Li-Fi

By

Mithun Madhusoodanan

�  Li-Fi is transmission of data through illumination.

�  LED Bulb varies in intensity faster than the human eye can follow.

�  LED lights can be switched on and off at high speeds.

�  This property is the basics for Li-Fi

�  LED when on gives binary 1 and off gives binary 0 2

Present Scenario �  We have 1.4 million cellular base

stations deployed

�  We also have 5 billion of mobile

phones

�  Mobile phones transmit 600tb of

data every month

�  Wireless communication has

become an utility like electricity

and water

�  We use it in our everyday life,

private life, business life

�  Currently Wi-Fi uses radio waves

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Issues with radio waves

Capacity

Availability

Efficiency

Security

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Capacity

� We transmit wireless data through radio waves.

� Radio waves are limited.

� Radio waves are scarce and expensive.

� We only have certain range of it.

� With advent of new technologies like 2G,3G,4G we

are running out of spectrum.

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Efficiency

�  There are 1.4 million cellular radio base stations.

�  They consume massive amount of energy.

�  Most of this energy is not used for transmission but for

cooling down the base stations.

�  Efficiency of such a base station is only 5% and that

rise a big problem.

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Availability

� Availability of radio waves or RF signals causes

another concern.

� We have to switch off mobile phones in airplanes.

� Radio waves cannot be used under water

�  It is not advisable to use mobiles at places like

petrochemical plants and petrol pumps.

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Security

� Radio waves penetrates through walls.

� They can be intercepted.

�  If someone has a knowledge and bad intentions

then he may misuse it.

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Alternative to Radio Waves in Electromagnetic spectrum

�  Looking at EM spectrum.

�  Gamma rays are simply dangerous and thus can’t be used for our purpose of communication.

�  X-rays are good in hospitals and can’t be used either. �  Ultra violet rays are sometimes good for our skin but for

long duration it is dangerous. �  Infrared rays are bad for our eyes and are therefore

used at low power levels. �  We have already seen the short comings of radio

waves. �  So we are now left with Visible Rays.

Radio- Waves

Infra- Waves

Visible Rays

Ultra- Violet X-rays Gamma

Rays

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Light for Wireless communication �  Light has been around for millions of years

�  It has created us, has created life and has created all stuffs of life.

�  Light is part of electromagnetic spectrum

�  There are 40 billion light box already installed

�  Flickering lights are annoying but thy may have an upside.

�  Li-Fi uses rapid pulses of light to transmit information wirelessly.

�  It is inherently safe to use and would be great if we can use it for our wireless communication.

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What we have to do? � We have to replace the inefficient fluorescent

lights with new dignitaries of LED lights.

�  It is a semi conductive e-device.

� Light intensity can be modulated at very high

speeds to send data by tiny changes in

amplitude.

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How we do this? � Remote controls have an IR led. �  It creates a single data stream. � Replace remote control with light box. � With this technology we transmits 1000’s of

data stream in parallel at high speeds.

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How it Works?

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Is it a proven technology? �  Yes, this is already proven.

�  Harald Hass demonstrated his invention using an

ordinary table lamp that successfully transmitted

data at speeds exceeding 10Mbps .

�  To prove that the light bulb was the source of data

stream, he periodically blocked the beam of light,

causing the connection to drop.

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Overcoming the four issues in Li-Fi

Capacity �  10000times more spectrum than Radio waves. �  Light box are already present. �  We have the infrastructure available and already

installed.

Efficiency �  Data through illumination and thus data

transmission comes for free. �  Led light consumes less energy. �  High efficient.

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Availability � Light is present everywhere. � Can be used in airplanes �  It can be underwater where radio waves cannot. Security � Light waves doesn’t penetrate through walls. � Can’t be intercepted and misused. � Data is present where there is light.

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Applications

�  Can be used in the places where it is difficult to lay the optical fiber like hospitals. In operation theatre Li-Fi can be used for modern medical instruments.

�  In traffic signals Li-Fi can be used which will communicate with the LED lights of the cars and accident numbers can be decreased.

�  Thousands and millions of street lamps can be transferred to Li-Fi lamps to transfer data.

�  In aircraft Li-Fi can be used to transmit data. �  It can used in petroleum or chemical plants where other

transmission or frequencies could be hazardous.

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Limitations

� There should be line of sight between sender and receiver

� Visible light cannot penetrate through solid objects

�  Interference with other electromagnetic waves makes the transmitting data to distort

� Light cannot approach the range and penetration of radio waves

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Conclusion

The possibilities are numerous and can be explored further. If

this technology can be put into practical use, every bulb can be

used something like Wi-Fi hotspot to transmit wireless data and

we will proceed onwards the

Cleaner, Greener, Safer and Brighter future.

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Thank You For Your Attention!

Li-Fi A Seminar Presentation by Mithun Madhusoodanan

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Questions

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Video Demonstration

Li-Fi Demonstration by Harald Hass at TED talk. 22