The Research On Indoor DOA Positioning Based On Time Reversal

With the rapid development of mobile Internet and 5G and 6G technologies,positioning services based on precise locations have gradually become the focus of attention,and service requests for indoor positioning are also increasing.Direction of arrival(DOA)positioning technology,as a simple,low-cost positioning and easyimplementing method,has become one of the mainstream research methods for indoor positioning in recent years.However,the complex multipath environment existing in indoor positioning scenarios will greatly reduce the accuracy of the DOA positioning algorithm.How to reduce the positioning error caused by the multipath effect has become an urgent problem in the positioning research area.Time Reversal(TR)is a communication technology that can realize space-time synchronous focusing,which can effectively suppress multipath effects to reduce signal coherence,thereby improving the accuracy of positioning algorithm.Therefore,this article combines DOA positioning with TR technology to increase the accuracy of the positioning algorithm,and positioning research algorithms in two scenarios are proposed.The specific research content is as follows:First,in view of the problem that the indoor multipath effect seriously affects the DOA positioning accuracy,this thesis proposes an indoor DOA positioning algorithm based on TR to increase the positioning accuracy.Firstly,we establish the uniform linear array system model to detect the channel state information.On this basis,the received return signal is processed by TR technology and re-transmitted into the propagation medium space to obtain the key information of the target position.Finally,the eigenvalue subspace decomposition operation is performed and the DOA estimation value of the algorithm is obtained through one-dimensional spectral peak searching.The simulation results reveal that compared with the other algorithms,the proposed algorithm can effectively achieve the DOA estimation of the target with a lower root mean square error.Secondly,the antenna array will have a certain amplitude error or phase error in actual application scenarios,which makes it impossible for an inaccurately calibrated antenna array to accurately obtain a high-resolution DOA positioning value.To solve this problem,this article proposes a TR-based array amplitude and phase error auxiliary array element calibration algorithm.Firstly,use TR technology at the antenna array to suppress the multipath effect to reduce signal coherence.Secondly,use the instrumental sensor calibration method to derive the corresponding parameter and error expression,and effectively calibrate the signal with error.The simulation results confirm that the proposed algorithm can effectively calibrate the system error,and can maintain a resolution success rate of nearly 90% under the conditions of low signal-to-noise ratio and low number of shots.