Theoretical Analysis of Equal-Weight (2, 2) VSS on VN-CSK Illumination Light Communication

On illumination light communications, the optical-wireless transmission scheme, which combines the visual secret sharing (VSS) scheme with the variable N-parallel code-shift-keying (VN-CSK) system, has been proposed. In this paper, the error rate performances of VSS data and two specified message data is theoretical analyzed under the general condition in which the distance from one lighting apparatus is not equal with the distance from another lighting apparatus. The relationship between the error rate and the receiver position is clarified when SNR on the receiver position (length, width, height) = (2.5,2.5,0.85) [m] is 15[dB] and the dimming level $N=1$. The optimum receiver position is (2.5, 2.5, 0.85), and then BER of VSS data achieves 4.0×10−3. It is found that SNR more than 20[dB] is necessary to provide a practical use of VSS data. On the other hand, BER of the message data from LED#1 becomes a minimum value when the receiver position is (1.25,2.5,0.85). Therefore, BER of the message data is considerably superior to that of VSS data.