That theory about LED lightbulbs transmitting data? It's true. Li-Fi is here.

Yes, multiple tests have shown that LED lighting fixtures can transmit wireless data at very competitive high speeds. A commercial product started shipping several months ago.

What if every light bulb in the world could also transmit data?

In July 2011, Harald Haas, a professor of engineering at Edinburgh University,  poised that rhetorical question to a TED Global audience.

Then he went on to answer it. Broadband would be plentiful, nearly as limitless as oxygen itself, as it flowed from a standard-off-the-shelf LED (light-emitting diode). Society would come to view the way we transmit data now, which is via electromagnetic waves — specifically, radio waves — as quaint, at least when we were not scoffing in memory at its costs and frequency limitations.

Haas wasn't dabbling in science fiction. His theory was that the data could be transmitted via the visible light spectrum, or VLS. Like radio waves, VLS is part of the electromagnetic spectrum, but it is the "good" part, Haas explained to the audience. It's not like gamma rays, which can be dangerous, or ultraviolet light, which are also unsafe. Infrared can possibly be harnessed, but again at low levels for safety reasons.

The visible light spectrum though, sandwiched in the middle, is inherently safe to use, he said.

Before I describe Haas' theory and subsequent developments in detail, I would like to jump ahead in this story now to tell you that broadband transmission via the visible light spectrum — which is also called Li-Fi — is here, and there are multiple practical use cases for the technology.

Actually the theory of VLS has been here for quite a while, but it is posed to be here in a big way, now that the National Aeronautics and Space Administration (NASA) is working with it.

At the start of the month, NASA announced it had signed a Space Act agreement with the CEO and Chairman of Light Visually Transceiving (LVX) System Corp., John Pederson, to license researchers at the Kennedy Space Center to develop visual light communications applications.

NASA's interest is to use Li-Fi to supplement the International Space Station's Wi-Fi system, and possibly enhance it with such features as Global Positioning Satellite Routing Systems architecture.

"A future manned spacecraft making a trip to Mars could be a candidate for this kind of communications system," says principal investigator and research physicist Eirik Holbert. "Also, a deep-space habitat operating on the surface of the planet could use VLC."

But Li-Fi is also suited for more humble use cases such as providing broadband in a coffee shop or company headquarters.

Any building with LED light fixtures could be set up to use VLC technology, Holbert said. LEDs in lighting fixtures communicate by flashing or blinking too fast for the human eye to discern.

"The prototype light fixtures we've developed are primarily made with readily available off-the-shelf hardware," he said. "We've been able to build simple prototype receiver hardware from $5 worth of parts."

It can connect to the Internet through any usual manner, such as a receiver/transmitter device connected to a laptop computer or cellular telephone using a USB (universal serial bus) port, he said.

Li-Flame ships

That is pretty much how Haas described it as well in his speech. Not that he has much right to feel aggrieved by the NASA project — there are, in fact, a number of research initiatives around the world exploring Li-Fi. The first scientist to identify the phenomenon, according to NASA, was Alexander Graham Bell, inventor of the telephone, and less famously, the photophone. In a demonstration in Washington, D.C., in the 1880s, Bell transmitted speech using modulated sunlight over a distance of several hundred yards.

But Haas can be credited with coining the term "Li-Fi" and advancing the vision of using VLC technology to deliver high-speed, bidirectional, networked and mobile wireless communications similar. He went on to launch a commercial venture called pureLiFi,  also in Edinburgh, which shipped its first fully wireless optical networking systems in the fourth quarter of 2014. The product, Li-Flame, turns standard LED fixtures into wireless Internet access points. Just like the theory said it would.

pureLiFi demoed it a few months later at the Mobile World Congress in Barcelona.

Competitive high-speed performance

The Berlin-based Fraunhofer Heinrich Hertz Institute is working on the technology and applications as well. This May it used VLC technology to implement an optical broadband system at at facility at Lake Constance in Germany to replace the existing radio-based Wi-Fi solution. The project is taking place over several stages, but already the institute seems confident of the system's performance.

Indeed, performance has proved to be quite competitive with other high-speed broadband sources throughout all the use cases, and the FHHI test was no different.  The institute reported that data rates of one gigabit per second and more were achieved with conventional LEDs, a rate that allows for the "flawless" transmission of video data in HD and 4K quality.

The insights from the tests so far, said Fraunhofer HHI project manager Dr. Anagnostis Paraskevopoulos "can lead to user-oriented optimization of the system parameters as well as to accelerated preliminary development efforts.

"In this way, time-to-the-market for respective innovative products in conjunction with potential industry partners, for example in the lighting industry, will be significantly reduced," he said.

Researchers at Disney appear to be less timid about extrapolating conclusions about Li-Fi and its potential uses. Last week Disney Research's wireless research group submitted a paper at a workshop at MobiCom 2015, held in Paris, France, that among other things posited how Li-Fi could help fuel IoT. 

IoT and Magic Princess Dresses

First the paper addressed the (by now) formality of the theory:  LED light bulbs installed in a room can communicate with each other.  But it also goes on to say that LED light bulbs can also communicate with other VLC devices.

This paper explored how the Internet Protocol stack and other networking protocols can be hosted on Linux-based VLC devices and concluded that  the IP stack and the proposed VLC protocols are flexible enough to interoperate.

In case you are wondering why Disney is interested, I've got three words for you: magic princess dress.

As Disney researchers also note, VLC is also a great application for toys.

The magic princess dress, for example, comes with a wand that triggers light effects on a princess dress.

There are LEDs are embedded into the dress and when the child points the wand at the dress, it comes to life at exactly that location. Told you there were practical applications for Li-Fi in the works.

Copyright © 2015 IDG Communications, Inc.

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