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 tothe communication technology which utilizes thevisible light source as a signal transmitter, the air asa transmission medium, and the appropriatephotodiode as a signal receiving component.
Visible light is the form in which electromagneticradiation with wavelengths in a particular range isinterpreted by the human brain. Visible light isthus by definition comprised of visually-perceivable electromagnetic waves. The visiblespectrum covers wave lengths from 380 nm to 750nm.
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
LED Modulation• Opto-electronic response V 0 Vd White response Rs L Blue response -5 I Cd Relative response (dB) SPICE Model Cs -10 Rs = 0.9727 L = 33.342 nH -15 Cs = 2.8 nF Cd = 2.567 nF tt = 1.09 ns -20 Luxeon LED -25 0 10 20 30 40 50 freq (MHz) Measured LED small-signal bandwidth
MODULATION:-•Pulse Position Modulation(PPM)•Frequency Shift Keying(FSK)
The Visible Light CommunicationsConsortium (VLCC) which is mainlycomprised of Japanese technology companieswas founded in November 2003. It promotesusage of visible light for data transmissionthrough public relations and tries to establishconsistent standards.
Research Advancement and Planning Committee Technical Committee Standardization Committee Popularization Committee
•Human Safety•High Data Rate•Bandwidth•Security•Visibility•Unlicensed Spectrum
•Limited Transmission Power•Regulated Spectrum:•Banned in Sensitive Areas
Limited Data Rates: In IR communications, data rates cannot beincreased beyond a prescribed level as itposes serious threat to human eyes. This canbe attributed to the high energy densitycreated by IrDA due to invisibility.
• Position Detection• Intelligent Super Mart• Intelligent Transport System• Image Sensor Communications• Networking• Audio Applications• Aesthetics
•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 efficiencyand affordability.