Improving Throughput in Wireless Local Area Networks

Abstract

The medium access control (MAC) technique of standard WLANs, called the distributed coordination function (DCF), is carrier sense multiple access based on collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. It has a two way handshaking technique for packet transmission and also defines an additional four way handshaking technique called RTS/CTS mechanism, which is used to reduce the hidden terminal problem. The RTS/CTS frames carry the information of the packet length to be transmitted which can be read by any listening stations, to update a network allocation vector (NAV) about the information of the period of time in which the channel is busy. In this paper a method is proposed called the table driven technique (which has two parts called table driven DCF and table driven RTS/CTS) which is similar to the standard DCF (IEEE802.11) and RTS/CTS (IEEE802.11) system without having the exponential backoff. In this technique users use the optimum transmission probability by estimating the number of stations from the traffic conditions in a sliding window fashion one period at a time, thereby increasing the throughput compared to the standard DCF (IEEE802.11) and RTS/CTS (IEEE802.11) mechanism while maintaining the same fairness and the delay performance.