Small Number but Big Influence: Analysis of Routing Usability in ISTN

Abstract

The integration of satellite and terrestrial network(ISTN) is an ongoing trend in prospect. Recently many commercial companies such as SpaceX, OneWeb plan to launch tens of thousands satellites which promotes the scale of satellite networks rapidly. While the scale of the satellite network is still small relatively compared with the terrestrial network. IP-routing ability in satellite network is becoming more and more important for ISTN. Suffering from high topology dynamics, long propagation delay, and onboard processing limitations on satellite networks, routing in ISTN faces many challenges worth analyzing in-depth.This paper builds an IP-based routing usability theoretical analytical model with calculable formula, which formulates different types of networks under a unified framework that accommodates various configurations and characteristics of multiple networks. Moreover, massive experiments based on real satellite motion data are designed and conducted to analyze the routing performance and challenges in ISTN deeply, combining various ground stations, satellite processing ability, number of satellites per orbit, etc. At last, with the analysis of routing usability for ISTN, some instructive conclusions are drawn. Although the number of routing nodes in satellite networks is relatively small compared with terrestrial networks, but the influence is big. With the network scale extending, high topology dynamics makes the IP-based routing performance of ISTN decrease dramatically. Routing usable time in one day period decreases from 23.36h to 2.99h when the number of satellites grows from 60 to 960. To keep routing usability, the number of satellites in space is not the more the better in ISTN. The scale of network and the onboard processing ability should do trade off.