T-Mobile eyes spectrum above 95 GHz for 5G backhaul

T-Mobile 5G
T-Mobile says the FCC should be mindful of the potential use of spectrum above 95 GHz for mobile service in the future. (FierceWireless)

It appears that the spectrum that some refer to as “way out there” will be well-suited to support T-Mobile's 5G backhaul.

Citing the FCC’s Spectrum Horizons rulemaking, the “uncarrier” says the spectrum bands above 95 GHz can support wide bandwidths—up to 5 GHz—which means they can carry high-bandwidth wireless traffic where installation of a fiber optic line is difficult. In total, it notes that the commission could make 36 gigahertz of spectrum in the 95-275 GHz range available for backhaul applications.

These bands have the ability to carry data over short ranges, and that makes them an ideal candidate for backhaul. In addition, these bands feature narrow beamwidths, so many links can coexist in the same geographical area because tighter beams are less likely to cause interference, the filing notes.

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T-Mobile points out that the commission is proposing service rules covering fixed use of the spectrum above 95 GHz available for licensing; most of that spectrum is also allocated for mobile operations. However, the commission proposes no mobile service rules for the spectrum, an approach that T-Mobile generally supports. 

But a lot can change in a few short years. The 24, 28 and 39 GHz bands were initially designated by the FCC for fixed operations, and now they’re seeing mobile use permitted and executed in those bands.

“In authorizing fixed use of the spectrum above 95 GHz, the Commission should therefore be mindful of the potential to use the spectrum for mobile service in the future,” the operator said.

T-Mobile also noted that converting spectrum for mobile use does not appear feasible at 70 and 80 GHz in part because of the proliferation of individual links throughout those bands. But T-Mobile generally supports the commission’s approach to using the 70/80/90 GHz band rules as a model for spectrum use above 95 GHz, although it wants the commission to modify antenna standards.

Interestingly, T-Mobile is also urging the commission to impose a performance reporting requirement at the end of the time permitted for construction of individual links. Citing a Fixed Wireless Communications Coalition proposal (PDF), the operator said it supports rules that would require licensees to certify that facilities associated with their site registrations and frequencies are actually in use.

T-Mobile’s suggestions are among many others the commission will consider as it contemplates rules for the spectrum above 95 GHz. In launching the proceeding, FCC Chairman Ajit Pai acknowledged that some people are skeptical that this spectrum can be used productively, but the skeptics have been proven wrong before. Some said the spectrum above 3 GHz wasn’t really useful for mobile communications, yet midband spectrum is very popular today—and millimeter wave licenses above 24 GHz have already drawn multibillion-dollar attention from the private sector on the secondary market.