IEEE Spectrum, 20 November 2014

Visible light communications could outshine Wi-Fi in industrial settings

Light fantastic:  A CMOS digital-to-analog converter developed at the University of Edinburgh helps LEDs act as communications devices.

As LEDs become a more common source for room lighting they’re opening a new pathway for linking mobile devices to the Internet, with the potential for wider bandwidth and quicker response time than Wi-Fi. At least that’s what researchers such as Harald Haas, chair of mobile communications at the University of Edinburgh, are hoping.

"All the components, all the mechanisms exist already," Haas says. "You just have to put them together and make them work."

Haas’s group, along with researchers from the Universities of ­Cambridge, Oxford, St. Andrews, and Strathclyde, are halfway through a four-year, £5.8 million project funded by the Engineering and Physical Sciences Research Council, in the United Kingdom. They are pursuing ultra­parallel visible light communication, which would use multiple colors of light to provide high-bandwidth linkages over distances of a few meters. Such a Li-Fi system, as it’s been dubbed, could supplement or in some instances replace traditional radio-based Wi-Fi, they say. But taking on such a broadly used radio technology is an uphill battle.

At the IEEE Photonics Conference in October, members of the consortium showed off the progress they’re making. For instance, the team has used commercially available red, green, and blue LEDs as both emitters and as photodiodes to detect light. By doing that, they created a system that could both send and receive data at aggregate rates of 110 megabits per second. When transmitting in one direction only, they reached a rate of 155 Mb/s.

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