Effects of diversity routing on TCP performance in networks with stochastic channels

Abstract

Transmission Control Protocol (TCP) is a widely used transport protocol in today's multimedia applications. TCP was originally designed for wired networks, and its performance is highly degraded in networks with stochastically variable links, such as satellite and wireless networks. One significant class of degradation is caused by link dropouts, which may occur due to multipath fading effects in wireless networks, or due to signal attenuation by changing weather conditions and turbulence in satellite channels. In this thesis, we study the effects of a diversity routing strategy on TCP performance in networks with stochastic links. This strategy allows each data sender to send copies of data packets along multiple paths in order to reduce the probability of packet losses. We define TCP efficiency to be the ratio of a data sender's throughput to the network capacity used by this sender. We explore the optimization of TCP efficiency by varying the number of paths along which data packets are sent,denoted as n. We find the optimal number of diversity routing paths n* that maximizes the TCP efficiency, and we observe that the value of n* depends on the variability of the stochastic links.