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Visible Light Communication
Transcript of Visible Light Communication
Communication White Light LED Complex Modulation Method 600 TB/month PPM: Pulse Position Modulation
FSK: Frequency Shift Keying
OFDM: Orthogonal Frequency
Division Multiplexing 1.4 million 5 billion Capacity Efficiency Availability Security Electromagnetic Spectrum Comparison General Lightning Solution Incandescent bulb
First industrial light source
5% light, 95% heat
Few thousand hours of life Fluorescent lamp
10,000s hours Solid-state light emitting diode (LED)
More than 50,000 hours lifespan New technology, expensive and short life time. It is, however, very potential Popular for today general lighting, efficient and cheap Well-known technology, limited use, problem with balancing each R, G, B component to create white light RGB Blue Chip+Phosphor OLED VLC Transciever In an OFDM system, a high data rate serial data stream is split up into a set of low rate sub-streams
The parallel data transmission offers possibilities for alleviating problem of intersymbol interference (ISI) in serial comm.
The total channel bandwidth is divided into a number of orthogonal frequency subchannels. Applications Under water communications System Indoor broadcasting system. Inside Airplane Communication Vehicle to vehicle messaging Thank You Q n A Presented By:
Jitender Yadav PPM: Pulse Position Modulation Pulse-position modulation of the data 1, 0, 1, 0,0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1 is modulated into a succession of pulses with SC-4PPM and SC-2PPM. Frequency Shift Keying In FSK data is represented by varying the frequency of carrier wave. OFDM VLC Standards JEITA CP-1221 Japan Electronics and Information Technology Industries Association Restricts the wave length of all emitted light to be within a range of 380 nm to 750 nm
Suggests using Sub Carrier - Pulse Modulation
Defines three major frequency ranges
15 kHz to 40 kHz
40 kHz to 1 MHz
> 1 MHz Japan Electronics and Information Technology Industries Association JEITA CP-1222 Supposed to be used only for communication purposes
Restricts the sub carrier frequency to 28.8 kHz
Suggests using Sub Carrier - 4 PPM as Modulation Scheme IEEE 802.15 TG7 The IEEE has formed Task Group 7 which is supposed to write a PHY and MAC standard for VLC
Physical Layer (PHY) defines the electrical and physical specifications for devices
Media Access Control (MAC) data communication protocol sub-layer provides addressing and channel access control mechanisms LOCALISATION Can be used for estimating one's loction
Proposes a scenario for Visually Challenged people Radio waves do not propagate for a long distance under water It is demonstrated that the flashlight visible light transmitter was able to transmit signals for 30 meter distance