Outgoing-Flows-Number Based Service Differentiation for Fair and Efficient Medium Access Control in Wireless Ad Hoc Networks

In a wireless ad hoc network, nodes share a broadcast channel through a Medium Access Control protocol. The broadcasting channel is a scarce resource, so MAC algorithms must reduce collisions and ensure high network throughput. The IEEE 802.11 MAC protocol used in ad hoc networks can lead to unfairness in channel utilization among flows, some nodes may grab the channel for a long time and deprive the other nodes of accessing the channel. In this paper, a new approach to make the Medium Access Control in wireless ad hoc networks more efficient and fairer is proposed. This approach is based on a service differentiation between the nodes of the network by taking into account, for each node, the number of its outgoing flows. The principle of this approach is to give a node a bandwidth that must be proportional to the number of its outgoing flows. In that way, if a node has more outgoing flows than another or is more involved in routing than another it will have a high priority to access the channel. As a consequence of this approach, the network won’t break down because of the cooperation of all the nodes of the network, and bandwidth sharing will be fairer and more efficient.