DIGITAL COMMUNICATION. Third Edition

Transcription

1 DIGITAL COMMUNICATION Third Edition

2 DIGITAL COMMUNICATION Third Edition John R. Barry Georgia Institute of Technology Edward A. Lee University of California at Berkeley David G. Messerschmitt University of California at Berkeley Volume I SPRINGER SCIENCE+BUSINESS MEDIA, LLC

3 Library of Congress Cataloging-in-Publication Data Barry, John R., Digital Communication/ John R. Barry, Edward A. Lee, and David G. Messerschmitt. -3 rd ed. p.cm. Rev. ed. of: Digital Communication / Edward A. Lee, David G. Messerschmitt. 2 nd ed. c Includes bibliographical references and index. ISBN ISBN (ebook) DOI / Digital Communications. I. Lee, Edward A., II. Messerschmitt, David G. III. Lee, Edward A., Digital Communication. IV. Title. TK L dc Copyright 2004 by Springer Science+Business Media New York Originally published by Kluwer Academic Publishers in 2004 Softcover reprint of the hardcover 3rd edition 2004 All rights reserved. No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without the written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Permission for books published in Europe: perniissions@wkap.nl Permissions for books published in the United States of America: permissions@wkap.com Printed on acid-free paper.

4 To Annis, Reid, and Neil Rhonda, Helen, and Katalina Dody and Laura

5 CONTENTS Preface Changes from the Second Edition Notes to an Instructor xiii xv xvii 1. Introduction Applications of Digital Communication Digital Networks Digital vs. Analog Communications Plan of the Book Further Reading 7 2. Deterministic Signal Processing Signals LTI Systems and Fourier Transforms The Nyquist Sampling Theorem Downconversion and Complex Envelopes Z Transforms and Rational Transfer Functions Signals as Vectors 33 2-A Properties of the Fourier Transform 44 2-B Spectral Factorization 47

6 viii 3. Stochastic Signal Processing Random Variables Random Processes Markov Chains The Poisson Process and Queueing Further Reading 99 3-A Power Spectrum of A Cyclostationary Process B Power Spectrum of A Markov Chain C Derivation of a Poisson Process D Moment Generating Function of Shot Noise Limits of Communication Just Enough Information About Entropy Capacity of Discrete-Time Channels Further Reading A Asymptotic Equipartition Theorem Pulse-Amplitude Modulation Baseband PAM Passband PAM The One-Shot Minimum-Distance Receiver Minimum-Distance Sequence Detection Performance Analysis in AWGN Further Reading Advanced Modulation M-ary Modulation Probability of Error Orthogonal Modulation Orthogonal Pulse-Amplitude Modulation (OPAM) Modulation with Memory Bandwidth and Signal Dimensionality Capacity and Modulation Further Reading A The Generalized Nyquist Criterion 274

7 IX 7. Probabilistic Detection Detection of a Single Real-Valued Symbol Detection of a Signal Vector Known Signals in Gaussian Noise ML Sequence Detection with the Viterbi Algorithm A Posteriori Probability Detection with BCJR Symbol-Error Probability for MLSD Incoherent Detection Shot Noise Signal with Known Intensity Further Reading A Karhunen-Loeve Expansion B Bit-Error Probability for Sequence Detectors C BCJR Forward/Backward Recursions Equalization Optimal Zero-Forcing Equalization Generalized Equalization Methods Fractionally Spaced Equalizer Transversal Filter Equalizers lsi and Channel Capacity Further Reading A DFE Error Propagation Adaptive Equalization Constrained-Complexity Equalizers Adaptive Linear Equalizer Adaptive DFE Fractionally Spaced Equalizer Passband Equalization Further Reading A SG Algorithm Error Vector Norm MIMO Communications Basics of MIMO Systems The Gaussian MIMO Channel Memoryless MIMO Channels MIMO Detection with Channel Memory Further Reading A Proof of Separability Result (10.45) 530

8 x 11. Fading and Diversity Types of Diversity Receiver Diversity Performance Analysis for Rayleigh Fading The Diversity-Interference Trade-Off Transmit Diversity Layered Space-Time Modems 11-A Proof of Conservation Theorem 11-B Bound on Pairwise Error Probability 12. Error Control The Capacity Penalty of Binary Coding Binary Linear Block Codes Convolutional Codes Low-Density Parity-Check Codes Turbo Codes Historical Notes and Further Reading 12-A Linear Codes 12-B Maximal-Length Feedback Shift Registers 12-C Path Enumerators 12-D Derivation of the Tanh Rule 13. Signal-Space Coding Multidimensional Signal Constellations Trellis Codes Coset Codes Signal-Space Coding and lsi Further Reading 14. Phase-Locked Loops Ideal Continuous-Time PLL Discrete-Time PLLs Phase Detectors Variations on a Theme: VCOs Further Reading

