## 2 Proposed Communication System
### Overview of Proposed Communication System  
The proposed QCD-OCC system is divided into two parts, transmitter (Tx) and receiver (Rx), separated by a free space channel as shown in Figure 3. On the transmitter side, the data to be transmitted can be in two formats, where \((R,G,B)_{i=1}^{48}\) is an array of size 48 containing color information for the respective indices of three individual datastreams or a single one:  
* **Format 1:** In this format, three separate binary data streams, \(D1\), \(D2\), and \(D3\), of variable lengths for users \(U1\), \(U2\), and \(U3\) are used to generate a 3D matrix of size 1 \(\times\) 48 \(\times\) 3, as shown in Equation (2), where matrices \(R\), \(G\), and \(B\) are submatrices along the \(Z\) axis at Indices 1, 2, and 3, respectively. \[(R,G,B)_{i=1}^{48}=(D1_{i},D2_{i},D3_{i})\] \begin{table}
\begin{tabular}{c c c c} \hline
**Bits** & **Color** & **Bits** & **Color** \\ \hline
000 & \(\hat{\mathrm{R}}\hat{\mathrm{C}}\hat{\mathrm{B}}=\mathrm{Black}\) & \(111\) & RGB = White \\
001 & B = Blue & \(110\) & B = Yellow \\
010 & G = Green & \(101\) & \(\hat{\mathrm{C}}\) = Violet \\
100 & R = Red & \(011\) & \(\hat{\mathrm{R}}\) = Cyan \\ \hline \end{tabular}
\end{table} 
Table 1: Bits to color mapping using baryon additive color model. Figure 2: Gluon-exchange-based color changes in quarks, baryon model. * **Format 2:** in this format, a single binary data stream \(D\) is folded to obtain a 3D matrix of size 1 \(\times\) 48 \(\times\) 3, as shown in Equation (3). \[(R,G,B)_{i=1}^{48}=(D_{i},D_{48+i},D_{96+i})\] (3)  
Data representation in Format 1 enables MIMO and supports simultaneous communication with three users, while Format 2 provides 3\(\times\) bandwidth compared to Format 1, directed at one user. Format 1 is used throughout this paper for ease of understanding. Each matrix of size 1 \(\times\) 48 \(\times\) 3 obtained postmultiplexing is reshaped into corresponding 6 \(\times\) 8 \(\times\) 3 matrices. These 6 \(\times\) 8 \(\times\) 3 matrices are converted into 8 \(\times\) 8 \(\times\) 3 matrices by integrating anchor patterns. Anchor patterns are corner 2 \(\times\) 2 submatrices that retrieve orientation information from the image at the receiver side. The resultant 8 \(\times\) 8 \(\times\) 3 matrix is converted into an 8 \(\times\) 8 color image using bit color mapping as per Table 1. The color from each resultant cell is mapped onto LEDs on the basis of the color value and position in the matrix. An LED driver controls the status of LEDs as per the input from mapping, and produces an 8 \(\times\) 8 multicolor LED output. A continuous video capturing the transmitter LED panel is recorded on the receiver side. The video is processed frame by frame to extract the transmitter's position using the image processing technique. The detected region of interest (RoI) is resized and converted into an 8 \(\times\) 8 \(\times\) 3 image that undergoes channel separation and provides three 8 \(\times\) 8 binary matrices. The data are regenerated at the receiver side after the removal of anchor patterns. A simulator and prototype of the proposed QCD-OCC system were implemented, and their performance was evaluated. The performance of the system was evaluated on the basis of the peak signal-to-noise ratio (PSNR), data throughput, the success of reception (%), and bit-error rate (BER) at various distances and under different ambient lighting conditions. PSNR serves as a metric for evaluating channel quality. It is computed using the mean square error (MSE) between the images containing inactive Tx(\(I_{in}\)) and active Tx(\(I_{ac}\)) [26]. Equation (4) shows the computation of MSE, where _Rows_ and _Cols_ are the height and width of input images in terms of pixels, respectively. \[MSE(I_{in},I_{ac})=\frac{1}{Rows\times Cols}\sum_{i=1}^{Rows}\sum_{j=1}^{Cols}( I_{in}(i,j)-I_{ac}(i,j))^{2} \tag{4}\]  
Figure 3: Overview of proposed QCD–OCC system.