Madge Networks 802.11b Instrukcja Użytkownika Pobierz pdf (Strona 34)

PCF: Point Coordination Function

• The base station polls the other stations asking if they

have any frames to transmit, and co-ordinates

transmissions, avoiding collisions :

– This allows base station to allow some high

priority/time-bound applications to gain access to the

channel

– In PCF mode : the base station broadcasts a beacon

frame 10 to 100 times per second, providing system

parameters, and giving opportunities to the prioritized

stations to sign up.

– In between (prioritized transmissions), the station can

switch to DCF and allow other nodes to continue

transmission (assuming there is sufficient gap

between the prioritized transmissions)

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Madge Networks 802.11b Instrukcja Użytkownika Strona 34