5G reality check: limitations and the need for 6G

Telecoms.com periodically invites expert third parties to share their views on the industry’s most pressing issues. In this piece Alan Carlton, VP of Wireless and Internet Technologies at Interdigital, takes an early look at what we need from the next generation of wireless technology.

With 5G deployments still in their early days, to many, it may seem too soon to be talking about 6G. But given the development of 5G began in 2010, now is the time for the telecoms industry to begin turning its attention to the next G.

“But wasn’t 5G supposed to be the last G?” I hear you cry. 5G was designed to be the first truly software-defined wireless standard, where network functions would be instantaneously spun-up, and new frequency bands could be quickly programmed into future ‘revisions’ of 5G networks. 5G was supposed to see real time sensing networks support autonomous vehicles, smart cities, virtual reality and augmented reality galore. But the early deployments of 5G are beginning to show some cracks, that could lead us to a breaking point.

But 6G isn’t here to re-write the script. Much like 4G was an enhancement to 3G, 6G will act as an enhancement to 5G, and will finish the work that 5G set out to do.

Reaching 5G’s breaking point

Each generation of wireless technology improves upon the capabilities of its predecessor. We’ve seen new generations that have required an entire network overhaul, like the upgrade from 2G to 3G and from 4G to 5G, along with wireless generations that have enhanced and improved on existing infrastructure, like 3G to 4G, and in due course, 5G to 6G.

5G’s hype machine has called out applications like immersive video calling to vehicle-to-vehicle communications, through to remote surgery and precision remote control robotics. These use cases will require enhanced mobile broadband (eMBB) plus massive machine type communications (mMTC) plus ultra-low latency communications (URLCC) services.

Having to deploy two or more network slices is fine for a limited number of deployments, but networking slicing en-masse is perhaps not the most elegant approach. And this is where 6G comes in. While 5G new radio evolution work like  NR-Lite are exploring mixing URLLC and mMTC, an evolution is required, providing a flexible system that can support hybrid services more organically.

5G also reaches breaking point when we look at the data rate challenges of video and immersive applications such as consumer holographic communications, telepresence and mixed reality (MR), as well as multi-sensory extended reality (XR).

While current 360° 4K video requires data rates of 10-50Mbps, next generation 360° 8K demands data rates of 50-200Mbps—beyond what 5G can deliver today. If we then think about XR and full immersive experiences, which require 200Mbps to 5Gbps—then it’s not long before 5G reaches its breaking point. And XR isn’t even the most demanding use case. Holography is the application usually mentioned when we think of futuristic video and immersive experiences, but holographic video requires close to Terabit/second data rates.

6G’s technology advancements

To get to these Gbps capabilities, then breaking into higher spectrum bands is minimally required. In fact, 3GPP has already explored 72 Ghz spectrum bands to support preliminary XR applications. But pushing into these spectrum bands doesn’t come without its challenges. When pushing into 80Ghz or 100Ghz, problems with digital design of OFDM (Orthogonal Frequency Division Multiplexing) methods appear. Which means going from 5G to 6G is likely to require a genuinely new radio design.

Intelligent metasurfaces will also be an important potential technology within 6G, as they will be able to provide a turbo boost to line speed and data rates. This involves implementing smart antennas in the radio channel that manipulate Snell’s law, and ultimately, result in introducing a new RAN element into the network that didn’t exist before.

Why now?

After all the promises and hype around 5G, cracks are beginning to appear, and the much-hyped use cases we have heard about time and time again will not be feasible with existing 5G technology.

The telecoms industry typically develops technologies 10 to 15 years in advance, which means now is the time to look at developing 6G to solve 5G’s shortfalls. 6G’s development is by no means a quick fix, and like every other generation of wireless technology, it will be many years in the making.

The relationship between 5G and 6G is symbiotic—6G cannot exist without 5G, and vice versa. 5G has laid the very important groundwork for the next generation of wireless, and it will be 6G’s job to carry it over the line.

Alan Carlton is Vice President, InterDigital Wireless Labs Organization in Europe. Alan is responsible for R&D activities in the areas of 5G and IoT. Alan has led his organization to over twenty major collaborative project and testbed wins in these areas. He founded and led the UK oneTRANSPORT initiative, one of the largest Smart City projects in the UK to full commercial launch. In 5G, Alan’s research & standardization interests include radio access network, next generation internet and advanced applications of NFV/SDN and Edge technologies. Alan has over 25 years wireless industry experience spanning every generation of wireless. Prior to InterDigital, he held senior positions at Nortel, Siemens and several wireless startups both in Europe and United States. Alan is an EEE graduate of the University of Strathclyde, Glasgow and also holds a MSc. in Communications & Signal Processing from Imperial College, London. Alan holds many patents covering a diverse range of wireless technology areas. He is a regular invited speaker at major wireless industry events including Mobile World Congress in 2017  2018 and 2019 and is also author of a wireless futures blog for Computerworld.