Dennis Roddy
i
Satellite Communications
Dennis Roddy
Fourth Edition
McGraw-Hill
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Dennis Roddy
ii
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Dennis Roddy
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Contents
Preface xi
Chapter 1. Overview of Satellite Systems 1
1.1 Introduction 1
1.2 Frequency Allocations for Satellite Services 2
1.3 INTELSAT 4
1.4 U.S. Domsats 9
1.5 Polar Orbiting Satellites 12
1.6 Argos System 18
1.7 Cospas-Sarsat 19
1.8 Problems 25
References 26
Chapter 2. Orbits and Launching Methods 29
2.1 Introduction 29
2.2 Kepler’s First Law 29
2.3 Kepler’s Second Law 30
2.4 Kepler’s Third Law 31
2.5 Definitions of Terms for Earth-Orbiting Satellites 32
2.6 Orbital Elements 35
2.7 Apogee and Perigee Heights 37
2.8 Orbit Perturbations 38
2.8.1 Effects of a nonspherical earth 38
2.8.2 Atmospheric drag 43
2.9 Inclined Orbits 44
2.9.1 Calendars 45

2.9.2 Universal time 46
2.9.3 Julian dates 47
2.9.4 Sidereal time 49
2.9.5 The orbital plane 50
2.9.6 The geocentric-equatorial coordinate system 54
2.9.7 Earth station referred to the IJK frame 56
2.9.8 The topocentric-horizon coordinate system 62
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2.9.9 The subsatellite point 64
2.9.10 Predicting satellite position 66
2.10 Local Mean Solar Time and Sun-Synchronous Orbits 66
2.11 Standard Time 70
2.12 Problems 71
References 75
Chapter 3. The Geostationary Orbit 77
3.1 Introduction 77
3.2 Antenna Look Angles 78
3.3 The Polar Mount Antenna 85
3.4 Limits of Visibility 87
3.5 Near Geostationary Orbits 89
3.6 Earth Eclipse of Satellite 92
3.7 Sun Transit Outage 94
3.8 Launching Orbits 94
3.9 Problems 99
References 101
Chapter 4. Radio Wave Propagation 103
4.1 Introduction 103
4.2 Atmospheric Losses 103
4.3 Ionospheric Effects 104

4.4 Rain Attenuation 106
4.5 Other Propagation Impairments 111
4.6 Problems and Exercises 111
References 112
Chapter 5. Polarization 115
5.1 Introduction 115
5.2 Antenna Polarization 120
5.3 Polarization of Satellite Signals 123
5.4 Cross-Polarization Discrimination 128
5.5 Ionospheric Depolarization 130
5.6 Rain Depolarization 131
5.7 Ice Depolarization 133
5.8 Problems and Exercises 133
References 136
Chapter 6. Antennas 137
6.1 Introduction 137
6.2 Reciprocity Theorem for Antennas 138
6.3 Coordinate System 139
6.4 The Radiated Fields 140
6.5 Power Flux Density 144
6.6 The Isotropic Radiator and Antenna Gain 144
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6.7 Radiation Pattern 145
6.8 Beam Solid Angle and Directivity 146
6.9 Effective Aperture 148
6.10 The Half-Wave Dipole 149
6.11 Aperture Antennas 151
6.12 Horn Antennas 155
6.12.1 Conical horn antennas 155

6.12.2 Pyramidal horn antennas 158
6.13 The Parabolic Reflector 159
6.14 The Offset Feed 165
6.15 Double-Reflector Antennas 167
6.15.1 Cassegrain antenna 167
6.15.2 Gregorian antenna 169
6.16 Shaped Reflector Systems 169
6.17 Arrays 172
6.18 Planar Antennas 177
6.19 Planar Arrays 180
6.20 Reflectarrays 187
6.21 Array Switching 188
6.22 Problems and Exercises 193
References 196
Chapter 7. The Space Segment 199
7.1 Introduction 199
7.2 The Power Supply 199
7.3 Attitude Control 202
7.3.1 Spinning satellite stabilization 204
7.3.2 Momentum wheel stabilization 206
7.4 Station Keeping 209
7.5 Thermal Control 211
7.6 TT&C Subsystem 212
7.7 Transponders 213
7.7.1 The wideband receiver 215
7.7.2 The input demultiplexer 218
7.7.3 The power amplifier 218
7.8 The Antenna Subs
y
ste

