27-08-2016, 04:29 PM
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Abstract:
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 have 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. One germen phycist.Harald Haas has come up with a
solution he calls “data through illumination” –taking the fibber
out of fiber optic by sending data through an LED light bulb
that varies in intensity faster than the human eye can follow.
It’s the same idea band behind infrared remote controls but far
more powerful. Haas says his invention, which he calls DLIGHT,
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,
smart phones, and tablets is transmitted through the light in a
room. And security would be snap – if you can’t see the light,
you can’t access the data.
Keywords: LED (Light emitted diode), Wi-Fi, VLC
INTRODUCTION
LiFi is transmission of data through illumination by taking the
fiber out of fiber optics by sending data through a LED light
bulb that varies in intensity faster than the human eye can
follow.Li-Fi is the term some have used to label the fast and
cheap wireless-communication system, which is the optical
version of Wi-Fi. The term was first used in this context by
Harald Haas in his TED Global talk on Visible Light
Communication. “At the heart of this technology is a new
generation of high brightness light-emitting diodes”, says
Harald Haas from the University of Edinburgh, UK,”Very
simply, if the LED is on, you transmit a digital 1, if it’s off
you transmit a 0,”Haas says, “They can be switched on and off
very quickly, which gives nice opportunities for transmitted
data.”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 eye cannot notice, so the output appears constant.
More sophisticated techniques could dramatically increase
VLC data rate. Terms at the University of Oxford and the
University of Edingburgh are focusing on parallel data
transmission using array of LEDs, where each LED transmits
a different data stream. Other group are using mixtures of red,
green and blue LEDs to alter the light frequency encoding a
different data channel.Li-Fi, as it has been dubbed, has already achieved blisteringly high speed 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. The technology was demonstrated at the
2012 Consumer Electronics Show in Las Vegas using a pair of
Casio smart phones to exchange data using light of varying
intensity given off from their screens, detectable at a distance
of up to ten metres.
4.3 Smarter Power Plants
Wi-Fi and many other radiation types are bad for sensitive
areas. Like those surrounding power plants. But power plants
need fast, inter-connected data systems to monitor things like
demand, grid integrity and (in nuclear plants) core
temperature. The savings from proper monitoring at a single
power plant can add up to hundreds of thousands of dollars.
Li-Fi could offer safe, abundant connectivity for all areas of
these sensitive locations. Not only would this save money
related to currently implemented solutions, but the draw on a
power plant’s own reserves could be lessened if they haven’t
yet converted to LED lighting
4.4 Undersea Awesomeness
Underwater ROVs, those favourite toys of treasure seekers
and James Cameron, operate from large cables that supply
their power and allow them to receive signals from their pilots
above. ROVs work great, except when the tether isn’t long
enough to explore an area, or when it gets stuck on something.
If their wires were cut and replaced with light — say from a
submerged, high-powered lamp — then they would be much
freer to explore. They could also use their headlamps to
communicate with each other, processing data autonomously
and referring findings periodically back to the surface, all the
while obtaining their next batch of orders.