Digital Telephony and Network Integration

686 Pages·1995·25.769 MB·English

by  Bernhard E. Keiser, Eugene Strange (auth.)

DIGITAL TELEPHONY
AND NETWORK
INTEGRATION
Second Edition
Bernhard E. Keiser
and
Eugene Strange
~
VAN NOSTRAND REINHOLD
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2 3 4 5 6 7 8 9 10 QEBFF 01 00 99 98 97 96 95
Library of Congress Cataloging-in-Publication Data
Keiser, Bernhard, 1928-
Digital telephony and network integration/Bernhard E. Keiser.
Eugene Strange. 2nd ed.
p. cm.
Includes bibliographical references and index.
ISBN 0-442-00901-1
1. Digital telephone systems. I. Strange, Eugene. II. Title. TK6421.K45 1994
621.385 dc20 94-29054
CIP
Preface
What is "digital telephony"? To the authors, the term digital telephony denotes
the technology used to provide a completely digital telecommunication system
from end-to-end. This implies the use of digital technology from one end instru
ment through transmission facilities and switching centers to another end instru
ment. Digital telephony has become possible only because of the recent and on
going surge of semiconductor developments, allowing microminiaturization and
high reliability along with reduced costs.
This book deals with both the future and the present. Thus, the first chapter is
entitled, "A Network in Transition." As baselines, Chapters 2 and 11 provide the
reader with the present status of teler-hone technology in terms of voice digiti
zation as well as switching principles.
The book is an outgrowth of the authors' consulting and teaching experience
in the field since the early 1980s. The book has been written to provide both the
engineering student and the practicing engineer a working knowledge of the prin
ciples of present and future telecommunication systems based upon the use of the
public switched network. Problems or discussion questions have been included
at the ends of the chapters to facilitate the book's use as a senior-level or first
year graduate-level course text.
Numerous clients and associates of the authors as well as hundreds of others
have provided useful information and examples for the text, and the authors wish
to thank all those who have so contributed either directly or indirectly.
The first chapter, which is a joint effort of both authors, provides an overview
of the field. Chapters 2-4 deal with the subject of speech digitization, while
Chapters 5 and 6 are devoted to the use of digital technology in the telephone
network and for transmission in general. Chapter 7 deals with the new and rapidly
growing field of digital cellular radio. Chapters 8-10 treat three principal facility
iii
iv Preface
types for digital transmission: microwave radio, communication satellite systems,
and fiber optics.
Chapter 11 deals with generic architectural considerations for digital switching
systems, and Chapter 12 describes the architecture of some digital switching
systems that are currently operating in the North American network. Network
structure, transmission, and signaling of the North American network, both local
and long distance, as well as digital network synchronization, are covered in
Chapter 13, as the all-digital network continues to evolve. As the network has
become more and more digital, initial implementation of the integrated services
digital network (ISDN) on a North American basis has become practicable, and
is the subject of Chapter 14, along with the beginnings of broadband networking.
Chapter 15 is a new chapter concerning the efforts to extend digital telephony to
the "last mile," the local loop to subscribers' premises.
Because of the rapidly changing nature of the subjects covered in this volume,
the authors invite reader comments, questions, and suggestions for future editions.
The authors acknowledge the useful comments and suggestions provided by
the reviewers of the text. A special note of thanks goes to Dr. Stuart Yuill and
his students at Johns Hopkins University for their careful review of a prepubli
cation copy of the text, and for their many useful comments and suggestions.
