Abstract: Simultaneous dimming controlling
and data transmission are usually required
in a white LED based indoor visible light
communication system. However, the diming
controlling of LED normally interferes the
data transmission due to the modulation
nonlinearity of LED. In order to solve this
problem, a scheme by separating the LEDs
for the functions of dimming control and
data transmission respectively is proposed
in this paper. In the scheme, the LEDs used
for dimming control function are driven
by a dc amplified circuit, and the LEDs for
data transmission are driven by a digital
modulation circuit respectively. In this way,
the modulation distortion to the data signal
caused by the modulation nonlinearity can
be avoided even if the dimming is at high
level dc driven current. The proof-of-concept
experiment of a 2.5Mbit/s visible light
communication system demonstrates that the
dimming controlling and data transmission can
be realized simultaneously in a simple way,
and the data transmission is not affected by
the dimming controlling function. Compared
to previous methods, the scheme in this paper
is simpler and cost effective, and makes sense
when high rate data is transmitted in a visible
light communication system