Today in the field of data communication,the demand for high transmission rate and diversified business is on the rise, while the spectrum resources are increasingly scarce, transmitting power is also limited. The contradiction between resources and demand is increasingly evident. Ultra-Wideband (UWB) communication systems employ ultra-short impulses to transmit information which spreads the signal energy over a very wide frequency spectrum of several GHz. It has become a hot topic in data communication, and plays a more and more important role in the field of Wireless Local Area Network (WLAN) and Wireless Personal Area Network(WPAN).In this paper, the theory of Ultra wide band wireless communication technologies is introduced. At the beginning of the paper, it studies UWB pulse waveform and modulation technologies, spread spectrum communication technology that UWB employed is also introduced. General indoor channel models (Δ? Kmodel,S-V model and the indoor channel models of IEEE 802...更多.15.3a proposal etc.) are studied, a suitable indoor channel model are proposed for the error performance and capacity analysis of TH-PPM UWB system. The error probability and capacity of TH-PPM (Time-Hopping pulse position modulation) UWB system are investigated. We consider PPM over additive white Gaussian channels for a single-user system. A multiuser environment with PPM is also investigated. The simulation analysis for TH-PPM UWB system over indoor fading channels is considered. At the last part of the paper, how to improve the performance and capacity is discussed. We consider two approaches ,one is the improvement on pulse position modulation. bi-orthogonal PPM and Non-orthogonal PPM over AWGN channel is investigated; the other way is about Rake receiver. The model of Rake receiver is introduced.
