Japanese telecom giant NTT DoCoMo is deploying Nokia’s open radio access network (RAN) components in its nationwide 5G network, which adds a big-name vendor to the carrier’s open RAN efforts and bolsters Nokia’s efforts to better penetrate the open RAN market.

NTT DoCoMo is integrating Nokia’s 5G AirScale baseband products, including the vendor’s centralized unit (CU) and distributed unit (DU) software. This will allow the operator to connect open radio units (RUs) from other suppliers into its nationwide 5G network.

The NTT DoCoMo news comes just a week after Nokia said it successfully completed open RAN interoperability testing with Mavenir. That work showed interoperability between a Mavenir base station and Nokia’s AirScale Baseband using an O-RAN Alliance compliant fronthaul interface.

This work for Nokia moves the vendor somewhat closer to open RAN . The vendor has been on the outside looking in as part of the broader open RAN vendor ranking, with CEO Pekka Lundmark recently stating that the market was still working through those integration challenges.

“We are ready to deliver all alternatives that customers want. This is not a religious question for us at all,” Lundmark said during the Goldman Sachs Communacopia + Technology Conference in September, though he did point to challenges of CU and DU integration onto compute platforms and the accompanying increase in power consumption. “But these are some of the technical realities that O-RAN and cloud RAN are facing at the moment.”

However, partners have noted a definitive change in that focus. Dennis Hoffman, SVP and GM for Dell Technologies’ Telecom Systems business, said this week in an interview with SDxCentral  that Nokia was particularly “embracing open forms of RAN.”

Despite the similarities, NTT DoCoMo’s Nokia integration is not part of the carrier’s recently launched OREX initiative. That program, which was announced at the recent MWC Las Vegas event, is designed to provide customizable options of precertified open RAN components. These are packaged for RAN, and NFV management and network orchestration (MANO) services.

OREX launched with 13 vendor partners, including AMD, Dell Technologies, Fujitsu, Hewlett Packard Enterprise (HPE), Intel, Mavenir, NEC, NTT Data, Nvidia, Qualcomm, Red Hat, VMware and Wind River. However, notably missing were large-scale RAN providers like Ericsson, Nokia, Samsung and Huawei.

“They have their own RAN, they have their own RUs and they have their own interfaces so we can’t choose that,” Sadayuki Abeta, global head of open RAN solutions at NTT DoCoMo, told SDxCentral.

This vendor dynamic remains one of the larger hurdles toward broader open RAN deployments. While NTT DoCoMo does have a solid lineup of OREX partners, they lack the scale of the market’s larger players.

Abeta said this has resulted in pricing challenges for those smaller vendors. “If they can provide 10,000 to 100,000 [units] then they can provide it very cheaply, but that is a challenge for open RAN in commercial [networks], it’s an issue of [total cost of ownership],” Abeta said.

A Nokia spokesperson noted that the latest NTT DoCoMo integration was not tied the vendor to NTT’s OREX project, “at least yet.”

This integration is a growing focus for network operators that want to use open RAN as a way to increase their vendor base. However, many are finding persistent interoperability challenges.

“Management of the overall structure was an area that we struggled with,” David Zufall, VP wireless infrastructure development at Dish Network, explained during a panel discussion at the recent National Telecommunications and Information Administration (NTIA) 5G Challenge event. “How can we make sure that the entire software distribution system is clean, that we’ve got the ability to manage all the individual vendors.”

Zufall said operators and standards bodies will need to keep pressure on vendors in order to gain greater interoperability across the open RAN ecosystem.

“I think that’s going to be up to [operators] to force it among our vendors,” Zufall said. “We can define the basic layers, that it’s going to be a cloud-native environment and we have our principles, so I think we can define the environment. But I think we have to take the bold step and say, ‘I am going to have a multi-vendor network and I am going to have a multi-cloud network and I’m not just going to use somebody’s middleware to enable the interoperability that happens to work on both of them. We were willing to do it on the RAN and we saved some money. We’re willing to do it on hardware, but we have to go to the next step, and I think that’s on the operator community to kind of force it across our vendors.”

That “middleware” step has been highlighted by the growing push by vendors like Red Hat and its OpenShift platform and VMware with its Telco Cloud Platform in tying together those hardware and software layers using a easier to control interface. These have been used by many vendors and cloud providers to offload those final interconnectivity efforts, which Zufall said has hindered true interoperability efforts.

“Everybody mentions Ericsson and Nokia, to use the big names: They have the same problems internally with their boxes that don’t all talk nicely together, so it’s not like it’s solved if you just don’t go to [open RAN],” Zufall said. “We have to look at it and say this is a problem. If we are going to make better networks we need to fix it and not look to take a step backwards and say this is not a reason for not moving toward an [open RAN] environment.”