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SIGNALS AND COMMUNICATION TECHNOLOGY

For further volumes:http://www.springer.com/series/4748

Dayan Adionel Guimaraes

Digital Transmission

A Simulation-Aided Introductionwith VisSim/Comm

123

Prof. Dayan Adionel GuimaraesInstituto Nacional de Telecomunicacoes (Inatel)Santa Rita do Sapucaı - [email protected]

ISBN 978-3-642-01358-4 e-ISBN 978-3-642-01359-1DOI 10.1007/978-3-642-01359-1Springer Heidelberg Dordrecht London New York

Library of Congress Control Number: 2009940806

c© Springer-Verlag Berlin Heidelberg 2009This work is subject to copyright. All rights are reserved, whether the whole or part of the material isconcerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting,reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publicationor parts thereof is permitted only under the provisions of the German Copyright Law of September 9,1965, in its current version, and permission for use must always be obtained from Springer. Violationsare liable to prosecution under the German Copyright Law.The use of general descriptive names, registered names, trademarks, etc. in this publication does notimply, even in the absence of a specific statement, that such names are exempt from the relevant protectivelaws and regulations and therefore free for general use.

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To my son, Yan Guimaraes

Preface

Here it is standing: atoms with consciousness; matter withcuriosity. Stands at the sea, wondering: I. . . a universe ofatoms, an atom in the universe.

Richard Feynman

While teaching classes on digital transmission and mobile communications forundergraduate and graduate students, I was wondering if it would be possible towrite a book capable of giving them some insight about the practical meaning of theconcepts, beyond the mathematics; the same insight that experience and repetitivecontact with the subject are capable to construct; the insight that is capable of build-ing the bridge between the theory and how the theory manifests itself in practice.

I remember those days when I was a graduate student at State University ofCampinas (Unicamp), SP, Brazil, and those lectures given with competence by myprofessors. At that time, for me and for most of the students, some topics werenebulous, except by the fact that a few times we were able to follow the mathemat-ics. Something that could translate mathematics into waveforms, block diagrams,circuits and the like was missing from the student’s point of view.

Later, in 1999 I took contact with one of the first versions of VisSim/Comm,a communication’s systems simulation software jointly developed by Visual Solu-tions, Inc. (http://www.vissol.com/) and Eritek, Inc. (http://www.eritek.com/). Istarted using VisSim/Comm just to help me better understand the subjects I wasstudying while preparing my lecture materials. Soon I realized that the softwarecould be used in a similar way to help students to understand the concepts that Iwas teaching them. Then I began to use VisSim/Comm as a teaching tool, show-ing previously prepared simulations to the students just after the mathematical orconceptual explanation about some topic.

The students gave me very positive feedback about the idea, but insisted to claimthat, unconditionally, “theory is different from practice” in what concerns communi-cation systems. As a reply I always told them that this is an unfair judgment. Theorywould produce, and sometimes actually produces the same results as actual sys-tems, as long as the mathematical model of the system under analysis is able to takeinto account all or most of the relevant system variables. Theory is different from

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practice in cases where it is impossible or mathematically intractable to consider allimportant system variables. We must live with this difference. Otherwise, we wouldhave nothing to do. Eventually I felt that we have reached to a balance. . .

This book is the result of such experience. Discussing with my students andpreparing class notes and simulations throughout these years have given to me theopportunity to resolve my past wonderings.

This is not a conventional textbook on Digital Transmission, nor a book on Sim-ulation of Communications Systems. The literature is rich, and it is not difficult tofind excellent books about these areas. Furthermore, it would be an act of arroganceto aim at preparing a book to “compete” with those from where I have learned whatwould be presented in such book.

This book addresses basic concepts on digital transmission, mainly pertaining tothe physical layer of a digital communication system. However, these basic conceptsare also intended to allow the reader to understand more advanced topics and theassociated technology. Each topic is addressed in two different and complemen-tary ways: theoretically and by simulation. The theoretical approach encompassescommon subjects covering principles of digital transmission, like notions of proba-bility and stochastic processes, signals and systems, baseband and passband signal-ing, signal-space representation, spread spectrum, multi-carrier and ultra widebandtransmissions, carrier and symbol-timing recovery, information theory and error-correcting codes. The simulation approach also covers these subjects, but with focuson the capabilities of VisSim/Comm to help the reader fulfill the gap between thetheory and its practical meaning. The presentation of the theory is made easier withthe help of 357 illustrations. A total of 101 simulation files support the simulation-oriented approach.

Although the computer experiments can be considered themselves as exercisesto test the reader’s knowledge, some additional problems are proposed inside thesimulation work plans and a few more are proposed at the end of each chapter.Most of the proposed problems are simulation-oriented in the sense that the reader isguided to create specific simulations for exploring the practical meaning of conceptsnot explicitly covered before, for complementing those already covered, or simplyfor revisiting a given concept with a different perspective. A significant part of theremaining problems deals with the study of specific topics, aiming at complement-ing some theory.

