li-fi
Post on 21-Sep-2014
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Wireless Communication Systems Using Light as a MediumTRANSCRIPT
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
. 3
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