Siemens IEEE802.11 Tutorial page 44

Timing Synchronization Function (TSF)
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All stations maintain a local timer.
– Used for Power Management
• All station timers in BSS are synchronized
– Used for Point Coordination Timing
• TSF Timer used to predict start of Contention Free burst
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Timing Synchronization Function (TSF)
– keeps timers from all stations in synch
– AP controls timing in infrastructure networks
– distributed function for Independent BSS
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Timing conveyed by periodic Beacon transmissions
– Beacons contain Timestamp for the entire BSS
– Timestamp from Beacons used to calibrate local clocks
– not required to hear every Beacon to stay in synch
– Beacons contain other management information
• also used for Power Management, Roaming
WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 44 © Siemens, 2002