Contemporary Communication Systems Using Matlab

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Contemporary Communication Systems Using Matlab

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Contemporary Communication Systems Using MATLAB® Third Edition John G Proakis Northeastern University Masoud Salehi Northeastern University Gerhard Bauch Universitiit der Bundeswehr Miinchen CENGAGE Learning· Australia• Brazil• japan• Korea• Mexico• Singapore• Spain• United Kingdom • United States Copyright 2011 Cengage Leaming All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience, Cengage Leaming reserves the right to remove additional content at any time if subsequent rights restrictions require it This is an electronic version of the print textbook Due to electronic rights restrictions, some third party content may be suppressed Editorial review has deemed that any suppressed content does not materially affect the overall learning experience The publisher reserves the right to remove content from this title at any time if subsequent rights restrictions require it For valuable information on pricing, previous editions, changes to current editions, and alternate formats, please visit www.cengage.com/highered to search by ISBN#, author, title, or keyword for materials in your areas of interest Copyright 2011 Cengage Lea.ming AJI Rights Reserved May not be copjed, scanned, or duplicated, in whole or in part Due to e)ectron.lc rights, some third party content may be suppressed from the eBook and/or eChapter(s) F.ditorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Leaming reserves the right to remove additional content at any time if subsequent rights restrictions require it CENGAGE Learning· Contemporary Communication Systems Using MATLAB®, Third Edition john G Proakis, Masoud Salehi, Gerhard Bauch Publisher, Global Engineering: Christopher M Shortt Acquisitions Editor: Swati Meherishi © 2013, 2004 Cengage Learning ALL RIGHTS RESERVED No part ofthis work covered by the copyright herein may be reproduced, transmitted, stored or used in any form or by any means graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the publisher Senior Developmental Editor: Hilda Gowans For product inf ormation and technology assistance, contact us at Editorial Assistant: Tanya Altieri Cengage Learning Customer & Sales Support, 1-800-354-9706 Team Assistant: Carly Rizzo For permission to use material from this text or product, Marketing Manager: Lauren Betsos submit all requests online at www.cengage.com/permissions Further permissions questions can be emailed to Media Editor: Chris Valentine permissionrequest@cengage.com Director, Content and Media Production: Sharon S Smith Production Manager: D jean Buttrom Library of Congress Control Number: 2011937462 Content Project Management: PreMediaGlobal ISBN-13: 978-0-495-08251-4 Production Service: PreMediaGlobal ISBN-10: 0-495-08251-1 Copyeditor: Patricia Daly Compositor: PreMediaGlobal Senior Art Director: Michelle Kunkler Internal Designer: PreMediaGlobal Cover Designer: Andrew Adams/4065042 Cengage Learning 200 First Stamford Place, Suite 400 Stamford, CT 06902 USA Canada Inc Cover Image:© teacept/Shutterstock Rights Acquisitions Specialist: john Hill Text and Image Permissions Researcher: Cengage Learning is a leading provider ofcustomized learning solutions with office locations around the globe, including Singapore, the United Kingdom, Australia, Mexico, Brazil, and japan Locate your local office at international.cengage.com/region Krist iina Paul Manufacturing Planner: Doug Wilke Cengage Learning products are represented in Canada by Nelson Education, Ltd For your course and learning solutions, visit www.cengage.com/engineering Purchase any of our products at your local college store or at our preferred online store www.cengagebrain.com MATLAB® and SIMULINK® are registered trademarks ofThe MathWorks, Apple Hill Drive, Natick, MA 01760 Printed in the United States of America 15 14 13 12 11 Copyright 2011 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in who1e or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materiaJJy affect the overall learning experience Cengage Leaming reserves the right to remove additional content at any time if subsequent rights restrictions require il PREFACE Many textbooks today treat the basic topics in analog and digital communication sys­ tems, including coding and decoding algorithms and modulation and demodulation techniques Most of these textbooks focus, by necessity, on the theory that underlies the design and performance analysis of the various building blocks, such as coders, decoders, modulators, and demodulators, that constitute the basic elements of a com­ munications system Relatively few of the textbooks, especially those written for un­ dergraduates, include applications that motivate students SCOPE OF THE BOOK The objective of this book is to serve as a companion or supplement to any of the comprehensive textbooks in communication systems The book provides a variety of exercises that may be solved on a computer (generally, a personal computer is suffi­ cient) using the popular student edition of MATLAB We intend the book to be used primarily by senior-level undergraduate students and graduate students in electrical en­ gineering, computer engineering, and computer science This book will also prove useful to practicing engineers who wish to learn specific MATLAB applications for communication systems We assume that the reader is familiar with the fundamentals of MATLAB We not cover those topics because several tutorial books and manuals on MATLAB are available By design, the treatment of the communications theory