A modified joint decoding scheme for RSMA-aided downlink

Abstract

Rate splitting multiple access (RSMA) is envisioned as a promising next generation mobile communication. Numerous studies have demonstrated the superior performance of RSMA over conventional multiple access due to its powerful interference management strategy and flexible multi-user management. However, a potential issue of decoding at the receiver is ignored due to its unplanned power allocation to multi-user, which leads to a substantial reduction in outage performance and additional energy consumption. To overcome the above issues, in this paper, a novel joint decoding design for the RSMA is investigated to improve the overall performance in terms of outage probability and energy consumption. The focus of the investigation is to decode common and private messages at the receiver, providing the suboptimal power allocation to enhance decoding accuracy and reduce energy consumption. Unlike conventional RSMA decoding schemes, the common message and corresponding private messages will be superposed as a new desired signal to be decoded, in order to avoid the decoding signal power being smaller than the interference one by means of successive interference cancellation (SIC). Specifically, we investigate and analyze the outage performance by satisfying the rate constraints for our proposed joint decoding scheme. Assuming Rayleigh fading channels, from the provided numerical results and simulations, they are well matched in terms of outage probability to clarify the correctness of the theoretical analysis, as well as illustrate the superiorities of our proposed scheme compared with conventional RSMA. The research results provide a theoretical basis for the development of future multi-user decoding.