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AT&T gave its open RAN keys to Ericsson last year
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AT&T and Ericsson executives on a Connect (X) panel shared some information about their progress
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The world is pivoting to CU, DU and RU, according to a wireless engineering VP at AT&T
CONNECT(X) ATLANTA — AT&T’s decision last year to award Ericsson a $14 billion, five-year open Radio Access Network (RAN) contract initially sparked a lot more questions than answers.
Why choose Ericsson, whose reputation in open RAN was sketchy? How open is open RAN when one vendor is leading the charge? And will other operators follow AT&T’s lead and take a single-vendor approach to open RAN?
Not all but at least some of those questions were addressed during a Connect (X) panel starring AT&T, Ericsson and Dell, moderated by Patrick Lopez of Core Analytics.
Todd Zeiler, VP of Wireless Engineering at AT&T, shared this nugget: “If you take a picture of our network in X number of years … I think the word ‘cell site’ goes away. I think this pivots to a world of CU, DU, RU. Servers and access points.”
Indeed, much of the session dealt with elements related to the "U," to the point where Zeiler asked: “Anybody need any more Us?,” which generated chuckles from the audience. He was, of course, referring to centralized units (CU), distributed units (DU) and radio units (RU).
Open or not open
Boiling down the network topology, Lopez pointed out how much is coming from Ericsson: RUs, CUs and DUs, as well as service management and orchestration (SMO) and near-real time RIC. Dell supplies the servers, but rApps also are coming from Ericsson and third parties. In short, rApps are network automation tools.
Is that really open RAN when Ericsson is in charge of so much? Is AT&T looking at introducing more vendors per category?
Zeiler said it’s a fair question. Given that AT&T awarded the $14 billion contract to Ericsson over five years, that signifies a much deeper relationship with Ericsson than anyone else. “You have to start somewhere,” he said, and for AT&T, they wanted to get the SMO layer done, as that was critical.
Where the most disruption is expected to occur is with the RU, Zeiler said. That’s not easy, and it involves driving an ecosystem of innovative radio developers. AT&T will be leading the RU diversification effort through its supply chain, he said.
It’s worth noting that AT&T plans for 70% of its wireless network traffic to flow across open-capable platforms by late 2026. The company expects to have fully integrated open RAN sites with Ericsson and Fujitsu starting this year. Corning and Intel also were named in AT&T’s public open RAN commitment.
But make no mistake, the relationship with Ericsson is a long one and a lot of thought went into the decision-making process, according to Zeiler.
“Whenever you are announcing a partnership of this magnitude, you have to look all your partners in the eye … and make sure everybody is all in,” he said. “The most critical piece … was making sure that the open commitment is met, and that we all protect ourselves.”
Ericsson: Yes, we are open
From Ericsson’s point of view, “we’re building a truly open network,” said Paul Challoner, VP of Network Product Solutions at Ericsson.
“Every interface is open. We believe, as Ericsson, that we need to compete in the marketplace for the business of AT&T … We need to execute well but we have built the capability for every one of those interfaces to be open.”
Challoner said the definition of “open” is important. “We have a million radios that are hardware ready for those open interfaces already deployed” around the globe, and the software on those radios must meet the open performance standards.
One of Ericsson’s obligations is building an ecosystem of developers to create rApps, which are software applications designed to run on the non-real time RAN Intelligent Controller (RIC).
Over 700 developers are working on rApps outside of Ericsson today, and they’re working on more than 50 different rApps, with 17 ecosystem partners in its program, he said.
What about the DU?
Lopez said a lot of detractors of open RAN point out issues of performance, and some of that is related to Massive MIMO and the DU.
What are they doing to make sure what AT&T deploys is better than current implementations?
“We believe that the DU part is taken care of,” Challoner said.
He was referring to a debate last year about whether the open RAN structure was affecting performance, especially on the uplink. That’s where Ericsson worked with the O-RAN Alliance to get the specification of the open fronthaul sorted out, “to what we believe would be appropriate performance to fix the uplink,” he said.
That’s thanks to the uplink performance improvement (ULPI) project for Massive MIMO radios. That dealt with the DU part and with the latest specification, the RU part, to the point where they believe they have a good performance solution that they can take to mass market, he said.
Until next time, we’ll take a tip from the “U” camp and say: CU later.