Continuous and Discrete Phase-shifts for RIS-aided Systems in Wideband Communication Channels

This work investigates the performance of the reconfigurable intelligent surface (RIS) for wideband communication systems, also considering line of sight (LOS) channels. We evaluate the achievable rate of methods such as the alternating optimization (AO) and strongest tap maximization (STM), which are used to configure the RIS. Additionally, the impact of continuous and discrete phase-shifts is also analyzed in the context of novel proposed metrics, denoted as the relative and efficiency rate. It is demonstrated that discrete or quantized phase-shifts can achieve a rate close to that of continuous phase-shifts, if enough quantization bits are used.