BA-TCP: a bandwidth aware TCP for satellite networks

In the presence of satellite channels, one of the most challenging problems for TCP is to achieve fair bandwidth sharing among several competing connections with round-trip propagation delays that may differ by more than two orders of magnitude. The bandwidth-aware TCP (BA-TCP) provides a fair solution while maintaining the end-to-end semantics of transport protocols. At the same time, it allows backward compatibility and it does not require substantial changes to the existing TCP. In BA-TCP, the network layer is assumed to be able to convey propagation delay and available bandwidth measurements to end users, for instance using IPv6 optional fields. TCP receivers employ this information to compute a generalized advertised window, which, in turn, controls the amount of data the source injects into the network. Experimental results show that a satellite connection can fairly share a bottleneck with wired connections. Furthermore, since BA-TCP exploits the bandwidth-delay product to control the source congestion window, the queuing delay at the bottleneck link tends to zero at steady state and buffer overflow is negligible in most situations.