Joint Power Allocation and User Association in CR-Inspired D-RSMA for LEO Satellite Networks With GEO Spectrum Sharing
With the rapid development of satellite communications, low Earth orbit satellite networks have attracted considerable attention because of their high data delivery capability and low propagation delay. However, the increasing scarcity of frequency resources has become a major obstacle to their large-scale deployment. To address this issue, this paper proposes a resource optimization framework that combines cooperative single-layer distributed rate-splitting multiple access with cognitive radio to improve spectrum utilization in satellite systems. A coexistence communication model is established for a secondary low Earth orbit satellite network and a primary geostationary Earth orbit satellite network. Based on this model, the maximum achievable sum rate of the low Earth orbit system is obtained by optimizing the transmit-power allocation and common-rate allocation variables under minimum mean square error-based precoding. The resulting optimization problem is efficiently addressed by a greedy-and-swap user-association strategy combined with the successive convex approximation algorithm. Numerical simulation results verify that the framework proposed in this paper features fast convergence. Comparative analyses against ablation experiment frameworks and multiple access benchmark frameworks demonstrate that the proposed joint resource allocation distributed rate-splitting multiple access framework can improve the performance of low Earth orbit satellite communication systems while satisfying multiple constraint conditions.