Light–Fidelity (Li-Fi) is a technology that uses the Light Emitting Diodes (LEDs) to transmit wireless data instead of radio waves. This is going to be the future of wireless data transmission.

1. Light Fidelity (Li-Fi) Technology
By RAJASHEKAR VITTAL
Email: rajanzb@gmail.com

2. CONTENTS
 INTRODUCTION
 ELECTROMAGNETIC SPECTRUM?
 ISSUES REGARDING RADIO SPECTRUM AND WHY
VLC?
 DEVICES USED
 BASIC CONCEPTS AND WORKING OF LI-FI
 COMPARISION BETWEEN LI-FI AND WI-FI
 POTENTIAL APPLICATIONS
 CHALLENGES FOR LI-FI
 CONCLUSION

3. INTRODUCTION
 Light–Fidelity (Li-Fi) is a technology that uses the Light
Emitting Diodes (LEDs) to transmit the data wirelessly
instead of radio waves.
 Li-Fi technology came into existence in 2011.
 This technology was invented by German physicist Harald Haas.
 Researchers have reached data rates of over 500 megabytes per
second using a standard white-light LED.
 It allows wireless communication without the use of radio
waves, which can be dangerous in places like oil platforms,
underwater and on planes.
 Li-Fi can be thought of as a light-based Wi-Fi.

5. Why VLC?(Visible Light for Communication)
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.
Radio Spectrum is congested but the demand for wireless data
double each year .Every thing, it seems want to use wireless data but
the capacity is drying up.
Issues regarding Radio Spectrum. (Cont.)

6. Issues regarding the Radio Spectrum
Capacity:
With the increasing number of mobile connections the availability of the
spectrum is getting congested.
Radio waves form only a small fraction of the entire EM spectrum thus
making the problem even worse.
Efficiency:
For every unit of energy consumed the data transmitted is relatively less.
The data speeds in the current system can only reach up to a few hundreds
of megabits per second.
Security:
These radio waves can easily penetrate through the walls, thus letting
anonymous users to use the network.
Economic:
Due to limited availability of the radio waves the tariff rates are relatively
costlier.
There can be many issues during the spectrum allocations.

7. Hence we are left with only the VISIBLE - LIGHT
SPECTRUM which is not harmful for humans.
DEVICES USED
Devices which are used for transmission purpose in VLC
are visible light LEDs(up to 500 Mbit/s) or fluorescent
lamp(10bit/s).
Devices used for reception purpose in VLC are photo
diodes and image sensors.
Amplification and processing unit to amplify the signal.

8. BASIC CONCEPTS AND WORKING
LED ie Light emitting diode can be switched on and off
faster since operating speed of LED is less than the
human eye can detect, causing the light source to be
appear continuously.
Switching the LEDs ON and OFF gives nice opportunities
for transmitting data using binary codes ‘0’ and ‘1’.
A controller placed can code data into those LEDs.
Usage of an array of LEDs for parallel data transmission,
or using mixtures of red, green and blue LEDs to alter the
light’s frequency.

9.  On one end all the data on the internet will be streamed to a lamp
driver when the led is turned on, the microchip controller converts the
digital data in form of light through LEDs.
 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

10.  LI-FI has upper hand due to parallel data transmission.

11. COMPARISION BETWEEN LI-FI AND WI-FI
Sl.No Parameters Light Fidelity Wireless Fidelity
1 Speed for data
transfer
Faster transfer speed (>1
Gbps)
Data Transfer speed (150
Mbps)
2 Medium through
which data transfers
occurs
Used Light as a carrier Used Radio spectrum
3 Spectrum Range Visible light spectrum has
10,000 time broad spectrum
in comparison to radio
frequency
Radio frequency spectrum
range is less than visible
light spectrum.
4 Cost Cheaper than Wi-Fi because
free band doesn’t need license
and it use light.
Expensive in comparison to
Li-Fi because its uses radio
spectrum.
5 Network topology Point to point Point to point
6 Operating frequency Hundreds of Tera Hz (THz) 2.4 GHz

12. POTENTIAL APPLICATIONS
Visible Light is more safe than RF, hence it can be used in places where
RF can't be used such as petrochemical plants .
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 can be implemented.

13. 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 (using some alerts) and prevent accidents in by exchanging
information.

14. CHALLENGES FOR LI-FI
 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

15. CONCLUSION
If his technology can be put into practical use, every bulb
can be used something like a Wi-Fi hotspot to transmit
wireless data .
The concept of Li-Fi is currently attracting a great deal of
interest very efficient alternative to radio-based wireless.
Researchers are developing micron sized LED in which case
a 1000 micron LEDs can communicate as much information
as a single LED given the same space.
This may solve issues such as the shortage of radio-
frequency bandwidth and also allow internet where radio
based wireless isn’t allowed such as aircrafts or hospitals.

16. THANK YOU
By: RAJASHEKAR VITTAL
Email: rajanzb@gmail.com