Preface
The second edition of this text has been written to initiate the newcomer to wireless personal communications, one of the fastest growing fields in the engineering world. Technical concepts which are at the core of design, implementation, research, and invention of wireless communication systems are presented in an order that is conducive to understanding general concepts, as well as those specific to current and evolving wireless communication systems and standards. This text is based upon my experiences as an educator, researcher, technical trainer, and consultant, and continues to be modeled from an academic course first developed for electrical engineering students in 1990, when there were fewer than five million cellular subscribers worldwide. As we begin the 21st century, more than 600 million people, about 10% of the world＇s population, pay a monthly subscription for wireless telephone service, and this figure will approach 50% by the end of the first decade of the 21st century.
    This text continues to evolve, and has been modified and updated since its first edition, making it a useful book for practicing engineers, as well as for researchers, graduate students, and undergraduate students. The text has been prepared to provide fundamental treatment about many practical and theoretical concepts that form the basis of wireless communications, and has been designed for easy but thorough treatment of vital material that all wireless practitioners must be comfortable with. I have tried to emphasize the technical concepts with worked example problems, and numerous, carefully crafted homework problems at the end of each chapter that are based on real-world industry issues. The second edition contains dozens of new homework problems and examples, as well as up-to-the minute technical details of the many emerging wireless standards throughout the world, making this book particularly useful for industry shortcourses or state-of-the-art academic classroom use.
References to journal articles are used liberally throughout this text to enable the interested reader to delve into additional reading that is always required to master any field. To support newcomers to the wireless field, and at the request of the Institute of Electrical and Electronics Engineers (IEEE), I have also prepared a low-cost two volume compendium of many of the originaljournal articles that first taught the fundamentals that are now used throughout the wireless industry-this compendium series is a useful, but not required, supplement to this text. Whether you intend to use this book for individual study, or for classroom use, or for use as a handbook, this text has been written as a complete, self-contained teaching and reference book. The numerous examples and problems found throughout the text have been provided to help the reader solidify the material.
     This book has been designed for the student or practicing engineer who is already familiar with technical concepts such as probability, communication theory, and basic electromagnetics. However, like the wireless communications industry itself, this book combines material from many different technical disciplines, so it is unlikely that any one person will have had introductory courses for all of the topics covered. To accommodate a wide range of backgrounds, important concepts throughout the text are developed from first principles, so that readers learn the foundations of wireless communications. This approach makes it possible to use this book as a handbook or as a useful teaching toolin a classroom setting.
The material and chapter sequence in this text have been adapted from an entry-level graduate course which I first taught in 1991 at the Virginia Polytechnic Institute and State University. Chapter 1 demonstrates the historic evolution of the wireless communications industry, and the evolution of wireless systems from first generation analog to second generation (2G) digital systems. Chapter 1 also documents the rapid early growth of cellular radio throughout the world and provides a state of the industry in the mid 1990s. Chapter 2 provides an overview of the major modern wireless communication systems of the 21st century, such as third generation (3G), Wireless Local Area Networks (WLANs), Local Multipoint Distribution Services (LMDS), and Bluetooth. Chapter 2 causes the reader to see how wireless networks are beginning to penetrate our daily lives for data and multimedia applications, as well as voice service. Chapter 3 covers fundamental cellular radio concepts such as frequency reuse and handoff, which are at the core of providing wireless communication service to subscribers on the move using limited radio spectrum. Chapter 3 also demonstrates the principal of trunking efficiency, and how trunking and interference issues between mobiles and base stations combine to affect the overall capacity of cellular systems. Chapter 4 presents radio propagation path loss, link-budgets, and log-normal shadowing, and describes different ways to model and predict the large-scale effects of radio propagation in many operating environments. Chapter 5 covers small-scale propagation effects such as fading, time delay spread, and Doppler spread, and describes how to measure and model the impact that signal bandwidth and motion have on the instantaneous received signal through the multipath channel. Radio wave propagation has historically been the most difficult problem to analyze and design for, since unlike a wired communication system which has a constant, stationary transmission channel (i.e., a wired path), radio channels are random and undergo shadowing and multipath fading, particularly when one of the terminalsis in motion. New material in Chapter 5 also teaches a fundamental and new way of modeling spatial-temporal channels, which is vital for the development of smart antennas and position location systems.
Chapter 6 provides extensive coverage of the most common analog and digital modulation techniques used in wireless communications and demonstrates tradeoffs that must be made in selecting a modulation method. Issues such as receiver complexity, modulation and demodulation implementation, bit error rate analysis for fading channels, and spectral occupancy are presented. Channel coding, adaptive equalization, and antenna diversity concepts are presented in Chapter 7. In portable radio systems where people communicate while walking or driving, these methods may be used individually or in tandem to improve the quality (that is, reduce the bit error rate) of digital mobile radio communications in the presence of fading and noise.
Chapter 7 introduces time, frequency, and code division multiple access, as well as more recent multiple access techniques such as packet reservation and space division multiple access. Chapter 7 also describes how each access method can accommodate a large number of mobile users and demonstrates how multiple access impacts capacity and the network infrastructure of a cellular system. Chapter 8 describes networking considerations for wide area wireless communication systems, and presents practical networking approaches that are in use or have been proposed for future wireless systems.
