A routing algorithm for connection-oriented Low Earth Orbit (LEO) satellite networks with dynamic connectivity

Low Earth Orbit (LEO) satellites move with respect to a fixed observer on the Earth surface. Satellites in the polar regions and the seam switch off their intersatellite links to the neighbor satellites. As a result, the connectivity pattern of the network changes. Ongoing calls passing through these links need to be rerouted. A large number of simultaneous rerouting attempts would cause excessive signaling load in the network. Moreover, the handover calls could be blocked because of the insufficient network resources in the newly established routes or large connection re-establishment delay. In this paper, a routing protocol is introduced to reduce the number of routing attempts resulting from link connectivity change. The protocol does not use the links that will be switched off before the connection is over. Since the call durations are not known a priori, the proposed protocol utilizes a probabilistic approach. The performance of the protocol is evaluated through simulation experiments. The experimental results indicate that the routing protocol reduces the number of rerouting attempts resulting from connectivity changes of the network.