The expert in wireless communications on why Li-Fi scores over Wi-Fi and how he hopes to make the technology ubiquitous with Li-Fi-enabled LED bulbs, dongles and solar panels
Mumbai: Harald Haas, co-founder and interim chief executive officer of pureLifi, a spin-out from the University of Edinburgh, is on a mission to convince the world that a Li-Fi (light fidelity)-enabled LED light bulb can also transmit data at speeds that are much higher than Wi-Fi (wireless fidelity).
Haas, who coined the term Li-Fi, said in a phone interview that he is also talking to the Indian government to demonstrate how Li-Fi solar panels, too, can receive data, act as a broadband receiver, and help solve rural connectivity issues. Li-Fi appears to be gaining acceptance in the industry and, according to unconfirmed reports, even Apple Inc. is looking at embedding Li-Fi in its future versions of the smartphone.
Haas, who is also a world renowned expert in wireless communications and holds the Chair of Mobile Communications at the University of Edinburgh, also explained why he believes Li-Fi scores over Wi-Fi and how he hopes to make the technology ubiquitous with Li-Fi-enabled LED bulbs, dongles and solar panels. Edited excerpts:
What was the trigger for Li-Fi?
I was doing my PhD research project at Siemens Mobile Networks, where we tried to develop a patent portfolio for GE (General Electric) and at that time, I realized that with the growing demand for data, the radio spectrum would, at some point, not be sufficient. So we started looking out for alternative ways to do wireless communications. That was exactly the time—around the year 2000—that white LEDs (light emitting diodes) were introduced as a mass market device. I realized at that time that light spectrum is part of the electromagnetic spectrum and radio spectrum—part of the same family—and I wanted to explore whether we could use light for data communication.
In particular, we were looking at LED lights and started a research project in the university, where we tried a few ways to increase data rates. How do we communicate at a very high speed with an off-the-shelf LED? That is something we solved and demonstrated at the TED Global Talks in 2011.
But why did it take over a decade to announce Li-Fi to the world?
We needed to figure out ways to test the transmission speed. There were technical hurdles. For example, LEDs have been optimized to provide more lumens per watt and not for high speed communication or bits per watt. This required a lot of research to solve. Besides, I never began my research with the intention of making it big. It was just simple curiosity to explore whether we could transmit one megabit (1 MB) with an LED. When we achieved that, we thought: Why not 10 MB? And we did this, too; we became more ambitious, setting the target at 100 MB. That was around 2011 when we had the technology to do real-time video streaming with an LED lamp. After the TED talk, things went viral since people realized the potential of the technology.
Are LEDs a must for Li-FI? Why can’t Li-Fi work with just any other bulb?
The fact is that an incandescent bulb is basically a piece of wire that is heated up and just 2% is converted into illumination or light. An LED is an electronic device—a semiconductor—that produces light via a process where we have a recombination of electrons with an electron hole in the device, and a photon is emitted.
That is why we can change the intensity of an LED light much faster than we can in an incandescent light bulb. In the latter’s case, you will need to heat it up first so that it can release enough (energy in the form of) photons and wait, then, until it cools down. Such is not the case with LED bulbs. You can switch it on extremely fast and can also modulate data at great speeds on it.
So, how does Li-Fi on LED light bulb work?
Think of it this way. The digital world is made up of bits—1s and 0s. Now you want to transmit these bits using an LED light bulb. The simplest way to do it is to switch on the LED when you want to transmit a 1 and switch it off when you want to transmit a 0. Thus, you can switch this on and off rapidly which are undetectable by the naked eye, while the 1s and 0s are transmitted—in principle. Obviously, given the advancement in technology, there is no switching on and off that takes place.
But does Li-Fi actually need a clear line of sight?
This is the greatest misconception that I’m guilty of because I interrupted the light beam which stopped the video at the TED Global Talk in 2011. However, in the real world, there will be reflections from walls, the floor, even a window and other objects onto the receiver.
With the advanced technology that we have, we can use the reflections as well to transmit data. In other words, we can also communicate through an obstructed receiver that is not in direct line of sight of the transmitter as long as there is enough reflected light coming in.
You say that as Li-Fi can’t penetrate walls, it has a clear advantage over Wi-Fi in terms of security. But that could also be a disadvantage?
True. But we use it as an advantage because data cannot leak into the adjoining room and, thus, prevents eavesdropping. The other advantage is that since it does not penetrate walls, the same light and the same spectrum can be used without interference in communication. The challenges are now more in the way of convincing the masses that Li-Fi is a true wireless communications technology—I call it a 5G technology that can enhance the data rate.
What speeds have you achieved with Li-Fi?
We have shown, with specific LEDs, a speed of about 100 gigabits (GB) per second. With LEDs that you can buy off the shelf, which are primarily LEDs with a phosphorous coating, you can achieve about 100 MB per second from a single LED bulb. What is important is what the user gets from that transmission.
This means that even if you have a Wi-Fi router in your room, you may have to share it with other users, which would mean you have to divide the bandwidth equally. That is not the case with LED light bulbs because we have so many such bulbs in our homes and offices and so on.
By definition, Li-Fi is networked bi-directional communication. It is an additional layer of wireless networking within the heterogenous group of radio networks. It allows mobility, handover and multiple user access—features that make it different from visible light spectrum.
But you also need a microchip to make the LED transmit data...
This is what our company, Pure Li Fi, is doing. We are creating a microchip that you would add to the existing electronics of an LED lamp. You can, hence, buy a Li-Fi enabled lamp.
There are two ways you can approach this: Our technology can work with any LED light bulb. At the moment, we have a box that connects with a bulb. So you could buy our Li-Fi access point and connect to your LED light bulb and turn it into a high-speed device.
The other option is to buy an LED lamp with an embedded Li-Fi chip. You will, of course, need a data connection (similar to how Wi-Fi works with the help of a router) through, say, an Ethernet cable that goes to your lamp which powers it and gets the data to it.
How many pilots have been done to date?
Our firm has engaged in a number of pilots where we have provided a proof of concept and now we are engaging with the lighting industry to have Li-Fi enabled LEDs in buildings and offices.
What is the cost of a Li-Fi enabled light bulb?
That’s a question I can’t really fully answer because we are dealing with early-stage prototypes. The cost will be dependent on the volumes we are able to get. At the Mobile World Congress, we will show the world’s first Li-Fi dongle which will be the size of three-quarters of a credit card. Wi-Fi has a widespread deployment, so the costs are low.
How do you see Li-Fi’s potential in a country like India?
We have also worked on the receiver side which will help a user to get an off-the-shelf solar panel that can be used not only as an energy-harvesting device but also as a data receiver of Li-Fi signals. That opens up big doors for rural communities to provide data connectivity via solar panels. I see this as a way to help Digital India.
Have you spoken to the government?
Yes. We have spoken with the Indian government on these aspects.
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