Routing and Multicast Algorithms for LEO Satellite Networks

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Low Earth Orbit (LEO) satellite systems provide global coverage with short round trip delays. With these properties they will play a crucial role in the global Internet to support real-time and non-real-time applications. Routing and multicasting in LEO satellite systems are the key issues to support these services. Non-real-time applications are characterized by relaxed delay bounds. They are also insensitive to the variations in delay. Thus, datagram-based routing schemes can be used to support this type of traffic. the Semi-Centralized Datagram Routing Protocol (SC-DRP) is proposed to support connectionless routing in LEO satellite networks. The SC-DRP aims to foward the packets in the LEO satellite network on minimum delay paths. SC-DRP utilized LEO and MEO/GEO satellites to calculate routing tables, which will increase the reliability and delay performance of datagram traffic in satellite networks, where the data traffic is carried in the LEO satellite network. The Datagram Multicast Protocol (DMP) is proposed to support connectionless multicasting. DMP is based on the SC-DRP and creates shortest path trees. Real-time applications impose strict delay bounds and are sensitive to delay varations. Thus, real-time traffic can be supported by connection-oriented routing schemes. The changing connectivity pattern of satellites affects the estbalished paths in LEO satellite networks. Thus, determining stable paths is very important. The Delay-Coupled Probabilistic Routing Protocol (DC-PRP) is proposed for connection-oriented routing in LEO satellite networks. DC-PRP computes paths conforming to the delay and delay jitter bounds of the connections. The Connection-Oriented Multicast Protocol (LEOCOM) is proposed for the connection-oriented multicasting, which creates delay-constrained multicast trees. The multicast tree length is optimized using a greedy search algorithm.