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IJSART - Volume 1
Issue 5 –MAY 2015
ISSN [ONLINE]: 2395-1052
Li-Fi –Future of Wireless
Ashvanth Ramesh Kumar1, Aarthi R2
Department of Computer Science
1
Illinois Institute of Technology,Chicago,USA
2
RMD Engineering College, Tamil Nadu, India
Abstract- Light-Fidelity in short called as Li-Fi was proposed
by a Germanphysicist Harald Hass.Li-Fi is considered as the
future of wireless technology. It uses light as a transmission
medium which in turn results in the data transmission through
illumination. The intensity of an LED light bulb varies much
faster which cannot be captured by human eye.This paper
mainly focuses on developing a Li-Fibased system and
analyzes its performance with respect toexisting technology.
Wi-Fiis very much suitable to provide internet access within
the buildings and on the other hand Li-Fi is ideal for high
density wireless data coverage in confined area. Li-Fi can be
considered as a Light based Wi-Fi and has a better data rates,
security and efficiency when compared to Wi-Fi.Li-Fi uses
only LED lamps whichare easily available at low cost and this
in turn helps us to have internet access through street lights to
high speed cars which can communicate through their
headlights. This technology is mainly focused for laptops,PDA
gadgets and smart phones which will access to the internet
with the help of LED lamps fitted in the room.
Keywords- Light-Fidelity (Li-Fi), Light Emitting Diode (LED),
Wireless-Fidelity (Wi-Fi).
I. INTRODUCTION
Internet is playing a vital role in our day today
activities. People are connecting to network either through
wired medium or through wireless medium. We need to
transfer data from one system to another to complete our
activity. When multiple system access the same access point
the data transfer rate will be reduced because only a fixed
bandwidth is available to access the internet. For example, In a
Mall there will be a free Wi Fi zone but the network quality
will be very minimal because many people access the internet
which in turn results in poor internet access.
transmission medium which in turn results in the data
transmission throughillumination. The intensity of an LED
light bulb (shown in Fig. 1)varies much faster which cannot be
captured by human eye.
A German physicist, Harald Hass introduced the
concept called D light which is referred to as data through
Illumination. He called it as D light, which can produce a data
rate of higher than 10 megabits per second. It is then later
called as Li Fi.
Li-Fi is a part ofvisible light communication (VLC)
PAN IEEE 802.15.7 standard. Li Fi offers a larger frequency
band of around 300 THz but on the other hand RF
communications can give a frequency band of 300GHz.
Li-Fi uses only LED lamps which are easily available
at low cost and this in turn helps us to have internet access
through street lights to high speed cars which can
communicate through their headlights.[2] This technology is
mainly focused for laptops, PDA gadgets and smart phones
which will access to the internet with the help of LED lamps
fitted in the room.Li Fi can also be used in Military areas
where security is a primary concern.[3]
Fig 2 Overview of Li-Fi
II. DESIGN OF LI-FI
Li-Fi architecture is designed to have more numbers
of Light emitting diodes or lamps, and numerous wireless
devices such as Smart Phones, Laptops, and PDA
gadgets.Primary factors which should be taken care while
designing Li-Fi are
Fig. 1. Li-Fi bulb
The problem can be solved by using Li-Fi
technology. Li-Fi denotesLight-Fidelity.It uses light as a
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Presence of Light
Line of Sight (Los)
Fluorescent light &light emitting diodes should be
used to have better performance
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IJSART - Volume 1
Issue 5 –MAY 2015
ISSN [ONLINE]: 2395-1052
IV. FUNCTION OF BLUB SUB ASSEMBLY
Fig. 3 Architecture of Li-Fi
As shown in figure 3, the efficiency of the Li Fi lies
in the streaming content integration with server & internet
network.
As shown in the Block diagram of Li-Fi subassemblies, the sealed bulb is embedded in a dielectric
material. This Li Fi makes the design more reliable. The main
purposes of using the dielectric material are:
1. It acts as a waveguide for the RF energy transmitted
by the RF power amplifier circuit.
2. As a concentrator for electric field that mainly
focuses on energy in the bulb.
III. CONSTRUCTION OF LI-FI SYSTEM
Li-Fi is called as Light Bases Wi Fi and it is very fast
and economical optical version of Wi-Fi.[8] Li Fi uses Visible
Light Communication (VLC).VLCuses visible light between
400THz (780 nm) and 800 THz (375 nm) as optical carrier
fordata transmission and illumination.Li Fi mainly consists of:
a) Transmission source:A high brightness white Fluorescent
light or light emitting diodes.
Fig 5 Bulb sub-assembly
V. WORKING OF LI-FI
b) ReceivingElement: A silicon photodiode which has a good
response to visible light.
