Forget Wi-Fi, boffins get 150Mbps Li-Fi connection from a lightbulb

Many (Chinese) hands make light work

Scientists in China are reporting great success in replacing traditional Wi-Fi radio traffic with Li-Fi, a system that uses the light signals from an LED lightbulb to provide a line-of-sight data stream.

Li-Fi, or light fidelity, was developed by Professor Harald Haas at the University of Edinburgh, who was disenchanted with radio as a data transmission tool. Using light instead of radio opens up 10,000 times more available spectrum than radio – and it's highly energy efficient compared to radio towers that use most of their power for cooling and only five per cent for data transmission.

Haas developed a digital signal processing system to modulate the output of an LED lightbulb, at a rate faster than the human brain can detect, to send data signals. He managed about 10Mbps transfer speeds, British boffins have done better, but the Shanghai Institute of Technical Physics has now designed new hardware that uses Li-Fi for high-speed data which are almost ready for market.

Now the Middle Kingdom light-masters used a single one-watt LED lightbulb with a signal modulation chip to send data to four PCs at 150Mbps. The team used specially designed signal modulators and a receiving station to achieve these speeds, but say the potential of the system could allow much higher rates of data transfer.

"Wherever there is an LED lightbulb, there is an Internet signal," Chi Nan, an information technology professor with Shanghai's Fudan University told Xinhua. "Turn off the light and there is no signal. If the light is blocked, then the signal will be cut off."

That said, the level of light in the LED bulb can be dimmed to near darkness and still be capable of transmitting data. There's also a side benefit, in that light can't penetrate walls, which is more secure than radio that can be slurped in a drive-by hacking.

Chi said that while the system was not yet ready for mass production, Chinese manufacturers will be demonstrating 10 Li-Fi kits at next month's China International Industry Fair.

Looking further forward it may even be possible to build receiver technology into smartphone cameras to pick up the data from the light and its LED flash to transmit. Haas has also suggested that car headlights could be used for vehicle-to-vehicle data transmission.

"In the future you will not only have 14 billion (LED) lightbulbs, you may also have 14 billion Li-Fi's deployed worldwide for a cleaner, greener, and even brighter future," Haas said at the TED talk introducing the technology. ®

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