The document is a seminar report on Li-Fi technology submitted for a bachelor's degree. It discusses the history and development of Li-Fi, which was coined by Professor Harald Haas. Li-Fi uses light from LED bulbs to transmit data wirelessly through variations in light intensity too fast for the human eye to detect. It provides several advantages over Wi-Fi such as higher speeds, more available bandwidth, and more secure transmission since light cannot pass through walls. The report explores applications of Li-Fi and how it works using visible light communication technology.

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LI-FI TECHNOLOGY
A Seminar report Submitted
in Partial Fulfillment of the Requirements
for the Degree of
BACHELOR OF TECHNOLOGY
in
Electronics & Communication Engineering
by
Ashish Agarwal
(1303231039)
Under the Supervision of
(Guide-Mr. Shailendra Bishariya)
to the
Faculty of Electronics & Communication Engineering
Dr. A.P.J. Abdul Kalam Technical University
Uttar Pradesh, Lucknow
March, 2016

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CERTIFICATE
Certified that Ashish Agarwal ( Roll no. 1303231039 ) has carried out the work presented
in this seminar entitled “ LI-FI Technology ” under my supervision.
Signature
Guide-Mr. Shailendra Bishariya
Electronics and Comm. Deptt.
Date: 9 March, 2016

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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 at 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, Prof. 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.
Haas says his invention, which he calls D-Light, can produce data rates faster than 10
megabits per second, which is speedier than your average broadband connection. He
envisions a future where data for laptops, smart phones, and tablets is transmitted through
the light in a room. And security would be a snap if you can’t see the light, you can’t access
the data.
Li-Fi is a VLC, visible light communication, technology developed by a team of
scientists including Dr. Gordon Povey, Prof. Harald Haas and Dr. Mostafa Afgani at the
University of Edinburgh. The term Li-Fi was coined by Prof. Haas when he amazed people
by streaming high-definition video from a standard LED lamp, at TED Global in July 2011.
Li-Fi is now part of the Visible Light Communications (VLC) PAN IEEE 802.15.7
standard.
“Li-Fi is typically implemented using white LED light bulbs. These devices are
normally used for illumination by applying a constant current through the LED. However,
by fast and subtle variations of the current, the optical output can be made to vary at
extremely high speeds. Unseen by the human eye, this variation is used to carry high-speed
data,” says Dr Povey, Product Manager of the University of Edinburgh's Li-Fi Program ‘D-
Light Project’.

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TABLE OF CONTENTS
Page No.
Certificate ii
Abstract iii
CHAPTER 1: INTRODUCTION TO LI-FI TECHNOLOGY 1
CHAPTER 2: GENESIS OF LI-FI 2
CHAPTER 3: HISTORY 3
CHAPTER 4: COMPARISION BETWEEN LI-FI & WI-FI 5
4.1 How it is different? 6
CHAPTER 5: HOW LI-FI WORKS? 8
5.1 Visible light communication (VLC) 9
5.2 Technology Brief 10
CHAPTER 6: WHY LI-FI? 12
CHAPTER 7: APPLICATION AREAS OF LI-FI TECHNOLOGY 14
7.1 Airways 14
7.2 You Might Just Live Longer 15
7.3 Green information technology 15
7.4 Free From Frequency Bandwidth Problem 16
7.5 Increase Communication Safety 16
7.6 Multi User Communication 16
7.7 Lightings Points Used as Hotspot 17
7.8 Smarter Power Plants 17
7.9 Undersea Awesomeness 17
7.10 It Could Keep You Informed and Save Lives 18
CHAPTER 8: ADVANTAGES OF LI-FI TECHNOLOGY 19
CHAPTER 9:DISADVANTAGES OF LI-FI TECHNOLOGY 19
CONCLUSION 20
REFERENCES 21

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CHAPTER 1: INTRODUCTION TO LI-FI TECHNOLOGY
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 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. More sophisticated techniques could
dramatically increase VLC data rates. Teams at the University of Oxford and the University
of Edinburgh are focusing on parallel data transmission using arrays of LEDs, where each
LED transmits a different data stream. Other groups are using mixtures of red, green and
blue LEDs to alter the light's frequency, with each frequency encoding a different data
channel.
Fig.1 Li-Fi environment