The sub-assemblies of Li Fi are as follows:
• Bulb
• PA (RF power amplifier circuit)
• PCB (Printed circuit board)
• Enclosure
Electrical inputs and outputs of the lamp are
controlled by PCB and the other lamp functions are controlled
by the micro controller. Solid-state PA generates the RF
(radio-frequency) signal and this in turn helps in driving
electric field about the blub.[11]The blub contents are vaporized
to a plasma state due to the concentration of energy in the
electric field and this controlled plasma produces an intense
source of light.
Fig.4 Block diagram of Li-Fi sub-assemblies
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Light-emitting diodes act as a transmission source for
the Li Fi technology. Digital 1 is transmitted if the LED is
switched ON and Digital 0 is transmitted if the LED is
switched OFF. The LED lamps can be turned ON and OFF
instantly which helps in efficient transmission of data through
light. [9]
Li Fi has a light emitter on one end, for example,
Light - emitting diodes, and a photo detector on the other end.
Binary one is registered when the LED is switched ON by the
photo detector and when the LED is switched OFF, Binary
zero is registered.[11] Different data rates can be obtained when
array of LED‟s with different colors is used.
Fig. 6 Block diagram of Li-Fi system
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IJSART - Volume 1
Issue 5 –MAY 2015
When Light-emitting diodes are switched ON and
OFF we will be able to generate different combinations of
Zeros and One. Human eye cannot detect the intensity of the
LED lamps which varies rapidly.[16]Light-emitting diodes
commonly referred to as LEDs are used in our day today
commodities like street lights, car head lights, remote control
units and other applications. The data rates can be varied by
switching ON and OFF the LED lamp which helps in the
transmission information and this is called as Visible Light
Communication (VLC).[12]Li-Fi is now part of visible light
communication (VLC) PAN IEEE 802.15.7 standard.
Fig.7 Li-Fi system connecting devices in a room.
The above figure shows how Li Fi i.e. Light can used
a transmission medium. All the gadgets like PDBA, Laptops
should be in the Line of sight to the electric blub to achieve
high data rate.
VI. COMPARISION WITH EXISITING WIRELESS
TECHNOLOGY
Li Fi is a part of visible light communication which
helps in high transfer rate.[15] Li Fi can be treated as a Light
Based Wi Fi. Li Fi uses light whereas Wi Fi uses the radio
spectrum. Li-Fi is ideal for high density wireless data
coverage in confined area and Wi Fi is used for wireless
coverage and the coverage areas are confined within the
buildings.
Table I shows a comparison of transfer speed of
various Wireless technologies. Table II shows a comparison of
various Technologies that are used for connecting to the end
user.
ISSN [ONLINE]: 2395-1052
WI Gig
Giga-IR
Li-Fi
Future Wireless System
2 Gbps
1 Gbps
>1Gbps
TABLE II.COMPARISON OF SPEED OF VARIOUS
WIRELESSES TECHNOLOGIES
Li Fi
Characteristics Blue tooth
WiFi
Frequency
2.4 Hz
2.4 Hz –
5GHz
No
frequency
for light
Range
10 meters
100 meters
Based on
LED light
falling
Data Transfer
rate
800 kbps
11Mbps
>1Gbps
Operating
Band
ISM Band
RF Band
Visible
Light Band
Working
Concept
MasterSlave
Various
Topologies
Direct
Binary Data
Serving
The above table gives us the compare the various
features present in the existing wireless technology and that in
turn compared with Li-Fi which is considered as the future of
wireless.
VII. MERITS OF LI-FI
Li Fi technology has the fastest data transfer rate and
we can download HD videos and large amounts of data‟s in
GB within fraction of seconds.[17] Li Fi technology mainly
depends on the LED lamps or other light sources for the
transfer of data. Wi Fi has more number of limitations and this
has been overcome by Li Fi. The advantages of Li Fi
technology are as follows:
TABLE I.COMPARISON OF SPEED OF VARIOUS
WIRELESS TECHNOLOGIES
Technology
Speed
Current Wireless System
a) Capacity: Wi Fi uses the radio spectrum and we are
running out of spectrum availability. On the other hand, Li Fi
which uses Light has wider bandwidth when compared to that
of radio waves. So, Li Fi has a wider bandwidth and better
capacity.
Wi-Fi – IEEE 802.11n
Bluetooth
IrDA
b) Efficiency:The efficiency of the radio wave base station is
only 5% because more amount of energy is spent on cooling
the base station than in the transmission. On the other hand, Li
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150 Mbps
3 Mbps
4 Mbps
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IJSART - Volume 1
Issue 5 –MAY 2015
ISSN [ONLINE]: 2395-1052
Fi uses LED lamps for data transmission which consumes less
energy and the overall efficiency is also high.
c) Availability: Radio spectrum cannot be used in all places
but Li Fi uses Light as a source for data transmission and light
bulbs are used universally.
d) Security: Light waves in LI Fi cannot not penetrate
through walls. So, they can„t be misused and can be used for
secure purposes.
