Analytical Model for Expected Packet Delay Evaluation in IEEE 802.11e

IEEE 802.11e has been released to provide Quality of Service (QoS) support for Wireless LAN. The Call Admission Control (CAC) reference scheme in HCF Controlled Channel Access (HCCA) supports only Constant Bit Rate (CBR) traffic. In this paper, a queueing analytical model for evaluating the expected packet delay of Variable Bit Rate (VBR) has been proposed. The numerical results show that regular acceptance method cannot guarantee the QoS. The paper also shows that accepting a VBR flow with a small amount over mean data rate should be able to handle the problem without degradation of accepted flows.