II. QOS AND LIMITATIONS OF IEEE 802.11 In term of qualitative and quantitative characteristics

window, collision, IEEE 802.11e, EDCF. Abstract—The Enhanced Distributed Channel Access (EDCA) is introduced to provide QoS on the basis of Distributed Coordination Function (DCF) in IEEE802.11. The access mechanism of IEEE802.11e, referred to as EDCA, assigns different access categories (AC) with different types of data traffic based on priorities. Each priority uses a different set of medium access parameters to introduce QoS support. This led to the introduction of the principle of the virtual collision among stations also among access categories. The virtual collision occurs mainly due to same independent backoff value within the station or with other stations. In this paper, the effect of the virtual collision management of EDCA is presented on its fairness among other properties. Moreover, we proposed to enhance the EDCF performance with the fine tuning of the minimum contention window along with the AIFSN (Arbitration Interframe Space Number) value that depends on the traffic load.