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Li-Fi, as it has been dubbed, has already achieved blisteringly high speeds in the lab.
Researchers at the Heinrich Hertz Institute in Berlin, Germany, have reached data rates of
over 500 megabytes per second using a standard white-light LED. Haas has set up a spin-off
firm to sell a consumer VLC transmitter that is due for launch next year. It is capable of
transmitting data at 100 MB/s - faster than most UK broadband connections.
CHAPTER 2: GENESIS OF LI-FI
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 blooming flowers that was then projected onto a screen behind him.
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.
Prof. Harald Haas

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CHAPTER 3: HISTORY
Professor Harald Haas, from the University of Edinburgh in the UK, is widely recognised as
the original founder of Li-Fi. He coined the term Li-Fi and is Chair of Mobile
Communications at the University of Edinburgh and co-founder of pureLiFi.
The general term visible light communication (VLC), includes any use of the visible light
portion of the electromagnetic spectrum to transmit information. The D-Light project at
Edinburgh's Institute for Digital Communications was funded from January 2010 to January
2012. Haas promoted this technology in his 2011TED Global talk and helped start a
company to market it. PureLiFi, formerly pureVLC, is an original equipment
manufacturer (OEM) firm set up to commercialize Li-Fi products for integration with
existing LED-lighting systems.
In October 2011, companies and industry groups formed
the Li-Fi Consortium, to promote high-speed optical wireless systems and to overcome the
limited amount of radio-based wireless spectrum available by exploiting a completely
different part of the electromagnetic spectrum. A number of companies offer uni-directional
VLC products which is not the same as Li-Fi.
VLC technology was exhibited in 2012 using Li-Fi. By August 2013, data rates of over
1.6 Gbps were demonstrated over a single color LED. In September 2013, a press release
said that Li-Fi, or VLC systems in general, do not require line-of-sight conditions. In
October 2013, it was reported Chinese manufacturers were working on Li-Fi development
kits.
One part of VLC is modeled after communication protocols established by
the IEEE workgroup. However, the IEEE 802.15.7 standard is out-of-date. Specifically, the
standard fails to consider the latest technological developments in the field of optical
wireless communications, specifically with the introduction of optical orthogonal
frequency-division multiplexing (O-OFDM) modulation methods which have been
optimized for data rates, multiple-access and energy efficiency have. The introduction of O-
OFDM means that a new drive for standardization of optical wireless communications is
required.
Nonetheless, the IEEE 802.15.7 standard defines the physical layer (PHY)
and media access control (MAC) layer. The standard is able to deliver enough data rates to

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transmit audio, video and multimedia services. It takes into account the optical transmission
mobility, its compatibility with artificial lighting present in infrastructures, the devience
which may be caused by interference generated by the ambient lighting. The MAC layer
allows to use the link with the other layers like the TCP/IP protocol.
Li-Fi, or light fidelity, refers to 5G visible light communication systems using light
from light-emitting diodes (LEDs) as a medium to deliver networked, mobile, high-speed
communication in a similar manner as Wi-Fi. Li-Fi could lead to the Internet of Things,
which is everything electronic being connected to the internet, with the LED lights on the
electronics being used as internet access points. The Li-Fi market is projected to have a
compound of 82% from 2013 to 2018 and to be worth over $6 billion per year by 2018.
Visible light communications (VLC) signals work by switching bulbs on and off
within nanoseconds, which is too quickly to be noticed by the human eye. Although Li-Fi
bulbs would have to be kept on to transmit data, the bulbs could be dimmed to the point that
they were not visible to humans and yet still functional. The light waves cannot penetrate
walls which makes a much shorter range, though more secure from hacking, relative to Wi-
Fi. Direct line of sight isn't necessary for Li-Fi to transmit signal and light reflected off of
the walls can achieve 70 Mbps.

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CHAPTER 4: .COMPARISION BETWEEN LI-FI & WI-FI
LI-FI is a term of one used to describe visible light communication technology applied to
high speed wireless communication. It acquired this name due to the similarity to WI-FI,
only using light instead of radio. WI-FI is great for general wireless coverage within
buildings, and Li-Fi is ideal for high density wireless data coverage in confined area and for
relieving radio interference issues, so the two technologies can be considered
complimentary
Table 1.Comparison between Li-Fi and Wi-Fi Technology.