VIII. SHORTCOMINGS OF LI-FI
Some of the short comings of using Li Fi technology are as
follows:
A.
External light cannot travel into walls and other
opaque materials.
B.
Li-Fi enabled end device (through its inbuilt photoreceiver) will never be as fast and handy as a Wi-Fi
enabled device in the open air.
C.
Always works in the Direct Line of Sight
.
Fig.8 Smarter Power Plants
d) Airlines: Internet access in the aircrafts is very minimal
and it is offered at high price. Wi Fi usage is limited in
aircrafts because it may get interfered with the navigational
systems of the pilots. So, this interference can be overcome by
using Li Fi which provides the high speed internet via the light
sources present inside the cabin with minimal cost. [21]
IX. APPLICATIONS OF LI-FI
Li Fi uses LED lamps for data transmission and has
numerous applications. The future applications of Li Fi are as
follows:
A) Educationsystems: Li-Fi provides us high speed internet
access. So, Wi Fi can be replaced by Li Fi in education
system. Using Li-Fi, we can listen to Online lectures easily
without any buffering time.[20]
b) Health technologies: Wi Fi should not be used in hospitals
because the radio spectrum blocks the signals of the
monitoring equipment. Due to radiation concerns, Wi FI is not
allowed in Operation theatres (OTs). [7] Li Fi can be used in
hospitals without affecting patient‟s health. This helps in
involving robots to perform surgeries and other automated
process.
c) Power Plants: Wi-Fi and many other radiation or radio
waves are harmful for sensitive areas like thoseof power plants
especially the atomic power plants. Nuclear power plants need
fast, some wireless technology to monitor things like demand,
grid integrity and core temperature and inter-connected data
systems. The efficiency of the plant can be improved if
monitoring is done well. [3]Li Fi can provide more accurate
data and helps in increasing the overall effectiveness of the
system.
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Fig.9Airlines
e) Under Sea Working: Li Fi has a major role in under sea
communications. Underwater Rovers, which is also called toys
of treasure seekers, operate from long cables.ROV receive
signals from their pilots above. The radio communication
work efficiently in a small area. [5]If Li Fi is used they can use
a high-powered lamp and can explore more. The explorers can
even interact with each other using their headlights and can
obtain their orders from the source.
f) Traffic management: LED lamps acts as a primary source
for Li Fi.LED lamps are present in the headlights of the car
and helps in managing the traffic and accidents numbers. LED
car lamps can also alert drivers about the car/vehicle which is
near to it.
X. CONCLUSION
Li-Fi is not limited to LED or laser technologies and
has wide range of operating frequencies and wavelength. Li Fi
supports both unidirectional and bidirectional data transfer
using line-of-sight. If Li Fi is put into practice, every LED
lamp will acts as a Wi Fi hotspot and helps in transmission of
wireless data. This will help in the safer, cleaner andecowww.ijsart.com
IJSART - Volume 1
Issue 5 –MAY 2015
friendlyfuture. The demand for wireless internet is keep on
increasing due to more number of smart phones into the
market and this clogs the available radio spectrum. Li Fi has a
broader application area where Wi Fi fails to support. But, one
of the major short comings is Li Fi works only on the Direct
Line of Sight.
ISSN [ONLINE]: 2395-1052
[7] http://articles.economictimes.indiatimes.com/2013-0114/news/36331_1_data-transmission-trafficvisiblespectrum
[8] http://www.extremetech.com/extreme/147339-micro-ledlifi-whereevery-light-source-in-the-world-is-also-tv-andprovides-gigabit-internetaccess
XI. FUTURE ENHANCEMENTS
Li Fi system can be further enhanced by using array
of LED‟s which helps in parallel data transmission and the
light frequency can be varied by using mixture of red, green
and blue LEDs. We can expect a speed of about 10 Gbps by
using Li Fi technology and this result in download of high
definition film with in fraction of seconds.
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IJSART - Volume 1
Issue 5 –MAY 2015
ISSN [ONLINE]: 2395-1052
coming”, Economist,dated 28Jan 2012
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ABOUT THE AUTHORS
Ashvanth did his Bachelor‟sDegree in
Electronics and Communication and has a
keen interest in the field of Electronics
and Computer Science. He has an
industrial experience of around 2.5 years
and Currently doing his Masters in
Computer Science at Illinois Institute of
Technology, Chicago, USA.
Aarthi did her Bachelor‟s Degree in the
field of Electronics and Communication
and has published many research papers.
She did her Masters in the field of
Applied Electronics and working as a
Assistant Professor in RMD Engineering
for past 4 years and handled many papers
on Digital Communication, Control
Systems. She is also acting as research
guide for her students in the field of VLSI
and Communication Systems.
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