ulti-carrier modulation' Orthogonal Frequency Division Multi- Mplexing (OFDM) particularly' has been successfully applied to a wide variety of digital communications applications over the past several years. Although OFDM has been chosen as the physical layer standard for a diversity of important systems' the theory' algorithms' and implementation techniques remain subjects of current interest. This is clear from the high volume of papers appearing in technical journals and conferences. Multi-carrier modulation continues to evolve rapidly. It is hoped that this book will remain a valuable summary of the technology' p- viding an understanding of new advances as well as the present core technology. The Intended Audience This book is intended to be a concise summary of the present state of the art of the theory and practice of OFDM technology. The authors believe that the time is ripe for such a treatment. Particularly based on one of the author's long experience in development of wireless systems (AB), and the other's in wireline systems (BS)' we have - tempted to present a unified presentation of OFDM performance and xviii implementation over a wide variety of channels. It is hoped that this will prove valuable both to developers of such systems and to researchers and graduate students involved in analysis of digital communications.