Satellite systems performance with TCP-IP applications

Satellites are well suited for mobile Internet applications because of their capability to enhance coverage and support long-range mobility. Satellites are an attractive alternative for providing mobile access to the Internet in sparsely populated areas where high bandwidth UMTS cells cannot be economically deployed or in impervious regions where deployment of terrestrial facilities is not practical. In this paper we analyze various mobile Internet applications for both GEO and LEO satellite configurations (Iridiumlike and Globalstar-like.) For the simulations, we use ‘ns2’ (Network Simulator 2), enhanced to support LEO and GEO satellites and mobile terminals. As part of the ns-2 upgrade, we developed a channel propagation model that includes shadowing data from surrounding building skylines. We compute via simulations the performance of FTP applications when users are mobile, traveling along “urban canyons”. The results show that throughput and delay performance is strongly affected by skyline shadowing and that shadowing degradation can be compensated by satellite diversity, such as provided by Globalstar.