MA辅助RIS-MIMO系统的信道模型分析及优化OA

In communication scenarios where line-of-sight links are absent,and the featuring rich scattering environment is rich,fixed antenna systems in reconfigurable intelligent surface(RIS)-aided multiple input multiple output(MIMO)communications face various challenges,such as channel gain degradation caused by severe multipath fading.To mitigate these multipath effects,this study converts both the base station(BS)antenna and the user equipment(UE)antenna into a movable antenna(MA)to improve the rank structure of the channel matrix and construct an MA-RIS-MIMO system tailored for rich scattering environments.First,the system is modeled,and the cascaded BS-RIS and RIS-UE channel models,as well as channel gain expressions,are derived for single-path,dual-path,triple-path,and multipath scenarios under known point-to-point channels.Then,based on these channel models,objective functions for system performance and rate are formulated,which optimize the BS and UE antenna positions,the RIS phase shift matrix,and BS transmit power.A fractional programming-based joint gradient ascent method is then applied to solve the optimization problem.Finally,simulation results demonstrate that the system utilizing MA at both BS and UE has a sum-rate gain of at least 6.4 bps/Hz compared with a fixed-position RIS-MIMO system,thereby validating the effectiveness of the established channel model for the proposed MA-RIS-MIMO framework.