R .V.
COLLEGE OF ENGINEERING, BENGALURU- 560 059
(Autonomous Institution Affiliated to VTU, Belagavi)
PHYSICS EXPERIENTIAL LEARNING ASSIGNMENT REPORT
2nd SEMESTER
TOPIC : Li-Fi
Submitted by
NAME: VINAY .R NAME: THEJAS B.U
SECTION: L SECTION: L
USN: 1RV18CS186 USN: 1RV18CS179
ROLL NUMBER: 15 ROLL NUMBER: 9
Submitted to:
Dr. SHIREESHA G
ASSISTANT PROFESSOR
DEPARTMENT OF PHYSICS, RVCE
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CERTIFICATE
Certified that the Assignment topic “Li-Fi” is carried out by VINAY.R and
THEJAS B.U who are bonafide students of R V College of Engineering,
Bengaluru in partial fulfilment of the award of assignment marks for the
2nd semester academic year 2018-19 in Engineering Physics Course. It is
certified that all corrections/ suggestions indicated for the internal
assessment have been incorporated in the report, and a soft copy is
deposited in the department library. The assignment report has been
approved as it satisfies the academic requirement in respect of the work
prescribed by the institution for the said course.
Marks awarded:
Cos CO1 CO2 CO3 CO4 Total
Max. Marks 03 02 01 04 10
Marks.obtd.
Signature of the Staff-in-charge
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Table of contents
Page number
i. Abstract………………………………………………………………4
ii. Introduction…………………………………………………………..4
iii. Components of a Li-Fi system………………………………….........5
iv. Working of a Li-Fi system…………………………………………...5
v. Advantages of VLC…………………………………………………..6
vi. Advantages of Li-Fi over Wi-Fi……………………………………...6
vii. Limitations of Li-Fi…………………………………………………..6
viii. Comparison between Li-Fi and other technologies…………………..7
ix. Existing Li-Fi devices and places where Li-Fi is used………….........8
x. Conclusion………………………………………………………........8
xi. References……………………………………………………….........9
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Li-Fi
Abstract - Li-fi stands for Light Fidelity. It can be thought of as light based Wi-Fi. It uses
light instead of radio waves to transmit data. Instead of Wi-Fi modems , Li-Fi would use
transceiver-fitted LED lamps that can light a room as well as transmit and receive
information. Since simple light bulbs are used , the number of access points are large. Li-Fi is
typically implemented using white LED light bulbs. This technology uses a part of the
electromagnetic spectrum that is still not utilized to a large extent- the visible light spectrum.
Visible light does not have any major harmful effects and the speed of transmission of data
through light is much faster when compared to other communication media. All these
advantages coupled with the low cost factor make Li-Fi a lucrative option .
Introduction
In the era of overcrowded (data for the first time by a German physicist
communication) world, Li-Fi is a new way Harald Hass in the TED (Technology,
of wireless communication that uses LED Entertainment, Design) Global talk on
lights to transmit data wirelessly. Visible Light Communication (VLC) in
Transmission of data is one of the most July 2011, by referring to it as “data through
important day to day activities in the fast illumination”. He used a table lamp with an
growing world. The current wireless LED bulb to transmit a video of a blooming
networks that connect us to the Internet are flower that was then projected onto a
very slow when multiple devices are screen. In simple terms, Li-Fi can be
connected. Also with the increase in the thought of as a light-based Wi-Fi i.e.
number of devices which access the instead of radio waves it uses light to
Internet, the availability of fixed bandwidth transmit data. In place of Wi-Fi modems,
makes it much more difficult to enjoy high Li-Fi would use transceivers fitted with
data transfer rates and to connect a secure LED lamps that could light a room as well
network. Radio waves are just a small part as transmit and receive information. By
of the electromagnetic spectrum available adding new and unutilized bandwidth of
for data transfer. Li-Fi has got a much visible light to the currently available radio
broader spectrum for transmission waves for data transfer, LiFi can play a
compared to conventional methods of major role in relieving the heavy loads
wireless communications that rely on radio which the current wireless system is facing.
