KEMBAR78
Li-Fi Project Report | PDF
Light Fidelity (Li-Fi)
Submitted to : Department of Humanities
Paper Code : HU481
Submitted by : Shivendu Kumar (12000116044)
Shivam Kumar (12000116045)
Rohit Raj (12000116059)
Rohit Kumar (12000116060)
Rohan Vivek (12000116061)
Ritik Kumar (12000116063)
Ravishankar Jha (12000116066)
Department : CSE-1, 2nd
Year, 4th
Sem, Batch(Y)
Date of Submission : 06/04/2018
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
PREFACE
Light Fidelity (Li-Fi) is a technology that promises to give a seamless access to the
internet at an ultra-high speed. It is a technology of the future, which will make the
access to the internet easier like never before, all you need to do is to sit beneath a
light source.
Li-Fi is unique as the same light energy used for illumination may also be used for
communication. It opens up a spectrum of connectivity that is 1000 times greater
than Wi-Fi where Radio Frequency technologies are running out of spectrum.
Li-Fi uses LEDs and photo detectors for data transmission which makes it cheaper
than current RF technologies and also provides better speed. It also ensures better
security than currently popular Wi-Fi as light cannot pass through walls so no data
can be accessed from outside.
The technology has ability to overtake current data transmission technologies in
near future. More and more IoT devices will be able to connect to each other and
underwater communication will also be easier than it was never before with RF
technology.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
LETTER OF TRANSMITTAL
This is to certify that the following students Shivendu Kumar (12000116044),
Shivam Kumar (12000116045), Rohit Raj (12000116059), Rohit Kumar
(12000116060), Rohan Vivek (12000116061), Ritik Kumar (12000116063),
Ravishankar Jha(12000116066) of C.S.E-1, 2nd
year, 4th
Sem, Batch (Y) have
successfully completed their project “LIGHT FIDELITY” on the given time
under my supervision and guidance in requirements of the curriculum of of 4th
sem.
Dated: …………… .………………………
Prof. Dinesh Pradhan
(Asst. Professor, Dept. of CSE, BCREC, DGP)
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
ACKNOWLEDGEMENT
We are really grateful because we managed to complete our project within the time
given by our faculty of Humanities Department.
We would like to express our sincere gratitude to our mentor Prof. Dinesh Pradhan
for his vital support, guidance and encouragement without which this project would
had not come forth.
We would also like to express our sincere gratitude to the Department of
Humanities for providing us with an opportunity to do the project.
This project couldn’t be completed without the co-operation of our faculty of
humanities department Prof. Debadrita Sen.
Shivendu Kumar (12000116044)
Shivam Kumar (12000116045)
Rohit Raj (12000116059)
Rohit Kumar (12000116060)
Rohan Vivek (12000116061)
Ritik Kumar (12000116063)
Ravishankar Jha (12000116066)
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
CONTENTS
Sl. No. Name Of Topic Page No.
1. Introduction 1
2. Architechture 2
3. How Li-Fi Works? 6
4. Why Visible Light Communication? 9
5. Features and Benefits 10
6. Comparision with Wi-Fi 13
7. Disadvantages 15
8. Applications 16
9. Future Possibilities 20
10. Conclusion 21
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
LIST OF ILLUSTRATIONS
Sl. No. Name of Illustration Figure No. Page
No.
1. Architechture of Li-Fi Technology Fig 2.1 2
2. Design of a Li-Fi enabled bulb Fig 2.2 4
3. Data Transmission in Li-Fi Fig 3.1 6
4. Comparision in bandwidth of Radio
frequencies and Light spectrum
Fig 5.1 10
5. Comparision between Li-Fi and Wi-Fi on
various parameters
Table 6.1 14
6. Smart Urban Lighting Fig 8.1 16
7. Mobile Connectivity using Cellular, Wi-Fi
and Li-Fi Networks
Fig 8.2 17
8. Use of Li-Fi in Hospitals Fig 8.3 17
9. Use of Li-Fi in Undewater communications Fig 8.4 18
10. Use of Li-Fi in Vehicles Fig 8.5 19
11. Use of Li-Fi in Toys Fig 8.6 19
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
ABSTRACT
Whether you’re using wireless internet in a coffee shop, stealing it from the guy
next door, or competing for bandwidth at a conference, you’ve probably gotten
frustrated with the slow speeds you face when more than one device is tapped into
the network. As more and more people and their many devices access wireless
internet, clogged airwaves are going to make it increasingly difficult to latch onto a
reliable signal.
But radio waves are just one part of the spectrum that can carry our data. What if
we could use other waves to surf the internet? One German physicist Dr. Harald
Haas, has come up with a solution he calls “Data Through Illumination”- taking the
fiber out of fiber optics by sending data through an LED light bulb that varies in
intensity faster than the human eye can follow. It’s the same idea behind infrared
remote controls, but far more powerful.
Li-Fi provides better bandwidth, efficiency, connectivity and security than Wi-Fi
and has already achieved high speeds larger than 1 Gbps under the laboratory
conditions. By leveraging the low-cost nature of LEDs and lighting units, there are
lots of opportunities to exploit this medium.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
HISTORY
Harald Haas, a professor at the University of Edinburgh who began his research in
the field in 2004, gave a debut demonstration of what he called a Li-Fi prototype at
the TEDGlobal conference in Edinburgh on 12th July 2011. He used a table lamp
with an LED bulb to transmit a video of clouds onto a laptop connected to the
prototype.
During the event he periodically blocked the light from lamp to prove that the lamp
was indeed the source of incoming data. At TEDGlobal, Haas demonstrated a data
rate of transmission of around 10Mbps -- comparable to a fairly good UK
broadband connection. Two months later he achieved 123Mbps.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
1
1. INTRODUCTION
In simple terms, Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses
light instead of radio waves to transmit information. And 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,
there can technically be any number of access points.
This technology uses a part of the electromagnetic spectrum that is still not
greatly utilized- The Visible Light Spectrum. Light is in fact very much part of
our lives for millions and millions of years and does not have any major ill
effect. Moreover there is 10,000 times more space available in this spectrum and
just counting on the bulbs in use, it also multiplies to 10,000 times more
availability as an infrastructure, globally.
It is possible to encode data in the light by varying the rate at which the LEDs
flicker on and off to give different strings of 1s and 0s. The LED intensity is
modulated so rapidly that human eyes cannot notice, so the output appears
constant.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
2
2. ARCHITECTURE
The Li-Fi architecture contains various devices such as LED bulbs, mobile
devices and the photo detector which receives the binary data over light. The
binary data is captured by few light receptors which are installed on all types of
connecting devices such as computer tablets, phones, televisions, or appliances.
