Resource allocation for RSMA-aided multibeam satellite communications

This paper investigates the resource allocation for rate-splitting multiple access (RSMA) enabled multibeam satellite communication systems. Specifically, we minimize the total unmet user rate, which denotes the difference between the users' rate requirement and the practical achievable rate, as well as the total transmit power of the satellite by optimizing the precoding, power allocation, and rate allocation, under the per-feed power and rate constraints. To solve the non-convex optimization problem, a two-stage scheme is proposed. In particular, in the first stage, we present a precoding scheme by maximizing the signal-to-leakage-plus-noise ratio of each beam to eliminate the inter-beam interference. In the second stage, we introduce auxiliary variables to obtain an upper bound on the objective function under the given precoding matrix and transform the rate constraints of the original problem into second-order cones (SOC) and linear matrix inequations (LMI). Then, the successive convex approximation (SCA) technique is used to obtain suboptimal power and rate allocation solutions. Moreover, the initial feasible solution for power allocation is provided by using the standard interior point method. Finally, numerical results verify the superiority of our proposed solution compared to the benchmark methods in terms of objective function values.