Technology-based Tr Ultra-wideband Wireless Communications Technology

The time variety and multi-path effect of channel environment, which most users of ultra-wideband communication systems have, could extremely degrade the transmission performance. A promising solution to this problem is to employ the environment adaptive technique in the transmission link. Recently, many reports in time reversal research indicated the notable characteristic of time reversal, named space-time focusing. The combination of time reversal technology with ultra-wideband technology is believed having great potential applications.The target of this thesis is to appropriately use the time reversal technique in the ultra wideband wireless communication system, concretely, to establish the model of time reversal based UWB system, to discuss the communication performance, and to investigate the system performanece improvement brought in by the time reversal technique.The content of the thesis is presented as follows.Firstly, the basic theory of time reversal based UWB wireless communication system is introduced and the elements of the system are described in detail. Then the time hopping pulse position modulation (TH-PPM) UWB system model and direct sequence pulse amplitude modulation (DS-PAM) UWB system model are established.Secondly, the TH-PPM-UWB system model based on time reversal and DS-PAM-UWB system model based on time reversal are developed on the platform of Matlab and Simulink. Some of the M files for key mudules are analyzed in detail.At last, the two impulse-based UWB systems based on time reversal technique and the ordinary UWB system using Rake receiver in AWGN channel and IEEE multi-path channels are simulated. The research on the improvement of communication performance and system structure are discussed by comparison and analyzation.