Evaluation of a Stateful Transport Protocol for Multi-channel Wireless Mesh Networks

An effective transport protocol for a wireless mesh network (WMN) must fairly and efficiently allocate the limited network resources among multiple flows sharing the network while minimizing the performance overhead it incurs. While many transport protocols have been proposed specifically for multi-hop wireless networks, most of them refrain from keeping state in the intermediate network nodes. In this paper, we focus on the other extreme of the design space: stateful transport protocol, and study the research question of how much performance improvement is possible if intermediate network nodes could maintain as much state as needed. We present the design of a stateful transport protocol, named link-aware reliable transport protocol (LRTP), and examine how LRTP can fairly and efficiently allocate the network resources by accurately estimating the sending rate of each flow traversing the network using information about effective physical link capacity and the number of sharing flows. LRTP reduces the performance overhead associated with reliable packet delivery by leveraging the link-layer retransmission mechanism to eliminate per-packet end-to-end acknowledgments and unnecessary packet transmissions. Experiments conducted on an IEEE 802.1 la-based multi-channel wireless mesh network testbed as well as ns-2 simulations demonstrate that LRTP can achieve significant improvements in both overall network throughput and inter-flow fairness, especially on wireless networks with channel errors, when compared with the de facto Internet transport protocol TCP, and state-of-the-art MANET transport protocols such as ATP.