Li-Fi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission. It is a viable alternative to traditional Wi-Fi networks and provides higher speeds and more secure data transmission compared to radio frequency-based Wi-Fi. Li-Fi works by varying the intensity of light from an LED to transmit digital data and can support data rates exceeding 1 Gbps. It has various applications in areas where radio frequencies are regulated or limited and provides illumination as well as wireless connectivity.

1. :
“LIGHT FIDELITY(LI-FI)”

2. Contents
Introduction
History
Need for LI-FI
Working
LI-FI Vs WI-FI
Applications
Conclusion
References

3. Introduction
What is LI-FI ?
• LI- FI means – LIGHT FIDELITY
• Lightis used instead of radio-waves to transmit information.
• LI- FI is transmission of data through illumination, sending data through a led bulb that
varies in intensity faster than human eye can follow.
• Li-Fi is based on Visible Light Communication (VLC).
• VLC is a data communication medium, which uses the visible light between 400 THz
(780 nm) and 800 THz (375 nm) as optical carrier for data transmission.
• Provides illumination as well as data communication.

4. HOW LI-FI WORKS
• Its working is much simply explained as follows:
• If the LED is on, the digital 1 is transmitted.
• And if it is off, the digital 0 is transmitted.
• 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 1 and 0.

5. HISTORY
• The technology truly began in 1990’s.
• Germany, Korea and Japan were the first three countries to discover LED’s
could retrofitted to send information.
• German Physicist “HARALD HASS”, from the university of Edinburgh,
U.K was the first to tell the world the potential to use light for
communication.
• He demonstrated it in the year 2011.

6. NEED FOR LI-FI
Issues regarding radio spectrum
CAPACITY
• With the advent of new technologies like 3g ,4g we are running out of spectrum.
• That’s why radio waves are now becoming expensive.
EFFICIENCY
• There are 1.4 millions cellular radio base stations .
• Efficiecy of each base station is just 5%.
• Most of the energy is not used for transmission but rather for cooling down the
base station.

7.  SECURITY
• radio waves can penetrate through walls and hence can
be intercepted.
• anyone with knowledge and bad
intention can misuse it.
 AVALILABLITY
• we have to switch off mobiles in
aircrafts.
• it is also not advisable to use mobiles atpetrol pumps.

8. Expensive
Limited BW
Less Secure
Low power
applications
Is not used
generally
Used for
Hospitals
Dangerous for
human body
• This is not used so far.
• Safe to use.
• Larger Bandwidth

9. • Gamma rays can’t be used as they could be dangerous.
• X-rays have similar health issues.
• Ultraviolet light is good for place without people, but
otherwise dangerous for human body.
• Infrared can only be used with low power due to eye safety
regulation.
• Hence we left with onlyVLC i.e. “Visible Light Spectrum”.

10. The LI-FI product consists of 4 primary
sub-assemblies:
Bulb
RF power amplifier circuit (PA)
Printed circuit board (PCB)
Enclosure
In RF driver
PAis used to convert electrical energy into RF Power.
PAis desgined for ruggedness and efficiency.
PAalso contains control circuit for digital and
analog lightning.
Led bulb work as a projector of data.
ENCLOSURE
PA
LED
PCB
LI-FI CONSTRUCTION

11. HOW LED TRANSMITS DATA
An RF (radio-frequency) signal is generated by the solid-state PAand is guided into
an electric field about the bulb.
The led is embeded with dielectric material.
The work of dielectric material – guide RF energy and focus it to the bulb’s centre.
The high concentration of energy in the electric field vaporizes the contents of the
bulb to a plasma state at the bulb’s centre.
This controlled plasma generates an intense source of light.

12. • All the data from Internet is streamed into lamp
driver.
• Data from internet is used to modulate the
intensity of LED light source.
subtle
optical
• The photodetector picks up the signal.
• The receiver dongle then converts the tiny
changes in amplitude into a data stream.
IMPLEMENTATION
• Thus by fast and subtle variations of current,
optical output can be made to vary at extremely
high speed

13. Sr. No. Parameters Light Fidelity Wireless Fidelity
1. Speed for data
transfer
Faster transfer speed
(>1gbps)
DataTransfer
speed(150mbps)
2. Medium for data
transfer
Light Radio
3. Spectrum Range 10,000 times broad
spectrum as compare to
radio frequency
Less than visible light
spectrum
4. Cost Cheaper because free
band doesn’t need
license as it uses light
Expensive in
comparison to LI-FI as
it uses radio spectrum
5. Operating Frequency Hundreds of
THz
2.4 GHz

