6G Adoption Rollout Will Be A Patchwork At First

Spectrum allocation, infrastructure development, and varying use cases will affect when and where this technology rolls out.

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6G is expected to begin rolling out in 2030, but advances in 5G will inch cellular technology close enough that it will make the first 6G implementations seem more like just another upgrade. That’s just the starting point, though. 6G technology gets much more interesting from there, connecting more devices at a significantly higher data rate, and enabling services that would be unattractive to consumers using today’s technology.

Many details still need to be ironed out, including the spectra various countries will allocate, the best frequencies for different applications, and the extent to which they will continue to support older technology. As advances are made, upgrades will be rolled out piecemeal over the next half-decade ahead of 6G’s official debut.

This includes AT&T’s 5G+, which is expected to boost 5G performance and increase the number of devices it can handle within a single cell site. “3GPP’s Release 17 is adding peer-to-peer communications more broadly in terms of its definition for ProSe (proximity services) and side-link communications, and this is really important for V2X (vehicle to everything), for example, said Ron Squiers, solution networking specialist at Siemens Digital Industries Software, “I don’t think the X is really widely deployed with the first instantiation of 5G. Those technologies will come into play more, especially when interacting with smart cities for V2X and V2 pedestrian, V2 infrastructure, things like that.”

There is also 5G Advanced or 5.5G. “This is an intermediate technology step that we’re hitting and designing for today that gets us to the additional spectrum and promises — the things that 3GPP had intended to deliver — and which people were not designing into their networks en masse because of compatibility concerns,” said Shawn Carpenter, program director 5G/6G at Ansys. “That will ease consumers’ concerns about being shaken into another technology node where they have to pay for yet another phone. We need to be thinking cleverly about how to bring along the legacy equipment and continue to design for compatibility. Most of the world has gone to 5G, and as we transform to 6G we’re going to be faced with a similar set of issues. The people who will become very successful in this field are the people who can engineer the breakthroughs of 6G into a format that still allows and enables subscribers with five-year-old mobile phones to have decent service. That compatibility is going to be a constant pressure on the organizations trying to roll service out.”

Putting this in perspective, 6G will add much greater reliability and ultra-low latency in nearly real-time data transmission, underpinning a new generation of vertical applications, especially for Industry 4.0. In contrast, 5G will be able to fulfill different requirements due to planned increases in data throughput, and higher bandwidth. That includes providing critical traffic information in a car and video streaming in just one physical network, through “network slicing” or utilizing private networks operated by a public operator or any new private service provider.

Eventually, 5G will automate and connect everything with everything else through the IoT and the Industrial IoT via mobile radio, according to Infineon. The 5G Advanced node will include multi-user massive MIMO in C-band and mid-band frequencies. So by the time 6G really takes root, it will enable the as-yet to be delivered promise of 5G, along with more sophisticated edge AI.

“The dominant communication paradigm will be machine-to-machine, and the edge is playing there with robotics, infrastructure, smart cities, and Waymo taxis running around San Francisco,” said Siemens’ Squiers.

In fact, 6G could be the first generation in which machine-type communication is more important than human-type. “Edge compute among the machines is going to truly be prevalent and scalable and widely used across many different verticals,” said Mung Chiang, president of Purdue University, recent recipient of the IEEE Founders Medal. “The usage challenge includes how we think about the different application domains beyond human interactions and use requirements.”

Fig. 1: Intermittent machine-to-machine communications in 5G New Radio (NR) and expansion to 6G. Source: Purdue University 6G Global Roadmap Taxonomy Report

Spectra and frequency challenges
Traditionally, it took about 10 years for each new generation of mobile to be developed and rolled out, but cycle time is compressing. It’s now taking about five years between the full realization of the International Mobile Telecommunications (IMT) targets set for Mobile World Congress and other venues for mobile technology.

