Li-Fi (Light Fidelity)

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Light Fidelity (Li-Fi) TechnologyBy RAJASHEKAR VITTALEmail: [email protected]

INTRODUCTION

ELECTROMAGNETIC SPECTRUM?

ISSUES REGARDING RADIO SPECTRUM AND WHY VLC?

DEVICES USED

BASIC CONCEPTS AND WORKING OF LI-FI

COMPARISION BETWEEN LI-FI AND WI-FI

POTENTIAL APPLICATIONS

CHALLENGES FOR LI-FI

CONCLUSIONINTRODUCTION

LightFidelity (Li-Fi) is a technology that uses the Light Emitting Diodes (LEDs) to transmit the data wirelessly instead of radio waves.

Li-Fi technology came into existence in 2011.

This technology was invented by German physicist Harald Haas.

Researchers have reached data rates of over 500 megabytes per second using a standard white-light LED.

It allows wireless communication without the use of radio waves, which can be dangerous in places like oil platforms, underwater and on planes.

Li-Fi can be thought of as a light-based Wi-Fi.

Why VLC?(Visible Light for Communication)

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.

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.

Issues regarding Radio Spectrum. (Cont.)

Issues regarding the Radio SpectrumCapacity:With the increasing number of mobile connections the availability of the spectrum is getting congested.Radio waves form only a small fraction of the entire EM spectrum thus making the problem even worse.

Efficiency:For every unit of energy consumed the data transmitted is relatively less.The data speeds in the current system can only reach up to a few hundreds of megabits per second.

Security:These radio waves can easily penetrate through the walls, thus letting anonymous users to use the network.

Economic:Due to limited availability of the radio waves the tariff rates are relatively costlier. There can be many issues during the spectrum allocations.Hence we are left with only the VISIBLE - LIGHT SPECTRUM which is not harmful for humans.

DEVICES USED

Devices which are used for transmission purpose in VLC are visible light LEDs(up to 500 Mbit/s) or fluorescent lamp(10bit/s).

Devices used for reception purpose in VLC are photo diodes and image sensors.

Amplification and processing unit to amplify the signal.

BASIC CONCEPTS AND WORKING

LED ie Light emitting diode can be switched on and off faster since operating speed of LED is less than the human eye can detect, causing the light source to be appear continuously.

Switching the LEDs ON and OFF gives nice opportunities for transmitting data using binary codes 0 and 1.

A controller placed can code data into those LEDs.

Usage of an array of LEDs for parallel data transmission, or using mixtures of red, green and blue LEDs to alter the lights frequency.

On one end all the data on the internet will be streamed to a lamp driver when the led is turned on, the microchip controller converts the digital data in form of light through LEDs.

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

LI-FI has upper hand due to parallel data transmission.COMPARISION BETWEEN LI-FI AND WI-FISl.NoParametersLight FidelityWireless Fidelity1Speed for data transferFaster transfer speed (>1 Gbps)Data Transferspeed (150Mbps)2Medium throughwhich datatransfers occursUsed Light as a carrierUsed Radio spectrum3Spectrum RangeVisible light spectrum has 10,000time broadspectrum in comparison toradio frequencyRadio frequency spectrum rangeis lessthan visible light spectrum.4CostCheaper than Wi-Fi because freeband doesntneed license and it use light.Expensive in comparison toLi-Fibecauseits uses radio spectrum.5Network topologyPoint to pointPoint to point6Operating frequencyHundreds of TeraHz (THz)2.4GHzPOTENTIAL APPLICATIONS

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

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 overcomes this drawback on radioways , li-fi can be implemented.

Traffic lights can communicate to the car and with each other. Cars have LED-based headlights, LED-based cack lights, and cars can communicate with each other (using some alerts) and prevent accidents in by exchanging information.

CHALLENGES FOR LI-FI

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.

High installation cost of the VLC systemsCONCLUSION

If his technology can be put into practical use, every bulb can be used something like a Wi-Fi hotspot to transmit wireless data .

TheconceptofLi-Fiiscurrentlyattractinga great deal of interest very efficient alternative to radio-based wireless.

Researchers are developing micron sized LED in which case a 1000 micron LEDs can communicate as much information as a single LED given the same space.

This may solve issues such as the shortage of radio-frequency bandwidth and also allow internet where radio based wireless isnt allowed such as aircrafts or hospitals. THANK YOUBy: RAJASHEKAR VITTALEmail: [email protected]