Analysis and Comparison of Narrowband Channels With Different Phase Shifts in RIS-Aided Communication Systems

Recently, reconfigurable intelligent surface (RIS) is regarded as a potential technology in future communication networks, and design of RIS phase shift is important for performance and should be carefully considered in channel modeling of RIS-aided communications. However, most existing research works only use a discrete or continuous phase shift to investigate channel characteristics, lacking the comparison of different phases to provide specific guidance for RIS-aided communications. In this letter, a three-dimensional one-cylinder model is proposed for RIS narrowband channels. Based on the geometrical model, we focus on investigating how the model parameters affect channel statistical properties by adopting different time-varying RIS phases (angle-based phase and distance-based phase). The findings will provide guidance for RIS-aided network to establish intelligent, safe, and controllable propagation condition.