Issue Brief

Protecting 6 GHz Spectrum Usage by Public Power from Interference

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Electric utilities typically own and operate their own communications systems (wireline and wireless) for mission-critical operations throughout the electric system. These private communications networks are designed to remotely control transmission, generation, and distribution assets to ensure the safe and reliable delivery of power to homes, businesses, and communities. Many electric utilities, including public power utilities, rely on the 6 gigahertz (GHz) band of spectrum for wireless communications to operate critical electric infrastructure. Currently, the Federal Communications Commission (FCC or Commission) has proposed a rule to allow the operation of unlicensed devices in this band. The American Public Power Association (APPA or Association) has strong concerns with the Commission’s proposed rule, which if adopted, could threaten the reliability of utility communications monitoring and controlling key utility infrastructure. The Association believes the FCC needs to conduct rigorous, real-word testing of technology to prevent interference to licensed utility operations in the band before allowing unlicensed devices to operate in the 6 GHz band.


The 6 GHz frequency band, also referred to as “mid-band spectrum,” spans approximately 1,200 MHz of frequency band from 5.9 GHz through 7.1 GHz. Electric utilities and other critical infrastructure sectors use this band for critical communications using microwave networks. Many utility licensees moved into the 6 GHz band in the 1990s after being required by the FCC to leave the 2 GHz band, which was being reallocated for personal communication and mobile satellite services. Utilities use microwave networks for fixed point-to-point communications because the technology allows large amounts of data to reliably travel long distances. These networks are used to support real-time operations, including supervisory control and data acquisition (SCADA) systems used to monitor and control generating units, transmission lines, and substation equipment, as well as system protection, and voice communications between utility personnel in the field during natural disasters and other emergencies. The attributes that make the 6 GHz band well suited for critical utility communications also make it susceptible to interference. Until very recently, no spectrum sharing was allowed in the band. But with mounting pressure by large technology companies to open more bands of spectrum for unlicensed uses and federal policies that direct the National

Telecommunications and Information Administration (NTIA) and FCC to facilitate spectrum sharing where possible, electric utilities with critical communications networks in the 6 GHz band now face the real threat that spectrum sharing in the 6 GHz band will be allowed. Large numbers of unlicensed devices operating the band are likely to cause interference. While spectrum sharing has worked in some bands with little impact on incumbent operators in those bands, there is a real concern spectrum sharing could cause interference to communications networks operating in the 6 GHz band due to its attributes. Electric utilities are subject to mandatory reliability standards issued by the North American Electric Reliability Corporation (NERC) and enforced by the Federal Energy Regulatory Commission (FERC). They rely on their communications systems to ensure their compliance with these reliability standards. Any delay or degradation of communications signals on communication systems used by electric utilities in the 6 GHz band could lead to the disruption of power delivery and/or threaten the safety of workers and customers. Thus, utility communications must not experience harmful interference from unlicensed devices in the 6 GHz band and must maintain communications reliability to ensure the safe, reliable, and secure delivery of electric power and compliance with the FERC/NERC reliability standards.

Regulatory Action

In 2016, the FCC proposed granting a waiver to a startup company (Higher Ground, LLC) that would permit operation of a nationwide mobile network in the 6 GHz band. That application was met with overwhelming opposition by incumbent license holders and users concerned about the impact of interference on operations. Despite almost unanimous opposition, the FCC approved the waiver, allowing Higher Ground to operate 50,000 mobile devices that would support various “Internet of Things (IoT)” applications and be managed and operated through a spectrum database. In granting the waiver, it appears the Commission was persuaded by Higher Ground that unlicensed operations could occur in the band without causing interference to incumbent licensees’ operations. The waiver was approved even though the company never worked with licensees or tested its mitigation technology to ensure it would not cause interference to licensed operations in the band.1

