With the vast growing gadgets, their usage and their developments led to the advancement in the Wi-Fi which provides a technology so called Li-Fi.Li-Fi is a technology that makes use of LED light which helps in the transmission of data much more faster and flexible than data that can be transmitted through Wi-Fi.Light reaches nearly everywhere so communication can also go along with light freely. Light Fidelity is a branch of optical wireless communication which is an emerging technology. By using visible light as transmission medium, Li-Fi provides wireless indoor communication. The bit rate achieved by Li-Fi cannot be achieved by Wi-Fi.. Dr herald Haas ,the professor of mobile communications at the university of Edinburgh school of engineering ,first time publically displayed the proof of Light Fidelity(Li-Fi) ,a method of Visible Light communication(VLC). Li-Fi is the transfer of data through light by taking fiber out of fiber optics and sending data through LED light.

1. Presented by:
Dolat Singh
10105EN059
IIT(BHU)-Varanasi

2. Agenda
 Introduction
 History
 Present Scenario
 Working process
 Advantages
 Disadvantages
 Applications
 Present Research
 Conclusion

3. WHAT IS Li – Fi ?
 LI-FI is transmission of data through illumination,
sending data through a LED light bulb that varies
intensity faster than human eye can follow

5. History of Li-Fi
 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 Haas

6. Present Wireless Communication
 Radio spectrum
 1.4 Million base stations, 5 billion Mobile stations
 600Tb data every month

7. Wireless Communication, a utility
 Personal life
 Business life
 Hospitals
 Research and development
 Security

8. Issues regarding Radiospectrum

9. Capacity
 Radiowaves
 Cost and Expensive
 Less Bandwidth compared to other spectrums
 Insufficient spectrum for increasing data
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

10. Availability
 Available within the range of Base stations
 Limited availabity
 Unavailable in aircrafts
Security:
 Less secure(passes through the walls)

12. How Li-Fi ?
 Normal light power is replaced by LED light power
 The LED bulb will hold a micro-chip that will do the job of
processing the data.
 The light intensity can be manipulated to send data by tiny changes
in amplitude
 Properties of LED: (Fundamental property of LI-FI)
1.Intensity can be modulated into very high speeds and
varying amplitudes
2.LED can be switched on and off with very high speed

13. Block Diagram
Data
Modulation
(PPM/FSK)
Data
Demodulation
(PPM/FSK)
Light
Source
Photo
Detector

15. LI-FI Data transmission

16. Transmitting element
 LED
 Fluorescent Lamp

17. Receiving element
(Detector)
 Avalanche Photo Diode
 Image Sensors

18. Advantages
• Larger bandwidth (10,000 times the radio
bandwidth)
• High efficiency
• More availability
• Highly secure

19. Disadvantages
 Connectivity while moving
 Multiuser support
 Dimming
 Shadowing

20. APPLICATIONS

21.  In RF restricted Environments.
 Hospitals
 In vehicles and traffic lights, reducing accidents.
 Street lamps(as free access points).
 In Aircraft cabins.

22. Present Research
 Chi Nan, an information technology professor at Shanghai's
Fudan University, experimented with using the light from a
one-watt LED bulb to transmit data with a microchip and can
produce data speeds of up to 150 megabits per second, One
lightbulb can be used to connect four computers to the
Internet.The scientists are scheduled to demonstrate a set of
example li-fi kits at the China International Industry Fair on
Nov. 5 in Shanghai.

23. Conclusion
•Overcomes the limitations of radio spectrum
•High speed of 10 Gbps can be achieved
•Li fi can solve the foressential problems
of wireless communications these days
•Enable ever smaller cells without the need
for new infrastructure.

24. References
[1] seminarprojects.com/s/seminar-report-on-lifi
[2] http://en.wikipedia.org/wiki/Li-Fi
[3] http://teleinfobd.blogspot.in/2012/01/what-is-lifi.html
[4] technopits.blogspot.comtechnology.cgap.org/2012/01/11/alifiworld/
[5] www.lificonsortium.org/
[6] the-gadgeteer.com/2011/08/29/li-fi-internet-at-thespeedoflight/
[7] en.wikipedia.org/wiki/Li-Fi
[8] www.macmillandictionary.com/buzzword/entries/Li-Fi.html