All simulation files used throughout the book are supplied in the accompanyingCD and run with an evaluation version of VisSim/Comm, which is also available inthe CD. This evaluation version allows for users to run all examples included in theCD and construct new diagrams, but not save their work. Nevertheless, if the readeris able to afford a full version of VisSim/Comm, he can benefit from the opportunityof enhancing his knowledge through a deeper interaction with the supplied files,adding the possibility of saving changes and new diagrams.

It is not expected that the reader has previous knowledge about VisSim/Comm,neither about simulation of communication systems. However, a previous contactwith the VisSim/Comm documentation may help the reader to achieve an easierand faster interaction with the simulation files and, as a consequence, to speed-up

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his learning process. The only previous knowledge that is needed to follow thisbook refers to notions of communication systems and a solid background in whatconcerns the mathematics covered in typical Electrical Engineering courses.

Both theoretical and simulation parts of the book can be followed independently,though some simulation results will require comparisons with theoretical ones. Itis left to the reader’s discretion to go through the entire book sequence or to skipthe simulation and go only through the theory and vice-versa. However, for a morecomplete treatment of each topic, it is recommended that both are followed in theoriginal sequence.

The depth and scope of the book is adequate mainly for undergraduate level,though first-level graduate students can also benefit from the simulation approachadopted. The book can be used as a textbook for a two-semester undergraduatecourse or for a one-semester graduate and introductory course on digital commu-nications. An important consequence of the simulation appeal is that the computerexperiments can be explored as laboratory activities, expanding the course possibil-ities. Furthermore, the book can be used as a reference for VisSim/Comm users.

In what concern the bibliographical references, I have adopted the approach ofproviding a huge number of references throughout the text, not only to acknowledgethose who have contributed to the field, but also to give the reader the opportunityof complementing his studies or finding details not presented here.

Finally, one might be worried about the caducity of the accompanying softwareversion and of the book itself. However, since we are dealing with fundamentalsand well-established concepts, and since upgrades of VisSim/Comm will always bebackward-compatible, this work promises to be a life-long textbook that will helpthe readers to improve their knowledge on digital transmission for a long time. Atleast, this is what I expect.

Contents

1 A Review of Probability and Stochastic Processes . . . . . . . . . . . . . . . . . . 11.1 Set Theory Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1.1 The Venn Diagram and Basic Set Operations . . . . . . . . . . . . . 21.1.2 Other Set Operations and Properties . . . . . . . . . . . . . . . . . . . . . 3

1.2 Definitions and Axioms of Probability . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Counting Methods for Determining Probabilities . . . . . . . . . . . . . . . . 5

1.3.1 Distinct Ordered k-Tuples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.3.2 Sampling with Replacement and with Ordering . . . . . . . . . . . 61.3.3 Sampling Without Replacement and with Ordering . . . . . . . . 61.3.4 Permutation of Distinct Objects . . . . . . . . . . . . . . . . . . . . . . . . 61.3.5 Sampling Without Replacement and Without Ordering . . . . . 61.3.6 Sampling with Replacement and Without Ordering . . . . . . . . 7

1.4 Conditional Probability and Bayes Rule . . . . . . . . . . . . . . . . . . . . . . . . 7Simulation 1.1 – Conditional Probability . . . . . . . . . . . . . . . . . . . . . . . 9

1.5 Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.5.1 The Cumulative Distribution Function . . . . . . . . . . . . . . . . . . . 101.5.2 Types of Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.6 Conditional Probability Densities and Mass Functions . . . . . . . . . . . . 161.6.1 The Bayes Rule Revisited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.6.2 The Total Probability Theorem Revisited . . . . . . . . . . . . . . . . 17

1.7 Statistical Averages of Random Variables . . . . . . . . . . . . . . . . . . . . . . . 171.7.1 Mean of Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.7.2 Moments of Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . 191.7.3 Joint Moments of Random Variables . . . . . . . . . . . . . . . . . . . . 201.7.4 The Characteristic and the Moment-Generating Functions . . 211.7.5 Conditional Expected Value . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.8 Some Discrete Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231.8.1 Bernoulli Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231.8.2 Binomial Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241.8.3 Geometric Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . 241.8.4 Poisson Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Simulation 1.2 – Discrete Random Variables . . . . . . . . . . . . . . . . . . . . 26

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1.9 Some Continuous Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . . 271.9.1 Uniform Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271.9.2 Exponential Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . 281.9.3 Gaussian Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291.9.4 Rayleigh Random Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Simulation 1.3 – Continuous Random Variables . . . . . . . . . . . . . . . . . 321.9.5 Multivariate Gaussian Random Variables . . . . . . . . . . . . . . . . 34

1.10 Sum of Random Variables and the Central Limit Theorem . . . . . . . . . 351.10.1 Mean and Variance for the Sum of Random Variables . . . . . . 351.10.2 Moments of the Sum of Random Variables . . . . . . . . . . . . . . . 361.10.3 PDF of the Sum of Random Variables . . . . . . . . . . . . . . . . . . . 361.10.4 The Central Limit Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

1.11 Transformations of Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . 38Simulation 1.4 – A Communication System Analysis . . . . . . . . . . . . 46

1.12 Parameter Estimation via Sample Mean . . . . . . . . . . . . . . . . . . . . . . . . 471.12.1 The Sample Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481.12.2 The Confidence Interval on the Sample Mean . . . . . . . . . . . . . 50Simulation 1.5 – Confidence Interval on BER Estimations . . . . . . . . 531.12.3 The Law of Large Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

