What does PCF stand for in 802.11 terminology?

• A. Packet Control Field
• B. Point Coordination Function
• C. Physical Control Function
• D. Protocol Coordination Framework

Answer: (B)

PCF stands for Point Coordination Function. It’s a centralized, polling-based way to manage access to the wireless medium in 802.11. A Point Coordinator, typically the access point in an infrastructure network, overtakes control for a period called the Contention-Free Period and polls stations to grant them transmission opportunities one by one. This reduces collisions and provides more predictable access for time-sensitive data. The channel time is organized into a superframe that alternates between the CFP (where polling happens) and a contention period for devices to contend as in the usual CSMA/CA method. PCF is optional and not as widely used as the standard DCF, with QoS needs often addressed by later enhancements. The other terms listed aren’t the official 802.11 meaning for PCF.