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Researchers, working on Ultra-Parallel Visible Light Communications (UP-VLC) project, have demonstrated 3.5Gpbs free space data transmission via three separate micro-LEDs that emit red, blue and green colours. In effect, combining the three colours (that makes up for white colour), researchers say that achieving data rates over 10Gbps is feasible.
The technology enabler here is called – “Li-Fi”, a term coined by Prof. Harold Haas of University of Edinburgh, uses LED lights as medium of data transmission. Li-Fi, academically referred as “Visible Light Communication”, aims to use existing micro- LED light bulbs for both illumination and communication.
With the advent of this technology, soon you will see all the illuminated spots in offices, houses or any other place turning into internet hotspots streaming high quality data. It has become a hot topic and soon many big corporations will jump on to the Li-Fi bandwagon.
It all started with Prof. Hass’s research group demonstrating the proof-of-concept results that exploited the higher peak-to-average ratio (PAR) property of Orthogonal Frequency Division Multiplexing (OFDM) systems. PAR, otherwise called “Crest Factor”, is a disadvantage in RF communications. The research group have used this property to turn commercially available LED bulbs to ultra-high speed wireless hotspots. Later, this work was featured in TIME magazine’s “50 Best inventions of the year 2011” and Nobel Laureate Prof. Hänsch listed this work in his book titled “100 ground-breaking ideas” that could shape the next century.
Using OFDM, micro-LED light bulbs are enabled to handing millions of light-intensity-changes per second. Essentially, the micro-LED bulbs are switched on and off depending on the input bits –‘0’ or ‘1’. The switching is done at such a high speed that it is undetectable by human eye. Thus both un-flickering-illumination and high-speed-communication are achievable under this condition.
Li-Fi carries the promise of breaking the bandwidth-crunch suffered by existing wireless systems. The demand for more bandwidth is skyrocketing day by day with the proliferation of wireless enabled devices. The crunch faced by Radio-Frequency (RF) systems, is also compounded by complex government regulations, needs of a growing base of customers and risking of the performance issues due to these challenges.
Li-Fi is essentially a wireless system. It uses the visible light region of the electromagnetic spectrum which is 10,000 times larger than the microwave region of the electromagnetic spectrum. This opens up the utilizable frequencies to the order of terahertz level. It will not interfere with existing devices and it can be used in areas where there is extensive RF noise or in places where RF frequencies are restricted (like in airplanes).
Watch the TED talk – “Wireless data from every light bulb”- where Prof Haas demonstrates the capability of Li-Fi technology system prototype (using a desk-lamp) that steams a HD movie in real-time.
