Communication by visible light after the Wi-Fi, Li-Fi

The visible light communication (VLC, Visible light communication) uses light pulses to transmit information remotely. This technology, in other designated Li-Fi, in some cases could become an alternative to Wi-Fi

In his speech at the TED Global Conference 2011 [1], Harald Haas, Professor of Mobile Communications at the University of Edinburgh has shown how to set up a wireless network through LEDs. The principle is simple: to transmit information LEDs, photodiodes receive it. If an LED is lit, it sends a bit 1, if it is off, a bit 0. LEDs can change state very quickly and therefore have sufficient capacity to transmit information. The frequency of the LEDs is so fast that the human eye does not see the flashing and sees a steady light.

The research project D-LIGHT, led by Harald Haas, aims to disseminate the new technology. The ultimate goal being the creation of a university spin-out in 2012 to commercialize LEDs.

Specifically, the current research focuses on improving the flow of VLC. Teams of researchers from the Universities of Oxford and Edinburgh are working on parallel data transmission using LED panels. Other work concerned with the use of LEDs of different colors to use different frequency channels. A team from the Heinrich Hertz Institute in Berlin has recently managed to achieve a throughput of 800 Mbit / s using a white LED. LEDs developed in the project should D-LIGHT on the other hand be able to transmit information to 100 Mbit / s or faster speeds than most current broadband offers.

Once established, the VLC technology could solve the problem of available bandwidth on the radio. In 2009, the Federal Communications Commission of the United States (U.S. Federal Communications Commission) has issued a warning in effect on the reduction of available radio frequencies. Indeed, the transmission of ever larger volumes of data via mobile phones could soon exceed the available capacity of bandwidth across the spectrum of radio waves. VLC technology could be an alternative, especially since the infrastructure is already in place and that the visible light spectrum - the number of available frequencies - is ten thousand times higher than that of radio waves.

According to Harald Hass, there are approximately 14 billion light bulbs used for lighting in the world. Many points where you could install VLC LEDs. He believes that the Li-Fi network would cost ten times cheaper than Wi-Fi Because VLC uses light waves rather electromagnetic, the technology could be used in aircraft or integrated medical devices, even in water, where the Wi-Fi does not work.

But not everyone shares the enthusiasm of Harald Haas. Signal reception can be a problem when the transmitter and receiver are not aligned. An obstacle, the same end, can prevent transmission of the light beam. Sunlight can also be a source of disturbance. Mark Leeson, University of Warwick in the UK, although there are some very good applications behind the VLC, he doubts that this technology can completely replace Wi-Fi

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The project D-LIGHT

D-LIGHT (for Data Light) is a research project of the Institute for Digital Communications (Institute for Digital Communications) from the University of Edinburgh, over two years and funded by the Engineering and Physical Sciences Research Council ( EPSRC Research Council for Engineering and Physical Sciences). After the first year of work, the team of D-LIGHT was able to design a prototype LED able to disseminate information to 100 Mbit / s. The LEDs will be developed to replace conventional lighting. Eventually, many applications are considered: replacement of Wi-Fi in homes, Internet access via the public lighting in aircraft, aircraft equipment in hospitals, submarine communication ...

[1] TED Global 2011: http://conferences.ted.com/TEDGloba ...

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Sources:
Speech by Harald Haas at TED: http://bit.ly/oTVugn
New Scientist: http://redirectix.bulletins-electro ...
Project D-LIGHT: http://visiblelightcomm.com/

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Author: Peter Chrzanowski

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