Sniff and Embark Protocol for QoS Enhancement in Wireless LANs

The IEEE 802.11e standard defines the enhanced distributed coordination function (EDCF) to improve the quality of service (QoS) in a wireless local area network (WLAN). The EDCF is a CSMA/CA based protocol, where stations compete for the medium with prioritized contention parameters. Also defined in the 802.11e standard is the polling mode of the hybrid coordination function (HCF - Polling), which is a centralized QoS mechanism. The primary purpose of the 802.11e HCF is to decrease the average queuing delay. The EDCF fails to scale well at high loads due to increase in collisions, while the HCF Polling compromises on throughput to achieve lower delay and has the disadvantage of being centrally controlled. In this paper, we propose an adaptive sniffing based protocol (Sniff and Embark protocol) that works around the deficiencies of the IEEE 802.11e standard. The simulations show that Sniff and Embark protocol outperforms the EDCF in terms of providing higher throughput and lower average delay.