Three UK is anticipating a coverage boost when it shifts from the non-standalone to the standalone version of 5G technology and is already "well placed" to make that jump, an executive from the operator has told Light Reading.

The company is preparing to switch on a non-standalone 5G service, which piggybacks on its existing 4G "core" -- the brain of the network that makes decisions about traffic routing and stores important IT systems.

With standalone 5G, Three would introduce new core network systems to go alongside the 5G radio. The operator is not disclosing details of the timeframe for that shift but reckons standalone would deliver a power boost for the 5G network by cutting out the need to run 4G and 5G radios concurrently.

"You can just have 5G and so all the power goes into 5G and there is a big coverage improvement," says Mike Eales, Three's head of network services strategy and architecture. "The uplink to the device only has one radio running and that expands the overall coverage."

Another standalone 5G benefit, he says, is the ability to do network slicing in the radio access network as well as the core. "At the moment, with non-standalone, you can only do slicing with the core," he explains. "Standalone opens up more options and different business models because you can slice end-to-end and offer guaranteed service in the RAN as well as the core."

Network slicing is a long-heralded 5G feature that would allow an operator to effectively reserve a part of the 5G network for a specific service or customer, such as an automated factory. Its usefulness has recently been called into question by regulatory plans in several countries to license spectrum outside the telecom sector, allowing other companies to build their own local 5G networks.

When it comes to the standalone shift, Three believes it is in a stronger position than some other service providers because it has already made investments in up-to-date core network technology developed by Finland's Nokia. It is also working with Affirmed Networks and Mavenir -- two smaller software specialists -- on its core network.

"We are using Nokia for the cloud core, the infrastructure and some of the applications, but Affirmed and Mavenir are also providing applications that are already running on the Nokia core," says Eales. "We are already in a multivendor environment and it is likely we'll reuse those vendors going into a 5G core as well."

Asked about the difficulty of making that transition, Eales says it would entail a major re-engineering. "The architecture is shifting to IT-style architecture and that is a big shift," he says.

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Under its Release 15 update, the 3GPP, the main standards group involved in 5G development, finalized initial specifications for standalone technology last year. Further improvements and modifications are expected with Release 16, due in March next year.

But Three hopes to make final vendor selections "very quickly," says Eales, and is currently in talks with its existing core network vendors and other companies about investment plans.

Discussions are unlikely to include Huawei, the Chinese vendor that some officials regard as a threat to national security because of its perceived links to the Chinese government. The UK is carrying out a supply chain review to determine if Huawei will be allowed to sell 5G products. Three's assumption is that authorities may decide to ban Huawei from providing core network products but allow it to continue selling radio equipment.

Accordingly, it has picked Huawei as its sole 5G radio supplier and is also replacing Samsung in its 4G network with the Chinese vendor to guarantee interoperability between the two radio technologies.

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— Iain Morris, International Editor, Light Reading