Improving the performance of delay based protocol in delivering real time media via early retransmission

Early Retransmission (ER) has already been shown to improve TCP-SACK´s performance in delivering time sensitive media. In this paper, we integrate the ER scheme into a delay-based TCP variant, namely TCP-PERT, and performs extensive ns2 simulation. Our results show that ER can also improve PERT´s performance in delivering real time media by reducing the latency caused by retransmission timeouts. Furthermore, we also explored the improvement brought by employing a finegrained retransmission timer, and compared it with ER. We find out a) ER outperforms fine grained timer in a variety of conditions and b) the combination of the two can further improve performance.