Hybrid Precoding Design for Reconfigurable Intelligent Surface aided mmWave Communication Systems

TL;DR

This paper proposes a joint hybrid precoding and phase shift optimization method for RIS-assisted mmWave multi-user systems, improving signal accuracy with a proven convergent gradient-projection algorithm.

Contribution

It introduces a novel joint design approach for hybrid precoding and RIS phase shifts using gradient projection, with proven convergence and enhanced performance.

Findings

Significant MSE reduction demonstrated in simulations

Proposed algorithm converges reliably

Performance gain over existing methods

Abstract

In this letter, we focus on the hybrid precoding (HP) design for the reconfigurable intelligent surface (RIS) aided multi-user (MU) millimeter wave (mmWave) communication systems. Specifically, we aim to minimize the mean-squared-error (MSE) between the received symbols and the transmitted symbols by jointly optimizing the analog-digital HP at the base-station (BS) and the phase shifts (PSs) at the RIS, where the non-convex element-wise constant-modulus constraints for the analog precoding and the PSs are tackled by resorting to the gradient-projection (GP) method. We analytically prove the convergence of the proposed algorithm and demonstrate the desirable performance gain for the proposed design through numerical results.