Interview with the inventor of LiFi – Prof. Harald Haas

Things are already getting cramped up in the ether: Wi-Fi, ZigBee, mobile networks, RFID – whatever the various wireless technologies are called, they all have to share the very tight bandwidth of radio frequencies. This means that ever fewer free channels are available for the rapidly growing flow of data – and there is an increasing danger that the various wireless technologies will start to interfere with each other.

Around 20 years ago, Harald Haas had a lightbulb moment in the truest sense of the phrase. Why not use the spectrum of visible light to transfer data? After all, lights are already installed in every house, every office and every production hall. Haas, who is now a Professor at the University of Edinburgh, has since developed his original idea into a marketable technology called “LiFi”.

An electrical technician by trade, creativity is essentially part and parcel of being an engineer in his view. According to him, becoming an engineer in the first place is about wanting to build something that changes the world for the better. It follows, then, that he founded his own company, pureLiFi, once his ideas were developed enough to be marketed.

What is LiFi?

LiFi Definition
LiFi (short for “light fidelity”) modulates the light of LEDs, such as those installed in ceiling or wall-mounted lighting systems, which enables information to be encoded. Photodiodes which demodulate the received light serve as receiver devices. The devices which transmit and receive data must always remain in visual contact with each other. As a result, it is impossible to transmit directly through solid walls, which in turn makes it impossible to intercept transfers outside one single room.

Scotland is perhaps better known for its rugged landscape and fine whiskies than for high-tech products. How did it come to be that LiFi – a technology which is poised to turn the wireless world on its head – was developed here of all places?

Harald Haas: The foundations had already been laid in Germany, in actual fact. Back when I was working on 4G at Siemens Mobile Communications Network in Munich, I quickly realised that the bandwidth of radio frequencies would no longer be sufficient in the future. In 2003, I moved to Jacobs University in Bremen and started to occupy myself with light-based communication more intensively.

Here, we achieved one success after another; things got more and more exciting. In Edinburgh, I was then able to continue my work in this field with support from local business-development funds.

Jacobs University
Jacobs University is a private, state-recognised university in Bremen and one of the most international universities in the world. Founded in 2001, the university attracts highly talented and broad-minded students from all over the world. More than 1,400 students from over 100 countries currently live and study on the campus, where they are prepared for international careers in economics and the sciences.

Why did you move to Scotland?

H. H.: In my opinion, Scotland boasts a wonderful academic landscape that maintains a good balance between teaching and freedom for research. The University of Edinburgh is well regarded and sits very high up in global rankings. We have good students, a good environment, good research funding and the ideas to match!

Can the rest of Europe take a leaf out of Scotland’s book in terms of research work?

H. H.: I think so, yes. Ideally, it would be possible to combine German precision and the tendency to consider things down to the very smallest detail with the creativity and the possibilities that abound here. Germany is good when it comes to fine details – and world-class when it comes to development and elaboration.

However, it’s often the case that the initial ideas come from elsewhere. I think that creativity and the courage to tread new paths are more pronounced in Anglo-Saxon countries.

In other words, it would be ideal to gain experience in both countries…

The polar opposite of Brexit would create something worthwhile, which is what the United Kingdom has failed to understand. I would advise politicians that all Europeans should spend at least two years living abroad in a different European country at least once during their lifetime. It is definitely worth broadening your horizons and seeing things that you’re not used to.

By doing so, you get to see what’s good at home – but also what’s good elsewhere. Once you come to that realisation, you can combine those things and continue to improve them. That’s far better than raising the drawbridge.

How did you first come up with the idea of transferring data using light?

H. H.: Light forms part of the electromagnetic spectrum but has a much larger bandwidth than radio waves. For radio, this amounts to approximately 300 GHz; for light, it is more like 200 THz. I wanted to tap into this spectrum to transfer data. My aim was to apply the modulation techniques used for wireless radio technology to incoherent light. In the meantime, we’ve achieved a transfer performance of over 12 Gbps – a data rate which is almost twice that of the fastest Wi-Fi. To do so, we use four normal LEDs, such as the ones sold by EBV for less than 50 cents in total.

How far along is the technology today? Is it already time to talk about commercial viability?

H. H.: Absolutely! LiFi has been on the market since 2012. It already exists in its fourth product generation.

LiFi-XC from pureLiFi is a dongle which makes any computer LiFi-capable. The dongle is connected to the USB port and facilitates high-speed communication at a rate of 43 Mbps.

In the meantime, we have realised access points together with partners such as Lucibel in France. Our LiFi dongle has also already been integrated into a smartphone case. This then enabled us to conduct a Skype call at the Mobile World Congress 2018 in Barcelona. The automatic handover of the smartphone from one LiFi diode to the next enabled us to pass through the room and continue the call without any interruptions. The connection is bi-directional; it provides an infrared uplink, and we are well on the way to miniaturising the system further. In the near future, this will enable us to integrate LiFi directly into the smartphones themselves.

As early as the end of 2016, Lucibel produced the first LiFi lighting fixture capable of 42 Mbps.

Can you imagine using the technology in a wide area network?

H. H.: We have already developed a system of that kind; we call it “backhaul”. The technology behind this is based on infrared laser systems which connect two locations in a point-to-point fashion. That distance may be as little as one metre or may equally extend over a range of hundreds of metres.

