Light-fiedility

ANKIT KUMAR PANDEY
M.TECH 2ND YEAR (ECE)
J.K. INSTITUTE OF APPLIED PHYSICS & TECHNOLOGY
A.U. ALLAHABAD
Wireless communication through Light illumination
7/2/2016 1ankit pandey

 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

 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

 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

 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

efficiency
availability
security
capacity

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

 LI-FI product consists of four primary sub-
assemblies;
I. Bulb
II. RF power amplifier circuit
III. Printed circuit board(PCB)
IV. Enclosures

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.
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.

Data
Modulation
(PPM/FSK)
Light
Source
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

• Larger bandwidth (10,000 times the radio
bandwidth)
• High efficiency
• More availability
• Highly secure

 Shadowing
 Dimming
 Multiuser support
 Connectivity while moving

 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.

 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

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