A Low-Complexity Return-Link Beam-Hopping Scheduling for NGSO Mega-Constellations With Dynamic Topology and Uneven Traffic

Nongeostationary orbit (NGSO) constellations characterized by seamless coverage and high throughput have been envisioned as a promising solution to 6G, where beam hopping (BH) technique plays an indispensable role to achieve on-demand service. However, owing to the dynamic topology and uneven terrestrial traffic, how to effectively manage multisatellite time-frequency-spatial beam resources to match the heterogeneous demands is challenging for NGSO satellite operators. This article proposes a novel return-link BH scheduling framework for NGSO mega-constellations, where the ground resource management center periodically executes BH scheduling for users in Earth-fixed cells to improve the long-term average service satisfaction (ASS) while reducing the intersatellite handover. Specifically, we decouple the NP-hard scheduling problem into three subproblems, namely, user-satellite association problem, BH pattern design problem and resource block (RB) allocation problem. User-satellite association problem is solved by a low-complexity heuristic algorithm to reduce the handover and avoid intersatellite interference. Furthermore, a graph-based maximum weight method and an iterative scheme based on successive convex approximation are developed to obtain the BH patterns and RB allocations, respectively. Simulation results demonstrate that compared with other benchmarks, such as the best channel association and round-robin BH schemes, the proposed method can reduce the satellite load unevenness by 60% and improve the ASS by 35% while maintaining a low handover overhead.