A Joint Minimum Hop and Earliest Arrival Routing Algorithm for LEO Satellite Networks

As a space-based component of space-air-ground integrated networks, low earth orbit (LEO) satellite systems have always been a research hotspot in space explorations thanks to the global coverage, short communication delay, low launch cost and strong survivability. However, the high dynamics of network topology and the time-varying distribution of link resources would deteriorate the quality of service (QoS) for LEO satellite networks. In order to reduce communication delay and ensure end-to-end (E2E) data transmissions, a joint minimum hop and earliest arrival (MHEA) routing algorithm for LEO satellite networks is proposed in this article. Firstly, based on the networking mode of Walker constellations, a coordinate graph (CG) model is proposed to accurately characterize both the topological structure and link resource distribution of time-varying networks in the two-dimensional Cartesian coordinate system. Afterwards, a CG-based minimum hop (MH) routing model is leveraged to calculate the minimum E2E hop count and determine the region of the minimum hop path. Finally, an earliest arrival (EA) strategy is proposed to determine the next hop node with the shortest delay. Simulation results demonstrate that the proposed MHEA routing algorithm not only reduces the route count, the hop count and the delay of E2E path, but also improves the file delivery ratio.