AT&T is the first U.S. mobile operator to deploy dynamic spectrum sharing (DSS), a technology that it claims to have developed in AT&T Labs before pushing it into 5G standards.

The technology is only available on three devices in parts of AT&T’s network in north Texas, but the company said it will continue to deploy the technology around the country as it adds more 5G markets. “DSS plays an important role in our journey to nationwide 5G, which we expect to hit this summer,” an AT&T spokesperson told SDxCentral.

AT&T recently tempered some expectations for 5G adoption this year, due to the COVID-19 crisis, but maintains that it will reach nationwide 5G availability this summer. AT&T’s 5G network operating on 850 MHz spectrum current covers 120 million people.

“The timing is informed by where we have markets with higher loads on LTE, which would have a great impact of carving for 5G,” the spokesperson explained. “In situations where this would be the case, we will use DSS to balance traffic between 4G and 5G.”

DSS allows operators to use the same spectrum channels for 4G LTE and 5G on a demand-generated and automatic basis, rather than allocating entire chunks of that spectrum for a single generation of cellular connectivity.

“The performance of DSS will depend in large part on how frequently traffic demand changes and the granularity of the resource allocations,” explained Igal Elbaz, AT&T’s SVP of wireless technology, in a blog post.

“DSS is an important stepping stone on our path to nationwide 5G. The software-based technology allows us to bypass the process of refarming spectrum in the near term, which ultimately means a smoother transition and expedited 5G adoption,” he wrote.

AT&T declined to say which spectrum bands are gaining DSS in this initial phase, but added that the technology is not limited to a specific band and the operator plans to use the technology as needed on different parts of its network. 

DSS has widespread interest among operators, but some are leaning on it more heavily than others, particularly as domestic carriers work against self-imposed deadlines to assemble a nationwide 5G footprint before the end of the year.

T-Mobile US lit up its nationwide 5G network running on 600 MHz spectrum in late 2019 without the aid of DSS. Neville Ray, president of technology at the operator, has more recently dissed the technology as a corrosive capacity hog that is arriving later than expected. T-Mobile US still plans to use the technology, but it hasn’t placed a timeline on that goal.

Ericsson made its version of the technology commercially available in February, and Nokia released its DSS software in April. The Finnish vendor doesn’t expect DSS to deliver meaningful performance gains on standalone 5G networks until 2021. AT&T declined the name the vendors involved in its DSS deployment. 

Among the three nationwide carriers, DSS is most critical for Verizon’s 5G strategy. The operator plans to have 5G mobile service commercially available in 60 cities before the end of the year, and DSS, which it plans to deploy later this year, will be the final piece of that nationwide footprint.