Improving MAC Layer Fairness in Multi-Hop 802.11 Networks

Wireless adhoc networks consist of nodes interconnected by wireless multi-hop communication paths. Such networks exhibit simulated mobility, where the topological changes are caused by nodes coming up or going down. These networks also exhibit complex overlapping of flow paths. This in turn leads to severe contention in between flows as well as between the sub-flows of the same flow. In this paper, we analyze the unfairness of IEEE 802.11, in case it is extended for multi-hop networks. Thereafter we demonstrate how a simple, distributed algorithm can be put in place to approximate an ideal scheduler like round-robin and provide fair access to all the flows. Our simulation results clearly show that such an approach outscores the existing standard on fairness grounds. Additionally we also gain in terms of throughput by reducing the number of collisions.