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Introduction to Analogand Digital Communications

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Introduction to Analogand Digital CommunicationsSecond EditionSimon HaykinMcMaster University, Hamilton, Ontario, CanadaMichael MoherSpace-Time DSP, Ottawa, Ontario, CanadaJOHN WILEY & SONS, INC.

ASSOCIATE PUBLISHER Dan SayreSENIOR ACQUISITIONS EDITOR AND PROJECT MANAGERPROJECT EDITOR Gladys SotoMARKETING MANAGER Phyllis Diaz CerysEDITORIAL ASSISTANT Dana KellogSENIOR PRODUCTION EDITOR Lisa WojcikMEDIA EDITOR Stefanie LiebmanDESIGNER Hope MillerSENIOR ILLUSTRATION EDITOR Sigmund MalinowskiCOVER IMAGE Photodisc/Getty ImagesCatherine ShultzThis book was set in Quark by Prepare Inc. and printed and bound by Hamilton Printing. The cover was printedby Phoenix Color Corp.This book is printed on acid free paper. Copyright 2007 John Wiley & Sons, Inc. All rights reserved. No part of this publication may be reproduced,stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying,recording, scanning, or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of theappropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923,(978)750-8400, fax (978)646-8600, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, (201)7486011, fax (201)748-6008, or online at http://www.wiley.com/go/permissions.To order books or for customer service please, call 1-800-CALL WILEY (225-5945).ISBN-13 978-0-471-43222-7ISBN-10 0-471-43222-9Printed in the United States of America10 9 8 7 6 5 4 3 2 1

To the 20th Century pioneers in communications who,through their mathematical theories and ingenious devices,have changed our planet into a global village

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PREFACEAn introductory course on analog and digital communications is fundamental to the undergraduate program in electrical engineering. This course is usually offered at the junior level.Typically, it is assumed that the student has a background in calculus, electronics, signalsand systems, and possibly probability theory.Bearing in mind the introductory nature of this course, a textbook recommended forthe course must be easy to read, accurate, and contain an abundance of insightful examples, problems, and computer experiments. These objectives of the book are needed toexpedite learning the fundamentals of communication systems at an introductory level andin an effective manner. This book has been written with all of these objectives in mind.Given the mathematical nature of communication theory, it is rather easy for thereader to lose sight of the practical side of communication systems. Throughout the book,we have made a special effort not to fall into this trap. We have done this by movingthrough the treatment of the subject in an orderly manner, always trying to keep the mathematical treatment at an easy-to-grasp level and also pointing out practical relevance of thetheory wherever it is appropriate to do so.Structural Philosophy of the BookTo facilitate and reinforce learning, the layout and format of the book have beenstructured to do the following: Provide motivation to read the book and learn from it. Emphasize basic concepts from a “systems” perspective and do so in an orderly manner. Wherever appropriate, include examples and computer experiments in each chapter to illustrate application of the pertinent theory. Provide drill problems following the discussion of fundamental concepts to help the userof the book verify and master the concepts under discussion. Provide additional end-of-chapter problems, some of an advanced nature, to extend thetheory covered in the text.Organization of the book1. MotivationBefore getting deeply involved in the study of analog and digital communications, it is imperative that the user of the book be motivated to use the book and learnfrom it. To this end, Chapter 1 begins with a historical background of communication systems and important applications of the subject.2. Modulation Theory Digital communication has overtaken analog communications as thedominant form of communications. Although, indeed, these two forms of communicationswork in different ways, modulation theory is basic to them both. Moreover, it is easiest tounderstand this important subject by first covering its fundamental concepts applied to analog communications and then moving on to digital communications. Moreover, amplitudemodulation is simpler than angle modulation to present. One other highly relevant point isthe fact that to understand modulation theory, it is important that Fourier theory be mastered first. With these points in mind, Chapters 2 through 7 are organized as follows:ix

xAPPENDIX 1 POWER RATIOS AND DECIBEL Chapter 2 is devoted to reviewing the Fourier representation of signals and systems. Chapters 3 and 4 are devoted to analog communications, with Chapter 3 covering amplitude modulation and Chapter 4 covering angle modulation. Chapter 5 on pulse modulation covers the concepts pertaining to the transition from analog to digital communications. Chapters 6 and 7 are devoted to digital communications, with Chapter 6 covering baseband data transmission and Chapter 7 covering band-pass data transmission.3. Probability Theory and Signal Detection Just as Fourier analysis is fundamental to modulation theory, probability theory is fundamental to signal detection and receiver performanceevaluation in the presence of additive noise. Since probability theory is not critical to theunderstanding of modulation, we have purposely delayed the review of probability theory,random signals, and noise until Chapter 8. Then, with a good understanding of modulationtheory applied to analog and digital communications and relevant concepts of probabilitytheory and probabilistic models at hand, the stage is set to revisit analog and digital communication receivers, as summarized here: Chapter 9 discusses noise in analog communications. Chapter 10 discusses noise in digital communications. Because analog and digital communications operate in different ways, it is natural to see some fundamental differencesin treating the effects of noise in these two chapters.4. Noise The introductory study of analog and digital communications is completed in Chapter 11. This chapter illustrates the roles of modulation and noise in communication systemsby doing four things: First, the physical sources of noise, principally, thermal noise and shot noise, are described. Second, the metrics of noise figure and noise temperature are introduced. Third, how propagation affects the signal strength in satellite and terrestrial wireless communications is explained. Finally, we show how the signal strength and noise calculations may be combined to provide an estimate of the signal-to-noise ratio, the fundamental figure of merit for communication systems.5. Theme Examples In order to highlight important practical applications of communicationtheory, theme examples are included wherever appropriate. The examples are drawn fromthe worlds of both analog and digital communications.6. AppendicesTo provide back-up material for the text, eight appendices are included at theend of the book, which cover the following material in the order presented here: Power ratios and the decibel Fourier series Bessel functions The Q-function and its relationship to the error function Schwarz’s inequality Mathematical tables