2. • CONTENTS
- History of wireless communication.
- Current wireless technologies and it’s limitation.
- What is Li-Fi and How it works?
- Triplet or triple speed Li-Fi.
- Li-Fi vs Wi-Fi.
- IoT enabled by Li-Fi.
- Other Application areas of LiFi.
3. • History of wireless communication.
• Prehistoric: Fires, Beacons, Smoke signals, Communication
drums, Horns.
• 5th century : Pigeon post
• 1672: First experimental acoustic (mechanical) telephone
• 1790: Semaphore lines (optical telegraphs)
• 1867: Signal lamps
• 1877: Acoustic phonograph
• 1838: Electrical telegraph.
• 1896: First practical wireless telegraphy systems
• 1927: Television
4. • 1927: First commercial radio-telephone service, U.K.–U.S.
• 1962: Commercial telecommunications satellite.
• 1964: Fiber optical telecommunications
• 1969: Computer networking
• 1981: First mobile (cellular) phone network
• 1983: Internet
• 1998: Mobile satellite hand-held phones
• 2003: VoIP Internet Telephony
•2011: LiFi (introduced the idea),
•
Commercialization in Indian market is possible by 2020.
5. • Radio spectrum is congested, but the
demand for wireless data doubles
each year.
• US Federal Communications
Commission has warned of a
potential spectrum crisis because Wi-
Fi is close to full capacity, Li-Fi has
almost no limitations on capacity.
• Current wireless technologies and it’s
limitation.
6. • What is Li-Fi and How it works?
1. History :
• Professor Harald Haas coined the term "Li-Fi" in 2011 TED Global
Talk where he introduced the idea of "wireless data from every light“.
• In September 2013, a press release said that Li-Fi, or VLC systems in
general, do not require line-of-sight conditions.
• VLC technology was exhibited in 2012 using Li-Fi. By August 2013,
data rates of over 1.6 Gbit/s were demonstrated over a LED.
7. • In April 2014, the Russian company Stins Coman announced the
development of a Li-Fi wireless local network called BeamCaster.
Their current module transfers data at 1.25 gigabytes per second
(GB/s) but they foresee boosting speeds up to 5 GB/s in the near
future.
• In 2014 a new record was established by Sisoft (a Mexican company)
that was able to transfer data at speeds of up to 10 GB/s across a light
spectrum emitted by LED lamps.
• Li-Fi market is projected to have a compound annual growth rate of
82% from 2013 to 2019 and to be worth over $6 billion per year by
2019.
8. 2. Why only Visible light Spectrum?
•Gama rays, X-rays cant be used as they could be dangerous.
•Ultraviolet light is good for place without people, but other wise
dangerous for the human body.
•Hence we left with the only the visible light spectrum.
(430-770Thz, 390 to 700 nm)
9. 3. Standards :
•Like Wi-Fi, Li-Fi is wireless and uses similar 802.11 protocols.
•It uses ultraviolet, infrared and visible light communication (instead of
radio frequency waves), which has much bigger bandwidth.
•Earlier VLC is modeled with IEEE 802.15.7 standard, now its out of
date due to technological developments in field of optical wireless
communication.
•The introduction of OFDM means that a new drive for standardization
of optical wireless communications is required.
10. 4. How its work?
•The major components of this
technology are LED light bulbs and a
photo detector.
•LED bulbs are used to
transmit data and the photo detector is
used to detect the flash light from
the LEDs.
11. • Initially the data that we want to transmit are encoded to binary 0’s
and 1’s.
• The binary digits are then fed into LED bulbs.
• When LED light is switched ON, the binary 0’s and 1’s are
transmitted via LED flash.
• These flashes are then detected by the photo detector.
• The photo detector transfers the binary data for further amplification
in order to decode the binary digits.
12. • As Li-Fi system is based on IM/DD
therefore Avalanche Photo Detector (APD)
is more effective. as compare to PIN based PD.
• APDs can be thought of as photodetectors
that provide a built-in first stage of
gain through avalanche multiplication.
From a functional standpoint, they can be
regarded as the semiconductor analog of
photomultipliers.
