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AT&T: mobile 5G will rely on small cells
by Martha DeGrasse
AT&T plans to launch mobile 5G this year in 12 U.S. cities, and the carrier says the service will rely on small cells deployed closer to the ground than the tower top radios that support LTE. AT&T’s first round of mobile 5G will use millimeter wave spectrum, which offers higher capacity rates than low-band spectrum but does not propagate over large distances. That means radios need to closer together than they are in LTE deployments.
“Millimeter wave is more associated with small cell-like ranges and heights,” said AT&T’s Hank Kafka, VP of network architecture. “It can be on telephone poles or light poles or building rooftops or on towers, but generally if you’re putting it on towers it’s at a lower height than you would put a high-powered macrocell, because of the propagation characteristics.”
Kafka said this year’s 5G rollout will require significant zoning and permitting negotiations in the target cities, but he declined to name those cities. So far AT&T has announced 23 cities that are getting its 5G Evolution infrastructure, which the company describes as “the foundation for mobile 5G.” Those cities are Atlanta; Austin; Boston; Bridgeport, Connecticut; Buffalo, New York; Chicago; Fresno, CA; Greenville, South Carolina; Hartford, Connecticut; Houston; Indianapolis; Los Angeles; Louisville; Memphis; Nashville; New Orleans; Oklahoma City; Pittsburgh; San Antonio; San Diego; San Francisco; Tulsa, Oklahoma and Sacramento, California.
AT&T has recently expanded trials for Project AirGig, but Kafka said the utility-pole mounted radios and antennas will not be part of this year’s mobile 5G launch. He said the carrier’s AirGig launch will occur at a later date.
AT&T’s deployment of small cells to support mobile 5G will be largely independent of another major infrastructure initiative slated for this year, the buildout of the 700 MHz spectrum AT&T was awarded to support FirstNet. Kafka said that in some instances, tower crews might be able to add 5G equipment near the base of the tower at the same time they add 700 MHz radios to the top. But the synergies between the two deployments are limited.
“Where appropriate we’re always going to try and get as much synergy as we can … but there’s a difference between dealing with small cell sites and dealing with macro sites,” Kafka said.
Does that mean AT&T will send crews back to the towers if it deploys 5G in lower-band spectrum down the road? Not necessarily. Many of the newest LTE radios may support 5G at a later date once the software is available.
“You’ll find that a lot of radios that suppliers are putting out now are going to be upgradeable to support 5G,” Kafka said. “Some of the radios we’re deploying now do have that capability in the hardware.”
Will AT&T use 3.5 GHz spectrum for 5G?
Mobile network operators in Europe and Asia plan to deploy 5G in the 3.5 GHz spectrum bands, but will U.S. operators have the same opportunity? Cable network operators, fixed wireless providers, neutral host providers and even private companies are all expected to be buyers of CBRS spectrum, depending on how the FCC auctions play out.
The latest CBRS market study from iGR Research provides an explanation of how the CBRS licensing scheme works and how the technical elements of the new band work. This report includes a forecast of the total number of CBRS nodes expected to be deployed in the U.S. through 2022. The forecasted number of nodes is categorized by Outdoor WISP, Outdoor nonWISP, Inside Commercial, and Inside Residential.