Research On The Application Of TDOA/AOA Combined Positioning Technology In Urban Canyons

With the acceleration of China's urbanization process and the continuous improvement of economic living standards,on the one hand,the phenomenon of urban canyons formed by highrise buildings and dense streets is becoming increasingly obvious,and the GNSS-based satellite positioning signal is blocked and reflected by dense buildings,which will cause the positioning error to be as high as 100 meters or even unable to locate;on the other hand,people's demand for location based services(Location Based Services,LBS)continues to increase.Traditional low-precision positioning techniques are difficult to meet.Therefore,this paper is committed to the study of a high-precision positioning technology based on 5G network to overcome the problem of GNSS positioning failure in urban canyons.The main research contents of this paper are as follows:1.The research analyzes a variety of estimation algorithms based on Angle of Arrival(AOA),and an improved MVDR algorithm in 5G environment is proposed.Firstly,the characteristics of AOA estimation based on two classical beamforming algorithms under uniform linear array are analyzed;secondly,an improved MVDR algorithm is proposed,which combines the multipath effect existing in the urban canyon environment and introduces a variable loading factor To process the array signal to achieve the purpose of enhancing the desired signal,reducing the interference,and then obtaining a more accurate angle of arrival estimation;finally,combined with the large-scale antenna array technology of 5G,the AOA estimation of the improved MVDR algorithm is extended to a uniform plane array.In the threedimensional space,a more accurate pitch angle and azimuth angle are obtained,and the simulation test verifies the effectiveness of the improved algorithm in this paper.2.The research analyzes a variety of estimation algorithms based on Time Difference of Arrival(TDOA),and a TDOA estimation algorithm combining spectral correlation correction method and DATEMM is proposed.Firstly,the spectral correlation correction method uses the cyclostationary characteristics of the signal to process the signal to achieve the suppression of noise and interference;secondly,for the multipath effect of urban canyons,the DATEMM algorithm uses the information of the autocorrelation function to extract from the multiple peaks of the cross-correlation function.The real TDOA value is extracted to weaken the influence of multipath on TDOA estimation.Finally,the simulation test verifies the effectiveness of the method.3.Taking the coverage area of three 5G macro base stations as the test environment,the three-dimensional TDOA/AOA combined positioning scheme is proposed for the urban canyon,and the solution of the TDOA hyperbolic positioning equation is participated in by introducing the pitch angle estimate of AOA,and the Chan algorithm and the Taylor iterative algorithm are used to analyze the user position estimate so that it is close to the true value.4.The program development environment based on MATLAB software is selected,and the TDOA/AOA combined positioning method is used to test the positioning accuracy and robustness of this method in urban canyons by taking the network in various urban environments as the object.