Bhuvana LN, Divya PD and Divya A, Easwari Engineering College, India

The usage of fixed buffers in 802.11 networks has a number of disadvantages associated with it. This includes high delay, reduced throughput and inefficient channel utilisation. To overcome this, a dynamic buffer sizing algorithm, the A* algorithm has been implemented at the access point. In this algorithm buffer size is dynamically adjusted depending upon the current channel conditions and hence delay is reduced and the throughput is maintained. But in 802.11 networks with DCF collision avoidance mechanism, it creates significant amount of unfairness between the upstream and downstream TCP flows, with clusters of upstream ACKs blocking downstream data at the access point. Thus a variation of the Explicit Window Adaptation (EWA) scheme has been used to regulate the queuing time of the upload clients by calculating the feedback value at the access point. This creates fairness and increases the number of transmission opportunities for the downstream traffic.

Wireless LANs(WLANs), Medium access control (MAC), Transmission control protocol (TCP), Dynamic Buffer sizing, Explicit Window Adaptation(EWA).