802.11e The IEEE standard (2005) for wireless LAN (WLAN) quality of service (QoS) based on access priority classes. 802.11e introduces a coordination function that provides a station with high priority traffic such as voice with more frequent network access than a station with low priority traffic such as e-mail. The station with the high priority traffic also is granted a longer transmit opportunity, or window, in which to transmit as many frames as possible. In all, 802.11e defines four access priority classes, which the Wi-Fi Alliance terms Wi-Fi MultiMedia Extensions (WMMs, or WMEs).Those classes are as follows: • Voice Priority, the highest level, is defined in support of low latency voice. • Video Priority, the second highest level, prioritizes video relative to other data traffic. One 802.11a/b channel can support three-to-four standard definition television (SDTV) datastreams or one high definition television (HDTV) datastream. 74570cintro.qxd 9/11/07 12:17 PM Page 14 |