m
225
7.9 Morelos and Satmex 5 227
7.10 Anik-Satellites 231
7.11 Advanced Tiros-N Spacecraft 232
7.12 Problems and Exercises 235
References 236
Chapter 8. The Earth Segment 239
8.1 Introduction 239
8.2 Receive-Only Home TV Systems 239
8.2.1 The outdoor unit 241
8.2.2 The indoor unit for analog (FM) TV 242
8.3 Master Antenna TV System 243
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8.4 Community Antenna TV System 244
8.5 Transmit-Receive Earth Stations 246
8.6 Problems and Exercises 250
References 251
Chapter 9. Analog Signals 253
9.1 Introduction 253
9.2 The Telephone Channel 253
9.3 Single-Sideband Telephony 254
9.4 FDM Telephony 256
9.5 Color Television 258
9.6 Frequency Modulation 265
9.6.1 Limiters 266
9.6.2 Bandwidth 266
9.6.3 FM detector noise and processing gain 269
9.6.4 Signal-to-noise ratio 272

9.6.5 Preemphasis and deemphasis 273
9.6.6 Noise weighting 274
9.6.7 S/N and bandwidth for FDM/FM telephony
276
9.6.8 Signal-to-noise ratio for TV/FM 278
9.7 Problems and Exercises 279
References 281
Chapter 10. Digital Signals 283
10.1 Introduction 283
10.2 Digital Baseband Signals 283
10.3 Pulse Code Modulation 288
10.4 Time-Division Multiplexing 292
10.5 Bandwidth Requirements 293
10.6 Digital Carrier Systems 296
10.6.1 Binary phase-shift keying 298
10.6.2 Quadrature phase-shift keying 300
10.6.3 Transmission rate and bandwidth for PSK modulation 302
10.6.4 Bit error rate for PSK modulation 303
10.7 Carrier Recovery Circuits 309
10.8 Bit Timing Recovery 310
10.9 Problems and Exercises 311
References 313
Chapter 11. Error Control Coding 315
11.1 Introduction 315
11.2 Linear Block Codes 316
11.3 Cyclic Codes 321
11.3.1 Hamming codes 321
11.3.2 BCH codes 322
11.3.3 Reed-Solomon codes 322
11.4 Convolution Codes 324

11.5 Interleaving 328
11.6 Concatenated Codes 330
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11.7 Link Parameters Affected by Coding 331
11.8 Coding Gain 333
11.9 Hard Decision and Soft Decision Decoding 334
11.10 Shannon Capacity 336
11.11 Turbo Codes and LDPC Codes 338
11.11.1 Low density parity check (LDPC) codes 341
11.12 Automatic Repeat Request (ARQ) 344
11.13 Problems and Exercises 346
References 348
Chapter
12.
The Space Link 351
12.1 Introduction 351
12.2 Equivalent Isotropic Radiated Power 351
12.3 Transmission Losses 352
12.3.1 Free-space transmission 353
12.3.2 Feeder losses 354
12.3.3 Antenna misalignment losses 355
12.3.4 Fixed atmospheric and ionospheric losses 356
12.4 The Link-Power Budget Equation 356
12.5 System Noise 357
12.5.1 Antenna noise 358
12.5.2 Amplifier noise temperature 360
12.5.3 Amplifiers in cascade 361
12.5.4 Noise factor 362
12.5.5 Noise temperature of absorptive networks 363

12.5.6 Overall system noise temperature 365
12.6 Carrier-to-Noise Ratio 366
12.7 The Uplink 367
12.7.1 Saturation flux density 368
12.7.2 Input backoff 370
12.7.3 The earth station HPA 371
12.8 Downlink 371
12.8.1 Output back-off 373
12.8.2 Satellite TWTA output 374
12.9 Effects of Rai
n
375
12.9.1 Uplink rain-fade margin 377
12.9.2 Downlink rain-fade margin 377
12.10 Combined Uplink and Downlink C/N Ratio
380
12.11 Intermodulation Noise 383
12.12 Inter-Satellite Links 384
12.13 Problems and Exercises 393
References 397
Chapter
13.
Interference 399
13.1 Introduction 399
13.2 Interference between Satellite Circuits (B
1
and B
2
Modes)
401