Fig 2.1 Architechture of Li-Fi Technology
The various components of a basic Li-Fi system are as follows:
2.1. Server
A server is a computer program that provides services to other computer
programs (and their users) in the same or other computers. The computer that a
server program runs in is also frequently referred to as a server. That machine
may be a dedicated server or used for other purposes as well.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
3
2.2. Internet
The Internet, sometimes called simply "the Net", is a worldwide system of
computer networks - a network of networks in which users at any one computer
can, if they have permission, get information from any other computer (and
sometimes talk directly to users at other computers).
2.3. Lamp Driver
Lamp Driver is a small integrated circuit designed to supply the current required
by a lamp. It manages the incoming voltage and current to the voltage and
current level requirements of the lamp.
2.4. Lead Lamp
A high brightness white LED acts as a communication source. It is guided by
the PCB and powered by PA and is enclosed in an aluminium enclosure. An
LED lamp is a light-emitting diode (LED) product which is assembled into a
lamp (or light bulb) for use in lighting fixtures LED lamps have a lifespan and
electrical efficiency which are several times greater than incandescent lamps
and are significantly more efficient than most fluorescent lamps.
2.4.1. Design of the Bulb
The first part is the Ethernet Cable Slot. This is the slot where the LAN cable
will be connected to connect the Bulb with the Internet.
The second part is the Real Time Clock and Battery Pack. The function of a
clock is mainly to generate pulse, and so is the function of the Real Time Clock
in the Bulb. It generates pulses as per the requirement of the data.
The third and the most important part is the Microcontroller & Circuit. The
Microcontroller part controls all the functionalities of the Bulb. Its main
functions are to control the clock timing, to control which data is to be sent and
to whom it is to be sent, and to control the intensity of light.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
4
The Circuit part mainly comprises of the modulating circuit, which is
responsible for the modulation of the illuminating light as per the requirement,
and again it is controlled by the Microcontroller.
Fig 2.2 Design of a Li-Fi enabled bulb
The Ring part is nothing but an interface between the above explained parts and
the LED part.
And the last part, the Light-Emitting Diode (LED), which illuminates the room
with light and data. In other words, it transmits the data through light.
2.5. RF Power Amplifier Circuit (PA)
A radio frequency power amplifier (RF power amplifier) is a type of electronic
amplifier that converts a low-power radio-frequency signal into a higher power
signal. Typically, RF power amplifiers drive the antenna of a transmitter.
Design goals often include gain, power output, bandwidth, power efficiency,
linearity (low signal compression at rated output), input and output impedance
matching, and heat dissipation.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
5
2.6. Photo Detector
Photo Detectors or Photo Sensors are sensors of light or other electromagnetic
energy. A photo detector has a p–n junction that converts light photons into
current. The junction is covered by an illumination window, usually having an
anti-reflective coating. The absorbed photons make electron-hole pairs in the
depletion region. Photodiodes and photo transistors are a few examples of photo
detectors. Solar cells convert some of the light energy absorbed into electrical
energy.
2.7. Monitor
The term "monitor" is often used synonymously with "computer screen" or
"display". The monitor displays the computer's user interface and open
programs, allowing the user to interact with the computer, typically using the
keyboard and mouse.
Fig. 2.1 shows the basic architecture of a Li-Fi system. At the transmitter’s end,
the Server provides all the Internet contents to the Lamp Driver. The Lamp
driver manages the voltage and current levels of the LED as per the
requirements of the data to be transmitted. Then this data is modulated with the
LED’s light by the use of different modulation techniques and is illuminated by
switching on the LED. At the receiver’s end, this illuminated data is captured by
the Photo Detector, amplified by the Power Amplifier, and at last displayed on
the Monitor.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
6
3. HOW Li-Fi WORKS?
The working of Li-Fi is based on a very simple concept, when the LED is on, a
digital 1 is transmitted, and when it is off, a digital 0 is transmitted. The LEDs
can be switched on and off very quickly, which gives nice opportunities for
transmitting data.
The Li-Fi technology is based on the Visible Light Communication which uses
the visible light for data communication. In VLC, we use a source of
illumination which can not only produce illumination but also send information
using the same light. So we can say that VLC is illumination along with
communication.
Fig 3.1 Data Transmission in Li-Fi
Li-Fi is a fast and cheap optical version of Wi-Fi, the technology of which is
based on Visible Light Communication (VLC). VLC is a data communication
medium, which uses visible light between 400 THz (780 nm) and 800 THz (375
nm) as optical carrier for data transmission and illumination. It uses fast pulses
of light to transmit information wirelessly. The main components of this
communication system are:
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
7
i. a high brightness white LED, which acts as a communication source and
ii. a silicon photodiode which shows good response to visible wavelength
region serving as the receiving element.
LED can be switched on and off to generate digital strings of 1s and 0s. Data
can be encoded in the light to generate a new data stream by varying the
flickering rate of the LED. To be clearer, by modulating the LED light with the
data signal, the LED illumination can be used as a communication source. As
the flickering rate is so fast, the LED output appears constant to the human eye.
A data rate of greater than 100 Mbps is possible by using high speed LEDs with
appropriate multiplexing techniques. VLC data rate can be increased by parallel
data transmission using LED arrays where each LED transmits a different data
stream. There are reasons to prefer LED as the light source in VLC while a lot
of other illumination devices like fluorescent lamp, incandescent bulb etc. are
available, and the prime reason among then is its high flickering rates.
3.1. Modulation Techniques used in Li-Fi
Some of the techniques used for modulating the LED light with data signal are:
3.1.1. OFDM
Orthogonal frequency-division multiplexing (OFDM) is a method of encoding
digital data on multiple carrier frequencies. OFDM is a frequency-division
multiplexing (FDM) scheme used as a digital multi-carrier modulation method.
A large number of closely spaced orthogonal sub-carrier signals are used to
carry data on several parallel data streams or channels. Each sub-carrier is
modulated with a conventional modulation scheme (such as quadrature
amplitude modulation or phase shift keying) at a low symbol rate, maintaining
total data rates similar to conventional single-carrier modulation schemes in the
same bandwidth.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
8
3.1.2. OOK
On-off keying (OOK) denotes the simplest form of amplitude-shift keying
(ASK) modulation that represents digital data as the presence or absence of a
carrier wave. In its simplest form, the presence of a carrier for a specific
duration represents a binary one, while its absence for the same duration
represents a binary zero. Some more sophisticated schemes vary these durations
to convey additional information. It is analogous to unipolar encoding line code.
It is very easy to generate and decode but is not very optimal in terms of
illumination control and data throughput.
