SATELLITE COMMUNICATIONS SYSTEMS

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SATELLITE COMMUNICATIONS

SYSTEMS Fifth Edition

SATELLITE COMMUNICATIONS

SYSTEMS Systems, Techniques and Technology

Fifth Edition

Gerard Maral Ecole Nationale Superieure des Telecommunications,

Site de Toulouse, France

Michel Bousquet Ecole Nationale Superieure de l’Aeronautique et de l’Espace (SUPAERO),

Toulouse, France

Revisions to fifth edition by Zhili Sun University of Surrey, UK with contributions from Isabelle Buret,

Thales Alenia Space

This edition first published 2009

Ó 2009 John Wiley & Sons Ltd.

Registered office

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Library of Congress Cataloging-in-Publication Data

Maral, Gerard.

[Systemes de telecommunications par satellites English]

Satellite communications systems / Gerard Maral, Michel Bousquet — 5th ed.

Typeset in 9/11 pt Palatino by Thomson Digital, Noida, India.

Printed in Singapore by Markono Print Media Pte Ltd.

This book is printed on acid-free paper responsibly manufactured from sustainable forestry,

in which at least two trees are planted for each one used for paper production.

Original translation into English by J.C.C Nelson.

2.3 Perturbations of orbits 68

4.5 Coded modulation 140

5.7.4 Link performance under rain conditions 209

5.11 Link performance with multibeam antenna coverage vs monobeam

6.6 Time division multiple access (TDMA) 260

7.7 Broadband satellite networks 322

8.7 Monitoring and control; auxiliary equipment 432

11.2.3 Commonwealth of Independent States (CIS) 636

13.3.2 Elements in parallel (static redundancy) 685

Reproduction of figures extracted from the 1990 Edition of CCIR Volumes (XVIIthPlenary Assembly, D€usseldorf, 1990), the Handbook on Satellite Communications (ITUGeneva, 1988) and the ITU-R Recommendations is made with the authorisation of theInternational Telecommunication Union (ITU) as copyright holder

The choice of the excerpts reproduced remains the sole responsibility of the authorsand does not involve in any way the ITU

The complete ITU documentation can be obtained from:

International Telecommunication Union General Secretariat, Sales Section Place des Nations, 1211 GENEVA 20, Switzerland Tel: +41 22 730 51 11 Tg: Burinterna Geneva Telefax: + 41 22 730 51 94 Tlx: 421 000 uit ch

A/D Analog-to-Digital conversion

ABCS Advanced Business Communications

via Satellite

ACI Adjacent Channel Interference

Technology Satellite

ADC Analog to Digital Converter

ADM Adaptive Delta Modulation

ADPCM Adaptive Pulse Code Modulation

ADSL Asymmetric Digital Subscriber Line

AES Audio Engineering Society

ALG Application Level Gateway

AMAP Adaptive Mobile Access Protocol

AMPS Advanced Mobile Phone Service

AMSC American Mobile Satellite Corp.

AMSS Aeronautical Mobile Satellite Service

ANSI American National Standards

Institute

AOCS Attitude and Orbit Control System

AOM Administration, Operation and

Maintenance

APC Adaptive Predictive Coding

Interface

ARQ-GB(N) Automatic repeat ReQuest-Go Back N

ARQ-SR Automatic repeat ReQuest-Selective

Repeat

ARCS Astra Return Channel System

ARQ-SW Automatic repeat ReQuest-Stop and

Wait

ARTES Advanced Research in

TElecommunications Systems (ESA programme)

ASCII American Standard Code for

Information Interchange ASIC Application Specific Integrated

Circuit

Number ASN Abstract Syntax Notation

Telecommunications Equipment (ESA programme)

ASTP Advanced Systems and Technology

Programme (ESA programme) ASYNC ASYNChronous data transfer

BAPTA Bearing and Power Transfer

Assembly

BCR Battery Charge Regulator BDR Battery Discharge Regulator BECN Backward explicit congestion

notification BEP Bit Error Probability

BFSK Binary Frequency Shift Keying BGMP Border Gateway Multicast

Protocol

BHCA Busy Hour Call Attempts

BIS Broadband Interactive System BITE Built-In Test Equipment

BPSK Binary Phase Shift Keying

BSC Binary Synchronous

Communications (bisync)

BSS Broadcasting Satellite Service

BTS Base Transceiver Station

CBDS Connectionless broadband data

service

CBO Continuous Bit Oriented

CCI CoChannel Interference

CCIR Comite Consultatif International

des Radiocommunications

(International Radio Consultative

Committee)

CCITT Comite Consultatif International du

Telegraphe et du Telephone (The

International Telegraph and

Telephone Consultative Committee)

