Research On Hybrid Localization Algorithm Based On TOA/AOA For Mitigating Non-Line-of-Sight Error

With the high-speed development of mobile communication technology and the popularity of smart phones, the location based service industry has become a new market outbreak after the Internet industry both domestic and overseas. Under this background, wireless location technology has been paid extensive attention to major companies and research institutes. But in the process of the actual location, the Non Line of Sight(NLOS) transmission always have a great impact on the positioning accuracy, this thesis mainly studies how to use TOA/AOA hybrid positioning technology to mitigate the NLOS error.Firstly, the civil and international research status of wireless positioning technology is introduced. The basic principle of the wireless location and the corresponding parameters’ measuring methods are expounded. At the same time, the positioning technology of 2G, 3G, 4G are discussed, and several factors affecting the positioning accuracy are analyzed.Secondly, two kinds of commonly used scattering models under NLOS environment, ROS model and DOS model, are studied. The methods of mitigating NLOS error are discussed in two aspects: NLOS identification and suppression. At the same time, the performance simulation and analysis of several classical TOA/AOA hybrid positioning algorithms are carried out.Thirdly, aiming at the drawback that traditional linear location algorithm has poor positioning accuracy in NLOS environment, by adding positioning line and using weighted average method, not only the positioning accuracy is improved, but also the advantage of low computational complexity is retained. In single-bounced circle model, aiming at the problem that GSA location algorithm is seriously time-consuming, through the virtual base station and maximum scatter radius, search scope and search time are reduced; the weighted average method is used in data processing to improve the positioning accuracy. Meanwhile, aiming at the issues that the traditional location algorithms always need more base stations in process of actual location and the ability of anti-NLOS error is weak, a hybrid location algorithm of single base station based on Multiple-Input-Multiple-Output(MIMO) system is proposed. By using signal paths’ parameters and geometrical relationship of base station, mobile station and scatters, the position of mobile station is estimated. Simulation results show that these TOA/AOA hybrid location algorithms can effectively improve the positioning accuracy in NLOS environment.Finally, the work of this thesis is summarized, and the development of cellular wireless location is prospected.