided into 12orbital planes, each with 24 satellites. Teledesic satellites will operate at a low altitude, under1,400 kilometers.

The Teledesic constellation design will support the network requirements for quality, capacityand integrity. The only feasible frequency band internationally allocated to Fixed SatelliteService which may offer substantial bandwidth to provide high-quality, high-speed wirelesschannels and meet Teledesic’s requirements is the Ka-band. The Teledesic constellation willuse a high elevation mask angle to mitigate rain attenuation, terrain blocking, and otherterrestrial systems. A low orbit altitude is used to meet the requirements for low end-to-enddelay and reliable communication links that use small, low-power terminals and antennas.The combination of low altitude and high elevation mask angle results in a small coveragearea per satellite and a large number of satellites for global coverage.

The Teledesic Network will offer high-capacity, "bandwidth-on-demand" through standard andmobile user terminals. Channel bandwidths will be assigned dynamically and asymmetrically,and will range from a minimum of 16 Kbps up to 2 Mbps on the uplink, and up to 28 Mbps onthe downlink. Teledesic will also be able to provide a smaller number of high-rate channels at155 Mbps to 1.2 Gbps for gateway connections (gigalink terminals) and users with specialneeds.

The Network will use fast packet switching technology based on the Asynchronous transfermode (Atm) technology. All communication will be treated identically within the network asstreams of short fixed-length packets that carry the digitally-encoded voice or data.Conversion to and from the packet format takes place in the terminals. The fast packet switchnetwork combines the advantages of a circuit-switched network (low delay, digital pipes), anda packet-switched network (efficient handling of multi-rate and bursty data). Fast packettechnology is ideally suited for the dynamic nature of a LEO network. Each satellite in theconstellation is a node in the fast packet switch network, and has intersatellite communicationlinks with adjacent satellites.

The Network will use a combination of multiple access methods to ensure efficient use of thespectrum. All communication will take place between the satellite and the terminals during anassigned time slot (TDMA). Within each time slot, terminals will use Frequency DivisionMultiple Access (FDMA) on the uplink and Asynchronous Time Division Multiple Access(ATDMA) on the downlink.

2 Although Boeing is a partner in Teledesic, no new “FANS package” is envisaged.


- 16 -

Teledesic will operate in the Ka-band :− the 28.6 - 29.1 GHz (uplink) and 18.8 -19.3 GHz (downlink) band segments for its service

links,− and the 27.6-28.4 GHz (uplink) and 17.8-18.6 GHz (downlink) band segments for its

"gigalink" gateway terminals.

Teledesic will also use inter-satellite links to interconnect each satellite with eight othersatellites in the same and adjacent planes. The ISL will operate in the 59.5-60.5 GHz and62.5-63.5 GHz bands.

Teledesic does not intend to market services directly to end-users. Rather, it will provide anopen network for the delivery of such services by others. The Teledesic Network will enableservice providers in host countries to extend their networks, both in terms of geographicscope and in the kinds of services they can offer. Ground-based gateways will enable serviceproviders to offer seamless links to other wireline and wireless networks, such as the Internet.

Teledesic will provide twenty-four hour seamless coverage to over 95% of the Earth’s surfaceand almost 100% of the Earth’s population. Teledesic plans to begin service in the year 2002.


The Teledesic system will offer a mobile service to aircraft up to 19,000 meters at InitialOperational Capabilities (IOC). This service could be used for Aeronautical PassengerCommunications (APC) applications. If the system proves to be secure enough, the servicescould “possibly” be expanded to Air Traffic Control/Air Traffic Management (ATS)applications. There will be no ICAO compliance with The Teledesic system.

The mobile service will be offered within the same overall band allocated for the fixedservice, with channel assignments allocated dynamically, and priorities assigned asrequested, assuming availability.

Teledesic will offer a service with high QoS including high availability and low latency. Thesystem will propose a range of priorities by which a high priority service may request and begranted a "guaranteed" circuit-like connection and a guaranteed minimum delay.

The availability is driving the overall system design and Teledesic is planning sufficient linkmargin to assure 99.9% or higher reliability in all but the most humid regions of the world.

Teledesic service objectives will not impose a requirement on their network for nativemulticast capabilities. The network will however be compatible with a variety of "non-native"implementations of multicast. It will offer a "cell-cast" and a "footprint-cast" capability.

