Research On Indoor Pseudolite Signal Propagation Effect And Multipath Statistical Model

The application of pseudolite system in indoor positioning has the advantages of flexible networking,anti-interference,and compatibility with satellite navigation system.However,in complex indoor environment,the pseudolite signal is faced with power attenuation,multipath fading and other problems,which brings technical challenges to precise ranging and location information extraction.In this context,the disclosure of the propagation characteristics of indoor pseudolite signals and the establishment of multipath statistical model are of great significance to the signal recognition,extraction of receivers and the improvement of indoor positioning algorithm.This paper focuses on key issues such as complex multipath propagation characteristics and unknown fading statistical models when pseudolites are used for indoor positioning.Firstly,the propagation characteristics and application environment characteristics of indoor pseudolite signals are theoretically analyzed,and the multipath statistical model of indoor pseudolite signals is established.Secondly,based on the ray tracing algorithm,the multipath characteristic parameters of the pseudolite signal under three typical conditions are revealed.At the same time,the deterministic modeling method is proposed to estimate the parameters of the large-scale model of pseudolite signals,and the simulation results verify the correctness of the multipath statistical model.Finally,based on the autonomous pseudolite system and the experimental field,further actual verification of the parameter estimation effect of the large-scale model of the pseudolite signal,as well as the correctness and effectiveness of the multipath statistical model.The main work and contributions of the paper are as follows:1.Indoor pseudolite signal propagation characteristics analysis and multipath statistical modeling.According to the propagation characteristics of indoor wireless signals,the advantages and disadvantages of existing indoor channel models are compared and analyzed from the aspects of modeling methods and fading ranges.Based on the characteristics of the pseudolite signal system and the application environment,a multipath statistical model of indoor pseudolite signals is established based on the existing indoor channel model.Among them,large-scale fading is characterized by the logarithmic distance path loss model,and small-scale fading is described by the Rice,Rayleigh,and Lognormal distribution according to different environmental characteristics.2.Research on multipath characteristic parameters of pseudolite signals under typical conditions.Using the typical indoor spatial structure as the research object,the ray tracing method was used to study the propagation characteristics parameters of pseudolite signals at different indoor and outdoor launch points,different spatial complexity,and different number of wall penetration conditions,Including path loss,power delay,received power parameter characteristics.Simulation verification shows that when the outdoor pseudolite is used for indoor positioning,the number of effective multipath is less than 5,and the superimposed signal strength is difficult to reach the reception threshold of the receiving antenna;when the power attenuation is about 50 d B,the transmission distance of the non-line-of-sight and line-of-sight signals,13 m and more than 20 m in simple space scenes,9m and 20 m in moderately complex space scenes,and less than 5m and 17 m in complex space scenes;meanwhile,for the same transmission distance,the number of pseudolite signal through the wall increases by one,the path loss increase value is about 25 d B.3.Research on deterministic modeling method of pseudolite multipath signal.In order to realize the effective estimation of the parameters of the large-scale model of the pseudolite signal and verify the correctness of the multipath statistical model,a deterministic modeling method is proposed.The method includes scene classification modeling,multipath signal tracking extraction,and multipath parameter calculation.Carried out simulation calculations on typical scenarios such as parking lots,offices,shopping malls,etc.,and used the simulation results to estimate the attenuation factor of the pseudolite signal large-scale model.The results show that the estimated attenuation factors of parking lot,office,and shopping mall scenes are about 2.2,2.8,and2.9,respectively.At the same time,the statistically determined ray tracing deterministic model has good consistency with the statistical model,verifying the multipath statistical model correctness.4.Verification and validity of pseudolite multipath statistical model in actual scenarios.In order to verify the correctness of the large-scale model parameter estimation and multipath statistical model in the actual scene,an experimental building of CLP 54 was used as the actual test environment to compare and analyze the measured and theoretical values of the carrier-to-noise ratio of the pseudolite signal in the first floor(hall scene)and the second floor(office scene).The experimental results show that the maximum test error of the large-scale model in the hall scene and office scene is 4d B and 6d B,and the average test error is about 2.2d B and 3.2d B,which proves that the large-scale model attenuation factor estimation method has a good effect in actual scenes,and also shows that the log-distance path loss model can effectively characterize the large-scale fading process of pseudolite signals,and verifies the correctness and effectiveness of the multipath statistical model.