Contact plan design for navigation satellite network based on simulated annealing

By introducing inter-satellite links (ISLs), global navigation satellite system (GNSS) can achieve inter-satellite ranging, which can enable autonomous navigation, and inter-satellite communication, which can enable the GNSS to form a global network. Due to the resource constraints of satellite platforms, only limited number of ISLs (e.g. only one ISL) can be equipped on one navigation satellite, which makes the navigation satellite network a delay/disruption tolerant network (DTN). Generally, the number of ISLs is less than the number of visible satellites; thus, only those visible satellites which can together meet an overall goal shall be selected. Therefore, contact plan, which comprises all future contacts among satellites, needs to be carefully designed to accommodate the constraints of both inter-satellite ranging and inter-satellite communication. In this paper, a topology handling scheme based on finite state automaton is first presented as the orbiting of GNSS is periodic. Secondly, the contact plan design problem is formulated as a constraint optimization problem with the inter-satellite ranging as a constraint and inter-satellite communication delay as the optimization object. Thirdly, a heuristic algorithm based on simulated annealing is proposed to compute the contact plan. Simulation results show that the delay performance of optimized contact plan is improved and the delay of contact graph routing under optimized contact plan is also improved.