The satellite payloads will constitute fully capable network "nodes" with switching from anyinput, i.e., uplink or crosslink, to any output, i.e., downlink or crosslink.

With respect to the range of services mentioned earlier, Teledesic is targeting only thepassenger services that will require high bandwidth and low latency, i.e., current andenhanced IP-like services. According to Teledesic, the narrowband requirements or delaytolerant services associated with reporting functions could probably be more economicallyserved by another technique more cost-effectively, and the very high reliability aircraft controlfunctions may require even higher reliability than Teledesic, or any other wirelesscommunications medium can offer.

Teledesic intends to use its own "connectionless" protocol within its own network and providean interface at the user equipment level to interconnect to a complete set of existing andproposed protocols that will be in use in their IOC timeframe (2002). No more details aboutthe protocols used and no trace of Atm and/or Ipv6...

The Teledesic system will offer mobile service at "on-demand" data rates from 16 Kbps up toat least 2 Mbps, as requested by the specific applications.


- 17 -

Teledesic is currently in what would be considered preliminary design, with a projectedcontract signing with major suppliers anticipated within 4 months. When they have completedthis phase of the program, they will have more time to engage in technical dialog withpotential users such as Eurocontrol.

4.2. CELESTRI

4.2.1. Overview

Motorola’s first satellite business, Iridium, is a voice and paging system. The second system,M-Star3, is a high-bandwidth system that will provide data to corporations. The Celestrisystem is the third major satellite venture for Motorola. The latter is expected to offer a widerange of real-time broadband communication services by the year 2002 and compete withthe Teledesic venture proposed by Microsoft’s Bill Gates and cellular phone pioneer CraigMcCaw.

The Celestri System will combine geosynchronous high-earth orbit satellites (Millenium4) andlow-earth orbit satellites with earth-based control equipments and interfaces. The GEOsatellite constellation orbiting at 22,300 miles (36000km) above the earth, would providebroadcast services such as television. A constellation of 63 LEO satellites, orbiting at 900miles (1450km) above the earth, would provide telecommunications carriers, businesses andconsumer customers instant access to a broadband network infrastructure and truebandwidth-on-demand throughout the world.

Each LEO satellite would contain all of the hardware necessary to route communicationstraffic through the network, including Earth-to-space, space-to-Earth and space-to-spaceconnections. Earth-based control equipment would include terrestrial-based networkinterfaces to telecommunications infrastructures, the Internet, corporate and personalnetworks, entertainment networks and residences. This equipment will seamlessly interfaceto existing computers, television (HDTV), and Local Area Networks (LANs) and Wide AreaNetworks (WANs).

The Celestri architecture will allow integrated systems to support four classes of service forthe marketplace. These types of service are :

• point-to-point, real-time symmetric connection services ranging from 64 kbps to 155Mbps;

• point-to-point, bursty asymmetric services, in which each direction of communicationuses varying amounts of bandwidth as needed, ranging up to 16 Mbps;

• broadcast and multicast services using variable service areas and communication rates;• interactive and integrated broadcast and real-time response services.

The transmission mode will be “Atm-like”.

This architecture will allow for the use of relatively small, low power and low cost earthterminals.

3 Motorola has proposed M-Star which is a broadband satellite system consisting of a 72 satellite LEO. The system intendsto use a new area of spectrum in the 36-51.4 Ghz frequency band - known as millimetre wave band frequencies.The company plans to offer two types of services : firstly, a voice and data communications offering to fixed terminals forbusiness users; and secondly, a trunking service that would be aimed at mobile cell service operators who want to tie theirlocal networks into the global telecoms infrastructure, a practice called "backhauling".

4 The Millenium GEO proposal by Motorola consists of 4 satellites to provide broadband capacity to third-party retailers.Motorola requests use of 750 MHz of spectrum in the 28.35-28.6 and 29.5-30.0 GHz bands for service uplink operationsand 750 MHz of spectrum in the 18.55-18.8 and 19.7-20.2 GHz bands for its service downlink operations. It also requestsauthority for inter-satellite links to connect the satellites in the 59.5-60.5 and 62.5-63.5 GHz bands.Motorola proposes to support residential and business communications. It proposes to offer "bandwidth on demand" whichallows subscribers to pay only for the spectrum resources that they need.


