This letter presents a new and simple model for a TCP flow experiencing random packet losses due to both transmission errors and congestion events. From this model, we will derive a straightforward expression of a unified loss probability (ULP). This ULP gives the opportunity to reuse classical analytic models to analyze the performance of TCP and to size the buffer to optimize the wireless link utilization. Extensive simulations using TCP Reno in ns-2 demonstrate that our model is valid not only for the extreme cases where either transmission errors or congestion losses dominate but also in the situations where both types of losses are significant.

Peer Reviewed