A common core for fiber, 5G could be just around the corner

Convergence between wireline and wireless networks is one of those ideas that feels like it’s perpetually on the horizon. But experts told Fierce a perfect storm of industry trends – virtualization, disaggregation, 5G, fiber, cloudification – has finally come together to bring the long-sought after approach within reach.

Dave Allan, distinguished engineer at Ericsson and leader of the Broadband Forum’s Wireless-Wireline Convergence (WWC) Work Area, told Fierce he’s been working on convergence for a long time. The ultimate goal, of course, is a common core for both the fixed and mobile access networks. But when the industry took a previous crack at convergence about 10 years ago, he said the necessary puzzle pieces just weren’t in place.

“The thing was, back then cell phones were basically things like flip phones and BlackBerries and the smartphone was only just starting to emerge. And what’s more we weren’t really talking about cloud computing a lot either,” he said. The big difference now is that everything but the core – the devices, the protocols – is IP-based. Additionally, 5G fixed wireless access is already doing the legwork to commoditize 5G-enabled residential gateways (5GRGs), Allan said.

“There’s a lot of motivation for this to happen and a lot of the enablers are already in place,” he said. Allan noted that everything but the core and subscriber management is essentially already converged. That, taken with trends in cloud computing that allow convergence to happen via a software upgrade, means “voila, you have the ability to collapse so much duplication in a carrier network.”

Indeed, operators are keen to press ahead with efforts to streamline their wireless and wireline networks to cut down on duplication and reap opex savings. Vodafone, which recently trialed a disaggregated broadband network gateway (BNG) with Nokia and Cisco, told Fierce it sees that functionality “evolving to include interoperability with [a] converged 5G core.”

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The Broadband Forum has been working shoulder to shoulder with wireless standards body 3GPP on convergence specifications since early 2017, when the groups held a joint meeting to look at use cases, set goals and establish how work should proceed. They’ve been actively writing specifications to make convergence a reality since 2019, with 3GPP addressing this in its Release 16 standard.

Broadband Forum finished its Phase 1 specifications addressing fundamentals of convergence, including how to support a 5GRG on a wireline network and how to begin transforming the network, last year. Allan said it is currently in the midst of work on Phase 2, which will tackle expanded deployment options, added functionality, new revenue sources and other improvements.

While vendors and operators are heavily focused on 5G, Allan said several “major operators” and a handful of vendors are already doing proof-of-concept tests of technology based on the Phase 1 specifications.

Ken Ko, managing director of Broadband Forum, noted there are several different routes to convergence but at least one of the defined paths would eliminate the traditional BNG entirely and terminate residential service “in the [5G] mobile core itself after going through an adaptation function in the access network.”

He added “in the most forward-looking version of that convergence, there’s not even much of an adaptation function. The mobile protocols are actually coming all the way out to and through the 5GRG.”

Allan summed up why convergence is such a big deal and why operators continue to chase it.

He explained once an operator’s core network becomes a common digital platform “the services are common, the tooling is common, [and] you can provide ubiquitous policy irrespective of access to a given subscriber for things like parental controls, corporate access et cetera. That’s kind of huge.”