3.1.3. PWM
Pulse-width modulation (PWM) is a technique used to encode a message into a
pulsing signal. Although this modulation technique can be used to encode
information for transmission, its main use is to allow the control of the power
supplied to electrical devices, especially to inertial loads such as motors. Pulse
Width Modulation transmits the data by encoding the data into the duration of
the pulses. More than one bit of data can be conveyed within each pulse.
3.1.4. PPM
Pulse-position modulation (PPM) is a form of signal modulation in which M
message bits are encoded by transmitting a single pulse in one of possible
required time-shifts. This is repeated every T seconds, such that the transmitted
bit rate is bits per second. It is primarily useful for optical communications
systems, where there tends to be little or no multipath interference.
3.1.5. SIM-OFDM
Sub-carrier Index Modulation OFDM is a technique which adds an additional
dimension to the two dimensional amplitude/phase modulation technique i.e.,
Amplitude Shift Keying (ASK) and Quadrature Amplitude Modulation (QAM).
SIM uses the subcarrier index to convey information to the receiver. Unlike the
traditional OFDM technique, the SIM-OFDM technique splits the serial bit
stream into two bit sub-streams of the same length.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
9
4. WHY VISIBLE LIGHT COMMUNICATION?
The frequency spectrum that is available to us in the atmosphere consists of
many wave regions like X-rays, gamma rays, ultraviolet region, infrared region,
visible light rays, radio waves, etc. Anyone of the above waves can be used in
the upcoming communication technologies but why the Visible Light part is
chosen? The reason behind this is the easy availability and lesser harmful effects
that occur due to these rays of light. VLC uses the visible light between 400
THz (780 nm) and 800 THz (375 nm) as medium which are less dangerous for
high-power applications and also humans can easily perceive it and protect
themselves from the harmful effects whereas the other wave regions have
following disadvantages:
 Radio waves are expensive (due to spectrum charges) and less secure
(due to interference and possible interception etc.)
 Gamma rays are harmful because it could be dangerous dealing with it,
by the human beings due to their proven adverse effects on human
health.
 X-rays have health issues, similar to the Gamma Rays.
 Ultraviolet light can be considered for communication technology
purposes at place without people, otherwise they can also be dangerous
for the human body when exposed continuously.
 Infrared, due to high safety regulation, can only be used with low power.
Hence the Visible light portion (from red to blue) of the electromagnetic
spectrum does not cause any harm to the people as visible rays are safe to use,
provide larger bandwidth and also have a promising future in the
communication field.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
10
5. FEATURES AND BENEFITS
Li-Fi features include benefits to the capacity, energy efficiency, safety and
security of a wireless system with a number of key benefits over Wi-Fi but is
inherently a complementary technology.
5.1. Bandwidth
As we know, Li-Fi uses the visible light spectrum (400 THz to 800 THz), and
this spectrum is plentiful (10,000 times more than RF spectrum), unlicensed and
free to use, providing us a much greater bandwidth than Wi-Fi or any other
wireless communication technology.
Fig 5.1 Comparision in bandwidth of Radio frequencies and Light spectrum
5.2 Data density
Li-Fi has a considerably high data density. The traditional radio frequencies,
used in the wireless communication tend to spread out and cause interference.
But this is not the case with visible light. Visible light is having the capability to
be contained in a tight illumination area, which ultimately increases data
density. A higher data density means more number of data packets transmitted
per unit time.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
11
5.3. High Speed
As discussed earlier, the Li-Fi is having a considerably high bandwidth, and a
high data density. Moreover, the intensity of LED is also much higher. All these
factors lead to the transmission of considerably higher amount of data per unit
time, which ultimately increases the data transmission speed to a great extent.
5.4. Planning
As the Li-Fi technology is based on the illumination infrastructure, a good
signal strength can literally be seen. Also the intensity variation and switching
of LED is fast enough that it can’t be seen by human eyes. This makes the
capacity planning much easier.
5.5. Low Cost
Li-Fi mainly uses LEDs and Photo Detectors for the transmission and reception
of data, which makes it much cheaper than the current RF based wireless
technologies, which are composed with numerous components. Also, the data
transmission speed is 10-100 times higher in Li-Fi, which makes it much more
cost efficient.
5.6. Efficiency
LED is itself power efficient. And all the other components used in Li-Fi are
minor power consumers. This makes Li-Fi a greatly power efficient technology.
Moreover, we don’t need additional power for the Li-Fi, as it will be using the
same power used for the illumination of a room.
5.7. Environment
Transmission and propagation of RF in water is extremely difficult, which
makes underwater communication impossible. But that’s not the case with Li-
Fi, as it uses the visible spectrum of light; and the transmission and propagation
of visible light in water is very easy.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
12
5.8. Safety
Until now, there’s no known safety issues with Li-Fi, as it uses visible light.
And visible light can never be harmful for anyone, considering the fact that the
current RF technologies emit harmful radiation. The transmission of light avoids
the use of radio frequencies which can dangerously interfere with electronic
circuitry in certain environments.
5.9. Security
For getting access to the Li-Fi signal, it is the prime need to keep the signal
receiver directly in the illuminated area. In other words, no signal without direct
light. This property prevents the Li-Fi network from the outside intruders,
hackers and unwanted users.
5.10. Control
Data may be directed from one device to another and the user can see where the
data is going; there is no need for additional security such as pairing for RF
interconnections such as Bluetooth. This gives the user a great control over what
to send and where to send, and also prevents data leakage.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
13
6. COMPARISION WITH Wi-Fi
There are several advantages of Li-Fi over Wi-Fi:
 Li-Fi uses light rather than radio frequency signals so are intolerant to
disturbances.
 VLC could be used safely in aircraft without affecting airlines signals.
 Integrated into medical devices and in hospitals as this technology
doesn’t deal with radio waves, so it can easily be used in all such places
where Bluetooth, infrared, Wi-Fi and internet are broadly in use.
 Under water in sea Wi-Fi does not work at all but light can be used and
hence undersea explorations are good to go now with much ease.
 There are billions of bulbs worldwide which just need to be replaced with
LED’s to transmit data.
 Security is a side benefit of using light for data transfer as it does not
penetrate through walls.
 On highways for traffic control applications like where Cars can have
LED based headlights, LED based backlights, and they can communicate
with each other and prevent accidents.
 Using this Technology worldwide every street lamp would be a free data
access point.
 The issues of the shortage of radio frequency bandwidth may be sorted
out by Li-Fi.
The table on the next page shows the comparison of Li-Fi with Wi-Fi on various
parameters.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
14
Table 6.1 Comparison between Li-Fi and Wi-Fi on various parameters
Parameter Li-Fi Wi-Fi
Speed *** **
Data Density *** *
Security *** **
Reliability *** **
Ecological Impact * **
Device-to-device Connectivity *** ***
Obstacle Interference *** *
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
15
7. DISADVANTAGES
Every good thing comes with a bad side. For example, in case of LiFi, internet
cannot be used without a light source. This could limit the locations and
situations in which Li-Fi could be used. Similarly, there are few more
disadvantages, which should be taken care of.
