FERC last week urged the Federal Communications Commission to conduct additional testing to ensure automated frequency coordination (AFC) will protect utilities’ use of the 6 GHz spectrum band, which the FCC is considering opening to unlicensed users.

In a letter to FCC Chair Ajit Pai, the commission noted the concerns of electric utilities, which use the spectrum (5,925 to 7,125 MHz) 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 wireline networks are not available.

The issue was the subject of a panel during FERC’s annual technical conference on reliability in June. (See Utilities Warn of Encroachment on Communications Band.)

In proposing the use of the spectrum by unlicensed users, FCC cited estimates that North American mobile traffic, including unlicensed Wi-Fi devices, grew 44% in 2016 and is projected to grow nearly 35% annually through 2021. AFC would use 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.

“We ask that you consider the implications for electric reliability and closely review the rulemaking comments that discuss the potential impacts of the proposal on electric reliability,” the commissioners wrote. “Should the proposed rule be adopted, we strongly urge you to consider requests from electric utilities and state regulators for additional testing of the AFC system prior to implementation. We understand the complexity of assessing the cross-dependencies between areas of critical infrastructure and would be pleased to offer technical assistance through FERC staff if it would be helpful.”

— Rich Heidorn Jr.