This was the article which was very well demonstrated in Tedxtalk(https://www.youtube.com/watch?v=iHWIZsIBj3Q). Making use of Light Radiations in place of Radiowaves for regulation our internet.

1. Li-fi
The future of High Speed Internet

2. What is Li-Fi?
• In technical terms, Li-Fi is a visible light communications system that is
capable of transmitting data at high speeds over the visible light
spectrum, ultraviolet and infrared radiation.
• Li-Fi (short for light fidelity).

3. INTRODUCTION
• Li-Fi is a technology for wireless communication between devices using
light to transmit data.
• In terms of its end use the technology is similar toWi-Fi.The key technical
difference is that Wi-Fi uses radio frequency to transmit data.
• Li-Fi can be thought of as a light basedWi-Fi.That is, it uses light instead of
radio waves to transmit information. And instead ofWi-Fi modems, Li-Fi
would use transceiver-fitted LED lamps that can light a room as well as
transmit and receive information.

4. • Using light to transmit data allows Li-
Fi to offer several advantages like
working across higher bandwidth,
working in areas susceptible to
electromagnetic interference
(e.g. aircraft cabins, hospitals) and
offering higher transmission speeds.

5. HISTORY
• Professor Harald Haas coined the term "Li-Fi" at his 2011TED GlobalTalk where he
introduced the idea of "wireless data from every light". He is a Chair Professor of
Mobile Communications at the University of Edinburgh, and the co-founder of
pureLiFi.
• The general term "visible light communication" (VLC), whose history dates back to
the 1880s, includes any use of the visible light portion of the electromagnetic
spectrum to transmit information.
• PureLiFi, formerly pureVLC, is an original equipment manufacturer (OEM) firm set
up to commercialize Li-Fi products for integration with existing LED-lighting
systems.

6. --Harald Haas--

7. History
• On 12th July 2011. He used a table lamp with an LED bulb to transmit a
video of blooming flowers that was then projected onto a screen behind
him. During the event he periodically blocked the light from lamp to prove
that the lamp was indeed the source of incoming data.
• AtTEDGlobal, Haas demonstrated a data rate of transmission of around
10Mbps -- comparable to a fairly good UK broadband connection.Two
months later he achieved 123Mbps.
• Back in 2011, German scientists succeeded in creating an800Mbps
(Megabits per second) capable wireless network by using nothing more than
normal red, blue, green and yellow(RGB).

8. Issues regarding Radio-spectrum
Capacity
Efficiency
Availability
Security

9. • Capacity:-
• Radiowaves.
• Costly and Expensive.
• Less Bandwidth compared to that of any other spectrum.
• Insufficient spectrum for increasing spectrum.
• >>Spectrum is 10000 times greater than that of radio
frequency.<<

10. • Efficiency:-
• Million of basestations consume huge amount of energy for;
• Transmitting the radiowaves.
• To cool the base station cabins.
• 5% efficiency.
• >>Highly efficient since LED consumes less energy.<<

11. • Availability:-
• Available within the range of BaseStations.
• Limited availability.
• Unavailabe in aircrafts.
• >>Light waves available everywhere.<<
• Security:-
• Less secure(passes through the walls).
• >>cannot penetrate through walls.Hence data cannot be
intercepted.<<

13. Radio
Waves
• Limited Bandwidth, cause minor health issues.
Infrared
Rays
• Infrared, due to eye safety regulation, can only be used with low power.
Visible
Rays
• Not yet effectively used.
U.V
Rays
• Ultraviolet light is good for place without people, but other wise dangerous
for the human body.
X
Rays
• X-rays have similar health issues.
Gamma
Rays
• Gama rays cant be used as they could be dangerous.

15. Who can replace Radiowaves for Wireless
communication?
• LED i.e. Light emitting diode can be switched on and off faster since
operating speed of LED is less than 1 μs, than the human eye can detect,
causing the light source to be appear continuously.This invisible on/off
activity enables a kind of data transmission using binary codes. Switching on
and LED is a logical ‘1’, switching it off is a logical ‘0’.It is possible to encode
data in the light by varying the rate at which LED’s flicker on and off to give
different strings of 1’s and 0’s. Modulation is so fast that human eye doesn’t
notice

17. How LI-FI Works ?
• Operational procedure is very simple, if the led is on, you transmit a digital
‘1’, if its off you transmit is ‘0’.The LEDs can be switched on and off very
quickly, which gives nice opportunities for transmitting data. Hence all that
us required is some LED’s and a controller that code data into those LEDs.
We have to just vary the rate at which the LED’s flicker depending upon the
data we want to encode.
• Thus every light source will works as a hub for data transmission.

19. • Further enhancements can be made in this method, like using an
array of LED’s for parallel data transmission, or using mixtures
of red, green and blue LED’s 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(1080p) film in just 30
seconds

20. Types of Li-fi~

22. • Giga-Shower and Giga-MIMO are the other models for in-house
communication.There a transmitter or receiver is mounted into the ceiling
connected to, for example, a media server.
• Giga-Shower provides unidirectional data services via several channels to
multiple users with gigabit-class communication speed over several meters.
This is like watchingTV channels or listening to different radio stations
where no uplink channel is needed. In case Giga-Shower is used to sell
books, music or movies, the connected media server can be accessed viaWi-
Fi to process payment via a mobile device.
• Giga-Spot and Giga-MIMO are optical wireless single- and multi-channel
Hotspot solutions offering bidirectional gigabit class communication in a
room, hall or shopping mall.

24. POTENTIAL APPLICATION OF LI-FI
Li Fi technology is still in its infancy .However some areas where it
seems perfectly applicable are:
1.TRAFFIC LIGHTS :-
• Traffic lights can communicate to the car and with each other. Cars have
LED-based headlights, LED-based back lights, and cars can communicate
with each other and prevent accidents in by exchanging information.

26. 2.INTRINSICALLY SAFE ENVIRONMENT
• Visible Light is more safe than RF, hence it can be used in places where RF
can't be used such as petrochemical plants .

28. 3.Airlines
• 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 is
introduced.

30. 4.ON OCEAN BEDS
• Li-Fi can even wok underwater wereWi-Fi fails completely, thereby
throwing open endless opportunities for military/navigation operations.

31. 5.On Street’s
• There are millions of street lamps deployed around the world. Each of these
street lamps could be a free access point.
• It will reduce your electricity bill and maintainance bill

33. Limitations
• Limitations 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 theVLC systems.
• A major challenge facing Li-Fi is how the receiving device will transmit back
to transmitter.

34. Conclusion
• The possibilities are numerous and can be explored further. If this
technology can be put into practical use , every bulb can be used something
like aWi-Fi hotspots to transmit wireless data.