A novel scheme for optimizing contention window adjustment in IEEE 802.11e wireless networks

Wireless LAN 802.11 is one of the widely used specifications for wlan networks. 802.11 e has increased its utility and QoS by assigning priorities to different types of data packet. Method employed by 802.11e at its MAC layer specification determines the channel access mechanism, known as EDCF. The fixed approach of EDCF of increasing the CW size without taking in consideration channel condition results in low performance at high network size. The very fundamental concept of increasing CW according to fixed scale in itself shows lack of dynamic adaption of cw according to network condition. In this paper, we introduce a new technique of determining the size of cw for backoff procedure. The mechanism proposed FHCW does take into account history of previous transmissions and fuzziness present in the channel due to various factors namely-congestion, sensing credibility of station and priority of packet to be sent. Performance comparison of both the techniques show the capability of proposed scheme.