Appendices which cover trunking theory provide details for those interested in solving many practical wireless communications problems.The appendices also include hundreds of mathematical formulas and identities for general engineering work.  I have attempted to place numerous useful items in the appendices, so that this text may be easily used by students or practicing engineers to solve a wide range of problems that may be outside the scope of the immediate text.
For industry use,  Chapters 1-5 and 7 will benefit working engineers in the cellular/PCS system design and radio frequency (RF) deployment, operations, and maintenance areas. Chapters 1,2 and 6 are tailored for modem designers and digital signal processing (DSP) engineers new to wireless.  Chapters  1, 2 and 8 should have broad appeal to network operators and managers,  business and legal professionals, as well as working engineers.
To use this text at the undergraduate level, the instructor may wish to concentrate on Chapters 1-6, or Chapters 1-5, and 7, leaving the other chapters for treatment in a second semester undergraduate course or a graduate level course. Alternatively, traditional undergraduate courses on communications or network theory may find in Chapters 1, 2, 3, 4, 6, 7  and  8 useful material that can be inserted easily into the standard curriculum. In using this text at the graduate level,   I have been successful in covering most of the material in Chapters  1-6 and 8 during a standard half-year semester. In Chapters 2 and 8,I have attempted to cover important but rarely compiled information on practical network implementations and worldwide standards.
Without the help and ingenuity of several former graduate students, this text could not have been written. I am pleased to acknowledge the help and encouragement of Rias Muhamed, Varun Kapoor, Kevin Saldanha, and Anil Doradla-students I met in class while teaching an early version of the course Cellular Radio and Personal Communications, as well as my friend and former doctoral student, Greg Durgin. Kevin Saldanha also provided camera-ready copy for the first edition of this text (which turned out to be no small task!). The assistance of these students in compiling and editing materials for several chapters of this text was invaluable, and they were a source of constant encouragement throughout the project. Others who offered helpful suggestions, and whose research efforts are reflected in portions of this text, include Scott Seidel, Joe Liberti, Dwayne Hawbaker, Marty Feuerstein, Yingie Li, Ken Blackard, Victor Fung, Weifang Huang, Prabhakar Koushik, Orlando Landron, Francis Dominique, Greg Bump, and Bert Thoma. Zhigang Rong, Jeff Laster, Michael Buehrer, Keith Brafford, and Sandip Sandhu also provided useful suggestions and helpful reviews of early drafts. For the second edition, I also express my sincere gratitude to Hao Xu, Roger Skidmore, Paulo Cardieri, Greg Durgin, Kristen Funk, Ben Henty, Neal Patwari, and Aurelia Scharnhorst who have helped me greatly in preparing added material.
This text benefits greatly from practicalinput provided by severalindustry reviewers. Roman Zaputowycz of Bell Atlantic Mobile Systems, Mike Bamburak of McCaw Communications, David McKay of Ortel, Jihad Hermes of PrimeCo, Robert Rowe of Ariel Communications, William Gardner of Qualcomm, John Snapp of AT＆T Wireless, and Jim Durcan of Comcast Cellular provided extremely valuable input as to what materials were most important, and how they could best be presented for students and practicing engineers. Marty Feuerstein of Metawave and Mike Lord of Cellular One provided comprehensive reviews which have greatly improved the manuscript. Larry Sakayama of Agilent Technologies, Professor Philip DiPiazza of Florida Institute of Technology, and Jeff Stosser of Triplecom, Inc. provided valuable reviews of the new material in the second edition. The technical staff at Wireless Valley Communications, Inc. also provided feedback and practical suggestions during the development of this text.
From the academic perspective, a number of faculty in the wireless communications field provided useful suggestions which I readily incorporated. These reviewers include Prof. J. Keith Townsend of North Carolina State University, Prof. William H. Tranter of Virginia Tech, and Prof. Thomas Robertazzi of State University of New York. Professors Jeffrey Reed and Brian Woerner of Virginia Tech also provided excellent recommendations from a teaching perspective. I am grateful for the invaluable contributions from all of these individuals. Also, I wish to thank the numerous faculty, students, and practicing engineers from around the world, who continue to provide me with valuable feedback and suggestions, and who are using this book in their classrooms, short courses, and everyday work life.
I am pleased to acknowledge the support of the National Science Foundation, the Defense Advanced Research Projects Agency, and the many sponsors and friends who have supported my research and educational activities in wireless communications since 1988. It is from the excellent faculty at Purdue University, particularly my advisor, the late Clare D. McGillem, that I formally learned about communications and how to build a research program. I consider myself fortunate to have been one of the many graduate students who was stimulated to pursue a dual career in engineering and education upon graduation from Purdue.
Finally, it is a pleasure to acknowledge my family and students, as well as Bernard Goodwin of Prentice Hall, who commissioned this work and helped me bring this text to you.
                                                                  Theodore S. Rappaport