LiFi is cellular wireless networking (re)using lights. Specifically, light emitting diodes (LEDs) are used in LiFi as visible light transmitters. LiFi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission. LiFi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. Li-Fi uses common household LED (light emitting diodes) light bulbs to enable data transfer, boasting speeds of up to 224 gigabits per second.

1. LI-FI
BY:
PRAGATI RASTOGI

2.  WHAT IS LI FI??
 GENESIS
 IMPLEMENTATION
 WORKING
 APPLICATION AREAS
 COMPARISON WITH OTHER TECHNOLOGIES
 LIMITATIONS
 CONCLUSION
Outline

3. What is LI-FI…??
LI-FI (LIGHT FIDEALITY) is a “Visible Light Communication”
technology.
It is transmission of data through illumination, i.e. sending data
through a LED light bulb that varies in intensity faster than human
eye can follow.
LI-FI can be thought of as a light based Wi-Fi. That is, it uses light
instead of radio waves to transmit information. And instead of Wi-Fi
modems, LI-FI would use transreceiver-fitted LED lamps that can
light a room as well as transmit and receive information.

4. Genesis of LI-FI
Harald Haas, a professor at the
University of Edinburgh who
began his research in the field
in 2004, gave a debut
demonstration of what he
called a Li-Fi prototype at the
TED Global conference in
Edinburgh on 12th July 2011.
Prof. Harald Hass

5. 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.
At TED Global, Haas demonstrated a data rate of transmission of
around 10Mbps. Two months later he achieved 123Mbps.

6. Li-Fi is typically
implemented using LED
light bulbs at the downlink
transmitter.
All that required is some
LEDs and a controller that
code data into those LEDs.
Implementation

7. Operational procedure is very simple, if the LED is on, you transmit a
digital 1, if it’s off you transmit a 0.
LED i.e. Light emitting diode can be switched on and off faster since
operating speed of LED is less than 1 μs, far lasser 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
Hence all that required is some LEDs 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.
How it works..?

8. Controller
/

9. Comparison with Other Technologies

10. Radio
Waves
Infrared Visible
Light
Ultra
Voilet
X-Rays Gamma
Rays
Cosmic
Rays
Expensive,
Limited
bandwidth
can only be
used with low
power, due to
eye safety
regulation.
dangerous
for the
human body
dangerous
for the
human body
Harmful,
Causes
health issues
o Not used so far,
o Safe to use,
o Larger Bandwidth, 10,000 times broader spectrum in
comparison of radio frequency which is used for Wi-Fi,
o Free spectrum
Fig: Electromagnetic Spectrum

11. Application Areas
 HOSPITALS
 AIRLINES
 UNDERWATER
 POWER PLANTS

12.  Light can't pass through opaque 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.
Limitations & Challenges

14. THANKYOU