RIS Channel Decoupling Based on Decomposition of Receiving and Transmission Matrix Components of RIS Regulation Matrix

In this letter, a novel reconfigurable intelligent surface (RIS) channel decoupling based on a decomposition of receiving and transmitting matrix components of RIS regulation matrix is proposed to simplify the calculation of RIS beamforming matrix. The idea is to decompose an RIS regulation matrix into a receiving matrix and a transmitting matrix. Thus, the decoupling of RIS cascaded channels is realized for the calculation of the regulation matrix. Furthermore, the single UE and multi-UE scenarios are discussed respectively, and the corresponding solutions are given. The proposed schemes are simulated and validated. The numerical simulation results indicate that the simplified algorithm based on channel decoupling can achieve the expected performance.