White Papers
Wi-Fi CERTIFIED™ for WMM® (2004)
Multimedia applications in a Wi-Fi network require Quality of Service (QoS) functionality.
QoS enables Wi-Fi access points to prioritize traffic and optimizes the way shared
network resources are allocated among different applications. Without QoS, all
applications running on different devices have equal opportunity to transmit data frames.
That works well for data traffic from applications such as web browsers, file transfers, or
email, but it is inadequate for multimedia applications. Voice over Internet Protocol
(VoIP), video streaming, and interactive gaming are highly sensitive to latency increases
and throughput reductions, and require QoS.
To meet this need, the Wi-Fi Alliance started interoperability certification for WMM (Wi-Fi
Multimedia) as a profile of the upcoming IEEE 802.11e QoS extensions for 802.11
networks. WMM prioritizes traffic demands from different applications and extends
Wi-Fi's high quality end-user experience from data connectivity to voice, music, and
video applications under a wide variety of environment and traffic conditions. WMM
defines four access categories (voice, video, best effort, and background) that are used
to prioritize traffic so that these applications have access to the necessary network
resources. Additionally, WMM-enabled Wi-Fi networks concurrently support legacy
devices that lack WMM functionality. The WMM best effort access category and legacy
devices transmit with the same priority.
The Wi-Fi CERTIFIED™ for WMM program tests interoperability with WMM and
interoperability with existing Wi-Fi devices. The certification program is available to all
new Wi-Fi-enabled devices. Existing Wi-Fi devices can receive a software upgrade.
Wi-Fi CERTIFIED™ for WMM is optional, as not all clients need QoS capabilities. The Wi-
Fi Alliance has worked closely with the industry and standards bodies to ensure wide
adoption of WMM in new CE devices and new multimedia applications.
To take advantage of WWM functionality in a Wi-Fi network, three requirements have to
be met: (1) the access point is Wi-Fi CERTIFIED™ for WMM and has WMM enabled; (2)
the client (device) that the application is running on must be Wi-Fi CERTIFIED™ for WMM; and (3) the source application supports WMM.