Robust Weighted Sum-Rate Maximization for Transmissive RIS Transmitter Enabled RSMA Networks

TL;DR

This paper introduces a novel RIS-based RSMA system for downlink multi-user communication, optimizing power, RIS coefficients, and user rates to maximize weighted sum-rate under partial CSI, using a BCD algorithm.

Contribution

It proposes a new transmissive RIS transmitter architecture with RSMA, addressing partial CSI and nonconvex optimization challenges with a novel BCD-based solution.

Findings

Transmissive RIS with RSMA outperforms SDMA and NOMA.

The proposed algorithm effectively optimizes the system performance.

Numerical results validate the advantages of the proposed architecture.

Abstract

Due to the low power consumption and low cost nature of transmissive reconfigurable intelligent surface (RIS),in this paper, we propose a downlink multi-user rate-splitting multiple access (RSMA) architecture based on the transmissive RIS transmitter, where the channel state information (CSI) is only accquired partially. We investigate the weighted sum-rate maximization problem by jointly optimizing the power, RIS transmissive coefficients and common rate allocated to each user. Due to the coupling of optimization variables, the problem is nonconvex, and it is difficult to directly obtain the optimal solution. Hence, a block coordinate descent (BCD) algorithm based on sample average approximation (SAA) and weighted minimum mean square error (WMMSE) is proposed to tackle it. Numerical results illustrate that the transmissive RIS transmitter with ratesplitting architecture has advantages over conventional space division multiple access (SDMA) and non-orthgonal multiple access (NOMA).