Analysing and designing reliable and fast wireless networks requires an understanding of the theory underpinning these systems and the engineering complexities of their implementation. This text describes the underlying principles and major applications of high-speed wireless technologies, with emphasis on ultra-wideband (UWB) wireless systems, 3G long term evolution, and 4G mobile networks. Key topics such as cross-layer optimization are discussed in detail and various forms of UWB, including multi-band OFDM UWB, are covered. Recent research developments are described before identifying the scope and direction for future research. The overlay problem (interference problem) in UWB is discussed, and the author aims to illustrate that OFDM is not the best wireless access technique for high speed transmission. Covering the latest technologies in the area, this book will be a valuable resource for graduate students of electrical and computer engineering as well as practitioners in the wireless communications industry.