Li-Fi is a technology that uses visible light communication and light-emitting diodes (LEDs) to transmit data wirelessly. It can provide higher speeds than Wi-Fi and has advantages like no interference with other wireless networks, more bandwidth availability, and more secure connections. Li-Fi works by varying the intensity of light from an LED to transmit digital signals. A photodetector converts the light signals into electrical signals to decode the data. Potential applications of Li-Fi include use in aircraft cabins, petrochemical plants, hospitals, lecture halls, homes, and underwater environments.

1. LI-FI TECHNOLOGY
BY
MANISH JAISWAL
B110950EE

2. CONTENTS :
• Introduction
• Why LI-FI ??
• Difference Between The Technologies
• Components
• Block diagram
• Working process
• Applications
• Advantages
• Limitation
• Conclusion
• References

3. INTRODUCTION TO
What is exactly ?

4. Introduction…
 A German physicist, Dr. Harald Haas, has
come up with a solution to address the
problems with WIFI networks, he calls
“Data Through Illumination”
 In simple terms, Li-Fi can be thought of as a
light-based Wi-Fi.
 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 information.

5. Introduction…
• LiFi 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.
• 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 1s and 0s.
• LI-FI comes under VLC (VISIBLE
LIGHT COMMUNICATION)

6. If led is on , then we transmit a digital signal 1, and if
the led is off , then we transmit a digital signal 0.

7. Why VLC ??

8. Why LI-FI ?
• Present Scenario:
More than 1.8 Million More than 338 Million

9. Drawbacks Of Before Technologies
Issues Regarding Radio Spectrum:

10. Cont…
o Capacity
Radio waves
Cost and expensive
Less bandwidth compared to other spectrums
Insufficient spectrum for increasing data
o Efficiency
Millions of base stations consume huge amount of energy
for
1. Transmitting the radio waves
2. To cool the base station cabins
5 % efficiency

11. Cont…
o Availability
Availability within the range of base stations
Limited availability
Unavailability in aircrafts
o Security
Less secure(passes through the walls)

12. Difference Between The Technologies

14. Major Components of a LIFI Communication System
• Source
A high brightness white LED, acts as a communication source It’s guided by the PCB
and powered by PA and is enclosed in an aluminum enclosure
 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
plasma generates an intense source of light.
 RF power amplifier circuit (PA): An RF (radio-frequency) signal is
generated by the solid-state PA(Power Amplifier) and is guided into an electric
field about the bulb.
 Printed circuit board (PCB): The PCB controls the electrical inputs and
outputs of the lamp and houses the microcontroller used to manage different
lamp functions.
 Enclosure: All of these subassemblies are contained in an aluminum enclosure

15. Cont…
• Receiver
 A silicon photodiode, which shows good response to visible wavelength
region serving as the receiving element.

16. Block Diagram:
RECEVING SIGNALS

17. How
LI-FI
Works ?

18. How LI FI Works…

19. How LI FI Works…
• On one end all the data on the internet will be streamed to a lamp
driver when the led is turned on the microchip converts the digital
data in form of light.
• A light sensitive device (photo detector) receives the signal and
converts it back into original data. This method of using rapid pulses
of light to transmit information wirelessly is technically referred as
Visible Light Communication

20. Cont…

21. Function Of The Bulb:
• At the heart of LIFI™ is the bulb sub-assembly where a sealed bulb is
embedded in a dielectric material.
• This design is more reliable than conventional light sources that insert
degradable electrodes into the bulb.
• The dielectric material serves two purposes; first as a waveguide for the RF
energy transmitted by the PA (power amplifier) and second as an electric
field concentrator that focuses energy in the bulb.
• The energy from the electric field rapidly heats the material in the bulb to a
plasma state that emits light of high intensity and full spectrum

22. Working…
 White LED light bulbs: Li-Fi is typically implemented using white LED light
bulbs at the downlink transmitter which normally used for illumination only by
applying a constant current.
 Optical output is varied at extremely high speed: The LEDs can be switched on
and off very quickly which gives nice opportunity for data transfer in the form of
Binary code. Hence, by fast and subtle variations of the current, the optical output
can be made to vary at extremely high speeds. This very property of optical
current is used in Li-Fi setup.

23. Cont…
 Operational Procedure: The operational procedure is very simple-, if the
LED is on, you transmit a digital 1, if it’s off you transmit a 0.

24. Cont…
 Hence it is possible to encode the data into the LED’s by using a controller
,we just have to vary at which LED’s flicker depending on the data we
want to encode to give different strings of 0’s and 1’s.

25. Data transfer in binary code
• UK researches say that using a micro-LED light bulb they have achieved a
data transmission speed of 10Gbps using LI-FI.

26. • 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 –
meaning one can download a full high-definition film in just 30
seconds

27. Illustration

28. OUTLOOK OF LI-FI
Li-Fi communication with other Devices

29. Properties of LIFI
 Light-based Wi-Fi: LIFI 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 information. Since simple light bulbs
are used, there can technically be any number of access
points.
 Unutilized electromagnetic spectrum is used: This technology
uses a part of the electromagnetic spectrum that is still not
greatly utilized. The Visible Spectrum.
 No major ill effect: Light is in fact very much part of our lives for
millions and millions of years and does not have any major ill
effect.

30. HOW THE BASIC LIGHT IS CONVERTED INTO ELECTRICITY
• Vacuum equations, electromagnetic waves and speed of
light.
• Figure is a 3D diagram shows a plane linearly polarized
wave propagating from left to right with the same wave
equations from left to right.
• Where E = E0 sin(−ωt + k ⋅ r) and B = B0 sin(−ωt + k ⋅ r)
• In a region with no charges (ρ = 0) and no currents (J =
0), such as in a vacuum, Equation is reduced Maxwell’s
equations.

31. Cont…
• Taking the curl (∇×) of the curl equations, and using the curl of the curl identity ∇×(∇×X) =
∇(∇·X) − ∇2X we obtain the wave equations.
• Which identify
• C is the speed of light in free space. In materials with relative permittivity εr and relative
permeability μr, the phase velocity of light becomes
• which is usually less than c

32. Potential Application Area:
IN AIRCRAFT CABIN IN PETROCHEMICAL INDUSTRIES

33. In Hospitals In Traffic

34. Under Water
In Home , Offices
and Schools

35. In Lecture Hall

36. Advantages:

37. Limitation or Challenges :
• Light can not pass through opaque objects.
• Interference from external source like sun light, normal bulbs opaque
materials.
• High installation cost of VLC.

38. The possibilities are numerous and
can be explored further. If his
technology can be put into practical
use, every bulb can be used something
like a Wi-Fi hotspot to transmit
wireless data and we will proceed
toward the cleaner, greener, safer and
brighter future

39. References:
• http://www.ted.com/talks/harald_haas_wireless_data_from_every_light
_bulb.html
• www.ijacc.org
• http://oledcomm.com/lifi.html
• http://en.wikipedia.org/wiki/Li-Fi
• International Journal of advances in computing & communications, vol
1, 2013,page no-12