In the future of digital home networking, Ultra-Wideband (UWB) technology will be used as a wireless communication system to connect various devices like HDTVs, PCs, and Cell phones. One of the major challenges when designing UWB systems is the selection of the appropriate modulation scheme. Although M-ary Pulse Position Modulation (PPM) has better performance than M-ary Pulse Amplitude Modulation (PAM) for M2 in an UWB environment, it requires more accurate timing synchronization and has a higher computational complexity, particularly for large M. This book, therefore, provides a hybrid modulation scheme, called pulse amplitude position modulation (PAPM), which combines PPM and PAM constellations to provide a compromise between system performance and complexity. It contains concepts, modeling, capacity analysis of PAPM UWB System. The analysis of PAPM UWB should help understand other modulation schemes as the basic hybrid UWB system and should be useful to anyone else who may be considering utilizing UWB system with asynchronous multiple user interference.