This document provides an overview of visible light communications (VLC), also known as Li-Fi. It discusses the history and invention of VLC, how VLC works by transmitting data through light bulb illumination at speeds too fast for the human eye to detect, its advantages over Wi-Fi like high security and availability anywhere light is present, and potential applications including use in traffic lights, hospitals, airplanes and underwater. The document also outlines the components needed for a VLC system including LEDs, photodiodes and control circuitry, and discusses future developments and limitations such as the need for line of sight transmission.

1. VISIBLE LIGHT COMMUNICATIONS(VLC)

2. Outline of VLC
 Advantages
 Disadvantages
 Experimental Setup
 Future developments
 Limitations and challenges
 Conclusion
 References
 History
 Introduction
 Frequency Spectrum
 What is LI-FI??
 Why VLC??
 Features
 Applications
 Working process

3. This technology was invented by
German Physicist
“HARALD HASS”, from the
university of Edinburgh,
U.K.
 He demonstrated it in the year
2012.
HISTORY
UNIVERSITY OF EDINBURGH:

4. INTRODUCTION
• Very simply, if the LED is ON, user can transmit a digital string of 1, if
it’s OFF then user can transmit a string of 0.
• It can be switched ON and OFF very quickly, which gives instant
opportunity for transmitting data.
• It is possible to encode data in the light by varying the rate at which
the LEDs flicker ON and OFF to pass different strings of 1s and 0s.
• The modulation is so fast that the human eye doesn’t notice.
• There are over 14 billion light bulbs used across the world, which
needs to be replaced with LEDs ones that transmit data.

6. Radio
Waves
Infrared
Rays
Visible
Rays
Ultraviolet
Rays
X- Rays
Gama
Rays
WHY ONLY VLC
 Gama rays cant be used as they could be dangerous.
X-rays have similar health issues.
Ultraviolet light is good for place without people, but other wise dangerous
for the human body.
Infrared, due to eye safety regulation, can only be used with low power.
HENCE WE LEFT WITH THE ONLY THE VISIBLE - LIGHT SPECTRUM.

7. FEATURES
Transmit data serially at 57600 baud rate
Distance of 1 feet to 10 feet can be achieved
Low power requirement
No effect on human health
Highly secure compared to Wi-Fi
High data density because visible light can be
well contained

8. What is LI-FI ??
LI-FI is the transmission of
data through illumination by
taking the fibre out of fibre
optics by sending data through
a LED light bulb.
This varies in intensity faster
than human eye can follow.
It is the fast and cheap
communication system which
is optical version of the wi-fi.

9. Applications of VLC

10. Application Areas
Li Fi technology is still in its infancy .However some areas
where it seems perfectly applicable are:-
POTENTIAL APPLICATION OF LI-FI
1 . Traffic Lights :
Traffic lights can communicate
to the car and with each other.
Cars have LED-based
headlights, LED-based back
lights, and cars can
communicate with each other
and prevent accidents in by
exchanging information.

11. Potential Application of Li-Fi
 Hospitals(In Few Medical Equipements) :

12. Potential Application of Li-Fi
2. Intrinsically Safe Environment :
Visible Light is more safe than RF, hence it can be used in
places where RF can't be used such as petrochemical plants .

13. Potential Application of Li-Fi
3. Airlines :
Whenever we travel through airways we face the
problem in communication media ,because the whole airways
communication are performed on the basis of radio waves. To
overcome this drawback on radiowaves , li-fi is introduced.

14. Potential Application of Li-Fi
4. On Ocean Beds :
Li-Fi can even work underwater were Wi-Fi fails
completely, thereby throwing open endless opportunities for
military/navigation operations.

15. Application
• There are millions of street lamps deployed around the world.
 Street Lamps (As free Access Points) :
• Each of these street lamps could be a free access point.

16. Working Process
Operational procedure is very simple, if the led is
on, you transmit a digital 1, if its off you transmit a 0.
The LEDs can be switched on and off very quickly,
which gives nice opportunities for transmitting data.
Hence all that us required is some LEDs and a
controller that code data into those LEDs. We have to
just vary the rate at which the LED’s .
Flicker depending upon the data we want to encode .
Thus every light source will works as a hub for data
transmission .

17. How LI-FI Works?

18. Components
• Arduino
• Quad OP-AMP(LM324)
• Photo Diode
• LED’s
• Potentiometers(3386c)
• 8bit pic data controller(12F1840)
• Jumpers
• Resistors,capacitors
• Thyristor(IRF3205)

19. RECEIVER TRANSMITTER
TRANSMITTER AND RECEIVER

20. TRANSMITTER CIRCUIT

21. CIRCUIT DIAGRMS OF RECEIVER

22. Snap shot of VLC

23. Capacity:
10000 times more spectrum than RADIO WAVES.
Light boxes are already present, so infrastructure is available already
and installed.
Availability:
Light is present everywhere.
Data is present where light is present
Efficiency:
Highly efficient because LED consumes less
energy
ADVANTAGES OF LI-FI

24. Advantages
High Security
Easy To Use
Fast Data Transfer
Reliable
Harmless ness
Low Cost

25. DE-MERITS
•light can't pass through objects
•Connectivity while moving
•Interferences from external light
sources like sun light, normal bulbs,
and opaque materials in the path of
transmission will cause interruption
in the communication.

26. FUTURE DEVELOPMENTS
The concept of Li-Fi is currently
attracting a great deal of interest.
Efficient alternative to radio-based
wireless.
Li-Fi is an emerging technology which is
quick and reliable.
Air waves are clogged so let’s use light
waves.
So lets proceed to LI FI for a brighter and
greener future.

27. Limitations or Challanges
 Light can't pass through objects .
 Interferences from external light sources like sun light, normal
bulbs, and opaque materials in the path of transmission will cause
interruption in the communication.
 Total bandwidth of visible light is not fully used still it
needs to be improved
 A major challenge facing Li-Fi is how the receiving device
will transmit back to transmitter.
 Li-Fi requires line of sight.

28. 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 a Wi-Fi hotspot.
we will proceed toward the cleaner, greener, safer and brighter
future.
This may solve issues such as the shortage of radio-frequency
bandwidth.
 Allows internet where traditional radio based wireless isn’t
allowed such as aircraft or hospitals.

29. Thanks for your time
Any queries