Wireless Netw (2007) 13:335–349 DOI 10.1007/s11276-006-7529-7 QoS Mechanisms for the MAC Protocol of IEEE 802.11 WLANs∗

Abstract There are two essential ingredients in order for any telecommunications system to be able to provide Quality-of-Service (QoS) guarantees: connection admission control (CAC) and service differentiation. In wireless local area net-works (WLANs), it is essential to carry out these functions at the MAC level. The original version of IEEE 802.11 medium access control (MAC) protocol for WLANs does not include either function. The IEEE 802.11e draft standard includes new features to facilitate and promote the provision of QoS guarantees, but no specific mechanisms are defined in the protocol to avoid over saturating the medium (via CAC) or to decide how to assign the available resources (via service differentiation through scheduling). This paper introduces specific mechanisms for both admission control and service differentiation into the IEEE 802.11 MAC protocol. The main contributions of this work are a novel CAC algorithm for leaky-bucket constrained traffic streams, an original frame scheduling mechanism referred to as DM-SCFQ, and a sim-ulation study of the performance of a WLAN including these features