Modulations for Visible Light Communications With Dimming Control

Visible light communication (VLC) uses solid-state lightings to transmit information; therefore, it is necessary that modulation schemes for VLC provide dimming control. In this letter, we propose a multiple pulse position modulation (MPPM) to offer both functions of modulating data-stream and controlling the brightness at the same time. According to the dimming level, we control the number of pulses of MPPM in one symbol duration. We analyze communication performance in terms of the normalized power requirement and spectral efficiency. From our studies, we show that MPPM is superior to variable on-off keying (VOOK) and variable pulse position modulation (VPPM) proposed in the IEEE 802.15 VLC task group.