However, we were able to achieve a further breakthrough in the last three years by using solar cells as LiFi receivers. If the photon flux varies over time – as in the case of LiFi – the amount of energy generated by the solar cell changes. Information can be encoded in these fluctuations of intensity. Consequently, a solar cell can simultaneously serve as a LiFi receiver and an energy harvester. We have already been able to transfer 500 Mbps per cell using the latest solar-cell technology from a Fraunhofer research institute in Germany. One solar panel is made up of many such cells. If we then apply the MIMO procedure, we can achieve a linear increase in data rate that corresponds to the number of elements in the solar panel. As such, we achieved 5 Gbps on a panel comprising ten cells. We would be able to use every solar cell on a given building as a receiver by implementing this technology. In combination with laser systems, this would enable high-speed Internet to be rolled out to even the remotest regions. In the meantime, we’re working on building a solar-cell-based backhaul of this kind in the course of 5G expansion with funding from the UK government.

Where do you see the trends that will drive forward the use of LiFi?

H. H.: The most important driving force is surely the trend towards a data-based economy. Industry 4.0, autonomous systems, smart cities – all of these developments require connectivity. Yet the capacity of existing wireless systems will not be sufficient for future requirements. You can already witness this “spectrum crunch” today – at the airport, in a stadium; essentially anywhere a lot of traffic is generated by a lot of people simultaneously. In such instances, LiFi not only offers enormous capacity, but also increased security. Those are its decisive aspects.

Market analyses do predict enormous market growth for LiFi, in fact. How does it feel to have invented a technology which is poised to turn the entire market on its head?

H. H.: It’s exciting – and also what has got us out of bed in the morning for the past 15 years! Initially, my vision was only to generate additional data links using light. However, upon closer examination, applications opened up in many markets, including 5G, defence, IoT and Industry 4.0. In some respects, this also poses a problem. After all, we need to focus our efforts appropriately from a business perspective. Today, we are concentrating on the opportunities which can be most quickly and profitably implemented.

Throughout this process, how do you manage to stand up to the major high-tech firms from the USA?

H. H.: We’ve been working on LiFi for 15 years and have built up a very strong portfolio of patents. In addition, our status as a small company and a relatively small research institute makes us more agile than our larger counterparts. For LiFi, we now have over 70 pilot projects running in various fields in order to test the technology in different markets and applications. In doing so, we are striving to continue leading the charge.

Market Researches
Global Market Insights estimates that the global LiFi market will be worth USD 75.5 billion in 2023. (Market Research) Energias Market Research calculates that the market volume will be a little over USD 80 billion in 2023. Compared to 2016, this would represent average annual growth of 74.6 per cent. (Market Research)

A market analysis conducted by Energias Market Research forecasts that the largest market growth for LiFi will be in Asia, while North America will generate the highest turnover from the technology. Is Europe missing a trick?

H. H.: Indeed, that is a potential danger. You only need to take a look at the example of GSM: Europe laid the foundations for wireless communication with GSM, but the applications that bring in the money were then created elsewhere. The same risk exists for LiFi: Europe is building the infrastructure, although the profits may be skimmed off elsewhere. Be that as it may, I hope that Europe has learned its lesson – that it will simultaneously help to shape the applications to accompany the technology instead of merely helping to develop the infrastructure.

Many of your fellow researchers are of the opinion that fundamental research should be kept separate from commerce. It would seem that you think differently …

H. H.: If you take a look at Stanford or MIT, you won’t see any conflict of interest there either. I find this idea of separation ludicrous. In engineering disciplines, we aim to develop specific concepts which are of use to mankind. That’s how I see myself – and that’s why I have absolutely no problem saying that I’m an applied researcher. For me, that’s an expression of pride. When I undertake research, I also want to see that it has been of use to people at some point.

As a Professor of Mobile Communications, you’re not only occupied with LiFi. What part do other wireless technologies have to play in your research efforts?

H. H.: Our institute is still running a research programme related to wireless technologies. In 2006, for example, we invented spatial modulation – the use of which for 5G is now being trialled by Samsung and Orange. Furthermore, we are conducting research into multi-antenna systems.

Radio continues to be an important element of wireless communication, particularly where long-range communication or extensive coverage are concerned. In this case, trends point towards higher frequency ranges, i.e. 10 GHz and above.

Can you also see potential in the area of personal area networks, or is 5G at the forefront for the time being?

H. H.: I wouldn’t separate the one from the other: 5G definitely also covers personal networks. For example, we also consider LiFi to come under the umbrella of 5G. At any rate, LiFi is standardised in IEEE standard 802.11, which forms part of the 5G initiative. Radio and LiFi technologies complement one another rather than causing interference. Together, they make up the nervous system of the digital society of the future.

Is it even possible for someone like you to step aside and critically examine the full extent of the trend towards ever-increasing networking from a distance?

H. H.: Of course that’s difficult when you’re so completely absorbed in your research. On the plus side, my wife and our four children constantly provide me with a different perspective. Yet when all is said and done, I don’t view the growing significance of networking as a negative point.

Only by doing so can we increase sustainability, solve existing problems and ensure that economic development is distributed more fairly throughout the world. The crux of the matter is to use technology correctly – a factor which is not entirely in the hands of researchers.

Yet overall, technology has definitely improved our quality of life over the years. I’m also excited by the idea of putting these LiFi systems together because I know they’ll contribute to that as well.