Bandwidth Estimation for TCP Sources and Its Application

In this paper, we propose a novel bandwidth estimation algorithm for TCP connections and its possible application to congestion control mechanism. The estimation algorithm relies upon an analytic relation which expresses the connections’ available bandwidth as a function of the inter-departure time of packets and of the inter-arrival time of ACKs. It is worth noticing that this approach can be extended to protocols other than TCP, as long as they support an acknowledgment mechanism. The bandwidth estimation performance is assessed through discrete event simulations under various network topologies, traffic scenarios and link error conditions. Bandwidth estimation is then applied to TCP congestion control to select the value of the congestion window after a packet loss episode. Performance of this modified version of TCP is validated by means of simulations and compared to the one achieved by TCP NewReno. Finally, the possible coexistence of the modified version of TCP and TCP NewReno is proved through a detailed analysis of fairness and friendliness of the new protocol.