- 18 -

Motorola requests 750 MHz of spectrum for uplink and downlink transmission in the Ka-band.The service and gateway links of the Celestri LEO System will operate in the 18.8-19.3 GHzand 19.7-20.2 GHz bands (space-to-Earth) and the 28.6-29.1 GHz and 29.5-30.0 GHz bands(Earth-to-space). The system will use optical inter-satellite links to interconnect the satellitenetwork in space. Motorola also requests 2 MHz in the 50-70 GHz range for its inter-satellitelinks.


The Celestri System is intended to provide fixed rather than mobile service. In this way, theyclaim to assure spectrum sharing through spatial diversity.

According to Celestri, although aircraft communications sounds intriging and is technicallypossible, it poses a problem of possible interference with terrestrial sites on the downlink oreven interference with other satellites on the uplink.

The aeronautical services do not appear to be at first sight, a practical application for theCelestri System. However, the discussion remains open...

4.3. SKYBRIDGE

4.3.1. Overview

Alcatel Space is also actively involved in Atm over Satellite projects.

February 1997 - Alcatel Space, a unit of Alcatel Alsthom and SkyBridge’s parent companyannounced the filing with the Federal Communications Commission of an application tolaunch and operate a global network of non-geostationary orbit satellites to provide a widerange of data, voice, and video broadband services in the Fixed-Satellite Service. Theproposed system will employ a constellation of 64 satellites orbiting at an altitude of 1457km.

June 1997 - Alcatel Alsthom and Loral Space & Communications Ltd formed a strategicpartnership to jointly develop, deploy and operate high speed global multimedia satellitenetworks that will bring high-bandwidth services to businesses and to consumers.The agreement includes cross investments in Alcatel’s low-Earth-orbiting satellite-basedSkyBridge project and Loral’s geostationary satellite-based CyberStar5 project.

Services will be introduced in the market through dedicated geostationary satellites in 1999and a constellation of LEO satellites in 2001.

Geostationary systems are well suited for the delivery of broadcast and a large variety ofasymmetric services. Low earth orbiting systems, due to their low propagation time, are veryefficient for the delivery of highly interactive services. LEO constellations provide a globalcoverage while geostationary systems can be targeted to regional markets.

Thanks to its global coverage capability, SkyBridge will enable service providers to offercontinuous, highly interactive broadband services to subscribers worldwide, regardless oftheir location or the nature of their local communications infrastructure.

Each satellite illuminates an area of 3,000 km in radius, with a maximum of 45 spotbeams:each spotbeam corresponds to the coverage area of one gateway (350 km in radius).

5 Space Systems Loral proposes a satellite system called CyberStar which consists of 3 GEO satellites.Loral requests use of spectrum in the 28.35-28.6 and 29.5-30.0 GHz bands for service uplink operations and the band18.95-19.2 and 19.7-20.2 GHz for its service downlink operations. Loral requests authority for inter-satellite links in the 60GHz band.Each satellite in the CyberStar system will have on-board processing and switching capabilities to promote maximumcommunication flexibility. Each satellite will provide antenna coverage with twenty-seven regional beams. Loral proposes touse Frequency Division Multiple (FDM) / Time Division Multiplexed (TDM) protocol for uplink and TDM for downlink.The CyberStar network will provide services such as video telephony and videoconferencing, high-speed data networks and"bandwidth on demand".


- 19 -

The decentralized architecture makes it easy to adapt services to local requirements andpreferences via local ground stations (gateways). Since all the processing is on the ground,the satellite link is a simple so-called “bent” function (no on-board processing, no inter-satellite links).

The gateway consists of a switching and routing subsystem, providing interfaces with localservers and with terrestrial IP networks such as Internet, broadband and narrowband switchednetworks, and leased lines through an Asynchronous transfer mode (Atm) broadband switch.Each gateway controls and manages all SkyBridge traffic within its respective coverage area.

SkyBridge will operate just as fast as existing, terrestrial broadband networks thanks to theshort, round-trip propagation times (20 milliseconds) of low Earth orbit satellites. There is alsono need to adapt existing applications or protocols.

