What is AFC?
Automated Frequency Coordination (AFC) is a cloud database service that controls standard-power Wi-Fi in the 6 GHz band. Before a standard-power access point transmits, it reports its location to an AFC system, which works out which 6 GHz channels and power levels it can use there without interfering with licensed users of the band. Those licensed users are mainly fixed point-to-point microwave links run by utilities, public safety agencies and carriers.
AFC is a regulatory requirement, not a performance feature. In the United States the FCC sets the rules and approves the companies that operate AFC systems.
How it works
- The access point determines its location, commonly with a built-in GPS receiver, along with its antenna height and how precise the location is.
- It sends that information to an AFC system, normally through the vendor's cloud service or controller.
- The AFC system checks the protected licensed links near that location and returns the channels the access point may use and the maximum power for each.
- The access point stays within that list and checks in again at least once a day. If it can't check in, it must stop standard-power operation after a short grace period.
Low-power indoor vs. standard power
In the United States (FCC), 6 GHz access points fall into two main classes:
| Low-power indoor (LPI) | Standard power | |
|---|---|---|
| Where | Indoors only | Indoors or outdoors |
| Needs AFC | No | Yes |
| US sub-bands | UNII-5, 6, 7 and 8 | UNII-5 and UNII-7 only |
| Transmit power | Lower | Much higher, for more range |
LPI access points must be indoor models: they can't be weatherproof or battery powered, so walls and roofs contain most of their signal. That is why they don't need AFC. Standard power isn't allowed in UNII-6 and UNII-8 because those sub-bands carry mobile licensed services, such as TV broadcast links, whose positions a location database can't track.
Other countries set their own 6 GHz rules. The European Union, for example, opened only the lower part of the band, for low-power devices, so AFC doesn't apply there.
AFC vs. DFS
Both protect licensed users, in different ways. DFS on 5 GHz makes the access point listen for radar itself and leave a channel when it hears it. AFC on 6 GHz gets permission in advance from a database, based on where the access point is. A standard-power access point doesn't scan for microwave links; it simply uses the channels AFC allows.
For the CompTIA A+ exam
Core 1 (220-1201) objective 2.2 covers the 6 GHz frequency band and the regulations that apply to wireless channels. AFC isn't named in the objectives or the acronym list, so treat it as background: know that 6 GHz has low-power indoor and standard-power modes, and that standard power depends on an AFC database check.