5G is the next big thing, expected for roll-out around 2020 – but preparations are being made right now and have been since even before the introduction of 4G. In this special report, Abi Millar asks Chris Bilton, director of research and technology at BT, what mobile network operators’ plans are for the migration to 5G and unpicks the areas that pose the greatest challenges.
To the uninitiated, the dawn of 5G might sound like a linear development. With 3G first appearing in 2001 and 4G systems fully standardised by 2012, the fifth generation of mobile network is expected to roll out in the early 2020s. It will be a new mobile generation for a new decade, just as we might have envisaged.
However, the predictable timing belies the unprecedented pace of change. 5G is expected not just to build on what came before but to shake it up entirely, facilitating not only faster internet connection but also the so-called 'internet of things' (IoT).
In essence, because data connection will be so speedy, the likes of self-driving cars, bins that tell you when they need emptying and trains that indicate their free seats will become feasible on an extended scale. If 4G is all about superfast broadband, then 5G will be about creating a hyper-connected world.
As Chris Bilton, director of research and technology at BT, points out, the technology looks poised to be genuinely transformative. While BT has long been in the vanguard of change - launching the UK's first always-on broadband service in 2000 and currently making headway in the 4G market - there has never been a time like this for the telecoms industry.
"The 5G vision is for flexible, reliable and secure wireless networks to connect people - and things - with applications and services enabling an era of the 'mobile internet of everything'," he explains.
The need for a faster network is not in doubt. Even aside from utopian-sounding predictions about smart cities, there has been a huge rise in subscribers to mobile networks. Current forecasts from GSMA Intelligence suggest that the total number of unique mobile users will increase from around 3.6 billion at the end of 2014 to 4.6 billion by 2020, and the number of connections will rise from around 7.4 billion to nearly 10.0 billion - the figures stand at around 3.8 billion and 7.6 billion respectively moving into 2016.
Much of the latter increase is due to machine-to-machine (M2M) connections, which are expected to climb from 3.7% of the total in 2014 to nearly 10.0% by 2020. M2M communication will be especially important in the years to come, as it provides the basis for the IoT.
Data traffic is also growing rapidly. Fuelled by the growth of mobile video, particularly HD, it is expected to register a ninefold increase between 2014 and 2019, surging from 2,500 to 24,000 petabytes a month around the globe.
As Bilton explains, today's mobile networks are facing challenges in three key areas. Firstly, 5G must support a step change in the total number of connections allowed on networks. Secondly, HD video streaming requires a higher throughput; the target for 5G is 10Gbps peak data rates and 1Gbps average, with 50Mbps everywhere - a huge step up from the 15Mbps that is typical for 4G today. Thirdly, it requires lower latency, defined as the time lag between an action and a response.
"The latency on a 4G network, 50ms, is half of that of a 3G network," he says. "However, applications such as self-driving cars and haptic feedback still require further improvement. The target for 5G is 1ms - though, at present, the exact measurement parameters for this are still being defined."
Playing the long game
Such kinds of figures may sound far-fetched for now. Given that current 5G mobile devices are fridge-sized and need to be moved around on wheels, it will take some time before the technology can fit in our pockets. What's more, we currently don't have much need for the levels of performance it offers. While it would be nice to download an HD movie in a couple of seconds, necessary applications for 10Gbps data streaming have, for the most part, yet to appear. However, this was also said about the need for high-speed broadband services in the 1980s and, today, 80Mbps to-the-home speeds are commonplace.
5G, however, is about planning for the long haul, including the notional needs of the 2030s and beyond.
A number of applications have already been identified as targets for 5G. These not only include HD video streaming, which will ultimately evolve into virtual reality and immersive experiences, but also the so-called 'tactile internet', which has been pegged as enabling scenarios like remote surgery, and the mission-critical IoT, with its applications in healthcare settings. These kinds of services will depend upon high-speed, low-latency, ultra-reliable connections, not to mention a low-energy footprint, cost-efficiency and excellent battery life.
"5G technology is not expected to be deployed until 2018-20 and must have a lifetime of 15-20 years. Therefore, setting aggressive targets is essential," Bilton says.
Of course, in order to meet these targets, researchers will need to do more than just build on 4G. While new radio technologies, with more efficient waveforms, may meet the new throughput needs in part, the real solution would seem to lie in altering the very network architecture. In order for 5G to become a reality, the radio frequency spectrum will need to be restructured.
"The lifeblood of wireless networks is radio spectrum, which will remain a limited resource," says Bilton. "Larger gains will be achieved through 'densification' of radio networks as smaller cells are deployed to provide local, high-capacity coverage.
