The significance of 6G

Henning Schulzrinne is known for speaking his mind.

A professor at the Department of Computer Science and the Department of Electrical Engineering at Columbia University, he previously expressed concern regarding what he saw as excessive hype surrounding 5G.

More recently, he has written about 6G, placing the emerging wireless standard in the broader context of societal needs.

"Research, particularly academic research, should be driven by the urgent needs of society, not just supplying patent-protected 'moats' against the competition, whether between companies or nations," he wrote in an introduction to the book, Shaping Future 6G Networks.

Schulzrinne stresses he is not working on 6G standards but has taken part in an early 6G flagship project at the University of Oulu, Finland.

"My expertise is not on the radio; it is system architecture," he says. "We have a lot of interest in my research group on issues such as automation and authentication, not specifically to 6G but to networks."

Wireless generations

Every decade, work starts on a new-generation cellular wireless standard.

In the past, each generation represented a significant change. "You started with a clean slate, the [2G] digital system had very little in common with the analogue system that preceded it, and 3G was a different beast to 2G," says Schulzrinne. "It made sense to call each a generational change."

Now, release cycles are shorter, and there are what Schulzrinne calls 'arbitrary markers', such as when the 3GPP standards body issues a new Release or when the standard is suddenly called 4G.

Now, the notion of a new generation has become forced.

There is no solely-5G handset since it also supports earlier-generation standards. Supporting multiple generations is common in wireless; Wi-Fi devices may fall back to earlier standards for a connection.

He views 6G as more of an exercise for stakeholders such as consumers, policymakers and investors. "Putting a label on it helps to crystallise efforts, primarily outside the industry," he says.

5G wireless

Schulzrinne notes how each 5G deployment still generates a press release: "You don't see that for other things where people buy stuff."

He also has doubts about some of the stated promises of 5G, such as its use to transform other industries.

"The question I don't get a good answer to is, with the digitisation of industry, does it involve a plant that had no network at all, or a minimal networking capability and they wanted to create a network?" says Schulzrinne. "Why do they choose 5G; what value creation does it give?"

In US factories, robotics is usually fixed rather than mobile. Beating Ethernet on cost is also hard, he says, and factories can be hostile environments for radio.

In China, the three main operators are showing growth in service revenues from new 'industrial digitalisation' services. But then China is an advanced, large-scale manufacturer.

"I'm trying to have an open mind," says Schulzrinne. "But where is that coming from, and what revenue is there outside of China?"

What 5G does bring is the opening up of radio spectrum, not just millimetre wave but also between 2GHz and 6GHz. 5G has also moved away from classical software to virtual network functions and cloud-based building blocks.

"This architectural transformation behind the scenes, which is hard to write flashy stories about, seems much more interesting," says Schulzrinne.

Smaller carriers, and those outside the leading industrial countries, can now outsource parts of their operation to other parties; all that is needed is a cloud provider and software.

6G: uses and metrics

It is too early to summarise 6G.

5G's main story is its three performance pillars: supporting many more devices, a tenfold hike in data speeds, and ultra-low latency.

For 6G, two stories are emerging.

One is consumer, involving the Metaverse, although Schulzrinne remains sceptical about the degree that is a motivating factor for 6G.

The second is technology related, and there are two parts here. One is AI and machine learning, although it is not clear as yet what role the technology will play with 6G.

The second, potentially transformational, is using 6G networks for sensing. For example, the position, movement and actions of entities in the field of view, adding sensing alongside the network's communication capabilities.

"It's almost like building a radar; it's not the same technology, but it's similar," says Schulzrinne. Such sensing could be used outdoors and at home as a game controller or for motion detection.

6G will improve the critical performance metrics of 5G, but Schulzrinne believes the more meaningful metrics are cost-per-bit delivered and cost-per-base station-month.

Cost-per-bit is a crucial metric if cellular wireless is to replace Wi-Fi or Ethernet networks in the home and enterprise.

The average household data usage in the US is 400 gigabytes a month, 10x more than the heaviest mobile user.

It is also why Wi-Fi is used for data offload, given that fixed-line offers a cheaper solution than cellular with its base station and mobile backhaul costs. And this is before new data-intensive applications emerge, such as augmented and virtual reality headsets.

6G’s focus should be to reduce base station and backhaul costs.

"If you want to scale up the bits-per-dollar, its going to be a big challenge making that work," he says.

Calibrating expectations

There will be a mismatch between 6G’s ambition and the likely outcome, he says.

A story told by the telcos is that they want to be the providers of higher-level services, not big data pipes. But this is misguided, says Schulzrinne. Instead, the telcos should aspire to be utilities.

"Many electric utilities, water utilities, don't grow in double-digit percentages every year, and nobody expects them to, and that's fine," says Schulzrinne. "They have an expertise and a set of skills that are necessary and helpful from a societal perspective."

Their metrics are reliability and cost-effectiveness.

He views 6G as a promising technology upgrade for the operators.

"What I want is fast and cheap, and I rely on the carrier to use modern technology to do that, "he says.

Comparing telcos to electric and water utilities can be taken too far, he says, but what the best of them share is that they provide vital input with changing technology to decrease prices and increase reliability.

They also share facing new challenges like cybersecurity.

"That is their job; it's not other things," says Schulzrinne.

Professor Schulzrinne and his research team developed the Session Initiation Protocol (SIP), the Real-Time Transport Protocol (RTP), and other multimedia signalling and support protocols.

Schulzrinne has been an advisor to the US Federal Communications Commission (FCC) and served as FCC Chief Technologist on public safety. He also served as a Technology Fellow in the office of Senator Ron Wyden, addressing data protection.