13.2.1 Downlink 403
13.2.2 Uplink 404
13.2.3 Combined [C/I] due to interference on both uplink and
downlink
405
13.2.4 Antenna gain function 405
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13.2.5 Passband interference 407
13.2.6 Receiver transfer characteristic 408
13.2.7 Specified interference objectives 409
13.2.8 Protection ratio 410
13.3 Energy Dispersal 411
13.4 Coordination 413
13.4.1 Interference levels 413
13.4.2 Transmission gain 415
13.4.3 Resulting noise-temperature rise 416
13.4.4 Coordination criterion 417
13.4.5 Noise power spectral density 418
13.5 Problems and Exercises 419
References 421
Chapter
14.
Satellite Access 423
14.1 Introduction 423
14.2 Single Access 424
14.3 Preassigned FDMA 425
14.4 Demand-Assigned FDMA 430
14.5 Spade System 430
14.6 Bandwidth-Limited and Power-Limited TWT Amplifier

Operation
432
14.6.1 FDMA downlink analysis 433
14.7 TDMA 436
14.7.1 Reference burst 440
14.7.2 Preamble and postamble 442
14.7.3 Carrier recovery 443
14.7.4 Network synchronization 444
14.7.5 Unique word detection 448
14.7.6 Traffic data 451
14.7.7 Frame efficiency and channel capacity 451
14.7.8 Preassigned TDMA 452
14.7.9 Demand-assigned TDMA 455
14.7.10 Speech interpolation and prediction 455
14.7.11 Downlink analysis for digital transmission 459
14.7.12 Comparison of uplink power requirements for FDMA and
TDMA
461
14.8 On-Board Signal Processing for FDMA/TDM Operation 463
14.9 Satellite-Switched TDMA 467
14.10 Code-Division Multiple Access 472
14.10.1 Direct-sequence spread spectrum 473
14.10.2 The code signal c(t)
473
14.10.3 Acquisition and tracking 477
14.10.4 Spectrum spreading and despreading 478
14.10.5 CDMA throughput 481
14.11 Problems and Exercises 483
References 488
Chapter

15.
Satellites in Networks 491
15.1 Introduction 491
15.2 Bandwidth 492
15.3 Network Basics 492
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15.4 Asynchronous Transfer Mode (ATM) 494
15.4.1 ATM layers 495
15.4.2 ATM networks and interfaces 497
15.4.3 The ATM cell and header 497
15.4.4 ATM switching 499
15.4.5 Permanent and switched virtual circuits 501
15.4.6 ATM bandwidth 501
15.4.7 Quality of service 504
15.5 ATM over Satellite 504
15.6 The Internet 511
15.7 Internet Layers 513
15.8 The TCP Link 516
15.9 Satellite Links and TCP 517
15.10 Enhancing TCP Over Satellite Channels Using Standard
Mechanisms (RFC-2488)
519
15.11 Requests for Comments 521
15.12 Split TCP Connections 522
15.13 Asymmetric Channels 525
15.14 Proposed Systems 527
15.15 Problems and Exercises 527
References 530
Chapter

16.
Direct Broadcast Satellite (DBS) Television 531
16.1 Introduction 531
16.2 Orbital Spacing 531
16.3 Power Rating and Number of Transponders 533
16.4 Frequencies and Polarization 533
16.5 Transponder Capacity 533
16.6 Bit Rates for Digital Television 534
16.7 MPEG Compression Standards 536
16.8 Forward Error Correction (FEC) 541
16.9 The Home Receiver Outdoor Unit (ODU) 542
16.10 The Home Receiver Indoor Unit (IDU) 544
16.11 Downlink Analysis 546
16.12 Uplink 553
16.13 Hi
g
h Definition Television (HDTV) 554
16.13.1 HDTV displays 554
16.14 Video Frequency Bandwidth 555
16.15 Problems and Exercises 557
References 560
Chapter
17.
Satellite Mobile and Specialized Services 561
17.1 Introduction 561
17.2 Satellite Mobile Services 562
17.3 VSATs 564
17.4 Radarsat 566
17.5 Global Positioning Satellite System (GPS) 569
17.6 Orbcomm 572