The link between end-users and the system is asymmetrical, with data rates of up to 60 Mbpsto the user and up to 2 Mbps on the return link. The asymmetrical design is optimized forInternet-type communications, characterized by random bursts of asymmetrical datatransmission. Increments in data rates are in 16 kbps steps, thereby providing the user with"bandwidth on demand."

The SkyBridge system will optimize the use of the frequency spectrum by operating in theKu-band, while fully protecting existing geostationary and terrestrial users of that bandthrough an innovative concept of frequency re-use.SkyBridge requests to use a total of 1.05 GHz of spectrum within the 12.75-13.25 GHz,13.75-14.5 GHz, and 17.3-17.8 GHz frequency bands for Earth-to-space transmissions. Itproposes to use discrete frequency bands within these band segments for transmissions fromgateway stations and from ubiquitous user terminals. SkyBridge also requests to use a totalof 1.05 GHz within 10.75-12.75 GHz for space-to-Earth transmissions.

SkyBridge will deliver various interactive broadband services to business and consumersubscribers, such as :− High-speed access to Internet and on-line services,− Access to corporate networks for tele-commuting/tele-work, LAN interconnections, Wide

Area networks,− Tele-education and tele-training,− Tele-medecine− Entertainment and cultural services such as video on demand.

In addition, other services will be added according to demand, such as enhanced narrowbandservices (voice, basic video conferencing, data).Telecommunications needs vary widely from one area to another.


It has not been possible to establish a contact with Skybridge, and to know whetheraeronautical services are envisaged.


- 20 -

5. Summary

The following table gives an overview of the different satellite systems presented in thisreport. The information contained in this table comes from satellite providers, or web-siteswhen no contact was possible. These data can be improved as far as most systems are atpresent in a phase of development.

Com

mun

icat

ions

Cos

t

$0.3

per

kbp

s

not c

omm

erci

al

$3 p

er m

inut

e

$0.3

5-0.

55/m

in

$1-$

2 pe

r m

inut

e

not c

omm

erci

al

"fib

er-li

ke"

Ava

ibili

ty

%

99.9

985

> 9

9.9

> 9

9.9

Ban

dwid

th

on-d

eman

d

futu

re o

ptio

n

no in

fo

16k-

2Mbp

s

64k-

155M

bps

16k-

60M

bps

Aer

onau

tical

band

wid

th

0.6-

10.5

kbps

2.4k

bps

64kb

ps m

axi

2.4

kbps

no in

fo

4.8-

38.4

kbps

9.6k

bps

pack

et m

ode

up to

64k

bps

no in

fo

Air-

to-A

ir

sat c

omm

s

no no

plan

ed

for

2003

no in

fo

no in

fo

no no no

no in

fo

Ser

vice

AP

C

com

plia

nce

yes/

ICA

O

no

yes/

?

no in

fo

yes/

not

ICA

O

plan

ed

yes/

not

ICA

O

no

no in

fo

Ser

vice

AT

S

com

plia

nce

yes/

ICA

O

only

/not

fully

ICA

O

yes/

ICA

O

no in

fo

plan

ed/IC

AO

(Inm

arsa

t)

yes/

ICA

O

no no

no in

fo

Sub

crib

er

serv

ices

digi

tal v

oice

circ

uit/p

acke

t mod

e da

ta

circ

uit/p

acke

t

mod

e da

ta

voic

e, d

ata,

fax,

pag

ing

circ

uit/p

acke

t mod

e da

ta

voic

e, d

ata,

fax,

pag

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- 21 -

6. Conclusion

The present study shows that most of the new satellite providers are currently involved in thedevelopment of passenger rather than Air Traffic Services applications. Two main reasonscan explain this choice; firstly, the commercial services for aircraft passengers are morebandwidth-consuming/profitable for the provider than the low-bandwidth ATS applications;secondly, a satellite provider who wants to offer ATS services will have to assume the extra-cost and constraint to be ICAO compliant for a very limited market (low overall throughputwith a maximum of 50 bps per aircraft); the APC applications do not require to be ICAOcompliant.

Today, the aeronautical/ATS services are only available on dedicated satellite systems likeInmarsat. The latter proposes a full range of aeronautical services (voice and data) for flight-crew, cabin-staff and passengers, world-wide. Experiments have been performed through theADS-Europe trials. Having demonstrated the poor performance (protocol overhead), lowreliability and high cost ($0.3 per kbps) of this first generation of Aeronautical Mobile SatelliteSystem (AMSS), it has been restricted to operation in oceanic airspace with low air trafficdensity. This outcome is the consequence of an early standardization which occurred beforethe experimentation and evaluation phases.

