Research On Nlos Environmental Location Technology Based On Single/Multiple Scattering Path Identification

With the rapid development of mobile communication technology,social life is becoming more and more intelligent and convenient.Meanwhile,existing technologies and services need to be constantly updated and improved.As a basic and important service,positioning service is always providing convenience to people’s life.The provision of positioning service cannot be separated from the support of mobile terminal precise positioning technology.For this reason,various positioning technologies based on mobile terminals have received extensive attention and research.At present,the existing positioning algorithms can achieve good positioning performance in the LOS propagation environment;however,there are still many challenges to achieve accurate positioning of mobile terminals in the NLOS environment.Therefore,this thesis focuses on the problem of mobile station location under NLOS propagation environment and studies the single/multiple scattering path identification problems.The main tasks of this thesis are as follows:Firstly,a large number of related literatures were searched and read.The positioning algorithm using scatters in wireless positioning technology is summarized into two categories.One is the algorithm based on the scatter model,and the other is the algorithm based on the geometric relationship between the scatter and the mobile station.But the most of algorithms assume that there are only single scattering paths and no multiple scattering paths.This thesis studies and discusses the recognition problem of single/multiple scattering paths.And the positioning performance of two classical localization algorithms under different scattering models is analyzed.Secondly,aiming at the problem of NLOS environment position without direct path,this thesis analyzes a TOA/AOA hybrid position algorithm based on the position relationship of each node,based on it,an improved algorithm is proposed.The algorithm first estimates the position of the mobile station,and then uses the nonlinear optimization method to perform the second-order optimization on the initial estimate to obtain a positioning result closer to the true position.The simulation results show that the positioning error of the improved algorithm is obviously reduced and it has better positioning performance.Next,the identification of single/multiple scattering paths in NLOS environment is studied,and an improved recognition algorithm based on possible position lines of mobile stations is proposed.The algorithm makes full use of each scattering path,calculates the intermediate reference point by the residual weighting method,weakens the influence of multiple scattering paths,and then calculates the distance from the intermediate referencepoint to each possible position line,after that the distance weight corresponding to each distance is calculated,then the single/multiple scattering path is identified and judged through the threshold.The simulation results show that the improved recognition algorithm can obtain more accurate reference points and the correct path recognition rate is also improved.Then,aiming at the location problem of single scatters and mobile stations,a scatter position algorithm based on multi-antenna array is analyzed and studied.Using this algorithm,the position of the scatter is solved,and then the scatter is used as a “virtual base station” to implement LOS positioning for the mobile station.Simulation results show that this method can effectively weaken the positioning error caused by NLOS.Finally,this article summarizes the work that has been carried out and looks ahead to the follow-up work.