Research On High Performance Localization Algorithm Based On Scatterer Identification In NLOS Environment

With the development of wireless communication technology and the popularization and application of the Internet of things in various industries,intelligent terminals and equipment are becoming more and more popular.Location-based service has become a necessary function of positioning and navigation,emergency search and rescue and disaster relief.In the process of wireless positioning,the positioning results are often disturbed by various influencing factors in varying degrees,among which non line of sight propagation is the main error source.In the sight distance environment,the accuracy of the existing positioning algorithms can reach centimeter level or even millimeter level.However,in real life,the environment is complex and changeable,and there may be obstacles in some positioning environments,which forms a non line of sight environment.The signal can only propagate through refraction or reflection,resulting in non-line-of-sight error and the decline of positioning accuracy.This thesis studies the path matching algorithm based on non-line-of-sight.The main work of this thesis is as follows:Firstly,by reading the literature,this thesis summarizes the research status of mobile station location algorithm based on scatterer in non-line-of-sight environment at home and abroad.The existing location algorithms in line-of-sight environment and various location accuracy evaluation indexes are studied.The time difference of arrival location algorithm is studied and analyzed in different environments.The simulation results show that the location accuracy of line-of-sight location algorithm will be greatly reduced in non-line-of-sight environment.Secondly,aiming at the problem of single scattering path recognition and matching from the same scatterer in non-line-of-sight environment,a new single scattering path recognition and matching algorithm based on line of possible mobile device is proposed.The algorithm locates the possible scatterers and mobile stations according to the angle of arrival measurements received by the base station,further determines whether the angle between the scatterer and the mobile station is consistent with the transmission angle of the signal,and completes the identification and matching of single scattering path.Simulation results show that the algorithm can effectively identify the matched single scattering path and has higher recognition performance.Thirdly,aiming at the problem of mobile station location in the severely occluded nonline-of-sight environment,the scatterer is used as a virtual base station to locate the mobile station.On the basis of identifying and matching the single scattering path passing through the same scatterer,the scatterer is located by using the improved data fusion location algorithm based on time difference of arrival / angle of arrival.Then,the scatterer with small distance error is regarded as a virtual base station,and the distance between the scatterer and the mobile station is regarded as the length corresponding to the time of arrival measurement in line-of-sight environment.The transformation from non line of sight location problem to line-of-sight location problem is realized.At the same time,the scenes with different number of virtual base stations are also studied.Simulation results show that the positioning accuracy of mobile station in non-line-of-sight environment is close to that in line-of-sight environment.Next,aiming at the location problem in indoor non-line-of-sight environment,an indoor non-line-of-sight single base station location algorithm based on scatterers is proposed.The algorithm locates the moving target according to the time of arrival measurement value,angle of arrival measurement value and the priori information of indoor structure in the indoor environment and non-line-of-sight propagation path.The algorithm is studied and analyzed by changing the relevant parameters in the indoor environment.Simulation results show that the algorithm can reduce the impact of non-line-of-sight error and has good positioning performance.Finally,a summary description of the work carried out in this thesis is presented and an outlook on the subsequent research content is given.