Thanks go to Mr. Eric Schimmel of the TIA, Mr. James Mullen of Hughes Net
work Systems, Inc., Dr. Andrew Viterbi and Dr. Mark Epstein of QUALCOMM,
Inc., Dr. Donald Schilling of Interdigital Communications Corporation, Mr. Keith
Radousky of Bell South Cellular Corporation, and to Mr. Robert Dixon of Om
nipoint Communications, Inc., all of whom were very helpful in providing es
sential information in the development of Chapter 7. Thanks also go to Jerry
Klein of AT&T Bell Laboratories, Pat Maluchnik of AT&T Network Systems,
Wanda Baldwin and Kevin Molloy of Northern Telecom, Inc., and Jayne Scott
of Siemens Stromberg-Carlson for their kindness in making available product
information for Chapter 12. Kathleen Roberts of the National Institute of Stan
dards and Technology (NIST) was most helpful in connection with information
concerning the inauguration of nationwide ISDN in the United States, and Dr.
Mark Karol of AT&T Bell Laboratories provided information on AT M switching,
both covered in Chapter 14.
BERNHARD E. KEISER
EUGENE STRANGE
Vienna, Virginia
Contents
1 A NETWORK IN TRANSITION 1
1.1 Introduction
1.2 Major Historical Milestones 2
1.2.1 Modulation of Direct Current 3
1.2.2 Vacuum-Tube Technology 4
1.2.3 Semiconductor Technology 5
1.2.4 Optical Transmission Technology 6
1.2.5 Wireless Technology 6
1.3 A Futuristic Look 7
1.4 Organization of the Text 8
2 SPEECH DIGITIZATION FUNDAMENTALS 10
2.1 Introduction 10
2.2 Speech Coding Approaches 11
2.3 Sampling 13
2.4 Quantization 15
2.5 Effect of Digitization on Bandwidth 17
2.6 Speech Digitizer Performance Definitions 18
2.7 Speech-Coding Advantages 20
Problems 21
References 22
3 WAVEFORM CODING 23
3.1 Introduction 23
3.2 Basic PCM Encoding 25
3.3 Compression and Nonuniform Quantization 31
3.4 PCM Performance 35
3.5 Special PCM Techniques 39
v
vi Contents
3.5.1 Coarsely Quantized PCM 39
3.5.2 Nearly Instantaneous Companding 42
3.6 Differential PCM 44
3.6.1 Basic DPCM Concepts 46
3.6.2 Adaptive DPCM (ADPCM) 49
3.7 Delta Coding 52
3.7.1 Linear Delta Coding 52
3.7.2 Adaptive Delta Coding 58
3.7.2.1 Continuously Variable-Slope Delta (CVSD) 60
3.7.2.2 Digitally Controlled Delta Coding 62
3.8 Subband Coding (SBC) 62
3.9 Adaptive Transform Coding (ATC) 68
3.10 Harmonic Scaling 70
3.11 Vector Techniques 70
3.12 Performance of Efficient Waveform Coding Techniques 73
Problems 81
References 81
4 PARAMETRIC AND HYBRID CODING 84
4.1 Introduction 84
4.2 Principles of Low-Bit-Rate Speech Encoding 86
4.3 Vocoders 86
4.3.1 Linear Predictive Coding (LPC) 87
4.3.2 Other Vocoders 90
4.3.3 Effect of Model on Speech Quality 93
4.4 Hybrid (Waveform-Parametric) Techniques 93
4.5 Adaptive Predictive Coding (APC) 94
4.6 Multipulse LPC 95
4.7 Residual-Excited Linear Prediction Vocoder (RELP) 95
4.8 Code-Excited Linear Prediction (CELP) 98
4.9 Vector-Sum-Excited Linear Prediction (VSELP) 104
4.10 Regular Pulse Excitation with Long-Term Prediction (RPE-LTP) 106
4.11 Voice Digitizer Comparisons 108
Problems 108
References 109
