li-fi (ankit pandey)

8/13/2019 Li-fi (Ankit Pandey)

1/33

ANKIT KUMAR PANDEYM.TECH 2ND YEAR (ECE)

ROLL NO-4

J.K. INSTITUTE OF APPLIED PHYSICS & TECHNOLOGY

A.U. ALLAHABAD

Wireless communication through Light illumination

11/28/2013 1ankit pandey


2/33

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



3/33

The Li-Fi protocols are defined by the internationalstandard 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 theelectromagnetic spectrum to transmit information



4/33

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



5/33

.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.



6/33

Radio spectrum

1.4 Million base stations, 5 billion Mobile stations

600tb data every month



7/33

efficiency

availability

security

capacity


8/33

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



9/33

AVAILABILITY;

Available within the range of Base stations

Limited availability

Unavailable in aircrafts

SECURITY:

Less secure(passes through the walls)



10/33

Why only VLC can replace radio communication?



11/33

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 tinychanges in amplitude

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

1. Intensity can be modulated into very high speeds andvarying amplitudes

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



12/33

LI-FI product consists of four primary sub-

assemblies;

I. Bulb

II. RF power amplifier circuit

III. Printed circuit board(PCB)

IV. Enclosures



13/33

CONSTRUCTION

The PCB controls the electric inputs andoutputs of the lamp and houses.

A radio frequency signal is generated by the

solid state power amplifier and is guided intoan electric field about the bulb.



14/33

CONSTRUCTION

The high concentration of energy in the

electric field vaporizes the contents of the bulb

to a plasma state at the bulbs center, this

controlled plasma generates an intense sourceof light.

All of these subassemblies are contained in

an aluminum enclosure



15/33

PA

PCB

ENCLOSURES

BULB

LI-FI BLOCK DIAGRAM



16/33

At the heart of LIFI is the bulb sub-assembly where a

sealed bulb is embedded in a dielectric material.

bulb

Dielectric

material



17/33

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.



18/33

The operational procedure is very simple; if the LED

is on, you transmit a digital 1, if its off you transmit

a 0.

Vary the rate at which the LEDs 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.



19/33

DataModulation

(PPM/FSK)

Light

Source

Data

Demodulation

(PPM/FSK)

Photo

Detector



20/33

The receiver has optics, and is fast enough to see the

light dimming and brightening, smart enough todecode the Li-Fi data, and then deliver it to the

attached device such as a laptop computer.



21/33

WORKING OF LI-FI



22/33



23/33

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 lightData transfer rate 11 Mbps >1 Gbps

Security less secure highly secure



24/33

Larger bandwidth (10,000 times the radio

bandwidth)

High efficiency

More availability

Highly secure



25/33

Shadowing

Dimming

Multiuser support

Connectivity while moving



26/33



27/33



28/33



29/33



30/33


31/33

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 isnt allowed.



32/33

Http://en.wikipedia.org/wiki/Li-Fi

IJERT Vol. 2 Issue 10, October2013 ;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 ObjectIdentifier: 10.1109/CCNC.2011.5766491 2011 , Page(s): 362 -

364



33/33

11/28/2013ankit pandey 33

li-fi (ankit pandey)

Documents