A Transport Layer Mechanism for Fair TCP Throughput over 802.11 Multi-Hop Wireless Mesh Networks

Cities around the world have planned and implemented large-scale wireless mesh network deployments. These mesh deployments are expected to provide broadband mobile access to the Internet at a low-cost to the user. This paper considers the fairness problem for nodes in multihop wireless mesh networks. Many existing approaches are unsuitable because they require modifications to the IEEE 802.11 MAC protocol or node queueing operations. Such modifications require a change of hardware/firmware at every nodes in the wireless mesh network. Those approaches thus are less favorable from the interoperability and cost point of view. Without modifying the lower layer protocols, this study identifies TCP parameters that impact throughput fairness and proposes adjusting those parameters to reduce frame collisions and improve throughput fairness. Using simple mathematical formulations and ns2 simulations, this study shows that the frame transmissions from each node can be effectively controlled by properly controlling the delayed ACK timer and using a suitable advertised window. In addition to fairness, the proposed method requires fewer buffer resources than other methods. The proposed method is simple and easy to deploy.