A MAC protocol with QoS guarantees for real-time traffics in wireless LANs

In this paper, a medium access control (MAC) technique for wireless LANs (WLANs) with quality of service (QoS) assurance is introduced, which is also compatible with the current WLAN standard IEEE 802.11. The proposed protocol called "enhanced black burst (EBB)" aims at improving the network performance for real-time variable bit rate traffic (VBR), and uses two types of contention mechanisms: one is based on Sobrinho and Krishnakumar\´s novel idea of using a jamming signal, which is called black burst (BB), to ensure that there is a unique winner for each contention. The other one, by modifying the binary backoff procedure in the original CSMA/CA protocol of IEEE 802.11 standard, gives relative priority level to different classes of traffics. The protocol has been implemented and tested using VINT network simulator 2 (NS2) under Red Hat Linux 7.2. The performance evaluation and comparison confirm the improved QoS features and multimedia support of EBB compared to BB and the Enhanced DCF proposed by the IEEE 802.11e task group.