Research And Implementation Of Mobile Terminal Rapid Positioning Method Based On Adaptive Antenna Array

In recent years,with the rapid development and large-scale application of mobile communication technology,the number of mobile communication terminals has soared.In order to meet the needs of operators to provide LBS and public security,fast and accurate positioning of mobile terminals has always been one of the key technical directions for research and application.With the continuous development of array signal processing technology,the positioning technology based on adaptive antenna arrays is more and more widely used.This paper mainly studies the algorithm and technology of fast and accurate location of mobile terminal based on LTE uplink channel DMRS sequence and adaptive antenna array.To begin with,this thesis analyzes the adaptive antenna array and the basic theory of thirdparty positioning of mobile terminals.This paper briefly introduces two problems in DOA estimation of mobile terminal by the third party,which are,the same frequency interference existing in the adjacent cell users,and the asynchronous arrival of the target user and the interfering user.Then,two classical algorithms for DOA non-blind estimation are described in detail: fixed-step LMS algorithm and RLS algorithm,and the basic principles of several variable step LMS algorithms are briefly introduced.A new multi-parameter variable step LMS algorithm is proposed based on the characteristics of Sigmoid function and log function.The performance of several LMS algorithms in an adaptive filter system with order two is compared through simulation experiments.The convergence of the algorithm is tested.Then the nature of the LTE uplink reference signal DMRS is studied.Aiming at the LTE uplink DMRS sequence transmission model of mobile terminal,the reception model of thirdparty equipment is constructed,and the implementation method of DOA non-blind estimation in third parties is deduced theoretically.The autocorrelation and cross-correlation properties of the DMRS sequence are applied to obtain the energy spectrum of the received signal.According to the position of the energy spectrum peak,we extract the sequence segment where the target source DMRS is located,and then use the proposed new variable step size LMS algorithm to conduct DOA estimation,before drawing a comparison and discussion with the traditional MUSIC algorithm,fixed step LMS,and logarithmic function based variable step size LMS algorithm.Finally,the DOA non-blind estimation algorithm based on LTE system was transplanted into C++ language and implemented on the Visual Studio platform.The data generated by Matlab was used to verify the algorithm after transplantation.Meanwhile,the resource cost of the program after transplantation was estimated to verify the feasibility of transplantation.