Efficient Active Elements Selection Algorithm for Hybrid RIS-Assisted D2D Communication System

In this letter, we propose an efficient active elements selection (AES) algorithm for hybrid reconfigurable intelligent surface (RIS)-assisted device-to-device (D2D) communication system, where a subset of RIS elements is selected from the whole elements set to connect with power amplifiers (PAs), serving as the active RIS, while the others reflect the incident signals passively, serving as the passive RIS. A binary diagonal AES matrix is introduced to represent the connection relationship between the RIS elements and PAs. Then, we jointly design the D2D transmission power, AES matrix and RIS beamforming matrix to maximize the system sum rate. The corresponding simulation results have verified that the proposed algorithm outperforms the fixed scheme and is capable of compensating for the performance degradation caused by the decrease in the number of PAs.