5 DIGITAL TECHNIQUES IN THE TELEPHONE NETWORK 111
5.1 Introduction 111
5.2 Synchronization 112
5.2.1 Frame Synchronization 112
5.2.2 Timing 115
5.2.3 Timing Recovery 116
5.3 Time-Di vision Multiplexing 117
5.3.1 T-Carrier Systems 119
5.3.2 The Digital Hierarchy 120
Contents vii
5.3.3 Muldems 122
5.3.4 Transmultiplexers 125
5.4 Scramblers 128
5.5 Channel Coders 130
5.6 Echo Cancelers 135
5.7 Digital Speech Interpolation 137
5.8 Digital Repeaters 139
5.9 Digitization of the Loop Plant 142
5.9.1 Transmission Modes 143
5.9.1.1 Wired Systems 143
5.9.1.2 Pair-Gain Systems 145
5.9.1.3 Discrete Multitone (DMT) Systems 145
5.9.1.4 Radio Systems 146
5.9.2 Line Codes 147
5.9.3 Digital End Instruments 147
5.10 Monitoring and Maintenance 149
5.11 Speech Recognition 150
5.11.1 Speech Production 150
5.11.2 Speech-Recognition Systems 151
5.11.3 Speech-Recognition Techniques 152
5.11.4 Voice-Input Systems 153
5.12 Voice Response 153
Problems 156
References 156
6 DIGITAL TRANSMISSION 159
6.1 Introduction 159
6.1.1 Performance Objectives 159
6.1.2 Signal Impairments in Transmission 159
6.1.3 The Nyquist Theorem 161
6.1.4 The Shannon Limit 166
6.2 Digital Modulation Techniques 167
6.2.1 Phase-Shift Keying 170
6.2.1.1 Binary Phase-Shift Keying (BPSK) 173
6.2.1.2 Quaternary Phase-Shift Keying (QPSK) 174
6.2.1.3 Eight-Phase Shift Keying (8-PSK) 175
6.2.1.4 Sixteen~Phase Shift Keying (16-PSK) 177
6.2.2 Amplitude-Shift Keying and Quadrature Amplitude Modulation 177
6.2.3 Amplitude-Phase Keying 180
6.2.4 Frequency-Shift Keying 181
6.2.5 Correlative Techniques 184
6.2.6 Comparison of Modulation Techniques 188
6.2.6.1 Bandwidth Efficiency 189
6.2.6.2 Modulation Technique Performance 191
6.3 Error Control 191
viii Contents
6.3.1 Error Detection 195
6.3.2 Error Correction 195
6.3.3 Block and Convolutional Codes 196
6.3.4 Bose-Chaudhuri-Hocquenghem (BCH) Code 197
6.4 Multiple Access 197
6.4.1 Frequency-Division Multiple Access (FDMA) 197
6.4.2 Time-Division Multiple Access (TDMA) 198
6.4.3 Code-Division Multiple Access (CDMA) 198
6.5 Packet Transmission 199
6.5.1 Packet Voice 200
6.5.2 Statistical Multiplexing 202
6.5.3 Fast Packet Switching 204
6.5.3.1 Frame Relay 204
6.5.3.2 Cell Relay 204
6.6 Retrofit 205
Problems 208
References 208
7 DIGITAL CELLULAR RADIO 211
7.1 Introduction 211
7.2 Radio-Wave Propagation 213
7.2.1 The Mobile Antenna 213
7.2.2 Signal Fading Characteristics 214
7.2.3 Effect of Fading on Digital Transmission 218
7.2.4 Effect of Propagation on System Design 220
7.2.5 Frequency Reuse 224
7.2.6 Channel Assignments 227
7.3 Cellular System Operation 229
7.3.1 Call Setup 230
7.3.1.1 Fixed-Station Originated Call 232
7.3.1.2 Subscriber-Set Originated Call 232
7.3.1.3 Disconnect 233
7.3.2 Hand-off 233
7.3.3 Roaming 234
7.4 Multiple Access Concepts 235
7.4.1 Time-Division Multiple Access (TDMA) 237
7.4.1.1 Basic TDMA 237
7.4.1.2 Extended TDMA (E-TDMA) 239
7.4.2 Code-Division Multiple Access (CDMA) 245
7.4.2.1 QUALCOMM CDMA 246
7.4.2.2 Broadband CMDA 251
