TCP Behaviour in a DVB-RCS Environment
Cesare Roseti, Erling Kristiansen · 24th AIAA International Communications Satellite Systems Conference · 2006
In 2000, ETSI has approved and published a standard for interactive broadband satellite services (DVB-RCS) . One of the most important features of this standard is the implementation of DAMA strategies aiming at a fair and efficient use of the shared resources in the satellite return channel. A DAMA scheme introduces a new control loop, based on a signaling exchange between STs and the NCC, installed in the GW. As a consequence, a new component is added to the overall end-to-end delay: The “access delay”. TCP, on the other hand, the transport protocol used by most current Internet applications, is based on the RTT experienced in the network. Therefore, performance of TCP over DVBRCS is effectively governed by two nested control loops with similar time constants. Depending on the circumstances, these two nested control loops may cooperate to give good performance, or may interact in a way that degrades performance. This paper analyses the interaction between the TCP and DVB-RCS control loops by exploring the performance of TCP over the different capacity allocation categories defined in the DVB-RCS standard. An access simulator, based on ns-2 , has been implemented and used to study the dynamics at both MAC and TCP layers, as well as their cross-interaction. Furthermore, a set of analysis approaches, including theoretical treatment, emulation and real measurements are presented as complementary tools to have an exhaustive knowledge about TCP performance in DVB-RCS environment.