DCF, PCF, HCF

Distributed coordination function (DCF) is the fundamental medium access control (MAC) technique of the IEEE 802.11-based WLAN standard (including Wi-Fi). DCF employs a carrier-sense multiple access with collision avoidance (CSMA/CA) with binary exponential backoff algorithm.
Point coordination function (PCD) is a media access control technique used in IEEE 802.11 based WLANs, including Wi-Fi. It resides in a point coordinator also known as access point, to coordinate the communication within the network. The AP waits for PIFS duration rather than DIFS duration to grasp the channel.
The 802.11e Quality of Service facility defines a new coordination function termed HCF which is only used in QBSS but implemented in all QSTA. The HCF combines functions of the DCF and PCF with some enhanced specific mechanisms and frame subtypes to support the transfer of Quality of Service data across a WiFi network.

#DCF #PCF #HCF #CSMA #CSMACA #CSMACD #wifi #wireless #CWNA