Topological Design and Routing for Leo Satellite Networks

We investigate a topological design and routing problem for Low-Earth Orbit (LEO) satellite communication networks where each satellite can have a limited number of direct inter-satellite links (ISL's) to a subset of satellites within its line-of-sight. First, we model LEO satellite network as a FSA (Finite State Automaton) using satellite constellation information. Second, we solve a combined topological design and routing problem for each connguration corresponding to a state in the FSA. The topological design (or link assignment) problem deals with the selection of ISL's, and the routing problem handles the traac distribution over the selected links to maximize the number of carried calls. In this paper, this NP-complete mixed integer optimization problem is solved by a two-step heuristic algorithm that rst solves the topological design problem, and then nds the optimal routing. The algorithm is iterated using the simulated annealing technique until the near-optimal solution is found. The link assignment table and the routing table that are pre-calculated oo-line for each state are loaded into the satellites and a new set of these tables are retrieved at each state transition. The simulation result shows that the proposed method is applicable to practical LEO satellite networks.