Li-Fi The Optical Version Of Wi-Fi

Li-Fi The Optical Version Of Wi-Fi

LiFi (LightFidelity) is a fast and cheap optical version of WiFi, the technology of which is based on Visible Light Communication (VLC). VLC is a data communication medium, which uses visible light between 400 THz (780 nm) and 800 THz (375 nm) as optical carrier for data transmission and illumination. It uses fast pulses of light to transmit information wirelessly. The main components of this communication system are 1) a highbrightness white LED,

which acts as a communication source and 2) a silicon photodiode which shows good response to visible wavelength region serving as the receiving element. LED can be switched on and off to generate digital strings of 1s and 0s. Data can be encoded in the light to generate a new data stream by varying the flickering rate of the LED. To be more clear, by modulating the LED light with the data signal, the LED illumination can be used as a communication source. As the flickering rate is so fast, the LED output appears constant to the human eye. A data rate of greater than 100 Mbps is possible by using highspeed LEDs with appropriate multiplexing techniques. VLC data rate can be increased by parallel data transmission using LED arrays where each LED transmits a different data stream.

There are reasons to prefer LED as the light source in VLC while a lot of other illumination devices like fluorescent lamp, incandescent bulb etc. are available.
LED has the advantages of:
a) high efficiency
b) design flexibility
c) low power
d) long life
e) fast switching capability
f ) better spectrum performance
g) excellent visibility
h) low cost

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