If you were impressed with the technological advances in LED laid out in our LED blog article of June last year, the latest functionality of these versatile semi-conductors will blow your mind — and will certainly brighten your journey home through the darkening winter evening, as you dart out of the rain and try to attach your smart gadgets to capricious radio frequency (RF) hotspots to fire off an email to your boss with urgent corrections to the report she’ll no doubt already be reading on the train home…
To recap, Light Emitting Diodes - LEDs - are now able to provide light that is more energy efficient, cheap, long-lasting, bright and many times less resource-intensive and greenhouse gas-emitting than either traditional incandescent or low-energy compact fluorescent forms of artifical light.
Research funded by the EPSRC (Engineering and Physical Sciences Research Council) is investigating the potential for LEDs to become more than a way to throw out light, but to double-up as a super-fast multi-channel highway of data through Visible Light Communication (VLC), and hence the future replacement for WiFi.
The premise behind commercial scale VLC is that because lighting is pretty much ubiquitous, communications can ride along almost for free. The LiFi Consortium, an industry think-tank promoting the commercial development of optical wireless communications (OWC) technology, say: ‘Think of a TV remote in every LED light bulb and you’ll soon realise the possibilities of this technology’.
To get online, most of us have long-since ditched the wires and now hook up to the internet through home wireless networks and via whatever local WiFi signal is available — or 3 or 4 G mobile broadband signals — as we work and play — and communicate — on the move. The most pressing problem with WiFi is that the available radio spectrum is limited, and experts predict will be saturated by the end of 2020. Another limitation is one that you may have encountered when each member of your household is streaming data ~ like music libraries, video games and HDTV movies ~ to their smart devices — WiFi speeds of 50 to 100 megabits per second (Mbps)are simply not fast enough to efficiently transmit large data files.
Visible light is part of the electromagnetic spectrum and 10,000 times broader than the radio spectrum, affording potentially unlimited capacity. Existing LED light bulbs could be converted to transmit LiFi signals with a single microchip and span an entire home or office, making timing-out and signal interference typical of radio wave wireless networking a thing of the past - and vastly increasing the speed of data transmission.
LiFi signals work by rapidly switching bulbs on and off – too quickly to be noticed by the human eye. The recent breakthrough builds upon this by using tiny micro-LED bulbs to stream several lines of data in parallel across the red, blue and green visible light spectrums. Allthough LiFi bulbs would have to be kept on to transmit data, were light not required for periods of time the bulbs could be dimmed to the point that they were not visible to humans and yet still functional.
Radio frequency communication requires radio circuits, antennae and complex receivers, whereas LiFi is much simpler and uses direct modulation methods similar to those used in low-cost infra-red communications devices such as remote control units (but which are limited due to eye safety).
One draw-back of LiFi is that the data receiver would have to be within ‘sight’ of the transmitter-bulb, since visible light does not penetrate solid materials.
But in other ways this could be a huge draw - cyber insecurity is currently a critical issue, partly because WiFi transmissions containing sensitive data automatically penetrate solid walls, leaving them vulnerable to unauthorised access or attack. With LiFi, what you get is what you see, or to put it another way, what you see is what you send, so if you’re not within sight of a LiFi network, you can’t connect to it, making it an attractive proposition for financial and political data systems networks, and potentially for the future of cashless payment systems. WiFi is open, general-purpose broadband; LiFi is secure, special-purpose narrowband - almost made for cyber finance.
Another plus of LiFi is that the technology would also be of use in situations where radio frequencies cannot be used for fear of interfering with electronic circuitry. In fact, the systems are already being used in such places as hospitals and airports and even on board aircraft.
So - how far are the researchers away from turning this technology into something we will see on every street corner - literally?
The EPSRC-funded research is a cross-specialist venture, the Ultra Parallel Visible Light Communications project, which will complete its investigations in September 2016. One of its chief researchers, Professor Haas of Edinburgh University (who first coined the term ‘LiFi’), has set up his own company PureVLC to push forward the commercial production of LED LiFi units.
The research specifically aims to combine lighting functions with optical communications providing new forms of spatial multiplexing using high-density arrays of unique gallium nitride (GaN) LEDs. The speed of the systems is paramount and test LiFi waves so far have been
mostly ‘only’ 150 Mbps (megabits per second)
at least twice that of the everyday 802.11n WiFi in many homes and offices
less than half the 400Mbps available through one of the new 802.11ac wireless WiFi networks possible with powerful routers and receiving devices
more recently already able to reach 3.5 Gbps (gigabits per second) across red, green and blue visible light frequencies in parallel - this means that over 10 Gbps is possible
Green Element finds that one of the biggest attractions of LiFi is the energy saving credentials of LED technology:
19% of global electricity is used for lighting
30 billion light bulbs are in use worldwide
1 billion barrels of oil per year could be save by replacing all these light bulbs with LEDs
smart-sensoring integrated into LED low-energy bulbs is incomparably ‘kind’ to the environment
If LEDs are manufactured to incorporate wireless data communication within each unit, then that could be a powerful driver for replacing old-style bulbs with these highly energy-efficient alternatives. And the possibilities for the future are as broad as the visible light spectrum:
The prototype of a mobile phone with an incorporated VLC system was presented by Casio at the Consumer Electronics Show in Las Vegas in January this year. In the coming years, both the industrial and consumer markets will see the arrival of more exciting Li-Fi products….
You sit back in your smart car humming along to a new-release hit while the street lights keep you abreast of traffic and weather updates and guide your vehicle along the quickest route home… your phone picks up a voice call and it’s automatically turned into a 3D rendition of your loved-one floating in the space beside you as they’re holding up a bargain reco (recovered material) designer jacket they think you ought to try on — so your image joins his in the 3D space, wearing the jacket, turning and twirling while the technology matches your orientation and body gestures for a ‘digital fitting.’ Later, the two of you step out of your LiFi-lit CMOS-controlled programmable eco-environment home, to join your friends in watching a brand new release in a shared GigaSpot hotspot for instant 3D digital movie ‘airings’— and yes, you are already wearing that exquisitely-tailored, snug-fitting reco-jacket…
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