Li-Fi TECHNOLOGY

Introduction History Technology Present Scenario Radio spectrum Issues of radio spectrum Electromagnetic spectrum Why VLC only Light-fidelity Working process How it works Comparison between WI-FI & LI-FI Applications of Li-Fi Limitations or Challenges Conclusion

Content

Light Fidelity (Li-Fi) is a bidirectional, high speed and fully

networked wireless communication technology similar to Wi-Fi.

The term was coined by Harald Haas and is a form of visible light

communication and a subset of optical wireless

communications (OWC) and could be a complement to RF

communication (Wi-Fi or Cellular network), or even a replacement

in contexts of data broadcasting. It is so far measured to be

about 100 times faster than some Wi-Fi implementations,

reaching speeds of 224 gigabits per second.

It is wireless and uses visible light communication or infra-red

and near ultraviolet (instead of radio frequency waves) spectrum,

part of optical wireless communications technology, which carries

much more information, and has been proposed as a solution to

the RF-bandwidth limitations.

Introduction

Harald Haas, who teaches at the University of Edinburgh in the UK, coined the term "Li-Fi" at his TED Global Talk where he introduced the idea of "Wireless data from every light". He is Chair of Mobile Communications at the University of Edinburgh and co-founder of pure Li-Fi.

The general term visible light communication (VLC), whose history dates back to the 1880s, includes any use of the visible light portion of the electromagnetic spectrum to transmit information. The D-Light project at Edinburgh's Institute for Digital Communications was funded from January 2010 to January 2012. Haas promoted this technology in his 2011 TED Global talk and helped start a company to market it. Pure Li-Fi, formerly pure VLC, is an original equipment manufacturer (OEM) firm set up to commercialize Li-Fi products for integration with existing LED-lighting systems.

In October 2011, companies and industry groups formed the Li-Fi Consortium, to promote high-speed optical wireless systems and to overcome the limited amount of radio-based wireless spectrum available by exploiting a completely different part of the electromagnetic spectrum.

A number of companies offer uni-directional VLC products, which is not the same as Li-Fi - a term defined by the IEEE 802.15.7 standardization committee.

VLC technology was exhibited in 2012 using Li-Fi. By August 2013, data rates of over 1.6 Gbit/s 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, it was reported Chinese manufacturers were working on Li-Fi development kits.

In April 2014, the Russian company Stins Coman announced the development of a Li-Fi wireless local network called Beam Caster. Their current module transfers data at 1.25 gigabytes per second but they foresee boosting speeds up to 5 GB/second in the near future. In 2014 a new record was established by Sisoft (a Mexican company) that was able to transfer data at speeds of up to 10 GBPS across a light spectrum emitted by LED lamps.

History of Li-Fi

Visible light communications (VLC) works by switching the current to the LEDs off and on at a very high rate, too quick to be noticed by the human eye. Although Li-Fi LEDs would have to be kept on to transmit data, they could be dimmed to below human visibility while still emitting enough light to carry data.

Technology

Radio Spectrum is congested but the demand for wireless data double each year. Every thing, it seems want to use wireless data but the capacity is drying up.

Present Scenario

1.4 Million Base Stations

5 Billion

Issues regarding Radio Spectrum

Radio Spectrum

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

Radio Spectrum Issues Capacity

Efficiency Millions of base stations consume huge amount of

energy for 1. Transmitting the radio waves2. To cool the base station cabins

5% Efficiency

Less secure(passes through the walls)

Radio Spectrum Issues

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

Security

Gama rays cant be used as they could be dangerous. X-rays have similar health issues. Ultraviolet light is good for place without people, but other wise

dangerous for the human body. Infrared, due to eye safety regulation, can only be used with low

power.

HENCE WE LEFT WITH THE ONLY THE VISIBLE - LIGHT SPECTRUM.

Why only VLCRadio

Waves Infrared

RaysVisible Rays

Ultraviolet Rays X- Rays

Gama Rays

WHO CAN REPLACE

RADIO WAVES FOR WIRELESS

COMMUNICATION ?

Light - Fidelity

Operational procedure is very simple, if the led is on, you transmit a

digital 1, if its off you transmit a 0. The LEDs can be switched on and

off very quickly, which gives nice opportunities for transmitting data.

Hence all that us required is some LEDs and a controller that code data

into those LEDs. We have to just vary the rate at which the LED’s .

Flicker depending upon the data we want to encode .

Thus every light source will works as a hub for data transmission .

Working Process

On one end all the data on the internet will be streamed to a

lamp driver when the led is turned on the microchip converts the

digital data in form of light .

A light sensitive device (photo detector) receives the signal and

converts it back into original data. This method of using rapid

pulses of light to transmit information wirelessly is technically

referred as Visible Light Communication .

How Li-Fi Works ?

Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light

instead of radio waves to transmit information.

Instead of Wi-Fi modems, Li-Fi would use trans receiver-fitted LED lamps

that can light a room as well as transmit and receive information.

WI-FI is great for general wireless coverage within buildings, and Li-Fi is

ideal for high density wireless data coverage in confined area and for

relieving radio interference issues .

So the two technologies can be considered complimentary.

Comparison between Li-Fi and Wi-Fi

Li-Fi vs Wi-Fi

Li Fi technology is still in its infancy .However some areas where it seems perfectly applicable are:-

Application Areas

Traffic Lights :

Traffic lights can

communicate to the car and

with each other. Cars have

LED-based headlights, LED-

based back lights, and cars

can communicate with each

other and prevent accidents

in by exchanging

information.

Visible Light is more safe than RF, hence it can be used in places where RF can't be used such as petrochemical plants .

Application of Li-Fi Intrinsically Safe Environment :

Hospitals (In Few Medical Equipmentes) :

Application of Li-Fi

Whenever we travel through airways we face the problem in communication media, because the whole airways communication are performed on the basis of radio waves. To overcome this drawback on radio ways, li-fi is introduced.

Application of Li-Fi

Li-Fi can even work underwater where Wi-Fi fails completely, thereby throwing open endless opportunities for military/navigation operations.

Application of Li-Fi On Ocean Beds :

There are millions of street lamps deployed around the world.

Each of these street lamps could be a free access point.

Application Street Lamps (As free Access

Points) :

Light can't pass through objects.

Interferences from external light sources like sun light, normal

bulbs, and opaque materials in the path of transmission will cause

interruption in the communication.

Li-Fi requires line of sight.

A major challenge facing Li-Fi is how the receiving device will

transmit back to transmitter.

Limitations or Challenges

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.

Conclusion

References www.nasa.gov/science/toolbox/emspectrum1.html

http://missionscience.nasa.gov/

http://www.ted.com/talks/harald_haas_wireless_data_from_every_light_bulb

http://gimt.edu.in/clientFiles/FILE_REPO/2012/NOV/23/1353645362045/69.pdf (E-Book)

http://ids.nic.in/technical_letter/Tnl_Jan2014/LI-FI%20(Light%20Fidelity)-The%20Future

%20Technology.pdf (E-Book)

http://www.lifi.eng.ed.ac.uk/lifi-news/2016-01-07-0734/what-lifi

http://www.homepages.ed.ac.uk/hxh/Li-Fi_PAPERS/what_is_LiFi_invited_ jlt_ecoc15.pdf (E-

Book)

http://purelifi.com/

http://www.ijirae.com/volumes/Vol2/iss6/01.JNAE10083.pdf

http://newtecharticles.com/new-li-fi-technology-to-access-internet/