## 4 Experimental Setup and Results  
Table 2 shows the parameters and their corresponding values used during the performance evaluation of the proposed system. Preliminary experiments were conducted to study the impact of distance on the pixel intensity of Tx. Figure 10a-c shows the original Tx, and its corresponding side and top views of intensity profiles at distances of 50, 100, and 200 cm, respectively. As shown in Figure 10a,b, for L = 50 and 100 cm, there was the least significant difference with respect to pixel density in the RoI. Intensities for white, red, and yellow LEDs were also more prominent across three images. Colors such as blue, green, and cyan had comparatively less intensity. Figure 10c shows that, for L = 200 cm, the intensity of cyan became negligible, resulting in faulty decoding of bits. The success of reception at a distance of 50 cm for varying Tx data rates was evaluated for the proposed QCD-OCC simulator and proposed QCD-OCC prototype. The magnification factor for the simulated Tx was kept at 0.9 to match the size of the prototype Tx at a 50 cm distance. The ambient light intensity for the prototype was \(\approx\)27-31 Lux. The mean of 10 iterations per data rate was used to generate a comparison. Figure 11 shows the obtained results.The success of the reception of the proposed QCD-OCC prototype drastically dropped after the point when the Tx frame rate became greater than 15. This was mainly due to sampling error that resulted in capturing Tx images during frame transitions. Since the proposed equation used for the simulation of the frame drop did not separately handle the condition of Tx data rate \(>fps/2\), the figure shows a linear drop in the success of the reception. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Value** & **Parameter** & **Value** \\ \hline Tx dimension & 6.5 \(\times\) 6.5 cm & CPU & i7-700 3.6 GHz \\ Tx model & WS2812B-64 \(8\times 8\) & & RAM & 16 GB \\  & LED Matrix & & \\ Transmission & 720, 1440, & & File sizes & File 1: 97 bytes \\ Data rates & 2160, 2880, & & File 2: 123 bytes \\  & 3600, 4320 bps & & File 3: 109 bytes \\ Camera & 30 fps \(1/1500\)s & Distances & 50, 100, \\ Frame rate & & & 150, 200 cm \\ Camera & 1920 \(\times\) 1080 pixels & Ambient light & 27, 149, \\ Resolution & & & 304 lux \\ Exposure & ISO100 & Rotation angle & 0, 45, 90 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameters of the experimental setup. Figure 9: Implemented QCD-OCC prototype system. Figure 11: Comparison of success of reception (%) between implemented proposed QCD–OCC simulator and proposed QCD–OCC prototype. Figure 10: Tx intensity profile at distances L = 50, 100, and 200 cm. The results of the evaluation of PSNR under various lighting conditions are shown in Figure 12a. With the increase in distance, the PSNR value decreased irrespective of lighting conditions. The PSNR value was also highest for the least ambient light intensity and gradually reduced with the increase in ambient light intensity. As distance and ambient light intensity increased, the difference between the reference and Tx images decreased directly proportionally to PSNR. Figure 12b shows the success of reception at various distances under different lighting conditions. The average of 10 samples per distance per lighting condition is plotted. For ambient light of \(\approx\)27 Lux, reception success was \(\approx\)100% at distances of 50, 100, 150, and 200 cm. The success rate gradually decreased with the increase in ambient light and distance. These results show that the proposed system performs well under low-light conditions. The BER of the proposed prototype was evaluated under the low-light condition of \(\approx\)27-30 Lux at distances of 50, 100, 150, and 200 cm for Tx data rates of 720, 1440, 2160, 2880, 3600, and 4320 bps. As shown in Figure 13a, the proposed system delivered its minimal BER of \(1.37\times 10^{-5}\) at a distance of 50 cm and Tx data rate of 720 bps.