if u've any doubts..mail me @ akhil2369492@gmail.com

2. CONTENTS
ж
ж
ж
ж
ж
ж
ж
ж
ж
ж
ISSUES REGARDING RADIO SPECTRUM
INTRODUCTION
PRINCIPLE OF LI-FI TECHNOLOGY
VISIBLE LIGHT COMMUNICATION
CONSTRUCTION and WORKING OF Li-Fi
COMPARISON BETWEEN LI-FI AND WI-FI
FUTURE APPLICATIONS
CHALLENGES FOR LI-FI
CONCLUSION
REFERENCES

3. ISSUES REGARDING THE USE OF
RADIO SPECTRUM
CAPACITY
AVAILABILITY
EFFICIENCY
SECURITY

4. INTRODUCTION
ж
ж
ж
ж
Light–Fidelity (Li-Fi) technology came into existence in 2011.
The term was f irst used by Harald Haas in his TED Global talk
on Visible Light Communication.
In October 2011 a number of companies and industry groups
formed the Li-Fi consortium, to promote high-speed optical
wireless systems.
Researchers at the Heinrich Hertz Institute in Berlin, Germany,
have reached data rates of over 500 megabytes per second using
a standard white-light LED.

5. INTRODUCTION (contd..)
ж It allows wireless communication without the use of radio
waves, which can be dangerous in places like oil platforms,
underwater and on planes
ж Li-Fi can be thought of as a light-based Wi-Fi.
HARALD HAAS

6. PRINCIPLE OF LI-FI TECHNOLOGY
ж Heart of Li-Fi technology is high brightness LED‟s.
ж The LED bulb will hold a micro-chip that will do the job of
processing the data.
ж The on-off activity of LEDs enables a kind of data
transmission using binary codes.
ж Switching on an LED is a logical „1‟;switching it off is a
logical „0‟.
ж A light sensitive device (photo detector) receives the signal and
converts it back into original data.

7. fig(i)..Sending of data [2]

8. VISIBLE LIGHT COMMUNICATION
ж
ж
Li-Fi is a faster and cheaper version of Wi-Fi, which is
based on visible light communication (VLC).
The visible light communication is a data communication
technique using visible light between 400 THz and 800 THz
as an optical carrier for data transmission.

9. WHY VLC ?
Radio
Waves
ж
ж
ж
Infrared
Rays
Visible Rays
Ultraviolet
Rays
X- Rays
Gama Rays
Gama rays,X-rays,Ultraviolet rays are harmful for the human
body.
Infrared rays are also dangerous, due to eye safety regulation,
and can only be used with low power.
Radio waves are expensive and they are less secure.
HENCE WE ARE LEFT WITH ONLY THE VISIBLE LIGHT SPECTRUM which is not harmful for humans .

10. Devices used in visible light communication
ж
ж
ж
Devices which are used for transmission purpose in VLC are
visible light LED and fluorescent lamp.
This technology uses fluorescent lamps to transmit signals at
10bit/s, or LED‟s for up to 500 Mbit/s.
Devices which are used for reception purpose in visible light
communication are photo diodes and image sensors.

11. CONSTRUCTION and WORKING OF Li-Fi
ж
ж
ж
ж
Li-Fi is implemented using white LED light bulbs at downlink
transmitter.
By fast variations of the current, optical output can be made to
vary at extremely high speeds.
An overhead lamp fitted with an LED with signal processing
technology streams data embedded in its beam at ultra high
speeds to the photodiodes.
A receiver dongle then converts the tiny changes in amplitude
into an electrical signal, which is then converted back into a data
stream & transmitted to a computer or mobile device.

12. fig(ii)..Working of Li-Fi [1]

13. fig(iii)..Illustration of data transfer in Li-Fi [3]

14. COMPARISON 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
Used Light as a carrier
Used Radio spectrum
data transfers occurs
3
Spectrum Range
Visible light spectrum has 10,000 time Radio frequency spectrum range is
broad spectrum in comparison to
less than visible light spectrum.
radio frequency
4
Cost
Cheaper than Wi-Fi because free band Expensive in comparison to Li-Fi
doesn’t need license and it use light.
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

15. FUTURE APPLICATIONS
ж
ж
ж
ж
Li-Fi can be used in sensitive areas such as aircraft for data
transmission without causing interference.
It can be used in places where it is difficult to lay optical fibres
like operation theaters .
In traffic scenario, Li-Fi can be used to communicate with the
LED lights of cars and might alert drivers when other vehicles
are too close so accident numbers can be decreased.
It will improve conditions for those working in underwater
oil rigs where radio waves can‟t propagate.

16. FUTURE APPLICATIONS(contd..)
ж
ж
Thousands and millions of street lamps can be transferred to
Li-Fi lamps to transfer data.
It can be used in petroleum and chemical plants where other
transmission or frequencies could be hazardous.

17. CHALLENGES FOR LI-FI
ж
ж
ж
ж
Presence of Light is essential.
Li-Fi requires line of sight.
It is easily blocked by somebody simply walking in front of
LED source.
The grand vision: “LED lights with added microchips will let
us transmit thousands of data streams in parallel, enabling us to
access the Internet on smartphones wherever there is a light
source”.[1]

18. CONCLUSION
ж
ж
ж
ж
Researchers are developing micron sized LED .
1000 micron sized LED can fit into area required by
1sq. mm large single LED.
A 1 sq.mm sized array of micron sized LED‟s could therefore
communicate 1000×1000 (i.e. a million) times as much
information as a single 1mm LED.
Li-Fi consortium believes it is possible to achieve more than
10Gbps, theoretically allowing a high definition film to be
downloaded in 30 seconds.

19. REFERENCES
[1] NEW EPOCH OF WIRELESS COMMUNICATION: LIGHT
FIDELITY
Authors: Megha Goyal, Dimple Saproo, Asha Bhagarshra,
Journal: International Journal of Innovative Research in Computer and
Communication Engineering ISSN/EISSN: 23209798 23209801
Year:2013 Volume: 1 Issue: 2
http://ijircce.com/upload/2013/april/52_New%20Epoch.pdf
[2] Li-Fi (Light Fidelity)-The future technology In Wireless
communication
http://www.ripublication.com/ijaer.htm
[3] 'Li-Fi' provides a light bulb moment for wireless web - CNN.com

20. ANY
QUERIES..???