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LI-FI

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AN INTRODUCTION

LI-FI

Light FidelityVisible Light Communication Light based wi-fiVisible light used instead of RF waves

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GENESIS OF LI-FI

DR. Herald Haas begins his research in 2004. Gives a breakthrough presentation on “TED TALKS”

in July 2011. Uses a table lamp with an LED bulb to transmit a

video of blooming flowers.

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HOW LI-FI WORKS

Implemented using white LED light bulbs at the downlink transmitter. By fast and subtle variations of the current, the optical output is made to

vary at extremely high speeds. The operational procedure is very simple-, if the LED is on, you transmit a

digital 1, if it’s off you transmit a 0. The LEDs can be switched on and off very quickly, which gives nice

opportunities for transmitting data. Further enhancements can be made in this method, like using an array of

LEDs for parallel data transmission.

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Linux Distributions

• Corel Linux

• Debian GNU/Linux

• OpenLinux (Caldera)

• Red Hat

• Slackware

• SuSE

• TurboLinux

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HOW IT WORKS ….(cont.)

To further get a grasp of Li-Fi consider an IR remote. It sends a single data stream of bits at the rate of

10,000-20,000 bps. Now replace the IR LED with a Light Box containing a

large LED array. This system is capable of sending thousands of such

streams at very fast rate.

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HOW IT WORKS …(cont.)

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WHY LI-FI

PRESENT SCENARIO IN WIRELESS COMMUNICATIONThere are 1.4 million cellular radio masts deployed worldwide. There are more than five billion wi-fi devices present.With all these devices, we transmit more than 600 terabytes of data every month.Wireless communications has become a utility like electricity and water.

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WHY LI-FI ….(cont.)ISSUES WITH WI-FI USING RADIO WAVES

1. CAPACITY

Radio waves are scarce, expensive and we only have a certain range of it. 

Due to this limitation one can’t forever hope to cope with the demand of wireless data transmissions

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WHY LI-FI ….(cont.)

2. EFFICIENCYThere are 1.4 million cellular radio masts deployed worldwide.Most of the energy consumed, is not used to transmit the radio waves, but is used to cool the base stations.

3. HEALTH ISSUES There are potential health issues associated with radio waves.

4. SECURITY The radio waves penetrate through walls. They can be intercepted, and somebody can make use of one’s

network.

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WHY LI-FI ….(cont.)

ALTERNATIVES TO RADIO WAVES IN EM SPECTRUM

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WHY LI-FI ….(cont.)

Gamma Rays can’t be used as they could be dangerous. X-Rays have similar health issues. Ultraviolet Light is good for a nice suntan, but otherwise

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

with low power.

Hence we are left with only the Visible Light Spectrum.

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LIGHT FOR WIRELESS COMMUNICATION

HOW LI-FI OVERCOMES ISSUES ATTACHED WITH RADIO WAVES :-

1.CAPACITY

We have 10,000 times more spectrum in visible light region than in the radio waves region.

Therefore we have 10,000 times more channels to transmit data.

2. EFFICIENCY

LED consumes very little power therefore the

data transmission is very efficient.

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LIGHT FOR WIRELESS COMMUNICATION

3. SAFETY Visible light poses no health issues.

4. SECURITY Light Waves doesn’t penetrate through walls.  Therefore they can’t be intercepted easily.

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POTENTIAL APPLICATIONS OF LI-FI

1. INTRINSICALLY SAFE ENVIRONMENTS

1. TRAFFIC LIGHTS

3. PUBLIC INTERNET HOTSPOT

4. ON OCEAN BEDS

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ADVANTAGES/DISADVATAGES OF LI-FI

ADVANTAGES

SUPERIORITY OVER RF WAVES LITTLE INFRASTRUCTURE REQUIREMENTS SIMPLE SYSTEM STRUCTURE

DISADVANTAGE

needs direct line of sight to transmit data.

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FUTURE

In 2009, the US Federal Communications Commission warned of a looming spectrum crisis: because our mobile devices are so data-hungry we will soon run out of radio-frequency bandwidth. Li-Fi could free up bandwidth, especially as much of the infrastructure is already in place.

The solution might be Li-Fi. Direct modulation of LED devices is a low cost, secure, and safe way to transmit data, and there is an abundance of free visible light spectrum.

At Heinrich Hertz Institute in Berlin, Germany researchers have achieved a data rate of 500 megabytes per second using a standard white LED. 

However everyone is not so optimistic. Dr Suresh Borkar , a trend-watcher, consultant and communications expert who teaches at the Illinois Institute of Technology, opines that at the current stage of maturity, Li-Fi usage will be limited to in-house and proximity applications. The use of very high frequency (400-800 THz) limits it to very short distances and more of point-to-point communications.

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CONCLUSION

The fact that Li-Fi is being considered as one of the IEEE 802.xx standards bodes well for its potential success.

However it has certain inherent limits for the technology.

LiFi may not be able to replace conventional radios altogether, but it can still change the wireless scenario.