waves. The basic ideology behind this Thus it may offer additional frequency band
technology is that the data can be of the order of 400 THz compared to that
transferred through LED light by varying available in RF communication which is
light intensities faster than the human eyes about 300 GHz. Also, as the Li-Fi uses the
can perceive. This technology uses a part of visible spectrum, it will help lessen
the electromagnetic spectrum that is still concerns that the electromagnetic waves
not greatly utilized- The Visible Spectrum, coming with Wi-Fi could adversely affect
instead of Gigahertz radio waves for data our health. By Communication through
transfer. The idea of Li-Fi was introduced visible light, Li-Fi technology has the
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possibility to change how we access the
internet, stream videos, receive emails and
much more. Security would not be an issue
as data can’t be accessed in the absence of
light. As a result, it can be used in high
security military areas where RF
communication is prone to eavesdropping.
Components of a li-fi system
The main components of a li-fi system
consist of a high brightness led which acts The Pre-requisites of a lifi system are –
as a source and a photo diode which acts as a Data conversion module which converts
the receiving element. An led is a data into bytes so that it can be represented
semiconductor device which stands for as a digital signal, it can also encrypt the
light emitting diode. It converts electrical data before conversion , a Transmitter
energy to light energy. It works on the which generates the corresponding on-off
principle of “electroluminescence”. The pattern for the leds , a Receiver module
recombination of electrons and holes lead which has a photodiode to detect the on and
to the production of light. off states of the leds, it captures this
sequence and generates the binary sequence
of the received signal , a Data interpretation
module: converts data into the original
format. if encryption was done, it also
performs decryption.
Working of a li-fi system
LEDs act as the data transmitter.Data is
encoded into light by varying the light
intensity of the LED which causes the light
to flicker ON and OFF at very high speed.
When LED is switched ‘ON’ , it represents
logical ‘1’ and when it is switched ‘OFF’, it
represents logical ‘0’.If the ON-OFF speed
of LED is fast, then more data can be
transmitted in the form of 0’s and
A photodiode is a semiconductor device 1’s.Similarly, more the number of LED
that converts light into electrical energy. It systems, more data can be transmitted. Data
works on the principle of Photoelectric receiver (also known as Li-Fi dongle)
effect. When a photon of sufficient energy consists of a photodiode. A photodiode
strikes the diode, it creates an electron-hole detects the light source and converts the
pair.This leads to the production of photo changes in its intensity into an electrical
currents. signal.When the LED flickers ON, the PD
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registers a binary 1; otherwise a binary 0. existing light fixtures. Electromagnetic
Given below is a diagram showing data interference does not impact VLC.
flow in a Li-Fi system. Currently, there are no regulations
regarding use of light . Signals cannot be
intercepted.
Advantages of Li-Fi over Wi-Fi
Wi-Fi uses radio waves. Li-Fi uses visible
light. The radio waves can penetrate
through the walls and hence data can be
misused. Since light cannot penetrate
through walls, it provides high security. Li-
Fi is cheaper when compared to Wi-Fi as it
uses fewer components and also requires
negligible additional power for data
transmission. Due to high interference and
small bandwidth, Wi-Fi fails in a area
where more people rely on it for data
transmission. On the contrary, Li-Fi can be
used in areas more people use the Internet.
Li-Fi can reach speeds beyond 1 Gbps
whereas Wi-Fi can reach speed of about
100 Mbps depending upon the number of
Advantages of visible light users.
communication
Limitations of Li-Fi
VLC uses visible light between 400THz
and 800 THz as medium, which is not The limitations of the visible light provide
dangerous for high-power applications. Li-Fi with a security advantage over Wi-Fi.