7.4.3 Hybrid Digital System 253
7.4.4 Frequency-Hopping Multiple Access (FHMA) 253
7.5 Data Transmission 253
7.6 Spectrum Efficiency 254
Contents ix
7.7 Summary of Digital Cellular System Characteristics 256
7.7.1 North American Digital Cellular System (TDMA) 256
7.7.2 Extended TDMA (E-TDMA) 257
7.7.3 Japanese Digital Cellular System 257
7.7.4 The Global System Mobile (GSM) 257
7.7.5 Code-Division Multiple Access (CDMA) 258
7.8 The Microcellular Environment 258
7.8.1 The Propagation Environment 259
7.8.2 Personal Communication Networks (PCNs) 260
7.8.3 Indoor Radio Systems 260
7.8.4 System Examples 262
7.9 The Wireless Local Loop 263
7.10 The PeS Interface to the PSTN 266
Problems 267
References 267
8 MICROWAVE TRANSMISSION 270
8.1 Introduction 270
8.2 Characteristics of Microwave Propagation 271
8.2.1 Spreading Loss and Absorption 271
8.2.2 Fading 273
8.2.3 Polarization 275
8.3 Microwave System Engineering 276
8.3.1 Frequency Allocations 276
8.3.2 Link Budget 279
8.3.3 Repeater Siting 280
8.3.4 Diversity 282
8.3.5 Reliability and Availability 282
8.4 Characteristics of Microwave Equipment 284
8.4.1 Amplifiers 284
8.4.1.1 Power Amplifiers 284
8.4.1.2 Small Signal Amplifiers 284
8.4.2 Antennas 285
8.4.3 System Interface Arrangements 289
8.5 Digital Microwave Radio Systems 289
8.5.1 Systems for Intercity and Long-Haul Applications 290
8.5.2 Metropolitan-Area Systems 294
8.5.2.1 Digital Termination Systems 294
8.5.2.2 Private Systems 294
8.5.2.3 Common-Carrier Systems 295
8.5.2.4 SONET-Compatible Radio Systems 295
Problems 296
References 296
x Contents
9 SATELLITE TRANSMISSION 298
9.1 Introduction 298
9.2 Characteristics of Satellite Propagation 299
9.2.1 The Satellite Orbit 299
9.2.2 Time Delay on Satellite Paths 300
9.2.3 Atmospheric Attenuation 300
9.2.4 Rain Depolarization 301
9.3 Satellite System Design 302
9.3.1 Frequency Allocations and Usage 302
9.3.2 Link Budgets 305
9.3.3 Earth-Station Siting 307
9.3.4 Multiple Access 309
9.3.4.1 Frequency-Division Multiple Access 309
9.3.4.2 Time-Division Multiple Access 311
9.3.4.3 Code-Division Multiple Access 312
9.3.5 Multiplexing 313
9.3.6 Demand Assignment 313
9.3.7 Echo Cancellation 314
9.4 Characteristics of Satellite System Equipment 314
9.4.1 Space Segment 316
9.4.1.1 Transponders 316
9.4.1.2 Control Subsystem 321
9.4.2 The Earth Station 321
9.5 Major Operational Communication Satellite Systems 324
9.6 Satellite Systems for Direct Service to the User 325
9.7 Future Trends in Communication Satellite Systems 327
Problems 330
References 331
10 FIBER·OPTIC TRANSMISSION 333
10.1 Introduction 333
10.2 Fiber Transmission Characteristics 334
10.2.1 Attenuation 335
10.2.2 Dispersion 337
10.2.3 Soliton Transmission 337
10.3 Fiber Types 337
10.3.1 Multimode Fibers 340
10.3.2 Single-Mode Fibers 341
10.3.3 Graded-Index Fibers 341
10.4 Optical Sources 342
10.4.1 Types 342
10.4.2 Coherent Sources 343
10.4.3 Modulation 344
10.4.4 Coupling of Sources to Fibers 348
10.5 Photodetectors 348
10.5.1 Noncoherent Detectors 348