1.13 Generation of Random Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551.13.1 Congruential Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 561.13.2 Inverse CDF Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 561.13.3 Acceptance/Rejection Methods . . . . . . . . . . . . . . . . . . . . . . . . . 571.13.4 Box-Muller Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Simulation 1.6 – Random Numbers Generation . . . . . . . . . . . . . . . . . . 58

1.14 Random Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Simulation 1.7 – The Concept of Random Process . . . . . . . . . . . . . . . 621.14.1 Stationarity Classes for Random Processes . . . . . . . . . . . . . . . 631.14.2 Averages of Stationary Random Processes . . . . . . . . . . . . . . . 64Simulation 1.8 – Estimating Averages of Random Processes . . . . . . . 711.14.3 Random Processes Through Linear Systems . . . . . . . . . . . . . . 731.14.4 The Gaussian Random Process . . . . . . . . . . . . . . . . . . . . . . . . . 76Simulation 1.9 – Filtered Complex Gaussian Process . . . . . . . . . . . . . 771.14.5 Thermal Noise Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

1.15 Summary and Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 821.16 Additional Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

2 Signals and Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872.1 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

2.1.1 Classification of Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872.1.2 Typical Deterministic Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 90

2.2 Fourier Analysis of Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 942.2.1 Fourier Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

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Simulation 2.1 – Gibbs Phenomenon . . . . . . . . . . . . . . . . . . . . . . . . . . 972.2.2 Continuous-Time Fourier Transform . . . . . . . . . . . . . . . . . . . . 1002.2.3 Discrete-Time Fourier Transform . . . . . . . . . . . . . . . . . . . . . . . 1062.2.4 Discrete Fourier Transform . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108Simulation 2.2 – The FFT via VisSim/Comm . . . . . . . . . . . . . . . . . . . 1112.2.5 Laplace and Z-Transforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

2.3 Sampling of Deterministic and Random Signals . . . . . . . . . . . . . . . . . 1152.3.1 Ideal Sampling of Deterministic Signals . . . . . . . . . . . . . . . . . 1152.3.2 Ideal Sampling of Stochastic Processes . . . . . . . . . . . . . . . . . . 1172.3.3 Practical Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Simulation 2.3 – Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1202.3.4 Analog-to-Digital Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . 122Simulation 2.4 – Uniform and Non-uniform Quantization . . . . . . . . . 127

2.4 Linear Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1302.4.1 Time-Domain Characterization of Linear Systems . . . . . . . . . 1302.4.2 Frequency-Domain Characterization of Linear Systems . . . . 1322.4.3 Classifications and Properties of Linear Systems . . . . . . . . . . 1352.4.4 Mapping a Discrete-Time into a Continuous-Time Frequency139Simulation 2.5 – Moving Average Filter . . . . . . . . . . . . . . . . . . . . . . . . 142

2.5 Complex Representation of Signals and Systems . . . . . . . . . . . . . . . . . 146Simulation 2.6 – Real Versus Complex Simulation . . . . . . . . . . . . . . . 148

2.6 The Power Spectral Density Revisited . . . . . . . . . . . . . . . . . . . . . . . . . 1502.6.1 The PSD of Passband Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 150Simulation 2.7 – Estimating the PSD of Passband Signals . . . . . . . . . 1532.6.2 Estimation of the PSD via the Periodogram . . . . . . . . . . . . . . 155Simulation 2.8 – Periodogram Estimation of the PSD . . . . . . . . . . . . 1562.6.3 The PSD of Baseband Digital Communication Signals . . . . . 159

2.7 The Bandwidth of Communication Signals . . . . . . . . . . . . . . . . . . . . . 1622.7.1 Absolute Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1622.7.2 −3 dB (or Half Power) Bandwidth . . . . . . . . . . . . . . . . . . . . . . 1632.7.3 Equivalent Noise Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . 1632.7.4 Root Mean Square (rms) Bandwidth . . . . . . . . . . . . . . . . . . . . 1632.7.5 Null-to-Null or Main Lobe Bandwidth . . . . . . . . . . . . . . . . . . . 1642.7.6 Spectral Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165


3 Communication Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1713.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

3.1.1 Communication Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1713.1.2 Channel Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1743.1.3 Channel Sounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1743.1.4 Empirical, Deterministic and Stochastic Channel Models . . . 175

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3.2 AWGN Channel Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1753.2.1 Vector AWGN Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176Simulation 3.1 – Waveform and Vector Channel Simulation . . . . . . . 178

3.3 Discrete Memoryless Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1803.3.1 The Binary Symmetric Channel Revisited . . . . . . . . . . . . . . . . 181Simulation 3.2 – Waveform and BSC Channel Simulation . . . . . . . . . 181

3.4 Discrete Channels with Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1833.5 Wireline Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

3.5.1 Twisted Pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1843.5.2 Coaxial Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1873.5.3 Waveguide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1893.5.4 Optical Fiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1903.5.5 Low-Voltage Power-Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

