Dynamic Topology Control Strategy for LEO Mega-Constellation Networks

With the development of mobile communications, low earth orbit (LEO) mega-constellation networks (MCNs) have become an essential part to support future 6G and Internet-of-Things (IoT). In LEO MCNs, topology control strategy play an important role in providing low latency as well as high energy efficiency, and has become a hot research topic. In this paper, we introduce dynamic cross-orbit links and investigate the dynamic topology control (DTC) problem in laser inter-satellite links (LISLs)-based MCNs. Firstly, we propose a practical dynamic link establishment model which considers several factors of cross-orbit links, such as the maximum communication distance between satellites, terminal alignment requirements and the duration of a LISL. Then, the DTC problem is formulated as an NP-hard binary integer programming problem aiming to minimize the average hop count and the number of dynamic LISLs. Furthermore, a heuristic bi-directional velocity discrete particle swarm optimization algorithm is developed to solve the above problem. Finally, simulation results show that our proposed dynamic topology control strategy can significantly decrease the average hop count and the number of LISLs compared with other baseline strategies. In particular, compared with Grid+, these metrics are reduced by roughly 42% and 13% respectively. This can provide us with some insights that using cross-orbit links in a DTC strategy can significantly improve the performance of LEO MCNs.