Throughput Analysis of TCP on Channels with Memory

The focus of this paper is to analyze the relative sensitivity of the bulk throughput performance of different versions of TCP, viz., OldTahoe, Tahoe, Reno, and New Reno, to channel errors that are correlated. We investigate the performance of a single wireless TCP connection in a local environment by modeling the correlated packet loss/error process (e.g., as induced by a multipath fading channel) as a first-order Markov chain. A major contribution of the paper is a unified analytical approach which allows the evaluation of the throughput performance of various versions of TCP. The main findings of this study are that 1) error correlations significantly affect the performance of TCP, and in particular may result in considerably better performance for Tahoe and NewReno; and 2) over slowly fading channels which are characterized by significant channel memory, Tahoe performs as well as NewReno. This leads us to conclude that a clever design of the lower layers that preserve error correlations, naturally present on wireless links because of the fading behavior, could be an attractive alternative to the development or the use of more complex versions of TCP.