VISIBLE LIGHT COMMUNICATION

CONTENTS

What is VLC Visible light & Spectrum Indoor VLC scenario History VLC process -Transmitter -Receiver -Modulation VLCC VLC characteristics Comparison with RF & IR Demerits of VLC Applications

What is VLC..???

The visible light communication (VLC) refers to the communication technology which utilizes the visible light source as a signal transmitter, the air as a transmission medium, and the appropriate photodiode as a signal receiving component. 

Visible Light :-

Visible light is the form in which electromagnetic radiation with wavelengths in a particular range is interpreted by the human brain. Visible light is thus by definition comprised of visually-perceivable electromagnetic waves. The visible spectrum covers wave lengths from 380 nm to 750 nm.

Visible Light Spectrum

History of VLC

VLC Researches

First research can be traced to as early as 1998-1999

Contribution addressing broadband VLC using WLED started appearing in 2001

Visible Light Communication Consortium (VLCC) was established in November 2003

WWRF showed a few more contributions between 2000 and 2006

VISIBLE LIGHT COMMUNICATION PROCESS

Transmitters:-

•LED

•Fluorescent Light

LED Technical Evolution

LED Modulation

• Opto-electronic response

0 10 20 30 40 50-25

-20

-15

-10

-5

0

freq ( MHz)

Rel

ativ

e re

spon

se (

dB)

White response

Blue response

Measured LED small-signal bandwidth

sR dVL

sC

dC

V

I

Luxeon LED

Rs = 0.9727 L = 33.342 nHCs = 2.8 nFCd = 2.567 nFtt = 1.09 ns

SPICE Model

Receiver:-

•Photodiode

MODULATION:-

•Pulse Position Modulation(PPM)

•Frequency Shift Keying(FSK)

Indoor VLC Scenario

VISIBLE LIGHT COMMUNICATIONS

CONSORTIUM(VLCC)

The Visible Light Communications Consortium (VLCC) which is mainly comprised of Japanese technology companies was founded in November 2003. It promotes usage of visible light for data transmission through public relations and tries to establish consistent standards.

4 Different Committees Of VLCC`

Research Advancement and Planning Committee

Technical CommitteeStandardization CommitteePopularization Committee

VLC CHARACTERISTICS

•Human Safety•High Data Rate•Bandwidth•Security•Visibility•Unlicensed Spectrum

VLC vs RF Communication

•Limited Transmission Power•Regulated Spectrum:•Banned in Sensitive Areas

VLC vs IR Communication

Limited Data Rates: In IR communications, data rates cannot be increased beyond a prescribed level as it poses serious threat to human eyes. This can be attributed to the high energy density created by IrDA due to invisibility.

Demerits of VLC:-

•LOS Communication

•Short Range

Applications of VLC

• Position Detection• Intelligent Super Mart• Intelligent Transport System• Image Sensor Communications• Networking• Audio Applications• Aesthetics

CONCLUSION

•LED can be used not only for lighting thehomes but also as means for wireless in-house communication.

• VLC can create a revolution in the area ofconsumer networking because of efficiency and affordability.