Weighted MSE Minimization for RIS-aided Multiuser MIMO OFDM Systems with ICSI

This work focuses on the downlink (DL) of a wideband reconfigurable intelligent surface (RIS)-aided multiuser (MU) multiple-input multiple-output (MIMO) system. Imperfect channel state information (ICSI) is considered and the statistics of channel estimation errors are leveraged for system design. To maximize the achievable rate, an alternating weighted mean square error (WMSE) minimization strategy is implemented to configure the RIS phase-shift matrix and the precoders/combiners. This approach is based on the broadcast (BC)-multiple access channel (MAC) duality and a projected gradient (PG) algorithm. Simulation results show significant performance gains over baselines and existing approaches.