Wireless data may eventually be delivered by LED light

Think about it: light fixtures are everywhere, and each one is capable of serving as a data transmission device. A leading proponent calls it 'Li-Fi.'
Written by Joe McKendrick, Contributing Writer on

One IT visionary says we could make data accessible anywhere in the world -- with no additional cost for infrastructure. Turn existing light fixtures -- from street lamps to smartphone LED screens -- into rapidly pulsating data transmitters.

Harald Haas, a professor of engineering at Edinburgh University, even has a name for this new networking technology: "Li-Fi," for light-fidelity. At a recent TED conference, Haas pitched his proposal for Li-Fi data transmission, suggesting that the applications and capacity for data would be limitless -- from using car headlights to transmit data, or employing line of sight light sources as data transmitters.

Haas says data can be transmitted via LED bulbs that glow and darken faster than the human eye can see. Plus, an LED is a semiconductor itself, and therefore programmable.

The system, which he's calling D-Light, uses a mathematical trick called OFDM (orthogonal frequency division multiplexing), which allows it to vary the intensity of the LED's output at a very fast rate, invisible to the human eye. For the eye, the bulb would simply be on and providing light. The signal can be picked up by simple receivers. As of now, Haas is reporting data rates of up to 10 MBit/s per second (faster than a typical broadband connection), and 100 MBit/s by the end of this year and possibly up to 1 GB in the future.

There's plenty of capacity, he says: "We have 10,000 times more spectrum, 10,000 times more LEDs installed already in the infrastructure. You would agree with me, hopefully, there's no issue of capacity anymore." The added bonus, he adds, is that the infrastructure is free, and even would promote more rapid adoption of more energy-efficient LED bulbs. "It should be so cheap that it’s everywhere," Haas says. "Using the visible light spectrum, which comes for free, you can piggy-back existing wireless services on the back of lighting equipment."

The alternative is to keep building tranmission towers, he says, noting that "radio waves are scarce, they're expensive, and we only have a certain range of it," he says.

Plus, there would be wireless access points anywhere there is a light source. Even smartphones, with their LED displays, could serve as data sources. Consider all the possibilities, Haas elaborates:

"...In hospitals, for new medical instruments; in streets for traffic control. Cars have LED-based headlights, LED-based back lights, and cars can communicate with each other and prevent accidents in the way that they exchange information. Traffic lights can communicate to the car and so on. And then you have these millions of street lamps deployed around the world. And every street lamp would be a free access point."

Security is another benefit, he points out, since light doesn't penetrate through walls, he points out:

"You would agree with me that light doesn't penetrate through walls. So no one, if I have a light here, if I have secure data, no one on the other side of this room through that wall would be able to read that data. And there's only data where there is light. So if I don't want that receiver to receive the data, then what I could do, turn it away. So the data goes in that direction, not there anymore. Now we can in fact see where the data is going to."

(Cross-posted at SmartPlanet Business Brains.)

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