Comparative study of various TCP versions over a wireless link with correlated losses

In this paper, we investigate the behavior of the various transmission Control Protocol (TCP) algorithms over wireless links with correlated packet losses. For such a scenario, we show that the performance of NewReno is worse than the performance of Tahoe in many situations and even OldTahoe in a few situations because of the inefficient fast recovery method of NewReno. We also show that random loss leads to significant throughput deterioration when either the product of the square of the bandwidth-delay ratio and the loss probability when, in the good state exceeds one, or,the product of the bandwidth-delay ratio and the packet success probability when in the bad state is less than two. The performance of Sack is always seen to be the best and the most robust, thereby arguing for the implementation of TCP Sack over the wireless channel. We also show that under certain conditions the performance depends not only on the bandwidth-delay product but also on the nature of timeout, coarse or fine. We have also investigated the effects: of reducing the fast retransmit threshold.