fiber out of fiber optics by sending data through a LED light
bulb that varies in intensity faster than the human eye can
follow.LiFi is the term some have used to label the fast and
cheap wireless communication system, which is the optical
version of WiFi. 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 tra
nsmitted 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
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.
Li-Fi enviorment
In October 2011 a number of companies and industry groups
formed the Li-Fi Consortium, to promote high-speed opticalwireless systems
and to overcome the limited amount of radio-based wireless spectrum available by exploiting a completely
different part of the electromagnetic spectrum. The consortium
believes it is possible to achieve more than 10 Gbps,
theoretically allowing a high-definition film to be downloadedin 30 seconds.
WORKING TECHNOLOGY
WORKING TECHNOLOGY
This brilliant idea was first showcased by Harald Haas from
University of Edinburgh, UK, in his TED Global talk on VLC.
He explained,” Very simple, if the LED is on, you transmit adigital 1, if it’s off you transmit a 0. The LEDs can be switched on and off very quickly, which gives nice
opportunities for transmitting data.” So what you require at all
are some LEDs and a controller that code data into those
LEDs. We have to just vary the rateat which the LED’s
flicker depending upon the data we want to encode. Further
enhancements can be made in this method, like using an array
of LEDs for parallel data transmission, or using mixtures of
red, green and blue LEDs to alter the light’s frequency
with each frequency encoding a different data channel. Such
advancements promise a theoretical speed of 10 Gbps
–meaning you can download a full high-definition film in just
30 seconds. Simply awesome! But blazingly fast data rates
and depleting bandwidths worldwide are not the only reasons
that give this technology an upper hand. Since Li-Fi uses just the light, it can be used safely in aircrafts and hospitals that are
prone to interference from radio waves.
This can even work
underwater where Wi-Fi fails completely, thereby throwing
open endless opportunities for military operations.Imagine only needing to hover under a street lamp to get
public internet access, or downloading a movie from the lamp
on your desk. There's a new technology on the block which could, quite literally as well as metaphorically, 'throw light on'
how to meet the ever-increasing demand for high-speed wireless connectivity. Radio waves are replaced by light
waves in a new method of data transmission which is being
called Li-Fi.Light-emitting diodes can be switched on and off
faster than the human eye can detect, causing the light source
to appear to be on continuously. A flickering light can be
incredibly annoying, but has turned out to have its upside,
being precisely what makes it possible to use light for wireless
data transmission. Light-emitting diodes (commonly referred
to as LEDs and found in traffic and street lights, car brake
lights, remote control units and countless other applications)
can be switched on and off faster than the human eye can detect, causing the light source to appear to be on
continuously, even though it is in fact 'flickering'.
This invisible on-off activity enables a kind of data transmission
using binary codes: switching on an LED is a logical '1',
switching it off is a logical '0'. Information can therefore be
encoded in the light by varying the rate at which the LEDs
flicker on and off to give different strings of 1s and 0s. This
method of using rapid pulses of light to transmit information
wirelesslyis technically referred to as Visible Light
Communication (VLC), though it’s potential to compete with
conventional Wi-Fi has inspired the popular characterisation Li-Fi.