In October 2018, the FCC issued a Notice of Proposed Rulemaking (NPRM) to open the 6 GHz band to unlicensed spectrum sharing. The FCC stated in the NPRM, “proposed rules will allow a valuable spectrum resource to be more intensively used to benefit consumers while allowing the existing licensed uses of the 6 GHz band to continue uninterrupted.” To address interference concerns, the FCC proposed use of an “automated frequency coordination (AFC)” system to mitigate any potential interference (a suggestion made by technology companies seeking unlicensed use of the band). In February 2019, APPA and other major utility trade associations filed joint comments urging the FCC to “not allow unlicensed operations in the 6 GHz band because…the potential for interference is unreasonably high and therefore likely to present significant adverse impact[s] to critical infrastructure communications….” This could “put at risk the safety of life, health, and property that incumbent licensees help to protect.” The reply comments noted the efficacy of AFC is unsupported by evidence or experience, with no field testing having been conducted. One month later, APPA and other utility trade associations filed joint reply comments reiterating their opposition to opening the band and concerns that the Commission is not properly weighing or addressing uncertainty about the efficacy of using AFC to prevent interference in the 6 GHz band.

In response to critical infrastructure industry concerns, other regulatory agencies weighed in with the FCC. On September 3, 2019, Bruce Walker, Assistant Secretary of the Office of Electricity at the Department of Energy (DOE), sent a letter to NTIA and the FCC expressing his concerns with the NPRM’s plan to rely on untested AFC. Assistant Secretary Walker cited an example of a similar system that was used in the 5.8 GHz band that did not work. DOE asked that adequate testing and safeguards be in place before making any changes in the band and offered the assistance of the National Laboratories. More recently, on December 18, 2019, FERC sent a letter to the FCC asking it to consider requests made by electric utilities and state regulators for additional testing of the AFC system prior to moving forward. Commissioners noted the cross-dependencies between communications and bulk power system operations and noted concerns were expressed at its last reliability technical conference on the possible impacts of unlicensed operations in the band on electric reliability.

Congressional Action

Congress has expressed concerns with the FCC’s proposal to open the 6 GHz band to unlicensed use numerous times. On April 1, 2019, Senator John Kennedy (R-LA) sent a letter to FCC Chairman Ajit Pai urging him to ensure that license holders in the 6 GHz band are protected from any potential interference. Senator Kennedy, who is chairman of the Senate Appropriations Committee’s Subcommittee on Financial Services and General Government, subsequently included language in the subcommittee’s fiscal year 2020 appropriations bill, stating that it “expects [the FCC] to ensure its plan does not result in harmful interference to incumbent users or impact critical infrastructure communications systems. The Committee is particularly concerned about the potential effects on reliability of the electric transmission and distribution system.”

In June 2019, Senate Energy & Natural Resources Chair­man Lisa Murkowski (R-AK) also sent a letter to Chairman Pai asking questions regarding the FCC’s proposal and whether it considered the impacts it could have on electric grid reliability, if the Commission has consulted FERC or NERC during the proceeding, and whether it has visited with electric utilities to see how their communications networks operate. In Janu­ary 2020, Chairman Pai responded to Senator Murkowski’s letter with a short one-page letter that asserts the Commission “will protect incumbent systems in the 6 GHz band, including electric utilities, from harmful interference.” The letter did not respond to all of the questions posed by Senator Murkowski, nor did it provide any real details on the FCC’s interactions with FERC on this proceeding.

On April 30, a bipartisan group of 13 members of California’s congressional delegation sent a letter to the FCC encouraging it to carefully craft technical specifications to ensure protection of utilities and other critical infrastructure owners from harmful interreference. Most recently, a bipartisan group of 12 senators, led by Senator James Risch (R-ID) and Senator Mazie Hirono (D-HI), sent a letter to the FCC asking that it ensure protection against harmful interference by “requir[ing] sufficient, rigorous testing of the proposed mitigation measure before any final decision is made.”

American Public Power Association Position

APPA supports the FCC’s goals of expanded access and usage of spectrum bands. However, the Association strongly opposes opening the 6 GHz band to unlicensed users due to the unacceptable risk of interference to mission-critical electric utility communications networks used for SCADA systems that monitor and control transmission, generation units, and substations. There is no evidence that the AFC technology will perform as promised and prohibit interference. Moreover, there are no current reasonable alternative bands for utilities to migrate to if interference is not mitigated, while alternatives and ability to handle interference do exist in other bands for those unlicensed users currently seeking access to the 6 GHz band.

1. Higher Ground never began operations. Its current status is unknown.