Research On TDOA And AOA Positioning Technology Based On Beamforming

Since the United States FCC promulgated the specification of E-911 positioning requirements in the 1990 s,the research on positioning technology has aroused more and more attention.From the 1G to the 5G,each generation has researched on positioning technology.TDOA and AOA based 3D positioning technology in wireless positioning has been studied in this thesis.The main work are as follows:Firstly,the TDOA estimation method based on channel impulse response is studied.A channel estimation algorithm based on improved subspace pursuit algorithm is proposed,and the direct path is judged.Then the delay corresponding to the direct path is estimated as the time of arrival estimate.Since the subspace pursuit algorithm has certain requirements on the input,accurate sparsity prior information is required,and the sparsity is equal to the numbers of multipath.However,the numbers of multipath cannot be determined when the source signal is transmitted in the actual environment,so the sparsity cannot be accurately determined.The proposed improved subspace pursuit algorithm can solve the problem that the sparsity cannot be accurately determined,and then effectively estimate the channel.Using the sparse characteristics of the wireless channel,the channel impulse response estimated by the improved subspace tracking algorithm is beneficial to improve the TOA estimation accuracy.Secondly,for elevation AOA estimation,the existing one-dimensional AOA estimation algorithms are analyzed.Based on the MUSIC algorithm,an improved MUSIC algorithm based on beam space is proposed to estimate the elevation AOA between the serving base station and the UE.To the presence of coherent multipath signal,the autocorrelation matrix of the received signal is spread by the eigenvector,the rank of the signal subspace will be smaller than the actual number of the sources,the error of the estimation result is larger.The autocorrelation matrix of the received signal transforms into Toeplitz matrix is studied,and the Toeplitz matrix can solve the coherence problem.And then transforms the array element domain signal into the beam space domain using beamforming to achieve dimensionality and reduction to reduce computational complexity.The elevation of AOA can be estimated accurately using beamforming mechanism.Finally,using the angle information in the CIR estimated by the channel,the search area is further constrained to obtain an AOA estimate of the direct path.Finally,for the 3D positioning problem,a 3D positioning method based on the TDOA and elevation AOA is proposed,which uses three base stations to participate in positioning.Based on the traditional three-base station two-dimensional OTDOA positioning,the elevation AOA estimation information between the serving base station and the UE is increased.The height z coordinate of target UE is represented by the AOA estimation value and unknown x and y coordinates,the Fang and Taylor joint positioning algorithm is used to solve the x and y coordinates of the UE,and then the z coordinate is estimated,and finally the estimated position of the UE is obtained.