The ever-increasing diffusion of the Internet Protocol suite has caused the Transmission Control Protocol (TCP) to become the most widely used for a reliable transport layer. Among the various functions performed by TCP, congestion control is one of the most important and delicate.

Due to the increasing number of streaming and interactive applications based on IP (i.e. VoIP, IPTV, etc.) new congestion control protocols for IP traffic are arising aside TCP, such as TCP Frendly Rate Control (TFRC) algorithm for Datagram Congestion Control Protocol (DCCP).

Unfortunately, high latency, bandwidth asymmetry, and transmission errors may remarkably affect the performance of  such congestion control protocols on terrestrial wireless and satellite channels. In particular, slow start algorithms may be too slow for broadband connections traversing long RTT links, thus resulting less efficient. On the other hand, satellite channels increase the amount of time that congestion avoidance algorithms need to increase the congestion window, when compared to terrestrial links.

VOTOS is a Focus Topic in the Joint Activity 2410 (Access, Network and Transport Layer Trials) of the European Satellite Communications Network of Excellence (SatNEx).

The main issue is the analysis of the behavior of congestion control protocols over satellite networks, with particular attention to those systems that adopt the most recent Demand Assignment Multiple Access schemes, such as Skyplex Data, Amerhis, BGAN, etc..

Analitycal studies, simulations, emulations, and real trials are the fundamental features of this topic.