Research On High-Performance Localization Algorithm In NLOS Environment Based On Scattering Information

Since Federal Communications Commission(FCC) released E911 standard, wireless localization technology has always been a research highlight. People have developed some algorithms that have high accuracy in Line-of-Sight(LOS) environment. But, in None-Line-of-Sight(NLOS) environment, signals transporting in air would have scattering and other problems, which make high accuracy localization in NLOS environment a big challenge that people have to face. Meanwhile, wireless localization in NLOS environment has been the focus of recent research of wireless localization since people have an urgent demand for high performance positioning algorithm in NLOS environment which is also the focus of this thesis. The main work of this thesis is as follows:At first, the global research status of NLOS wireless positioning technology is introduced based on the literature review in this thesis.Secondly, to solve the recognition problem about single path and multiple path of the scattering signals in NLOS propagation, this thesis presents a scattering path recognition algorithm based on Line-of-Possible-Mobile-Device(LPMD). Compared with the traditional algorithm, this algorithm considers the LPMD distribution characteristics of ordinary scenes and special scenes, to calculate the initial reference point position using all cross points of LPMD. And through to all intersections, new algorithm uses a part of the intersection that is most far away the initial reference point to do negative expectation of compensation about remaining intersections, which is in order to fix the position accuracy of the reference point. The simulation results also show that regardless of whether the target is in the measured area formed by the monitoring station, the accuracy of the reference point calculated by proposed algorithm have been significantly increased, and the false-alarm and miss-detect probability, also recognition rate were obviously improved.Then, to solve the problem that how to determine which single scattering paths are from the same scatter, this thesis proposes a same scattering point recognition algorithm based on LPMD. The algorithm uses scattering geometry information contained in LPMD line, to identify and classify these single scattering paths.The simulation results show that the algorithm has high recognition accuracy.Next, to solve the problem of wireless location in a pure NLOS environment, this thesis proposes a new algorithm,based on scattering path recognition algorithm on LPMD, using the intersection of LPMD from single scattering paths. The algorithm obtains the points which are more concentrated to the target by filtering on the single scattering paths of LPMD intersection, thus completing the positioning of the target point. The simulation results show that the algorithm has good performance and stability in the complex NLOS environment.Finally, the research work of this thesis is summarized and a prospect to the future work is provided.