A Hybrid Routing Strategy for Congestion Mitigation in LEO Mega-Constellation Networks with Constrained Gateway Placement

As a crucial component of future space-terrestrial integrated networks, Low Earth Orbit (LEO) mega-constellation networks are facing increasingly prominent network congestion issues due to surging user demands, particularly around gateways with geographical constraints. To address this network congestion problem, this study proposes a user-to-gateway routing approach that implements a hybrid routing strategy for congestion mitigation (HRS-CM) under restricted gateway deployment conditions. The HRS-CM consists of three phases: an access satellite selection phase based on hop count evaluation models, a semi-distributed multi-hop congestion avoidance routing phase based on link costs, and a gateway-centered load balancing routing phase. All three phases are modular, allowing for flexible combinations of partial phases. Compared to traditional methods, the proposed approach achieves significant reductions in communication delay and average hop count while maintaining high performance in terms of data delivery ratio and throughput. The simulation results demonstrate the superior performance of the proposed approach in scenarios with geographically constrained gateway deployment conditions.