Visible light provides larger bandwidth. However, these limitations also create
Radio waves are expensive( due to disadvantages. Physical barriers such as
Spectrum charges) and less secure ( due to walls and doors limit the operational scope
interference and possible interception). X- of a Li-Fi-enabled LED lamp. The data
rays and Gamma rays have adverse effect transmitted by a Li-Fi product remains
on human health. Ultraviolet light can be confined within a close spaced because
considered for communication purposes at light cannot penetrate opaque objects and
place without people, otherwise they can be has a shorter range. A single Wi-Fi router
dangerous for human body when exposed has wider and longer range than a Li-Fi
continuously. Infrared light, due to high router. These limitations of Li-Fi also make
safety regulation, can be used only with low it not ideal for use in public Wi-Fi
power. Visible light is harmless to the networks. Current devices would not work
human body . VLC networks can be created with Li-Fi as they do not house the required
to transmit data adding optical hardware and Li-Fi is not backwards
communication devices to the sockets of compatible.
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Comparison between Li-Fi and other currently available technologies
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Existing Li-Fi devices and places stores and casinos where it can be used to
where Li-Fi is used track the real-time behaviour of the
individuals and also helps in video
Fraunhofer HHI’s has developed an optical monitoring. If Li-Fi technology is
wireless communication (OWC) implemented worldwide, every street lamp
technology known as Li-Fi and, with would be a free access point. Li-Fi can be
industry partner Sangikyo Corp., has the potential technology required to
launched the first Li-Fi device in Japan. implement 5G. Underwater ROVs
Dubbed the LED Backhaul, the device is an (Remotely Operated Vehicles) operate
LED-based optical link, initially introduced from large cables that supply their power
as a 4K/8K Video Relay that can achieve and allow them to receive signals from their
data rates between 100 and 750 megabits pilots above. But ROVs cannot explore
per second. Coutries like Russia and Japan larger areas due to the tether used. If Li-Fi
have already implemented Li-Fi on a system consisting of high-powered lamp is
smaller scale. PureLi-Fi is a company used, it would be able to explore freely.
which has a portfolio of 20 projects across They could communicate with each other
Europe. with their headlamps, process data
autonomously and can send their findings
Applications and future scope periodically back to the surface. Therefore
it can be used for endless military
Li-Fi can extend to areas where Wi-Fi
operations and also for studying, exploring
technology lacks its presence like hospitals,
and understanding of water bodies more
aircrafts and power plants where
comprehensively
electromagnetic interference is of great
concern for safety and security of people Conclusion
and equipment . In traffic signals, Li-Fi can
be used to communicate with passing Li-Fi technology thus holds the solution to
vehicles(through the LED lights of the car) various short comings of radio based
which can help in managing the traffic in a wireless communication systems such as
better manner resulting into smooth flow of shortage of bandwidth, data bottleneck,
traffic and reduction in accident numbers. high cost. It also supports green
Also, LED lights can alert drivers when environment, as it uses Visible Light
other vehicles are too close. Li-Fi can also Communication for transmission of data,
be used in petroleum or chemical plants which is harmless and available
where transmission or frequencies could be everywhere. Thus if the idea and
hazardous. Li-Fi is also environment technology of Harald Hass are put to
friendly as it does not require or emit any practical use, every LED bulb can be used
hazardous radiations. It can replace Wi-Fi as a Li-Fi hotspot for transmitting and
at educational institutions and companies so receiving wireless data. Wi-Fi is great for
that the people can make use of the internet general wireless coverage within buildings
at very high speeds. Li-Fi can relieve the ang Li-Fi is ideal for fast data transfers in a
radio spectrum of excessive capacity confined area and relieving radio
demands of cellular networks. Li-Fi can be interference issues. Therefore, the two
used in areas of high lighting such as retail technologies compliment each other
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References
1) H. Hass, Wireless data from every
light bulb, TED Global, August
2011
2) H. Hass, L. Yin, Y. Wang, C. Chen,
What is Li-Fi? IEEE J. Light
Technology 34(6) (2016) 1533-
1534
3) www.tec.gov.in
4) Ravi Prakash, Prachi Agarwal, The
New Era of Transmission and
Communication Technology: Li-Fi(
Light Fidelity) LED and TED Based
Approach, IJARCET, Volume 3,
Issue 2, February 2014
5) Anurag Sarkar, Prof. Shulabh
Agarwal, Dr. Asoke Nath, Li-Fi
Technology: Data Transmission
through Visible Light, IJARCSMS,
Volume 3, Issue 6, June 2015
6) www.wikipedia.org.lifi
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