Rate-Splitting Multiple Access for Cluster-based Beam Hopping Satellite Communication Systems

Beam hopping technology, known for its flexible onboard resource allocation capabilities, has been widely applied in satellite communication systems and has recently become a prominent research focus. However, when adjacent beams are illuminated simultaneously, they may encounter inter-beam interference issue. This paper initiates the study of rate-splitting multiple access for cluster-based beam hopping (CBH) satellite communication systems. Specially, we introduce a metric-the ratio of offered capacity to traffic demand-to measure fairness among beams within clusters by optimizing the precoding vector and CBH pattern design under the powers, rate allocation, and CBH pattern constraints. Due to the coupling of optimization variables, we formulated a problem as a format of mixed integer non-convex programming. Then, we decomposed this into two sub-problems, which are tackled using the weighted minimum mean-square error and low-complexity greedy-based approaches. Numerical results indicate that the proposed scheme increases minimum traffic satisfaction rate by $10.78 \%$ relative to the spacedivision multiple access baseline scheme.