CCSDS Consultative Committee for Space

Data Systems

CDMA Code Division Multiple Access

CEC Commission of the European

Communities

CELP Code Excited Linear Prediction

CENELEC Comite Europeen pour la

Assignment Multiple Access

CFRA Combined Fixed/Reservation

Assignment

CIR Committed Information Rate

CIRF Co-channel Interference Reduction

Factor

States

CLDLS ConnectionLess Data Link Service

CLEC Competitive Local Exchange

Carrier

CLNP ConnectionLess Network Protocol

CLTU Command Link Transmission Unit

CMOS Complementary Metal Oxide

Semiconductor

CNES Centre National d’Etudes Spatiales

(French Space Agency) CODLS Connection Oriented Data Link

Service COMETS Communications and Broadcasting

Engineering Test Satellite

COST European COoperation in the field of

Scientific and Technical research COTS Commercial Off The Shelf CPS Chemical Propulsion System CRC Communications Research Centre

(Canada)

CSMA Carrier Sense Multiple Access

D-AMPS Digital Advanced Mobile Phone

System D-M-PSK Differential M-ary Phase Shift Keying

DAB Digital Audio Broadcasting DAC Digital to Analog Converter DAMA Demand Assignment Multiple Access DARPA Defense Advanced Research Project DASS Demand Assignment Signalling and

Switching

dBm Unit for expression of power level in

dB with reference to 1 mW dBm Unit for expression of power level in

dB with reference to 1 mW dBmO Unit for expression of power level in

dBm at a point of zero relative level (a point of a telephone channel where the 800 Hz test signal has a power of

1 mW)

DBFN Digital Beam Forming Network DBS Direct Broadcasting Satellite

DCCH Dedicated Control Channel DCE Data Circuit Terminating Equipment DCFL Direct Coupled Fet Logic

DCME Digital Circuit Multiplication

Equipment DCS Digital Cellular System (GSM At 1800

MHz) DCT Discrete Cosine Transform DCU Distribution Control Unit DDCMP Digital Data Communications

Message Protocol (a DEC Protocol)

DE-M-PSK Differentially Encoded M-ary

Phase Shift Keying

DECT Digital European Cordless

DQDB Distributed Queue Dual Bus

DSCP Differentiated Service Code Point

DSI Digital Speech Interpolation

DSL Digital Subscriber Loop

DSP Digital Signal Processing

DTE Data Terminating Equipment

DTTL Data Transition Tracking Loop

DVB Digital Video Broadcasting

DWDM Dense Wave Division Multiplexing

EBU European Broadcasting Union

EIA Electronic Industries Association

EIR Equipment Identity Register

EIRP Effective Isotropic Radiated

Power (W)

ELSR Edge Label Switch Router

EMC ElectroMagnetic Compatiblity

EMF ElectroMagnetic Field

EMI ElectroMagnetic Interference

EMS European Mobile Satellite

EPC Electric Power Conditioner

EPIRB Emergency Position Indicating Radio

Beam

Committee

Office (of the ERC)

ESTEC European Space Research and

Technology Centre

Standard, created within ETSI

ETSI European Telecommunications

FDDI Fibre Distributed Data Interface FDM Frequency Division Multiplex FDMA Frequency Division Multiple Access FEC Forward Error Correction

FES Fixed Earth Station FET Field Effect Transistor FETA Field Effect Transistor Amplifier FFT Fast Fourier Transform

FIFO First In First Out

FMS Fleet Management Service FMT Fade Mitigation Technique FODA FIFO Ordered Demand Assignment FPGA Field Programmable Gate Array FPLMTS Future Public Land Mobile

Equipment GCS Ground Control Station

GEO Geostationary Earth Orbit GMDSS Global Maritime Distress and Safety

System

GPRS General Packet Radio Service GPS Global Positioning System GRE Generic Routing Encapsulation GSM Global System for Mobile

communications GSO Geostationary Satellite Orbit GTO Geostationary Transfer Orbit HDB3 High Density Binary 3 code HDLC High Level Data Link Control HDTV High Definition TeleVision HEMT High Electron Mobility Transistor HEO Highly Elliptical Orbit

HIO Highly Inclined Orbit

HIPERLAN HIgh PErformance Radio Local Area

Network

HPT Hand Held Personal Telephone

HTTP Hyper Text Transfer Protocol

IAU International Astronomical Unit

IBA Independent Broadcasting Authority

IBS International Business Service

ICMP Internet Control Message Protocol

ICI Interface Control Information

ICO Intermediate Circular Orbit

IGMP Internet Group Management Protocol

IDC Intermediate rate Digital Carrier

IDR Intermediate Data Rate

IDU Interface Data Unit, also InDoor Unit

IEEE Institute of Electrical and Electronic

Engineers

IETF Internet Engineering Task Force

IFRB International Frequency Registration

Board

IGMP Internet Group Management Protocol

ILS International Launch Services

IMP Interface Message Processor

IMSI International Mobile Subscriber

IP Internet Protocol (a network layer

datagram protocol)

IPA Intermediate Power Amplifier

IPE Initial Pointing Error

IPsec IP security policy

IRCD Internet Relay Chat Program Server

(a teleconferencing application)

IRD Internet Resources Database

IRD Integrated Receiver Decoder

ISDN Integrated Services Digital Network

ISC International Switching Center

ISL Intersatellite Link

ISO International Organisation for

Standardisation ISS Inter-Satellite Service ISU Iridium Subscriber Unit ITU International Telecommunication

