Li- Fi
(Light – Fidelity)
Contents
-
INTRODUCTION
HOW LI-FI IS DIFFERENT ?
HISTORY OF LI-FI
LI-FI CONSTRUCTION
WHY LI-FI COMES ?
HOW LI-FI WORKS ?
LI-FI VS WI-FI
FEATURES
ADVANTAGES
DIADVANTAGES
APPLICATIONS
FUTURE SCOPE
CONCLUSION
Introduction
▸ Li-Fi means “LIGHT FIDELITY”
▸ Li-Fi is fast and cheap optical version
of wi-Fi.
▸ Li-Fi is a technology that uses the
LIGHT EMITTING DIODES (LED) to
transmit the data wirelessly .
▸ Li-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.
How Li-Fi Is Different ?
-
Li-Fi technology is based on LEDs for the
transfer of data.
- The transfer of the data can be with the help of all kind
of light i.e., Light may be Invisible, Ultraviolet or
Visible part of spectrum.
- The speed of the internet is incredibly high and the
user everything in just a few minutes.
History of Li-Fi
This technology was invented by German Physicist
“HARALD HASS”, from the university of Edinburgh, U.K.
- He demonstrated it in the year 2012.
- But, the technology was truly began during the 1990’s in countries like
Germany, Korea & Japan.
- where they discovered LED’s could be retrofitted to send information
UNIVERSITY OF EDINBURGH :-
Li-Fi Construction
▸ The Li-Fi product consists of three primary
subassemblies:▸ Emitter (including bulb)
▸ RF Driver.
▸ Power supply
Function of Bulb Assembly
▸ At the heart of LIFI is the bulb sub-assembly
where a sealed bulb is embedded in a
dielectric material.
▸ The dielectric material serves two purposes:
▸
1) waveguide
▸
2) Electric field
RF Drive
▸ Power
amplifier
(PA)
assembly that uses an
LDMOS device.
▸ Converts electrical energy
into RF power.
▸ The PA is designed for
ruggedness and efficiency.
▸ The RF driver also contains
controls circuit for digital
and analog lighting controls.
A Typical Li-Fi Scenario
Why Li-Fi comes ?
- Due to Issues regarding with Radio frequency Spectrum
- Electromagnetic spectrum
- These are -
Capacity
Availability
Efficiency
Security
Radio Spectrum Issues
Security
• Less secure(passes
through the walls)
Capacity

Radio waves.

Cost and Expensive.

Less Bandwidth compared to other
spectrums.

Insufficient spectrum for increasing
data.
Efficiency

Availability

1.) Transmitting the radio waves
Available within the range of
Base stations.

Limited availability.

Unavailable in aircrafts.
Millions of base stations consume
huge
amount of energy for
2.) To cool the base station cabins

5% Efficiency
Electromagnetic Spectrum
Radio
Waves
Infrared
Rays
Visible
Rays
Ultraviolet
Rays
X- Rays
Gama Rays
• Gama rays cant 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.
•
HENCE WE LEFT WITH THE ONLY THE VISIBLE - LIGHT
SPECTRUM.
WHAT USES CAN
REPLACE
RADIO WAVES FOR
WIRELESS
COMMUNICATION ?
THROUGH LI-FI
-
By the use of li-fi we can replace radio waves for wireless
communication
How Li-Fi Works ?
• Procedure is very simple, if the LED is on , then your device transmit a digit
‘1’ & if it is off, then your device transmit a digit ‘0’.
• The LED can be switched on & off very quickly, which gives nice
opportunities for transmitting data.
• Hence, all that required is some LEDS & a controller that code data into those
LEDS.
Comparison Between Li-Fi vs. Wi-Fi
Features of Li-Fi
•
CAPACITY
- 10,000 Times more spectrum then RW.
- Light boxes are already present, so infrastructure is available already and installed .
•
EFFICIENCY
- Highly efficient because LED consume less energy.
•
AVAILABLITY
- Light is present every where.
- Data is present where light is present.
•
SECURITY
- Light waves does not penetrate through walls.
- Hence they can not be INTERCEPTED.
Advantages of Li-Fi
• It is impossible to achieve more than 10Gbps,
theoretically allowing a high-definition film
to be downloaded in 30 sec.
• MAPS
Mostly powered by LEDs so it is cost efficient
Transmission of data is fast and easy.
Disadvantages of Li-Fi
Presence of light is
essential
There should be line of sight
Works better with fluorescent
light and LEDs but very low
efficiency with bulbs.
Applications of Li-Fi
Street and
traffic
light
Under
water
scenarios
Airplane
scenarios
In RF
restricted
environment
Future Scope
• This research report categories the global VLC technology market
based on component, application and geography.
• Li-fi uses light emitting diodes (LEDs) which are rapidly gaining in
popularity for standards light bulbs and other domestic and commercial
purposes . They are expected to be ubiquitous in 20 years.
• Still under research :• What will be effect of interference from external light sources like sun
light and normal bulbs ?
• What about the limited bandwidth of existing copper cable used for
electrical connection.
Future Scope
• Where do the connections uplink, how serious are the
modifications needed to the power grid.
• How will other devices React if you Inject a high frequency in to
Main ?
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 a Wi-Fi hotspots to transmit wireless data.
Thanks !
Any questions?
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