 Because it uses visible light, and light cannot penetrate walls, the signal's
range is limited by physical barriers.
 Other sources of light may interfere with the signal. One of the biggest
potential drawbacks is the interception of signals outdoors. Sunlight will
interfere the signals, resulting in interrupted Internet.
 A whole new infrastructure for Li-Fi would need to be constructed.
 Cost is also another factor. As each LED bulb requires a module attached
to it to convert incoming data into flickers, it could be expensive to
retrofit whole buildings with such equipment.
 Computers or mobile devices will also need to be fitted with sensors that
can read the light signals and convert them into data. The sensors are
currently about the size of a smartphone and thus not very convenient for
mobile users.
 A device has to be within the line of sight of the light source, unlike Wi-
Fi which can penetrate most walls.
 The problem of how the receiver will transmit back to the transmitter still
persists.
 We become dependent on the light source for internet access. If the light
source malfunctions, we lose access to the internet.
But considering the fact that research works are still going on, there are bright
chances that most of these problems will soon be eradicated in the near future.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
16
8. APPLICATIONS
The dramatic growth in the use of LEDs (Light Emitting Diodes) for lighting
provides the opportunity to incorporate Li-Fi technology into a plethora of LED
environments.
Li-Fi is particularly suitable for many popular internet “content consumption”
applications such as video and audio downloads, live streaming, etc. These
applications place heavy demands on the downlink bandwidth, but require
minimal uplink capacity. In this way, the majority of the internet traffic is off-
loaded from existing RF channels, thus also extending cellular and Wi-Fi
capacities.
There are many applications for Li-Fi. These include:
8.1. RF Spectrum Relief
Excess capacity demands of cellular networks can be off-loaded to Li-Fi
networks where available. This is especially effective on the downlink where
bottlenecks tend to occur.
8.2. Smart Lighting
Any private or public lighting including street lamps can be used to provide Li-
Fi hotspots and the same communications and sensor infrastructure can be used
to monitor and control lighting and data.
Fig 8.1 Smart Urban Lighting
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
17
8.3. Mobile Connectivity
Laptops, smart phones, tablets and other mobile devices can interconnect
directly using Li-Fi. Short range links give very high data rates and also
provides security.
Fig 8.2 Mobile Connectivity using Cellular, Wi-Fi and Li-Fi Networks
8.4. Hazardous Environments
Li-Fi provides a safe alternative to electromagnetic interference from radio
frequency communications in environments such as mines and petrochemical
plants.
8.5. Hospital & Healthcare
Li-Fi emits no electromagnetic interference and so does not interfere with
medical instruments, nor is it interfered with by MRI scanners.
Fig 8.3 Use of Li-Fi in Hospitals
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
18
8.6. Aviation
Li-Fi can be used to reduce weight and cabling and add flexibility to seating
layouts in aircraft passenger cabins where LED lights are already deployed. In-
flight entertainment (IFE) systems can also be supported and integrated with
passengers’ own mobile devices.
8.7. Underwater Communications
Due to strong signal absorption in water, RF use is impractical. Acoustic waves
have extremely low bandwidth and disturb marine life. Li-Fi provides a solution
for short-range communications.
Fig 8.4 Use of Li-Fi in Undewater communications
8.8. Vehicles & Transportation
LED headlights and tail-lights are being introduced. Street lamps, signage and
traffic signals are also moving to LED. This can be used for vehicle-to-vehicle
and vehicle-to-roadside communications. This can be applied for road safety
and traffic management.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
19
Fig 8.5 Use of Li-Fi in Vehicles
8.9. RF Avoidance
Some people claim they are hypersensitive to radio frequencies and are looking
for an alternative. Li-Fi is a good solution to this problem.
8.10. Location Based Services (LBS)
Highly accurate location-specific information services such as advertising and
navigation that enables the recipient to receive appropriate, pertinent
information in a timely manner and location.
8.11. Toys
Many toys incorporate LED lights and these can be used to enable extremely
low-cost communication between interactive toys.
Fig 8.6 Use of Li-Fi in Toys
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
20
9. FUTURE POSSIBILITIES
Li-Fi is purely a technology of future. It is having a potential to take over all the
internet market on its own. The main points to be noted here are as follows:
 With the advancement of Li-Fi technology, it will become more portable,
taking its rightful places in our phones and laptops.
 It will give the field of IoT a considerable boost as more and more
number of devices will be able to connect and interact with each other
through Li-Fi.
 We will also be able to access the internet in places like Hospitals and
Airplanes where traditional network systems can never be used.
 Underwater communication will become much easier with the use of Li-
Fi.
 In future, it may be possible that we will be having an internet with a
speed of multi gigabits per second.
 With Li-Fi, we will also be moving towards a much more secured
network, which will be safeguarding us from unwanted hackers.
 Depletion of Environment due to increased use of radio frequencies will
also decrease, as the Li-Fi technology uses the visible spectrum of light
to transmit data.
 Installation will also not be an issue with Li-Fi.
 Multiuser support of Li-Fi will ensure that every individual is getting a
high speed of internet.
And these points will probably keep increasing as we will be moving forward
towards the future.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
21
10.CONCLUSION
Although there’s still a long way to go to make this technology a commercial
success, it promises a great potential in the field of wireless internet. A
significant number of researchers and companies are currently working on this
concept, which promises to solve the problem of lack of radio spectrum, space
and low internet connection speed. By deployment of this technology, we can
migrate to greener, cleaner, safer communication networks. The very concept of
Li-Fi promises to solve issues such as, shortage of radio-frequency bandwidth
and eliminates the disadvantages of Radio communication technologies. Li-Fi is
the upcoming and growing technology acting as catalyst for various other
developing and new inventions/technologies. Therefore, there is certainty of
development of future applications of the Li-Fi which can be extended to
different platforms and various walks of human life.
