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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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