Union

IVOD Interactive Video On Demand

JDBC Java Database Connectivity JPEG Joint Photographic Expert Group

LAPB Link Access Protocol Balanced LDP Label Distribution Protocol

LFSR Linear Feedback Shift Register LHCP Left Hand Circular Polarization

LMDS Local Multipoint Distribution System LMSS Land Mobile Satellite Service

LPC Linear Predictive Coding

LSR Label Switching Router

M-PSK M-ary Phase Shift Keying

(also Monitoring, Alarm and Control) MACSAT Multiple Access Satellite

MAMA Multiple ALOHA Multiple Access

MCPC Multiple Channels Per Carrier MEB Megabit Erlang Bit rate MEO Medium altitude Earth Orbit

MESFET Metal Semiconductor Field Effect

Transistor

MIC Microwave Integrated Circuit MIDI Musical Instrument Digital Interface MIFR Master International Frequency

Register MMDS Multipoint Multichannel Distribution

System

MMIC Monolithic Microwave Integrated

Circuit

MPEG Motion Picture Expert Group

MPLS Multi-Protocol Label Switching

MPSK M-ary Phase Shift Keying

MSC Mobile Switching Center

MSS Mobile Satellite Service

MTBF Mean Time Between Failure

NASDA National Aeronautics And Space

Development Agency (Japan)

NAT Network Address Translation

NGSO Non-Geostationary Satellite Orbit

NIS Network Information System

NNTP Network News Transfer Protocol

NOAA National Oceanic and Atmospheric

Administration

NORM Nack-Oriented Reliable Multicast

NSO National Standardisation

Organisation

OACSU Off-Air Call Set-Up

OICETS Optical Inter-orbit Communications

Engineering Test Satellite

OSI Open System Interconnection

OSPF Open Shortest Path First

PABX Private Automatic Branch eXchange

PACS Personal Access Communications

System

PAD Packet Assembler/Disassembler

PBX Private (automatic) Branch eXchange

PCCH Physical Control CHannel

PCN Personal Communications Network

(often refers to DCS 1800) PCS Personal Communications System PDCH Physical Data CHannel

PDF Probability Density Function PDH Plesiochronous Digital Hierarchy

PHEMT Pseudomorphic High Electron

Mobility Transistor

PILC Performance Implication of Link

Characteristics PIMP Passive InterModulation Product

PLMN Public Land Mobile Network

PSPDN Packet Switched Public Data Network PSTN Public Switched Telephone Network

PTN Public Telecommunications Network PTO Public Telecommunications Operator PVA Perigee Velocity Augmentation PVC Permanent Virtual Circuit

QPSK Quaternary Phase Shift Keying RAAN Right Ascension of the Ascending

Node RACE Research and development in

Advanced Communications

RADIUS Remote Authentication Dial In User

Service

RAN Radio Area Network

RARC Regional Administrative Radio

Conference

RDSS Radio Determination Satellite Service

ETSI Technical Committee

RFHMA Random Frequency Hopping

Multiple Access

RFI Radio Frequency Interference

RHCP Right-Hand Circular Polarization

RIP Routing Information Protocol

RLAN Radio Local Area Network

RLL Radio in the Local Loop

RLOGIN Remote login application

RMTP Realisable Multicast Transport

Protocol

RNCC Regional Network Control Center

RORA Region Oriented Resource Allocation

RSVP Resource reSerVation Protocol

RTCP Real Time transport Control Protocol

RTP Real Time transport Protocol

S-ALOHA Slotted ALOHA protocol

SAMA Spread ALOHA Multiple Access

SCP Service Control Point

SCPC Single Channel Per Carrier

SDH Synchronous Digital Hierarchy

SDLC Synchronous Data Link Control

SEP Symbol Error Probability

SHF Super High Frequency (3 GHz to

30 GHz) SIM Subscriber Identity Module S-ISUP Satellite ISDN User Part SIT Satellite Interactive Terminal SKW Satellite-Keeping Window

SLIC Subscriber Line Interface Card SMATV Satellite based Master Antenna for TV

distribution SME Small and Medium Enterprise SMS Satellite Multi-Services SMTP Simple Mail Transfer Protocol SNA Systems Network Architecture (IBM) SNDCP SubNet Dependent Convergence

Protocol SNEK Satellite NEtworK node computer SNG Satellite News Gathering

Protocol SNR Signal-to-Noise Ratio

SOHO Small Office Home Office SORA Satellite Oriented Resource

Allocation SORF Start of Receive Frame SOTF Start of Transmit Frame SPADE Single-channel-per-carrier PCM

multiple Access Demand assignment Equipment

S-PCN Satellite Personal Communications

Network S/PDIF Sony/Philips Digital Interface

Format SPDT Single-Pole Double-Throw (switch) SPMT Single-Pole Multiple-Throw (switch) SPT Stationary Plasma Thruster SPU Satellite Position Uncertainty

