A Priority Based Differentiation for Contention Mechanism in Legacy DCF Method

Under the current scenario, many applications, across various domains of real world, are utilizing the Wireless LAN (WLAN) technology. With its growing usage, the requirement for QoS in WLAN has also gained significance. The most prevalent WLAN standard IEEE 802.11 does not provide QoS. In order to render service differentiation in the existing IEEE 802.11 scheme, we have presented a priority based differentiation scheme. The proposed scheme is implemented during the contention process of the existing DCF method. The contention window is divided with respect to various priority levels. The priority levels are decided on the basis of the data sensed by the station. The higher priority levels contend with a lower random back-off value and thus, are favored during transmission. Although, IEEE802.11e, the enhanced version of IEEE802.11, does provide QoS, our scheme is easier to implement on the existing legacy DCF systems. The proposed scheme modifies only the contention window and not parameters like Inter Frame Space, unlike IEEE 802.11e. We have presented the analysis of this suggested prioritization strategy on the basis of average delay, average throughput and packet received to packet sent ratio through the simulation result.