Nokia is coming up with a full suite of open-RAN-defined interfaces that will work with its existing AirScale radio access network (RAN) portfolio.

Nokia says that by taking the approach of building the open interfaces on top of its existing solutions, service providers can choose to pursue an open RAN path, or not. An initial set of open RAN functionalities will become available this year, while the full suite of open-RAN-defined interfaces is expected to be available in 2021.

Open RAN means that the radio unit (RU) is separated from the distributed unit (DU) and the centralized unit (CU). In 5G, the DU and CU can be virtualized and run on commodity servers. And then an operator can buy RU hardware from a number of companies, introducing more competition in the radio ecosystem.

Of the three main global RAN vendors — Nokia, Ericsson and Huawei — Nokia is the only one to actively commit to open RAN. Joe Madden, principal analyst at Mobile Experts, said Ericsson has not made a similar announcement along these lines to say that it would actively support products with open RAN availability or sell radios separate from the distributed unit.

Meanwhile, several operators have now committed to open RAN. One of the most notable is Japan’s Rakuten Mobile.

Nokia is Rakuten’s primary vendor for remote radio head hardware at its macro sites. The Finnish vendor agreed to open up its CPRI interface in order to work with Rakuten. Rakuten Mobile’s CTO Tareq Amin said this was a big concession for Nokia, which he really appreciates, because in the past, vendors kept their CPRI interfaces proprietary so that operators would not have the choice of mixing and matching hardware and software.

RELATED: Rakuten explains vendor roles in greenfield network

Madden said Rakuten was going to do open RAN with or without Nokia. But Nokia stepped up to the plate and helped Rakuten deploy a first-of-its-kind network even though it didn’t get all of Rakuten’s RAN business. “Altiostar and other vendors don’t have millions of base stations deployed in the field,” said Madden, adding that Nokia’s experience was really helpful for the greenfield project.

Nokia may also be reading the tea leaves in terms of the trend toward more openness in 5G networks – as well as the U.S. government’s push for open RAN.

In its statement today, Nokia said its “accelerated investment in and firm commitment to O-RAN provides CSPs as well as regulators and political decision-makers with greater assurance that they can embrace openness to secure their telecom supply chain, without concerns about the competitiveness and/or security of their 5G infrastructure."

Nokia also recently announced the next generation of its AirScale Cloud RAN portfolio.

RELATED: Nokia unveils 5G cloud RAN, giving O-RAN a push

The vendor’s solutions use the same software trunk across RAN, Cloud RAN and open RAN.

Madden said open RAN “is starting to catch fire.” Not only are new mobile operators such as Rakuten and Dish working with open RAN, but he thinks Verizon and AT&T will start to get on board with groups such as the Open RAN Policy Coalition.

He said legacy vendors will probably dip their toes in the open RAN waters by requiring that new equipment they buy must comply with open RAN standards and interfaces. Over the long term, that will give them the flexibility to buy radios from different vendors.