The European Space Agency has commissioned a study to overcome the weaknesses of theformer system. This study aims to investigate the feasibility of a low-cost aeronauticalSatellite Data-Link System to provide for the needs of Air Traffic Services over continentalareas with high air traffic density. The first objective of the ATS-dedicated SDLS will be tooptimize ADS (Automatic Dependent Surveillance). The SDLS will have to offer a quality ofservice for dependability and transmission delays required for high air-traffic areas.

In 1995, the Japanese Ministry of Transportation placed a contract for a Multi-functionTransport Satellite. The MTSAT is the first GEO satellite system to have full Air TrafficControl capabilities with communication transmission channels as well as enhanced GlobalPositioning System signal transmission channels. Its objectives are to optimize the region’sair traffic routes and to enable aircraft to take off and land automatically. The system will beoperational throughout the Asia-Pacific region in 1999. At present, the MTSAT information ispoor. Nevertheless, it will be interesting in future to go on with investigations on the systemdesign features, and to follow its experiments.

Except for these 2 projects and the SDLS study (which are ICAO compliant), there is no realengagement of the satellite providers for the ATS applications. Today for example, noexisting system proposes and foresees a direct Air-to-Air dialogue via satellite. This is due tothe communication process which must necessarily pass through the Telecom providergateways (lobby). The other significant point is that the satellites incorporate only a repeaterfunction without any on-board demodulation or processing. The Air-to-Air aspect isnevertheless essential for the implementation of the Free-Flight concept (cf Freer project[Ref. 3,4]), so as to exchange position report and flight profile data directly between aircraft.

The other satellite systems including new proposals give priority to high-bandwidthcommercial services for return-on-investment reasons. Their aeronautical segment isprimarily focused on providing communications and information services to commercial andcorporate passengers. The providers have well understood the opportunity of this market. Inthe future, data bearer services supporting fax, email and file transfer will becomeincreasingly important to the business user.

It was not easy to establish contacts with satellite providers to get general information abouttheir product. Most of these contacts were even interrupted as soon as the requestsconcerned specific points which needed more detailed information.

It is important to know that numerous satellite systems are currently in a phase ofdevelopment which means that people are very busy and do not really have the time toengage in technical dialogue with potential users such as Eurocontrol (bluff or reality ???).


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The competition side is also very important in this branch of industry : there are manycompetitors and a considerable potential/market. Consequently, the competitors want to keepa certain confidentiality so as not to divulge the strategic orientations and options of thesystems under development.

Return on investment should be done on the APC part that will be necessarily not ICAOcompliant for performance, technology and cost-effectiveness reasons. As a result, there willbe a divergence of technology between the ATS and APC applications.

On the assumption that the ICAO standards do not progress, the CNS/ATM domain couldundoubtedly not benefit from technological advancement, better performances and low-cost.

With regard to the ICAO standard, the LEO technology can not provide moreadvantage or improvement than the GEO systems.

With the new ICAO compliant constellations (Iridium, ICO, MTSAT), one cannot expectbetter performances in the ATS implementation insofar as experiments are going to beperformed in the beginning of 1998 (Iridium). In conclusion, these satellite systems will notoffer more than Inmarsat. The Inmarsat Aero services have still a nice future...Nevertheless, it is urgent to design the ATN for High Density areas (ATN-HD concept).

The Telecom providers who work on new constellations, do not consider theTeledesic project as viable. Unlike the other Telecom-oriented systems, it intr oduces aTelecom-Network approach with its Inter-Satellite Links and on-board pro cess ing.

All new satellite telecom systems are frozen. Rather than define another Aero system withnew specifications, it will be more efficient to perform an evaluation and qualification phase ofthe current and under-development systems so as to retain at least two competing systems(e.g. Teledesic...). This evaluation phase will have to determine - if a ICAO qualification ofone of the selected systems is possible or not - the points or specifications which have to bemodified in the SARPs. This process is quite expensive but cheaper than to define a newspecific system.

Anyway, a correct methodology would consist in performing, after initial experiments, anevaluation phase of the system, and only then, a possible ICAO qualification might bedetermined.

