T-Mobile’s Neville Ray explains why it’s hard to virtualize the RAN

T-Mobile CTO Neville Ray at MWC (Mike Dano/FierceWireless)
Ray says the radio access network has become increasingly complex in the recent past. (FierceWireless)

BARCELONA—T-Mobile CTO Neville Ray, speaking from his perspective as the board chair for 5G Americas, said the radio access network (RAN) has become increasingly complex over the last several years, and that is why it is particularly difficult to disaggregate hardware from software in the RAN to achieve network virtualization.

“The radio world was complex, and now when you think about new radio technologies like massive beamforming and millimeter wave (mmWave), there’s massive intelligence in the radio environment,” said Ray. “It drives challenges into that disaggregation.” He added that the brain of the radio network is the baseband unit, and that’s become more complex, driving even more difficulty in virtualization. He acknowledged that it might have been easier to disaggregate the RAN when it was simpler, but then, on the other hand, that might have stymied some of the advances in radio technology.

Some open source groups are working on RAN virtualization, including O-RAN. “They’re trying to disaggregate the physical radio from the baseband, which is the brain that drives the radio activity,” said Ray. In fact, 5G Americas just recently published a white paper entitled “The Status of Open Source for 5G,” which delves into some of the work of O-RAN.

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Basically, the goal of disaggregating RAN hardware from software is the same goal as virtualization in the core network. Operators won’t have to buy proprietary vendor equipment from companies such as Ericsson and Huawei. They will be able to buy more generic equipment and then run open source software on it.

Most major operators are already well down the path of virtualizing their core network. For instance, AT&T is on the final leg of having 75% of its core network virtualized by 2020. AT&T first outlined its virtualization project back in 2013 as part of its Domain 2.0 initiative. The plan includes using the open source ONAP software to virtualize and put into production critical network functions. AT&T finished up last year with 65.5% of its network virtualized, which hit last year's goal. So it just needs to complete the final 9.5% this year.

RELATED: AT&T on the homestretch of virtualization goal

While AT&T is a good example of a carrier virtualizing its core, most carriers, including AT&T, are just now beginning to work on virtualizing the RAN. But a newcomer, Rakuten, is surging to the head of the pack in this regard.

Rakuten is building a greenfield mobile network in Japan, using a slew of familiar vendors including Cisco, Nokia, Intel and Quanta Cloud Technology (QCT). Rakuten chose Altiostar Networks for its RAN. And in fact, Rakuten recently announced a strategic investment in U.S.-based Altiostar, which will be completed subject to approval by the Committee on Foreign Investment in the United States. Altiostar’s baseband solution, located in a strategic number of points of presence or aggregation data centers, serves clusters of cell sites. And Altiostar has partnered with commercial off-the-shelf server manufacturers such as QCT to optimize data center type, fully virtualized baseband solutions.

Tareq Amin, CTO of Rakuten, said at a press event today at MWC 2019, “I think this radio access has been the daunting challenge in this industry for some time, and I’m really glad we’re finally making some progress.”

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