topics is brief We provide the motivation and a short introduction to each topic, establish the necessary notation, and then illustrate the basic notions through an example The primary text and the in­ structor are expected to provide the required depth for the topics treated For example, we introduce the matched filter and the correlator and assert that these devices result in the optimum demodulation of signals corrupted by additive white Gaussian noise (AWGN), but we not provide a proof of this assertion Such a proof generally is given in most core textbooks on communication systems NEW TO THIS EDITION • Three brand new chapters have been added on OFDM, multiple antenna sys­ tems, and digital transmission on fading channels • New examples with more practical real-life engineering problems have been included to help students cope better when they go to work in industry This will also help practicing engineers using this book to get exposure on communica­ tions systems • New sections have been added on DPCM, ADPCM, and DM; turbo codes and decoding; LDPC codes and decoding iii Copyright 2011 Cengage Leaming AJl Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Leaming reserves the right to remove additiona1 content at any time if subsequent rights restrictions require it IV • This third edition has been updated to make it compliant with the latest version of MATLAB • A revised and updated Simulink supplement with tutorial problems is now available online ORGANIZATION OF THE BOOK The book consists of 13 chapters The first two chapters on signals and linear sys­ tems and on random processes treat the basic background that is generally required in the study of communication systems One chapter is on analog communication tech­ niques, another is on analog to digital conversion, and the next eight chapters focus on digital communications The final chapter supports the Simulink tutorial, which is not included in the print version of the book, rather it is available online on the book's student companion website Chapter 1: Signals and Linear Systems This chapter provides a review of the basic tools and techniques from linear systems analysis, including both time-domain and frequency-domain characterizations We em­ phasize frequency-domain-analysis techniques, because these techniques are used most frequently in the treatment of communication systems Chapter 2: Random Processes This chapter illustrates methods for generating random variables and samples of ran­ dom processes The topics include the generation of random variables with a specified probability distribution function, the generation of samples of Gaussian and Gauss­ Markov processes, and the characterization of stationary random processes in the time domain and the frequency domain The chapter also treats the estimation of probabili­ ties via Monte Carlo simulation Chapter 3: Analog Modulation This chapter treats the performances of analog modulation and demodulation tech­ niques in the presence and absence of additive noise Systems studied include ampli­ tude modulation (AM), such as double-sideband AM, single-sideband AM, and con­ ventional AM, and angle-modulation schemes, such as frequency modulation (FM) and phase modulation (PM) Chapter 4: Analog-to-Digital Conversion This chapter treats various methods for converting analog source signals into digital sequences efficiently This conversion process allows us to transmit or store the signals digitally We consider both lossy data compression schemes, such as pulse-code mod­ ulation (PCM), differential PCM (DPCM), delta modulation (DM), and lossless data compression, such as Huffman coding Vector quantization and the K-means algorithm are also described and simulated in this chapter Copyright 2011 Cengage Leaming AJI Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to eJectronic rights, some third party content may be suppressed from the eBook andlor eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions l'«tuire it v Chapter 5: Baseband Digital Transmission This chapter introduces baseband digital modulation and demodulation techniques for transmitting digital information through an AWGN channel We consider both binary and non-binary modulation techniques We describe the optimum demodulation of these signals and evaluate the performance of the demodulator Chapter 6: Digital Transmission Through Band-limited Channels This chapter considers the characterization of band-limited channels and the problem of designing signal waveforms for such channels We show that channel distortion results in inter symbol interference (ISi), which causes errors in signal demodulation Then, we treat the design of channel equalizers that compensate for channel distortion Chapter 7: Digital Transmission via Carrier Modulation This chapter considers four types of carrier-modulated signals that are suitable for transmission through bandpass channels: amplitude-modulated signals, quadrature amplitude-modulated signals, phase-shift keying, and frequency-shift keying Chapter 8: Multicarrier Modulation and OFDM This chapter treats the transmission of digital information in a communication channel by use of frequency division multiplexing The channel bandwidth is subdivided into a large number of subbands and signals are transmitted by modulating the subcarrier in each of the subbands By performing the modulation of the subcarriers synchronously in time, the subcarrier signals are mutually orthogonal, thus resulting in an orthogonal frequency division multiplexed (OFDM) signal The topics treated in this chapter in­ clude the generation and demodulation of OFDM signals, the spectral characteristics of OFDM signals, the use of a