Rate-Division Multiple Access for Coexisting GEO-LEO Satellite Systems: A Traffic-Aware Throughput Maximization Precoder Design

arXiv:2408.01997v1 Announcement Type: New Abstract: Frequency coexistence between geostationary orbit (GEO) and low Earth orbit (LEO) satellite systems is expected to be a promising approach to address spectrum shortage. However, it is essential to manage mutual interference between GEO and LEO satellite systems for frequency coexistence. Specifically, line-of-sight interference, caused by LEO satellites moving close to the line-of-sight path between the GEO satellite and GEO users (GUs), can significantly degrade the throughput of the GEO system. This paper presents a novel rate-division multiple access (RSMA) with a super-common message for GEO-LEO coexisting satellite systems (CSS). By using a super-common message that GUs can decode, GUs can mitigate line-of-sight interference by successive interference cancellation (SIC). Furthermore, we formulate a traffic-aware throughput maximization (TTM) problem to satisfy heterogeneous user traffic demands by minimizing the total unsatisfied throughput demands (or user dissatisfaction). In doing so, the TTM precoder can be flexibly adjusted according to the interference leakage from LEO satellites to GUs and the target traffic demands. Numerical results confirm that our proposed method achieves seamless connectivity even in the GEO-LEO online interference regime under imperfect channel state information (CSI) at both the transmitter and receiver.