The Federal Communications Commission on Thursday agreed to open a portion of the 6-GHz band for unlicensed use over the objections of utilities, which fear their communications in the spectrum could be disrupted.

The FCC said its ruling “will usher in Wi-Fi 6, the next generation of Wi-Fi, and play a major role in the growth of the Internet of Things,” noting Wi-Fi 6 will be more than two-and-a-half times faster than the current standard. It said it will nearly quintuple the amount of spectrum available for Wi-Fi and improve rural connectivity (Docket 18-295).

But the Utilities Technology Council blasted the move, saying the FCC had failed to balance protection of critical communications in its desire to be innovative.

“Opening the 6-GHz band can be done in such a way that can both unleash the new innovations the FCC and others hope for while also protecting the CII [critical-infrastructure industries] systems already in the band. Doing so would take time, additional study and stronger protections for incumbent systems,” the UTC said in a statement. “Today, the FCC appears to have decided on taking a much riskier approach that does not control low-power indoor operations using AFC [automated frequency coordination systems]. Nor does the FCC order provide additional testing to prevent interference from occurring or enforcement processes to resolve interference that does occur.”

“While we support the goal of using spectrum more efficiently, today’s decision by the FCC means there will be no field testing or AFC mechanism in place to protect incumbent users from interference by indoor low-power devices,” said Phil Moeller, the Edison Electric Institute’s executive vice president for business operations and regulatory affairs. “EEI’s member companies remain committed to providing their customers with reliable and secure energy, and we will carefully monitor the band for interference to prevent any significant impacts to mission-critical communications systems.”

Electric utilities use the 6-GHz band for point-to-point microwave links providing communications with substations, fault sensors, two-way meters and service crews. It is also used to provide situational awareness in rural areas where wired networks are not available. Other critical infrastructure such as police and fire dispatch, railroads, and natural gas and oil pipelines also use the spectrum. (See Utilities Warn of Encroachment on Communications Band.)

The commission authorized indoor low-power operations over the full 1,200 MHz (5.925–7.125 GHz) and standard-power devices in 850 MHz of the 6-GHz band.

The FCC also issued a Further Notice of Proposed Rulemaking seeking comment on permitting very low-power devices to operate across the 6-GHz band to support high data rate applications such as wearable augmented-reality and virtual-reality devices. The notice also seeks comment on increasing the power at which low-power indoor access points can operate.

The commission said its order was critical to realizing its goal of “making broadband connectivity available to all Americans, especially those in rural and underserved areas.”

FCC Chairman Ajit Pai noted in a statement the importance of Wi-Fi during the COVID-19 pandemic.

“Sheltering in place would be a lot more difficult without Wi-Fi,” he said. “Of course, even before anyone had heard of COVID-19, Wi-Fi already carried more than half of the Internet’s traffic, and offloading mobile data traffic to Wi-Fi was vital to keeping our cellular networks from being overwhelmed. In a very real sense, Wi-Fi is the fabric that binds together all our digital devices.”

[NOTE: The commission’s order had not been posted as of press time Thursday evening.]

The FCC insists the AFC system will prevent standard power access points from operating where they could cause interference to existing services. But utilities say AFC — which uses a “database lookup scheme” to ensure that unlicensed users are not encroaching on an existing user’s priority access to the frequency in a specific area — should be required for low-power devices also.

‘Real-world’ Study

UTC, EEI, the American Gas Association, the American Public Power Association and the National Rural Electric Cooperative Association submitted a study to the FCC in January that looked at the impact of the proposed rule on 520 microwave sites and 2,325 point-to-point communications receivers in the nine-county Houston Metropolitan Statistical Area, chosen because its flat terrain simplified “propagation path loss issues.”

“The analysis clearly demonstrates that allowing unlicensed devices to operate in the 6-GHz band will render fixed point-to-point communications receivers serving critical infrastructure in [the] Houston MSA unreliable and unable to meet minimal performance objectives, specifically geographic coverage (i.e., long links), high bit rates, low latency and high reliability,” said the study, which was conducted by Roberson and Associates, a technology and management consulting company.

Utilities use the 6-GHz band because it allows microwave networks with multiple links to cover large areas with very low latency time delays, high bit rates and high reliability, with resilience to “rain fading.”

“Given the critical nature of the communications carried on the 6-GHz band, the public safety and CII networks operating in this band are built to extremely high standards of reliability — 99.999% or 99.9999% availability. These networks must also transmit with extremely low levels of latency — 20 milliseconds or less of roundtrip delay from one point to another over long distances. No other band has sufficient bandwidth with all key characteristics (large geographical distances, low latency time delays, high bit rates, high reliability) to permit reliable operations in large, dense metropolitan networks such as Houston,” the study said.

Millions, Billions

EEI noted in an April 15 letter to the FCC that “unlicensed advocates themselves predict the deployment and operation of millions if not billions of unlicensed devices in the band. The combination of this vast number of devices, the bandwidth of their operation, the duty cycle of their transmissions and that most will not be identifiable or controllable after sale make harmful interference a virtual certainty.”

Such interference, EEI said, “can lead to power outages, wildfires and other potential disasters.”

It said the commission should form a stakeholder group including utilities to respond to interference and that AFC should be more widely required.

But even AFC is not a panacea, the utilities’ study said. “AFC cannot control interference from indoor RLANs [radio local area networks] in central Houston without degenerating to complete exclusion of the entire U-NII-5 and U-NII-7” sub-bands, which comprises most of the 6-GHz band.