Li fi technology - A complete overview

LI-FI (LIGHT FIDELITY) TECHNOLOGY

CONTENTSPresent Scenario IntroductionBasic ConceptsHow Li-Fi Works?Li-Fi ConstructionComparisonsAdvantagesLimitationsSolutions to problemsConclusion

Wireless data is growing exponentially…

YouTube In 2011, ~ 140 views for every person on earth

(over 1 Trillion views) 72 hours of video are uploaded to YouTube every

minute25% of global YouTube views come from mobile

devicesInternet video traffic is growing at 48% CAGR

…leading to RF Spectrum Shortage

Present Scenario

1.4 Million 5 Billion

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.

How to fix the problem?Identify new spectrum, orEnhance spectrum reuse (smaller cells), or Both measures jointly

WHO CAN REPLACERADIO WAVES FOR WIRELESSCOMMUNICATION ?

IntroductionLi-Fi is a VLC, visible light communication, technology

developed by a team of scientists including Dr. Gordon Povey, Prof. Harald Haas and Dr. Mostafa Afgani at the university of Edinburgh.

Li-Fi is now part of the Visible Light Communication (VLC) PAN IEEE 802.15.7 standard. “Li-Fi” is typically implemented using white LED light bulbs.

LI-FI is transmission of data through illumination ,sending data through a LED light bulb that varies in intensity faster than human eye can follow.

Why only VLC ?

Basic ConceptsLED i.e. Light emitting diode can be switched on and off faster

since operating speed of LED is less than 1 μs, than the human eye can detect, causing the light source to be appear continuously.

This invisible on-off activity enables a kind of data transmission using binary codes: switching on and LED is a logical ‘1’, switching it off is a logical ‘0’.

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

How Li-Fi Works?

Fig. : LIFI Block Diagram

The LI FI product consists of 4 primary sub-assemblies:• Bulb• RF power amplifier circuit (PA)• Printed circuit board (PCB)• Enclosure

Li-Fi Construction

bulb

Comparison with Wi-Fi

AdvantagesCapacityAvailabilityEfficiency

Easy To UseFast Data TransferHarmlessnessLow-cost

Limitations/Challenges

Light can't pass through solid objects, and thus

the signal may be lost

Connectivity while moving

Multiuser support

Dimming

Shadowing

Solutions to Challenging problems

Solution for connectivity The solution is called “handover”, using which the user is transferred from

one BS to another Handover is done in the area that two BS’s have common coverage The user can be transferred from one light source to another in the area that

is under the coverage of both

Contd.. Solution for multiuser support One solution is time division multiplexing (TDM) Each frame is divided into equal time slots Each user transmit data in one time slot in a predefined order The other solution is code division multiple access (CDMA) Codes are assigned to users Each user transmit its data using the assigned signature pattern It is used in 3G and 4G cellular networks

Contd..Solution for shadowing

As shown before, the impulse response in VLC systems has two parts When the line-of-sight (LOS) part (which is received via direct path) is

blocked, the impulse response is only the second part Then the data can be recovered using the second part which is indeed the

received data from the indirect paths (multipath signal)

Conclusion Li-Fi will make are lives more technology driven in the near future.

With its magic of light it can make our world a greener, safer, cleaner and moreover a brighter place to live.

Referenceshttp://en.wikipedia.org/wiki/Li-Fi http://teleinfobd.blogspot.in/2012/01/what-is-lifi.html technopits.blogspot.comtechnology.cgap.org/2012/01/

11/a-lifi-world/ www.lificonsortium.org/ the-gadgeteer.com/2011/08/29/li-fi-internet-at-the-

speed-of-light/ http://www.digplanet.com/wiki/Li-Fi Visible-light communication: Tripping the light

fantastic: A fast and cheap optical version of Wi-Fi is coming”, Economist, dated 28Jan 2012

Thank You All