Wireless Multimedia Extensions

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Wireless Multimedia Extensions (WME), also known as Wi-Fi Multimedia (WMM) is a Wi-Fi Alliance interoperability certification, based on the IEEE 802.11e draft standard. It provides basic Quality of service (QoS) features to IEEE 802.11 networks. WMM prioritizes traffic according to four AC (Access Categories) - voice, video, best effort, and background. However, it does not provide guaranteed throughput. It is suitable for simple applications that require QoS, such as Voice over IP (VoIP) on Wi-Fi phones.

[edit] Power Save Certification

The Wi-Fi Alliance has added Power Save Certification to the WMM specification. Power Save uses mechanisms from 802.11e and legacy 802.11 to save power (for battery powered equipment) and fine-tune power consumption. The certification provides an indication that the certified product is targeted for power critical applications like hand-phones and portable power devices. The underlying concept of WMM PowerSave is that the STA (station) triggers the release of buffered data from the AP by sending an uplink data frame. Upon receipt of such a data (trigger) frame the access point releases previously buffered data stored in each of its queues. Queues may be configured to be trigger enabled, i.e. a receipt of a data frame corresponding to the queue acts as trigger, and delivery enabled, i.e. data stored at those queues will be released upon receipt of a frame. Queues refer to the 4 ACs defined for WMM.