The aeronautical domain can get benefits from COTS6 technologies insofar as the newsystems under-development take into account the aeronautical constraints.

The CNS/ATM satellite approach s eems to be in a dead end concer ning the use of thenew constellations. It is now mandatory to perform another satellite study includingall the new aspects required for ATS (Inter-Satellite Links, on-board pro cess ing, Air-to-Air dialogue, emergent Telecom-Network tec hnologies...).

6 For its part, the NASA has not hesitated to use COTS technologies for its Mars Pathfinder mission. Several modules of thespace probe such as the monitoring-cameras are based on-COTS products for economical reasons. Today, everybodyknows that the mission is a total success.


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Appendix 1: Definitions

⇒ ⇒ Asynchronous transfer mode (Atm)

Atm is an international ISDN high-speed, high-volume, packet-switching transmissionprotocol standard (Broadband-ISDN). Atm uses short, uniform, 53-byte cells to divide datainto efficient, manageable packets for ultra-fast switching through a high performancecommunications network. The 53-byte cells contain 5-byte destination address headers and48 data bytes. The header is organized for efficient switching in high-speed hardwareimplementations and carries payload-type information, virtual-circuit identifiers, and headererror check. Atm is the first packet-switched technology designed to support integrated voice,video and data communications applications. The fixed cell size ensures that time-criticalinformation such as voice or video is not adversely affected by long data frames or packets.Atm offers the integration of the Local Area Networks (LAN) and the Wide Area Networks(WAN). It currently accommodates transmission speeds from 64 Kbps to 622 Mbps, and willsupport gigabit speeds in the future.

Atm is connection oriented. Organizing different streams of traffic in separate calls allows theuser to specify the resources required (Quality of Service) and allows the network to allocateresources based on these needs. Multiplexing multiple streams of traffic on each physicalfacility (between the end user and the network or between network switches) combined withthe ability to send the streams to many different destinations, enables cost savings through areduction in the number of interfaces and facilities required to construct a network.

Atm standards defined two types of Atm connections : virtual path connections (VPC) whichcontain virtual channel connections (VCC).A virtual channel connection (or virtual circuit) is the basic unit, which carries a single streamof cells, in order, from user to user.A collection of virtual circuits can be bundled together into a virtual path connection. A virtualpath connection can be created from end-to-end across an Atm network. In this case, theAtm network does not route cells belonging to a particular virtual circuit. All cells belonging toa particular virtual path are routed the same way through the Atm network, thus resulting infaster recovery in case of major failures.

The benefits of Atm are the following :

• High performance via hardware switching,• Dynamic bandwidth for bursty traffic,• Class-of-service support for multimedia (Constant bit rate for telephone, videoconference

and television - Variable bit rate-non real time for multimedia, e-mail - Variable bit rate-real time for interactive compressed video - Available bit rate for file transfer and e-mail -Unspecified bit rate for TCP/IP),

• Scaleability in speed and network size,• Common LAN/WAN architecture,• Opportunities for simplification via VC architecture,• International standards compliance.

There are two bodies that are promoting Atm standardization: the Internet Engineering TaskForce (IETF) and the Atm Forum. The IETF is the primary "group" responsible for thedevelopment of the specifications which are passed to the Internet Engineering SteeringGroup for standardization. The Atm Forum is a consortium of computer andtelecommunications users and vendors that develop and promote specifications. Thesespecifications are presented to the International Telecommunications Union (ITU) forstandardization.


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⇒ ⇒ Internet Protocol next generation (IPng/IPv6) overview

The current Internet Protocol (named IPv4) focus is to connect computers together in thelarge business, government and education markets. In the last few years, these marketshave been growing at an exponential rate which caused the need for a next generation IP.The main drawbacks of the IP addresses version 4 are related to the limited amount ofnetworks or host numbers, to the rigidity of an address divided in only two parts and to themissing and interesting functions.

IPv6/IPng is a new version of Internet Protocol (IP) which is designed to be an evolutionaystep from IPv4. There are a number of reasons why IPv6/IPng is appropriate for the nextgeneration of the Internet Protocol. It solves the Internet scaling problem, provides a flexibletransition mechanism for the current Internet, and was designed to meet the needs of newmarkets such as nomadic personal computing devices, networked entertainment, and devicecontrol. It does this in a evolutionary way which reduces the risk of architectural problems.

