Distributed opportunistic communication protocol for wireless multihop networks

Despite significant research effort, the performance of distributed medium access control methods has failed to meet theoretical expectations. Previously, we have proposed the concept for a fully-distributed, but non-optimum opportunistic medium access control called Channel MAC. In this paper, we present the Channel MAC protocol operations addressing the issues of information exchange between nodes, predicting transmission intervals and selecting transmission thresholds to achieve fairness. Although the proposed prediction scheme based on mean channel fading is simple to implement, it is imperfect leading to some performance losses. Event based simulation tool NS2 is used to analyse the performance of Channel MAC in a number of network scenarios. We analyse the performance of the proposed protocol using the performance metric; throughput, fairness and delay. The simulation results show throughput performance improvement of up to 30% with Channel MAC over IEEE 802.11 in certain multihop scenarios. Generally, the proposed protocol outperforms 802.11 in all analysed network scenarios. We also show that the severe resource starvation problem (unfairness) of IEEE 802.11 in some network scenarios is reduced by the Channel MAC mechanism.