User:Broodjekaas/IEEE 802.11aa

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IEEE 802.11aa is a wireless computer networking amendment of the IEEE 802.11 standard that aims to provide increased reliability and robustness for audio-video streaming when using 802.11 Wireless Local Area Networks (WLAN).

On January 27, 2012, draft 9 of 802.11aa completed its last sponsor ballot prior to editing by IEEE staff and publication. [1]. The TGaa task group started working on this amendment in May 2008, following approval of the task group on March 27, 2008 [2].

New technologies[edit]

IEEE 802.11aa amends the 802.11 MAC to add the following new features:

  • Overlapping Network Mitigation
  • Multiple video priority levels
  • Graceful degradation
  • Support for IEEE 802.1Qat Stream Reservation Protocol
  • More Reliable Multicast / Broadcast

Overlapping Network Mitigation[edit]

The Overlapping BSS feature of 802.11aa provides a mechanism for the co-operative sharing between Access Points that operate on the same channel.

Multiple video priority levels[edit]

IEEE 802.11 provides four EDCA access functions (EDCAF) that contend with each other to gain access to transmit frames. Each EDCAF has an associated queue of frames that are waiting to be transmitted. The 802.11aa amendment adds two addition queues (one for video, one for voice) that selected by the video and voice EDCAFs respectively. These extra queues are intended to allow there to be prioritisation between video streams and between voice streams.

Graceful degradation[edit]

IEEE 802.11aa adds a drop eligible indicator (DEI) to the MAC header of 802.11 frames. This indicator can be used by an 802.11 station to discard frames with the DEI bit set in preference to frames where the DEI bit is unset.

Support for IEEE 802.1Qat Stream_Reservation_Protocol[edit]

IEEE 802.11aa integrates the IEEE 802.1Qat Stream_Reservation_Protocol (SRP) with the TSPEC admission contol feature added by 802.11e (now part of the 802.11-2007 standard). This allows end-to-end reservations to be created between devices that support 802.11aa and other networking technologies that can support SRP such as IEEE_802.3.

More Reliable Multicast / Broadcast[edit]

The Group Addressed Transmission Service (GATS) allows selected group addressed frames to be re-transmitted to increase the probably of correct reception at stations receiving these group addresses.


  1. ^ "IEEE-SA SPONSOR BALLOTS AS RELATED TO IEEE 802.11 WG". IEEE 802.11 Working Group. 2012-02-19. 
  2. ^ "Official IEEE 802.11 Working Group Project Timelines". IEEE 802.11 Working Group. 2012-02-19. 

External links[edit]