DoD agrees to spectrum sharing paradigm in 37GHzDoD agrees to spectrum sharing paradigm in 37GHz

US military officials are moving forward with a plan to share spectrum in the lower 37GHz band with commercial 5G operators.

The development is noteworthy considering the ongoing debate over the much more valuable lower 3GHz band and how that spectrum might be shared between federal users and commercial wireless network operators like AT&T and Verizon. The DoD has been resistant to sharing lower 3GHz spectrum due to its existing systems in the band.

That debate, over the lower 3GHz band, has been going on for years, and it is contentious enough to have played a major role in the loss of the FCC's spectrum auction authority.

However, it's not clear how the 37GHz proceeding might affect debates about other spectrum bands like the lower 3GHz band. After all, the new 37GHz sharing proposal – announced by the NTIA and the US Department of Defense (DoD) – arrives in the waning days of the Biden administration. There are growing indications that the incoming Trump administration might be more willing to wrest spectrum away from federal users like the US military in order to distribute it to commercial 5G network operators under an exclusive spectrum licensing scenario – thereby forgoing the need for spectrum sharing.

"With Republicans taking control of the Senate, Sen. Ted Cruz will take the reins as Chairman of the Senate Commerce Committee. Sen. Cruz's top priorities are expected to include advancing legislation to free up spectrum for commercial use, such as the Spectrum Pipeline Act," wrote a group of lawyers from Akin Gump Strauss Hauer & Feld, LLP, an international law firm that's based in Washington, DC.

Cruz's Spectrum Pipeline Act focuses on exclusive spectrum licenses instead of sharing.

The 37GHz plan

In a new 31-page report, the NTIA and the DoD offered spectrum sharing recommendations for federal and non-federal users in the lower 37GHz band. The NTIA is the government agency that handles federal usage of spectrum. The FCC handles commercial spectrum usage.

"The FCC, NTIA and DoD began discussions in 2020 on the details of a coordination mechanism. These discussions resulted in a draft sharing framework, based on first-in user rights," the NTIA wrote in a release.

In its report, the NTIA outlined a detailed, two-phase sharing process for the band:

"The first phase would use simple propagation models to determine whether there are overlapping contours and permit operations to proceed in the absence of any overlap," the NTIA wrote. "The second phase would apply in the event of overlap between a proposed site registration and an existing site already registered in the database and would require the parties to exchange more detailed data and attempt to coordinate their operations."

Next the FCC would have to implement the NTIA's sharing recommendations.

The comments

That two-phase sharing approach has been mostly embraced by US companies in the 5G industry, including cable company Charter Communications and fixed wireless provider Starry.

"AT&T believes that the lower 37GHz band is a promising candidate band to explore for dynamic spectrum sharing. Its technical characteristics, combined with existing operations both in and adjacent to the band, lend themselves to a 'clean slate' approach where new spectrum sharing methodologies can be tested. However, as the commission develops a sharing framework from this band it must consider lessons from past spectrum sharing regimes and ensure productive and timely information-sharing to ensure that spectrum is rapidly and efficiently put to use," the operator told the FCC in a recent filing.

Verizon too argued that a two-phase sharing scenario represented a "reasonable" approach to opening the lower 37GHz band to commercial operations.

And Verizon's opinion on the matter is noteworthy considering the company is widely viewed as one of the world's biggest 5G supporters of mmWave spectrum. Indeed, in its filing, Verizon said it's using other portions of the 37GHz band for fixed wireless access (FWA) services, including to deliver Internet connections to multiple dwelling units (MDUs) like apartment buildings.

"Verizon also uses millimeter-wave spectrum to support distributed antenna system deployments indoors. For example, concertgoers and attendees of other events who want to livestream video, post pictures, and upload other content online to share their experiences are often able to do so because of the capacity gains afforded by large channels of millimeter-wave spectrum Verizon has deployed in large event venues," Verizon wrote. "The immediately adjacent lower 37GHz band could provide similar capabilities to increase capacity for fixed and mobile 5G services."

The value of mmWave

To be clear, the lower 37GHz band may no longer be of much value to the 5G industry. 

Verizon, T-Mobile, AT&T and others spent billions of dollars in the early days of 5G on millimeter wave (mmWave) spectrum licenses like those in the lower 37GHz band. But the value of those licenses appears to be rapidly declining.

For example, UScellular recently cut the value of its unsold mmWave spectrum licenses in half as part of its ongoing sell-off. Specifically, the company recorded a $136 million impairment on its mmWave holdings, dropping the value of those spectrum licenses from around $300 million to just $161 million.

And T-Mobile has gone so far as to relinquish some of its mmWave spectrum holdings. T-Mobile has not filed a comment in the FCC's lower 37GHz sharing proceeding.