Simple and effective QoS schemes supporting VoIP traffic in IEEE 802.11 network

This thesis presents several simple and effective QoS schemes aimed to support VoIP in the IEEE 802.11 network. The proposed schemes are called dynamic backoff adjustment (DBA), high priority DCF (HP-DCF), adaptive DCF (ADCF) and direct priority DCF (DP-DCF). All four schemes utilize the contention mechanism and are compatible with the IEEE 802.11 standard. The first three schemes use dynamic adjustment approach to improve the delay of high-priority traffic in infrastructure network and the last schemes is designed for use in ad-hoc network. From the simulation results, the DBA scheme shows better bandwidth utilization over DCF and provides better differentiated service performance than EDCF. Whereas, the HP-DCF and AP schemes give better protection of the real-time traffic classes from the excessive best-effort traffic load in the infrastructure mode. Moreover, the DP-DCF also shows its ability in protecting the real-time traffic class in the ad-hoc environment.