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
APPENDIX
ASK Amplitude-Shift Keying
FDM Frequency Division Multiplexing
Gbps Gigabits per second
IFE In-flight entertainment
IoT Internet of Things
LAN Local Area Network
LBS Location Based Services
LED Light-emitting Diode
Li-Fi Light Fidelity
Mbps Megabits per second
MBps Megabytes per second
QAM Quadrature Amplitude Modulation
OFDM Orthogonal Frequency Division Multiplexing
OOK On-off Keying
PA Power Amplifier
PCB Printed Circuit Board
PPM Pulse-position Modulation
PWM Pulse-width modulation
RF Radio Frequency
SIM-OFDM Sub-carrier Index Modulation OFDM
THz TeraHertz
UK United Kingdom
VLC Visible Light Communication
Wi-Fi Wireless Fidelity
CSE-1(Y), 2nd
Yr,4th
Sem/Li-Fi/06.04.2018
REFERENCES
https://en.wikipedia.org/wiki/Li-Fi
Date and Time of visit: 08/03/2018 19:00
https://purelifi.com/technology/#what-is-lifi
Date and Time of visit: 09/03/2018 22:20
http://tec.gov.in/pdf/Studypaper/lifi%20study%20paper%20-%20approved.pdf
Date and Time of visit: 10/03/2018 20:32

Li-Fi Project Report

  • 1.
    Light Fidelity (Li-Fi) Submittedto : Department of Humanities Paper Code : HU481 Submitted by : Shivendu Kumar (12000116044) Shivam Kumar (12000116045) Rohit Raj (12000116059) Rohit Kumar (12000116060) Rohan Vivek (12000116061) Ritik Kumar (12000116063) Ravishankar Jha (12000116066) Department : CSE-1, 2nd Year, 4th Sem, Batch(Y) Date of Submission : 06/04/2018
  • 2.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 PREFACE Light Fidelity(Li-Fi) is a technology that promises to give a seamless access to the internet at an ultra-high speed. It is a technology of the future, which will make the access to the internet easier like never before, all you need to do is to sit beneath a light source. Li-Fi is unique as the same light energy used for illumination may also be used for communication. It opens up a spectrum of connectivity that is 1000 times greater than Wi-Fi where Radio Frequency technologies are running out of spectrum. Li-Fi uses LEDs and photo detectors for data transmission which makes it cheaper than current RF technologies and also provides better speed. It also ensures better security than currently popular Wi-Fi as light cannot pass through walls so no data can be accessed from outside. The technology has ability to overtake current data transmission technologies in near future. More and more IoT devices will be able to connect to each other and underwater communication will also be easier than it was never before with RF technology.
  • 3.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 LETTER OFTRANSMITTAL This is to certify that the following students Shivendu Kumar (12000116044), Shivam Kumar (12000116045), Rohit Raj (12000116059), Rohit Kumar (12000116060), Rohan Vivek (12000116061), Ritik Kumar (12000116063), Ravishankar Jha(12000116066) of C.S.E-1, 2nd year, 4th Sem, Batch (Y) have successfully completed their project “LIGHT FIDELITY” on the given time under my supervision and guidance in requirements of the curriculum of of 4th sem. Dated: …………… .……………………… Prof. Dinesh Pradhan (Asst. Professor, Dept. of CSE, BCREC, DGP)
  • 4.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 ACKNOWLEDGEMENT We arereally grateful because we managed to complete our project within the time given by our faculty of Humanities Department. We would like to express our sincere gratitude to our mentor Prof. Dinesh Pradhan for his vital support, guidance and encouragement without which this project would had not come forth. We would also like to express our sincere gratitude to the Department of Humanities for providing us with an opportunity to do the project. This project couldn’t be completed without the co-operation of our faculty of humanities department Prof. Debadrita Sen. Shivendu Kumar (12000116044) Shivam Kumar (12000116045) Rohit Raj (12000116059) Rohit Kumar (12000116060) Rohan Vivek (12000116061) Ritik Kumar (12000116063) Ravishankar Jha (12000116066)
  • 5.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 CONTENTS Sl. No.Name Of Topic Page No. 1. Introduction 1 2. Architechture 2 3. How Li-Fi Works? 6 4. Why Visible Light Communication? 9 5. Features and Benefits 10 6. Comparision with Wi-Fi 13 7. Disadvantages 15 8. Applications 16 9. Future Possibilities 20 10. Conclusion 21
  • 6.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 LIST OFILLUSTRATIONS Sl. No. Name of Illustration Figure No. Page No. 1. Architechture of Li-Fi Technology Fig 2.1 2 2. Design of a Li-Fi enabled bulb Fig 2.2 4 3. Data Transmission in Li-Fi Fig 3.1 6 4. Comparision in bandwidth of Radio frequencies and Light spectrum Fig 5.1 10 5. Comparision between Li-Fi and Wi-Fi on various parameters Table 6.1 14 6. Smart Urban Lighting Fig 8.1 16 7. Mobile Connectivity using Cellular, Wi-Fi and Li-Fi Networks Fig 8.2 17 8. Use of Li-Fi in Hospitals Fig 8.3 17 9. Use of Li-Fi in Undewater communications Fig 8.4 18 10. Use of Li-Fi in Vehicles Fig 8.5 19 11. Use of Li-Fi in Toys Fig 8.6 19
  • 7.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 ABSTRACT Whether you’reusing wireless internet in a coffee shop, stealing it from the guy next door, or competing for bandwidth at a conference, you’ve probably gotten frustrated with the slow speeds you face when more than one device is tapped into the network. As more and more people and their many devices access wireless internet, clogged airwaves are going to make it increasingly difficult to latch onto a reliable signal. But radio waves are just one part of the spectrum that can carry our data. What if we could use other waves to surf the internet? One German physicist Dr. Harald Haas, has come up with a solution he calls “Data Through Illumination”- taking the fiber out of fiber optics by sending data through an LED light bulb that varies in intensity faster than the human eye can follow. It’s the same idea behind infrared remote controls, but far more powerful. Li-Fi provides better bandwidth, efficiency, connectivity and security than Wi-Fi and has already achieved high speeds larger than 1 Gbps under the laboratory conditions. By leveraging the low-cost nature of LEDs and lighting units, there are lots of opportunities to exploit this medium.
  • 8.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 HISTORY Harald Haas,a professor at the University of Edinburgh who began his research in the field in 2004, gave a debut demonstration of what he called a Li-Fi prototype at the TEDGlobal conference in Edinburgh on 12th July 2011. He used a table lamp with an LED bulb to transmit a video of clouds onto a laptop connected to the prototype. During the event he periodically blocked the light from lamp to prove that the lamp was indeed the source of incoming data. At TEDGlobal, Haas demonstrated a data rate of transmission of around 10Mbps -- comparable to a fairly good UK broadband connection. Two months later he achieved 123Mbps.
  • 9.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 1 1. INTRODUCTION Insimple terms, Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light instead of radio waves to transmit information. And 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, there can technically be any number of access points. This technology uses a part of the electromagnetic spectrum that is still not greatly utilized- The Visible Light Spectrum. Light is in fact very much part of our lives for millions and millions of years and does not have any major ill effect. Moreover there is 10,000 times more space available in this spectrum and just counting on the bulbs in use, it also multiplies to 10,000 times more availability as an infrastructure, globally. It is possible to encode data in the light by varying the rate at which the LEDs flicker on and off to give different strings of 1s and 0s. The LED intensity is modulated so rapidly that human eyes cannot notice, so the output appears constant.