"In turn, this will drive network convergence - with the widespread deployment of fixed connections to support the proliferation of mobile small cells."
Anticipating a future of small cells and ultra-dense networks, BT is researching a number of topics in this field. "A self-organising network [SON] will be essential for the millions of small cells," says Bilton, "and enabling cloud radio access networks [RANs] over Ethernet 'mid-haul' will become an essential technology for cost-effective deployment of cells. We are in the process of undertaking proof-of-concept studies and planning trials in these areas."
He thinks that other key technology themes will become important too, not least the evolution to a software-based, virtualised system, in which multiple 'virtual networks' are created within the overall network to support different service types.
Ultimately, 5G technologies will use different frequency bands - the current licensed spectrum, unlicensed spectrum and millimetre-wave (extremely high-frequency) spectrum - with the first use of these ranges for 5G set to come into use around 2020. In the future, when 5G is working across all three spectrum ranges, devices will be able to choose which of the three they use, to ensure a smooth flow of data traffic.
While research into 5G is under way across the globe - South Korea started its R&D project as early as 2008 - the UK has proven to be one of the pioneers. Anticipating the future benefits for science and technology, the UK Government has made the new network a priority.
September 2015 saw the opening of the 5G Innovation Centre (5GIC) at the University of Surrey, the world's first research centre set up specifically for 5G mobile research. A collaboration between academics and industry partners, including BT, the institute will eventually house 170 researchers, with expertise in communications, the IoT, 'future internet' and 'connected cars'. It has received £12 million of government funding, along with more than £68 million of co-investment from its industry and regional partners.
"The 5GIC will help to define and develop the 5G infrastructure that will underpin the way we communicate, work and live our everyday lives in the future," says Bilton, who is BT's representative on the 5GIC advisory board. "It has been set up to drive the delivery of mobile communications and wireless connectivity capable of meeting the needs of tomorrow's connected society and digital economy."
At the heart of the 5GIC is a state-of-the-art test bed that, at 4km2, is the world's leading independent bed for trialling emerging 5G ideas. Currently, it equips researchers with an advanced 4G network but, over time, this will be upgraded to a fully fledged 5G system. The intention is to enable the development and testing of 5G prototype technologies in real-world situations. With work under way in seven key areas, the centre's research covers most of the topics relevant to 5G, from the physical layer/air interface research right up to the application/service layer.
"Collaboration is essential, as there is strong interlinking between the work areas," says Bilton. "For example, small cells and ultra-dense networks will be required to meet the capacity demands on 5G. To enable this, SON capability will be essential for the millions of small cells so that they can manage themselves and provide efficient coverage and capacity. You cannot research one in isolation of the other."
From an international standpoint, the next phase of 5G research will be standardisation, led by the 3rd Generation Partnership Project (3GPP) organisation. At the latest conference in September 2015, 3GPP discussed the time frame for development of the standard: the first phase of specification will be completed by the end of 2018 and the second phase by the end of 2019, meaning 5G will be defined by 2020, when limited early roll-outs of the technology are likely.
With work continuing apace, Bilton anticipates that researchers are likely to run into a number of technical challenges. The first issue will be keeping the complexity low enough to ensure that costs are kept down. For 5G to really take off, and find appropriate uses, it will need to be simple and efficient.
"We need to manage the complexity of having many different radios, some operating in licensed and some in unlicensed spectrum, and integrate this with legacy networks and Wi-Fi so that the customer has a simple, and great, user experience," he explains.
They will also need to find a way to harmonise the various technologies being used. If you develop a multigigabit, low-latency bandwidth today, it is going to be energy-intensive. The question is how the power demands can be reduced, making the technology suitable for an eco-friendly IoT.
"We need to design architecture flexible enough to cope with realistic backhaul yet take advantage of ideal backhaul where available," adds Bilton. "And we need to manage interference and client handovers/signalling in a network with millions - rather than tens of thousands - of base stations."
In the long run, working through these challenges, will be not so much desirable as necessary. With game-changing implications for almost every aspect of modern life, 5G is about far more than just improving download speeds or removing glitches. As a result, everyone from service providers to chipset vendors has an important stake in the outcome. At this stage of research, the goal is collaboration, not competition, with the top minds in the field working together to pool their strengths.
"The continued development of the digital economy, based on network access anywhere at anytime, is transforming the telecoms industry," says Bilton. "It is important to obtain the different perspectives and skills of the different players in the value chain as, if 5G does not work commercially, there is no point in delivering a technical solution."