Are you ready for 6G? Not so fast — it’s going to take a while. The Federal Communications Commission (FCC) on Friday unanimously approved an order to create a new category of experimental licenses between 95 GHz and 3 THz to give researchers and engineers more flexibility to test the capabilities for wireless communications. The commission also made 21.2 megahertz of spectrum available for unlicensed use in several band segments in the lower end of that range.
“I fully expect that within a decade mobile communications systems and cellphones will be operating above 95 GHz,” said Ted Rappaport, NYU Wireless founding director, in an interview with SDxCentral. Rappaport heads up the academic research center and played a key role in demonstrating the potential of millimeter radio wave spectrum, which is now being deployed across the country for 5G.
As the industry grapples with the unfulfilled potential of 5G and waits for more distinct use cases to be discovered, the very notion of 6G is almost unfathomable. “Nobody really knows what 6G is yet,” said Dan Hays, principal at PwC’s Strategy& division. The FCC’s decision is “more of a license to experiment than an indication of future commercial uses.”
While much remains unknown and unproven with respect to 6G and terahertz spectrum, the FCC has a responsibility to allow others to dream of the possibilities, and that approach has already proven worthwhile with respect to millimeter wave, FCC Chairman Ajit Pai said during the hearing. “Extremely high-frequency, short-wavelength bands of spectrum were previously thought to be unapproachable,” he said.
Some of the possible use cases envisioned by Rappaport and his colleagues at NYU Wireless fall into the realms of wireless cognition, sensing, imaging, communication, and positioning. Applications such as robotic and drone fleet control, air-quality detection, health monitoring, see-in-the-dark imaging, high-definition radar, security body scanning, wireless fiber for backhaul, and centimeter-level positioning are all possible, according to Rappaport.
Software’s Critical Role
It’s far too early to draw conclusions about how 6G networks will operate, but where 6G is expected to diverge from 5G is of particular interest. Regardless of the spectrum used for future 6G networks, software is expected to play a critical and increasingly important role. “I think if we assume that 6G is really a continuation of the move towards ever-higher bandwidth and lower latency — that’s a big assumption but if we assume that — then clearly software continues to be central to making it work because something is going to be needed to process, route, and handle all of that increased bandwidth,” Hays said.
Rappaport, who presented some of NYU Wireless’ findings at the FCC hearing, agrees about the importance of software. “Real-time processing continues to need software, and software agility is vital for implementing all the different standards and specific operating points of future wireless modems,” he said.
“Software and machine learning go hand in hand. As we develop more powerful machine learning capabilities, the data that’s being sent from the phone will be cast over wireless channels to the infrastructure, and software at the edge of the infrastructure will be able to learn on the fly what’s happening, what we are seeing as humans, through our phone,” Rappaport said.
‘Extension of Our Brain’
“Our phones will become basically an extension of our brain, of our mind, and it will become a sensory surrogate for what we’re seeing,” he added. “Passing that back to the network is going to require remarkable software capabilities and learning capabilities that allow the phones of the future operating at these very high bandwidths to source, sense, and integrate at the edge of the network what we experience as humans.”
While terahertz spectrum has shown great potential and could eventually become the domain of commercial 6G networks, it will have to overcome some particularly challenging limitations, according to Hays. “It’s greatest potential, at least on land, is limited to extremely short distances,” he said. Short, in this case, is a handful of feet.
“What’s clear is that nothing that any of us do is going to fundamentally change the laws of physics, and it may well be that this spectrum winds up not particularly useful for terrestrial communication, but it could continue to be useful as it has already for scientific purposes,” Hays added.
Software could minimize some of the challenges with propagation, but it’s unlikely to render them moot. Nonetheless, the applications that are already possible at these stratospheric frequencies are “mind blowing,” Rappaport told the FCC.
“Science fiction will become reality. … You will have data rates that approach the bandwidth needed to provide cognition,” and it will allow for amazing applications in robotics, machinery, communication, and computing, he said. “At these frequencies, you can sense your personal health, air quality, detect explosives and gesturing.”
The use of terahertz frequency is like “millimeter wave on steroids when it comes to the amount of signal processing that would be required,” Hays said. “If you project out from what we’re already seeing with 5G, software is likely to be front and center in solving the fundamental problems that this extremely high frequency spectrum is going to encounter.”