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17.7 Iridium 576
17.8 Problems and Exercises 582
References 583
Appendix A. Answers to Selected Problems 585
Appendix B. Conic Sections 591
Appendix C. NASA Two-Line Orbital Elements 609
Appendix D. Listings of Artificial Satellites 613
Appendix E. Illustrating Third-Order Intermodulation Products 615
Appendix F. Acronyms 617
Appendix G. Logarithmic Units 625
Index 631
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Preface
As with previous editions, the fourth edition provides broad coverage of satellite communications, while
maintaining sufficient depth to lay the foundations for more advanced studies. Mathematics is used as a
descriptive tool and to obtain numerical results, but lengthy mathematical derivations are avoided. In setting
up numerical problems and examples the author has made use of Mathcad
™
, a computer program, but the
worked examples in the text are presented in normal algebraic notation, so that other programs, including
programmable calculators can be used.
The main changes compared to the previous edition are as follows. In Chap. 1 the sections on INTELSAT
and polar orbiting satellites, including environmental and search and rescue, have been updated.
Sun-synchronous orbits have been treated in more detail in Chap. 2. A new section on planar antennas and
arrays, including reflectarrays, and array switching has been added in Chap. 6. Chapter 8 includes additional
details on C-band reception of television signals. In Chap. 11, a more detailed description is given of linear
block codes, and new sections on the Shannon capacity and turbo and low density parity check (LDPC) codes

have been included. Chapter 12 has a new section on intersatellite links (ISLs), including optical links.
Chapter 15 has been extensively rewritten to include more basic details on networks and asynchronous
transfer mode (ATM) operation. Chapter 16 covers high definition television (HDTV) in more detail, and the
Iridium mobile satellite system, which is now under new ownership, is described in Chap. 17.
In this age of heightened security concerns, it has proved difficult to get detailed technical information on
satellite systems and equipment. Special thanks are, therefore, due to the following people and organizations
that provided copies of technical papers, diagrams, and figures for the topics listed:
Planar antennas and arrays, reflectarrays, and array switching: Jacquelyn Adams, Battelle/GLITeC; Dr.
Luigi Boccia, Universita della
Dennis Roddy
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Calabria; Thomas J. Braviak, Director, Marketing Administration, Aeroflex/KDI-Integrated Products; Dr.
Michael Parnes, Ascor, Saint-Petersburg, Russia; Dharmesh Patel, Radar Division Naval Research
Laboratory; Professor David Pozar, Electrical and Computer Engineering, University of Massachusetts at
Amherst; Dr. Bob Romanofsky, Antenna, Microwave, and Optical Systems Branch, NASA Glenn Research
Center; Dr. Peter Schrock, Webmaster/Publications Representative, JPL.
ATM: William D. Ivancic, Glenn Research Center, and Lewis Research Center, NASA; Dr Ing. Petia
Todorova, Fraunhofer Institut FOKUS, Berlin.
Turbo and LDPC codes: Dr. Alister G. Burr, Professor of Communications, Dept. of Electronics, University
of York; Tony Summers, Senior Applications Engineer, Comtech AHA.
HDTV: Cathy Firebrace, Information Officer, the IEE, London U.K.
INTELSAT: Travis S. Taylor, Corporate Communications, Intelsat, Washington, DC.
Iridium system: Liz DeCastro, Corporate Communications Director, Iridium Satellite.
Cospas-Sarsat: Cheryl Bertoia, Principal Operations Officer, Deputy Head, Cospas-Sarsat Secretariat,
London, U.K., and Hannah Bermudez also of the Cospas-Sarsat Secretariat.
And from the third edition, thanks to Dr. Henry Driver of Computer Sciences Corporation for details
relating to the calculation of geodetic position in Chap. 2. Thanks also to the users and reviewers who made
suggestions for corrections, additions, and improvements. Errors should not occur, but they do, and the author
would be grateful if these are drawn to his attention. He can be reached at
The editorial team at McGraw-Hill has contributed a great deal in getting the fourth edition into print:

thanks are due to Steve Chapman, the sponsoring editor; Diana Mattingly, editorial assistant; and Gita Raman,
project manager, for their help, and their gentle but persistent reminders to keep the book on schedule.
Dennis Roddy
Thunder Bay, Ontario
1
Chapter
1
Overview of Satellite Systems
1.1 Introduction
The use of satellites in communications systems is very much a fact of
everyday life, as is evidenced by the many homes equipped with anten-
nas, or “dishes,” used for reception of satellite television. What may not
be so well known is that satellites form an essential part of telecom-
munications systems worldwide, carrying large amounts of data and
telephone traffic in addition to television signals.
Satellites offer a number of features not readily available with other
means of communications. Because very large areas of the earth are vis-
ible from a satellite, the satellite can form the star point of a commu-
nications net, simultaneously linking many users who may be widely
separated geographically. The same feature enables satellites to provide
communications links to remote communities in sparsely populated
areas that are difficult to access by other means. Of course, satellite sig-
nals ignore political boundaries as well as geographic ones, which may
or may not be a desirable feature.
To give some idea of cost, the construction and launch cost of the
Canadian Anik-E1 satellite (in 1994 Canadian dollars) was $281.2
million, and that of the Anik-E2, $290.5 million. The combined launch
insurance for both satellites was $95.5 million. A feature of any satel-
lite system is that the cost is distance insensitive, meaning that it
costs about the same to provide a satellite communications link over

a short distance as it does over a large distance. Thus a satellite com-
munications system is economical only where the system is in contin-
uous use and the costs can be reasonably spread over a large number
of users.
Satellites are also used for remote sensing, examples being the
detection of water pollution and the monitoring and reporting of
2 Chapter One
weather conditions. Some of these remote sensing satellites also form
a vital link in search and rescue operations for downed aircraft and
the like.
A good overview of the role of satellites is given by Pritchard (1984)
and Brown (1981). To provide a general overview of satellite systems
here, three different types of applications are briefly described in this
chapter: (1) the largest international system, Intelsat, (2) the domestic
satellite system in the United States, Domsat, and (3) U.S. National
Oceanographic and Atmospheric Administration (NOAA) series of polar
orbiting satellites used for environmental monitoring and search and
rescue.
1.2 Frequency Allocations
for Satellite Services
Allocating frequencies to satellite services is a complicated process
which requires international coordination and planning. This is car-
ried out under the auspices of the International Telecommunication
Union (ITU).
To facilitate frequency planning, the world is divided into three
regions:
Region 1: Europe, Africa, what was formerly the Soviet Union, and
Mongolia
Region 2: North and South America and Greenland
Region 3: Asia (excluding region 1 areas), Australia, and the south-

west Pacific
Within these regions, frequency bands are allocated to various satel-
lite services, although a given service may be allocated different fre-
quency bands in different regions. Some of the services provided by
satellites are:
Fixed satellite service (FSS)
Broadcasting satellite service (BSS)
Mobile satellite services
Navigational satellite services
Meteorological satellite services
There are many subdivisions within these broad classifications;
for example, the FSS provides links for existing telephone networks
as well as for transmitting television signals to cable companies for
distribution over cable systems. Broadcasting satellite services are
intended mainly for direct broadcast to the home, sometimes referred
Overview of Satellite Systems 3
to as direct broadcast satellite (DBS) service [in Europe it may be known
as direct-to-home (DTH) service]. Mobile satellite services would include
land mobile, maritime mobile, and aeronautical mobile. Navigational
satellite services include global positioning systems (GPS), and satel-
lites intended for the meteorological services often provide a search
and rescue service.
Table 1.1 lists the frequency band designations in common use for
satellite services. The Ku band signifies the band under the K band, and
the Ka band is the band above the K band. The Ku band is the one used
at present for DBS, and it is also used for certain FSS. The C band is
used for FSS, and no DBS is allowed in this band. The very high fre-
quency (VHF) band is used for certain mobile and navigational services
and for data transfer from weather satellites. The L band is used for
mobile satellite services and navigation systems. For the FSS in the C

