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 t he Earth surface. Satellites in the polar regions and the seam switch off t heir intersatellite links to the neighbor satellites. As a result, the conn ectivity pattern of the network changes. Ongoing calls passing through thes e links need to be rerouted. A large number of simultaneous rerouting attem pts would cause excessive signaling load in the network. Moreover, the hand over calls could be blocked because of the insufficient network resources i n the newly established routes or large connection re-establishment delay. In this paper, a routing protocol is introduced to reduce the number of rou ting attempts resulting from link connectivity change. The protocol does no t use the links that will be switched off before the connection is over. Si nce the call durations are not known a priori, the proposed protocol utiliz es a probabilistic approach. The performance of the protocol is evaluated t hrough simulation experiments. The experimental results indicate that the r outing protocol reduces the number of rerouting attempts resulting from con nectivity changes of the network.