13. 5. SCENARIO BASED INDOOR LI-FIARCHITECTURE DESIGN
1. Fixed LP :
Figure A shows User U1 and U2 both are
connected to single LP.
Figure B shows 2 different LP assigned
to U1 and U2 .
2. Movable LP :
The moveable LP is an approach in which
LED bulb can rotate at a certain angle to
adjust the coverage area according to the
requirement of receiver placement.
14. 3. Hybrid LP :
Hybrid approach can also be used by
deploying both moveable and fixed LP
at a same time as shown in fig.
17. • Triplet or Triple speed LiFi
• Einstein theory of relativity state
if an object is able to travel at the speed
of light then time would stop relative to the
object, but not to an observer.
Photons don't experience time.
Then How is it possible? if nothing is faster than the light.
18. • CSK (Color shift Keying) Modulation technique
• Color shift keying (CSK), outlined
in IEEE 802.15.7, is an intensity
modulation based modulation scheme
for VLC.
• CSK is intensity-based, as the
modulated signal takes on an instantaneous
color equal to the
physical sum of three (red/green/blue)
LED instantaneous intensities.
19. ∫ Red + Green + Blue = White
d/dx white = Red + Green + Blue
20. • CSK can be construed as a form of frequency shifting.
• instantaneous variation in the transmitted color is not to be humanly
perceptible.
• the “critical flicker fusion threshold” (CFF) and the “critical color
fusion threshold” (CCF), both of which cannot resolve temporal
changes shorter than 0.01 second.
• Humans can thus perceive only this preset color that seems constant
over time, but cannot perceive the instantaneous color that varies
rapidly in time.
23. 1. What is IoT?
• Internet of things is a system of interrelated computer devices,
mechanical devices with unique identifiers and the ability to transfer
data without requiring human-computer interaction.
• The Internet of Things extends internet connectivity beyond
traditional deviceslike desktop laptop, computers, smart phones and
tablets to a diverse range of devices and everyday things that utilize
embedded technology to communicate and interact with the external
environment, all via the Internet.
24. • As the market for IoT devices grows and sensors are added to more
and more things and places, faster and heavier data transmission will
be required.
• Our current infrastructure simply cannot handle the quantity of data
that will need to be transmitted if the IoT continues to grow at
predicted rates.
25. • How we can integrate LiFi with IoT :
• Replacing all existing light fixtures with LEDs.
• Interfacing LEDs with the existing Ethernet connection.
• The transceiver is connected to all the devices, which access internet.
26. • Other Application areas of LiFi.
1. Hospital
Many treatments now involve
multiple individuals, Li-Fi systems
could be a better system to
transmit communication about the
information of patients.
Besides providing a higher speed,
light waves also have little effect
on medical instruments and human
bodies.
27. Whenever we travel through airways we
face the problem in communication
media ,because the whole airways
communication are performed on the basis
of radio waves. To overcome this
drawback on radio waves , li-fi can be
used.
2. Airlines
28. Most remotely operated underwater
vehicles (ROVs) are controlled by
wired connections. The length of
their cabling places a hard limit on
their operational range, and other
potential factors such as the cable's
weight and fragility may be
restrictive. Since light can travel
through water, Li-Fi based
communications could offer much
greater mobility.
3. Underwater application
29. In contrast to radio frequency
waves used by Wi-Fi, lights cannot
penetrate through walls and doors.
This makes it more secure and
makes it easier to control access to
a network. As long as transparent
materials like windows are
covered, access to a Li-Fi channel
is limited to devices inside the
room.
4. Security
30. •Visible Light is more safe than
RF, hence it can be used in places
where RF can't be used such as
petrochemical plants.
5. Intrinsically Safe Environment :
31. • Anywhere in industrial areas
data has to be transmitted, Li-Fi
is capable of replacing slip
rings, sliding contacts and short
cables, such as Industrial.
Ethernet. Due to the real time
capability of Li-Fi (which is
often required for automation
processes) it is also an
alternative to common industrial
Wireless LAN standards.
6. Industrial automation :
