The document discusses Li-Fi, a technology that transmits data through light using LEDs, offering high-speed, bidirectional communication. It highlights advantages like solving radio frequency congestion and providing secure transmission, while also addressing challenges such as light obstruction and high installation costs. Applications of Li-Fi include traffic lights, safe environments, and public internet hotspots, suggesting a future where every light source could serve as a data transmission hub.

1. SEMINAR ON
LI-FI
Presented By -
Ayush Varshney
1611030018
Btech 4th Year
Electronics Engineering
IERT EDD, Prayagraj
Presented To -
Mr. Nurmesh Bhartiya
Assistant Professor
IERT EDD

2. Contents
 Introduction
 What is LiFi ?
 Why is it requied ?
 How LiFi Works
 LiFi Construction
 Li-Fi Vs Wi-Fi
 Applications of LiFi
 Advantages
 Limitations or Challenges
 Conclusion
 Refrences

3. Page  3

4. Introduction
The technology truly began
during the 1990's in
countries like Germany,
Korea, and Japan where
they discovered LED's
could be retrofitted to send
information. Harald
Haas continues to wow the
world with the potential to
use light for
communication
HARALD
HASS

5. On 12th July 2011. He used a table lamp with an LED
bulb to transmit a video of blooming flowers that was
then projected onto a screen behind him. During the
event he periodically blocked the light from lamp to
prove that the lamp was indeed the source of incoming
data.
At TEDGlobal, Harald Haas demonstrated a data rate
of transmission of around 10Mbps -- comparable to a
fairly good UK broadband connection. Two months later
he achieved 123Mbps.
Back in 2011 German scientists succeeded in creating
an800Mbps (Megabits per second) capable wireless
network

6. WHAT IS LI –
FI ?LIGHT FIDEALITY
• LI-FI is transmission of data through
illumination ,ie sending data through a
LED light bulb that varies in intensity
faster than human eye can follow.
• Li-Fi is bidirectional , high speed and
fully networked wireless communications
similar to Wifi, Li-Fi is a subset of optical
wireless communication (OWC) and can
be a complement to RF communication
(WiFi or Cellular network ), or a
replacement in contexts of data
broadcasting .

8. WHY IT IS REQUIRED?
1.4 Million 5 Billion
• Radio Spectrum is congested but the
demand for wireless data double each year
.Everything, it seems want to use wireless
data but the capacity is drying up.

12. Radi
o
Wave
s
Infrare
d
Rays
Visibl
e
Rays
Ultraviole
t
Rays
X-
Rays
Gam
a
Ray
s
 Gama 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 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 only the Visible-
Light Spectrum.

13. LED i.e., Light emitting diode can be switched on
and off faster since operating speed of LED is less
than 1 μs, than the human eye can detect, causing
the light source to be appear continuously. This
invisible on-off activity enables a kind of data
transmission using binary codes. Switching on and
LED is a logical ‘1’, switching it off is a logical ‘0’.It
is possible to encode data in the light by varying the
rate at which LED’s flicker on and off to give
different strings of 1s and 0s. Modulation is so fast
that human eye doPagee 1s4 n’t notice
Basic concepts

14. How LI-FI
Works
?
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. Wehave to
just vary the rate at which theLED’s flicker depending
upon the data we want to encode
Thus every light source
will works as a hub for
data transmission

16. Further enhancements can be made in
this method, like using an array of LEDs
for parallel data transmission, or using
mixtures of
red, green and blue LEDs to alter the
light‘s frequency with each frequency
encoding a different data channel.
Such advancements promise a
theoretical speed of 10 Gbps –

18. LI FI CONSTRUCTION
The LI FI product consists of 4 primary sub-assemblies:
• Bulb
• RF power amplifier circuit (PA)
• Printed circuit board (PCB)
• Enclosure
3-The PCB controls the electrical inputs and outputs of the lamp and
houses the microcontroller used to manage different lamp functions.
2- An RF (radio-frequency) signal is generated by the solid-state PAand
is guided into an electric field about the bulb. The high concentration of
energy in the electric field vaporizes the contents of the bulb to a plasma
state at the bulb’s center; this controlled pasma generates an intense
source of light. All of these subassemblies are contained in analuminum
enclosure.

19. LiFi Vs Wi-Fi
• Li-Fi can be thought of as a
light- based Wi-Fi. That is, it
uses light instead of radio
waves to transmit information.
• And instead of Wi-Fi modems, Li-
Fi would use transceiver-fitted
LED lamps that can light a room
as well as transmit and receive

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

23. 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 .

2

24. 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
overcomes this drawback on radioways , li-fi is introduced.

25. There are millions of street lamps deployed
around the world.
Each of these street lamps could be a free
access point.
 PUBLIC INTERNET
HOTSPOTS

26. ADVANTAGES OF LI-FI
 Li-Fi can solve problems related to the insufficiency of
radio frequency bandwidth because this technology
uses Visible Light spectrum that has still not been
greatly utilized.
 High data transmission rates of up to 10 Gbps can be
achieved.
 Since light cannot penetrate walls, it provides privacy
and security that Wi-Fi cannot.
 Li-Fi has low implementation and maintenance osts.

27. Limitations or
challenges
-# 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.
#High installation cost of the VLC systems
#A major challenge facing Li-Fi is how the
receiving device will transmit back to
transmitter.

28. CONCLUSI
ON
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 hotspots to
transmit wireless data.

29. REFREN
CES
1..http://www.electronicsforu.com/electronicsforu/ci
rcuitarchives/view_article.asp?sno=778&title%20=
%20Li-
Fi%3A+A+New+Paradigm+in+Wireless+Communi
cation&b_type=new&id=12042
2. http://en.wikipedia.org/wiki/Li-Fi
3. International Journal of advances in computing
& communications, vol 1, 2013,page no-12
www.ijacc.org

30. Page 
38