Given: As defined in the 802.11 specification, legacy Power Save requires an inefficient back-andforth frame exchange process. Due to this inefficiency, many WLAN device implementations use a
variation of 802.11 Power Save to accomplish the same function.
What non-standard power save behavior is used by most Wi-Fi devices in actual
Client devices ignore the TIM field and automatically send PS-Poll frames after every beacon.
After each beacon, the AP attempts to empty its frame buffer by sending Wake-on-WLAN
frames to wake each dozing client.
Request-to-Send and Clear-to-Send frame exchanges are used to trigger the delivery of
The Beacon interval is changed from the default 100 time units to 10 or less time units.
Clients send null data frames to the AP and switch the power management bit from 1 to 0 to
receive queued data.
Stations send a CTS-to-self frame to the AP with a very long duration period so they can
receive all of their buffered data at once.