  • 10.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 2 2. ARCHITECTURE TheLi-Fi architecture contains various devices such as LED bulbs, mobile devices and the photo detector which receives the binary data over light. The binary data is captured by few light receptors which are installed on all types of connecting devices such as computer tablets, phones, televisions, or appliances. Fig 2.1 Architechture of Li-Fi Technology The various components of a basic Li-Fi system are as follows: 2.1. Server A server is a computer program that provides services to other computer programs (and their users) in the same or other computers. The computer that a server program runs in is also frequently referred to as a server. That machine may be a dedicated server or used for other purposes as well.
  • 11.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 3 2.2. Internet TheInternet, sometimes called simply "the Net", is a worldwide system of computer networks - a network of networks in which users at any one computer can, if they have permission, get information from any other computer (and sometimes talk directly to users at other computers). 2.3. Lamp Driver Lamp Driver is a small integrated circuit designed to supply the current required by a lamp. It manages the incoming voltage and current to the voltage and current level requirements of the lamp. 2.4. Lead Lamp A high brightness white LED acts as a communication source. It is guided by the PCB and powered by PA and is enclosed in an aluminium enclosure. An LED lamp is a light-emitting diode (LED) product which is assembled into a lamp (or light bulb) for use in lighting fixtures LED lamps have a lifespan and electrical efficiency which are several times greater than incandescent lamps and are significantly more efficient than most fluorescent lamps. 2.4.1. Design of the Bulb The first part is the Ethernet Cable Slot. This is the slot where the LAN cable will be connected to connect the Bulb with the Internet. The second part is the Real Time Clock and Battery Pack. The function of a clock is mainly to generate pulse, and so is the function of the Real Time Clock in the Bulb. It generates pulses as per the requirement of the data. The third and the most important part is the Microcontroller & Circuit. The Microcontroller part controls all the functionalities of the Bulb. Its main functions are to control the clock timing, to control which data is to be sent and to whom it is to be sent, and to control the intensity of light.
  • 12.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 4 The Circuitpart mainly comprises of the modulating circuit, which is responsible for the modulation of the illuminating light as per the requirement, and again it is controlled by the Microcontroller. Fig 2.2 Design of a Li-Fi enabled bulb The Ring part is nothing but an interface between the above explained parts and the LED part. And the last part, the Light-Emitting Diode (LED), which illuminates the room with light and data. In other words, it transmits the data through light. 2.5. RF Power Amplifier Circuit (PA) A radio frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency signal into a higher power signal. Typically, RF power amplifiers drive the antenna of a transmitter. Design goals often include gain, power output, bandwidth, power efficiency, linearity (low signal compression at rated output), input and output impedance matching, and heat dissipation.
  • 13.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 5 2.6. PhotoDetector Photo Detectors or Photo Sensors are sensors of light or other electromagnetic energy. A photo detector has a p–n junction that converts light photons into current. The junction is covered by an illumination window, usually having an anti-reflective coating. The absorbed photons make electron-hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy. 2.7. Monitor The term "monitor" is often used synonymously with "computer screen" or "display". The monitor displays the computer's user interface and open programs, allowing the user to interact with the computer, typically using the keyboard and mouse. Fig. 2.1 shows the basic architecture of a Li-Fi system. At the transmitter’s end, the Server provides all the Internet contents to the Lamp Driver. The Lamp driver manages the voltage and current levels of the LED as per the requirements of the data to be transmitted. Then this data is modulated with the LED’s light by the use of different modulation techniques and is illuminated by switching on the LED. At the receiver’s end, this illuminated data is captured by the Photo Detector, amplified by the Power Amplifier, and at last displayed on the Monitor.
  • 14.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 6 3. HOWLi-Fi WORKS? The working of Li-Fi is based on a very simple concept, when the LED is on, a digital 1 is transmitted, and when it is off, a digital 0 is transmitted. The LEDs can be switched on and off very quickly, which gives nice opportunities for transmitting data. The Li-Fi technology is based on the Visible Light Communication which uses the visible light for data communication. In VLC, we use a source of illumination which can not only produce illumination but also send information using the same light. So we can say that VLC is illumination along with communication. Fig 3.1 Data Transmission in Li-Fi Li-Fi is a fast and cheap optical version of Wi-Fi, the technology of which is based on Visible Light Communication (VLC). VLC is a data communication medium, which uses visible light between 400 THz (780 nm) and 800 THz (375 nm) as optical carrier for data transmission and illumination. It uses fast pulses of light to transmit information wirelessly. The main components of this communication system are:
  • 15.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 7 i. ahigh brightness white LED, which acts as a communication source and ii. a silicon photodiode which shows good response to visible wavelength region serving as the receiving element. LED can be switched on and off to generate digital strings of 1s and 0s. Data can be encoded in the light to generate a new data stream by varying the flickering rate of the LED. To be clearer, by modulating the LED light with the data signal, the LED illumination can be used as a communication source. As the flickering rate is so fast, the LED output appears constant to the human eye. A data rate of greater than 100 Mbps is possible by using high speed LEDs with appropriate multiplexing techniques. VLC data rate can be increased by parallel data transmission using LED arrays where each LED transmits a different data stream. There are reasons to prefer LED as the light source in VLC while a lot of other illumination devices like fluorescent lamp, incandescent bulb etc. are available, and the prime reason among then is its high flickering rates. 3.1. Modulation Techniques used in Li-Fi Some of the techniques used for modulating the LED light with data signal are: 3.1.1. OFDM Orthogonal frequency-division multiplexing (OFDM) is a method of encoding digital data on multiple carrier frequencies. OFDM is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method. A large number of closely spaced orthogonal sub-carrier signals are used to carry data on several parallel data streams or channels. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase shift keying) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth.
  • 16.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 8 3.1.2. OOK On-offkeying (OOK) denotes the simplest form of amplitude-shift keying (ASK) modulation that represents digital data as the presence or absence of a carrier wave. In its simplest form, the presence of a carrier for a specific duration represents a binary one, while its absence for the same duration represents a binary zero. Some more sophisticated schemes vary these durations to convey additional information. It is analogous to unipolar encoding line code. It is very easy to generate and decode but is not very optimal in terms of illumination control and data throughput. 3.1.3. PWM Pulse-width modulation (PWM) is a technique used to encode a message into a pulsing signal. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial loads such as motors. Pulse Width Modulation transmits the data by encoding the data into the duration of the pulses. More than one bit of data can be conveyed within each pulse. 3.1.4. PPM Pulse-position modulation (PPM) is a form of signal modulation in which M message bits are encoded by transmitting a single pulse in one of possible required time-shifts. This is repeated every T seconds, such that the transmitted bit rate is bits per second. It is primarily useful for optical communications systems, where there tends to be little or no multipath interference. 3.1.5. SIM-OFDM Sub-carrier Index Modulation OFDM is a technique which adds an additional dimension to the two dimensional amplitude/phase modulation technique i.e., Amplitude Shift Keying (ASK) and Quadrature Amplitude Modulation (QAM). SIM uses the subcarrier index to convey information to the receiver. Unlike the traditional OFDM technique, the SIM-OFDM technique splits the serial bit stream into two bit sub-streams of the same length.
