Precomputed Routing in a Store and Forward Satellite Constellation

Satellite constellations like Orbcomm provide store and forward message communication services. Inter-satellite links (ISL) are not considered in order to keep the system simple and the costs moderate ([1], [2]). Rather, gateways may act as relays between satellites. In this context, routing is important because it helps to control the end-to-end delay and resources utilization (e.g. on-board memory). However, routing must face frequent changes and partitioning of the network because of the satellite motion. Similar routing problems have been studied in the transportation field (e.g. subway and railways). In this contribution, the shortest path problem with time windows (SPPTW) is applied to satellite constellations and a pre-computed routing algorithm is derived. Simulation results show how this algorithm reduces the end-to-end delay of the routes.