LED lights could become network devices, too

Fraunhofer Institute has demonstrated how conventional LED lighting could be used to send and receive data to laptops or smartphones, with speeds up to 3Gbps.

Fraunhofer's visible light communications (VLC) technology, shown in an artist's conception here, could beam data to laptops and smartphones from conventional LEDs in light fixtures.
Fraunhofer's visible light communications (VLC) technology, shown in an artist's conception here, could beam data to laptops and smartphones from conventional LEDs in light fixtures. Fraunhofer Institute

Today, you've got wireless networks that use radio waves and you've got optical networks that use light traveling in tiny glass fibers. Tomorrow, if Fraunhofer Institute research comes to fruition, a combination of the two could turn living-room lights into network devices.

The German applied-research lab has developed wireless networking that uses rapidly blinking LEDs to transmit data through the air. The technology can send data at speeds up to 1 gigabit per second -- and by using three colors of light, triple that data rate is possible, Fraunhofer said.

The technology could be useful in crowded, interference-prone situations such as trade shows or for sending information from streetlamps to passing cars, the institute believes.

"My personal belief [is that the] first applications will be on the professional level, such as conference rooms, fair trade booths, industrial production environments, and hospitals," said Anagnostis Paraskevopoulos, a researcher with the institute's photonics network group.

The technology could be built into existing room lights with conventional LEDs, Paraskevopoulos added.

There are plenty of caveats. LEDs can use significant battery power, so very short-range communications are better done with infrared lasers, Paraskevopoulos said.

Another issue is that bright sunlight oversaturates the photodiode light receivers, hampering outdoor use. And performance drops with distance; Fraunhofer says it gets about 100Mbps at a distance of 20 meters.

And the visible-light communications requires line-of-sight communications, which is far less convenient than radio communications that work anywhere in a room and often through walls. However, Paraskevopoulos said, a room could have all its LED lights coordinated so a person could sit anywhere within.

Another possible problem crops up with two-directional communications, in which a person's laptop or smartphone could transmit as well as receive. Nobody wants a laptop with a distracting bright LED on top. But in that scenario, an infrared LED could be used that produces light invisible to the human eye, Paraskevopoulos said.

About the author

Stephen Shankland has been a reporter at CNET since 1998 and covers browsers, Web development, digital photography and new technology. In the past he has been CNET's beat reporter for Google, Yahoo, Linux, open-source software, servers and supercomputers. He has a soft spot in his heart for standards groups and I/O interfaces.

 

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