In this paper, we propose a new modulation scheme called multi-coded variable pulse position modulation (MC-VPPM) for visible light communication systems. Two groups of signals (Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM) groups) are multi-coded by orthogonal codes for transmitting data simultaneously. Then, each multi-level value of the multi-coded signal is converted to pulse width and position which results in not only an improved data rate, but also a processing gain in reception. In addition, we introduce average duty ratio and cyclic shift concepts in PWM through which dimming control for light illumination can be supported without any degradation in communication performance. Through simulation, we confirm that the proposed MC-VPPM shows a comparable BER curve and much greater achievable data rate than the conventional VPPM scheme using a visible light optical channel environment.
© 2012 Optical Society of Korea
(060.4510) Fiber optics and optical communications : Optical communications
(230.3670) Optical devices : Light-emitting diodes
(060.2605) Fiber optics and optical communications : Free-space optical communication
Original Manuscript: January 2, 2012
Revised Manuscript: April 18, 2012
Manuscript Accepted: May 3, 2012
Published: June 25, 2012
Hyun-Dong Moon and Sung-Yoon Jung, "Multi-coded Variable PPM for High Data Rate Visible Light Communications," J. Opt. Soc. Korea 16, 107-114 (2012)
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