cyclic prefix to suppress channel dispersion, and methods to limit the peak-to-average ratio (PAR) in OFDM signals Chapter 9: Transmission Through Wireless Channels This chapter is focused on digital signal transmission through wireless communication channels that are characterized by randomly time-variant and time-dispersive impulse responses Topics treated include the characteristics of frequency selective and fre­ quency nonselective Rayleigh fading channels models, modeling of the Doppler power spectrum, diversity transmission and reception techniques, the RAKE demodulator, OFDM transmission in frequency selective channels, and the error rate performance of digital transmission in Rayleigh fading channels Chapter 10: Channel Capacity and Coding This chapter considers appropriate mathematical models for communication channels and introduces a fundamental quantity, the channel capacity that gives the limit on the amount of information that can be transmitted through the channel In particular, we examine two channel models, the binary symmetric channel (BSC) and the additive Copyright 2011 Cengage Learning AU Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to e)ectronic rights, some third party content may be suppressed from the eBook andlor eChapter(s) E.clitorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it vi white Gaussian noise (AWGN) channel, which are used in the treatment of block and convolutional codes for achieving reliable communication through such channels The chapter concludes with a discussion of iterative decoding techniques for turbo and low density parity-check codes Chapter 11: Multiple Antenna Systems This chapter treats the use of multiple transmit and receive antennas (multiple-input, multiple-output or MIMO systems) that exploit the spatial domain to increase the data rate and improve the performance of wireless communication systems Topics treated include channel models for multiple antenna (MIMO) systems, signal modulation and demodulation in multiple antenna (MIMO) systems, the capacity of MIMO channels, and space-time block and trellis codes for MIMO systems Chapter 12: Spread Spectrum Communication Systems This chapter treats the basic elements of a spread-spectrum digital communication sys­ tem In particular, it considers direct sequence (DS) spread spectrum and frequency hopped (FH) spread spectrum systems in conjunction with phase-shift keying (PSK) and frequency-shift keying (FSK) modulation, respectively It also treats the genera­ tion of pseudo-noise (PN) sequences for use in spread spectrum systems Chapter 13: Simulink Tutorial on Digital Modulation Methods This chapter is devoted to an introduction to Simulink and its applications in simu­ lation of digital modulation systems The chapter begins with a tutorial introduction to Simulink that covers fundamentals of system simulation Subsequent sections of this chapter present many examples of simulation of various digital communication schemes This chapter is available on the student companion website of the book ANCILLARIES AND SUPPLEMENTS Student Companion Website The student companion website for this book is a free resource that can be accessed by both students and instructors Chapter 13 of the book is available on the student companion website as a PDF file This website also includes all the MATLAB and Simulink files used in the text The files are in separate directories that correspond to the chapters of the book Some MATLAB files appear in more than one directory because they are used in more than one chapter Numerous comments added to most files make them easier to understand In developing the files, however, our main objective has been the clarity of the code rather than its efficiency Where efficient code could have been difficult to follow, we have used less efficient but more readable code To use the software, copy the files to your personal computer and add the corresponding paths to your MATLAB search path All files have been tested using MATLAB R2011a Instructor Companion Website The instructor companion website is specially de­ signed for use by instructors and can only be accessed by registered instructors This Copyright 2011 Cengage Leaming AJI Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to eJectronic rights, some third party content may be suppressed from the eBook andlor eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions l'«tuire it vu website includes teaching aids such as PowerPoint files for the figures and tables and Cengage Learning's unique Lecture Builder resources Access Information To access the websites and additional course materials, please visit www.cengagebrain.com At the cengagebrain.com home page, search for the ISBN of your title (from the back cover of your book) using the search box at the top of the page T his will take you to the product page where these resources can be found ACKNOWLEDGEMENTS T he Simulink tutorial is a modified and extended version of a lab course developed at the Institute for Communications Engineering (LN T), Munich University of Technol­ ogy ( TUM) We thank Professor Joachim Hagenauer for supporting the book project and for giving permission to use the software We also thank Christian Buchner and Christoph Renner who did a large part of the programming work Furthermore, we would like to thank MathWorks for the permission to provide some Simulink blocks which are not included in the standard student version Particularly, we thank Stuart McGarrity, Mike McLernon and Alan Hwang from MathWorks for their helpful ad­ vice We also thank Mehmet Aydinlik and Osso Vahabzadeh for their assistance in developing the MATLAB code for the Illustrative