AFA (Adaptive Frequency Agility)
AFA is the ability to switch automatically to another channel when a channel is found occupied or corrupted. It is generally used together with a listen-before-talk method: listening tells you the channel is busy, and AFA decides where to move. It provides a clear advantage under interference compared with a fixed single-channel system.
AFA keeps a channel list and monitors availability status. If a channel is persistently found busy or faulty, it is temporarily dropped from the list; it is reinstated when conditions change.
- Relation to LBT: listening measures the channel status, and AFA changes channel according to that measurement. Together they produce consistent channel access behaviour.
- Difference from FHSS: in frequency hopping the channel change happens continuously according to a predetermined pattern; in AFA the change is triggered by the situation.
- Result: when a new interference source enters the facility, the system repositions itself and no user intervention is needed.
Conditions on an industrial site are not fixed: a new wireless device is installed, an inverter is commissioned, transmission starts at a neighbouring facility. Adaptive behaviour is the very feature that keeps a link that worked well during installation working months later.
Context in which this term is used: 433 MHz or 2.4 GHz?