What will we do with 6G?

Why talk seriously about 6G? 5G is barely up and running and yet numerous 6G research projects and white papers – from both academia and suppliers – are stirring up industry discussion and calling for R&D action.

One 6G research project is Hexa-X, led by Nokia, and billed as Europe’s “flagship initiative.” Backed by various vendors, communication service providers and research institutes – as well as funding from the European Commission – Hexa-X officially began work on “6G research and pre-standardisation” on 1 January 2021.

Peter Vetter, head of access and devices research at Nokia Bell Labs, makes no apology for paying attention to 6G now even though commercial systems are generally not expected to be ready until 2030 at the earliest.

“You need a defining direction,” he told 6GWorld. “2030 might seem like a long time out but experience shows that it takes ten years or more before a fundamental new technology sees commercial daylight.”

Vetter’s view is you first need to establish what the 6G use cases are likely to be and then work out what is needed from networks and devices to support them. “When you have these use cases it gives you the test of reality,” he added. “Are you truly solving a human need problem, or are you just inventing technology for the sake of it?”

The “Vision Thing”
One popular idea among 6G visionaries is greater interaction between physical, digital and human worlds, helped along by advances in artificial intelligence and machine learning (AI/ML).

To some extent this is already happening with 5G where ‘digital twins’ – digital replicas of the physical world – are used to predict possible machine failures in factories. Predictive maintenance of this sort, aided by AI/ML, is seen as one of the more promising 5G use cases.

As Samsung puts it in a 6G white paper, however, future users of digital twins will be able to explore and monitor physical reality in a virtual world – observing changes or detecting problems – “without temporal or spatial constraints.” When complemented by AI/ML, this can lead to recommendations on “the most optimal actions” – Vetter’s words – to be taken in the physical world.

It doesn’t stop there. Samsung envisages that 6G-enabled users will be able to go beyond observation and actually interact with digital twins using VR devices or holographic displays.

The notion of human ‘immersion’ and interaction with the digital world is a recurring 6G theme. In an early 6G white paper published by research university Virginia Tech (VT) in February 2019, the authors flagged the potential of wireless brain-computer interactions (BCI). Traditional BCI applications, they said, were pretty much limited to healthcare scenarios where humans can control prosthetic limbs or nearby computing devices using brain implants.

In a future 6G environment, VT thinks wireless BCI tech will allow people to interact with their surroundings and other people via a slew of discrete devices – wearables, ‘smart body’ implants, and devices embedded in the world – and allow different and richer types of connectivity.

Advanced communication of this sort will include haptic messages, which simulate touch, and ideas related to affective computing in which a device – through the likes of sensors, microphones, cameras and software logic – has the ability to detect and appropriately respond to the user’s emotions.

Vetter thinks aggregation of multiple devices in the 6G world will amount to an “intuitive human-machine interface” capable of recognising the user’s mood through the likes of facial and gesture recognition, as well as from body sensors monitoring stress levels, and then make appropriate recommendations. If you’re about to have a heart attack, a properly primed 6G platform should know about it.

Yet making all this happen needs trusted AI/ML technologies, and ‘connecting intelligence’ is one of the key 6G research areas identified by Hexa-X.

Another Type of 6G Vision
Michael Peeters, Vice-President of the connectivity domain at imec, an R&D hub for nano and digital technologies based in Belgium, thinks the number one priority for 6G – as with 3G, 4G and 5G – should be to ensure greater capacity for apps ever more hungry for bandwidth. “If we don’t focus on that then we’re not doing the right thing,” he told 6GWorld.

Last November, imec officially launched its Advanced RF programme. The aim is single-link data rates of 100Gbps, microsecond latency and significantly higher energy efficiency of less than one nanojoule per bit. The programme is looking to put semi-conductor performance through its paces at frequencies above 100GHz, initially at 140GHz followed by 300GHz. Those two frequency bands are attractive since large 20GHz chunks of bandwidth are available in each of them.

CMOS, or complementary metal oxide semiconductor, has traditionally been the semiconductor material of choice but that is unlikely to cut it in a more demanding 6G environment. “Once you go beyond 100GHz, the efficiencies and switching speeds of CMOS really start to suffer,” said Peeters. “We believe strongly that you need to shift to a different material system, especially for the power amplifiers.”

