Research On Indoor Localization Technology Based On Channel State Information

With the rapid development and prevalence of Internet,more and more location-based applications come to existence.These applications can utilize GPS or BeiDou to realize high precision positioning services in the outdoor environment.However,these systems will not work in an indoor environment due to the blocking of the signals,and LoS(Line of Sight)path will not exist.Many researches are based on WIFI devices and most of these researches utilize RSSI(Received Signal Strength Indicator).However the technology based on RSSI is difficult to achieve high precision in indoor environment.Some researchers utilize CSI(Channel State Information)to implement localization system.CSI is the fine-grained information of physical layer,it has high stability and low volatility of time,and more suitable for indoor localization.This thesis will explore how to utilize CSI to implement high precision localization in indoor environment.This thesis mainly studies several key technical problems and design some algorithms according to problems.The main research results of this thesis are summarized as follows:1.Analyze the phase error of Channel State Information and summarize the phase model.The thesis propose two methods to eliminate the phase error: phase processing method based on linear transformation and phase processing method based on multiple antennas.2.Analyze the Multiple Signal Classification(MUSIC)algorithm.The phase error will seriously affect the performance of MUSIC,so this thesis will combine MUSIC with phase model,and propose a new algorithm: MUSIC based on Phase Calibration(PC-MUSIC).Besides,this thesis also put forward the algorithm that remove the correction of CSI.3.The thesis utilize the AoA of LoS path and the propagation distance to define an objective function,and we can realize the localization by minimizing the objective function.4.The thesis use CDF method to evaluate the performance of our system.The experimental results show that the performance has been greatly enhanced.Besides,this thesis analyze some factors' influence on the performance of system.Finally,the thesis implement the indoor localization system based on the related algorithm.