Abstract :
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.
Download :