SK Telecom has drawn attention to some of the challenges it would face in building a 5G network based on 28GHz spectrum and says it is now looking at the use of sub-6GHz frequencies to support the next-generation mobile technology.
The South Korean operator last year carried out field trials of 5G technology based on 28GHz spectrum, which has been the focus of early 5G activities in several advanced markets, including South Korea, Japan and the US.
While the 28GHz band is not available to operators in other parts of the world, the amount of spectrum available in this range -- as well as other high-frequency bands -- should allow operators to provide much higher-speed services than over lower frequencies.
But these airwaves also come with major drawbacks. For one thing, operators would need a lot more site equipment to support a 28GHz deployment, simply because signals do not travel as far in this band as in lower frequency ranges.
Changsoon Choi, a senior manager with SK Telecom's corporate R&D center, says that power consumption on devices is a concern when it comes to 28GHz spectrum, and that it may be hard to install chips without blocking the wireless signal.
"With 28GHz, it is going to be challenging to integrate the chipsets into the smartphone devices," he told Light Reading at last week's Mobile World Congress in Barcelona.
In the meantime, the operator's interest in using much lower, sub-6GHz spectrum to support 5G services appears to be growing.
"We are looking at the possibility of getting spectrum below 6GHz [for 5G] and the government is considering this," says Choi. "No decision has been made but it is likely that we will be able to get this at the stage of commercialization."
The use of sub-6GHz spectrum is likely to reduce the capital expenditure bill dramatically and would align SK Telecom (Nasdaq: SKM) with a number of European operators that are similarly interested in using "mid-band" airwaves to provide 5G services. (See Vodafone CTO 'Worried' About 5G mmWave Hype.)
According to a report from Barclays cited by German telco Deutsche Telekom AG (NYSE: DT), the cost of deploying a nationwide 28GHz-based 5G network in the US could run to as much as $300 billion. (See DT Plots 5G Across Entire Footprint.)
While mid-band airwaves are bound to have a big role to play outside urban hotspots, Choi says that sub-6GHz spectrum could also be used with 5G in more densely populated areas.
Assuming progress on 5G standardization goes according to plan, SK Telecom now hopes it may be able to launch a commercial 5G service as soon as 2019.
But a widespread rollout of 5G technology will be challenging given the operator's spending constraints.
In February, SK Telecom said it had no plans to increase capital expenditure this year from the level of 2 trillion Korean won ($1.7 billion) it spent in 2016, even though it expects sales to rise 4% in 2017. (See Can SK Telecom Write a New Telco Growth Story?.)
Choi says that senior managers are pushing for a reduction in both capital and operating expenditure even as the operator launches 5G services.
"One of the things we are doing is to make the infrastructure more virtualized and open so that there is more competition and less expense," he says. "There are some core network and virtualized RAN [radio access network] parts where we can have more companies [involved]."
A desire to reduce the bill for 5G rollout appears to be one of the key reasons behind SK Telecom's decision last year to join the Telecom Infra Project (TIP), an initiative led by Facebook whose goals include reducing infrastructure costs through technology innovation.
Deutsche Telekom, which is also a member of TIP, is similarly hopeful that using more advanced software in conjunction with "standardized" hardware could make the rollout of a 5G radio access network far more economical. (See DT CTO: Costs Must Fall or 5G 'Won't Work'.)
Choi agrees with the German operator that such technology developments are likely to put a lot of pressure on traditional vendors expecting a sales boost from the rollout of 5G.
— Iain Morris, , News Editor, Light Reading