Whether you’re using wireless internet in a
coffee shop, stealing it from the guy next door, or competing for bandwidth at
a conference, you’ve probably gotten frustrated at the slow speeds you face
when more than one device is tapped into the network. As more and more people
and their many devices access wireless internet, clogged airwaves are going to
make it increasingly difficult to latch onto a reliable signal. But radio waves
are just one part of the spectrum that can carry our data. What if we could use
other waves to surf the internet?
One
German physicist,DR. Harald Haas, has come up with a solution he calls “Data
Through Illumination”—taking the fiber out of fiber optics by sending data
through an LED light bulb that varies in intensity faster than the human eye
can follow. It’s the same idea behind infrared remote controls, but far more
powerful. Haas says his invention, which he calls D-Light, can produce data
rates faster than 10 megabits per second, which is speedier than your average
broadband connection. He envisions a future where data for laptops,
smartphones, and tablets is transmitted through the light in a room. And
security would be a snap—if you can’t see the light, you can’t access the data.
Li-Fi
is a VLC, visible light communication, technology developed by a team of
scientists including Dr Gordon Povey, Prof. Harald Haas and Dr Mostafa Afgani
at the University of Edinburgh. The term Li-Fi was coined by Prof. Haas when he
amazed people by streaming high-definition video from a standard LED lamp, at
TED Global in July 2011. Li-Fi is now part of the Visible Light Communications
(VLC) PAN IEEE 802.15.7 standard.
“Li-Fi
is typically implemented using White LED light bulbs. These devices are
normally used for illumination by applying a constant current through the LED.
However, by fast and subtle variations of the current, the optical output can
be made to vary at extremely high speeds. Unseen by the human eye, this
variation is used to carry high-speed data,” says
Dr Povey, , Product Manager of the University of Edinburgh's Li-Fi Program ‘D-Light Project’.
In
simple terms, Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses
light instead of radio waves to transmit information. And instead of Wi-Fi
modems, Li-Fi would use transceiver-fitted LED lamps that can light a room as
well as transmit and receive information. Since simple light bulbs are used,
there can technically be any number of access points.
This
technology uses a part of the electromagnetic spectrum that is still not
greatly utilized- The Visible Spectrum. Light is in fact very much part of our
lives for millions and millions of years and does not have any major ill
effect. Moreover there is 10,000 times more space available in this spectrum
and just counting on the bulbs in use, it also multiplies to 10,000 times more
availability as an infrastructure, globally.
It
is possible to encode data in the light by varying the rate at which the LEDs
flicker on and off to give different strings of 1s and 0s. The LED intensity is
modulated so rapidly that human eyes cannot notice, so the output appears
constant.
More
sophisticated techniques could dramatically increase VLC data rates. Teams at
the University of Oxford and the University of Edinburgh are focusing on
parallel data transmission using arrays of LEDs, where each LED transmits a
different data stream. Other groups are using mixtures of red, green and blue
LEDs to alter the light's frequency, with each frequency encoding a different
data channel.
Li-Fi,
as it has been dubbed, has already achieved blisteringly high speeds in the
lab. Researchers at the Heinrich Hertz Institute in Berlin, Germany, have
reached data rates of over 500 megabytes per second using a standard
white-light LED. Haas has set up a spin-off firm to sell a consumer VLC
transmitter that is due for launch next year. It is capable of transmitting
data at 100 MB/s - faster than most UK broadband connections.
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