Fast Precoding Scheme for Reconfigurable Intelligent Surfaces

Precoding is one of the challenges for the Reconfigurable Intelligent Surfaces (RIS)-assisted wireless communication system. The generally large RIS array and huge number of units lead to the high precoding complexity and feedback overhead. In this paper, a discrete Fourier transform (DFT) codebook-based multi-user precoding scheme is proposed to reduce the complexity and feedback overhead of precoding. To improve the precoding performance of multiple users, a user pairing strategy is introduced before transmission to ensure that there is a certain degree of orthogonality of the channels between users who are transmitting at the same time. The performance of the proposed scheme is verified by simulation experiments.