3.6 Wireless Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1993.6.1 Mobile Outdoor Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199Simulation 3.3 – Large-Scale and Small-Scale Propagation . . . . . . . . 208Simulation 3.4 – Mobile Channel Simulator . . . . . . . . . . . . . . . . . . . . 217Simulation 3.5 – Exploring the Coherence Bandwidth . . . . . . . . . . . . 226Simulation 3.6 – Exploring the Coherence Time . . . . . . . . . . . . . . . . . 227Simulation 3.7 – Flat and Frequency Selective Channel . . . . . . . . . . . 229Simulation 3.8 – A Modulated Signal Under Selective Fading . . . . . 2313.6.2 Mobile Indoor Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232Simulation 3.9 – Saleh-Valenzuela Indoor Channel Model . . . . . . . . 2373.6.3 Terrestrial Microwave Channel . . . . . . . . . . . . . . . . . . . . . . . . . 239Simulation 3.10 – Rummler Terrestrial Microwave Channel Model . 2473.6.4 Spatial Wireless Channel Models . . . . . . . . . . . . . . . . . . . . . . . 2503.6.5 Other Wireless Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252


4 Baseband Digital Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2654.1 Definitions and Typical Baseband Signals . . . . . . . . . . . . . . . . . . . . . . 265

4.1.1 Line Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266Simulation 4.1 – Line Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2724.1.2 M-ary PAM Signaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273Simulation 4.2 – M-ary PAM Signaling . . . . . . . . . . . . . . . . . . . . . . . . 276

4.2 Detection of Baseband Pulses in Noise . . . . . . . . . . . . . . . . . . . . . . . . . 2784.2.1 Modeling and Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278Simulation 4.3 – Motivation for Baseband Detection Analysis . . . . . 2794.2.2 The Matched Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284Simulation 4.4 – Pulse Signal-to-Noise Ratio Measurement . . . . . . . 2864.2.3 Equivalence Between the Matched Filter and the Correlator 289Simulation 4.5 – Equivalence Matched Filter × Correlator . . . . . . . . 292

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4.2.4 Error Probability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294Simulation 4.6 – Equivalence Matched Filter × Correlator Revisited 3024.2.5 MAP and ML Decision Rules for Binary Transmission . . . . . 304

4.3 Intersymbol Interference (ISI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3074.3.1 Distortion-Free Channel and ISI Channel . . . . . . . . . . . . . . . . 307Simulation 4.7 – Distortion-Free Channel . . . . . . . . . . . . . . . . . . . . . . 3104.3.2 Nyquist Criterion for ISI-Free Transmission . . . . . . . . . . . . . . 312Simulation 4.8 – Vestigial Symmetry . . . . . . . . . . . . . . . . . . . . . . . . . . 3154.3.3 The Raised Cosine Spectrum. . . . . . . . . . . . . . . . . . . . . . . . . . . 3174.3.4 The Root-Raised Cosine Spectrum . . . . . . . . . . . . . . . . . . . . . . 319Simulation 4.9 – Nyquist Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3204.3.5 The Eye Diagram and the Bathtub Diagram . . . . . . . . . . . . . . 323Simulation 4.10 – Eye Diagram for M-PAM Signaling . . . . . . . . . . . 325Simulation 4.11 – Bathtub Diagram for Binary Signaling . . . . . . . . . 331

4.4 Correlative Coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333Simulation 4.12 – Polybinary and Polybipolar Signal Generation . . . 3344.4.1 Duobinary and Modified Duobinary Signaling . . . . . . . . . . . . 3354.4.2 Generalized Partial Response Signaling . . . . . . . . . . . . . . . . . . 340Simulation 4.13 – Duobinary Signaling Using a Matched Filter . . . . 341

4.5 Notions of Channel Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3434.5.1 Zero Forcing (ZF) Equalization . . . . . . . . . . . . . . . . . . . . . . . . 344Simulation 4.14 – ZF Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3474.5.2 Least Mean Square (LMS) Equalization . . . . . . . . . . . . . . . . . 349Simulation 4.15 – LMS Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . 354


5 Signal-Space Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3615.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3615.2 Geometric Representation of Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 3635.3 Dimensionality of a Signal and of a Signal-Space . . . . . . . . . . . . . . . . 3665.4 Gram-Schmidt Orthogonalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3675.5 Signal Constellation with Symbol Transitions . . . . . . . . . . . . . . . . . . . 3705.6 Statistics of the Correlator’s Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . 371

Simulation 5.1 – Signal Space Analysis . . . . . . . . . . . . . . . . . . . . . . . . 3765.7 The Vector AWGN Channel Revisited . . . . . . . . . . . . . . . . . . . . . . . . . 378

Simulation 5.2 – The Vector AWGN Channel Revisited . . . . . . . . . . . 3795.8 Generalized Maximum Likelihood Receiver . . . . . . . . . . . . . . . . . . . . 381

Simulation 5.3 – Generalized ML Receiver . . . . . . . . . . . . . . . . . . . . . 3855.9 Error Probability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387