SSMA Spread Spectrum Multiple Access

SSOG Satellite Systems Operations Guide

(INTELSAT) SSP Signalling Switching Point SSPA Solid State Power Amplifier SS-TDMA Satellite Switched TDMA STC ETSI Sub-Technical Committee STM Synchronous Transport Module STS Space Transportation System

SVC Switched Virtual Circuit

SW Stop and Wait

TACS Total Access Communication System

TCP Transmission Control Protocol

TDM Time Division Multiplex

TDMA Time Division Multiple Access

TDRS Tracking and Data Relay Satellite

TELNET remote terminal application

TEM Transverse ElectroMagnetic

TETRA Trans European Trunk Radio

TFTS Terrestrial Flight Telephone System

TIA Telecommunications Industry

TTC Telemetry, Tracking and Command

TTCM Telemetry, Tracking, Command and

UDLR UniDirectional Link Routing

UHF Ultra High Frequency (300 MHz to

3 GHz)

Telecommunications System UPS Uninterruptible Power Supply

Telecommunications USAT Ultra Small Aperture Terminal

VC Virtual Channel (or Container) VCI Virtual Channel Identifier VDSL Very high-speed Digital

Subscriber Line VHDL VHSIC Hardware Description

Language VHSIC Very High Speed Integrated

Circuit VHF Very High Frequency (30 MHz to

300 MHz) VLR Visitor Location Register VLSI Very Large Scale Integration

VPA Variable Power Attenuator VPC Virtual Path Connection VPD Variable Phase Divider VPS Variable Phase Shifter VPI Virtual Path Identifier VPN Virtual Private Network

Terminal VSELP Vector Sum Excitation Linear

Prediction VSWR Voltage Standing Wave Ratio

WAP Wireless Application Protocol WARC World Administrative Radio

Conference

Discrimination XPI Cross Polarisation Isolation Xponder Transponder

a orbit semi-major axis

A azimuth angle (also attenuation, area,

availability, traffic density and carrier

amplitude)

A eff effective aperture area of an antenna

A AG attenuation by atmospheric gases

A RAIN attenuation due to precipitation and

clouds

A P attenuation of radiowave by rain for

percentage p of an average year

b voice channel bandwidth (3100 Hz from

300 to 3400 Hz)

B n noise measurement bandwidth at

baseband (receiver output)

B N equivalent noise bandwidth of

ðC=N 0 Þ U uplink carrier power-to-noise power

spectral density ratio

ðC=N 0 Þ D downlink carrier power-to-noise power

spectral density ratio

ðC=N 0 Þ IM carrier power-to-intermodulation noise

power spectral density ratio

ðC=N 0 Þ I carrier power-to-interference noise

power spectral density ratio

ðC=N 0 ÞI;U uplink carrier power-to-interference

noise power spectral density ratio

ðC=N 0 ÞI;D downlink carrier power-to-interference

noise power spectral density ratio

ðC=N 0 Þ T carrier power-to-noise power spectral

density ratio for total link

D diameter of a reflector antenna (also used

as a subscript for ‘downlink’)

e orbit eccentricity

E elevation angle (also energy and electric

field strength)

E b energy per information bit

E c energy per channel bit

F c nominal carrier frequency

f d antenna focal length

f m frequency of a modulating sine wave

f max maximum frequency of the modulating

baseband signal spectrum

G power gain (also gravitational constant)

G sat gain at saturation

G R receiving antenna gain in direction of

transmitter

G T transmitting antenna gain in direction of

receiver

G Rmax maximum receiving antenna gain

G Tmax maximum transmitting antenna gain

G SR satellite repeater gain

G/T gain to system noise temperature ratio of

a receiving equipment

G CA channel amplifier

G FE front end gain from satellite receiver

input to satellite channel amplifier input

G ss small signal power gain

i inclination of the orbital plane

K P AM/PM conversion coefficient

K T AM/PM transfer coefficient

l earth station latitude

L earth station-to-satellite relative

longitude also loss in link budget

calculations, and loading factor of FDM/

FM multiplex also message length (bits)

L e effective path length of radiowave

through rain (km)

L FRX receiver feeder loss

L FTX transmitter feeder loss

L FS free space loss

L POL antenna polarisation mismatch loss

L R receiving antenna depointing loss

LT transmitting antenna depointing loss

mc power reduction associated with

multicarrier operation

M mass of the earth (kg) (also number of

possible states of a digital signal)

N 0 noise power spectral density (W/Hz)

ðN 0 Þ U uplink noise power spectral density

p w rainfall worst month time percentage

P power (also number of bursts in a TDMA

frame)

P b information bit error rate

P c channel bit error rate

P HPA rated power of high power amplifier (W)

P T power fed to the antenna (W)

P Tx transmitter power (W)

P R received power (W)

P Rx power at receiver input (W)

P is input power in a single carrier operation

(P o 1 ) sat saturation output power in a single

carrier operation mode

P i n input power in a multiple carrier

operation mode (n carriers)

P o n output power in a multiple carrier

operation mode (n carriers)

order X at output of a non-linear device

in a multicarrier operation mode (n carriers)

r distance between centre of mass (orbits)

R slant range from earth station to satellite

(km) (also symbol or bit rate)

