Call Admission Control Based on Adaptive Physical Rate for EDCA in IEEE 802.11e WLAN System

IEEE 802.11e wireless LAN standard supports the call admission control (CAC) for the quality of service (QoS) traffic such as video and voice based on the medium time which means the bandwidth allocation normalized by the arrival time interval of corresponding traffic streams. IEEE 802.11e defines the medium time and its argument, MPDU exchange time which means the duration for the transmission of corresponding traffic stream. The task group (TGe) for 802.11e recommend the definition of MPDU exchange time by using the minimum transmission physical layer rate (PHY rate) without considering adaptive PHY rate to the wireless channel variations. In this paper, we propose new MPDU exchange time considering the adaptive PHY rate instead of fixed rate. The CAC with this proposed MPDU exchange time enhance the user capacity by about 45% maintaining the guarantee of QoS.