9 Xl 15. Carrier Recovery Decision-Directed Carrier Recovery Power of N Carrier Recovery Further Reading 16. Timing Recovery Timing Recovery Performance Spectral-Line Methods MMSE Timing Recovery and Approximations Baud-Rate Timing Recovery Accumulation of Timing Jitter Further Reading 16-A The Poisson Sum Formula 16-B Discrete-Time Derivative 17. Multiple Access Alternatives Medium Topology for Multiple Access Multiple Access by Time Division Multiple Access by Frequency Division Multiple Access by Code Division The Cellular Concept Exercise Solutions Index

10 Preface This book concerns digital communication. Specifically, we treat the transport of bit streams from one geographical location to another over various physical media, such as wire pairs, coaxial cable, optical fiber, and radio. We also treat multiple-access channels, where there are potentially multiple transmitters and receivers sharing a common medium. Ten years have elapsed since the Second Edition, and there have been remarkable advances in wireless communication, including cellular telephony and wireless local-area networks. This Third Edition expands treatment of communication theories underlying wireless, and especially advanced techniques involving multiple antennas, which tum the traditional single-input single-output channel into a multiple-input multiple-output (MIMO) channel. This is more than a trivial advance, as it stimulates many advanced techniques such as adaptive antennas and coding techniques that take advantage of space as well as time. This is reflected in the addition of two new chapters, one on the theory of MIMO channels, and the other on diversity techniques for mitigating fading. The field of error-control coding has similarly undergone tremendous changes in the past decade, brought on by the invention of turbo codes in 1993 and the subsequent rediscovery of Gallager's low-density parity-check codes. Our treatment of error-control coding has been rewritten to reflect the current state of the art. Other materials have been reorganized and reworked, and three chapters from the previous edition have been moved to the book's Web site to make room. For this third edition we have added a third author, John Barry, who carried the major burden of these revisions. The general approach of this book is to extract the common principles underlying a range of media and applications and present them in a unified framework. It is relevant to the design of a variety of systems, including voice and video digital cellular telephone, digital CATV distribution, wireless LANs, digital subscriber loop, metallic ethernet, voiceband data modems, and satellite communication systems. This book is intended for designers and would-be designers of digital communication systems. To limit the length we have been selective in topics covered and in the depth of coverage. For example, the coverage of advanced information, coding, and detection theory is limited to those aspects directly relevant to the design of digital communication systems. This

11 xiv emphasis on topics important to designers results in more detailed treatment of some topics than is traditional in academic textbooks, for example in our coverage of synchronization (timing and carrier recovery). This book is suitable as a first-year graduate textbook, and should also be of interest to many industry professionals. We have attempted to make the book attractive to both audiences through the inclusion of many practical examples and a practical flavor in the choice of topics. In addition, we have increased the readability by relegating many of the more detailed derivations to appendices and exercise solutions, both of which are included in the book. The book has a Web site at where the reader may find the chapters "Physical Media and Channels," "Spectrum Control," and "Echo Cancellation" from the Second Edition, other supplementary materials, useful links, a problem solutions manual, and errata. For this third edition, we owe a debt of gratitude to Abdallah Said AI-Ahmari, Anuj Batra, Richard T. Causey, Elizabeth Chesnutt, Arumugam Kannan, Piya Kovintavewat, Renato da Rocha Lopes, Aravind R. Nayak, Faith Nilo, Joon Hyun Sung, Badri Varadarajan, Deric Waters, and to several anonymous reviewers. In addition we gratefully acknowledge the many people who helped shape the first two editions. Any remaining errors are the full responsibility of the authors. We hope the result is a readable and useful book, and always appreciate comments and suggestions from the readers. John R. Barry Edward A. Lee David G. Messerschmitt Atlanta, Georgia Berkeley, California June 10, 2003

