Dynamic Switching Strategy for Cooperative Satellite-Terrestrial Networks

The integration of Low Earth Orbit (LEO) satellite constellations into 6G networks introduces significant challenges in mobility management and backhaul reliability due to frequent handovers. This paper proposes a novel cooperative dynamic switching and Group Head (GH) selection strategy utilizing a Space-Time Graph (STG) framework to enhance the reliability of LEO Satellite-Terrestrial Networks. This framework ensures reliable backhaul connectivity by leveraging the time-varying network topology. Unlike traditional snapshot-based methods, the proposed approach employs a Heuristic Window Selection algorithm on the STG structure to perform look-ahead optimization. The proposed strategy ensures Quality of Service continuity under poor channel conditions by balancing conflicting objectives, including ground-to-satellite and inter-satellite link connectivity and switching frequency, and by incorporating an adaptive power ramping mechanism. Additionally, the study shows that transitioning the constellation into sequential formations increases the number of candidate satellites, which improves system robustness by enabling the selection of superior communication links. The proposed multi-objective strategy significantly outperforms baseline methods in terms of minimizing unnecessary GH switching and optimizing operational costs even if poor channel conditions.