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Wireless Multimedia Extensions , also known as Wi-Fi Multimedia , is a Wi-Fi Alliance interoperability certification, based on the IEEE 802.11e standard. It provides basic Quality of service features to IEEE 802.11 networks. WMM prioritizes traffic according to four Access Categories : voice , video , best effort , and background. However, it does not provide guaranteed throughput. It is suitable for well-defined applications that require QoS, such as Voice over IP on Wi-Fi phones.
WMM replaces the Wi-Fi DCF distributed coordination function for CSMA/CA wireless frame transmission with Enhanced Distributed Coordination Function. EDCF, according to version 1.1 of the WMM specifications by the Wi-Fi Alliance, defines Access Categories labels AC_VO, AC_VI, AC_BE, and AC_BK for the Enhanced Distributed Channel Access parameters that are used by a WMM-enabled station to control how long it sets its Transmission Opportunity , according to the information transmitted by the access point to the station. It is implemented for wireless QoS between RF media.