A new eifs strategy for IEEE 802.11e wireless LANs

To improve the performance of IEEE 802.11e, many methods based on admission control mechanisms and adaptive contention window adjustment algorithms are proposed. In this paper, however, we do not use such typical approach to achieve this goal. Instead, we propose a new EIFS strategy for improving the performance in IEEE 802.11e. In IEEE 802.11e specification, the EIFS time delay is activated after a node initiates an unsuccessful transmission. The new EIFS strategy uses the same activation mechanism as the specification. The major difference between the standard EIFS and the new EIFS strategy is when to deactivate such time delay. In specification, a node deactivates the EIFS time delay whenever any node in system executes a successful transmission. However, in our proposed EIFS strategy, a node deactivates the EIFS time delay only when itself has a successful transmission. Performance results via simulations have shown that this new strategy is able to boost the system performance significantly over a wide range of scenarios. In addition, we analyze this strategy in details and reveal the tradeoff and the cost to implement this new strategy.