R b information bit rate (s1)

R c channel bit rate (s1)

Rcall mean number of calls per unit time

R s symbol (or signalling) rate (s1)

S/N signal-to-noise power ratio at user’s end

T period of revolution (orbits) (s)

(also noise temperature (K))

T A antenna noise temperature (K)

T AMB ambient temperature (K)

T b information bit duration (s)

T B burst duration (s)

T c channel bit duration (s)

T e effective input noise temperature of a

four port element system (K)

T E mean sidereal day ¼ 86164:15

T eATT effective input noise temperature of an

U subscript for ‘uplink’

v true anomaly (orbits)

V satellite velocity (m/s)

V Lp/p peak-to-peak luminance voltage (V)

V Tp/p peak-to-peak total video signal voltage

(including synchronisation pulses)

V Nms root-mean-square noise voltage (V)

w psophometric weighting factor

X intermodulation product order (IMX)

a angle from boresight of antenna

G spectral efficiency (bit/s Hz)

d declination angle (also delay)

h antenna aperture efficiency

l wavelength (¼ c=f ) also longitude, also

message generation rate (s1)

u 3dB half power beamwidth of an antenna

wavelength ¼ c=f

u R receiving antenna pointing error

u T transmit antenna pointing error

F power flux density (w/m 2 )

F max max maximum power flux density at

transmit antenna boresight

F nom nom nominal power flux density

at receive end required to build up

a given power assuming maximum receive gain (no depointing)

F sat power flux density required to operate

receive amplifier at saturation

1 INTRODUCTION

This chapter describes the characteristics of satellite communication systems It aims to satisfythe curiosity of an impatient reader and facilitate a deeper understanding by directing him or her

to appropriate chapters without imposing the need to read the whole work from beginning to end

1.1 BIRTH OF SATELLITE COMMUNICATIONS

Satellite communications are the outcome of research in the area of communications and spacetechnologies whose objective is to achieve ever increasing ranges and capacities with the lowestpossible costs

The Second World War stimulated the expansion of two very distinct technologies—missilesand microwaves The expertise eventually gained in the combined use of these two techniquesopened up the era of satellite communications The service provided in this way usefullycomplements that previously provided exclusively by terrestrial networks using radio and cables.The space era started in 1957 with the launching of the first artificial satellite (Sputnik).Subsequent years have been marked by various experiments including the following: Christmasgreetings from President Eisenhower broadcast by SCORE (1958), the reflecting satellite ECHO(1960), store-and-forward transmission by the COURIER satellite (1960), powered relay satellites(TELSTAR and RELAY in 1962) and the first geostationary satellite SYNCOM (1963)

In 1965, the first commercial geostationary satellite INTELSAT I (or Early Bird) inauguratedthe long series of INTELSATs; in the same year, the first Soviet communications satellite of theMOLNYA series was launched

1.2 DEVELOPMENT OF SATELLITE COMMUNICATIONS

The first satellites provided a low capacity at a relatively high cost; for example, INTELSAT Iweighed 68 kg at launch for a capacity of 480 telephone channels and an annual cost of $32 500 perchannel at the time This cost resulted from a combination of the cost of the launcher, that of thesatellite, the short lifetime of the satellite (1.5 years) and its low capacity The reduction in cost isthe result of much effort which has led to the production of reliable launchers which can putheavier and heavier satellites into orbit (typically 5900 kg at launch in 1975, reaching 10 500 kg byAriane 5 ECA and 13 000 kg by Delta IV in 2008) In addition, increasing expertise in microwavetechniques has enabled realisation of contoured multibeam antennas whose beams adapt to theshape of continents, frequency re-use from one beam to the other and incorporation of higher

Ó 2009 John Wiley & Sons, Ltd.

power transmission amplifiers Increased satellite capacity has led to a reduced cost per telephonechannel.

In addition to the reduction in the cost of communication, the most outstanding feature is thevariety of services offered by satellite communications systems Originally these were designed

to carry communications from one point to another, as with cables, and the extended coverage ofthe satellite was used to set up long distance links; hence Early Bird enabled stations on oppositesides of the Atlantic Ocean to be connected However, as a consequence of the limited performance

of the satellite, it was necessary to use earth stations equipped with large antennas and therefore ofhigh cost (around $10 million for a station equipped with a 30m diameter antenna)

The increasing size and power of satellites has permitted a consequent reduction in the size ofearth stations, and hence their cost, leading to an increase in number In this way it has beenpossible to exploit another feature of the satellite which is its ability to collect or broadcast signalsfrom or to several locations Instead of transmitting signals from one point to another, transmissioncan be from a single transmitter to a large number of receivers distributed over a wide area or,conversely, transmission can be from a large number of stations to a single central station, oftencalled a hub In this way, multipoint data transmission networks and data collection networkshave been developed under the name of VSAT (very small aperture terminals) networks [MAR-95].Over 1 000 000 VSATs have been installed up to 2008 For TV services, satellites are of paramountimportance for satellite news gathering (SNG), for the exchange of programmes between broad-casters, for distributing programmes to terrestrial broadcasting stations and cable heads,

or directly to the individual consumer The latter are commonly called direct broadcasting bysatellite (DBS) systems, or direct-to-home (DTH) systems A rapidly growing service is digitalvideo broadcasting by satellite (DVB-S), developed in early 1991; the standard for the secondgeneration (DVB-S2) has been standardised by the European Telecommunication StandardInstitute (ETSI) These DBS systems operate with small earth stations having antennas with adiameter from 0.5 to 1 m

