Application layer relays for wireless 802 . 11 mesh networks

Multi-hop wireless mesh networks have received considerable attention recently. The predominant network protocol used in such networks is likely to be TCP. However, the performance of TCP degrades quickly as the number of hops increases. How to improve the performance of TCP over multihop wireless mesh network, especially given the existing 802.11 MAC, has been an interesting research problem. Application layer relay method, which splits a traditional end-to-end TCP connection into several short hop connections, has been proposed as a solution in the wired world to improve the TCP performance. In this paper we investigate application layer relays in 802.11 wireless mesh networks and develop a model to analyze TCP performance in such networks. With the present of relays, the nodes in wireless networks act more independently and the round trip time is reduced also. However, relays also increase competition within the network. To reduce the competition, we propose a simple scheduling process to coordinate the relay nodes. The experiments show that relays with scheduling can achieve up to 50% performance gain in a 4-hop network.