Comparative Performance Evaluation of TCP Variants on Satellite Environments

Satellite communications are essential to provide Internet access to wide areas, helping bridge the "digital divide". However, long RTTs and the possible presence of losses due to satellite channel errors, severely impair standard TCP performance. To overcome this problem several approaches are possible, including the adoption of enhanced versions of TCP. This paper focuses on these, by presenting the results of a comparative performance evaluation carried out in a satellite environment through a Linux testbed. The interest of the analysis lies in the wide variety of TCP variants considered and in the different aspects analyzed, such as performance at start-up, level of RTT unfairness and robustness against link losses. The results are analyzed at length in the paper and give interesting indications about the performance achievable on satellite channels by the most promising TCP variants proposed in recent years.