This book serves as an easily accessible reference for wireless digital communication systems. Topics are presented with simple but non-trivial examples and then elaborated with their variations and sophistications. The book includes numerous examples and exercises to illustrate key points. For this new edition, a set of problems at the end of each chapter is added, for a total of 298 problems. The book emphasizes both practical problem solving and a thorough understanding of fundamentals, aiming to realize the complementary relationship between practice and theory. Though the author emphasizes wireless radio channels, the fundamentals that are covered here are useful to different channels - digital subscriber line, coax, power lines, optical fibers, and even Gigabit serial connections. The material in chapters 5 (OFDM), 6 (Channel coding), 7 (Synchronization), and 8 (Transceivers) contains new and updated information, not explicitly available in typical textbooks, and useful in practice. For example, in chapter 5, all known orthogonal frequency division multiplex signals are derived from its digitized analog FDM counterparts. Thus, it is flexible to have different pulse shape for subcarriers, and it can be serial transmission as well as block transmission. Currently predominant cyclic prefix based OFDM is a block transmission using rectangular pulse in time domain. This flexibility may be useful in certain applications. For additional information, consult the book support website: https://baycorewireless.com