Siemens IEEE802.11 - Manual (Page 49)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 49 © Siemens, 2002
TIM
TIM-Interval
Time-axis
Busy Medium
Tx operation
AP activity
TIM TIM TIM DTIM DTIM
DTIM interval
PS Station
Broadcast
PS-Poll
Broadcast
Power Management Procedure
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