The Federal Communications Commission is considering an auction of additional midband airwaves as soon as October of this year, for 100 megahertz of spectrum at 3.45-3.55 GHz.
Acting Chairwoman Jessica Rosenworcel has begun circulating a proposal that the FCC will consider at its next meeting on March 17. Commissioner Brendan Carr has already indicated his support of the action, which will open up midband spectrum that is contiguous with the Citizens Broadband Radio Service.
“We need to deliver the 5G that the American people were promised. That means a 5G that is fast, secure, resilient, and—most importantly—available across the country. This important auction is a crucial step toward making that a reality. I hope my colleagues will join me in supporting this proposal,” Rosenworcel said in a statement.
The proposed new rules would allocate the 3.45-3.55 GHz spectrum band for flexible-use service, provide for coordination of federal and non-federal users and relocate non-federal radio-location use to 2.9-3.0 GHz and eventually end amateur use of 3.3-3.5 GHz. Congress passed legislation last year that required the FCC to auction the licenses by the end of this year; the Trump administration had expected the spectrum to be auctioned by December 2021, but it appears that could happen sooner.
“I am proud of the legwork the FCC and our partners across the federal government have put in to open up this 100 MHz of mid-band spectrum, and I am pleased that the Commission will now vote on the steps needed to auction off these airwaves this year,” said Commissioner Brendan Carr. “I look forward to reviewing the draft decision and working with my colleagues to ensure that it maximizes opportunities for 5G in the U.S., including by authorizing full power commercial operations.”
Interest in the band for sharing dates back to a 2010 ten-year plan to open up 500 megahertz of spectrum for commercial use, with renewed interest under a 2018 mandate to examine the possibility of spectrum-sharing in a broader range from 3.1-3.55 GHz. The National Telecommunications and Information Administration last year reported to Congress on the feasibility of sharing in the band, saying that the section of that spectrum between 3.45-3.55 GHz was identified as having “the highest probability of being able to accommodate sharing with commercial wireless services in a relatively short timeframe.”
The Department of Defense has already conducted a related 3450-3550 MHz Technical Study considered all federal systems (primarily radar systems) in the band, potential aggregate interference to those systems under two different hypothetical commercial deployments and three sets of power levels for each, including “both the relatively low-power operation currently permitted for commercial operations in the adjacent band above 3550 MHz and the higher power levels that industry representatives have indicated are optimal.” While commercial systems at 3.45-3.55 GHz would generate interference with the existing ones, the study found, it “nonetheless concludes that, with a transition of nationwide aeronautical systems to alternative frequencies, proper interference mitigation mechanisms, and further study, spectrum sharing may be technically feasible for all or portions of the 3450-3550 MHz sub-band, including at all the power levels analyzed.”
Additionally, a National Telecommunications and Information Administration report floated the idea of a federal Spectrum Access System-type approach called an Incumbent Informing Capability (IIC), rather than the commercial SAS strategy used in the CBRS band. NTIA said at the time that it suggested this approach “partly because industry-managed monitoring stations outside military installations are inherently problematic from an operational security perspective and many more would be required due to the large number of ground-based radar sites, and partly because there are unique technical challenges to monitoring airborne operations.”
In a letter to the FCC last week, the National Telecommunications and Information Administration said that it agrees that the “positive experiences and tools of the AWS-3 coordination” should be leveraged for 3.45 GHz, and it maintained that an IIIC could also be developed to facilitate federal and non-federal coordination.
Federated Wireless has gone on-record as opposing the development of a specific IIC function and instead proposed extending the rules of the neighboring CBRS band to 3.45-3.55 GHz. Jennifer McCarthy, VP of legal advocacy for Federated, has said that “Rather than developing yet another coordination approach between federal and commercial users that, based on real-world experience in other bands, is likely to take longer and be more costly to implement than initially anticipated, the CBRS sharing framework is well-established and can be leveraged immediately to enable spectrum access even as federal users begin their transition. Such CBRS rule changes would provide a wide range of benefits for 5G, including enabling wider channels, simpler device designs, and increased scale of equipment manufacturing, which will in turn lead to lower deployment costs and improved coverage across the combined bands.”
The NTIA letter last week specified 33 locations in 17 states where coordination with the military will be necessary, and also noted specifically that there are several radar manufacturing and integration facilities that need access to the 3.45 GHz spectrum for experimentation and testing for federal systems — and that they typically operate outdoors because of the size of the systems. It is critical for those facilities to retain access to the spectrum, NTIA said.
NTIA said that the listed locations would not be exclusion zones, but areas that need protection from interference by non-federal operations either indefinitely or periodically.