Scheduling Scheme for Variable Bit Rate Traffic in IEEE 802.11e Wireless LANs

IEEE 802.11e hybrid coordination function (HCF) provides quality of service (QoS) in 802.11 networks, which proposed a simple HCF scheduler to take the QoS requirements into account. However, such scheduling algorithm is only efficient for constant bit rate (CBR) traffic. A simple and effective scheduling scheme is proposed to support both variable bit rate (VBR) traffic and CBR traffic in this paper, which employs the traffic load information of the amount of buffered frames in each traffic stream (TS) queue sent by stations (STAs) in real-time piggybacked way to allocate accurate transmission opportunities (TXOPs) duration to satisfy the pending traffic QoS. Simulation results prove the proposed scheme makes the STAs achieve lower transmission delay and better channel utilization