Exploring Automatic Frequency Coordination (AFC) Technology for WI-FI 6GHz Field

In the following text, we will explore the impact of this situation and how the Federal Communications Commission (FCC) in the United States can help ensure fair and consistent coexistence of Wi Fi with other licensed and unlicensed radios through resolutions.

Existing licensed operators in the 6GHz frequency band

As shown in the figure below, the current players in the 6GHz frequency band include fixed wireless, fixed satellite, and mobile operators. To operate in this frequency band, these existing users have already paid licensing fees. Therefore, the FCC must take measures to protect their investments. Wi Fi 6E and Wi Fi 7 cover the entire UNII-5 to UNII-8 spectrum; Therefore, in the area where existing radio signals are located, certain requirements need to be met to ensure coexistence; This is the field where Automatic Frequency Coordination (AFC) plays a role.

To protect existing network operators within the 6GHz frequency band, unlicensed devices and any outdoor devices exceeding the power level specified by the Low Power Indoor (LPI) can only access the spectrum under the control of the AFC system. This will help reduce interference with existing services and increase the required spectrum for unlicensed innovative applications.

FCC and 6GHz frequency band regulations

In April 2020, the FCC unanimously voted to pass new rules for wireless operation in the 6GHz frequency band, opening up 1200MHz spectrum to unlicensed devices such as Wi Fi access points (APs). This decision has doubled the available bandwidth of Wi Fi, bringing more spectrum for backhaul, gaming, and scenarios such as higher data capacity, outdoor mesh networks, and dense outdoor deployments.

The opening of the 6GHz frequency band means that both indoor and outdoor Wi Fi access points (APs) can enjoy high-speed video streaming at home and in outdoor sports stadiums, parking lots, outdoor cafes, and other places.

The LPI mode AP used for indoor operation will take into account that building walls will cause a certain degree of signal reduction to equipment during operation, ensuring that it will not interfere with licensed existing equipment. In addition, the FCC has defined a standard power AFC control mode that can be authorized for indoor and outdoor operations. For unlicensed indoor low-power access points, this regulation provides an opportunity to expand capacity and performance for channels up to 320MHz.

The FCC regulations authorize two types of unlicensed operations in the 6GHz frequency band, as shown in the table below. The first type of equipment will be standard power access points using Automatic Frequency Coordination (AFC) in the UNII-5 and UNII-7 frequency bands; This will allow the use of unlicensed broadband in the 5GHz and 6GHz frequency bands. AFC will alleviate potential interference to existing fixed and mobile license service providers. Before the standard power AP starts operating in the 6GHz frequency band, it must first interact with the AFC system. We will discuss this issue in detail later in this article.

The power level used by client devices depends on the type of access point - either standard power or power specified by the LPI AP. The maximum power level depends on the location of use. When the client device is controlled by a standard power AP, it will be very close to the access point; And during transmission, only the AFC system can be used to determine frequencies that will not cause interference to the fixed microwave link.

Both regulations will optimize unlicensed Wi Fi access to 6GHz spectrum while protecting existing services.

Detailed Explanation of Automatic Frequency Coordination (AFC) Process System

The FCC regulates cross state and international communication of radio, television, cable, and satellite across the United States, and is responsible for enforcing and enforcing all communication laws and regulations. Fixed microwave systems have been required to register with the FCC, specifying their location and antenna height. This information can be obtained through the AFC system.

The AFC system will establish a restricted zone to prohibit the operation of unauthorized devices. For example, before the AP starts transmission, the standard power AP needs to obtain a list of frequencies allowed or prohibited for transmission from the AFC system. Thus, the AFC system will provide protection for the fixed service microwave link. (See the figure below)

The AFC system will help manage and eliminate any potential interference between APs and fixed and mobile microwave infrastructure systems; It can also protect the frequencies used by certain radio observatories.