Siemens IEEE802.11 Manuel d'utilisateur télécharger pdf (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

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Siemens IEEE802.11 Manuel d'utilisateur Page 44