Illuminance distribution of LED spherical arrays is studied by theoretical analysis and simulation. The optimal
layout of the LED spherical array is founded by changing the angle, the ball radius, and the power of different LED.
The uniformity of illumination of the LED spherical array is verified, which is better than LED planar array. In
addition, the illuminance distribution of indoor ground surface illuminated by LED spherical array with different
parameters and the related curves are obtained. The LED spherical array mentioned in this paper can be useful in
the application of indoor visible light communication.
Trellis-coded pulse-amplitude modulation (TC-PAM) is applied in visible light communication (VLC) system using
RGB-LED. Based on natural modulation, we propose a modified modulation to yield performance enhancement. Further,
a decoding method of combing soft-decision Viterbi algorithm with most significant bit (MSB) decoding is developed.
Finally, the results of Monte-Carlo simulation are presented to verify the best modulation and decoding method among
the mentioned modulation and decoding techniques.