5.9.1 Rotation and Translation Invariance of the Error Probability 3875.9.2 Minimum Energy Constellation . . . . . . . . . . . . . . . . . . . . . . . . 388Simulation 5.4 – Constellation Rotation and Translation . . . . . . . . . . 389

xvi Contents

5.9.3 The Union Bound for Symbol Error Probability Estimation . 391Simulation 5.5 – Verifying the Validity of the Union Bound . . . . . . . 3945.9.4 Symbol Versus Bit Error Probability . . . . . . . . . . . . . . . . . . . . 396Simulation 5.6 – Symbol Error Rate versus Bit Error Rate . . . . . . . . 401

5.10 Symbol-by-Symbol ML Receiver for Channels with ISI . . . . . . . . . . . 4025.11 Summary and Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4055.12 Additional Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409

6 Passband Digital Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4116.1 Definitions and Basic Digital Modulation Schemes . . . . . . . . . . . . . . . 411

6.1.1 Basic Digital Modulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4126.1.2 Coherent and Non-coherent Detection . . . . . . . . . . . . . . . . . . . 4136.1.3 Spectral Efficiency and Power Efficiency . . . . . . . . . . . . . . . . 4136.1.4 A Note on a Frequently Used Notation . . . . . . . . . . . . . . . . . . 414

6.2 M-PSK Modulations with Coherent Detection . . . . . . . . . . . . . . . . . . 4156.2.1 Binary PSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415Simulation 6.1 – BPSK Generation and Coherent Detection . . . . . . . 4206.2.2 M-ary PSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422Simulation 6.2 – M-PSK Generation and Coherent Detection . . . . . . 432

6.3 M-QAM Modulations with Coherent Detection . . . . . . . . . . . . . . . . . 4346.3.1 M-QAM Modulated Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4346.3.2 M-QAM Base-Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4356.3.3 Square M-QAM Modulations . . . . . . . . . . . . . . . . . . . . . . . . . . 4356.3.4 Non-square M-QAM Modulations . . . . . . . . . . . . . . . . . . . . . . 4376.3.5 M-QAM Generation and Coherent Detection . . . . . . . . . . . . . 439Simulation 6.3 – I&Q Generation of a 32-QAM and a 64-QAM . . . . 4416.3.6 M-QAM Symbol and Bit Error Probability over the

AWGN Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4426.3.7 Power Spectral Density of an M-QAM Modulated Signal . . 4466.3.8 Spectral Efficiency of an M-QAM Modulated Signal . . . . . . 447Simulation 6.4 – M-QAM Generation and Coherent Detection . . . . . 4476.3.9 Comparing M-PSK and M-QAM Modulations . . . . . . . . . . . 449

6.4 M-FSK Modulations with Coherent Detection . . . . . . . . . . . . . . . . . . 4506.4.1 Tone Separation and Carrier Frequency for Orthogonality . . 4506.4.2 Binary FSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451Simulation 6.5 – Analysis of Tones Used by an FSK Modulation . . . 456Simulation 6.6 – BFSK Modulation Methods . . . . . . . . . . . . . . . . . . . 4616.4.3 M-ary FSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464Simulation 6.7 – M-FSK Generation and Coherent Detection . . . . . . 471

6.5 MSK Modulation with Coherent Detection . . . . . . . . . . . . . . . . . . . . . 4756.5.1 MSK Signal Generation and Detection . . . . . . . . . . . . . . . . . . 476Simulation 6.8 – BFSK and FFSK Generation via VCO . . . . . . . . . . 479

Contents xvii

Simulation 6.9 – MSK Generation via Complex Representation . . . . 483Simulation 6.10 – MSK Generation via OQPSK Approach . . . . . . . . 486Simulation 6.11 – MSK Modem via OQPSK Approach . . . . . . . . . . . 488Simulation 6.12 – MSK Modem via Signal-Space Approach . . . . . . 4936.5.2 MSK Bit Error Probability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495Simulation 6.13 – MSK Modem Performance . . . . . . . . . . . . . . . . . . . 4966.5.3 MSK with Conventional FSK Detection . . . . . . . . . . . . . . . . . 497Simulation 6.14 – MSK with Conventional FSK Detection . . . . . . . . 5026.5.4 Power Spectral Density of the MSK Signal . . . . . . . . . . . . . . . 502Simulation 6.15 – Power Spectral Density of the MSK Signal . . . . . 5046.5.5 Further Attributes and Uses for the MSK Modulation . . . . . . 5056.5.6 Answering Some Questions About the MSK Modulation . . . 506

6.6 OQPSK, π /4QPSK and GMSK Modulations . . . . . . . . . . . . . . . . . . . . 507Simulation 6.16 – Distortion Caused by Nonlinear Amplification . . . 5086.6.1 Offset QPSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512Simulation 6.17 – OQPSK Signal Generation . . . . . . . . . . . . . . . . . . . 5146.6.2 π /4DQPSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 516Simulation 6.18 – π /4DQPSK Generation and Detection . . . . . . . . . 5206.6.3 GMSK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521Simulation 6.19 – GMSK Generation and Detection . . . . . . . . . . . . . 5276.6.4 Nonlinear Amplification Distortion Revisited . . . . . . . . . . . . . 529Simulation 6.20 – Nonlinear Amplification of Modulated Signals . . 530

