Description:

This page intentionally left blank Fundamentals of Digital Communication This textbook presents the fundamental concepts underlying the design of modern digital communication systems which include wireline, wireless and storage systems that pervade our everyday lives. Using a highly accessible lecture style exposition this rigorous textbook first establishes a firm grounding in classical concepts of modulation and demodulation and then builds on these to introduce advanced concepts in synchronization noncoherent communication channel equalization information theory channel coding and wireless communication. This up-to-date textbook covers turbo and LDPC codes in sufficient detail and clarity to enable hands-on implementation and performance evaluation as well as “just enough” information theory to enable computation of performance benchmarks to compare them against. Other unique features include the use of complex baseband representation as a unifying framework for transceiver design and implementation; wireless link design for a number of modulation formats including space–time communication; geometric insights into noncoherent communication; and equalization. The presentation is self-contained and the topics are selected so as to bring the reader to the cutting edge of digital communications research and development. Numerous examples are used to illustrate key principles with a view to allowing the reader to perform detailed computations and simulations based on the ideas presented in the text. With homework problems and numerous examples for each chapter this textbook is suitable for advanced undergraduate and graduate students of electrical and computer engineering and can be used as the basis for a one or two semester course in digital communication. It will also be a valuable resource for practitioners in the communications industry. Additional resources for this title including instructor-only solutions are available online at www.cambridge.org 9780521874144 Upamanyu Madhow is Professor of Electrical and Computer Engineering at the University of California Santa Barbara. He received his Ph.D. in Electrical Engineering from the University of Illinois Urbana-Champaign in 1990 where he later served on the faculty. A Fellow of the IEEE he worked for several years at Telcordia before moving to academia. Fundamentals of Digital Communication Upamanyu Madhow University of California Santa Barbara CAMBRIDGE UNIVERSITY PRESS Cambridge New York Melbourne Madrid Cape Town Singapore São Paulo Cambridge University Press The Edinburgh Building Cambridge CB2 8RU UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org 9780521874144 © Cambridge University Press 2008 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements no reproduction of any part may take place without the written permission of Cambridge University Press. First published in print format 2008 ISBN-13 978-0-511-38606-0 ISBN-13 978-0-521-87414-4 eBook (EBL) hardback Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. To my family Contents Preface Acknowledgements 1 Introduction 1.1 Components of a digital communication system 1.2 Text outline 1.3 Further reading 2 Modulation 2.1 Preliminaries 2.2 Complex baseband representation 2.3 Spectral description of random processes 2.3.1 Complex envelope for passband random processes 2.4 Modulation degrees of freedom 2.5 Linear modulation 2.5.1 Examples of linear modulation 2.5.2 Spectral occupancy of linearly modulated signals 2.5.3 The Nyquist criterion: relating bandwidth to symbol rate 2.5.4 Linear modulation as a building block 2.6 Orthogonal and biorthogonal modulation 2.7 Differential modulation 2.8 Further reading 2.9 Problems 3 Demodulation 3.1 Gaussian basics 3.2 Hypothesis testing basics vii page xiii xvi 1 2 5 6 7 8 18 31 40 41 43 44 46 49 54 55 57 60 60 60 62 64 66 74 75 88 viii Contents 3.3 Signal space concepts 94 3.4 Optimal reception in AWGN 102 3.4.1 Geometry of the ML decision rule 106 3.4.2 Soft decisions 107 3.5 Performance analysis of ML reception 109 3.5.1 Performance with binary signaling 110 3.5.2 Performance with M-ary signaling 114 3.6 Bit-level demodulation 127 3.6.1 Bit-level soft decisions 131 3.7 Elements of link budget analysis 133 3.8 Further reading 136 3.9 Problems 136 3.9.1 Gaussian basics 136 3.9.2 Hypothesis testing basics 138 3.9.3 Receiver design and performance analysis for the AWGN channel 140 3.9.4 Link budget analysis 149 3.9.5 Some mathematical derivations 150 4 Synchronization and noncoherent communication 153 4.1 Receiver design requirements 155 4.2 Parameter estimation basics 159 4.2.1 Likelihood function of a signal in AWGN 162 4.3 Parameter estimation for synchronization 165 4.4 Noncoherent communication 170 4.4.1 Composite hypothesis testing 171 4.4.2 Optimal noncoherent demodulation 172 4.4.3 Differential modulation and demodulation 173 4.5 Performance of noncoherent communication 175 4.5.1 Proper complex Gaussianity 176 4.5.2 Performance of binary noncoherent communication 181 4.5.3 Performance of M-ary noncoherent orthogonal signaling 185 4.5.4 Performance of DPSK 187 4.5.5 Block noncoherent demodulation 188 4.6 Further reading 189 4.7 Problems 190 5 Channel equalization 199 5.1 The channel model 200 5.2 Receiver front end 201 5.3 Eye diagrams 203 5.4 Maximum likelihood sequence estimation 204 5.4.1 Alternative MLSE formulation 212 5.5 Geometric model for suboptimal equalizer design 213 5.6 Linear equalization 216 ix Contents 5.6.1 Adaptive implementations 223 5.6.2 Performance analysis 226 5.7 Decision feedback equalization 228 5.7.1 Performance analysis 230 5.8 Performance analysis of MLSE 231 5.8.1 Union bound 232 5.8.2 Transfer function bound 237 5.9 Numerical comparison of equalization techniques 240 5.10 Further reading 242 5.11 Problems 243 5.11.1 MLSE 243 6 Information-theoretic limits and their computation 252 6.1 Capacity of AWGN channel: modeling and geometry 253 6.1.1 From continuous to discrete time 256 6.1.2 Capacity of the discrete-time AWGN channel 257 6.1.3 From discrete to continuous time 259 Ключевые слова: binary, discrete-time, ax, db db, noise, snr, probability, power, receiver, baseband, awgn channel, mv, ej, uc vc, mu, bandwidth, phase, channel, term, dt, nt, cyclic prefix, noncoherent, error probability, bit, filter, es ij, algorithm, sample, independent, steepest ascent, csk, theory, digital, perpendicular bisector, output, qk qk, converter, compute, pk, gaussian, lpath, sk, gc fn, real, nc ns, matrix, energy, kt s, check, mk, performance, pe, turbo, detailed investigation, variable, xn, random, model, signaling, mt, estimate, random variable, si sj, uk, waveform, s t, asymptotic efficiency, decoding, case, pto, yi sk, h sa, code, received, perfectly canceled, error, density, zc zs, yk, bound, belief propagation, yk sk, decision-directed mode, frequency, capacity, discus, based, communication, input, constellation, sjl, rc, ltc, suppose, orthogonal, condition, sc t, pe bi, sequence, xk, process, signal, vice versa, kt, sc, eb, space, random process, grammschmidt orthogonalization, transmitted, log, passband, result, form, fc, ek, l dl, wireless, function, awgn, db, modern transceivers, psd, cn, component, assume, distribution, majority logic, mx, power-delay profile, optimal, tone spacing, linear, decision, abx, gaussian random, re b, yk ck, complex, cfhfuj cfhfwn, rate, coding, gain, pi, es, nc, time, number, demodulation, worth mentioning, yk vk, spectral efficiency, average, e eb, nda mode, exit chart, doe, yp sp, pulse, decoder, node, set, user, large, onoff keying, plot, fn, problem, observation, ha, codeword, discrete, si si, uc, rs, gc, qpsk, isi, chapter, received signal, pu qu, preceding, bpsk, xc xs, s f, vector, sb sb, complex baseband, note, si, modulation, design, ns, ut, p t, rule, denote, mf, yk uk, vp, trellis, interval, xi, symbol