Problems contained in this book We thank the reviewers of this edition, Nagwa Bekir of the California State Uni­ versity, Northridge, Tolga Duman of Arizona State University, Hyuck M Kwon of Wichita State University, and Ting-Chung Poon of Virginia Polytechnic Institute and State University, for their helpful comments John Proakis Masoud Salehi Gerhard Bauch Copyright 2011 Cengage Leaming AJI Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to eJectronic rights, some third party content may be suppressed from the eBook andlor eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions l'«tuire it Copyright 2011 Cengage Learning AJI Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 566 CHAPTER 12 SPREAD SPECTRUM COMMUNICATION SYSTEMS SNR required in AWGN is about 10 dB Consequently, the loss in SNR due to the pres­ ence of the partial-band interference is approximately 50 dB, which is excessively high The way to reduce the effect of partial-band interference on the FH spread spectrum system is through signal diversity; that is, the same information bit is transmitted on multiple frequency hops, and the signals from the multiple transmissions are weighed and combined together at the input to the detector To be specific, suppose that each information bit is transmitted on two successive frequency hops The resulting system is called a dual diversity system In this case, assuming that a is transmitted, either the two inputs to the combiner are both corrupted by interference, or one of the two trans­ mitted signals is corrupted by interference, or neither of the two transmitted signals is corrupted by interference The combiner is assumed to know the level of the interference and, thus, forms the combined decision variables, x y = = W1 rn + wzr12 w1 rz1 + wzrzz (12.4.6) where rn, rz1 are the two outputs of the square-law device for the first transmitted signal and r12, rzz are the outputs of the square-law device from the second transmitted signal The weights w1 and wz are set to / u2 , where u2 is the variance of the additive noise plus interference Hence, when u2 is large, as would be the case when interference is present, the weight placed on the received signal is small On the other hand, when u2 is small, as would be the case when there is no interference, the weight placed on the received signal is large Thus, the combiner deemphasizes the received signal components that are corrupted by interference The two components x and y from the combiner are fed to the detector, which decides in favor of the larger signal component The performance of the FH signal with dual diversity is now dominated by the case in which both signal transmissions are corrupted by interference However, the probability of this event is proportional to oc2, which is significantly smaller than oc As a consequence, the probability of error for the worst-case partial-band interference has the form Pb > where Kz is a constant and Pb = (12.4.7) EbI Jo In this case, the probability of error for dual diversity decreases inversely as the square of the SNR In other words, an increase in SNR by a factor of 10 (10 dB) results in a decrease of the error probability by a factor of 100 Consequently, an error probability of 10-6 can be achieved with an SNR of about 30 dB with dual diversity, compared to 60 dB (1000 times larger) for no diversity More generally, if each information bit is transmitted on Dfrequency hops, where Dis the order of diversity, the probability of error has the form Pb > (12.4.8) where Kn is a constant Copyright 2011 Cengage Leaming AJI Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to eJectronic rights, some third party content may be suppressed from the eBook andlor eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions l'«tuire it 12.4 FREQUENCY-HOPPED SPREAD SPECTRUM 567 Because signal diversity as described above is a trivial form of coding (repetition coding), it is not surprising to observe that instead of repeating the transmission of each information bit D times, we may use a code with a minimum Hamming distance equal to D and soft-decision decoding of the outputs from the square-law devices tilli-il;fulWiij;t•]:Jlill Illustrative Problem 12.8 [Diversity in FH Systems] Repeat the Monte Carlo simu­ lation for the FH system considered in Illustrative Problem 12.7, but now employ dual diversity In the absence of interference, the weight used in the combiner is set to w 10, which corresponds to a0.1, a value that may be typical of the level of the additive = = Gaussian noise On the other hand, when interference is present, the weight is set to w l/a2/E, where E is constrained to be E ;;:::: The SNR per hop is E, and = = the total energy per bit in the two hops is Eb = 2E Therefore, the error probability is plotted as a function of Eb I Jo The results of the Monte Carlo simulation are illustrated in Figure 12.15 The MATLAB scripts for the simulation program are given next Figure 12.15: Error rate performance of FH dual diversity binary FSK with partial-band interference-Monte Carlo simulation Iii" -% MATLAB script for Illustrative Problem 12.8 echo on Copyright 2011 Cengage Leaming AJI Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to eJectronic rights, some third party content may be suppressed from the eBook andlor eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions l'«tuire it CHAPTER 12 SPREAD SPECTRUM COMMUNICATION SYSTEMS 568 % rho in dB rho_b=0:2:24; for i=1 :length(rho_b), smld_err_prb(i)=ss_Pe97 (rho_b(i)); % simulated error rate echo off ; end; echo on ; % Plotting commands follow tllli" -function [p]=ss_Pe97 (rho_in_dB) % [p]=ss_pe97(rho_in-

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