band, the most widely used subrange is approximately 4 to 6 GHz. The
higher frequency is nearly always used for the uplink to the satellite,
for reasons that will be explained later, and common practice is to denote
the C band by 6/4 GHz, giving the uplink frequency first. For the direct
broadcast service in the Ku band, the most widely used range is approxi-
mately 12 to 14 GHz, which is denoted by 14/12 GHz. Although frequency
assignments are made much more precisely, and they may lie somewhat
outside the values quoted here (an example of assigned frequencies in
the Ku band is 14,030 and 11,730 MHz), the approximate values stated
are quite satisfactory for use in calculations involving frequency, as will
be shown later in the text.
Care must be exercised when using published references to frequency
bands, because the designations have been developed somewhat differ-
ently for radar and communications applications; in addition, not all
countries use the same designations.
TABLE 1.1 Frequency Band Designations
Frequency range, (GHz) Band designation
0.1–0.3 VHF
0.3–1.0 UHF
1.0–2.0 L
2.0–4.0 S
4.0–8.0 C
8.0–12.0 X
12.0–18.0 Ku
18.0–27.0 K
27.0–40.0 Ka
40.0–75 V
75–110 W
110–300 mm
300–3000 μm

The official ITU frequency band designations are shown in Table 1.2 for
completeness. However, in this text the designations given in Table 1.1 will
be used, along with 6/4 GHz for the C band and 14/12 GHz for the Ku band.
1.3 INTELSAT
INTELSAT stands for International Telecommunications Satellite. The
organization was created in 1964 and currently has over 140 member
countries and more than 40 investing entities (see />for more details). In July 2001 INTELSAT became a private company
and in May 2002 the company began providing end-to-end solutions
through a network of teleports, leased fiber, and points of presence (PoPs)
around the globe. Starting with the Early Bird satellite in 1965, a succes-
sion of satellites has been launched at intervals of a few years. Figure 1.1
illustrates the evolution of some of the INTELSAT satellites. As the
figure shows, the capacity, in terms of number of voice channels,
increased dramatically with each succeeding launch, as well as the
design lifetime. These satellites are in geostationary orbit, meaning that
they appear to be stationary in relation to the earth. The geostationary
orbit is the topic of Chap. 3. At this point it may be noted that geosta-
tionary satellites orbit in the earth’s equatorial plane and their position
is specified by their longitude. For international traffic, INTELSAT
covers three main regions—the Atlantic Ocean Region (AOR), the Indian
Ocean Region (IOR), and the Pacific Ocean Region (POR) and what is
termed Intelsat America’s Region. For the ocean regions the satellites
are positioned in geostationary orbit above the particular ocean, where
they provide a transoceanic telecommunications route. For example,
INTELSAT satellite 905 is positioned at 335.5° east longitude. The foot-
prints for the C-band antennas are shown in Fig. 1.2a, and for the Ku-
band spot beam antennas in Figs. 1.2b and c.
4 Chapter One
TABLE 1.2 ITU Frequency Band Designations
Frequency range Metric

(lower limit Corresponding abbreviations
Band exclusive, upper metric for the
number Symbols limit inclusive) subdivision bands
4 VLF 3–30 kHz Myriametric waves B.Mam
5 LF 30–300 kHz Kilometric waves B.km
6 MF 300–3000 kHz Hectometric waves B.hm
7 HF 3–30 MHz Decametric waves B.dam
8 VHF 30–300 MHz Metric waves B.m
9 UHF 300–3000 MHz Decimetric waves B.dm
10 SHF 3–30 GHz Centimetric waves B.cm
11 EHF 30–300 GHz Millimetric waves B.mm
12 300–3000 GHz Decimillimetric waves
SOURCE: ITU Geneva.
Figure 1.1 Evolution of INTELSAT satellites. (From Colino 1985; courtesy of ITU T
elecommunications Journal.)
5