Affiliations: Jozef Stefan Institute, Jamova 39, Ljubljana, SI-1000, Slovenia Tel.: +386 1 4773112; Fax: +386 1 4773111; E-mail: Ales.Svigelj@ijs.si, Mihael.Mohorcic@ijs.si, Gorazd.Kandus@ijs.si
Note:  Corresponding author.
Abstract: The provision of multimedia services via a non-geostationary satellite system characterised by highly dynamic conditions requires advanced traffic engineering procedures, including adaptive routing and adaptive forwarding. In this paper we assess traffic class dependent routing in the low earth orbit satellite system with a packet switched intersatellite link network. Traffic class dependent routing is enhanced with adaptive forwarding based on local link load information, which selects the most suitable of the two alternative shortest paths to the destination without any link status distribution between neighbouring nodes. The performance of the proposed forwarding policy is evaluated in two different traffic load scenarios, using a specifically developed simulation model. The simulation results are presented in terms of average packet delay in the network, average normalised data throughput and positions of satellites with critically loaded links. The simulation results indicate that the use of traffic class dependent routing with adaptive forwarding based on local link load information improves the network performance significantly in terms of all performance measures, and that the number of critically loaded links is drastically decreased due to the fast response of the adaptive forwarding policy to congestions on the link.
Keywords: Traffic class dependent routing, link-cost function, LEO constellation, ISL