In the past, the customer stations were Receive Only (RCVO) stations With the introduction oftwo-way communications stations, satellites are a key component in providing interactive TVand broadband Internet services thanks to the implementation of the DVB satellite return channel(DVB-RCS) standard to the service provider’s facilities This uses TCP/IP to support Internet,multicast and web-page caching services over satellite with forward channel operating at severalMbit/s and enables satellites to provide broadband service applications for the end user, such asdirect access and distribution services IP-based triple-play services (telephony, Internet and TV)are more and more popular Satellites cannot compete with terrestrial Asymmetric DigitalSubscriber Line (ADSL) or cable to deliver these services in high-density population areas.However, they complement nicely the terrestrial networks around cities and in rural areas whenthe distance to the telephone router is too large to allow delivery of the several Mbit/s required torun the service

A further reduction in the size of the earth station antenna is exemplified in digital audiobroadcasting (DAB) systems, with antennas in the order of 10 cm The satellite transmits multi-plexed digital audio programmes and supplements traditional Internet services by offering one-way broadcast of web-style content to the receivers

Finally, satellites are effective in mobile communications Since the end of the 1970s, INMARSATsatellites have been providing distress signal services along with telephone and data commu-nications services to ships and planes and, more recently, communications to portable earthstations (Mini M or Satphone) Personal mobile communication using small handsets is availablefrom constellations of non-geostationary satellites (such as Iridium and Globalstar) and geosta-tionary satellites equipped with very large deployable antennas (typically 10 to 15 m) as with theTHURAYA, ACES, and INMARSAT 4 satellites The next step in bridging the gaps between fixed,mobile and broadcasting radiocommunications services concerns satellite multimedia broadcast

to fixed and mobile users Satellite digital mobile broadcasting (SDMB) is based on hybridintegrated satellite–terrestrial systems to serve small hand-held terminals with interactivity

1.3 CONFIGURATION OF A SATELLITE COMMUNICATIONS SYSTEMFigure 1.1 gives an overview of a satellite communication system and illustrates its interfacingwith terrestrial entities The satellite system is composed of a space segment, a control segment and

a ground segment:

— The space segment contains one or several active and spare satellites organised into a constellation

— The control segment consists of all ground facilities for the control and monitoring of the satellites,also named TTC (tracking, telemetry and command) stations, and for the management of thetraffic and the associated resources on-board the satellite

Figure 1.1 Satellite communications system, interfacing with terrestrial entities.

— The ground segment consists of all the traffic earth stations Depending on the type of serviceconsidered, these stations can be of different size, from a few centimetres to tens of metres.

Table 1.1 gives examples of traffic earth stations in connection with the types of service discussed

in Section 1.7 Earth stations come in three classes as illustrated in Figure 1.1: user stations, such ashandsets, portables, mobile stations and very small aperture terminals (VSATs), which allow thecustomer direct access to the space segment; interface stations, known as gateways, which inter-connect the space segment to a terrestrial network; and service stations, such as hub or feederstations, which collect or distribute information from and to user stations via the space segment.Communications between users are set up through user terminals which consist of equipmentsuch as telephone sets, fax machines and computers that are connected to the terrestrial network

or to the user stations (e.g a VSAT), or are part of the user station (e.g if the terminal is mobile).The path from a source user terminal to a destination user terminal is named a simplexconnection There are two basic schemes: single connection per carrier (SCPC), where the modulatedcarrier supports one connection only, and multiple connections per carrier (MCPC), where themodulated carrier supports several time or frequency multiplexed connections Interactivitybetween two users requires a duplex connection between their respective terminals, i.e twosimplex connections, each along one direction Each user terminal should then be capable ofsending and receiving information

A connection between a service provider and a user goes through a hub (for collecting services)

or a feeder station (e.g for broadcasting services) A connection from a gateway, hub or feederstation to a user terminal is called a forward connection The reverse connection is the returnconnection Both forward and return connections entail an uplink and a downlink, and possiblyone or more intersatellite links

1.3.1 Communications links

A link between transmitting equipment and receiving equipment consists of a radio or opticalmodulated carrier The performance of the transmitting equipment is measured by its effectiveisotropic radiated power (EIRP), which is the power fed to the antenna multiplied by the gain of theantenna in the considered direction The performance of the receiving equipment is measured

by G/T, the ratio of the antenna receive gain, G, in the considered direction and the system noisetemperature, T; G/T is called the receiver’s figure of merit These concepts are detailed in Chapter 5.The types of link shown in Figure 1.1 are:

— the uplinks from the earth stations to the satellites;