The changes from IPv4 to IPv6/IPng fall in the following categories :

• Expanded routing and addressing capabilitiesIPng increases the IP address size from 32 bits to 128, to support more levels ofaddressing hierarchy and much greater number of addressables nodes, and simplerauto-configuration of addresses. The scalability of multicast routing is improved byadding a “scope” field to multicast addresses.

• A new type of address called a “anycast address” is defined, to identify sets of nodeswhere a packet sent to an anycast address is delivered to one of the nodes. The use ofanycast addresses in the IPng source route allows nodes to control the path which theirtraffic flows.

• Header format simplification

Some IPv4 header fields have been dropped or made optional, to reduce the common-case processing cost of packet handling and to keep the bandwidth cost of IPng headeras low as possible despite the increased size of the addresses. Even though the IPngaddresses are four time longer than the IPv4 addresses, the IPng header is only twicethe size of IPv4 header.

• Improved support for optionsChanges in the way IP header options are encoded allows for more efficient forwarding,less stringent limits on the length of options, and greater flexibility for introducing newoptions in the future.

• Quality-of-Service capabilitiesA new capability is added to enable the labeling of packets belonging to particular traffic“flows” for which the sender requests special handling, such as non-default quality ofservice or “real-time” service.

• Authentication and privacy capabilitiesIPng includes the definition of extensions which provide support for authentication, dataintegrity, and confidentiality. This is included as a basic element of IPng and will beincluded in all implementations.

In summary, IPv6/IPng is a new version of IP. It can be installed as a normal softwareupgrade in internet devices. It is interoperable with the current IPv4. Its deployment strategywas designed to have no any “flag” days. IPv6/IPng is designed to run well on highperformance networks (e.g. Atm) and at the same time is still efficient for low bandwidthnetworks (e.g. wireless).


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⇒ ⇒ Asynchronous Time Division Multiple Access (A T D M A)

Asynchronous TDMA (cf. TDMA).

⇒ ⇒ Code Division Multiple Access (C D M A)

CDMA uses "pseudo-random code sequences"; they are used by both the mobile station andthe base station to distinguish between conversations. CDMA uses these code sequences asa means of distinguishing between individual conversations. All users in the CDMA systemuse the same carrier frequency and may transmit simultaneously. CDMA is a drivingtechnology behind the rapidly advancing personal communications industry. Because of itsgreater bandwidth, efficiency, and multiple access capabilities, CDMA is becoming a leadingtechnology for relieving the spectrum congestion caused by the explosion in popularity ofcellular mobile phones, fixed wireless telephones, and wireless data terminals. Sincebecoming an officially recognized digital cellular protocol, CDMA is being rapidlyimplemented in the wireless communications networks of many large communicationscorporations.

⇒ ⇒ Frequency Division Multiple Access (F D M A)

FDMA divides radio channels into a range of radio frequencies and is used in the traditionalanalog cellular system. With FDMA, only one subscriber is assigned to a channel at a time.

It is the oldest and still one of the most common method for channel allocation. In thisscheme, the available satellite channel bandwidth is broken into frequency bands for differentearth stations. This means that guard bands are needed to provide separation between thebands. Also the earth stations must be carefully power controlled to prevent the microwavepower spilling into the bands for the other channels.

⇒ ⇒ Time Division Multiplexing (T D M)

Technique in which information from multiple channels can be allocated bandwidth on atransmission system based on time.

⇒ ⇒ Time Division Multiple Access (T D M A)

A shared channel access mechanism based on time division multiplexing. TDMA dividesconventional radio channels into time slots to obtain higher capacity Global System for GSM(Mobile Communications). No other conversations can access an occupied TDMA channeluntil the channel is vacated.


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Appendix 2: Contacts

Contact Name Contacts Phone numbersL. Crouzard [email protected] 01 69 88 73 43G. Gawinowski [email protected] 01 69 88 74 46C. Musson [email protected] 01 69 88 74 51ISA [email protected]

Documents

EUROCONTROL EXPERIMENTAL CENTRE · EUROCONTROL Experimental Centre B.P.15 F ... AIRCOM Airborne Communications. Ipv6 ... GSM Global System for Mobile communications