WMM is an abbreviation for Wi-Fi Multimedia. It is a Wi-Fi Alliance interoperability certification, based on the IEEE 802.11e standard. It provides basic Quality of service (QoS) features to IEEE 802.11 networks.
WMM prioritizes traffic according to four Access Categories (AC) – best effort, background, video and voice (AC_BE, AC_BK, AC_VI and AC_VO).
WMM does not provide guaranteed throughput. It is suitable for applications that require QoS, such as Voice over IP (VoIP) on Wi-Fi phones.
The priorities of each of the WMM categories are:
AC_BE (Best Effort): Medium priority queue, medium throughput and delay. Most traditional IP data is sent to this queue.
AC_BK (Background): Lowest priority queue, high throughput. Bulk data that requires maximum throughput and is not time-sensitive is sent to this queue (FTP data, for example):
AC_VI (Video): High priority queue, minimum delay. Time-sensitive data such as Video and other streaming media are automatically sent to this queue.
AC_VO (Voice): Highest priority queue, minimum delay. Time-sensitive data such as Voice over IP (VoIP) is automatically sent to this queue.