— the downlinks from the satellites to the earth stations;

— the intersatellite links, between the satellites

Table 1.1 Services from different types of traffic earth station

Point-to-point Gateway, hub 2–10

Broadcast/multicast Feeder station 1–5

VSAT 0.5–1.0Collect VSAT 0.1–1.0

Mobile Handset, portable, mobile 0.1–0.5

Gateway 2–10

Uplinks and downlinks consist of radio frequency modulated carriers, while intersatellite links can

be either radio frequency or optical Carriers are modulated by baseband signals conveyinginformation for communications purposes

The link performance can be measured by the ratio of the received carrier power, C, to the noise

the quality of service, specified in terms of bit error rate (BER) for digital communications.Another parameter of importance for the design of a link is the bandwidth, B, occupied bythe carrier This bandwidth depends on the information data rate, the channel coding rate(forward error correction) and the type of modulation used to modulate the carrier For satellitelinks, the trade-off between required carrier power and occupied bandwidth is paramount tothe cost-effective design of the link This is an important aspect of satellite communications aspower impacts both satellite mass and earth station size, and bandwidth is constrained byregulations Moreover, a service provider who rents satellite transponder capacity from thesatellite operator is charged according to the highest share of either power or bandwidthresource available from the satellite transponder The service provider’s revenue is based onthe number of established connections, so the objective is to maximise the throughput of theconsidered link while keeping a balanced share of power and bandwidth usage This is discussed

in Chapter 4

In a satellite system, several stations transmit their carriers to a given satellite, therefore thesatellite acts as a network node The techniques used to organise the access to the satellite by thecarriers are called multiple access techniques (Chapter 6)

1.3.2 The space segmentThe satellite consists of the payload and the platform The payload consists of the receiving andtransmitting antennas and all the electronic equipment which supports the transmission of thecarriers The two types of payload organisation are illustrated in Figure 1.2

Figure 1.2a shows a transparent payload (sometimes called a ‘bent pipe’ type) where carrierpower is amplified and frequency is downconverted Power gain is of the order of 100–130 dB,required to raise the power level of the received carrier from a few tens of picowatts to the powerlevel of the carrier fed to the transmit antenna of a few watts to a few tens of watts Frequencyconversion is required to increase isolation between the receiving input and the transmittingoutput Due to technology power limitations, the overall satellite payload bandwidth is split intoseveral sub-bands, the carriers in each sub-band being amplified by a dedicated power amplifier.The amplifying chain associated with each sub-band is called a satellite channel, or transponder Thebandwidth splitting is achieved using a set of filters called the input multiplexer (IMUX) Theamplified carriers are recombined in the output multiplexer (OMUX)

The transparent payload in Figure 1.2a belongs to a single beam satellite where each transmitand receive antenna generates one beam only One could also consider multiple beam antennas.The payload would then have as many inputs/outputs as upbeams/downbeams Routing ofcarriers from one upbeam to a given downbeam implies either routing through different satellitechannels, transponder hopping, depending on the selected uplink frequency or on-board switchingwith transparent on-board processing These techniques are presented in Chapter 7

Figure 1.2b shows a multiple beam regenerative payload where the uplink carriers are dulated The availability of the baseband signals allows on-board processing and routing ofinformation from upbeam to downbeam through on-board switching at baseband The frequencyconversion is achieved by modulating on-board-generated carriers at downlink frequency Themodulated carriers are then amplified and delivered to the destination downbeam

demo-Figure 1.3 illustrates a multiple beam satellite antenna and its associated coverage areas.Each beam defines a beam coverage area, also called footprint, on the earth surface The aggregate

beam coverage areas define the multibeam antenna coverage area A given satellite may have severalmultiple beam antennas, and their combined coverage defines the satellite coverage area.

Figure 1.4 illustrates the concept of instantaneous system coverage and long-term coverage Theinstantaneous system coverage consists of the aggregation at a given time of the coverage areas ofthe individual satellites participating in the constellation The long-term coverage is the area on theearth scanned over time by the antennas of the satellites in the constellation

The coverage area should encompass the service zone, which corresponds to the geographicalregion where the stations are installed For real-time services, the instantaneous system coverage

Figure 1.2 Payload organisation: (a) transparent and (b) regenerative.

Figure 1.4 Types of coverage.

beam coverage

multibeam antennacoverage

Satellite antenna

Figure 1.3 Multiple beam satellite antenna and associated coverage area.

should at any time have a footprint covering the service zone, while for non-real-time and-forward) services, it should have long-term coverage of the service zone.

