The IEEE 802.11e draft has been introduced to provide QoS to the real time applications in wireless network. The new MAC protocol mainly defines HCF (Hybrid Coordination Function) and EDCF (Enhanced Distributed Coordination Function). EDCF is a contention based channel access scheme and is a part of HCF for infrastructure network. In this paper, we proposed to enhance the EDCF performance with the fine tuning of the minimum contention window along with the randomized AIFSN (Arbitration Interframe Space Number) value that depends on the traffic load. The main purpose of our paper is to reduce collision in the WLAN that is caused due to small contention window.