This document discusses Li-Fi technology, which uses visible light communication to transmit data wirelessly. Li-Fi was invented by German physicist Harald Haas in 2012 and uses LED lights to transmit data at speeds over 150 Mbps by varying the intensity of light faster than the human eye can detect. It has several advantages over Wi-Fi such as higher speed, more available spectrum, more security as light does not pass through walls, and is more efficient. Li-Fi has already been demonstrated successfully in transmitting data using an ordinary table lamp.

1. technology
High speed bidirectional fully
networked wireless
communication.
Project submitted by:
Vinay Kumar Gattu.
KNRR(ECE)

2. Introduction:
 LI-FI is a technology that uses the light emitting
diodes to transmit the data wirelessly.
 LI-FI is fast and cheap optical version of Wi-Fi
,based on visible light communication(VLC).
 VLC is a data communication medium, which uses
the visible light between 400 THz (780 nm) and
800 THz (375 nm) as optical carrier for data
transmission.

3.  By this technology the led bulb having power of
one watt will distribute internet to four systems
at a time.
 The led bulbs having microchips will transmit
internet with speed of 150mbps.

4. Diagrammatic representation of li-fi

5. LI-FI Environment:

6. WHO INVENTED IT ?
 This technology was invented by German physicist
HARALD HAAS , from the University of Edinburgh.
 He demonstrated it in the year 2012.

7. How LI-FI works:

8.  The heart of this technology is a new generation high
brightness LED’S.
 These LED’S varies in intensity (that is gets on and
off) so fast that a human eye cannot detect it.
 If LED is ON , then we transmit logic 1, and if LED is
OFF , then we transmit logic 0.
 A controller is connected at the back side of these
LED bulbs to code data to these LED’S.

9. LI-FI Equipment

10. LI-FI VS WI-FI
 LI-FI has a High speed
data transfer rate over
1gbps.
 Wi-Fi has a data
transfer rate of
maximum 54
mbps.
DATA TRANSFER
SPEED
• Why so much difference?

11. • LI-FI has an upper hand due to parallel data
transmission.

12. Part of EM spectrum they use
LI-FI
 LI-FI uses the
visible light
portion of the EM
spectrum.
WI-FI
 Wi-Fi use the
radio wave portion
of EM spectrum

13. Issues with radio wave:
 Capacity
• With advent of new technologies like 3G, 4G we are
running out of spectrum.
• This is because radio waves are now becoming
expensive.

14.  Efficiency
 There are 1.4 million cellular radio base stations.
 Efficiency of each base station is just 5%.
 Most of the energy is not used for transmission
but rather for cooling down the base station.

15.  Security
• Radio waves can penetrate through walls
and hence can be intercepted.
• Any one with skills of hacking may misuse
it.
 Availability
• We have to switch off mobiles in aircrafts.
• It is not advisable to use mobiles at petrol
bunks.

16. ALTERNATIVE OF RADIO WAVES
CAN IT BE INFRARED WAVES ?
Ir Waves Are Harmful For Our Eyes
Hence Used At Very Low Power

17. CAN IT BE UV RAYS?
• UV rays are harmful for our skin and cannot be used
for long duration.
CAN IT BE GAMMA RAYS ?
Gamma Rays Are Radioactive And Are
Dangerous.
CAN IT BE X-RAYS ? NO
SO WE ARE LEFT ONLY WITH VISIBLE
LIGHT SPECTRUM.

18. Advantages of li-fi which are limitations to
RW
CAPACITY
• 10000 Times More Spectrum Than Rw.
• Light Boxes Are Already Present, So
Infrastructure Is Available Already And
Installed.
EFFICIENCY
Highly Efficient Because Led Consumes
Less Energy.

19. AVAILABLITY
• Light Is Present Everywhere.
• Data is present where light is present.
SECURITY
• Light Waves Does not Penetrate
Through Walls.
• Hence they can’t be intercepted.

20. Advantages of LI-FI
• You Can Use Li-fi In Hospitals And Aircrafts Also.
• Cheaper Then Wi-Fi , Since Visible Light Spectrum Is
A Free Spectrum Band.
• No License Needed.
• Thousands And Millions Of Street Lamps Can Be
Converted To Li-fi Hotspots.

21. IS THIS A PROVEN TECHNOLOGY ?
 Yes This Already Proven.
 HARALD HAAS DEMONSTRATED HIS INVENTION
USING AN ORDINARY TABLE LAMP THAT
SUCCESSFULLY TRANSMITTED DATA AT SPEEDS
EXCEEDING 10mbps USING LIGHT WAVES FORM LED
LIGHT BULBS TO A COMPUTER LOCATED BELOW THE
LAMP. To Prove That The Light Was The Source Of
The Data Stream He Periodically Blocked The Beam
Of Light , Causing The Connection To Drop.