A Capacity Analysis Model for Large-Scale Two-layered Satellite Networks

The rapid expansion of Low Earth Orbit (LEO) satellite networks and has heightened the need for preliminary evaluations of network capacity. However, accurately modeling Multi-Layer Satellite Networks (MLSN) capacity poses significant challenges due to dynamic topologies, complex traffic flows, and multi-layer configurations, etc. Therefore, in this paper we propose a capacity analysis model for large-scale, two-layered satellite networks. Initially, based on the current neighborbased inter-satellite link (ISL) establishment rules, we establish a two-layered collaborative satellite network transmission model with delay constraints, where higher-layer satellites assist with communication to mitigate delays caused by excessive relays in lower-layer satellites, thereby reducing the number of hops for long-distance transmissions. Subsequently, we derive a capacity analysis model by comparing traffic demand with network transmission capabilities. By employing a region-based Binary Point Process (BPP) to model gateway satellites, we provide analytical expressions for both service and network transmission capacity. Simulation and analysis results indicate that both the average service transmission capacity and the network transmission capacity exhibit an asymptotic relationship with the scale of LEO satellites, represented as Θ(1/Na). Furthermore, simulation results reveal optimal configurations for the number of LEO satellites, gateways, LEO/Geostationary Earth Orbit (GEO) switching points, and the distribution density of gateway satellites that maximize transmission capacity. The results also indicate that current neighbor-based link establishment rules are inadequate for future large-scale satellite networks, necessitating the development of new ISL mechanisms.