One technological aspect that will need to be ironed out involves the spectra for each region. “The spectrum is a very complicated question in terms of how our spectrum is going to be reformed in the sub-6 GHz domain to support both 5G and 6G going forward,” Squiers said. “The NTIA (National Telecommunications and Information Administration) and FCC (Federal Communications Commission) manage what spectrum gets used in the U.S., but that all has to get negotiated via treaties with world organizations like World Radio Conference (WRC), and through the IMT 2030 those negotiations are ongoing. For example, WRC has agreed to allocate the 7 to 8.5 GHz band for 6G in the 2027 timeframe, but it’s changing constantly.”

The sub-terahertz and terahertz bands, encompassing frequencies between 100 GHz and 10 THz, will be crucial in developing 6G and beyond. “These frequencies will complement the lower frequency spectrum, including sub-6 GHz, midbands, and millimeter waves. Terahertz communication for 6G offers a considerable bandwidth, which can effectively address the spectrum scarcity challenge currently faced by wireless networks. This opens up exciting possibilities for wireless terabit-per-second (Tbps) connections,” as noted by Cadence.

Fig. 2: The frequency spectrum range for 5G and future 6G applications. Source: Cadence

“Probably 2030 to 2035 is when we’ll start to see the true rollout of 6G equipment,” said Ansys’ Carpenter. “The things that are coming in 6G, in particular, are a lot more spectrum. The WRC and FCC are exploring additional and alternative frequency bands, including an upper mid-band. That’s creating some issues with the military, who have to vacate parts of that spectrum to allow it to be used for businesses.”

How complex the 6G rollout will be is not entirely clear at this point. “If 6G is more energy-efficient, then it will replace 5G, but this is not clear yet,” said Andy Heinig, head of department efficient electronics at Fraunhofer IIS/EAS. “Currently, each new standard needs more energy, and from that perspective it makes sense to stay on the older ones. In Europe, we have this problem that very old ones are switched off because of the frequency band, which is needed by other standards, so the very old ones are replaced. I would expect that if you stayed at 5G, maybe the IP costs of 6G are higher at the beginning, and this is something that the end customer or provider of the technology will need to pay for.”

More millimeter waves needed
Higher frequencies supporting millimeter wave technologies are needed to realize the true potential of 6G. “Maybe it’s a mix-and-match of different technologies,” said Heinig. “If we go to 28, 34, 38 GHz, that’s only reachable with more specific technologies, and that also makes it more expensive. The other side is that you need more digital processing, or data processing. You need more types of chips to meet the frequency requirements if you really want to use this new band. I don’t know if it makes sense to go to 6G without using this new frequency band. But then you need this new chip technology, or you need more chip technologies.”

From a chip design perspective, there are numerous upcoming bands — 28, 38, 40-something, and even 60 GHz. Supporting all of them will be a challenge. “Maybe in the end only one or two bands are selected,” Heinig said. “Maybe there are also problems with interoperability around the world, and you need one of the bands in one country here, the other one in the other country. You want everything to be very flexible. This multi-physics problem is definitely something we see here because of the highly integrated systems that are needed.”

At one time there was hope that ultra-wide band at the millimeter wave band would work well in the 28 and 39 GHz bands, but this may be changing. “We’re now watching providers like AT&T, Verizon, and T-Mobile let their spectrum licenses expire in those bands,” said Carpenter. “A few years ago they paid billions of dollars to get access to that spectrum, and today they aren’t even keeping those spectrum licenses alive because they’re finding it so costly to install and develop the millimeter wave band equipment. And then, the coverage distance is considerably shorter. You go up 10X in frequency, your coverage range shrinks the radius that you can cover effectively, and that bandwidth shrinks by a correspondingly 10X distance. So what do you do to overcome that? You have to densify. You’ve got to put more access points in more base stations, which is incredibly costly. Then at millimeter wave bands, to produce the RF energy, you’re creating a lot more heat. You’re wasting more energy and heat because the electronics are more challenging for RF and millimeter waves. For all of those reasons and more, ultra-wide band is turning into something that is probably going to be used for more focused applications, like stadiums, train stations, and subway stations — places where you have a really high density of people who have line of sight visibility to the antenna system, so that you don’t have a lot of echoing off the environment, a lot of multi-path to confuse the receiver and to self-interfere. There will still be a place for that, but the licenses and the needs and the use cases will be focused on these high-density, high-population, open-space areas.”