6.7 Non-coherent M-FSK and Differentially Coherent BPSK . . . . . . . . . 5346.7.1 Non-coherent M-FSK Modulations . . . . . . . . . . . . . . . . . . . . . 534Simulation 6.21 – Non-coherently Detected Binary FSK . . . . . . . . . . 5386.7.2 Differentially-Coherent BPSK Modulation . . . . . . . . . . . . . . . 542Simulation 6.22 – DBPSK Generation and Detection . . . . . . . . . . . . . 545

6.8 Carrier and Symbol-Timing Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . 5466.8.1 Parameter Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5486.8.2 Carrier Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551Simulation 6.23 – PLL Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555Simulation 6.24 – BPSK Phase Tracking with Costas Loop . . . . . . . . 557Simulation 6.25 – M-th Power Loop for QPSK Phase Tracking . . . . 5616.8.3 Symbol Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564Simulation 6.26 – Operation of the Early-Late Synchronizer . . . . . . . 565Simulation 6.27 – Carrier and Symbol Synchronization . . . . . . . . . . . 568

6.9 Performance of Digital Modulations over Fading Channels . . . . . . . . 5706.9.1 Optimum Receiver Structures for Fading Channels . . . . . . . . 5706.9.2 The Effect of Fading on the Error Probability . . . . . . . . . . . . . 5716.9.3 Performance of Digital Modulations over Fading Channels . 573


xviii Contents

7 Wideband Transmission Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5857.1 Spread-Spectrum Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585

7.1.1 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5857.1.2 A Brief History About the Spread-Spectrum . . . . . . . . . . . . . . 5867.1.3 Direct-Sequence Spread-Spectrum . . . . . . . . . . . . . . . . . . . . . . 5877.1.4 Attributes of a Spread-Spectrum Signal . . . . . . . . . . . . . . . . . . 588Simulation 7.1 – DS-SS Signal Under Jamming . . . . . . . . . . . . . . . . . 591Simulation 7.2 – Channel Sounding . . . . . . . . . . . . . . . . . . . . . . . . . . . 596Simulation 7.3 – RAKE Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6087.1.5 Spreading Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611Simulation 7.4 – Generation of m-Sequences . . . . . . . . . . . . . . . . . . . 617Simulation 7.5 – White Noise Generation with m-Sequences . . . . . . 618Simulation 7.6 – Exploring Correlation Properties for Synchronism 620Simulation 7.7 – Exploring Correlation Properties for CDMA . . . . . 6277.1.6 Frequency-Hopping Spread-Spectrum . . . . . . . . . . . . . . . . . . . 629Simulation 7.8 – FH-SS Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6317.1.7 Processing Gain and Jamming Margin for DS-SS and FH-SS 6337.1.8 Acquisition and Tracking of Spread-Spectrum Signals . . . . . 634Simulation 7.9 – Serial-Search Acquisition . . . . . . . . . . . . . . . . . . . . . 636

7.2 Multi-carrier Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6407.2.1 Multi-carrier Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6417.2.2 Multi-carrier CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6427.2.3 Multi-carrier DS-CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6437.2.4 Multi-tone CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6447.2.5 Multi-carrier DS-CDMA using frequency-spread coding . . . 6447.2.6 Modified Multi-carrier DS-CDMA . . . . . . . . . . . . . . . . . . . . . . 6457.2.7 Implementation Aspects of MC-CDMA Systems . . . . . . . . . . 646Simulation 7.10 – OFDM Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6537.2.8 Comments on the Performance of MC-CDMA Systems . . . . 6567.2.9 MC-CDMA with Double Spreading Code . . . . . . . . . . . . . . . . 657Simulation 7.11 – DC-DS-CDMA Modem . . . . . . . . . . . . . . . . . . . . . 663

7.3 Ultra Wideband Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6657.3.1 UWB Signaling Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . 6667.3.2 UWB Channel Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6717.3.3 Reception of UWB Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 672Simulation 7.12 – TH-PPM Ultra Wideband Modem . . . . . . . . . . . . . 673Simulation 7.13 – Exploring the Time Reversal Technique . . . . . . . . 677


8 Notions of Information Theory and Error-Correcting Codes . . . . . . . . . 6898.1 Notions of Information Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 689

8.1.1 Uncertainty, Information and Entropy . . . . . . . . . . . . . . . . . . . 690

Contents xix

Simulation 8.1 – Estimating the Entropy of a Source . . . . . . . . . . . . . 6938.1.2 Source Coding and the Source-Coding Theorem . . . . . . . . . . 6948.1.3 Discrete Memoryless Channels Revisited . . . . . . . . . . . . . . . . 6998.1.4 Mutual Information and Channel Capacity . . . . . . . . . . . . . . . 7008.1.5 Channel Coding Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7018.1.6 Channel Capacity of Some Channels . . . . . . . . . . . . . . . . . . . . 7038.1.7 Channel Capacity of Other Important Channels . . . . . . . . . . . 710

