The latest symposium took a turn toward business use cases at the expense of the usual technical talks, with speakers saying that use cases should drive the technology.
Through most of 5G’s development, conference topics generally focused on the technologies such as the radio and network technologies. With much of that settled, talk moved to network-related topics such as edge computing, network slicing, private networks, and Open RAN. Today, most of the webinars and conference topics focus on business aspects.
While 6G is still undefined, universities are researching air interfaces, generally at frequencies above 100 GHz. That’s been a major topic at conferences looking into 6G for the last few years, including the semiannual 6G Symposium. The latest edition, held September 21-22, 2021, took on a noticeably different slant that previous editions — moving toward business use cases. Indeed, the Fall 2021 6G symposium included speakers who are members of Congress — not exactly engineers.
Looking at our coverage of the November 2020 6G Symposium you’ll see how the talk focused on the need for higher data rates and lower latency. Last year, we heard talks about coding at the physical layer and protocols at the network layer, both at the 6G Symposium and at the separate but concurrently running IEEE 5G++ Symposium. Both conferences featured numerous talks from university professors.
The September 2021 6G Symposium clearly had a different focus. Numerous presentations and panel sessions centered around business and use cases, though some professors did speak. Radios and carrier frequencies received less attention than at previous symposia. “Markets will drive development,” said Mike Nawrocki, VP of technology and solutions at ATIS.
Previously, we’re heard symposium speakers say how 5G is for business and 6G will be for consumers. That’s an over-generalization because we still haven’t seen enough business use cases for 5G to know where it’s deficient and what 6G will need.
Some, however, are already looking beyond 5G in terms of factory use cases. “We will need 6G to handle the billions of connected devices,” said Joydeep Acharya, senior manager at Hitachi’s Silicon Valley Research Center R&D Division. “We are looking to see how 5G can be used in factories,” he added. Even with that statement, Acharya showed how machine learning and high-accuracy based on ultra-low latency and edge computing will play roles in a post-5G network (Figure 1).
In addition to connecting devices to networks, “6G will enable more human-to-machine interaction,” said Harish Viswanathan, head of Radio Systems Research Group at Nokia Bell Labs. He spoke of the “augmented human” working in factories, healthcare, and other professions as 5G and 5G Advanced roll out. As we’ve heard in previous 6G and 5G++ symposia, the 1 msec latency promised in 5G won’t short enough. “5G did not do latency well,” said Viswanathan.
A trillion devices
With billions and perhaps a trillion devices eventually connected to wireless networks comes the possibility that networks will clog trying to move all that data. Charles Byers, associate CTO at Industrial Internet Consortium said that 5G is working well and should be viable for another decade, but it will eventually clog with data. “We’ll need more bandwidth,” he said. “Networks constantly get more users and they will use more data per user than they do today.” He spoke of a lack of spectrum and suggested that more and better fiber connectivity would help. In many areas, base stations connect to each other using microwave links. Thus, the data travels over the air at two different frequencies before reaching the wired network. Byers advocated for more fiber links and fewer microwave links in backhaul transport. He didn’t, however, address the cost of installing all that fiber, especially in sparsely populated areas.
Byers also spoke of the need for more network automation. “With so many devices coming online, we can’t afford to have people manually entering IP address into networks. We must automate that process.”
While 5G’s 3GPP releases 16 and 17 will add many features that could establish 5G as a “G” for business, it’s essentially a bit pipe to consumers. “5G turned out to be just another bit pipe,” said John Baker, Mavenir’s SVP of business development in a session focused on Open RAN. Later in the session, Baker said that 5G applications for industry are coming online.
Representing a company that provides open radio-access network (Open RAN) software, Baker cited a need for Open RAN to add network features locked away in proprietary RAN equipment from a few suppliers. Here’s where the discussion turned somewhat feisty, as Ericsson North America’s Paul Challoner, VP of network product solutions “respectfully” disagreed. “We are poised to see the promises of 5G” while adding that there will be a need for 6G.” Challoner cited limitless connectivity, lower latency, and sustainability as reasons for developing 6G that go beyond higher data rates. He describes 6G as an “Internet of senses” that could include digital touch and smell. Use cases might include robots and collaborative robots (cobots).
The Open RAN discussion then turned to standards. Baker argued that 3GPP will have to include Open RAN in future releases. “The 3GPP process is broken,” he argued. “There’s too much [RAN] lock in built into the specs.”
That’s where Challoner jumped in. “3GPP has over 16,000 items to consider in it’s releases,” he said. “One company, one vote.”
Technology gets a say
Despite all the talk of use cases driving 6G development, the 6G Symposium did cover technology. Two sessions covered air interfaces. The first focused on radios with another covering spectrum policy.
In the first session, engineers conceded that AI/ML will have to play a role in hardware design. “We haven’t had a new human-to-human interface in ten years,” said NYU professor Tom Marzetta. “People are looking for new ways to communicate and we’ll need AI/ML to develop that.” Cohere CEO Ray Dolan added that orthogonal time frequency space (OTFS) modulation, which can handle the destructive Doppler effects in wireless communications, could become 6G radio’s modulation.
While AI is making a difference today in radio design, there are still challenges, noted Samsung SVP Charlie (Jianzhong) Zhang. “In 6G, we hope create AI-intensive designs.”
Marzetta questioned AI’s ability to fully assist with hardware design, though the admitted that today’s RFICs are too complex for humans to completely handle. “Our math tools are not sharp enough at the higher PHY layers. We need AI that’s aware of Maxwell’s equations and Shannon’s theory.”
Marzetta also addressed latency, saying that the radio PHY may have to some extent abandon digital signal processing for analog processing to reduce computational time, thus shrinking latency.
Much of the talk centered on spectrum. Zhang noted the large amount of spectrum from 100 GHz to 300 GHz. Design challenges include addressing path loss and amplifier efficiency. “Mobility is also a problem,” said Emilio Strinati, new-6G program director at CEA-LETI. Aligning beams so that RF energy reaches a mobile destination is a big problem that engineers need to solve. Strinati also supports Marzetta’s point about moving to analog signal processing.
In the spectrum session, engineers further discussed using frequencies above 100 GHz. Besides the technical issues comes the cost of deploying a wireless network at mmWave frequencies and above. “Maybe we should just deploy mmWave signals indoors,” said Andrew Clegg, Google’s spectrum lead. “Most data consumption occurs indoors anyway.”
“If you don’t need the bandwidth available above 100 GHz, why do it?” said Northeastern University professor Josep Jornet, who is researching communications at frequencies from 120 GHz to 1.2 THz. He echoed Clegg’s claim that achieving mobile connectivity at such frequencies is difficult, but such connectivity could work in fixed applications such as backhaul transport. Jornet noted another advantage, saying “High data rate signals are intrinsically secure and hard to intercept.”
Even with the talk about high frequencies, we shouldn’t forget the valuable spectrum below 6 GHz. To that end, University of Chicago professor Monisha Ghosh argued that it’s time to reallocate frequencies allotted to 2G and 3G and assign them to 5G and 6G. Good luck with that, I say. Try telling that to people who use their flip phones for voice only or can’t afford data plans.