基于可移动单元的智能反射面辅助近场定位技术OA

Reconfigurable intelligent surface(RIS)has broad prospects in enhancing the reliability of perception systems.Meanwhile,movable antenna can dynamically change the position of antennas at the transmitter and/or receiver by leveraging the local movement of antennas for optimizing channel conditions and improving communication performance.Therefore,combining movable antenna with RIS can fully exploits the spatial variations of the wireless channel in a limited area to further realize an intelligent and controllable wireless channel propagation environment.Therefore,a near-field localization technique based on RIS with movable elements is investigated.Firstly,a maximum likelihood positioning algorithm is proposed with a near-field model,and the Cramér-Rao lower bound(CRLB)is derived to characterize the localization performance.Then,an alternating optimization algorithm based on projected gradient descent is proposed to achieve joint optimization of the dynamic positions and beamforming of RIS,and thus an optimized structure and phase configuration for RIS are obtained for localization.Simulation results show that,compared to traditional fixed RIS,flexible topology adjustment of RIS reflecting units can obtain better channel conditions,which significantly reduces the CRLB of the user position estimation and improves system localization performance.