Adaptive Frequency Agility (AFA) is a technique used by radio transmitters to avoid transmission in channels that are already occupied. The radio transmitter periodically monitors its local radio environment and notes channels that are occupied. Based on this information the transmitters selects an operating frequency that is not yet used to avoid interference.
AFA can be very useful if a frequency band is shared among a large group of users or if the band has to be shared with another service which has a higher priority and therefore may not be be hindered.
AFA is usually combined with Listen Before Talk (LBT), which means that the transmitter listens to its radio environment before the transmission starts to be sure to operate in a free channel.