5G is Just Getting Started; Time for 6G

OULU, Finland — When officials in this innovation hub invited journalists to have a look at the work under way to initiate research on 6G wireless networks, I immediately thought, But we don’t even have commercial 5G yet. How can we be talking about 6G? I’ve spoken to others who have confessed the same reaction.

Once you get there, you realize that for now, “6G” is just a marker. Most of the work going on in Oulu, as in the rest of the world, targets the 5G rollout: conducting trials, defining use cases, and figuring out business models. It’s still early days. But Nokia is already shipping millions of its AirScale radio access platform for 5G installations in cities around the world, Erja Sankari, vice president of supply chain engineering, told EE Times in an interview.

The University of Oulu has attracted more than €250 million in
funding for its flagship 6Genesis project. (Image: EE Times)

As the 5G rollout gets under way, there needs to be a vision for what’s next for mobile networks far beyond what is possible today. Will that next big thing be “5G Long-Term Evolution [LTE], or is it 6G?” said Ari Pouttu, professor for dependable wireless at the University of Oulu’s Center for Wireless Communications. Looking to kick-start funding for their work on 5G’s successor, university researchers opted for the moniker 6G to suggest the scope of the envisioned leap in capabilities and required rethinking of technologies and materials.

The university has since attracted more than €250 million in funding over the next eight years for its flagship 6Genesis project.

The 6G initiative is a vision for 2030. Over the next eight years, the 6Genesis program will consider the impact of a data-driven society enabled by nearly instantaneous, unlimited wireless connectivity.

6Genesis, or the 6G-Enabled Wireless Smart Society & Ecosystem, is focused on the implementation of 5G communications technology and the possible development of a 6G standard. It will help industry commercialize 5G by carrying out large pilots with a test network. At the same time, it will explore development of the essential technology components that would be needed for 6G, targeting wireless connectivity and distributed intelligent computing. The long-term research will focus not just on communications between people but also on communication between devices, processes, and objects. The University of Oulu is leading the project, collaborating with researchers from Nokia, the VTT Technical Research Center of Finland, Aalto University in Finland, BusinessOulu, and the Oulu University of Applied Sciences.

NEARLY INSTANTANEOUS CONNECTIVITY

How far into the future does this out-of-the-box thinking look? The 6G initiative is a vision for 2030.

Over the next eight years, the program will consider the impact of a data-driven society enabled by nearly instantaneous, unlimited wireless connectivity, Pouttu said. Researchers will explore the devices, circuits, and distributed-computing requirements that could satisfy expectations for artificial intelligence (AI)-inspired applications serving every aspect of society with ubiquitous wireless conectivity.

“Humans are already connected, so the promise of 5G or 6G will be to connect even more objects,” said Pouttu. “Near-instant connectivity is still not fully solved in 5G in terms of latency. Millisecond latency is not good enough for some [time-critical] applications, so there is still a lot of potential to improve communications capability.”

Handling the massive data volumes envisioned will require terabit/second communications, he said. And as data rates rise, so will frequency requirements — from 100-GHz all the way up to terahertz frequencies.

There is already a line of thinking that there will be 1,000 radios per person in the next 10 years, said Pouttu. “[Communications] distances will be short, with radios everywhere. We’ll need to start looking at totally new ways of providing over-the-air communications. Could this mean the renaissance of ultra-wideband radio, or will it be OFDM [orthogonal frequency-division multiplexing]?”

Everything from device and circuit technologies to materials science may require a rethink, said Pouttu.

One research focus will be the mobile edge intelligence required for more data-driven, nearly instantaneous connectivity. Distributed computing, particularly multi-access mobile edge computing, will become even more important. “A lot of computing will be done at the edge, with a lot of modeling done in the handheld device itself,” said Pouttu. Apple’s September 2018 launch of three iPhones powered by the 7-nm A-12 Bionic system-on-chip, enabling up to 512 GBytes of memory, shows that the trend is already unfolding.

Aarno Parssinen, professor of radio engineering at the University of Oulu, said researchers need to take the long view because technology can take decades to mature. “Our timeline of development is not in quarters,” he said. “For us, 10 years is really a short time frame.

“If you look at millimeter wave, the first fundamentals might have been done around the 2000 time frame, but industry has really only developed a level of maturity with this 10 to 15 years later,” said Parssinen. “Even so, 5G millimeter wave is still 10 times more difficult to implement. The same fundamental principles might apply, but the dimensions are getting smaller. The antennas are getting tiny, with more electronics around [them], and this will get even more difficult in terahertz communications.” Today’s transistors can’t cope with terahertz frequencies, he said.

The proposed terahertz frequencies will contain an absurd amount of data, increasing data intensity not only in information technology terms but also for wireless transport. “We must come up with a solution that makes this reasonable and physically possible in those frequencies,” said Parssinen. “We need to do things that cannot really be done yet. But that is the purpose of science.

“The goal is to make new things in frequencies that have enabled significant advances in radio astronomy and other scientific or otherwise very demanding applications. The focus is on harnessing this for commercial use in reasonably priced, small devices, and [the challenge is] how to get the radio signal to travel in this environment.”

5G TEST NETWORK

The more immediate challenge is the 5G rollout. Toward that end, the 6Genesis project includes a 5G test network (5GTN) based on Nokia’s core network products and operated by the University of Oulu and VTT, with funding support from roughly 25 partners.

The Oulo 5G test network partners range from technology to
health and public service organizations. (Image: 5GTN Project)
The 5G test network in Oulu. (Image: 5GTN Project)

The 5GTN acts as a verification platform for theoretical 5G research and is a testbed for R&D and trials by the partners, which range from technology companies to health and public service organizations. The test network is centrally located at the university, and the partnering businesses connect to it using SIM cards. Product developers can test their technology prototypes, with access to all functions and interfaces on the network, and other businesses can run trials of potential services that would benefit from 5G connectivity.

The network architecture uses 3rd Generation Partnership Project (3GPP)-specified evolved packet core elements and LTE radio access technology, with an emphasis on small-cell–based solutions. The 5GTN project team can also grant frequency licenses. Active projects include care, wellbeing, and fitness; e-health at home; media production and distribution; and a Nokia automated factory that uses 5G technology.

‘BETTER WAYS TO DO THINGS’

Given the work that remains to be done on 5G, it’s easy to dismiss the 6G discussion as premature. “I think 6G is a red herring until it is really defined and not worth much effort before 2020 to 2022,” said Mike Short, who spent 17 years at Telefonica and is now chief scientific adviser with the British government’s international trade body. “We need to see real 5G customer demand and rollout first.”

The LTE network on campus at the University of Oulu, operating
in Band 7 at 2.6 GHZ, feeds into the 5G test network.
(Image: EE Times)
5GTN partners use a SIM card to access the University of
Oulu’s 5G test network. (Image: EE Times)

But scientists and researchers are already thinking about the challenges of next-generation networks, and work is under way to address them. According to some reports, China began researching 6G at the end of 2017. The International Telecommunication Union, looking toward 2030, established a focus group last year to investigate backbone technologies for next-generation networks. And Semiconductor Research Corp.’s Center for Converged Terahertz Communications and Sensing is looking at developing technologies for future cellular infrastructure using hubs with massive spatial multiplexing. The approach would provide 1 to 100 Gbits/second to the end user, with 100 to 1,000 simultaneous, independently modulated beams and with aggregate hub capacities in the tens of terabits/s.

Finding “even better ways to do things” is just a manifestation of human curiosity, said Oulu professor Pouttu. “Don’t worry about applications or business. There are other guys to do that. “We are engineers. We are curious.” ■