Spectra also must be decided for the latest Wi-Fi protocols. “Wi-Fi 7 opens up the 6.0 spectrum, which is under regulatory review in several geographies of the world, but it has been approved by the FCC here in the U.S.,” said Ananda Roy, senior product manager, low power edge AI at Synaptics. “Europe took a big step where it made available, if not the full 6 GHz spectrum, a chunk of it for Wi-Fi operation. Certain countries in Asia have also opened it up, like India and Japan. China has yet to open it. The future of Wi-Fi is going to be operating now from only two bands, which is 2.4 GHz and 5 GHz, but also in 2.45 GHz and 6 GHz. That enables bringing more devices into a Wi-Fi network, bringing more intense applications. Let’s say you have homes right next to each other, hotels, multi-dwelling units. You can have a lot more coexistence of multiple Wi-Fi devices in proximity of each other. That shifts the paradigm from only a few devices, which was Wi-Fi 4 and Wi-Fi 5, to 20 or 30 devices in Wi-Fi 6. Now you have a few hundred devices operating in close proximity. That’s the role that 6 GHz will play.”

Technology uptake
How quickly new wireless technology gets adopted is highly variable. This is evident with 5G, which has seen vast differences in different countries and different sectors of society, and it may be even more so with 6G.

“If you live in China, where you have a top-down directed government and industry partnership, you literally can build a smart city overnight,” said Siemens’ Squiers. “In terms of rolling out the full promise of 5G, I would say it’s definitely materializing in China in terms of what capabilities are coming into fruition. In the U.S., I don’t think the promise of 5G has been fully realized. There are segments that have been realized for mobile broadband and some of the telemedicine capabilities for ultra-reliable communications. Probably the best case for 5G meeting the promise is the machine-to-machine type communications in the factory. We’ve done a good job of trying to integrate 5G, especially 5G private networks, into the factory setting for automated guided vehicles and talking to factory robots. That’s only going to accelerate based on the current climate in the United States. We’ll see more of that happening in the short term rather than long term.”

There are multiple reasons for slow uptake. For one thing, there are more telecommunications options in some highly industrialized countries. “Also, the regulatory environments don’t make it easy for operators to stick an antenna anywhere they want,” said Squiers. “There’s a process of getting the land, putting in cell towers, and augmenting them to support the new antennas which are a must-have for the new spectrum required for 5G. Many towers look like a Christmas tree, where they’ve hung more antennas on the existing towers. Also, I don’t see the small cell deployment as rapid as had been thought in terms of the office space. I see Wi-Fi deployment still being dominant throughout industrial enterprises. 5G is supposed to start supplanting that in some areas, especially in high-rise buildings, but more of that needs to happen over time.”

Ansys’ Carpenter agreed regarding infrastructure as an issue. “The 5G system is a holistic package of data transport, antenna systems and all that technology, but also includes things like service provider machinery for billing. Particularly in North America, we’re dealing with an infrastructure problem that we had when the entire cellular revolution took off. We had this infrastructure of copper in place, and it wasn’t cost-effective to jump into cellular with both feet because everyone still had a telephone in their home. That wasn’t necessarily true in more emergent cultures or emergent areas of the world, where they lacked that infrastructure. They didn’t have to put any copper down. They could go straight to wireless technology. That’s the problem we’ve been seeing here in North America. We have this fairly extensive investment in 4G communications, and even in some of the early 5G communications, but the emphasis for the carriers here in North America — and probably Europe, as well — is to add the 5G service, but make sure that we don’t alienate anybody using 3G services and 4G services and 4G LTE. That wasn’t necessarily the case in other cultures where they hadn’t built up and invested that heavily yet in 3G and 4G technology and weren’t forced to make sure they maintained a compatibility with older devices.”