12 Changes from the Second Edition The Third Edition differs from the Second Edition in three significant ways. First, chapters 6 through 9 from the Second Edition have been reorganized and streamlined to highlight pulse-amplitude modulation, becoming the new chapters 5 through 7. Second, new material on recent advances in wireless communications, error-control coding, and multiuser communications has been added. As a result, two new chapters have been added. Finally, the three chapters "Physical Media and Channels," "Spectrum Control," and "Echo Cancellation" from the Second Edition have been moved to the book Web site. Here is a chapter-by-chapter summary of the major changes for this Third Edition: Chapter 2. The up converter, downconverter, and complex envelope are defined in mathematical terms for later use. More details of linear waveform spaces, including orthonormal bases and the Gram-Schmidt procedure, are added. Chapter 5. This chapter focuses exclusively on pulse-amplitude modulation (PAM), both passband and baseband. It consolidates material that was previously spread across four different chapters. The new organization retains the intuitive flow that characterized the Second Edition, with initial emphasis on the deterministic features of PAM systems. The minimum-distance receiver is proposed, first for an isolated pulse and then for dispersive channels with intersymbol interference, which leads to such concepts as the correlator, matched filter, whitened-matched filter and the Viterbi algorithm. The statistics of the noise do not enter into the picture until the very end, where we analyze the performance of various PAM techniques with minimum-distance detection in the presence of white Gaussian noise. Separating PAM like this offers two key advantages. First, PAM and its derivatives (like multicarrier modulation) are a preferred choice for many emerging applications, making PAM a worthy topic of study in its own right. A practicing engineer may wish to study PAM only, and the new organization makes this easy to do. Second, focusing on PAM allows us to

13 xvi introduce important concepts (such as minimum-distance detection and power-bandwidth trade-offs) in a highly focused and motivated setting. In a sense, we use PAM as a case study, which facilitates the generalization to arbitrary M-ary modulation schemes that follows. Chapter 6. This chapter moves beyond PAM to examine advanced modulation techniques such as orthogonal modulation and orthogonal pulse-amplitude modulation, which includes code-division multiple access and multicarrier modulation (such as OFDM) as special cases. Also covered are advanced topics such as modulation with memory, the relationship between bandwidth and dimensionality, and the normalized SNR as a means for comparing modulation to Shannon capacity. Chapter 7. This chapter adopts a probabilistic approach to the detection problem, thus expanding our scope beyond white-gaussian noise. The Viterbi algorithm is formulated in probabilistic terms, and it is related to the forward-backward (or BCJR) algorithm for a posteriori-probability detection, which plays a key role in turbo decoding. Chapter 10. This new chapter examines the fundamentals of multiple-input multipleoutput communications, with particular emphasis on the detection problem, also known as the multiuser detection problem. Chapter 11. This new chapter describes diversity techniques for mitigating multipath fading, which exploit antenna arrays at either the transmitter or the receiver (or both). We examine beamforming and combining techniques as well as space-time codes and spatial multiplexing. Chapter 12. New material on low-density parity-check codes has been added, including Tanner graphs, message-passing decoding, and density evolution. We also describe parallelconcatenated and serial-concatenated turbo codes and turbo-decoding algorithms, with repeataccumulate codes and turbo equalization treated as special cases.

14 Notes to an Instructor This book can be used as a textbook for advanced undergraduates, or for a first course in digital communication for graduate students. We presume a working knowledge oftransfonns, linear systems, and random processes, and review these topics in chapters 2 and 3 at a depth suitable only for establishing notation. This treatment also serves to delimit the background assumed in the remainder of the book, or with more advanced students can be omitted or made optional. We include a more detailed treatment of basic topics important to digital communication but which may not be familiar to a first-year graduate student, including signal space (chapter 2), Markov chains and their analysis (chapter 3), Poisson processes and shot noise (chapter 3), the basic boundaries of communication from infonnation theory (chapter 4), and maximum-likelihood detection and the Viterbi algorithm (chapter 7). These treatments are self-contained and assume only the basic background mentioned earlier. These basic topics can be covered at the beginning of the course, or delayed until the first time they are used. Our own preference is the latter, since the immediate application of the techniques serves as useful reinforcement. The core of book is the treatment modulation, detection and equalization (chapters 5 through 9), MIMO channels (chapters 10 and 11), coding (chapters 12 and 13), and synchronization (chapters 14 through 16). These topics are covered in considerable depth. After completing a course based on this book, students should be highly motivated to take advanced courses in infonnation theory, algebraic coding, detection and estimation theory, and communication networks, and will have a prior appreciation of the utility of these topics. There is sufficient material for two semesters, although it can easily be used for a singlesemester course by selectively covering topics. At Georgia Tech we use this book for a onesemester graduate course that has as prerequisites undergraduate courses in systems and transfonns and probability and random processes. We do not presume any prior exposure to signal space, Markov chains, or the Poisson process. In this course we rely on the students to review Chapters 1 through 4, and we cover Chapters 5 through 8 and Chapter 10 and 11 in lecture. Chapters 9, 12 and 13 are skipped because adaptive filtering and error-control coding techniques are covered in other courses.