From the Back Cover

Excerpt. © Reprinted by permission. All rights reserved.

The rapid growth of wireless communications and its pervasive use in all walks of life are changing the way we communicate in some fundamental ways. Most important, reliance on radio propagation as the physical mechanism responsible for the transport of information-bearing signals from the transmitter to the receiver has endowed communications with a distinctive feature, namely, mobility.
Modern Wireless Communications is a new book aimed at the teaching of a course that could follow a traditional course on communication systems, as an integral part of an undergraduate program in electrical engineering or as the first graduate course on wireless communications. The primary focus of the book is on the physical layer, emphasizing the fundamentals of radio propagation and communication-theoretic aspects of multiple-access techniques. Many aspects of wireless communications are covered in an introductory level and book form for the first time.

1. ORGANIZATION OF THE BOOK

The book is organized in seven chapters, nine appendices, and a bibliography.
Chapter 1 motivates the study of wireless communications. It begins with a brief historical account of wireless communications, and then goes on to describe the OSI model of communication networks. The discussion, however, focuses on the issues that arise in the study of the physical layer, which is the mainstay of the book.
Chapter 2 on radio propagation starts with an explanation of the physical mechanisms of the propagation process, including free-space propagation, reflection, and diffraction. These physical mechanisms provide insight into the statistical models that are employed for terrestrial and indoor propagation effects that follow. The small-scale effects of fading and uncorrelated scattering are discussed, leading up to a careful classification of the different wireless channel types. The second half of the chapter describes noise and interference, and how combined with propagation, we may determine wireless communication system performance through a link-budget analysis.
Chapter 3 reviews the modulation process with emphasis on digital transmission techniques. This introductory treatment of modulation paves the way for discussions of the following issues:

• Complex baseband representation of linear modulated signals, and the corresponding input/output descriptions of linear wireless communication channels and linear band-pass filters.
• • Practical problems concerning adjacent channel interference and nonlinearities in transmit power amplifiers.

The stage is then set for comparative evaluation of various modulation strategies for wireless communications, discussion of receiver performance in the presence of channel noise and Rayleigh fading, and discussion of frequency-division multiple-access (FDMA).
Chapter 4 focuses on coding techniques and time-division multiple-access (TDMA). After a brief review of Shannon's classical information theory, the source coding of speech signals is discussed, which is then followed by fundamental aspects of convolutional codes, interleavers, and turbo codes. The relative merits of convolutional codes and turbo codes are discussed in the context of wireless communications. The various aspects of channel-estimation, tracking, and channel equalization are treated in detail. The discussion then moves onto TDMA and the advantages it offers over FDMA.
Chapter 5 discusses spread spectrum, code-division multiple-access (CDMA), and cellular systems. It first presents the basics of spread-spectrum systems, namely, direct-sequence, and frequency-hopped systems, and their tolerance to interference. A fundamental component of spread-spectrum systems is the spreading code: a section of the chapter is devoted to explaining Walsh-Hadamard, maximal-length sequences, Gold codes, and random sequences. This discussion is then followed with a description of RAKE receivers, channel estimation, code synchronization, and the multipath performance of direct-sequence systems. This leads naturally to a discussion of how direct-sequence systems perform in a cellular environment.
Chapter 6 is devoted to the notion of space diversity and related topics. It starts with diversity on receive, which represents the traditional technique for mitigating the fading problem that plagues wireless communications. Then the chapter introduces the powerful notion of multiple-input, multiple-output (MIMO) wireless communications, which includes space diversity on receive and space diversity on transmit as special cases. Most important, the use of MIMO communications represents the "spatial frontier" of wireless communications in that, for prescribed communication resources in the form of fixed transmit power and channel bandwidth, it provides the practical means for significant increases in the spectral efficiency of wireless communications at the expense of increased computational complexity. The discussion of MIMO wireless communications also includes orthogonal space-time block codes (STBC), best exemplified by the Alamouti code and its differential form. The discussion then moves onto space-division multiple access (SDMA), and smart antennas.
Chapter 7 links the physical layer and multiple-access topics of the previous chapters with the higher layers of the communications network. This final chapter of the book begins with a comparison of the different multiple-access strategies. The discussion then leads to a consideration of various link-management functions associated with wireless systems, namely, signaling, power control, and handover. The differences between systems used for telephony and those used for data transmission are clearly delineated. This is then followed by a discussion of wireless network architectures, both for telephony and data applications.

1.1 Theme Examples

An enriching feature of the book is the inclusion of Theme Examples within each of the chapters in the book, except for Chapter 1. In a loose sense, they may be viewed as "Chapters within Chapters" that show the practical applications of the topics discussed in the pertinent chapters. Specifically, the following Theme Examples are discussed:
Chapter 2: Empirical propagation model, wireless local area networks (LANs), and impulse radio and ultra-wideband
Chapter 4: Global system for mobile (GSM) communications, joint equalization and decoding, and random-access techniques
Chapter 5: Code-division multiple access (CDMA) Standard IS-95, GPSS, bluetooth, wideband CDMA and WiFi
Chapter 6: BLAST architectures, diversity, space-time block codes, and V-BLAST, and keyhole channels
Chapter 7: Wireless telephone network standards, wireless data network standards, and IEEE 801.11 MAC

1.2 Appendices

To provide supplementary material for the book, nine appendices are included:

• Fourier theory
• Bessel functions
• Random variables and random processes
• Matched filters
• Error function
• Maximum a posteriori probability (MAP) decoding
• Capacity of MIMO links
• Eigendecomposition
• Adaptive antenna array

The inclusion of these appendices is intended to make the book essentially self-sufficient.

1.3 Other Features of the Book

Each chapter includes "within-text" problems that are intended to help the reader develop an improved understanding of the issues being discussed in the text. "End-of-chapter" problems provide an abundance of additional problems, whose solutions will further help the reader develop a deeper understanding of the material covered in the pertinent chapter.
Moreover, each chapter includes examples with detailed solutions covering different aspects of the subject matter.
"Notes and References" included at the end of the chapter provide explanatory notes, and they guide the reader to related references for further reading. All the references so made are assembled in the Bibliography placed at the end of the book.

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