To date, there has been an implementation of combined 3G, 4G, and 5G, which has had to be separated from some carriers’ 5G standalone [5G SA] services, Carpenter explained. “Some customer service providers have had to rip out and replace legacy equipment, in which they had a sizable investment, and put the full 5G standalone equipment in to realize the power of all the things that are in the current 3GPP definitions of 5G.”

One company that has gone all-in on 5G is T-Mobile. “T-Mobile chose not to fight with the compatibility issue, and really pushed ahead with a strong, clear focus on 5G functionality,” Carpenter noted. “Their subscribers today are seeing services that seem to be registering high customer satisfaction rates. They’re seeing good bandwidths. They’ve got pretty good coverage across the country that didn’t come without some pain. They had to make a really determined effort to push ahead and put that equipment in place and not worry so much about backward compatibility. Today they’re reaping the benefits, and we’re seeing some of the other carriers run to catch up to that.”

In general, faster deployment could drive higher adoption in America. “A lot of the applications are trial-and-error processes,” said Purdue’s Chiang. “Nobody can get quite right how people are going to use it or how machines are going to use it. You need to just deploy and pivot, and you’re going to learn from the deployed technologies, just like back in the early to mid-’90s. Because of the internet deployment with the routers and DSL-style broadband back then, we were able to support applications. Yahoo, Amazon, Google came a few years later. Then people started to learn how to provide value on the application layer. That’s because the physical and the Mac layers got deployed.”


Fig. 3: 6G technical focus areas organized by primary target deployment environment. Source: Purdue University 6G Global Roadmap Taxonomy Report

For the foreseeable future, adoption of 3G through 6G will remain patchy. “In some cases you can maintain all of them, and in some cases you have to sunset 3G,” said Chiang. “Then you go to a different country and say, ‘Fine, you only get 4G LTE, and you pay me less, as well.’”

In some countries the delay may even be due to public fear of new RF signals, towers, and antennas. “Public education is going to be crucial to help people understand what they are actually being exposed to and what the dangers are,” said Ansys’ Carpenter. “What’s the leading research on how strong those levels are? One of the things that I’ve tried to help some of my friends understand is that the mobile phone you put next to your head is irradiating your body with a lot more intensity than any number of cellular antennas you see up there, unless you’re really close to that cellular tower. The cellular tower radiates a total of maybe 100 watts. A phone will, at its maximum, radiate two tenths of a watt or a quarter of a watt, but you have it right next to your ear. So if you’re particularly concerned about that, go get your earbuds and keep the phone away from your head.”

Conclusion
Though 6G networks likely will be complex and expensive, use cases are certain to emerge that will become as indispensable as the internet is today.

An enormous amount of bandwidth is needed to be able to sustain futuristic kinds of paradigms, such as VR holograms, noted Siemens’ Squiers. “Not having 6G means giving up on those kinds of goals and business opportunities. I don’t see that happening. 5G was a big step. We did achieve a lot with it. As with anything, these things are a continuum. It’s not necessarily a step function between one version of 5G and then the next version is 6G. It’s going to progress over time as breakthroughs and technology happen.”

There’s an incredible future coming, Ansys’ Carpenter agreed. “It’s probably going to come from a dorm room at MIT or the Indian Institute of Technology, or from one of the brilliant universities in Europe or Southeast Asia, but there are coming applications that will need all that compute power. This is the world of apps. In app development, there will be killer apps coming that will absolutely drive virtual reality meetings, so that you have a physical realization of 3D groups of people meeting together in concert. It’s unfathomable to us right now, because we’re used to the limitations of what we have today, just as it was for people pre-internet. We need to keep an eye on what’s going on in those startups with those really smart entrepreneurs — particularly the young engineers who aren’t shackled by limitations yet, because they haven’t been working with the limitations to get used to them. They’re the people who are going to be developing those killer apps that are going to drive 6G. When those come along, you’ll see an uptake. It won’t be an option to not get on that train and roll that out. We can’t imagine what’s coming, but something’s coming to break the paradigm. Something is coming that will drive that space and make it absolutely necessary.”

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