Li-Fi: Edinburgh prof seeds LEDs forcommunication6 October 2012, by Nancy Owano

Credit: pureVLC Ltd

(Phys.org)—"We believe wireless communicationsshould be as reliable as lighting." That is acompany motto of startup PureVLC (Visible LightCommunication), which aims to connect thetwo—communications and light. They have anapproach that could be an alternative toradiofrequency spectrum, as there are worriesabout "running out of gas" because demand growsfor space. "We talk about the Internet of Thingswhere every device is interconnected, but withoutmore bandwidth it will be impossible to providereliable communications to all of these 'things,'"say company sources.

PureVLC has in mind an alternativecommunications path that could hit 1Gbps wirelessspeeds. Harald Haas, the company CTO, has saidhis company is relying on the potential of the useof LEDs for transmitting wireless data, Rather thancomplex radio schemes at increasingly higherfrequencies, "the performance of VLC looks veryfavorable," said the company. PureVLC intends tocommercialize LED systems. The team hopes thetechnology can be integrated into mobile devices.

Haas is professor of mobile communications at the

University of Edinburgh. His team have developedtheir wireless networking system to handle datatransfer using light instead of radio waves. Theyhave been able to transmit and download streamedvideo using the visible light method, according to a Professional Engineering report published earlierthis week. The report looks at this work so far.

The approach is called "Li-Fi," where LEDs areused to transmit data to photo-sensor receivers bymaking changes in the intensity of light so fast theeye cannot see. The pattern of this flashing lightcan project the data in the form of 0s and 1s at veryhigh speeds. The data is encoded in the light andtransmitted from the light source. He commentedthat it is not really a case of switching the light onand off but of changing the intensity in a subtle andspecific way.

Haas also told Professional Engineering that thecompany was developing a smart lightingdevelopment kit (SLDK) that can enable lightingsystems that are already in place to transmit andreceive data, reaching network speeds of up to 50megabits per second. (The SLDK will be capable ofdownloading and uploading data at speeds ofbetween 15 and 50Mb/s.)

According to the company, the SLDK will enablelighting manufacturers to add "visible lightcommunications" to their products. The kit isdesigned to enable rapid implementation of VLCtechnology using standard lighting fixtures.

Haas last year performed the first publicdemonstration of visible light communications liveat TED Global, where he showed an angle poiselamp fitted with an LED bulb transmitting highdefinition video displayed onto a massive screen.When he interrupted the light with his hand thevideo froze and it was then restored when heremoved his hand.

More information: purevlc.com/

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