A Dynamic Admission Control Scheme for QoS Supporting in IEEE 802.11e EDCA

With the successful development of IEEE 802.11 based wireless LAN(WLAN), the IEEE 802.11e enhanced distributed channel access (EDCA) is proposed to support QoS of applications. However, EDCA can not fully satisfied the QoS requirements of real-time applications, because of the shared channel and potential collisions. Thus, admission control is necessary for QoS guarantee in WLAN. In this paper, a traffic model is introduced to transfer unsaturated condition into saturated condition and an analysis model is set up to get the QoS parameters such as delay and packet loss rate; then, a dynamic admission control schemes is proposed based on the delay analysis model with the aim to guarantee the QoS of existing users and handoff users. Practical scenarios of voice over IP(VoIP) and data combined system with handoff are simulated to test the efficiency of our admission control schemes. Simulation results show QoS requirements of high priority voice users are well guaranteed while the data users fully use the remained bandwidth with the proposed admission control scheme.