14. Li-Fi connector and router are themain
components for a network
Room connector:
• Optical signals cannot penetrate through walls, in order
to provide an optical WLAN, rooms need to be
connected with each other
• Li-Fi room connector is a replicator, which sends the data
stream from one side of the wall to the other side via an
optical fiber.
• For smaller rooms, connector act as the only Li-Fi
hotspot in the room
LI-FI NETWORKS

15. • Serves as a connector to external link like
DSL.
• Covers a radius of about 20 meters
• The transmission speed is 100 Mbps.
• Suitable for small office or home use
LI -FI ROUTERS

16. OVERCOMINGTHE ISSUES WITH RW IN LI-FI
CAPACITY
• 10000 times more spectrum than RW. light boxes are already present, so infrastructure is
available already and installed.
EFFICIENCY
• Highly efficient because led consumes less energy.
AVALILABLITY
• LIGHT IS PRESENT EVERYWHERE.
• DATA IS PRESENT WHERE LIGHT IS PRESENT.
SECURITY
• LIGHT WAVES DOESNOT PENETRATE THROUGH WALLS.
• HENCE THEY CAN’T BE INTERCEPTED.

17. APPLICATIONS
LIFI can be used in
• sensitive areas such as aircrafts for data transmission without causing
interference
• Places where it is difficult to lay optical fibers like operation theaters
• Traffic scenarios, thereby reducing accidents
• Underwater applications where radio waves cannot propagate.
• Industries like petrochemical plants, nuclear power plants , petrol pumps etc

18. TRAFFIC SCENARIO
• In traffic scenario, LIFI can be used to
communicate with the LED lights of cars .
• Cars can have LED-based headlights, backlights
and can communicate with each other.
• This might prevent accidents, by exchanging
information, when the vehicles are too close
• Using LIFI, Street lights can be used to send
information about the road condition to the car.

19. HOME AND OFFICE
• In home and small offices, Li-Fi can be used to
communicate with devices like
• Laptops ,Internet access , HD video streaming ,
Printer.
AIRCRAFTS
• The whole airways communication are performed
on the basis of radio waves.
• Hence passengers face the problem in
communication media.
• This problem can be overcome by using Li-Fi,
since light waves will not interfere with radio
waves

20. PROVEN TECHNOLOGY
• Harald has demonstrated Li-Fi using an ordinary
table lamp and a computer located below the
lamp.
• He successfully transmitted data at speed
exceeding 10Mbps using light waves from LED
light bulbs .
• Also he periodically blocked the beam of light,
causing the connection to drop.

21. ADVANTAGES
• Data rate greater than 10 Gbps; Theoretically allowing HD film to be downloaded in 30
seconds .
• Can be used anywhere, even in RF restricted areas; Since light waves will not interfere with
radio waves.
• Mostly LED light bulbs are used, which consumes less energy. Hence cost efficient.
• As light waves cannot penetrate through walls, the data cannot be intercepted; Thus provides
secured communication.
• Efficient alternative to radio based wireless; since it is quick and reliable.

22. LIMITATIONS
• Visible light cannot penetrate through solid objects.
• A major challenge of Li-Fi is how the receiving device will transmit back to
transmitter.
• Interferences from external light sources like sunlight, in the path of
transmission will cause interruption in the communication.
• Data transmission can be easily blocked by any object placed in front of LED
source.

23. CONCLUSION
Thus, if Li-Fi technology can be put into practical use, every bulb can be used
as an alternative toWi-Fi hotspots. It provides simple, faster and efficient
wireless data communication. Li-Fi will make us to proceed towards the
cleaner, greener, safer and brighter future.

24. REFERENCES
• http://en.wikipedia.org/wiki/Li-Fi
• seminarprojects.com/s/seminar-report-on-Li-Fi
• http://teleinfobd.blogspot.in/2012/01/what-is-lifi.html
• technopits.blogspot.comtechnology.cgap.org/2012/01/a-lifi-world
• www.lificonsortium.org
• the-gadgeteer.com/2011/08/LI-FI

25. THANK YOU