Federal spectrum regulators at the FCC have come under increasing fire over concerns that 5G in C-band spectrum might interfere with aircraft radio altimeters.

Indeed, that issue has ballooned into a major national debate, with executives in the airline industry claiming a "catastrophic failure" in regulations, while wireless technology experts lament the government's failure to "uphold its statutory responsibilities."

But the C-band brouhaha isn't the only high-stakes battle over spectrum interference at the FCC. The agency is facing another regulatory battle over the 6GHz band – one that apparently has nuclear ramifications.

"NextEra subsidiary FPL utilizes the 6GHz band to provide network diversity for operations across its 30,000 square miles plus service area, including a number of large nuclear and natural gas generation facilities: Turkey Point (nuclear and natural gas), St. Lucie (nuclear), Martin (natural gas and solar), and the Okeechobee Clean Energy Center (natural gas, planned solar and hydrogen)," the company told the FCC. "Communication services utilizing 6GHz frequencies at these locations include network voice and data communications and plant control communications. These communications services are critical to ensuring required communications with the Nuclear Regulatory Commission (NRC) and Florida state government agencies and safe operations for these facilities."

Utilities assemble

NextEra is one of several major utility companies that piled onto a last-ditch effort by several utility trade associations to block commercial operations in the 6GHz band. The FCC voted last year to open up that band to low-power unlicensed operations including Wi-Fi. And though the agency did look at whether such commercial operations would interfere with existing utility networks in the band, it didn't look hard enough, according to the utility companies.

"The results of the real-world interference tests fundamentally call into question the basis for the commission's rules," the groups – including the Utilities Technology Council and the American Public Power Association – argued in a December filing at the FCC.

Specifically, the utility associations said the FCC relied too heavily on research conducted by CableLabs into whether new commercial operations in the 6GHz band would affect existing, incumbent operations in the band, including those owned by utility companies. The associations pointed to a study released in June by utility provider Southern Company that found such commercial operations would in fact affect these users.

"This new testing confirmed that FCC-certified unlicensed LPI [low-power indoor] devices will cause harmful interference to licensed fixed microwave systems, including those used to monitor and protect the electrical grid and for public safety operations," according to the associations.

Figure 1: According to the Utilities Technology Council, utility providers use communications networks for a number of applications. Click here for a larger version of this image.
(Source: Utilities Technology Council)

Indeed, the report from Southern Company warned that commercial, low-power operations in the 6GHz band, such as Wi-Fi, could potentially affect utility operations up to five miles away.

"These unlicensed 6GHz LPI devices pose an imminent risk of harmful interference to licensed operations that would cause irreparable harm," the associations argued. "The public interest would be served by granting a temporary stay [halting sales of 6GHz devices] because doing so will protect against interference that threatens the safe, reliable, and secure delivery of essential services to the public provided by electric, gas, and water utilities as well as by public safety, broadcast television, telecommunications, and broadband service providers. The time to act is now."

Back and forth, again

To be clear, this isn't the first time such concerns have been raised. AT&T and others have warned the FCC that its plan to free up the 6GHz band for operations like Wi-Fi could affect everything from 5G microwave backhaul to radio astronomy.

And proponents of Wi-Fi in the 6GHz band, including companies like Cisco and Apple, have urged the FCC to reject such interference concerns.

Nonetheless, the concerted push by the nation's utility companies – ranging from FirstEnergy to Evergy Companies to Idaho Power Company to PacifiCorp to Ameren Services Company to Xcel Energy to Dominion Energy Services – signals their ongoing concerns over the matter.

Further, there's evidence that a last-ditch, Hail Mary regulatory push against the FCC can be effective. Specifically, the FCC last year voted on rules to auction off the C-band for commercial 5G operations. But the airline industry in recent months mounted a major, 11th-hour campaign to halt AT&T and Verizon's 5G launches in the band over concerns such operations might affect aircraft radio altimeters.

How the FCC's newly appointed chairwoman, Jessica Rosenworcel, might address the situation remains to be seen. But it again underscores widespread complaints of government mismanagement of spectrum resources during the Trump administration and, now, during the Biden administration.

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano