CONTENTS:
1.Introduction
2.History
3.Construction of Li-Fi
4.Working of Li-Fi
5.Why only VLC
6.Advantages
7.Limitations and Challenges
8.Applications
9.Conclusion
INTRODUCTION
Li-Fi means light fidelity.
It can be used as light based Wi-Fi.
Instead of radio waves it uses visible rays for transmission.
Data can be transmitted through LED light.
HISTORYLi-Fi is a VLC [Visible Light
Communication] .
It is a technology developed by a team of
scientists including Dr Gordon Povey , Prof.
Harald Haas and Dr Mostafa Afghani at the
University of Edinburgh UK
.
The term Li-Fi was coined by Prof. Haas in
July 2011
Harald Hass, who is considered to be the
Father of Li-Fi says that the heart of Li-Fi
technology lies in the intensity and the potential
of the LEDs
HARALD HASS
Li-Fi consists of four primary sub-
assemblies:
Printed circuit board (PCB)
RF power amplifier (PA)
Bulb
Enclosure
Electrodes
Bulb Dielectric
material
The bulb is embedded in the
dielectric material
Two degradable electrodes are used.
Dielectric material serves two
purposes-waveguide, electric field
concentrator.
Plasma state-emits light of high
intensity.
The operational procedure is very
simple.
If the LED is ON digital 1 is
transmitted, if it is OFF digital 0 is
transmitted.
Lamp driver-codes data into
LED’s.
Photo detector encodes the data
Gamma rays can’t be used as they could be
dangerous.
X-rays have similar health issues.
Ultraviolet light is good for place without people, but
other wise dangerous for the human body.
Infrared, due to eye safety regulation, can only be
used with low power.
Radio waves
Infra-red Rays
Visible Rays
UV Rays
X-RaysGamma
Rays
Limitations And Challenges
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 the VLC systems.A major challenge facing Li-Fi is how the receiving
device will transmit back to transmitter.
APPLICATIONS
Car Lights
oCars with LED based-Head
lights.
oCars communicate – prevent
accidents
Airports:
oWi-Fi will be slow.
oTo avoid these Li-Fi is used.
Visible Light is safer than RF
RF Restricted
Environment
Medical
• Operating rooms don’t allow Wi-Fi.
The possibilities are numerous and can be exploredfurther. If this technology can be put into practical use,every bulb can be used something like a Wi-Fi hotspotsto transmit wireless data.With its magic of light it can make our worldgreener , safer, cleaner and more over a brighter placeto live.