Light-fiedility

04/11/2023ankit pandey 1

ANKIT KUMAR PANDEY

M.TECH 2ND YEAR (ECE)

ROLL NO-4

J.K. INSTITUTE OF APPLIED PHYSICS & TECHNOLOGY

A.U. ALLAHABAD

Li-Fi ( Light Fidelity).Wireless communication through Light illumination


Introduction History Present Wireless Communication How LI-FI Construction of LI-FI How LI-FI works Comparison with WI-FI Advantages Disadvantages Applications Conclusion References

OUTLINE OF THE PRESENTATION


The Li-Fi protocols are defined by the international standard IEEE 802.15 established since 2011

Li-Fi refers to wireless communication systems using light as a medium instead of traditional radio frequencies, as in technology using the Wi-Fi.

The general term visible light communication (VLC) includes any use of the visible light portion of the electromagnetic spectrum to transmit information

INTRODUCTION;


The term Li-Fi was coined by Harald Haas from the University of Edinburgh in the UK in 2011.

In October 2011the Li-Fi Consortium group was formed to promote high-speed optical wireless systems.

VLC technology was exhibited in 2012 using Li-Fi

HISTORY;


.By August 2013, data rates of over 1.6 Gbps were demonstrated over a single colour 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, Fudan University, researchers modulated Internet signals to a 1watt LED lamp. Under the light, four computers were able to access the Internet.


Radio spectrum

1.4 Million base stations, 5 billion Mobile stations

600tb data every month

Present Wireless Communication

efficiency

availability

security

capacity

Issues regarding Radio spectrum;


CAPACITY(using radio waves)

Cost and Expensive Less Bandwidth compared to other spectrums Insufficient spectrum for increasing data

EFFICIENCY Millions of base-stations consume huge amount of

energy for 1.Transmitting the radio waves 2.To cool the base station cabins 5% Efficiency


AVAILABILITY;

Available within the range of Base stations Limited availability Unavailable in aircrafts

SECURITY: Less secure(passes through the walls)


Why only VLC can replace radio communication?


Normal light power is replaced by LED light power The LED bulb will hold a micro-chip that will do the job of

processing the data. The light intensity can be manipulated to send data by tiny

changes in amplitude

Properties of LED: (Fundamental property of LI-FI);

1. Intensity can be modulated into very high speeds and varying amplitudes

2. LED can be switched on and off with very high speed

How Li-Fi ?


LI-FI product consists of four primary subassemblies;

I. BulbII. RF power amplifier circuitIII. Printed circuit board(PCB)IV. Enclosures

CONSTRUCTION OF LI-FI


CONSTRUCTION…… The PCB controls the electric inputs and

outputs of the lamp and houses.

A radio frequency signal is generated by the solid state power amplifier and is guided into an electric field about the bulb.


CONSTRUCTION……

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


PA

PCB

ENCLOSURES

BULB

LI-FI BLOCK DIAGRAM


At the heart of LIFI is the bulb sub-assembly where a sealed bulb is embedded in a dielectric material.

FUNCTION OF THE BULB SUB-ASSEMBLY

bulb

Dielectric material


The dielectric material serves two purposes;

1. A waveguide for the RF energy transmitted by the power amplifier.

2. As an electric field concentrator that focuses energy in the bulb

The energy from the electric field rapidly heats the material in the bulb and emits light of high intensity and full spectrum.


The operational procedure is very simple; if the LED is on, you transmit a digital 1, if it’s off you transmit a 0.

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, using an array of LEDs for parallel data transmission. Such advancements promise a theoretical speed of 10 Gbps.

How LI-FI works?


Data

Modulation(PPM/

FSK)

Light

Source

Block Diagram (working)

Data Demodulation(PPM/FSK)

Photo

Detector


The receiver has optics, and is fast enough to ‘see’ the light dimming and brightening, smart enough to decode the Li-Fi data, and then deliver it to the attached device such as a laptop computer.


WORKING OF LI-FI



characteristics WI-FI LI-FI

Frequency 2.4 GHz to 5 GHz No freq is defined

Standard IEEE 802.11 IEEE 802.15

Range 100 meters Based on LED light

Data transfer rate 11 Mbps >1 Gbps

Security less secure highly secure

Comparison between Wi-Fi & Li-Fi


• Larger bandwidth (10,000 times the radio bandwidth)

• High efficiency• More availability• Highly secure

ADVANTAGES;


ShadowingDimmingMultiuser supportConnectivity while moving

DISADVANTAGES;







The possibilities are numerous and can be explored further. If this technology can be put into practical use, every bulb can be used something like a Li-Fi hotspot.

This may solve issues such as the shortage of RF bandwidth and also allow internet where traditional radio based wireless isn’t allowed.

CONCLUSION;


Http://en.wikipedia.org/wiki/Li-Fi IJERT Vol. 2 Issue 10, October – 2013 ;ISSN: 2278-0181 "pure VLC Ltd" (http://www.researchinnovation.ed.ac.uk/

Entrepreneurs/Enterpriseshowcase/pureVLCLtd).Enterprise showcase. University of Edinburgh.22 October 2013

Haas, Harald (July 2011). "Wireless data from every light bulb”.

An IEEE Standard for Visible Light Communications (http://visiblelightcomm.com/an-ieee-standard-forvisible- light-communications/) visiblelightcomm.com, April 2011.

Consumer Communications and Networking Conference (CCNC), 2011 IEEE Digital Object Identifier: 10.1109/CCNC.2011.5766491 2011 , Page(s): 362 - 364

REFERENCES ;

http://www.research/

http://www.research/

http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=5762824

http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=5762824

http://dx.doi.org/10.1109/CCNC.2011.5766491


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