Date Added: Feb 2012
Quality of Service (QoS) is the ability to guarantee a certain level of performance to a data flow i.e., guaranteeing required bit rate, delay, etc. IEEE 802.11 a/b/g networks do not provide QoS differentiation among multimedia traffic. QoS provisioning is one of the essential features in IEEE 802.11e. It uses Enhanced Distributed Channel Access (EDCA) which is a contention-based channel access mode to provide QoS differentiation. EDCA works with four Access Categories (AC). Differentiation of Access Categories are achieved by differentiating the Arbitration Inter-Frame Space (AIFS), the initial Contention Window size (CWmin), the maximum Contention Window size (CWmax) and the Transmission OPportunity (TXOP).