MWC: AT&T, Ericsson hit first open RAN milestone with a 5G cloud RAN call

  • The transformation of AT&T’s RAN will see “hundreds of milestones,” and this announcement is just the first

  • AT&T now has commercial traffic flowing on Cloud RAN sites located south of Dallas, Texas

  • Ericsson waited to adopt open RAN because earlier it felt there were some aspects that simply weren’t good enough

MOBILE WORLD CONGRESS, BARCELONA — Every company wants to make some kind of media splash at MWC in Barcelona. And AT&T and Ericsson are certainly making a splash this week, following their open radio access network (RAN) partnership, which they announced in late 2023. This week, they announced the deployment of Ericsson’s cloud RAN technology in some sites in Texas, which they used to make a call.

AT&T now has commercial traffic flowing on Cloud RAN sites, the first ones of which are located south of Dallas, Texas. As part of the live deployment, AT&T and Ericsson have migrated one frequency band 3700MHz for their C-band traffic to cloud RAN infrastructure.

Chris Sambar, head of Network with AT&T, said, “By moving traffic to cloud RAN sites, we’re accelerating our C-band deployment and continuing to virtualize our network.”

Fierce Wireless spoke with Yossi Cohen, president and CEO of Ericsson North America, and he said the transformation of AT&T’s radio access network (RAN) will see “hundreds of milestones,” and this announcement is just the first.

“Usually, network expansions are incremental,” said Cohen. “This different approach by AT&T — this is not an incremental change. It’s changing the architecture and how it will be managed.”

He said traditionally, Ericsson would provide its baseband with its own silicon. But now, AT&T is using general purpose servers from Dell with x86 Intel silicon, and Ericsson will supply the open RAN software that runs on top.

Cohen said, “Up until now Ericsson has only run compute on Ericsson hardware. When we move to cloud we will be able to run the software similar to what runs on Ericsson proprietary but on the x86 servers. Then operators can choose cloud RAN on x86 or purpose-built hardware.”

AT&T has decided to deploy open RAN in 70% of its network. But the operator will still use proprietary hardware in 30% of its RAN.

Dispute in O-RAN Alliance

Last year there was some dispute in the O-RAN Alliance about an uplink modification to open fronthaul for Massive MIMO radios. Some members of the Alliance, including Ericsson, wanted the equalizer function placed in the radio. While other members of the Alliance, including Mavenir, wanted the equalizer function placed as software in the compute.

Ericsson says the dispute has been resolved because the O-RAN Alliance agreed to support both choices. 

“When you do standards, vendors always come up with proposals,” said Cohen. “Eventually there is an agreement, and not everybody is happy.”

Cohen said one of the reasons Ericsson waited to adopt open RAN was that earlier it felt there were some aspects of open RAN that simply weren’t good enough.

“Globally, we have to compete against Huawei’s proprietary interfaces," he said. "We would be losing globally. We have to build radios that are super efficient and giving the highest capacity out of that spectrum. We felt open RAN was holding us back.”

But with the O-RAN Alliance’s agreement to support the equalizer inside either the radio or in the RAN compute has satisfied a concern of Ericsson’s.

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