Ultra-wideband Communications System Positioning Technology

Recent years, Ultra wideband techniques have been the focus of much research and development because of its unique characteristics. Communication network based on UWB transmission has good abilities of low power consumption, potentially immunity to mutipath fading, anti-detection and high precision especially. Therefore, UWB technique is becoming a potential technique. Its application in military field and civilian field is becoming wider and wider, so the research of UWB positioning systems has great application values.In order to focus on the core problem of UWB location accuracy improvement, this thesis aims at TDOA location techniques, and investigates the following UWB network based location techniques: performance analysis of basic TDOA ranging algorithms, performance analysis of NLOS idenfitication and alleviation techniques and high accuracy TDOA location algorithms.Besides, the key techniques and relative problems of UWB network location are analyzed and discussed.This thesis analyzes the threshold selection algorithm based on energy detection which becomes a feasible alternative because of its simplicity and lower sampling rates.In this thesis, a delay-dependent threshold selection algorithm is introduced, the increase of the threshold values for smaller delays can significantly lower down the false alarm probability when the transmitter-to-receiver distance is relatively large. Simulation results show that this algorithm outperforms those existent algorithms.A statistical NLOS identification method based on the hypothesis-testing of received signal parameters in UWB propagation channels is discussed.The simulation results suggest that the RDS of UWB signals can be efficient indicator of the LOS and NLOS identification.The mathematical model of TDOA is established, the relationship between location error and the number of reference points, NLOS elimination, location algorithms are analyzed via simulation experiments.