8.2 Notions of Error-Correcting Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7298.2.1 Terminology and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 7298.2.2 Hamming and Reed-Muller Codes . . . . . . . . . . . . . . . . . . . . . . 7398.2.3 Syndrome Decoding of Binary Linear Block Codes . . . . . . . . 744Simulation 8.2 – Hard-Decision Versus Soft-Decision ML Decoding 746Simulation 8.3 – Coded and Uncoded System Performance . . . . . . . . 7498.2.4 Construction of Extension Fields and Polynomial Algebra . . 7518.2.5 Cyclic Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 753Simulation 8.4 – LFSR Encoding of a Hamming (7, 4) Code . . . . . . 762Simulation 8.5 – Meggitt Decoding of a Hamming (7, 4) Code . . . . . 7638.2.6 Bose-Chaudhuri-Hocquenghem and Reed-Solomon Codes . . 764Simulation 8.6 – Reed-Solomon Code Performance . . . . . . . . . . . . . . 7708.2.7 Performance of Binary Linear Block Codes . . . . . . . . . . . . . . 7728.2.8 Convolutional Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 776Simulation 8.7 – Finite Trace-Back Viterbi Decoding . . . . . . . . . . . . 786Simulation 8.8 – Convolutional Code Performance . . . . . . . . . . . . . . . 7948.2.9 Trellis-Coded Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 795Simulation 8.9 – Four-State 8PSK Trellis-Coded Modulation . . . . . . 8048.2.10 Turbo and Low-Density Parity Check Codes . . . . . . . . . . . . . . 8068.2.11 Remarks on Coding for Fading Channels . . . . . . . . . . . . . . . . 828


A Mathematical Tables and Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841A.1 Trigonometric Relations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841A.2 Gaussian Error Function and Gaussian Q-Function . . . . . . . . . . . . . . . 842

A.2.1 Some Tabulated Values of the ComplementaryError Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 843

A.3 Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 844A.4 Definite Integrals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 844A.5 Indefinite Integrals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 846A.6 Linear Matrix Transformations of Two-Dimensional Spaces . . . . . . . 847A.7 Mathcad Routine for Converting Decimal to Binary Numbers . . . . . . 848A.8 Mathcad Routine for a Binary Counter . . . . . . . . . . . . . . . . . . . . . . . . . 848A.9 Mathcad Routine for a Gray Counter . . . . . . . . . . . . . . . . . . . . . . . . . . 849

xx Contents

A.10 Mathcad Routine for Generating Walsh-Hadamard Sequences . . . . . 849A.11 Mathcad Routine for Generating the IOWEM of a Block Code . . . . . 849A.12 Mathcad Routine for Computing the Euler Function . . . . . . . . . . . . . . 850References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 851

Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 853

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 861

Structure of the Book

Chapter 1 aims at revisiting the mathematical basement on probability, randomvariables and random processes, since these topics are extensively used through-out the book. In Chap. 2, signals typically encountered in communication systemsare studied, aiming the analysis of their deterministic and random characteristics.While writing these first two chapters, I was wondering if I was being repetitiveand exaggeratedly concise, trying to condense a material vastly available in all goodbooks on Probability and Stochastic Processes and Signals and Systems. Eventually,I have decided to run into the risk and give a condensed review of some of the mainconcepts on these two areas. Some topics were in fact covered in a very simplisticway and I did this motivated by my students. During the past few years, I detectedseveral “holes” in their basic knowledge, and this was the main reason for coveringsuch simple and basic topics in Chaps. 1 and 2. By doing this, the students are notforced to resort to other references if some (not heavy) stone shows up in their waywhen studying the main chapters of the book.

Chapter 3 covers the communication channels over which most of the communi-cation systems convey information. The importance of this chapter and its locationresides in the fact that it is virtually impossible to design a communication systemwithout knowing the characteristics and behavior of the channel through which theinformation will flow.

In Chap. 4 the study of digital communication systems starts with one of itssimplest forms: baseband transmission. The concepts drawn from the discussionabout baseband transmission are applied in the study of passband transmission (ordigital modulation), a topic covered in Chap. 6.

Chapter 5 can be viewed as an interface or preparation for Chap. 6. Some toolsare developed so that a smooth transition is made between baseband and passbandtransmission. Additionally, most of the concepts discussed in Chap. 4 are general-ized in Chap. 6 by applying the tools developed in Chap. 5.

Spread spectrum, multicarrier, and ultra wideband are covered in Chap. 7. Thischapter can be viewed as an application of fundamental concepts presented in pre-vious chapters. However, several new concepts are presented in this chapter.

As a complementary and final part of the book, notions about information theoryand error-correcting codes are discussed in Chap. 8.

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xxii Structure of the Book

The material presented in this book can be more adequately explored dependingon the content of the curriculum of the course where it is intended to be applied.Chapters 1 and 2 can be skipped if there are courses on Probability and StochasticProcesses and on Signals and Systems. Nevertheless, it can be of help to recom-mend to the students a review of such topics before entering into the specifics ofdigital transmission. In this case the book can be covered in two 4-month terms inan undergraduate course and in one 4-month term in a graduate course. We mustnot forget that the computer experiments can be explored as laboratory activities tocomplement the theoretical studies. The majority of details and deeper analysis areconcentrated in Chaps. 3, 4, 5, 6, and 7, since these chapters can be considered themost relevant from the perspective of an introductory study about digital transmis-sion. Information theory and error-correcting codes normally are part of graduatecourses in communication systems. If this is the case, Chap. 8 can also be skippedand treated as a review.

