An analytical model for the various TCP algorithms operating over a wireless channel

In this paper we have studied the behavior of the different TCP algorithms on mobiles operating at different speeds. In order to do this we first describe a method of modelling the behavior of the various TCP versions analytically. We show that TCP Sack has the best performance of all the TCP versions in terms of link utilization thereby arguing for the widespread implementation of TCP Sack. We also show that at low speeds Tahoe is a better option compared to New Reno while at high speeds the performance of Sack and New Reno is similar. We then use the analytical model to characterize the loss probability region for high link utilization. From this we also derive approximate conditions on the buffer sizes at various speeds for which the link utilization will be high. Thus we show that at low speeds the performance is sensitive to the buffer size within certain limits. On the other hand at high speeds changing buffer capacity does not lead to much change in the link utilization