Li-Fi is transmission of data through illumination by taking the fiber out of fiber optics by sending data through a LED light bulb that varies in intensity faster than the human eye can follow. Li-Fi, as it has been dubbed, has already achieved blisteringly high speed in the lab. The term was first used in this context by Harald Haas in his TED Global talk on Visible Light Communication.

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Li-Fi
Data Through
Illumination
Presented By:
S. Jyoti Hembrom
14010581
7th sem, ETC
VSSUT Burla

2. Contents
• Introduction: What is Li-Fi?
• History of Li-Fi
• Working of Li-Fi
• Construction of a Li-Fi system
• Benefits of Li-Fi over Wi-Fi
• Applications of Li-Fi
• The Li-Fi room connectors
• Challenges faced by Li-Fi
• Conclusion
• Reference
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3. Introduction
• Li-Fi stands for Light Fidelity.
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4. What is Li-Fi?
• Basically, it’s a visible light communication
system that uses LED lights to transmit data
with out wires.
• Li-Fi uses visible light spectrum which is 1,000
times larger than the Radio spectrum.
• That means, Li-Fi network virtually has an
unlimited capacity hence it also promises to
be a cheaper, faster and safer alternative to
radio wave communication.
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5. A possible Li-Fi environment in an
office
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6. History of Li-Fi
• The term was coined by German physicist Dr.
Harald Haas during a TED Talk on 12th July
2011 when he outlined the idea of using light
bulbs as wireless routers.
• He used a table lamp with an LED bulb to
transmit a video of clouds that was then
projected onto a screen.
• During the event he periodically blocked the light
from lamp to prove that the lamp was indeed the
source of incoming data.
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8. History of Li-Fi
• He demonstrated a data rate of transmission
of around 10Mbps.
• Two months later he achieved 123Mbps.
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9. Working of Li-fi
• High brightness LEDs are the heart of Li-Fi
technology.
• If the LED is ‘ON’, binary data ‘1’ is transmitted
and if the LED is ‘OFF’ binary data ‘0’ is
transmitted.
• Plus, these LEDs can be switched on and off at
very high speeds for transmitting data.
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10. Working of Lifi
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Block Diagram illustrating Li-fi technology

11. Working of Li-fi
• There is an LED at one end and a photo detector on the
other.
• The photo detector registers a binary ‘1’ when the light
is on and a binary ‘0’ when the light is off.
• Flashing the LED numerous times provides data rates in
the range of hundreds of Mbps.
• For processing the data, the LED bulb holds a micro
chip to convert & encode the data into light by varying
the flickering rate of the light.
• The photo detector receives these light signals,& then
they are amplified, processed & converted back to
digital form which the machine can interpret.
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12. Construction of Li-fi
• The Li-Fi system basically comprises two main
parts – the transmitter and the receiver.
• A high brightness white LED is used as the
transmitting element
• A silicon-based photo-diode with good sensitivity
to visible light waves is used as the receiving
element.
• Switching the LEDs on and off can make them
generate digital strings with different
combination of 1s and 0s.
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13. Construction of Li-Fi
• By simply varying the flickering rate of the
light, the LEDs work as a sender by modulating
the light with the data signal.
• However, the LED output will appear constant
to humans because they are made to flicker at
a phenomenal speed (millions of times per
second) and it’s impossible for human eye to
detect this frequency.
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14. Construction of Li-Fi
The Li-Fi product (or the emitter system)
comprises four primary sub-assemblies:
• Bulb
• RF power amplifier circuit (PA)
• Printed circuit board (PCB) and
• Enclosure
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15. Construction of Li-Fi
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16. Construction of Li-Fi
• The Printed circuit board (PCB) controls the electric
input and output of the lamp, and houses the
microcontroller which manages all the functions of the
lamp.
• A radio-frequency signal produced by the power
amplifier is directed into the electric field of the bulb.
• As a result of the high concentration of energy in the
electric field, the contents of the bulb will get
vaporized into a plasma state at the bulb’s centre.
• And this controlled plasma in turn will produce an
intense source of light.
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17. Construction of Li-Fi
• All of these sub-assemblies are enclosed in an
aluminum case as shown in the below block diagram.
• It comprises of a sealed bulb embedded in a dielectric
material
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18. Construction Of Li-Fi
• Li-Fi Bulb sub-assembly:
It comprises of a sealed bulb embedded in a
dielectric material, which serves two purposes.
One, it acts as a waveguide for the radio-
frequency energy transmitted by the power
amplifier.
Two, it acts as an electric field concentrator that
focus the energy into the bulb.
The collected energy will rapidly heat the
material in the bulb to a plasma state, eventually
emitting high intensity light of full spectrum.
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19. Li-Fi vs Wi-fi
Researchers have already achieved data rates of
more than 10 Gbps with Li-Fi, which is 250 times
faster than the fastest existing broadband!
SPEED:
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20. Li-fi vs Wi-fi
Visible light ranges from 430 THz to 770 THz.
The visible light spectrum has 1,000 times more
bandwidth than radio waves spectrum which is
used by Wi-fi. Plus, it’s unlicensed and free to use.
BANDWIDTH:
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21. Li-fi vs Wi-fi
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Data density is a measure of the quantity of
information bits that can be stored .
Li-Fi has about 1000 times more data density than
Wi-Fi since visible light don’t spread out or interfere
with other electromagnetic waves.
DATA DENSITY:

22. Li-Fi vs Wi-Fi
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Visible light does not pose any health hazards to
living beings. Also, unlike Wi-Fi, Li-Fi don’t create
Electromagnetic Interference (EMI) problems, and
so it can be used anywhere in any environment.
SAFETY:

23. Li-Fi vs Wi-Fi
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Li-Fi technology is far more secure than the old
Wi-Fi. Light waves don’t travel through walls and
hence people passing by will not be able to
connect and piggyback off of your connection.
SECURITY:

24. Applications of Li-fi
• Mobile Connectivity: Mobiles, laptops, tablets,
and other PDAs can easily connect with each
other. The short-range network of Li-Fi can yield
exceptionally high data rates and higher security.
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25. Applications of Li-fi
• Aviation: Using Li-Fi, aircraft passengers can
access high-speed internet via lights fitted over
their seats. It can even be used to integrate the
passenger’s smartphones with an In-flight
Entertainment (IFE) system.
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26. Applications of Li-fi
• Hazardous Environments: Li-Fi is intrinsically safe
to use in hazardous environments such as
petrochemical plants, nuclear power plants,
mines etc. where Wi-Fi is prohibited.
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27. Applications of Li-fi
• Hospital and Healthcare: Unlike Wi-Fi, Li-Fi
doesn’t emit any electromagnetic
interference. And so it will not interfere with
medical equipments like MRI scanners.
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28. Applications of Li-fi
Underwater Communication: Li-fi can also work
underwater where Wi-Fi doesn’t work at all.
Li-fi has thrown open a world of possibilities
for military/navigation operations.
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29. Applications of Li-fi
• Vehicles & Transportation: Li-Fi technology
can be easily used for vehicle-to-vehicle and
vehicle-to-roadside sensor communications
for road safety and traffic management
system.
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30. The Li-Fi Room Connector
• The Li-Fi room connector is a replicator which
sends the data stream from one side of the wall
to the other via an optical fiber cable, connecting
the two room connectors on each side of the
wall.
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31. Challenges faced by Li-Fi
• It requires a perfect line-of-sight to transmit
data
• Opaque obstacles on pathways can affect data
transmission
• Natural light, sunlight, and normal electric
light can affect the data transmission speed
• Light waves don’t penetrate through walls and
so Li-Fi has a much shorter range than Wi-Fi
• High installation cost
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32. References
• www.techtreme.com
• www.techyworld.in
• www.hitricks.com
• www.techworld.com
• www.lificonsortium.org
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33. Conclusion
• Although there’s still a long way to go to make
this technology a commercial success, it promises
a great potential in the field of wireless internet.
• It promises to solve the problem of lack of
spectrum space and low internet connection
speed.
• Plus, it will also allow internet access in those
places or fields where radio based wireless isn’t
allowed.
• One thing’s for sure, Li-Fi is the future of internet.
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Thank You….
Any queries?