An Improved Earliest-Delivery Routing Algorithm in Double-layered Satellite Delay Tolerant Networks

Since presented by K. Fall, the new-type network Delay and Disruption Tolerant Network (DTN) came to become a hot area of research. In recent years, many kinds of DTN routing algorithms have been proposed. With the characteristics of long time delay, high packet loss rate and intermittent connectivity. Satellite networks also belong to a kind of DTN. But meanwhile, they have their unique characteristics of satellite nodes regular running in orbits and predictable inter-satellite links on and off, for which deterministic routing algorithm is more suited in Satellite DTN networks. This paper focuses on studying the theoretical knowledge of a kind of deterministic DTN routing algorithm, Earliest-Delivery(ED) algorithm. And combining with the characteristics of the satellite network above, we propose an improved ED algorithm from three aspects of distributed routing, routing update strategy and tag - based dynamic storage scheme. Ultimately, we simulate the LEO/MEO two-layer satellite delay tolerant network in OPNET, and analyze the performance of two algorithms upon packet delivery ratio, average end-to-end delay and the number of packets destroyed in the storage queue. The result shows the improved algorithm performs better in satellite DTN network.