Li-Fi (Light Fidelity)

Li-Fi (Light Fidelity)

using Visible Light

Communication

by Thiruvarasan.kLi-Fi

Li-Fi

Visible light communication The visible light communication (VLC) refers to the

communication technology which utilizes the visible light source as a signal transmitter, the air as a transmission medium, and the appropriate photodiode as a signal receiving component

Visible light communication is a way of communication that uses visible light wavelength ranging from 780nm-380nm(385THz~789THz if converted to frequency).

Li-Fi

IMPORTANCE OF VISIBLE LIGHT Visible light waves are the only electromagnetic waves we can see. We see

these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light.

Larger bandwidth ( 10,000 times the radio bandwidth)

Li-Fi

In VLC, the LED bulbs act as an Access Point.

The Photodiode is the Receiver which receives the flickering Light Rays from the LED bulb.

Here the mobile is embedded with Photodiode receiver which can convert the flickering (ON / OFF) of LED bulb into Os and 1s.

LED bulbs flicker at a very fast rate which the human eye cannot see.

Li-Fi

What is Li-Fi ? Li-Fi means “Light Fidelity”.

At the heart of this technology is a new generation of high brightness light-emitting diodes.

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.

LI-FI ( Light-Fidelity ) is transmission of data through illumination ,sending data through a LED light bulb that varies in intensity faster than human eye can follow.

German Physicist, Dr.Harald Haas a professor in university of Eddinburgh who began his research in the field in year 2004.

Li-Fi

How Li-Fi works ?The operation procedure is very simple, if

the LED is on, you transmit a digital 1, if it's off you transmit a digital 0.

They can be switched on and off very quickly, which gives nice opportunities for transmitting data.

Li-Fi

Functioning of Li-Fi The functioning of new Li-Fi technology is just simple. You will have a light source at one end like a LED an a photo detector (Light Sensor) on the other end.

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Li-Fi Environment

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Applications of Li-FiApplications of Li-Fi

Li-Fi

Aircraft cabins• Used in airlines: Generally in airlines mobile phones

can’t be used as they can effect the radars which are main way of communication

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Traffic System

• Used in traffic lights which can communicate with cars to avoid accidents.

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Public Internet Hotspot

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Hospitals Li-Fi can be used in Operation theatre as it does not interfere with the radio waves of the electronic instruments in operation theatre.

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Advantages of Li-Fi• Li-Fi is operating with Visible Light which consists of larger

bandwidth upto 10,000 times more than Radio Waves

• High speed data transfer upto 10 Gbit/s or 1.25 GB/s

• Li-Fi signals can be blocked by walls, so there is less risk for data leaking or hacking

• Low cost communication as the LED bulbs act as Access Point• Li-Fi can be used without interference from radio frequency.

Li-Fi

Disadvantages• Light should be always ON while using the Li-Fi visible light

communication.

• The Receiving photodiode should in line of sight with the LED bulb.

• It works better with LEDs and fluorescent lights but works with low efficiency with incandescent bulbs.

Li-Fi

References• http://en.m.wikipedia.org/wiki/Visible_light_communication• http://en.m.wikipedia.org/wiki/Li-Fi• http://www.lificonsortium.org/