- Operators are already kicking the tires on the 4 GHz band
- Verizon’s application came just weeks after NTIA announced plans to study the 4.4 GHz band for potential full-power commercial licensed use
- The 4 GHz band isn’t without its challenges: Federal incumbents still loom large as the band is used by defense, homeland security and public safety systems
The 4 GHz band is all the rage these days. Once considered too high for anything suitable for 5G, it appears to be just about perfect for 6G.
Scratch that. Despite dueling studies released last week that seem to suggest the 4 GHz band – which ranges from 4.4-4.94 GHz – is the bees’ knees for 6G, operators like Verizon and T-Mobile are asking for permission to conduct tests in the band. Hence, they're not declaring it "perfect" quite yet.
Specifically, Verizon is asking the Federal Communications Commission (FCC) for an experimental authorization to use the 4.8-4.9 GHz band in and around its lab in Los Angeles to test Ericsson software and hardware in a non-commercial environment.
Samsung is also listed as a manufacturer of “various” equipment to be tested.
Verizon is asking for a one-year grant. The tests are intended to work as part of a private network that’s not connected to commercial operators.
T-Mobile tests at HQ
Meanwhile, T-Mobile USA is asking for experimental authorization for two years to conduct tests in the 4.8-4.9 GHz band at six sites in and around its headquarters in Bellevue, Washington.
T-Mobile didn’t name any vendors in its application but said the tests would include up to six temporary fixed base stations installed at six locations, three of which would be located at T-Mobile’s headquarters and three of which would be at T-Mobile’s lab campus. Each base station is expected to operate with up to six experimental mobile devices.
Who’s on first? Verizon, it appears
Fierce was curious about the timing of these applications and turned to engineering consultant Steve Crowley, who flagged them on X.com, for his take.
He said Verizon’s September 4 application appeared to be the first from a major operator to conduct tests in the band since the National Telecommunications and Information Administration's (NTIA) July 31 announcement that the Trump Administration had cleared plans to study the 4.4 GHz band for full-power commercial licensed use.
T-Mobile’s two applications were filed on September 17; separately, it’s also seeking permission for tests at 2.7 GHz.
A cursive search did not turn up any recent 4 GHz test applications from AT&T, but Crowley also said his search wasn’t exhaustive. (By the way, he noted that non-6G work on these types of spectrum bands goes back decades. For example, permission was granted back in the day to use the 2400-5400 MHz band to test ultra-wideband technology. So a “who’s on first” query may be moot.)
As for the differences between the Verizon and T-Mobile tests, there are some obvious ones, like T-Mobile enlisting the use of six base station sites versus one for Verizon. That may mean T-Mobile is experimenting with handovers of multiple mobile devices, he noted.
CTIA highlights 4 GHz
In a statement last week, CTIA said the 4 GHz band is a “key opportunity” and “a cornerstone of the spectrum pipeline identified by the Administration and Congress,” alongside upper C-Band, 2.7 GHz and 7 GHz.
The 4 GHz band is currently used by federal agencies for various systems related to defense, homeland security and public safety, all of which need to be protected.
However, it looks like their use of the spectrum isn’t that intense, i.e., there’s a lot of room for these systems to be moved into smaller slices of spectrum, retuned to different channels or relocated to comparable spectrum, according to a study by Accenture that was commissioned by CTIA.
Making the case for sharing
Around the same time CTIA came out with its study, another group, called Spectrum for the Future – which includes cable companies like Comcast and Charter Communications – argued that spectrum sharing could put more of the 4.4 GHz band to commercial use sooner – and at a lower cost – while preserving federal operations.
The study by Valo Analytica noted that the 4.4 GHz band is one of the most heavily used federal bands ever considered for repurposing, supporting uses like military communications, drone systems, border security and wildfire monitoring.
A shared spectrum approach, rather than a traditional high-power exclusive approach that requires relocating or reconfiguring those systems, could be preferable, according to the Valo analysis.
Basically, Valo is urging the NTIA to evaluate sharing as a core strategy for the 4.4 GHz band as it begins its study rather than considering it as an afterthought.
However it shakes out, operators are clearly getting ready for the next tranche of spectrum potentially coming down the pipeline. How it all washes out in the end – that’s worth watching.
Read more Fierce stories about 4 GHz and 6G:
NTIA tees up 4.4 GHz band for 6G study