SATELLITE COMMUNICATIONS SYSTEMS

Transcription

1 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 ГAeronautique 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 WILEY A John Wiley and Sons, Ltd, Publication

2 CONTENTS ACKNOWLEDGEMENT ACRONYMS NOTATION xv xvii xxv 1 INTRODUCTION l 1.1 Birth of satellite communications Development of satellite communications Configuration of a satellite communications system Communications links The space segment The ground segment Types of orbit Radio regulations The ITU organisation Space radiocommunications services Frequency allocation Technology trends Services The way forward 17 References 18 2 ORBITS AND RELATED ISSUES Keplerian orbits Kepler's laws Newton's law Relative movement of two point bodies Orbital parameters The earth's orbit Earth-satellite geometry Eclipses of the sun Sun-satellite conjunction Useful orbits for satellite communication Elliptical orbits with non-zero inclination Geosynchronous elliptic orbits with zero inclination Geosynchronous circular orbits with non-zero inclination Sub-synchronous circular orbits with zero inclination Geostationary satellite orbits 59

3 VI Contents 2.3 Perturbations of orbits The nature of the perturbations The effect of perturbations; orbit perturbation Perturbations of the orbit of geostationary satellites Orbit corrections: station keeping of geostationary satellites Conclusion 97 References 97 BASEBAND SIGNALS AND QUALITY OF SERVICE Baseband signals Digital telephone signal Sound signals Television signals Data and multimedia signals Performance objectives Telephone Sound Television Data Availability objectives Delay Delay in terrestrial network Propagation delay over satellite links Baseband-signal processing time Protocol-induced delay Conclusion 112 References 113 DIGITAL COMMUNICATIONS TECHNIQUES Baseband formatting Encryption Scrambling Digital modulation Two-state modulation BPSK and DE-BPSK Four-state modulation QPSK Variants of QPSK Higher-order PSK and APSK Spectrum of unfiltered modulated carriers Demodulation Modulation spectral efficiency Channel coding Block encoding and convolutional encoding Channel decoding Concatenated encoding Interleaving Channel coding and the power-bandwidth trade-off Coding with variable bandwidth Coding with constant bandwidth Example: Downlink coding with on-board regeneration Conclusion 139

4 Contents vii 4.5 Coded modulation Trellis coded modulation Block coded modulation Decoding coded modulation Multilevel trellis coded modulation TCM using a multidimensional signal set Performance of coded modulations End-to-end error control Digital video broadcasting via satellite (DVB-S) Transmission system Error performance requirements Second generation DVB-S New technology in DVB-S Transmission system architecture Error performance Conclusion Digital transmission of telephony Digital broadcasting of television 159 References 160 UPLINK, DOWNLINK AND OVERALL LINK PERFORMANCE; INTERSATELLITE LINKS Configuration of a link Antenna parameters Gain Radiation pattern and angular beamwidth Polarisation Radiated power Effective isotropic radiated power (EIRP) Power flux density Received signal power Power captured by the receiving antenna and free space loss Example 1: Uplink received power Example 2: Downlink received power Additional losses Conclusion Noise power spectral density at the receiver input The origins of noise Noise characterisation Noise temperature of an antenna System noise temperature System noise temperature: Example Conclusion Individual link performance Carrier power to noise power spectral density ratio at receiver input Clear sky uplink performance Clear sky downlink performance Influence of the atmosphere Impairments caused by rain Other impairments Link impairments relative importance 209

5 viii Contents 5.7A Link performance under rain conditions Conclusion Mitigation of atmospheric impairments Depolarisation mitigation Attenuation mitigation Site diversity Adaptivity Cost-availability trade-off Overall link performance with transparent satellite Characteristics of the satellite channel Expression for (C/N 0 )T Overall link performance for a transparent satellite without interference or intermodulation Overall link performance with regenerative satellite Linear satellite channel without interference Non-linear satellite channel without interference Non-linear satellite channel with interference Link performance with multibeam antenna coverage vs monobeam coverage Advantages of multibeam coverage Disadvantages of multibeam coverage Conclusion Intersatellite link performance Frequency bands Radio-frequency links Optical links Conclusion 245 References 246 MULTIPLE ACCESS Layered data transmission Traffic parameters Traffic intensity Call blocking probability Burstiness Traffic routing One carrier per station-to-station link One carrier per transmitting station Comparison Access techniques Access to a particular satellite channel (or transponder) Multiple access to the satellite channel Performance evaluation efficiency Frequency division multiple access (FDMA) TDM/PSK/FDMA SCPC/FDMA Adjacent channel interference Intermodulation FDMA efficiency Conclusion 260

6 Contents ix 6.6 Time division multiple access (TDMA) Burst generation Frame structure Burst reception Synchronisation TDMA efficiency Conclusion Code division multiple access (CDMA) Direct sequence (DS-CDMA) Frequency hopping CDMA (FH-CDMA) Code generation Synchronisation CDMA efficiency Conclusion Fixed and on-demand assignment The principle Comparison between fixed and on-demand assignment Centralised or distributed management of on-demand assignment Conclusion Random access Asynchronous protocols Protocols with synchronisation Protocols with assignment on demand Conclusion 290 References 291 SATELLITE NETWORKS Network reference models and protocols Layering principle Open Systems Interconnection (OSI) reference model IP reference model Reference architecture for satellite networks Basic characteristics of satellite networks Satellite network topology Types of link Connectivity Satellite on-board connectivity On-board connectivity with transponder hopping On-board connectivity with transparent processing On-board connectivity with regenerative processing On-board connectivity with beam scanning Connectivity through intersatellite links (ISL) Links between geostationary and low earth orbit satellites (GEO-LEO) Links between geostationary satellites (GEO-GEO) Links between low earth orbit satellites (LEO-LEO) Conclusion Satellite broadcast networks Single uplink (one programme) per satellite channel Several programmes per satellite channel Single uplink with time division multiplex (TDM) of programmes Multiple uplinks with time division multiplex (TDM) of programmes on downlink 322

