2. WHAT IS Li-Fi…..???
Li-Fi = Light-Fidelity
Li-Fi is transmission of data through
illumination, sending data through a
LED light bulb that varies intensity
faster than human eye can follow
2
4. HISTORY OF Li-Fi
The technology truly began during
the 1990's in countries like
Germany, Korea, and Japan
where the
German scientist discovered
LED's could be retrofitted to send
information. Prof. Harald
Haas
6. Radio spectrum is congested but the demand for
wireless data double each year . Everything , it
seems want to use
Wireless data but the capacity is drying up !!!!
Present Scenario
1.4 Million Base
Stations
5 Billion
9. Efficiency
Millions of base stations consume huge
amount of energy for :
1.Transmitting the radio waves
2.To cool the base station cabins
5% Efficiency
10. Availability
Available within the range of
Base stations
Limited availabity
Unavailable in aircrafts
Security
Less secure(passes through the walls)
11.
12. Why only VLC ?
Gama rays cant be used as they could
be dangerous.
X-rays have similar health issues.
Ultraviolet is good for place without
people.
Infrared, due to eye safety regulation,
can only be used with low power.
13. HENCE WE LEFT WITH THE
ONLY THE VISIBLE - LIGHT
BUT
Who can replace Radio Waves For
Wireless Communication
?????????
16. On one end all the data on the internet will be
streamed to a lamp driver when the led is turned on
the microchip converts the digital data in form of light
.
16
17. A photo detector receives the signal and converts it back
into original data. This method of using rapid pulses of
light to transmit information wirelessly is technically
referred as Visible Light Communication
21. 1-Traffic Lights :
Traffic lights can communicate to the car and
with each other.
Cars have LED-based headlights, LED-based
cack
lights, and cars can communicate with each
other
and prevent accidents in by exchanging
information.
22. 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 .
Editor's Notes
X rays and gamma rays have high frequencies.
The internal energy of the atom is the sum of the energies of each electron.
The energy of each electron depends on the values of five quantum numbers: n, l, s, nl, ns
An atom can change from one energy level to another by emitting or absorbing a photon with an energy equal to the energy difference between the two levels
Ionizing radiation as radiation from high-energy photons (X and gamma rays), and charged particles.
Or, Ionization energy: amount of energy required to remove the least-bound electron from the atom.
n is the shell no. or principal quantum no.
Units of μ is m-1
Bones attenuate X-rays to a much greater degree than the soft tissue of the lungs, and appear brighter on the image.
(a) The set-up for planar radiography.
(b) An anti-scatter grid is placed directly in front of the detector to reduce the contribution from scattered X-rays.
(c) An example of a chest radiograph: there is far greater attenuation in bone than in tissue, and excellent tissue contrast.
