Reconfigurable Intelligent Surface Aided Massive MIMO Systems With Low-Resolution DACs

We investigate a reconfigurable intelligent surface (RIS)-aided multi-user massive multiple-input multi-output (MIMO) system where low-resolution digital-analog converters (DACs) are configured at the base station (BS) in order to reduce cost and power consumption. An approximate analytical expression for downlink achievable rate is derived based on maximum ratio transmission (MRT) additive quantization noise model (AQNM), maximization problem solved by particle swarm optimization (PSO) method under both continuous phase shifts (CPSs) discrete (DPSs) RIS. Simulation results show that sum tends constant with increase of number bits DACs, four enough capture large portion performance ideal perfect DACs case.