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Table 2.Comparison between current and future wireless technology
*The below table also contains the current wireless technologies that can be used for
transferring data between devices today, i.e. Wi-Fi, Bluetooth and IrDA. Only Wi-Fi
currently offers very high data rates. The IEEE 802.11.n in most implementations provides
up to 150Mbit/s (in theory the standard can go to 600Mbit/s) although in practice you
receive considerably less than this. Note that one out of three of these is an optical
technology.
4.1 How it is different?
Li-Fi technology is based on LEDs for the transfer of data.
The transfer of the data can be with the help of all kinds of light, no matter the part of the
spectrum that they belong. That is, the light can belong to the invisible, ultraviolet or the
visible part of the spectrum. Also, the speed of the internet is incredibly high and you can
download movies, games, music etc in just a few minutes with the help of this technology.

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Also, the technology removes limitations that have been put on the user by the
Wi-Fi. You no more need to be in a region that is Wi-Fi enabled to have access to the
internet. You can simply stand under any form of light and surf the internet as the
connection is made in case of any light presence. There cannot be anything better than this
technology.
Fig 2.Working and advantages

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CHAPTER 5: HOW LI-FI WORKS?
Li-Fi is typically implemented using white LED light bulbs at the downlink transmitter.
These devices are normally used for illumination only by applying a constant current.
However, by fast and subtle variations of the current, the optical output can be made to vary
at extremely high speeds.
This very property of optical current is used in Li-Fi setup. The
operational procedure is very simple-, if the LED is on, you transmit a digital 1, if it’s off
you transmit a 0. The LEDs can be switched on and off very quickly, which gives nice
opportunities for transmitting data. Hence all that is required is some LEDs and a controller
that code data into those LEDs. All one has to do is to vary the rate at which the LED’s
flicker depending upon the data we want to encode.
Further enhancements can be made in this method, like using an array of LEDs for parallel
data transmission, or using mixtures of red, green and blue LEDs to alter the light’s
frequency with each frequency encoding a different data channel. Such advancements
promise a theoretical speed of 10 Gbps – meaning one can download a full high-definition
film in just 30 seconds. Simply awesome! But blazingly fast data rates and depleting
bandwidths worldwide are not the only reasons that give this technology an upper hand.
Since Li-Fi uses just the light, it can be used safely in aircrafts and hospitals that are prone
to interference from radio waves. This can even work underwater where Wi-Fi fails
completely, thereby throwing open endless opportunities for military operations.
Imagine only needing to hover under a street lamp to get public internet access, or
downloading a movie from the lamp on your desk. There's a new technology on the block
which could, quite literally as well as metaphorically, 'throw light on' how to meet the ever-
increasing demand for high-speed wireless connectivity. Radio waves are replaced by light
waves in a new method of data transmission which is being called Li-Fi.Light-emitting
diodes can be switched on and off faster than the human eye can detect, causing the light
source to appear to be on continuously. A flickering light can be incredibly annoying, but
has turned out to have its upside, being precisely what makes it possible to use light for
wireless data transmission. Light-emitting diodes (commonly referred to as LEDs and found
in traffic and street lights, car brake lights, remote control units and countless other
applications) can be switched on and off faster than the human eye can detect, causing the

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light source to appear to be on continuously, even though it is in fact 'flickering'. This
invisible on-off activity enables a kind of data transmission using binary codes: switching
on an LED is a logical '1', switching it off is a logical '0'. Information can therefore be
encoded in the light by varying the rate at which the LEDs flicker on and off to give
different strings of 1s and 0s. This method of using rapid pulses of light to transmit
information wirelessly is technically referred to as Visible Light Communication (VLC),
though it’s potential to compete with conventional Wi-Fi has inspired the popular
characterization Li-Fi.
5.1 Visible light communication (VLC)-“A potential solution to the global
wireless spectrum shortage”
LiFi (Light Fidelity) 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 1) a high
brightness white LED, Which acts as a communication source and 2) 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.

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Fig 3.Data transmission using LED
5.2Technology Brief ( How LI-FI Light Sources Work ) :
Introduction:
LI-FI is a new class of high intensity light source of solid state design bringing clean
lighting solutions to general and specialty lighting. With energy efficiency, long useful
lifetime, full spectrum and dimming, LI-FI lighting applications work better compared to
conventional approaches. This technology brief describes the general construction of LI-FI
lighting systems and the basic technology building blocks behind their function.