Acknowledgement

I would like to express here my gratitude to several people that, in different ways,have helped me to conclude the preparation of this book. I express my deepest grat-itude to Flavia who, with love and patience, has believed in my project sometimeseven more than me, and who is the only one that really knows what I had left behindto make this dream come true. I also would like to thank my dear friend Prof. CarlosNazareth Motta Marins for the constant encouragement and unshakeable friendship.Special thanks also go to Ms. Adriana Maria Abrahao Martins for helping me withthe English language.

This book would not become a reality without the support of Visual Solutions,Inc., by allowing the book to be accompanied by a version of VisSim/Comm. Myspecial thanks goes to Mr. Jim Webb and Ms. Karen Darnell, Sales Managers, to Mr.Rich DiManno, from costumer support, and to Mr. Peter Darnell, President. Manythanks also go to Dr. Christoph Baumann, Engineering Editor of Springer-Verlag,for his constant support during the preparation of the manuscript.

I would like to thank Prof. Carlos Roberto dos Santos, Coordinator of the Elec-trical Engineering course at Inatel (Instituto Nacional de Telecomunicacoes), andto Prof. Jose Marcos Camara Brito, Coordinator of the Master degree course, forreducing my teaching activities during the last term before the end of the prepa-ration of the manuscript. Thanks also to Prof. Geraldo Gil Ramundo Gomes andProf. Luciano Leonel Mendes for substituting me in the teaching activities of agraduate course during that term, and to Prof. Marcelo Carneiro de Paiva for doingthe same in an undergraduate course. I am also indebted to Prof. Geraldo Gil forthe rich discussions about error-correcting codes and for the review of Chap. 8, andto Prof. Brito for reviewing Chap. 6. Thanks also to Prof. Estevan Marcelo Lopesfor reviewing Chap. 1, to Prof. Rausley Adriano Amaral de Souza for reviewingChap. 2, to Prof. Jose Antonio Justino Ribeiro for reviewing Chap. 3 and to Prof.Luciano Leonel Mendes for reviewing Chap. 7.

At last I would like to express my gratitude to the many contributors in the field ofDigital Communications, many of them referenced throughout this book, and fromwhom I have learned, and I am still learning a lot.

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Notes on the Accompanying CD with Softwareand Simulation Files

The accompanying CD contains three folders. The folder “VisSimComm” containsthe setup file for installing the simulation software VisSim/Comm 7.0 and the setupfile for installing the viewer-only version of the software. The folder “DAT” con-tains files that are necessary for some simulations to run. The folder “Simulations”contains all the simulation files used throughout the book. It is further divided intoeight sub-folders, each of them associated to one chapter of the book. To use thesupplied files, follow the instructions below.

• The simulation software VisSim/Comm 7.0 can be installed by running the file“setupVisSimCommWeb70.exe” inside the “VisSimComm” folder and followingthe instructions during the installation process. After installation VisSim/Commwill run in demo mode and will not let you save your work. However, you canrequest license keys to enable a 60-day trial that will let you save your implemen-tations. A trial license can be obtained via e-mail by running the “VisSim licensemanager”, which is automatically installed when you install VisSim/Comm, andclicking the “Email License Codes. . .” button. After receiving the reply with thetrial license keys, you must run the License Manager once more and insert thetrial license keys; your trial will run 60 days before requiring a permanent license.To purchase a permanent license, send an e-mail to [email protected]. For tech-nical questions, use [email protected].

• The simulation files supplied in the accompanying CD were implemented in away that you do not need a permanent license to run them. In fact, whether indemo mode or running VisSim/Comm Viewer you will not miss any simulationdetail explored throughout the book.

• After any of the working options of VisSim/Comm is installed and enabled, cre-ate the folder “C:\DAT” in your hard drive “C”. Copy the content of the DATfolder in the CD to the DAT folder you have just created. These DAT files arenecessary for some experiments to run and can not be created in another pathdifferent from “C:\DAT”, unless you modify all the corresponding file paths inthe simulation files.

• Before you start running the simulations, it is strongly recommended that youbecome familiar with the VisSim/Comm user interface. This can be easily

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accomplished through the VisSim/Comm documentation installed with the soft-ware in your computer.

Now you are ready to run the experiments located in the CD, in the folder “Sim-ulations”, according to the work plans supplied throughout the book. These workplans are identified by the word “Simulation” followed by its identification numberaccording to each chapter. As an example, Simulation 4.3 contains the guidelinesof the third simulation related to the fourth chapter. The header of each work plancontains information on which simulation file will be used.

This work was prepared with due care, trying to avoid or at least minimize errors.I apologize in advance for any mistake not detected during the reviewing process.However, I count on the reader to report any error found, directly to me or to thePublisher.

Good reading, good interaction with the simulation files and good learning.

Dayan Adionel Guimaraes

Author Disclaimer

The author and the publisher believe that the content of this book is correct. How-ever, all parties must rely upon their own judgment when making use of it. Neitherthe author nor the publisher assumes any liability to anyone for any loss or damagecaused by any error or omission in this book. The computer simulations in this bookhave been developed with the greatest of care to be useful to the readers in a broadrange of applications. However, they are provided without warranty that they andthe associated simulation software are free of errors.

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