What is Automated Frequency Coordination (AFC)?

What is an Automated Frequency Coordination? Why does Wi-Fi 6/7 need to use this?

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Nov 5, 2022

Automated Frequency Coordination (AFC) is a spectrum use coordination system that consists of a registered database of all the bands in use by various types of radio frequency services in a particular area. It is used by Wi-Fi access points (APs), especially those that operate in the newly allocated 6 GHz band (5.925–7.125 GHz).

When the FCC opened up the 6 GHz band for unlicensed Wi-Fi operation, it received worldwide support because of the new possibilities it opened up for Wi-Fi. This new frequency band brought with it the ability to deliver faster connectivity speeds and improved capacity when compared to both 2.4 GHz and 5 GHz Wi-Fi. 6 GHz was first made available for Wi-Fi 6E operation, but now the upcoming Wi-Fi 7 will also rely heavily on the newest spectrum band. However, there are several other technologies that already operate in this band. These services include fixed satellite services (FSS) used in the broadcast and cable industries that already have a license for 6 GHz channels. Hence, to ensure new unlicensed users of Wi-Fi do not impact the current services, some significant restrictions were included for Wi-Fi in this band.

With the goal of avoiding potential interference with existing 6 GHz occupants, the FCC defines two types of device classifications with very different transmit power rules. Low power APs for indoor Wi-Fi and standard power APs for indoor/outdoor Wi-Fi. The low power APs, as the name implies, have reduced power levels since they are only used indoors. Any building walls can further attenuate their signals, making any potential interference with existing 6 GHz users very unlikely. But the outdoor or standard power APs have a higher chance of interfering with existing 6 GHz users in the area. Hence to ensure these standard power APs do not impact the current services the FCC created a way to coordinate the spectrum use to avoid interference issues - the AFC system.

The spectrum use coordination system is not new – similar systems exist to support white space (White-Fi) and CBRS wireless operation. The basic concept behind such a coordination system like AFC is that a new wireless device (access point) will consult a registered database to confirm its operation will not impact a registered user. Standard power APs will compulsorily use an AFC service to protect occupant 6 GHz operations from RF interference. A company that provides AFC service is called an AFC provider.

The AFC provider will contain a database of existing 6 GHz operators, including geolocation, frequencies, power levels, antenna coverage, etc. The AFC database can be built from the existing FCC database in which users are required to register their transmitters. Outdoor/standard power 6 GHz Wi-Fi may be deployed only when such an AFC service is in place for an area.

Before transmitting, a standard power AP can consult a local AFC system to validate frequency operation via the following protocol:

  • Communication can be directly from AP to AFC or more likely via a proxy, such as a network management system
  • Just like the incumbent 6 GHz transmitter, the AP must provide all information about its location, coverage, and planned frequencies/power to be used
  • The AFC will either approve the usage request or provide alternatives, available channels, etc. Only then can the 6 GHz access point start operation

This process is still in development, so the actual approval and specific rules are yet to be determined. AFC systems are expected to go operational by 2023 starting with Wi-Fi 6E systems and then will be further developed for Wi-Fi 7.