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Li-Fi Construction:
The LIFI™ product consists of 4 primary sub-assemblies:
• Bulb
• RF power amplifier circuit (PA)
• Printed circuit board (PCB)
• Enclosure
 The PCB controls the electrical inputs and outputs of the lamp and houses the
microcontroller used to manage different lamp functions.
 An RF (radio-frequency) signal is generated by the solid-state PA and is guided
into an electric field about the bulb.
 The high concentration of energy in the electric field vaporizes the contents of
the bulb to a plasma state at the bulb’s center; this controlled plasma generates an
intense source of light.
All of these subassemblies are contained in an aluminum enclosure.
Function Of The Bulb:
:At the heart of LIFI™ is the bulb sub-assembly where a sealed bulb is embedded in a
dielectric material. This design is more reliable than conventional light sources that insert
degradable electrodes into the bulb. The dielectric material serves two purposes; first as a
waveguide for the RF energy transmitted by the PA and second as an electric field
concentrator that focuses energy in the bulb. The energy from the electric field rapidly
heats the material in the bulb to a plasma state that emits light of high intensity and full
spectrum.
Summary:
The design and construction of the LIFI™ light source enable efficiency, long stable life,
full spectrum intensity that is digitally controlled and easy to use

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CHAPTER 6: WHY LI-FI ?
 We have 1.4 million cellular radio waves base stations deployed.
 We also have over 5 billions of mobile phones.
 Mobile phone transmits more than 600TBb of data.
 Wireless communication has become a utility like electricity & water.
 We use it in everyday life, in our private life, business life.
 Currently wifi uses Radio waves for communication.
 It is important to look into this technology which has become fundamental to our life.
Four Issues with Radio Waves:
1. Capacity:
 We transmit wireless data through radio waves.
 Radio waves are limited, scar and expensive.
 We only have a certain range of it.
 With the advent of the new generation technologies as of likes of 2.5G, 3G,
4G and so on we are running out of spectrum.
2. Efficiency:
 There are 1.4 million cellular radio base stations.
 They consume massive amount of energy.
 Most of this energy is not used for transmission but for cooling down the
base stations.
 Efficiency of such a base station is only 5% and that raise a very big
problem.

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3. Availability:
 We have to switch off our mobiles in aeroplanes.
 It is not advisable to use mobiles at places like petrochemical plants and
petrol pumps.
 Availability of radio waves causes another concern.
4. Security:
 Radio waves penetrate through walls.
 They can be intercepted.
 If someone has knowledge and bad intentions then he may misuse it.
 Alternative to Radio waves in Electromagnetic Spectrum:
 So there are four major concerns i.e., capacity, efficiency, availability,
security related with Radio waves.
 But on the other hand we have 40 billions of light box already installed and
light is part of electromagnetic spectrum.
 So let’s look up at this in context of EM spectrum.
Fig 4.Electromagnetic spectrum showing radio wave and visible spectrum bandwidth.

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 Gamma rays are simply very dangerous and thus can’t be used for our purpose of
communication.
 X-rays are good in hospital and can’t be used either.
 Ultra-violet rays are sometimes good for our skin but for long duration it is
dangerous.
 Infra-red rays are bad for our eyes and are therefore used at low power levels.
 We have already seen shortcomings of radio waves.
 So we are left with only Visible light spectrum.
CHAPTER 7: APPLICATION AREAS OF LI-FI TECHNOLOGY
7.1 Airways:
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
overcomes this drawback on radio waves , li-fi is introduce.
Fig 5. Shows In-Flight Entertainment using Li-Fi.

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7.2 You Might Just Live Longer :
For a long time, medical technology has lagged behind the rest of the wireless world.
Operating rooms do not allow Wi-Fi over radiation concerns, and there is also that whole
lack of dedicated spectrum. While Wi-Fi is in place in many hospitals, interference from
cell phones and computers can block signals from monitoring equipment. Li-Fi solves both
problems: lights are not only allowed in operating rooms, but tend to be the most glaring
(pun intended) fixtures in the room. And, as Haas mentions in his TED Talk, Li-Fi has
10,000 times the spectrum of Wi-Fi, so maybe we can, I dunno, delegate red light to priority
medical data. Code Red!
Fig 6. Shows implementation of Li-Fi in Operation Theater.
7.3 Green information technology:
Green information technology means that unlike radiowaves and other communication
waves affects on the birds , human bodys etc. Li-Fi never gives such side effects on any
living thing.