  • 17.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 9 4. WHYVISIBLE LIGHT COMMUNICATION? The frequency spectrum that is available to us in the atmosphere consists of many wave regions like X-rays, gamma rays, ultraviolet region, infrared region, visible light rays, radio waves, etc. Anyone of the above waves can be used in the upcoming communication technologies but why the Visible Light part is chosen? The reason behind this is the easy availability and lesser harmful effects that occur due to these rays of light. VLC uses the visible light between 400 THz (780 nm) and 800 THz (375 nm) as medium which are less dangerous for high-power applications and also humans can easily perceive it and protect themselves from the harmful effects whereas the other wave regions have following disadvantages:  Radio waves are expensive (due to spectrum charges) and less secure (due to interference and possible interception etc.)  Gamma rays are harmful because it could be dangerous dealing with it, by the human beings due to their proven adverse effects on human health.  X-rays have health issues, similar to the Gamma Rays.  Ultraviolet light can be considered for communication technology purposes at place without people, otherwise they can also be dangerous for the human body when exposed continuously.  Infrared, due to high safety regulation, can only be used with low power. Hence the Visible light portion (from red to blue) of the electromagnetic spectrum does not cause any harm to the people as visible rays are safe to use, provide larger bandwidth and also have a promising future in the communication field.
  • 18.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 10 5. FEATURESAND BENEFITS Li-Fi features include benefits to the capacity, energy efficiency, safety and security of a wireless system with a number of key benefits over Wi-Fi but is inherently a complementary technology. 5.1. Bandwidth As we know, Li-Fi uses the visible light spectrum (400 THz to 800 THz), and this spectrum is plentiful (10,000 times more than RF spectrum), unlicensed and free to use, providing us a much greater bandwidth than Wi-Fi or any other wireless communication technology. Fig 5.1 Comparision in bandwidth of Radio frequencies and Light spectrum 5.2 Data density Li-Fi has a considerably high data density. The traditional radio frequencies, used in the wireless communication tend to spread out and cause interference. But this is not the case with visible light. Visible light is having the capability to be contained in a tight illumination area, which ultimately increases data density. A higher data density means more number of data packets transmitted per unit time.
  • 19.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 11 5.3. HighSpeed As discussed earlier, the Li-Fi is having a considerably high bandwidth, and a high data density. Moreover, the intensity of LED is also much higher. All these factors lead to the transmission of considerably higher amount of data per unit time, which ultimately increases the data transmission speed to a great extent. 5.4. Planning As the Li-Fi technology is based on the illumination infrastructure, a good signal strength can literally be seen. Also the intensity variation and switching of LED is fast enough that it can’t be seen by human eyes. This makes the capacity planning much easier. 5.5. Low Cost Li-Fi mainly uses LEDs and Photo Detectors for the transmission and reception of data, which makes it much cheaper than the current RF based wireless technologies, which are composed with numerous components. Also, the data transmission speed is 10-100 times higher in Li-Fi, which makes it much more cost efficient. 5.6. Efficiency LED is itself power efficient. And all the other components used in Li-Fi are minor power consumers. This makes Li-Fi a greatly power efficient technology. Moreover, we don’t need additional power for the Li-Fi, as it will be using the same power used for the illumination of a room. 5.7. Environment Transmission and propagation of RF in water is extremely difficult, which makes underwater communication impossible. But that’s not the case with Li- Fi, as it uses the visible spectrum of light; and the transmission and propagation of visible light in water is very easy.
  • 20.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 12 5.8. Safety Untilnow, there’s no known safety issues with Li-Fi, as it uses visible light. And visible light can never be harmful for anyone, considering the fact that the current RF technologies emit harmful radiation. The transmission of light avoids the use of radio frequencies which can dangerously interfere with electronic circuitry in certain environments. 5.9. Security For getting access to the Li-Fi signal, it is the prime need to keep the signal receiver directly in the illuminated area. In other words, no signal without direct light. This property prevents the Li-Fi network from the outside intruders, hackers and unwanted users. 5.10. Control Data may be directed from one device to another and the user can see where the data is going; there is no need for additional security such as pairing for RF interconnections such as Bluetooth. This gives the user a great control over what to send and where to send, and also prevents data leakage.
  • 21.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 13 6. COMPARISIONWITH Wi-Fi There are several advantages of Li-Fi over Wi-Fi:  Li-Fi uses light rather than radio frequency signals so are intolerant to disturbances.  VLC could be used safely in aircraft without affecting airlines signals.  Integrated into medical devices and in hospitals as this technology doesn’t deal with radio waves, so it can easily be used in all such places where Bluetooth, infrared, Wi-Fi and internet are broadly in use.  Under water in sea Wi-Fi does not work at all but light can be used and hence undersea explorations are good to go now with much ease.  There are billions of bulbs worldwide which just need to be replaced with LED’s to transmit data.  Security is a side benefit of using light for data transfer as it does not penetrate through walls.  On highways for traffic control applications like where Cars can have LED based headlights, LED based backlights, and they can communicate with each other and prevent accidents.  Using this Technology worldwide every street lamp would be a free data access point.  The issues of the shortage of radio frequency bandwidth may be sorted out by Li-Fi. The table on the next page shows the comparison of Li-Fi with Wi-Fi on various parameters.
