AT&T, cable industry signal interest in launching LTE into shared 3.5 GHz band, likely for 5G

AT&T and CableLabs, the non-profit R&D company for the cable industry, both announced they will join the CBRS Alliance, a group formed earlier this year to develop LTE technologies for the 3.5 GHz band.

The news signals interest by both AT&T and CableLabs’ cable partners – which include heavyweights such as Comcast and Charter, as well as smaller cable companies – in deploying LTE technologies into the 150 MHz of spectrum that the FCC freed up last year in the 3.5 GHz band for both licensed and unlicensed usage.

“For LTE-based solutions in the shared CBRS band to be successful, we need a wide range of ecosystem partners, infrastructure, equipment and network providers, to work together closely,” Michael Peeters, vice president of Innovation Portfolio at Nokia and president of the CBRS Alliance, said in a release announcing that AT&T and CableLabs were joining the association. “We are thrilled to welcome all the new members to the CBRS Alliance and look forward to working together to provide solutions toward in-building and outdoor cellular coverage.”

AT&T has previously signaled interest in the 3.5 GHz band. Indeed, last month AT&T Laboratories asked the FCC for an experimental license so that its engineers can conduct tests on multiple new 5G radio systems with integrated adaptive antennas in the 3.5 GHz range. The tests are to take place in Cumming, Georgia, just outside of Atlanta.

AT&T’s interest in the 3.5 GHz band for 5G underscores the notion that 5G will be deployed into a variety of bands, particularly those above the standard cellular bands at 2.5 GHz and below. AT&T has been testing 5G services in a range of bands including in the 15 GHz and 28 GHz bands.

However, the 3.5 GHz isn’t like other spectrum bands. The FCC released the spectrum in 2015 with the understanding that it would be shared among licensed and unlicensed users via a spectrum-sharing scenario similar to the one used within TV white spaces spectrum bands.

Specifically, the FCC hopes to implement a Spectrum Access System (SAS) in the 3.5 GHz band – the agency is now in the process of hammering that SAS out now, which will make it possible to share spectrum where it hasn't been before. Google and Federated Wireless are often fingered as interested in handling SAS coordination and database administration, a key element for a spectrum sharing system.

LTE and spectrum sharing in the 3.5 GHz band also will allow private enterprises, venues and fixed operators, for example, to autonomously deploy high-quality in-building LTE networks into which all mobile network subscribers can roam. That’s part of the CBRS Alliance’s goal, and likely a reason CableLabs and its cable partners are signaling their interest in the alliance.

The situation could potentially result in Comcast building LTE networks in 3.5 GHz spectrum that would then be available to the likes of Verizon and AT&T for roaming – though to be clear, Comcast hasn’t made any announcements along these lines, and is generally tight-lipped when it comes to its wireless network deployment plans.

AT&T and CableLabs join a number of other high-profile companies in the CBRS Alliance, but AT&T is the only major Tier 1 operator to join the group. The CBRS Alliance was initially formed in February by six companies – Access Technologies (Alphabet/Google), Federated Wireless, Intel, Nokia, Qualcomm and Ruckus Wireless (now part of Brocade) – with the belief that “access to LTE-based solutions in the US 3.5 GHz frequency band will be a critical tool to meet rapidly expanding wireless data demands.”

AT&T and CableLabs aren’t the only new members of the CBRS Alliance, however. Accelleran, Airspan Networks, American Tower Corp., Baicells, Ericsson, ExteNet Systems, Nsight, Ranzure Networks, Rise Broadband and ZTE USA also joined the group.