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7.4 Free From Frequency Bandwidth Problem:
Li-fi is an communication media in the form of light ,so no matter about the frequency
bandwidth problem . It does not require the any bandwidth spectrum i.e. we don’t need to pay
any amount for communication and licence.
7.5 Increase Communication Safety:
Due to visual light communication , the node or any terminal attach to our network is visible to
the host of network .
7.6 Multi User Communication:
Li-Fi supports the broadcasting of network , it helps to share multiple thing at a single instance
called broadcasting.
Fig7. Shows every street lamps acting as a Li-Fi Hotspot.

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7.7 Lightings Points Used as Hotspot:
Any lightings device is performed as a hotspot it means that the light device like car lights,
ceiling lights , street lamps etc area able to spread internet connectivity using visual light
communication. Which helps us to low cost architecture for hotspot. Hotspot is an limited
region in which some amount of device can access the internet connectivity .
Fig 8 .Shows every light emmiting device acting as a Li-Fi Hotspot
7.8 Smarter Power Plants:
Wi-Fi and many other radiation types are bad for sensitive areas. Like those surrounding power
plants. But power plants need fast, inter-connected data systems to monitor things like demand,
grid integrity and (in nuclear plants) core temperature. The savings from proper monitoring at a
single power plant can add up to hundreds of thousands of dollars. Li-Fi could offer safe,
abundant connectivity for all areas of these sensitive locations. Not only would this save money
related to currently implemented solutions, but the draw on a power plant’s own reserves could
be lessened if they haven’t yet converted to LED lighting.
7.9 Undersea Awesomeness:
Underwater ROVs, those favourite toys of treasure seekersand James Cameron, operate from
large cables that supplytheir power and allow them to receive signals from their pilotsabove.
ROVs work great, except when the tether isn’t longenough to explore an area, or when it gets
stuck on something.If their wires were cut and replaced with light — say from asubmerged,

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high-powered lamp — then they would be muchfreer to explore. They could also use their
headlamps tocommunicate with each other, processing data autonomouslyand referring
findings periodically back to the surface, all the while obtaining their next batch of orders.
Fig 9. Shows under water implementation of Li-Fi.
7.10. It Could Keep You Informed and Save Lives :
Say there’s an earthquake in New York. Or a hurricane. Take your pick — it’s a wacky city.
The average New Yorker may not know what the protocols are for those kinds of disasters.
Until they pass under a street light, that is. Remember, with Li-Fi, if there’s light, you’re online.
Subway stations and tunnels, common dead zones for most emergency communications, pose
no obstruction. Plus, in times less stressing cities could opt to provide cheap high-speed Web
access to every street corner.

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CHAPTER 8: ADVANTAGES OF LI-FI TECHNOLOGY
Li-Fi can solve problems related to the insufficiency of radio frequency bandwidth because
this technology uses Visible light spectrum that has still not been greatly utilized.
 High data transmission rates of up to 10Gbps can be achieved.
 Since light cannot penetrate walls, it provides privacy and security that Wi-Fi
cannot.
 Li-Fi has low implementation and maintenance costs.
 It is safe for humans since light, unlike radio frequencies, cannot penetrate human
body. Hence, concerns of cell mutation are mitigated.
CHAPTER 9: DISADVANTAGES OF LI-FI TECHNOLOGY
Light can't pass through objects.
 A major challenge facing Li-Fi is how the receiving device will transmit back to
transmitter.
 High installation cost of the VLC systems.
 Interferences from external light sources like sun, light, normal bulbs, opaque
materials.

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CONCLUSION
The possibilities are numerous and can be explored further. If his technology can be put into
practical use, every bulb can be used something like a Wi-Fi hotspot to transmit wireless
data and we will proceed toward the cleaner, greener, safer and brighter future.
The concept of Li-Fi is currently attracting a great deal of interest, not least because it may
offer a genuine and very efficient alternative to radio-based wireless. As a growing number
of people and their many devices access wireless internet, the airwaves are becoming
increasingly clogged, making it more and more difficult to get a reliable, high-speed signal.
This may solve issues such as the shortage of radio-frequency bandwidth and also allow
internet where traditional radio based wireless isn’t allowed such as aircraft or hospitals.
One of the shortcomings however is that it only work in direct line of sight.

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REFERENCES
1. www.seminarsonly.com
2. www.slideshare.in
3. www.wikipidea.com
4. www.purelifi.com
5. www.lifi-centre.com
6. www.youtube.com
7. Link: http://timesofindia.indiatimes.com/home/science/Now-just-light-a-bulb-to-
switch-on-your-broadband/articleshow/9713554.cms