LiFi: past, present and future
Written by: Philip Mason | Published:

Inventor of LiFi Harald Haas talks to Philip Mason about the origins of the solution, and why he believes it will solve the problem of finite RF spectrum in a data-hungry world

As recent readers of Land Mobile will know, the digital communications sector is currently in a state of high anticipation, waiting for the maturation and widespread roll-out of potentially transformative technologies such as 5G, AI and so on.

As disruptive as these solutions will undoubtedly prove, however, perhaps the most intriguing of all is LiFi, which enables users to communicate using the visible light spectrum rather than radio frequencies. Not only is this – at least as far as your correspondent is concerned – pretty clever, it may also prove to be the single most elegant, not to say useful, answer to a pre-existing problem since the Babel Fish.

The inventor of LiFi, as well as founder of attendant technology company pureLiFi, is Harald Haas. Discussing the origins of the solution, along with the rationale behind its initial development, he says: “I started my career at Siemens’ mobile communication network, leading a research project around the year 2000, that was geared essentially towards developing a patent portfolio for what is now 4G/LTE.

“Obviously, the smartphone didn’t exist at the time, but it was clear even back then that if and when mobile multimedia took off, the available radio spectrum would not be sufficient to cope with the demand from consumers. That’s when the idea for LiFi first started to formulate.”

He continues: “Following my time at Siemens, I was able to secure an academic post at Jacob University in Bremen, which gave me a lot more freedom to explore ideas and think out of the box. At the time there was a lot of conversation going on about using white LEDs for data communication, which triggered some deeper thoughts on the subject from our point of view. Along with my undergraduate students, we started to work on the basis that there is a huge amount of unused spectrum available in the light domain.”

Following this initial work in Bremen, the technology continued to develop to the point where Haas was invited to address the 2011 TEDGlobal conference taking place in Edinburgh. Several iterations of the technology have followed since then, with PureLiFi attempting to develop increasingly intuitive ways to integrate the solution into the commercial digital communications ecosystem.

With that in mind, the most recent leap forward for the company was from a laptop-compatible dongle to a Gigabit module, as demonstrated for the first time during this year’s Mobile World Congress. According to Haas, these are now ready to be designed into consumer mobile devices once the market is ready.

Going into greater detail about the principles behind LiFi itself, as well as the difficulties presented at the beginning of the project, he says: “The core obstacle we identified first of all was that, unlike RF, light communication really only has access to one channel, dependent on the ‘intensity’ [ie, the rate at which light energy is delivered]. This fundamentally limits the data rate that is available across the system, in a way that does not happen with radio frequency.

“That being the case, the only way to encode information within a light source is by changing the brightness itself – in other words, by flickering the light. That kind of modulation is the only method through which we can inform the receiver of changes going on in the transmitter.”

The solution to this problem, according to Haas, has been the use of OFDM (orthogonal frequency-division multiplexing), a signal modulation technique through which single data streams can be encoded on multiple carrier frequencies.

“The laws of physics don’t allow us to ignore the inherent limitation of light when it comes to communication,” he says. “But we have found a way around these difficulties, through the use of signal processing techniques, almost like a machine-learning algorithm.”

From an external infrastructure point of view, LiFi operates through the use of LED fittings, for instance in the form of ceiling-mounted strip lighting. These in turn are linked to a network access point, with the LiFi signal available to anyone using a compatible device sat within the illuminated area.

This will likely make it an intriguing solution for those looking to roll out digital communications infrastructure within an office space, if only because of the hyper-efficient, ‘directed’ nature of the coverage. At the same time, as Haas is quick to point out, it also has benefits from a security point of view, given that – again, quite unlike RF – it is physically impossible for data communicated via light to travel through walls, and potentially into the hands of an unscrupulous party.

Hold up, wait a minute
As mentioned, the initial driver for the development of LiFi was Haas’s sense, back at the beginning of the 2000s, that as the LTE consumer market developed, available RF spectrum would become increasingly precious. This is something which continues to be borne out as of 2019, both with the public now demonstrating an almost pathological need to consume ever-increasing amounts of data, and MNOs cutting each other’s throats over every scrap of spectrum that becomes available.

Discussing this, Haas says: “From a societal perspective, the widespread adoption of LiFi is inevitable as far as I’m concerned – it has to be. It’s only a question of when, which in itself is something we’re getting a clearer understanding of on a daily basis.”

He continues: “As well as being a viable solution in its own right, LiFi also provides what is essentially a pressure valve for Wi-Fi by taking a huge burden away from it. We see our solution very much as an addition rather than a replacement, providing vastly increased throughput because of fewer [network] packet collisions when both are operating in the same space.

“With LiFi, we’re also eventually predicting a level of data provision in the 10 Gigabits-plus region, which is something that just can’t be achieved with parallel technologies.”

That being the case – and, given the zeal with which Haas speaks on the subject, there is no reason to think that it won’t be – you have to ask yourself what the hold-up is. Why is the deployment of LiFi technology currently limited to 150-plus testbeds rather than in workplaces across the globe?

One simple answer to that is the caution with which the market tends to approach high-investment/high-reward solutions, particularly when their roll-out would require nothing less than a wholesale paradigm shift in terms of not just infrastructure but device manufacture. The natural extension to this, meanwhile, is that, as with the truly disruptive aspects of 5G, the business case hasn’t quite yet been fully proved, despite the fact that – in the case of LiFi – the technology itself is pretty much ready to go.

Discussing what is required for the next step to take place, Haas says: “Ultimately, we’ll need a rich ecosystem of integrators, OEMs, software developers and so on, all of whom need to operate in concert with each other. This is a lengthy process.

“At the same time, the technology within the eventual ecosystem itself needs to be interoperable, which is the basis on which we’ve worked since the beginning. That was the big success of GSM and the mobile communications MOU back in 1987, and we need a similar approach in this context. We currently sit on the 802.11 Wi-Fi standardisation group, and there will be a ratified standard by 2021.

“Once LiFi is in a commercial device via our chipset, I see a similar transition as we had with smartphones. We have significant interest from device manufacturers as we speak, and we’re already talking about use-cases such as machine-type communications, where we wouldn’t necessarily even need an external infrastructure at all.”

LiFi is just one of a number of disruptive digital communications technologies that are currently waiting to be fully exploited by both the industry and society at large. The results once it is fully rolled out could be profound.

CV – Harald Haas
Professor Harald Haas founded pureLiFi – together with his former postdoctoral researcher, Dr Afgani – in 2012. He is currently the chief scientific officer of the company, as well as director of the LiFi Research and Development Center at the University of Edinburgh. He has given two TED talks, which between them have been watched more than five million times. In 2011, LiFi was listed among the 50 best inventions in TIME magazine.

Haas is a fellow of the Royal Society of Edinburgh, as well as of the IET, and of the IEEE. He has held a Royal Society Wolfson Research Merit Award since 2017, and is the recipient of the James Evans Avant Garde Award of the IEEE Vehicular Technology Society.

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