T-DLRP: Detection of Fast Retransmission Losses Using TCP Timestamp for Improving the End-to-End Performance of TCP over Wireless Networks

Improving the end-to-end performance of TCP over wireless networks has been an active research area. When TCP operates in wireless networks, the performance of TCP degrades significantly. It is well known that frequent retransmission timeouts are the leading source of TCP performance degradation over wireless networks. Retransmission timeouts are unavoidable, when the fast retransmission of a lost packet fails to reach the destination. There have been many schemes developed for reducing the retransmission timeouts of TCP. However, these schemes have no mechanism to detect the loss of fast retransmitted packets over wireless networks. In this paper, we introduce an efficient TCP mechanism, called T-DLRP, which is able to detect the loss of fast retransmitted packets and react accordingly. To justify our contributions, we compared T-DLRP against TCP New Reno, Vegas, New Jersey, Veno, Cerl, and DAC via extensive simulations using Qualnet 4.5 simulator. The results demonstrate that our mechanism achieves significant improvement over existing TCP variants especially in a coexisted network with packet loss and fast retransmission losses. Compared to DAC, T-DLRP gains more than 70% improvement in terms of accuracy over wireless networks. Also, our experiments of multiple connections of the same TCP flows reveal that T-DLRP has better fairness compared to TCP NewReno. 1. Introduction In the current Internet, Transmission Control Protocol (TCP) is used as the most popular transport layer protocol [1]. The congestion control algorithms of TCP are very essential for the stability of the Internet. However, the performance of TCP degrades rapidly when TCP operates in wireless networks [2]. Improving the end-to-end performance of TCP over wireless network has been an active research area in network community. The performance of TCP highly depends on its loss recovery algorithms such as fast retransmission and retransmission timeouts. The main reasons for the degradation of TCP throughput over wireless networks are the unnecessary reduction of congestion window size due to the inability of TCP sender to differentiate the transmission errors from network congestion, the causes of frequent retransmission timeouts [3]. TCP often loses several packets from one window of data and recovers these packets only after the expiration of retransmission timeouts which leads to reducing its end-to-end performance. In TCP, the sender detects packet loss by receiving three duplicate acknowledgments or the expiration of retransmission timeouts and treats every loss as an indication of