COPENHAGEN – Digital Transformation World – Terje Jensen smiled ruefully when asked about his company's involvement in open RAN.

"We are very pro everything that is open," began Telenor's head of network architecture before dashing any hopes the open RAN vendor community might have had.

Across its eight markets, the Norwegian telecom incumbent has already installed 5G-enabled basestations at more than half of its 103,000 mobile sites, he told Light Reading. And that does not leave much room for the fledgling technology.

"The window for open RAN is getting smaller and smaller," said Jensen at this week's Digital Transformation World show in Copenhagen.

Telenor is even now in discussions about 5G contracts for its remaining sites, he revealed, and these are evidently not happening with open RAN vendors. All this means Telenor is likelier to use the technology in private networks than at its main outdoor sites.

"The consequence is that it will potentially be a much smaller market," said Jensen.

The remarks by the Telenor executive point to one of the biggest problems for open RAN – its relatively late arrival on the 5G scene. The idea is to boost interoperability so that operators can mix products from different suppliers at the same mobile site and not stick monogamously to one vendor's system, as they mainly do today.

But having already deployed a lot of traditional 5G gear, Telenor and others would have to rip out and replace equipment that has not fully depreciated to introduce open RAN.

Unfortunately, for open RAN, the benefits of the technology seem to be insufficiently compelling for that kind of expensive overhaul. Strictly speaking, it is just a set of interfaces linking different parts of the radio access network. These would, for instance, allow one vendor's baseband software to communicate with another supplier's radios.

Telco proponents hope it will boost competition in a market that has been dominated by Ericsson, Huawei and Nokia. Ultimately, it could drive down prices.

Fatal attraction?

There are few other obvious attractions, however, and increasing the number of suppliers to a network could even be more expensive, according to Neil McRae, the chief architect of the UK's BT.

The virtualization of the RAN that is likely to accompany most open RAN deployments could also deliver cost savings and service-related benefits, but Telenor does not sound altogether persuaded.

"That depends a bit on the fiber situation," said Jensen.

"What is the benefit of putting that in the cloud and does it need special hardware or accelerators? So far it seems to be yes, it does need some dedication. Opex savings from simpler sites could be one of the main factors – less equipment, less energy, less visits."

In the set-up he describes, an operator would be able to run its baseband software on general-purpose equipment. It could then strip this away from mobile sites and move it into a smaller number of data facilities, reducing the amount of equipment used, slashing energy consumption and simplifying maintenance.

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The risk is that technology drawbacks offset those efficiency gains. As Jensen notes, fiber links would be needed to carry signals between the data facilities hosting baseband gear and the radio sites.

Nor can general-purpose equipment match the performance of the customized silicon found in a traditional RAN, although several chipmakers have now developed the accelerators to which Jensen refers. Used alongside x86 processors to handle baseband (or Layer 1) functions, these could help to overcome the performance-related problems.

Whether they measure up against the chips developed by the big kit vendors is questionable, though.

"Our Layer 1 chip beats on performance and cost and power consumption any merchant silicon or any general-purpose processor," said Tommi Uitto, the head of Nokia's mobile business, during an interview with Light Reading in June.

Nokia's opponents, naturally, say the Finnish vendor has a vested interest in knocking open RAN, which could leave it with a smaller share of the market in future. And for all the doubts, Telenor is now looking into RAN virtualization, Jensen tells Light Reading.

"It is not like we are sitting still," he said.

"We are planning field trials early next year." Fans of network disaggregation will be watching closely.

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— Iain Morris, International Editor, Light Reading