3. 1
INTRODUCTION
1. Li-Fi Light Fideality.
2. Li-Fi is transmission of data
through illumination,i.e,sending
data through a LED light bulb
that varies in intensity faster
than eye can follow.
4. The technology truly began during 1990โs
In the countries like Germany, korea and
Japan where they discovered LEDโS could be
Retrofitted to send information.Harald Hass
Continues to wow the world with the
Potential to use light for communication.
7. X-rays
Radio
waves
Infrared
rays
Gamma raysUltraviolet
rays
Visible rays
Why only VLC
โขGama rays canโt be use as they could be
Dangerous.
โขX rays has similar health issues.
โขUV rays is good for place without people,but
other wise dangerous for human body.
โขIF rays due only eye safety regulation can
only be used with low power.
8. WHAT IS LI-FI?
โขLight +Wifi =Li-Fi.
โขLED is an light emitting diode can be switched on and off faster since operating
speed is less than 1us,than the human eye can detect ,causing the light source to
be appear continuously .this invisible on and off enables a kind of data
transmission using binary codes.switching on LED is logic 1 and switching off LED
is logic 0.It is possible to encode the data in light by varying rate at which LEDโs
flicker on and off to give different strings of 1โs and 0โs .Modulation is so fast that
human eye does not notice.
9. How LI-FI works?
Thus every light source will works as a hub for data transmission.
The operational procedure is very simple if
LED is on you transmit a digit 1,if its off u
transmit a digit 0.The led can be on and off
very quickly which gives nice opportunities for
transmitting the data.Hence all that us required
is some LEDS and a controller that code data
into that LEDS.We have just vary the rate at
which the LED flicker depending upon the data
we want to encode.
14. APPLICATIONS
Traffic lights
Traffic light communicate to
the car and with each
other .Cars have LED
based head lights ,car can
communicate with each
other and prevent
accidents .
Air craft cabins
Whenever we travel
through airways we face
problem in communication
media ,because the whole
airways communications
are performed on the basis
of radio waves.To overcome
this drawback on radio
waves.li-fi is introduced.
Ocean beds
LI-FI even work under
water where Wi-Fi fails
completely, thereby
throwing open endless
opportunities for military
/navigation operation.
Street lamps
There are millions of street
lamps developed around
the world .Each of this
street lamps could be a free
access point.
RF restricted
environment
Visible light is more safe
than RF ,hence it can be
used in places where RF
canโt be used such as
petrochemical plants.
15. โข Light canโt pass through the object.
โข Interference from external light sources like
sunlight ,normal bulbโs, and opaque materials in the
path of transmission will cause interruption in
communication.
โข High installation cost of VLC systems.
โข A major challenge facing Li-Fi is how the receiving
device will transmit back to transmitter.
Limitationsโฆ
LIMITATIONS
16. CONCLUSION
Finally
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.
