Chip Vendors Help Power Up 6GHz

Broadcom and Qualcomm will support a new automated-frequency-coordination (AFC) system to allow Wi-Fi and unlicensed 5G devices to use higher power in the 6GHz band, increasing performance and range.

Bob Wheeler

Radio spectrum is finite, so intelligent sharing is vital to faster wireless connections. Newly opened bands aren’t really new, as they generally have incumbent users that receive priority over unlicensed services. Such is the case with the 6GHz band, which the FCC opened for unlicensed use two years ago. At the time, the Wi-Fi industry heralded the new spectrum as enabling seven 160MHz-wide channels.

Scarcely publicized, however, was the fact that initial 6GHz systems could operate only at low power and indoors (LPI). The industry is pushing to undo this limitation in time for Wi-Fi 7 systems, which will also enable 320MHz channels in the new spectrum. Lifting the power limit extends range and increases data rates at any given distance.

To employ standard power levels (up to a maximum 36dBm EIRP) or to operate outdoors, unlicensed 6GHz systems require a new automated-frequency-coordination (AFC) system. Whereas dynamic frequency selection (DFS) in the 5GHz band simply listens for licensed radars to avoid interference, AFC will operate as a managed service with which the access point (AP) must communicate before enabling standard power. In the 6GHz band, the primary licensed incumbents are fixed-wireless microwave links.

Standard-power APs must support a secure connection to the AFC service over the Internet using a protocol such as TLS. The Wi-Fi Alliance developed an AFC system-to-device interface that specifies JSON objects transported over HTTPS. In this implementation, the device (AP) sends the AFC service a spectrum inquiry with desired channels or frequency ranges, minimum desired EIRP, and device-location data. The service responds with the available frequency ranges or channels as well as an expiration time and date, after which the availability is invalid.