Two-Timescale Design for Reconfigurable Intelligent Surface-aided Full-Duplex Massive MIMO Systems

In this paper, we aim to investigate a full-duplex reconfigurable intelligent surface (RIS)-aided massive multiple-input multiple- output (mMIMO) system. Different from the existing contributions, we consider the two-timescale design scheme. Specifically, the phase shift at the RIS is designed based on the statistical channel state information (CSI), while the beamforming at the base station (BS) is designed based on the instantaneous effective CSI. We derive the closed-form expression of the uplink (UL) and downlink (DL) achievable rate, analyse the system performance and use genetic algorithm (GA) to maximize UL, DL and full-duplex achievable sum rate.