A Lightweight Hierarchical Mobility Management Architecture for Ultra-Dense LEO Satellite Network

As one of the most promising architecture in the evolving sixth-generation (6G) systems, ultra-dense low Earth orbit (LEO) satellite network (UD-LSN) is drawing increasing attention due to its global coverage and ubiquitous access. To ensure service continuity, mobility management with provision of seamless handover is crucial in the process of satellite and user movement. However, massive service requests and overlapped satellite coverage will result in frequent handovers and diversified options in the UD-LSN. Meanwhile, existing mobility management methods based on the terrestrial networks are difficult to make timely and effective decisions due to the limited deployments of ground stations. In light of this, we propose a two-layer grouping and clustering based mobility management architecture (GCMMA) for the UD-LSN to reduce the management complexity with supporting the flexible function configurations. Under the GCMMA, we design lightweight handover procedures for different scenarios according to the established handover model, which considers user aggregation and combines with the regularity of satellite motion. Simulation results validate the effectiveness of the proposed mechanism, which has a better performance in handover delays and signaling overheads.