As such the Advanced RF programme is turning its attention to indium phosphide, a new material which imec sees as a promising solution in combination with CMOS. According to Peeters, a 140GHz integrated 5G module that is foundry grade and manufacturable at volume should be ready within five years. The basis of a 300GHz version should also be in place by that time.

Hyper-Connected
Walid Saad, associate professor in the Bradley department of electrical and computer engineering at VT – and one of the authors of the February 2019 whitepaper – seemed convinced that this new, hyper-connected world involving humans and machines will emerge by 2030.

Speaking at the inaugural 6GSymposium event hosted by 6GWorld on a panel called “Shaping up 6G: Drivers, use cases and KPI requirements” Saad talked enthusiastically about multi-sensory applications and ‘human control processing’.

“Many of us think of 6G as going more towards machine connectivity, which is true of course, but we also start to see the human coming into play in a different way,” he said. “Before, the human was a smartphone user, a laptop user and watching video. Now the human is embedded with the machine.”

As way of explanation, Saad envisaged that our brains and organs will be “connected directly to the network, either to immerse in a virtual world, interact with a hologram, or control a drone.” The VT professor argued that such will be the proliferation of these new types of devices that 6G will see the end of the smartphone era.

Saad was not a lone voice on the panel when it came to extolling 6G’s virtual virtues. Sunghyun Choi, SVP and head of the advanced communications research centre at Samsung Research in Seoul, said customers will not experience “truly immersive extended reality [XR]” – to his mind a key use case – until 6G arrives. Choi envisaged availability of much more capable XR devices by 2030. “In many cases, the capabilities and the performance of today’s VR/AR devices do not meet customers’ expectations,” he said.

Co-panellist Afif Osseiran, director of industry engagement and research at Ericsson, agreed. “If you want to do extreme AR, or [high fidelity] mobile holograms, data rates provided by 5G are not sufficient,” he said. “It remains to be defined, but you need an [improvement] factor of at least ten, maybe 100.”

That’s All Very Well, but
Ideas surrounding AR, VR and XR – and the related concept of digital twins – have been around for some time. So too has AI/ML. Think back a few years ago and, aside perhaps from brain-computer interfaces, 5G was pitched by many – especially from the telecoms supply side – as being able to deliver on this exciting digital future.

Mazin Gilbert, Vice President of advanced technology at AT&T Labs, ruefully pointed this out at the 6GSymposium event. He seemed to imply that the ‘vision thing’ can was being kicked down the road until 6G comes along. On this reading, the 5G promise of enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC) and massive machine-type communication (mMTC) has not lived up to the expectations – albeit high ones – expressed in the mid-to-late 2010s.

Industry consensus has instead veered towards the view that only ‘extreme’ 6G versions of eMBB, URLLC and mMTC, combined with AI/ML, can provide the illusion of infinite capacity, precision localisation and virtual reality multisensory experiences.

Given that tech visions can become blurred (or postponed) as time passes, Karri Kuoppamaki, Vice President of technology development and strategy at T-Mobile USA, sounded a note of caution. “It’s OK to get excited about 6G, but we have to get excited the right way,” he said. “We should avoid unnecessary hype and not fall victim to the shiny object syndrome.”

Not surprisingly for an operator investing heavily in 5G, Kuoppamaki does not want industry to get unnecessarily distracted. “We shouldn’t rush into developing a new technology at the risk of 5G, which is a super-viable and impressive technology for what it was developed for,” he said.

Kuoppamaki’s advice is that industry should keep an eye on how the 5G ecosystem and use cases develop, and take that as a guide to 6G R&D. He argued that a patient and evolutionary approach towards 6G would reduce the risk of making sub-optimal technology choices. “I think there’s a very real chance that 5G technology, as we understand it today, will happily coexist with 6G,” he said. “And maybe, to a certain extent, even merged together in the future to serve use cases that they’re best catered for.”

For all the speculation about 6G use cases, especially viewed from the distant perspective of early 2021, there is always a nagging possibility that industry is falling into the trap again of over promising, despite cautious voices like Kuoppamaki’s.

Saad prefers to look on the bright side: “I’d like to think that when we say 6G use cases, the most important is one we cannot foresee now.” 6G World