LiFi technology (visible light communication )

by

BRIJESH BHARTI

(CIT-06/16)

Under the supervision of

Dr. Gausia Qazi

Department of Electronics & Communication EngineeringNational Institute of Technology,

Srinagar

(Visible Light Communication)

126/07/2017 National Institute of Technology, Srinagar

LiFi Technology

Outline Introduction

How it’s Works

The History of Li-Fi

Implementation of Li-Fi.

Comparison between Li-Fi / Wi-Fi

Currently Research progress 2017

Further research in the field can look into issue in LiFi

Present Standardization activities in LiFi

Features Advancement

Application of Li-Fi

Limitations of Li-Fi

Conclusion

References

202/05/2017 National Institute of Technology, Srinagar

Introduction

Li-Fi basically known as Light fidelity is an outcome of twenty first century

Li-Fi technology is a wireless communication system based on the use ofvisible light between 400 to 800 THz .[1}

02/05/2017National Institute of Technology, Srinagar

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How it’s Works

Li-Fi is a Visible Light Communications (VLC) system for data transmission

The working procedure is very simple,

if the light is on then transmit a digital “1”.if it’s off transmit a ‘’0’’. [2]

The LEDs can be switched on and off very quickly which gives nice opportunities for transmitting data.


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The History of Li-Fi Alexander Graham Bell is most famous for inventing the telephone, but he also

demonstrated the first VLC system in 1880. [3]


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The History of Li-Fiin 2003,

a team at the Nakagawa Laboratory located at Keio University in Japan used LEDs to transmit

data via visible light [12]. This is the first account of transmitting digital information via LEDs.

In 2010,

Heinrich Hertz Institute in Berlin .were able to transmit at a speed of 500 Mbit/s over a distance of

5 meters and transfer at 100 Mbit/s over an even longer distance with 5 white LEDs.[13]

In 2011,

at TED Global, there was a demonstration of the D-light project, a VLC project led by Harald Haas,

a professor at the University of Edinburgh [14]. The demonstration showed a HD video being

transmitted from a standard LED lamp. The data rate of the VLC system was approximately 10

Mbps


Li-Fi is typically implemented using white LED light bulbs at the downlink transmitter. These devices are normally used for illumination only by applying a constant current

by fast variations of the current, the optical output can be made to vary at extremely high speeds. This very property of optical current is used in Li - Fisetup


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Implementation of Li-Fi.


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Comparison between Li-Fi / Wi-Fi

Parameters Light Fidelity Wireless Fidelity

Speed for data transfer Faster transfer speed (>1Gbps)

Data transfer speed (150Mbps)

Medium through which data transfer occurs

Spectrum Range

Use Light as carrier

Visible light spectrum has 10,000 times broad spectrum in comparison to radio frequency

Use Radio spectrum

Radio frequency spectrum range is less than visible light spectrum

Cost Cheaper than Wi-Fi because free band doesn’t need license and it uses light

Expensive in comparison to Li-Fi because it uses radio spectrum

Network topology Point to point Point to point

Operating frequency Hundreds of Tera Hz 2.4GHz

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Currently, the University of Edinburgh UK is immersed in researching Li-Fi to solve many of the problems,[4]

The university has achieved 10 Gbps speed and also demonstrated that line of sight may not be a necessity for Li-Fi transmission. Research is underway on wireless system concepts based on Li-Fi. The university website lists the following projects currently in progress:[5]

Currently Research progress 2017

Currently Research progress 2017 Optical Multiuser MIMO

Interference Management in Cellular

The Internet of Things

Li-Fi Spatial Modulation

Digital Modulation OFDM

Self-Powered Li-Fi


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Further research in the field can look into issue in LiFi

Further research in the field can look into the following issues[6]

1) Driving illumination grade LEDs at high speed

2) Increasing data rate with parallelism/arrays

3) Achieving low complexity/low cost modulation

4) Overcoming the line of sight constraint

5) Achieving seamless interoperability with other networks

6) Making Li-Fi work in environments with little or no light


Present Standardization activities in LiFi JEITA (Japan Electronics and Information Technology Industries Association)

accepted these standards as JEITA CP-1221 and JEITA CP-1222 [21]

Standardization efforts for physical and media access layer are also done by IEEE 802.15, Task Group 7

In IEEE, 802.15 in IEEE 802 LMSC (LAN/MAN Standards Committee) has organized the study group on VLC and the group is now the task group 7 (TG7) (TGVLC website). In South Korea, the telecommunications technology association (TTA) (TTA website)

In Europe, the working group 5 of the wireless world research forum (WWRF) deals with VLC technology as one of next-generation wireless access technology.


Li-Fi offers a number of key benefits over Wi-Fi but is inherently acomplementary technology

Capacity

Bandwidth:

The visible light spectrum is plentiful (10,000 more than RF spectrum), unlicensed and free to use. [42]

Data density:

Li-Fi can achieve about 1000 times the data density of Wi-Fi because visible light can be well contained in a tight illumination area whereas RF tends to spread out and cause interference. [43]

High speed:

Very high data rates can be achieved due to low interference, high device bandwidths and high intensity optical output

FPGA


Features of Li Fi technology

Features of Li Fi technology

Efficiency Energy:

LED illumination is already efficient and the data transmission requires negligible additional power.

Environment:

RF transmission and propagation in water is extremely difficult but Li-Fi works well in this environment. Safety:

There are no known safety or health concerns for this technology.

Non-hazardous:

The transmission of light avoids the use of radio frequencies which can dangerously interfere with electronic circuitry in certain environments. Security


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• Spectrum Relief:

• Mobile Connectivity:

• Hazardous Environments;

• Underwater Communications:

• traffic management:

• super fast internet

• Aircraft

• Helth and technology

• Application in sensitive areas


Application of Li-Fi

Limitations of Li-Fi

The main problem is that light can’t pass through objects, so if the receiver is inadvertently blocked in any way, then the signal will immediately cut out[7]

Reliability and network coverage are the major issues to be considered by the companies while providing VLC services.

Interference from external light sources like sun light, normal bulbs; and opaque materials in the path of transmission will cause interruption in the communication

We can’t have a light bulb that provides data to a high-speed moving object or to provide data in a remote area where there are trees and walls and obstacles behind[8]


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Conclusion

“ 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 Wi-Fi hotspots to transmit wireless data”


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References

[1] https://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html

[2] www.techworld.com/data/what-is-li-fi-everything-you-need-know-3632764/

[3] [4] [5] https://www.engadget.com/2013/10/29/researchers-report-10gbps-data-

transmission-with-visible-led-lig/ /

http://www.techthefuture.com/technology/using-visible-light-frequencies-for-wireless-

data-transfer//

[6] http://www.ted.com/talks/harald_haas_wireless_data_from_every_light_bulb

[7] [8]

https://technozip.wordpress.com/technology/li-fi-technology/

LiFi study center , http://visiblelightcomm.com// lifi.eng.ed.ac.uk


2102/05/2017 Indian Institute of Technology Kharagpur

Thank You