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Power management procedure – Siemens IEEE802.11 User Manual

Page 49

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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