Analysis and Strategies of Wireless Caching-Assisted Rate-Splitting Multiple Access

The growing number of connected devices in 6G networks requires advanced multiple access (MA) techniques and caching strategies to efficiently manage interference and enhance data rates. Caching offers a promising solution by storing frequently requested content at the network edge, reducing latency and alleviating backhaul congestion. Integrating caching with MA techniques is paramount for realizing the next-generation networks. Rate-splitting MA (RSMA) has emerged recently as a key candidate for future networks, due to its flexibility in managing interference and enhancing spectral efficiency. This paper presents a study on the performance of cache-aided RSMA (CA-RSMA) systems, which enhances the signal-to-noise-plus-interference (SINR) ratio. A multi-antenna equipped transmitter uses superposition coding, and two single-antenna equipped receivers use their cached content to remove the interference, which improves the SINR. We derive analytical expressions for key metrics, including probability of successful decoding (PSD), outage probability (OP), rate region and the weighted sum rate (WSR) for CA-RSMA. Furthermore, we formulate constrained optimization problems to maximize the PSD and WSR, in terms of the power allocation coefficients. Simulation results validate our analysis, and we show that CA-RSMA outperforms the conventional RSMA, non-orthogonal multiple access (NOMA), space-division multiple access, in terms of the considered metrics. A performance comparison shows that CA-RSMA outperforms CA-NOMA in terms of RR and WSR at an expense of PSD.