Abstract— The IEEE 802.11e standard has recently been ratified. This standard provides Quality-of-Service (QoS) guarantees in the Medium Access Control (MAC) layer of 802.11 Wireless Local Area Networks (WLANs). In other words, the 802.11e standard updates the MAC layer of the former 802.11 standard for QoS. In particular, the Enhanced Distributed Channel Access (EDCA) function of 802.11e is an enhancement of the Distributed