Performance improvement of TCP-based applications in a multi-access satellite system

This paper describes a TCP splitting solution for multi-access bent-pipe GEO satellite networks. Such networks have a star topology with a large number of user terminals connected to a hub over a satellite link with broadcast downlink and multi-access uplink. In such systems, besides improving the end-to-end performance of TCP, efficient usage of the multi-access uplink is a key design objective. Most of the work done in the area of TCP over satellite so far has focused on TCP splitting in point-to-point satellite links. In this paper we first discuss the resource allocation issues involved in TCP splitting over multi-access satellite links. We then propose a TCP splitting scheme that uses Satellite Transport Protocol [13] and is well integrated with the MAC protocol. We propose an efficient and fair scheduling algorithm at the hub for uplink bandwidth allocation which works together with Bandwidth on Demand (BoD), wherein the terminals request for time slots to send data over the uplink. We mainly concentrate on improving the performance of HTTP like applications which are characterized by short bursty requests from clients to servers. We have developed the ns simulator to have several new modules that can be used to simulate a whole new range of satellite-terrestrial network topologies, transport level proxies, and TCP and STP flow control behavior.