  • 22.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 14 Table 6.1Comparison between Li-Fi and Wi-Fi on various parameters Parameter Li-Fi Wi-Fi Speed *** ** Data Density *** * Security *** ** Reliability *** ** Ecological Impact * ** Device-to-device Connectivity *** *** Obstacle Interference *** *
  • 23.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 15 7. DISADVANTAGES Everygood thing comes with a bad side. For example, in case of LiFi, internet cannot be used without a light source. This could limit the locations and situations in which Li-Fi could be used. Similarly, there are few more disadvantages, which should be taken care of.  Because it uses visible light, and light cannot penetrate walls, the signal's range is limited by physical barriers.  Other sources of light may interfere with the signal. One of the biggest potential drawbacks is the interception of signals outdoors. Sunlight will interfere the signals, resulting in interrupted Internet.  A whole new infrastructure for Li-Fi would need to be constructed.  Cost is also another factor. As each LED bulb requires a module attached to it to convert incoming data into flickers, it could be expensive to retrofit whole buildings with such equipment.  Computers or mobile devices will also need to be fitted with sensors that can read the light signals and convert them into data. The sensors are currently about the size of a smartphone and thus not very convenient for mobile users.  A device has to be within the line of sight of the light source, unlike Wi- Fi which can penetrate most walls.  The problem of how the receiver will transmit back to the transmitter still persists.  We become dependent on the light source for internet access. If the light source malfunctions, we lose access to the internet. But considering the fact that research works are still going on, there are bright chances that most of these problems will soon be eradicated in the near future.
  • 24.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 16 8. APPLICATIONS Thedramatic growth in the use of LEDs (Light Emitting Diodes) for lighting provides the opportunity to incorporate Li-Fi technology into a plethora of LED environments. Li-Fi is particularly suitable for many popular internet “content consumption” applications such as video and audio downloads, live streaming, etc. These applications place heavy demands on the downlink bandwidth, but require minimal uplink capacity. In this way, the majority of the internet traffic is off- loaded from existing RF channels, thus also extending cellular and Wi-Fi capacities. There are many applications for Li-Fi. These include: 8.1. RF Spectrum Relief Excess capacity demands of cellular networks can be off-loaded to Li-Fi networks where available. This is especially effective on the downlink where bottlenecks tend to occur. 8.2. Smart Lighting Any private or public lighting including street lamps can be used to provide Li- Fi hotspots and the same communications and sensor infrastructure can be used to monitor and control lighting and data. Fig 8.1 Smart Urban Lighting
  • 25.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 17 8.3. MobileConnectivity Laptops, smart phones, tablets and other mobile devices can interconnect directly using Li-Fi. Short range links give very high data rates and also provides security. Fig 8.2 Mobile Connectivity using Cellular, Wi-Fi and Li-Fi Networks 8.4. Hazardous Environments Li-Fi provides a safe alternative to electromagnetic interference from radio frequency communications in environments such as mines and petrochemical plants. 8.5. Hospital & Healthcare Li-Fi emits no electromagnetic interference and so does not interfere with medical instruments, nor is it interfered with by MRI scanners. Fig 8.3 Use of Li-Fi in Hospitals
  • 26.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 18 8.6. Aviation Li-Fican be used to reduce weight and cabling and add flexibility to seating layouts in aircraft passenger cabins where LED lights are already deployed. In- flight entertainment (IFE) systems can also be supported and integrated with passengers’ own mobile devices. 8.7. Underwater Communications Due to strong signal absorption in water, RF use is impractical. Acoustic waves have extremely low bandwidth and disturb marine life. Li-Fi provides a solution for short-range communications. Fig 8.4 Use of Li-Fi in Undewater communications 8.8. Vehicles & Transportation LED headlights and tail-lights are being introduced. Street lamps, signage and traffic signals are also moving to LED. This can be used for vehicle-to-vehicle and vehicle-to-roadside communications. This can be applied for road safety and traffic management.
  • 27.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 19 Fig 8.5Use of Li-Fi in Vehicles 8.9. RF Avoidance Some people claim they are hypersensitive to radio frequencies and are looking for an alternative. Li-Fi is a good solution to this problem. 8.10. Location Based Services (LBS) Highly accurate location-specific information services such as advertising and navigation that enables the recipient to receive appropriate, pertinent information in a timely manner and location. 8.11. Toys Many toys incorporate LED lights and these can be used to enable extremely low-cost communication between interactive toys. Fig 8.6 Use of Li-Fi in Toys
  • 28.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 20 9. FUTUREPOSSIBILITIES Li-Fi is purely a technology of future. It is having a potential to take over all the internet market on its own. The main points to be noted here are as follows:  With the advancement of Li-Fi technology, it will become more portable, taking its rightful places in our phones and laptops.  It will give the field of IoT a considerable boost as more and more number of devices will be able to connect and interact with each other through Li-Fi.  We will also be able to access the internet in places like Hospitals and Airplanes where traditional network systems can never be used.  Underwater communication will become much easier with the use of Li- Fi.  In future, it may be possible that we will be having an internet with a speed of multi gigabits per second.  With Li-Fi, we will also be moving towards a much more secured network, which will be safeguarding us from unwanted hackers.  Depletion of Environment due to increased use of radio frequencies will also decrease, as the Li-Fi technology uses the visible spectrum of light to transmit data.  Installation will also not be an issue with Li-Fi.  Multiuser support of Li-Fi will ensure that every individual is getting a high speed of internet. And these points will probably keep increasing as we will be moving forward towards the future.
  • 29.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 21 10.CONCLUSION Although there’sstill a long way to go to make this technology a commercial success, it promises a great potential in the field of wireless internet. A significant number of researchers and companies are currently working on this concept, which promises to solve the problem of lack of radio spectrum, space and low internet connection speed. By deployment of this technology, we can migrate to greener, cleaner, safer communication networks. The very concept of Li-Fi promises to solve issues such as, shortage of radio-frequency bandwidth and eliminates the disadvantages of Radio communication technologies. Li-Fi is the upcoming and growing technology acting as catalyst for various other developing and new inventions/technologies. Therefore, there is certainty of development of future applications of the Li-Fi which can be extended to different platforms and various walks of human life.
  • 30.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 APPENDIX ASK Amplitude-ShiftKeying FDM Frequency Division Multiplexing Gbps Gigabits per second IFE In-flight entertainment IoT Internet of Things LAN Local Area Network LBS Location Based Services LED Light-emitting Diode Li-Fi Light Fidelity Mbps Megabits per second MBps Megabytes per second QAM Quadrature Amplitude Modulation OFDM Orthogonal Frequency Division Multiplexing OOK On-off Keying PA Power Amplifier PCB Printed Circuit Board PPM Pulse-position Modulation PWM Pulse-width modulation RF Radio Frequency SIM-OFDM Sub-carrier Index Modulation OFDM THz TeraHertz UK United Kingdom VLC Visible Light Communication Wi-Fi Wireless Fidelity
  • 31.
    CSE-1(Y), 2nd Yr,4th Sem/Li-Fi/06.04.2018 REFERENCES https://en.wikipedia.org/wiki/Li-Fi Date andTime of visit: 08/03/2018 19:00 https://purelifi.com/technology/#what-is-lifi Date and Time of visit: 09/03/2018 22:20 http://tec.gov.in/pdf/Studypaper/lifi%20study%20paper%20-%20approved.pdf Date and Time of visit: 10/03/2018 20:32