7 X Contents 7.7 Broadband satellite networks Overview of DVB-RCS and DVB-S/S2 network Protocol stack architecture for broadband satellite networks Physical layer Satellite MAC layer Satellite link control layer Quality of service Network layer Regenerative satellite mesh network architecture Transmission control protocol TCP segment header format Connection set up and data transmission Congestion control and flow control Impact of satellite channel characteristics on TCP TCP performance enhancement IPv6 over satellite networks IPv6 basics IPv6 transitions IPv6 tunnelling through satellite networks to4 translation via satellite networks Conclusion 359 References 360 EARTH STATIONS Station organisation Radio-frequency characteristics Effective isotropic radiated power (EIRP) Figure of merit of the station Standards defined by international organisations and satellite operators The antenna subsystem Radiation characteristics (main lobe) Side-lobe radiation Antenna noise temperature Types of antenna Pointing angles of an earth station antenna Mountings to permit antenna pointing Tracking The radio-frequency subsystem Receiving equipment Transmission equipment Redundancy Communication subsystems Frequency translation Amplification, filtering and equalisation Modems The network interface subsystem Multiplexing and demultiplexing Digital speech interpolation (DSD Digital circuit multiplication equipment (DCME) Echo suppression and cancellation Equipment specific to SCPC transmission 432

8 Contents xi 8.7 Monitoring and control; auxiliary equipment Monitoring, alarms and control (MAC) equipment Electrical power Conclusion 433 References 434 THE COMMUNICATION PAYLOAD Mission and characteristics of the payload Functions of the payload Characterisation of the payload The relationship between the radio-frequency characteristics Transparent repeater Characterisation of non-linearities Repeater organisation Equipment characteristics Regenerative repeater Coherent demodulation Differential demodulation Multicarrier demodulation Multibeam antenna payload Fixed interconnection Reconfigurable (semi-fixed) interconnection Transparent on-board time domain switching On-board frequency domain transparent switching Baseband regenerative switching Optical switching Introduction to flexible payloads Solid state equipment technology The environment Analogue microwave component technology Digital component technology Antenna coverage Service zone contour Geometrical contour Global coverage Reduced or spot coverage Evaluation of antenna pointing error Conclusion Antenna characteristics Antenna functions The radio-frequency coverage Circular beams Elliptical beams The influence of depointing Shaped beams Multiple beams Types of antenna Antenna technologies Conclusion 524 References 524

9 xii Contents 10 THE PLATFORM Subsystems Attitude control Attitude control functions Attitude sensors Attitude determination Actuators The principle of gyroscopic stabilisation Spin stabilisation 'Three-axis' stabilisation The propulsion subsystem Characteristics of thrusters Chemical propulsion Electric propulsion Organisation of the propulsion subsystem Electric propulsion for station keeping and orbit transfer The electric power supply Primary energy sources Secondary energy sources Conditioning and protection circuits Example calculations Telemetry, tracking and command (TTC) and on-board data handling (OBDH) Frequencies used The telecommand links Telemetry links Telecommand (TC) and telemetry (TM) message format standards On-board data handling (OBDH) Tracking Thermal control and structure Thermal control specifications Passive control Active control Structure Conclusion Developments and trends 604 References SATELLITE INSTALLATION AND LAUNCH VEHICLES Installation in orbit Basic principles Calculation of the required velocity increments Inclination correction and circularisation The apogee (or perigee) motor Injection into orbit with a conventional launcher Injection into orbit from a quasi-circular low altitude orbit Operations during installation (station acquisition) Injection into orbits other than geostationary The launch window Launch vehicles Brazil China 635

10 Contents хш Commonwealth of Independent States (CIS) Europe India Israel Japan South Korea United States of America Reusable launch vehicles Cost of installation in orbit 661 References THE SPACE ENVIRONMENT Vacuum Characterisation Effects The mechanical environment The gravitational field The earth's magnetic field Solar radiation pressure Meteorites and material particles Torques of internal origin The effect of communication transmissions Conclusions Radiation Solar radiation Earth radiation Thermal effects Effects on materials Flux of high energy particles Cosmic particles Effects on materials The environment during installation The environment during launching Environment in the transfer orbit 677 References RELIABILITY OF SATELLITE COMMUNICATIONS SYSTEMS Introduction of reliability Failure rate The probability of survival or reliability Failure probability or unreliability Mean time to failure (MTTF) Mean satellite lifetime Reliability during the wear-out period Satellite system availability No back-up satellite in orbit Back-up satellite in orbit Conclusion Subsystem reliability Elements in series 685

11 Contents Elements in parallel (static redundancy) Dynamic redundancy (with switching) Equipment having several failure modes Component reliability Component reliability Component selection Manufacture Quality assurance 693 INDEX 697