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