Many schemes have been proposed to enhance throughput or fairness of the original IEEE 802.11 standard, however, they either fail to consider both throughput and fairness, or to do so with complicated algorithms. In this paper, we propose a new MAC scheme that dynamically optimizes each active node’s backoff process. The key idea is to enable each node to adjust its Contention Window (
) to approach the optimal one that will maximize the throughput. Meanwhile, when the network enters into steady state in saturated case, i.e., under heavy traffic load, all the nodes will maintain approximately identical
s, which guarantees fair share of the channel among all nodes. Through simulation comparison with previous schemes, we show that our scheme can greatly improve the throughput no matter the network is in saturated or non-saturated case, while maintaining good fairness.