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WELCOME

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SEMINAR ON

LI-FI

PRESENTED BY

PARVATHY S M BTECH ECE 7TH SEM

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WHAT IS LI-FI?The term Li-Fi was coined by Prof. Harald Haas during his TED

Global talk .

It  is a bidirectional, high speed and fully networked wireless communications similar to Wi-Fi.

Li-Fi is a subset of optical wireless communication.

Optical version of Wi-Fi.

Li-Fi is based on Visual Light Communication(VLC).

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Working Of Li-FiIts working is much simply explained as follows :

If the LED is on ,the digital 1 is transmitted

And if it is off ,the digital 0 is transmitted.

It is possible to encode the data in the light by varying the rate at which the LEDs flicker on and off to give different strings of 1s and 0s

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Cont’d…Due to the increasing demand for wireless data

communication the available radio spectrum below 10GHz has become insufficient.

The wireless communication industry has responded to this challenge by considering the radio spectrum above 10 GHz

According to Friis free space equation as frequency (f), increases the path loss (L) also increases.

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Cont’d…LiFi is a natural continuation of the trend to move to

higher frequencies in the electromagnetic spectrum.

LiFi could be classified as nm-wave communication.

LiFi uses LEDs for high speed communication

Able to provide speed of over 3 Gbps from a single micro LED

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Concept of attocellsThe optical Access Point(AP) in Li-Fi is referred to as an

attocell.

The Li-Flame ceiling unit connects to an LED light to form an atto-cell, which provides communication in the LED Light illuminated area.

If we equip a room with multiple light and that each light function as a very small radio base station, the result is a network of very small cells that is known as ‘optical atto cells’.

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Cont’d…As attocells operates in the visible light spectrum, the

optical attocell does not interfere with the macro cellular network.

Li-Fi attocells allow for extremely dense bandwidth reuse due to the inherent properties of light waves.

The coverage of each single attocell is very limited, and walls prevent the system from suffering from cochannel interference.

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Cont’d…Each atto cellular AP results in co-channel interference

reduction.

This technique allows the cellular coverage area to be broken down further into areas of low interference and areas of high interference.

A similar concept realized at the receiver side where

multiple receiver elements provide a means for enhanced interference mitigation capabilities.

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Cont’d…Due to the requirement for illumination indoors, the

infrastructure already exists, and this type of cell deployment results in the very high, practically interference-free bandwidth reuse.

The user data rate in attocell networks can be improved by up to three orders of magnitude.

Moreover, Li-Fi attocells can be deployed as part of a heterogeneous VLC-RF network.

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Modelling LiFi NetworksIn a LiFi attocell network, the placement of the APs affects the

system performance.

The light signal from a neighbouring AP causes interference which limits the signal-to-interference-plus –noise ratio (SINR).

The bandwidth can be shared among different optical APs according to the well-known frequency reuse concept.

The placement of the optical APs is mainly determined by the lighting design.

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Cont’d…Optical attocell networks exploit the ability of LiFi to

achieve a massive spatial reuse.

To demonstrate the high data density achieved by an optical attocell system, the area data rate, sarea, is used, and this is defined as:

sarea =s/Acell.

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APPLICATIONS OF

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Future of Li-FiIn November 2014, Li-Fi pioneers pure LiFi joined forces with

French lighting company Lucibel aiming to bring out Li-Fi enables products, by the end of 2016.

Li-Fi is reportedly being tested in Dubai, by UAE-based telecommunications provider and claims to have successfully provided internet, audio and video streaming over a Li-Fi connection

Reports suggest that Apple may build future iPhones with Li-Fi capabilities.

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References

http://ieeexplore.ieee.org/http://www.ijstr.org/final-print/oct2014/Li-f

i-A-New-Era-Of-Wireless-Communication-Data-Sharing.pdf

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