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Li-Fi(Light Fidelity)
The future technology In Wirele
communication
-By
Sandeep Jangir
Sankalp Shrivastav
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Overview
History
Scope and Need of Li-Fi
Working with Li-Fi
Principle of Li-Fi
VLC (Visible light Communication)
Importance of using VLC
Devices used in VLC
Contraction of Li-Fi products
How Li-Fi works
Advantages & Application of Li-Fi
Challenges & Myths
Conclusion & References
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Overview
LI-FI describes transmission of data through illumination taking the fiber o
optic by sending data through an LED light bulb that varies in intensity fastehuman eye can follow .Radio waves are replaced by light waves in a new m
transmission which is being called Li-Fi. It produce data rates faster than 10
second, which is speedier than your average broadband connection and W
any kind of light source then you can access internet or data transmission a
time at high speed, If you cant see the light you cant access internet (Says
who invented this technology).
Keywords :
1. LI-FI(light fidelity)
2. LED(light emitting diode)
3. WI-FI(wireless fidelity)
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History:
The technology truly began during the 1990's in countries like Germany, Ko
Japan where they discovered LED's could be retrofitted to send information
of light would come in familiar forms such as infrared, ultraviolet, and visibl
type of light rays carries some energy. So the researchers think that why noenergy can be used for the data transmission. With this thought journey of
Several projects were carried out for this. But the project is facing early cha
such as finding ways to get devices to receive data from affixed
light sources.
German-born Haas sits in his office in Edinburgh University. Several of the u
faculties, led by the informatics department, are involved in his project, callLIGHT; the university, a sponsor, owns the intellectual property. Haas coined
Li-Fi in 2011 in the context of a talk presenting the new technology at the TE
(Technology Entertainment and Design) Global conference. There he give h
demonstration of how we might rely upon light bulbs for cell phone service
and wireless networks in the home. The word quickly entered common par
instantly recognizable alternative to Wi-Fi.
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Need of LI-FINow a day we are seeing that human need more fast data transmission to sav
increasing the speed if we go for the wire lines it will cost higher and we
systems. But today we need a wireless network so that we can use it freely
inside its range. So a possible solution is the using mobile networking. But it for the local networking. For local networking one option of wi-fi is also availa
the major problems that present it is the already limited spectrum
communications. The remaining free spectrum has to be used to its maxi
spread spectrum technology presenting itself as a suitable means
performance. Splitting up of the environment into a number of small cells als
overall accessible bandwidth of the communication system, but also increamore cell sites are required. So it becomes costly. Security is also one of th
There are many proxy server such as hotspot, tor are available which can
WIFI system and provide the unauthorized browsing to the user.
Some health issue are also related with WIFI. Researchers are going on to fin
wi fi to human health. So to prevent all of these problems we need Li
electromagnetic spectrum.
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Working of LI-FI
Heart of Li-Fi technology is high brightness LEDs. Light emitting diodes can b
and off faster since operating speed of LEDs is less than one s, than the hu
detect, causing the light source to be appear continuously. This invisible on-
enables a kind of data transmission using binary codes. Switching on and LED
switching it off is a logical 0.It is possible to encode data in the light by vary
which LEDs flicker on and off to give different strings of 1s and 0s. Modulati
that human eye doesnt notice . A light sensitive device (photo detector) recand converts it back into original data. This method of using rapid pulses of
information wirelessly is technically referred as Visible Light Communication
its potential to compete with conventional Wi-Fi has inspired the popular ch
Fi.
Principle of LI-FI :
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Working with LI-FI
Li-Fi is a fast and cheap version of Wi-Fi, which is based on visible light comm
(VLC). The Visible light communication is a data communications medium usbetween 400 THz (780 nm) and 800 THz (375nm) as optical carrier for data t
and illumination [12]. Visible light is not injurious to vision.
Typical example of visible light communication is given in fig. below.
VLC (visible light communication)
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Visible light LED can be used almost everywhere. Infrared light is already u
communication such as wireless remote control, Infrared wireless LAN and Ininter-building communication. Visible light LEDs are beginning to be used in
home and office, which makes visible light LEDs ideal for ubiquitous data tra
Growth rate of LED lighting is expected to triple from 2009 to 2012 & market
LED lighting will be more than 30 % of total lighting market in 2016.
Image sensors can be used as receivers. The use of image sensors as receiv
possible to detect incoming data and accurate direction of incoming vector f
transmitter to receiver. The image sensor technology will allow VLC to variou
applications which cant be realized by radio wave technology like indoor na
augmented reality, accurate control of robots or vehicles and accurate positi
measurement.
Working with LI-FI
Importance of using VLC:
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Devices which are used for transmission purpose in VLC are visible light LED
fluorescent lamp. LED light intensity is modulated by controlling its currenttechnology uses fluorescent lamps to transmit signals at 10bit/s, or LEDs fo
Mega bit/s. Devices which are used for reception purpose in visible light co
are pin photodiode (high speed reception up to 1Gbps), Avalanche photo d
sensitive reception) and Image sensor (simultaneous image acquisition and
reception).
