Having coined the term, he insists that Li-Fi-enabled LED light bulbs can also transmit data at speeds that are much higher than Wi-Fi (wireless fidelity). In an email interview, Haas talks about the future of the Internet of Things (IoT), impact of 5G, and challenges in securing connected devices. He will also address EmTech India 2017—an emerging tech conference organized by Mint and MIT Technology Review—on 10 March in New Delhi. Edited excerpts:
What inspired you to coin the term Li-Fi? And why did it take over a decade to announce Li-Fi to the world?
Inspiration: 16 years ago, I was responsible for an international research project at Siemens Mobile Networks looking at developing a patent portfolio for 4G which is now LTE (long-term evolution). At that time, I realized that with the paradigm shifting transition from mobile telephony to mobile Internet, the radio spectrum would, at some point, not be sufficient. So, when I joined academia again in 2002, I started to look out for alternative ways to do wireless communications. That was exactly the time—around the year 2000—that high brightness 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 high-speed data communication.
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How does Li-Fi on an LED light bulb work? Does Li-Fi actually need a clear line of sight?
An LED can be controlled to switch on and off very rapidly, so rapidly that to the human eye there is simply a constant light. When ‘on’, this can be equated to a positive signal (in binary terms = 1), when ‘off’, this can be equated to a zero signal (in binary terms = 0). So, there is, therefore, the ability to stream data as a series of ‘0’ and ‘1’ binary signals. Li-Fi does not need a clear line of sight; data streams can be reflected or diffuse. There are applications where line of sight is an element but it is certainly not required for all applications.
Are LEDs a must for Li-Fi? Why can’t Li-Fi work with just any other bulb?
Li-Fi communication can be provided via any source of light that can be controlled to achieve very rapid ‘on/off’ light signals. So, LEDs are one way of doing this. Equally, laser light sources can be used. However, traditional incandescent light bulbs cannot be programmed to achieve this, so they are not suitable for Li-Fi communications.
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You say that as Li-Fi can’t penetrate walls, it has a clear advantage over Wi-Fi in terms of security. But could that also be a disadvantage?
The element of a complete Li-Fi system that delivers data streams (communication) via light is only one part of the whole system. The light data stream will at some point in the complete system be converted into an electronic data stream. This means that while a data stream from, for example, an LED light (the access point) in a room to an individual user computer will be secure with respect to anyone in another room, it is also possible to configure the backhaul components of the system to deliver the same data stream to another access point in any other location. The backhaul components are, for example, the wiring or fibre connections to the LED lighting system. So, in short, the answer to the question is ‘no’. What Li-Fi systems enable one to do is to build in an inherently more secure communication system while maintaining the ability to communicate to any other user in any other location.
Also, the feature that walls block the light results in less interference. Interference reduces data rate. This is why you cannot have two Wi-Fi access points using the same radio frequency channel in close proximity (even if they are in different rooms).
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What speeds have you achieved with Li-Fi? How and why, according to you, does it score over Wi-Fi?
We have shown, with laser diodes, a speed of about 100 gigabits per second (Gbps). We have recently shown 8 Gbps from a single LED which is a world-record. With LEDs that you can buy off the shelf, which are primarily LEDs with a phosphorous coating, you can achieve about 100 megabits per second (Mbps) 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 communications (VLC).
How do you see Li-Fi’s potential in India?
The potential for using Li-Fi in India is simply enormous. Two examples illustrate the point. Connecting rural communities to the internet: Li-Fi technology in conjunction with solar cells as receivers offers solutions that could deliver communications and access to the world wide web in a way that the current free space optical (FSO) systems on their own cannot do. Smart manufacturing: use of Li-Fi to control manufacturing processes has enormous potential for introducing efficiencies into existing manufacturing environments as well as the introduction of new ‘smart LiFi enabled’ robotics and instrumentation. Both of these diverse application areas are ones where Li-Fi can deliver great advances.
What progress have you achieved in commercializing Li-Fi? What is its market potential? How do you see Li-Fi technology enabling the development of IoT?
The Edinburgh spin-out company pureLiFi is successfully commercializing LiFi for certain applications, e.g. small cell communications in buildings; see purelifi.com for more detail. The potential market for Li-Fi solutions is estimated by independent market analysts to be greater than $100 billion by 2022. IoT applications is just one exciting area where Li-Fi has the potential for completely revolutionizing the way we live.