Siemens IEEE802.11 - Manual (Page 44)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 44 © Siemens, 2002
Timing Synchronization Function (TSF)
n
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
n
Timing Synchronization Function (TSF)
– keeps timers from all stations in synch
– AP controls timing in infrastructure networks
– distributed function for Independent BSS
n
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