Distributed Coordination Function

Distributed Coordination Function ( DCF) is a mechanism in WLAN ( IEEE 802.11 ) to the non- deterministic access by multiple participants is regulated to the wireless network. The DCF mechanism supports voice and multimedia applications in WLANs in terms of performance requirements.

In WLANs based on IEEE 802.11 is communicatively to a shared -media procedure with CSMA / CA, with no quality of service features (QoS ) can be guaranteed. To ensure the quality of service as the transmission rate, the maturity, the data loss rate, etc. different coordination functions have been developed, including DCF. In an occupied radio network, a user waits from at least the specified in the 802.11 standard time DIFS and a random waiting time before it checks whether the wireless network is busy or if he can send. In addition to the DIFS time, there are shorter waiting times, SIFS and PIFS.

Since the DCF - function is not sufficiently met the requirements for the quality of service ( QoS), has been developed the hybrid coordination function (HCF) for 802.11e and implements contained therein DCF function as revised EDCF.