Functioning of TCP Algorithms over a Wireless Link

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In this paper, we investigate the behavior of the various algorithms of TCP, the Internet datatransport protocol, over wireless links with correlated packet losses. For such ascenario, we show that the performance of NewReno is worse than theperformance of Tahoe in many situations and even OldTahoe in a few situations on account of the inefficientfast recovery method of NewReno.

We also show that random loss leads tosignificant throughput deterioration when either the product of the squareof the bandwidth-delay ratio and the loss probability when in the good state exceeds 1 or the product of the bandwidth-delay ratio and the packet successprobability when in the bad state is less than two.

The performance of Sackis always seen to be the best and the most robust thereby arguing for theimplementation of TCP SACK over the wireless channel. We also show thatunder certain conditions the performance depends not only on thebandwidth-delay product but also on the nature of timeout, whether coarse orfine. We have also investigated the effects of reducing the fast retransmitthreshold.