A Reliable Transport Protocol for Unreliable Networks

Unstable networks such as wireless mobile ad hoc networks (MANETs) are radically different from traditional fixed networks like the Internet. The success of these emerging networks is determined by the performance of the communication layers and the transport layer. For the latter, many protocols have been proposed based on adaptations of TCP for such unstable networks. In this paper, we claim that the underlying principles of TCP are not suitable for unstable networks and propose a fundamentally different reliable transport protocol called SAFT. SAFT employs the store-and-forward principle to enable data transfer across networks with intermittent end-to-end connectivity. Using simulations, we show that SAFT realizes faster data transmission and uses network resources more efficiently than TCP. Furthermore, SAFT behaves more fairly when multiple connections compete for network resources in the same collision domain. We argue that our transport protocol results in several benefits including robustness, flexibility, and fairness.