Siemens IEEE802.11 Tutorial page 49

Power Management Procedure
Time-axis
TIM TIM
AP activity
PS Station
n
Stations wake up prior to an expected DTIM
(Delivery Traffic Indication Message).
n
If TIM indicates frame buffered
– station sends PS-Poll and stays awake to receive data
– else station sleeps again
n
Broadcast frames are also buffered in AP.
– all broadcasts/multicasts are buffered
– broadcasts/multicasts are only sent after DTIM.
– DTIM interval is a multiple of TIM interval
WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt
TIM-Interval
Busy Medium
DTIM
Broadcast
DTIM interval
TIM TIM
PS-Poll
DTIM
Broadcast
Tx operation
Page 49 © Siemens, 2002