Research On Multipath Estimation And Suppression Techniques In TC-OFDM Indoor Location Systems

With the development of mobile internet technology,Location Based Services(LBS)has received widespread attention.The demand for location services based on indoor scenes is also increasing,and there are further requirements for the accuracy of positioning technology.The TCOFDM(Time&Code Division Orthogonal Frequency Division Multiplexing)positioning system proposed by Beijing University of Posts and Telecommunications utilizes the integrated fusion of positioning and communication signals to achieve high-precision wide area indoor and outdoor seamless positioning.In typical indoor space scenarios such as large buildings and indoor corridors,TC-OFDM positioning systems face challenges such as code loop phase discrimination errors and reduced positioning accuracy caused by indoor multipath interference.This article proposes a multipath suppression technology based on indoor multipath estimation at the level of tracking loop and positioning calculation in the TC-OFDM indoor positioning system,which addresses the problems of large phase discrimination error and low positioning calculation accuracy in the tracking loop of the tracking receiver in indoor multipath rich environments.The improved algorithm in this article was simulated on a simulation platform,and a positioning receiver hardware platform based on ARM+FPGA was ultimately built to complete algorithm performance testing.The simulation and test results show that the improved algorithm in this paper can reduce the phase discrimination error of the tracking loop caused by indoor multipath interference by 32%,the TDOA chip error collected by the receiver by 25%,and the positioning calculation error by 21%.The main research content of this article is as follows:1.Introduced the impact of multipath interference in indoor space on the receiver code loop.Analyzed the theory of indoor spatial ray propagation,established a model for the propagation process of multipath interference in indoor scenes,and proposed a multipath estimation algorithm suitable for TC-OFDM indoor positioning systems.Introduced traditional multipath suppression techniques and analyzed their advantages and disadvantages,and finally proposed an ELS algorithm based on indoor multipath estimation.2.Introduced the principle of traditional Kalman filtering algorithm and the optimal linear smoothing algorithm based on this,and then analyzed and proposed the optimal linear smoothing filtering algorithm based on indoor multipath estimation.Introduced the traditional residual weighted positioning algorithm,and further improved the indoor multipath estimation combined positioning algorithm based on TDOA fusion.3.Introduced the software and hardware architecture of TC-OFDM indoor positioning receiver,and designed corresponding baseband hardware modules based on the algorithm in this paper.Build an actual testing environment,conduct performance testing on the algorithm proposed in this article,and analyze the test results.