Opening 6 GHz band will harm utilities, other critical infrastructure, study shows

Several trade groups, including the American Public Power Association and the Utilities Technology Council, on Monday released a report warning of the risks if the Federal Communications Commission (FCC) opens up the 6 GHz bandwidth to unlicensed users.

The 6 GHz band of the radio spectrum is well suited and widely used by a broad array of industries responsible for critical infrastructure such as electric, gas and water utilities, railroads, and wireless carriers, as well as by public safety and law enforcement officials. Those industries rely on the 6 GHz band to operate their equipment, and it is their main source of communication during emergencies and disasters.

Unimpeded use of the 6 GHz band is “paramount” to the continued operation and safety of critical infrastructure, according to the report. “This study demonstrates the real-world risk from the current proposal to the broad cross-section of the nation’s critical infrastructure and public safety users that depend daily on the 6 GHz band for essential and mission-critical communications,” Sharla Artz, UTC’s senior vice president of government and external relations, said in an email. “We are filing this report to continue our dialogue with the FCC and other stakeholders and we look forward to additional discussion.”

The report, Impact of Proposed Wi-Fi Operations on Microwave Links at 6 GHz, was commissioned by the Edison Electric Institute, the American Gas Association, the American Public Power Association, the American Water Works Association, the National Rural Electric Cooperative Association, the Nuclear Energy Institute, and the Utilities Technology Council.

The critical infrastructure industries parties say they commissioned the report to provide a real-world analysis of the potential impact of unlicensed use of the 6 GHz band.

The study detailed inference impact on the 520 microwave sites in operation in the Houston metropolitan area, as well as impact of indoor and outdoor Wi-Fi deployments in the area.

The study looked at interference from both residential and outdoor Wi-Fi access points and for Wi-Fi adjacent channel emissions and found that, as currently proposed in the FCC rule, unlicensed wireless networks in the 6 GHz band would cause “all the point-to-point links in the Houston area to experience unacceptable levels of interference” that could cause operational problems.

The study used Houston because its flat terrain simplifies signal loss issues and provides a realistic indication of interference levels in a major market. In addition, the Houston area is host to a wide range of critical infrastructure interests, including energy, transportation, and telecommunication companies, as well as utility and municipal infrastructure.

The report also noted that the choice of the Houston metropolitan area is not a “worst-case geographic area.” The interference impact on a much more densely populated area, such as Manhattan in New York City, could be 100 times higher.

In December 2018, the FCC issued a Notice of Proposed Rulemaking on Unlicensed Use of the 6 GHz Band that would allow unlicensed devices to use the 6 GHz band alongside licensed users in critical infrastructure industries (CII). The comment period on the issue remains open until the FCC puts the item on its agenda for a final decision, which is expected by the end of the first quarter of 2020.

Technology companies, including Apple, Broadcom, Cisco, Facebook, and Qualcomm, are pushing for unlicensed access to 6 GHz because, they say, internet traffic on the unlicensed spectrum is growing exponentially. They argue that opening 6 GHz for Wi-Fi would expand internet access for a larger swath of the population and encourage innovation. They also argue that any potential interference can be handled by a technology known as Automatic Frequency Coordination (AFC).

The critical infrastructure industries argue there has been no testing of the AFC technology and that not all Wi-Fi companies would want to use the technology.

“Unlike other studies submitted in the docket, the CII User Study is based on actual, real-world user data, and not theoretical or hypothetical assumptions concerning the operations of incumbent fixed microwave systems in the band,” the report stated.

In a November letter, 12 senators urged the FCC to ensure that critical infrastructure industries are protected from “harmful interference before taking further action” and noted that, unlike proponents of the rule, CII incumbents do not have alternatives to the 6 GHz band.

Also in November, the National Association of Regulatory Utility Commissioners issued a resolution recommending that the FCC modify its proposal unless and until it has tested and proven that its Automatic Frequency Coordination system works as intended to protect license holders, including utility and other critical infrastructure industry systems, and “it is demonstrated that unlicensed operations will not cause harmful interference to license holders as determined by the FCC.”