LI FI- LIGHT FIDELITY
LI-FI is transmission of data through illumination ,ie sending data through an LED light bulb that varies in intensity faster than human eye can follow

The new LIFI receiver is designed with solar panel which receives the light with data.
Baud rate of operation is 9600
Distance covered is maximum 15 feet without any obstacle.
Moderate sunlight will affect distance of reception.Trimpot on receiver board can be adjusted to increase the distance.

Simple mode of working : Conect Tx of LIFI to Rx of TTL ,  Rx of LIFI to Tx of TTL
Power supply 12v ( 5v regulator is on board)
LED source is soldered to Tx board.
ATMEGA8 IC used on Tx & Rx boards for handling serial data.
Li-Fi can be thought of as a light-based Wi-Fi.
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.

HOW LI FI WORKS?

Operational procedure is very simple, if the led is on, it transmits a digital 1, if its off  transmits a 0.The LEDs can be switched on and off very quickly, which gives nice opportunities for transmitting data.
Hence all that us required is some LEDS and a controller that code data into those LEDs. We have to just vary the rate at which the LED’s flicker depending upon the data we want to encode

On one end all the data on the internet will be streamed to a lamp driver when the led is turned on the microchip converts the digital data in form of light A light sensitive device (photo detector) receives the signal and converts it back into original data. This method of using rapid pulses of light to transmit information wirelessly is technically referred as Visible Light Communication

LIMITATIONS :
1. Interferences from external light sources like sun light, normal bulbs, and opaque materials in the path of transmission will cause interruption in the communication.
2. light can't pass through objects
3.A major challenge facing Li-Fi is how the receiving device will transmit back to transmitter.