Expert Report of John Proakis, PhD

PREFACE

The fourth edition of Digital Communications has undergone a minor revision. Several new topics have been added, including serial and parallel concatenated codes, punctured convolutional codes, turbo TCM and turbo equalization, and spatial multiplexing. Since this is an introductory-level text, the treatment of these topics is limited in scope.

The book is designed to serve as a text for a first-year graduate-level course for students in electrical engineering. It is also designed to serve as a text for self-study and as a reference book for the practicing engineer involved in the design of digital communications systems. As a background, I presume that the reader has a thorough understanding of basic calculus and elementary linear systems theory and some prior knowledge of probability and stochastic processes.

Chapter 1 is an introduction to the subject, including a historical perspective and a description of channel characteristics and channel models.

Chapter 2 contains a review of the basic elements of probability and stochastic processes. It deals with a number of probability distribution functions and moments that are used throughout the book. It also includes the derivation of the Chernoff bound, which is useful in obtaining bounds on the performance of digital communications systems.

Chapter 3 treats source coding for discrete and analog sources. Emphasis is placed on scalar and vector quantization In Chapter 4, the reader is introduced to the representation of digitally modulated signals and to the characterization of narrowband signals and systems. Also treated in this chapter are the spectral characteristics of digitally modulated signals. New material has been added on a linear representation of CPM signals.

Chapter 5 treats the design of modulation and optimum demodulation and detection methods for digital communications over an additive white Gaussian noise channel. Emphasis is placed on the evaluation of the error rate performance for the various digital signaling techniques and on the channel bandwidth requirements of the corresponding signals.

Chapter 6 is devoted to carrier phase estimation and time synchronization methods based on the maximum-likelihood criterion. Both decision-directed and non-decision-directed methods are described.

Chapter 7 treats the topics of channel capacity for several different channel models and random coding.

Chapter 8 treats linear block and convolutional codes. The new topics added to the chapter include serial and parallel interleaved concatenated block and colvolutional codes, punctured and rate-compatible convolutional codes, the soft-output Viterbi algorithm (SOVA), and turbo TCM.

Chapter 9 is focused on signal design for bandlimited channels. This chapter includes the topics of partial response signals and run-length-limited codes for spectral shaping.

Chapter 10 treats the problem of demodulation and detection of signals corrupted by intersymbol interference. The emphasis is on optimum and suboptimum equalization methods and their performance. New topics added to the chapter include Tomlinson-Harashima precoding, reduced complexity maximum-likelihood detectors, and turbo equalization.

Chapter 11 treats adaptive channel equalization. The LMS and recursive least-squares algorithms are described, together with their performance characteristics. This chapter also includes a treatment of blind equalization algorithms. New topics added include the tap-leakage algorithm and methods for accelerating the initial convergence of the LMS algorithm.

Chapter 12 treats multichannel and multicarrier modulation. The latter subject is particularly appropriate in view of several important applications that have been developed over the past two decades.

Chapter 13 is devoted to spread spectrum signals and systems. The benefits of coding in the design of spread spectrum signals is emphasized throughout this chapter.

Chapter 14 treats communication through fading channels. Several channel fading statistical models are considered, with emphasis placed on Rayleigh fading and Nakagami fading. Trellis coding for fading channels is also included in this chapter. New material added includes a brief treatment of fading and multipath characteristics of mobile radio channels, receiver structures for fading multipath channels with intersymbol interference, and spatial multiplexing using multiple transmit and receive antennas.

Chapter 15 treats multiuser communications. The emphasis is on code-division multiple access (CDMA), signal detection and random access methods, such as ALOHA and carrier-sense multiple access (CSMA).

With 15 chapters and a variety of topics, the instructor has the flexibility to design either a one-or two-semester course. Chapters 3-6 provide a basic treatment of digital modulation/demodulation and detection methods. Channel coding, treated in Chapters 7 and 8, can be included along with modulation and demodulation in a one-semester course. The topics of channel equalization, fading channels, spread spectrum, and multiuser communications can be covered in a second-semester course.

Throughout my professional career, I have had the opportunity to work with and learn from a number of people whom I should like to publicly acknowledge. These include Dr. R. Price, P.R. Drouilhet, Jr., and Dr. P.E. Green, Jr., who introduced me to various aspects of digital communications through fading multipath channels and multichannel signal transmission during my employment at the MIT Lincoln Laboratory. I am also indebted to Professor D.W. Tufts, who supervised my Ph.D. dissertation at Harvrd University and who introduced me to the problems of signal design and equalization for band-limited channels. Over the years, I have had the pleasure of working on a variety of research projects in collaboration with colleagues at GTE and Stein Associates, including Dr. S. Stein, Dr. B. Barrow, Dr. A.A. Giordano, Dr. A.H. Levesque, Dr. R. Greenspan, Dr. D. Freeman, P.H.Anderson, D. Gooding, and J. Lindholm. At Northeastern University, I have had the benefit of collaborating with Dr. M. Salehi, Dr. M. Stojanovic and Dr. D. Brady. Dr. T. Schonhoff provided the graphs illustrating the spectral characteristics of CPFSK, and H. Gibbons provided the data for the graphs in Chapter 14 that show the performance of PSK and DPSK with diversity. The assistance of these colleagues is greatly appreciated.

McGraw-Hill and I would like to thank the reviewers of this edition for their valuable suggestions. (Names?)

Finally, I wish to express my appreciation to Gloria Doukakis, for typing the manuscript of this edition.

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