Monday, April 1, 2013

Hybrid power save in 802.11 (difference from UAPSD)


Do both legacy power save and WMM power save. This allows some classes of traffic to be trigger enabled and some other classes to be supported by legacy PS. This could possibly allow the client to make its PS scheme more effective. E.g. consider this it could tell the AP to make VO traffic trigger enabled and the rest supported by legacy. So when it is critical, the client always sends trigger for VO class and gets appropriate frames. When the client sees TIM bit set and decides it can take some other traffic, it sends PS-POLL to which the AP appropriately responds with highest priority of non-trigger enabled WMM class frames.

Note that in response to the PS-POLL the AP should only send non-trigger enabled classes of traffic to the client.