LED lighting to provide internet access at twice the speed of Wi-Fi
LED lighting could provide a source of internet access with wider bandwidth and quicker response times than current Wi-Fi connections, according to research published by the IEEE (Institute of Electrical Engineers). The system, dubbed Li-Fi, could be used to supplement existing Wi-Fi systems or in some cases replace traditional Wi-Fi provision.
One of the researchers, Harald Haas, chair of mobile communications at the University of Edinburgh, said: "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 Oxford University, Cambridge University, St. Andrews University and Strathclyde University, are halfway through a four-year, £5.8 million project funded by the Engineering and Physical Sciences Research Council, in the UK.
The technology they are investigating is called ultra-parallel visible light communication, which would use a range of colours of light to provide high-bandwidth over distances of a few metres.
Members of the research team showed off the first fruits of their progress at the IEEE Photonics Conference last month. 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.
Haas says that this version is only limited by existing LEDs, and by the use of LEDs as transmitters and detectors at the same time. Members of the consortium, however, have created a better LED, which provides a data rate close to 4 gigabits per second operating on just 5 milliwatts of optical output power and using high-bandwidth photodiodes at the receiver.
With a simple lens to enhance the distance, they can send data 10 metres at up to 1.1 Gb/s, and soon they will increase that to 15 Gb/s, Haas says. The 802.11ad Wi-Fi standard for the 60-gigahertz radio band reaches just under 7 Gb/s, so Li-Fi would more than double that rate.
Haas expects LEDs to evolve past just being light sources, much the same way the phone evolved from a communications device to a mobile computer. “In 25 years, every lightbulb in your house will have the processing power of your phone today,” he says. “It will in the future serve illumination as just one of many purposes.”
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