Abstract: The quality-of-service (QoS) support for wireless
LANs has been a hot research topic during the past few years. In this paper, two QoS provisioning mechanisms are proposed for the employment in 802.11e EDCA MAC scheme. First, the proposed call
admission control mechanism can not only guarantee the QoS for the higher priority existing connections but also provide the minimum reserved bandwidth for traffic flows with lower priority. In addition, the adaptive contention window adjustment mechanism can adjust the
maximum and minimum contention window size dynamically according to the existing connection number of each AC. The collision
probability as well as the packet delay will thus be reduced effectively.
Performance results via simulations have revealed the enhanced QoS property achieved by employing these two mechanisms.