The 6 GHz Wi-Fi Momentum Continues – FCC Announces Conditional Approval For Thirteen AFC Providers

David Coleman Director, Wireless Networking at the Office of the CTO Published 4 Nov 2022

The Federal Communications Commission (FCC) regulates communications within the United States as well as communications to and from the United States. Established by the Communications Act of 1934, the FCC is responsible for regulating interstate and international communications by radio, television, wire, satellite, and cable. The FCC regulates the radio frequencies (RF) that are used for these communications. The FCC has jurisdiction over the 50 states, the District of Columbia, and U.S. possessions. Most countries also have governing spectrum regulatory agencies that function similarly to the FCC.

The FCC and the respective controlling agencies in other countries typically regulate two categories of wireless communications: licensed spectrum and unlicensed spectrum. The difference is that unlicensed users can skip the license application procedures before installing a wireless system. Both licensed and unlicensed communications are typically regulated in the following five areas:

  • Bandwidth
  • Maximum power of the intentional radiator (IR)
  • Maximum equivalent isotropically radiated power (EIRP)
  • Use (indoor and/or outdoor)
  • Spectrum sharing rules

This week, very big news comes from the Office of Engineering and Technology (OET), the engineering arm of the FCC. The OET has conditionally approved thirteen proposed automated frequency coordination (AFC) database systems to finalize development for operations in the 6 GHz band and prepare for the testing phase.

FCC Chairwoman, Jessica Rosenworcel, stated “American businesses and households rely on Wi-Fi for work, school, access to healthcare, and connecting with friends and family. We are moving forward on our plan to open doors for next generation, faster, better Wi-Fi – including Wi-Fi 6E and laying the groundwork for Wi-Fi 7. This is good news and real progress.”

The FCC defines two major types of classifications for 6 GHz Wi-Fi devices with different transmit power rules: low power indoor (LPI) and standard power (SP) devices. The rules are very different. For example, LPI access points are limited to indoor locations, have an integrated antenna, and cannot use a weatherized enclosure. LPI devices use lower power and cannot be used outdoors. The FCC has determined that abiding by indoor power restrictions will not interfere with any incumbent services. As a result, the entire 6 GHz band is effectively available for indoor Wi-Fi in the United States, as depicted in Figure 1.

Figure 1 – 1200 MHz of 6 GHz frequency space for lower power indoor (LPI) devices

To date, all the Wi-Fi 6E APs and clients we have been using are LPI devices. However, the FCC does define another device class of standard power Wi-Fi devices for unlicensed outdoor and indoor communications in the UNII-5 and UNII-7 bands of the 6 GHz frequency. The U-NII-6 and U-NII-8 bands are already licensed for mobile satellite services and fixed satellite services (FSS) used in the broadcast and cable industries. Therefore, these two bands will be unavailable for outdoor Wi-Fi.

Figure 2 – UNNI-5 and UNII-7 bands in 6 GHz for Standard Power devices

This week’s announcement from the FCC signals that very soon, we should also be able to use standard power Wi-Fi devices, which have the capability of much higher transmit power. Standard power APs can also have detachable antennas and use a weatherized enclosure.

However, the FCC also imposes spectrum management restrictions to protect licensed incumbent fixed services in the UNII-5 and UNII-7 bands. Spectrum management is accomplished using automated frequency coordination (AFC). Think of AFC as a proactive method to mitigate interference with existing incumbents.

An AFC system will use geolocation databases to manage real-time frequency assignments to protect incumbent operations from RF interference. Before transmitting, a standard-power AP is required to obtain a list of permissible frequencies or a list of prohibited frequencies on which it cannot transmit, from an AFC system. The geographic coordinates of the AP should be determined by GPS or a similarly reliable method before checking in with the AFC system.

For example, you might want to deploy an outdoor standard power AP in Brookhaven, Georgia. Using either GPS or another method, you determine that the latitude of the AP is 33.865105 N, longitude is 84.336594 W, and the elevation is 304 meters. The AP would then use automated mechanisms to register its coordinates with an FCC-approved AFC system provider. The AP’s antenna height is also taken into consideration. The database of the AFC system provider automatically checks for possible interference with any incumbents. The AFC system provider determines the exclusion zones where standard power APs might cause harmful interference to incumbent links in the U-NII-5 and U-NII-7 bands. As shown in Figure 3, if an incumbent fixed service (FS) is nearby, a three-dimensional AFC protection contour is enforced on the standard- power Wi-Fi AP.

Figure 3 – Automated Frequency Coordination

An AFC system provider calculates a protection area around every incumbent fixed service (FS) receiver using licensee data in the FCC’s Universal Licensing System (ULS). The AFC system provider uses incumbent protection contours that account for a standard power AP’s geolocation, power, and other variables to determine which channels are permissible for the AP to transmit. In simpler words, the AP may not be allowed to transmit or may be required to lower its power well below 36 dBm EIRP to avoid interference with the incumbent. If there are no nearby incumbents in the area, the AP can transmit. AFC will be essential in urban areas and large cities where there are numerous incumbents.

As previously stated, the FCC has conditionally approved thirteen proposed AFCdatabase systems to finalize development for operations in the 6 GHz band and prepare for the testing phase. These include Broadcom, Comsearch, Federated Wireless, Google, Key Bridge Wireless, Kyrio, Nokia innovations, Plume Design, Qualcomm, Red Technologies, Sony Group, Wireless Broadband Alliance (WBA), and the Wi-Fi Alliance. All thirteen organizations will continue to develop their Automatic Frequency Control (AFC) systems. The next step in the approval process will involve testing to verify that they operate per FCC rules. Testing protocols are still under development, but more information will be provided in future releases. Detailed information from the FCC is available in this document.

This announcement from the FCC is big news. Standard power 6 GHz APs and AFC discussions are often centered around outdoor-use deployments such as stadiums. We need 6 GHz Wi-Fi outdoors, but please understand that there will also be many use cases for standard power 6 GHz Wi-Fi indoors. In the coming months, I promise to offer more blogs about the business aspects of 6 GHz standard power and the technical aspects of automated frequency coordination.

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