Working with LI-FI
Device uses in VLC :
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Working with LI-FI
Examples :
(Devices used in Visible light communication)
Pin photo diode Avalanche photodiode Image Sanser
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Basically LI-FI product are construct in four parts:
1. Bulb
2. RF power amplifier circuit (PA)
3. PCB (printed circuit board)
4. Encloser
BULB
E
PA
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How LI-FI WorksWhen power source is connected to the RF deriver then it generate the radio
frequency which is amplified by the power amplifier and it is coupled with th
emitter assembly, so it generate light emitting plasma . Solid-State Power Am
used in the RF deriver to create and amplify the RF energy.Process of LI-FI working in steps:
An RF circuit is established by connecting an RF power amplifier to a ceram
resonant cavity known as the puck.
In the center of the puck is sealed quartz bulb that contains materials consiwith metal-halide lamps.
The puck, driven by the power amplifier, creates a standing wave confined w
walls.
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How LI-FI Works
The electric field is strongest at the center of the bulb which ionizes thegass
the bulb (purple glow).
The ionized gas in turn heats up and evaporates the metal-halide materials w
form a bright plasma column within the bulb (blue to bright white light).
This plasma column is centered with in the quartz envelope and radiates ligh
efficiently.
In the back side of the bulb, a highly reflective powder is used to reflect nea
this light in the forward direction.
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Assembly of RF circuit Emitting RF rays
Emitting plasma column
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Wide spectrum over the visible
Wavelength range extended.
High speed data transmission.
Extremely high color fidelity.
Instant start-time. Dynamic DarkBrightness modulation of lamp output to enhance video contrast.
Easy thermal management.
Trouble-free integration into existing light engine platforms.
The system has unique advantages in that it can be used in areas where radio
frequency is not desirable.
The system also benefits from an existing lighting infrastructure and therefore
does not require huge investments.
It also offers greater security by keeping the internet signal inside the room inwhich the light is being used.
Li-Fi was developed as an alternative to carrying data on radio frequencies, which
are becoming increasingly crowded with the growth in smartphone and tablet PC
use.
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It can be used in the places where it is difficult to lay the optical fiber like hospitals.
In operation theatre Li Fi can be used for modern medical instruments.
In traffic signals Li Fi can be used which will communicate with the LED lights of the
cars and accident numbers can be decreased.
Thousand and millions of streetlamps can be transferred to Li Fi lamps to transfer
data.
It can be used in petroleum or chemical plants where other transmission or
frequencies could be hazardous.
It can be used in offices to access and transfer the data from one to anotheremploy.
It can be used in e learning system to secure that the student cannot use other data
at the time of study.
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Common Myths of Li-Fi:
Uni-Directional Only. No. Li-Fi can be implemented as a transceiver , Providing both
transmission and reception.
Visible Light Essential. No. Li-Fi enabled LEDs can be dimmed until no light is
humanly visible, but data communications is still maintained reliably.
Line-Of-Sight Required. Nobut desired. Li-Fi is perfectly capable of data
communications from reflected light, but the signal will be stronger on direct light.
Requires Special LEDs. No.
Ch ll
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ChallengesCAN THIS TECHNOLOGY BE IMPLEMENTED?
Yes, this is already proven. Harald Haas demonstrated his invention using an
lamp that successfully transmitted data at speeds exceeding 10Mbps using ligLED light bulbs to a computer located below the lamp. To prove that the light
source of the data stream, he periodically blocked the beam of light , causing
to drop.
PROBLEM OF IMPLEMENTIG OF LI-FITo implement this technology it is suggested that the ordinary bulbs should b
the Li Fi lamps which will generate light emitting plasma. But initially availabl
the bigger size. So work on minimizing the size is started and now we have th
which can be used for generation of light signal.
Conclusion
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Conclusion
The possibilities are can be explored further. If his technology can be put in
practical use, every bulb can be used like a Wi-Fi hotspot to transmit wirel
Data and we will proceed toward the cleaner, greener, safer and brighter fu
The concept of Li-Fi is currently attracting a great deal of interest, not least
may offer a genuine and very efficient alternative to radio-based wireless.
This may solve issues such as the shortage of radio-frequency bandwidth
internet where traditional radio based wireless isnt allowed such
hospitals.
Reference
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Reference
[1] Baldev Singh, VIT campus, Jaipur LI-FI
[2] Chris Slinger, Colin Cameron , Maurice Stanley Computer-Wireless as a LI-FI ,IEEE computer soc53
[3] S. Sadhana Rao, Electronics and Communication engineering, Anna University of Technology, Lig
Proceedings of the International Conference on Communication and Computational Intelligence2
[4] Cristian Gadea, Bogdan Ionescu, Dan Ionescu, Shahidul Islam, Bogdan Solomon,University of Ott
Technologies New wireless Technology LI-FI 7th IEEE International Symposium on Applied May 24-
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Questions? More
Information?