(store-The platform consists of all the subsystems which permit the payload to operate Table 1.2 liststhese subsystems and indicates their respective main functions and characteristics

The detailed architecture and technology of the payload equipment are explained in Chapter 9.The architecture and technologies of the platform are considered in Chapter 10 The operations

of orbit injection and the various types of launcher are the subject of Chapter 11 The spaceenvironment and its effects on the satellite are presented in Chapter 12

To ensure a service with a specified availability, a satellite communication system must makeuse of several satellites in order to ensure redundancy A satellite can cease to be available due to afailure or because it has reached the end of its lifetime In this respect it is necessary to distinguishbetween the reliability and the lifetime of a satellite Reliability is a measure of the probability of

a breakdown and depends on the reliability of the equipment and any schemes to provideredundancy The lifetime is conditioned by the ability to maintain the satellite on station in thenominal attitude, and depends on the quantity of fuel available for the propulsion system andattitude and orbit control In a system, provision is generally made for an operational satellite,

a backup satellite in orbit and a backup satellite on the ground The reliability of the systemwill involve not only the reliability of each of the satellites but also the reliability of launching

An approach to these problems is treated in Chapter 13

1.3.3 The ground segmentThe ground segment consists of all the earth stations; these are most often connected to the end-user’s terminal by a terrestrial network or, in the case of small stations (Very Small ApertureTerminal, VSAT), directly connected to the end-user’s terminal Stations are distinguished by theirsize which varies according to the volume of traffic to be carried on the satellite link and the type

of traffic (telephone, television or data) In the past, the largest were equipped with antennas of

30 m diameter (Standard A of the INTELSAT network) The smallest have 0.6 m antennas(receiving stations from direct broadcasting satellites) or even smaller (0.1 m) antennas (mobilestations, portable stations or handsets) Some stations both transmit and receive Others are receive-only (RCVO) stations; this is the case, for example, with receiving stations for a broadcastingsatellite system or a distribution system for television or data signals Figure 1.5 shows the typicalarchitecture of an earth station for both transmission and reception Chapter 5 introducesthe characteristic parameters of the earth station which appear in the link budget calculations.Chapter 3 presents the characteristics of signals supplied to earth stations by the user terminaleither directly or through a terrestrial network, the signal processing at the station (such as sourcecoding and compression, multiplexing, digital speech interpolation, channel coding, scrambling

Table 1.2 Platform subsystem

Attitude and orbit control

(AOCS)

Attitude stabilisation, orbitdetermination

AccuracyPropulsion Provision of velocity increments Specific impulse, mass of

propellantElectric power supply Provision of electrical energy Power, voltage stabilityTelemetry, tracking and

command (TTC)

Exchange of housekeepinginformation

Number of channels, security ofcommunications

Thermal control Temperature maintenance Dissipation capability

Structure Equipment support Rigidity, lightness

and encryption), and transmission and reception (including modulation and demodulation).Chapter 8 treats the organisation and equipment of earth stations.

1.4 TYPES OF ORBITThe orbit is the trajectory followed by the satellite The trajectory is within a plane and shaped as

an ellipse with a maximum extension at the apogee and a minimum at the perigee The satellitemoves more slowly in its trajectory as the distance from the earth increases Chapter 2 provides

a definition of the orbital parameters

The most favourable orbits are as follows:

is particularly stable with respect to irregularities in terrestrial gravitational potential and,owing to its inclination, enables the satellite to cover regions of high latitude for a large fraction

of the orbital period as it passes to the apogee This type of orbit has been adopted by the USSRfor the satellites of the MOLNYA system with period of 12 hours Figure 1.6 shows the geometry

of the orbit The satellite remains above the regions located under the apogee for a time interval

of the order of 8 hours Continuous coverage can be ensured with three phased satellites ondifferent orbits Several studies relate to elliptical orbits with a period of 24 h (TUNDRA orbits)

or a multiple of 24 h These orbits are particularly useful for satellite systems for communicationwith mobiles where the masking effects caused by surrounding obstacles such as buildings

Antenna axis

Elevation angle E

Local horizon

Baseband signals(from users)

Baseband signals(to users)

POWERSUPPLY

TRACKING

MONITORING

&

CONTROLDIPLEXER

IFMODULATOR

IFDEMODULATOR

RF– FRONT END(low noise amp)

RFHIGH POWERAMPLIFIER

Figure 1.5 The organisation of an earth station RF ¼ radio frequency, IF ¼ intermediate frequency.

In fact, inclined elliptic orbits can provide the possibility of links at medium latitudes when

cannot be provided at the same latitudes by geostationary satellites In the late 1980s, theEuropean Space Agency (ESA) studied the use of elliptical highly inclined orbits (HEO) fordigital audio broadcasting (DAB) and mobile communications in the framework of its Archi-medes programme The concept became reality at the end of the 1990s with the Sirius systemdelivering satellite digital audio radio services to millions of subscribers (mainly automobiles)

in the United States using three satellites on HEO Tundra-like orbits [AKT-08]

— Circular low earth orbits (LEO) The altitude of the satellite is constant and equal to several

inclination, this type of orbit guarantees worldwide long term coverage as a result of thecombined motion of the satellite and earth rotation, as shown in Figure 1.7 This is the reason forchoosing this type of orbit for observation satellites (for example, the SPOT satellite: altitude

store-and-forward communications if the satellite is equipped with a means of storing information

A constellation of several tens of satellites in low altitude (e.g IRIDIUM with 66 satellites at

780 km) circular orbits can provide worldwide real-time communication Non-polar orbits

Figure 1.6 The orbit of a MOLNYA satellite.