Optimal Size and Quantization Phase Control Resolution Study of Reconfigurable Intelligent Surface for 6G Wireless Communication System

This paper presents reconfigurable intelligent surface (RIS) design guidelines for improving none-line-of-sight (NLOS) link performance. Based on the path loss model, the optimal number of unit cells with the distance away from RIS and the corresponding number of phase control bits are derived. The system model used to obtain simulation results have been verified through comparison with 3D EM full simulation, and various RIS-aided wireless communication environments can be analyzed. The power received by users was calculated by increasing the number of unit cells of RIS at a fixed distance. Even if the size of the RIS increases, the point at which the received power does not increase by more than 10% is defined as the point at which the received power is saturated, that is, the optimal size at the corresponding distance. The optimal size varies according to the distance between the RIS and the user and does not vary significantly with respect to the steering angle. Quantization phase control resolution was calculated through comparison with received power when the reflection coefficient of RIS can be continuously adjusted. A RIS having an optimal size at a given distance can receive more than 80% of the power compared to a continuous control if 2-bit or more phase control is possible.