# Three-Dimensional Division of Visible Light Communication Irradiation Area
## 3 Theoretical Simulation and Analysis of VLC
### Simulation Results and Analysis  
After analyzing the VLC model, we conducted a comparative analysis of various parameters that affect the communication performance based on the parameter settings in Table 1. Figure 3 shows the simulation results. \begin{table}
\begin{tabular}{l l} \hline
**Parameters** & **Values** \\ \hline Transmitter half angle (\({}^{\circ}\)) & 60 \\ \hline Irradiance half angle at detector (\({}^{\circ}\)) & 20 \\ \hline Irradiance half angle at source (\({}^{\circ}\)) & 20 \\ \hline Communication distance (m) & 1 \\ \hline Detection surface area (cm\({}^{2}\)) & 1 \\ \hline \end{tabular}
\end{table} 
Table 1: The simulation parameters. Figure 2: Simulation diagram. In Figure 3a, according to \(\Psi_{c}\)\(\leq\)\(\pi\)/2 in Formula (1), the transmitter half angle is set to vary from \(0^{\circ}\) to \(80^{\circ}\), with an interval of \(2^{\circ}\), and the irradiance half angle at the source varies from \(10^{\circ}\) to \(50^{\circ}\), with an interval of \(10^{\circ}\). The irradiance half angle at the detector is \(20^{\circ}\). The logarithmic value of the BER is reduced when the transmitter half angle is around \(20^{\circ}\) and increases from \(-33.68\) to \(-22.12\) when the irradiance half angle at the source increases from \(10^{\circ}\) to \(50^{\circ}\). When the transmitter half angle is greater than or less than \(20^{\circ}\), a large BER is generated. Therefore, in addition to considering the influence of the transmitter half angle and the irradiance half angle at the source, the irradiance half angle at the detector also needs to be considered in order to reduce the BER. In Figure 3b, the irradiance half angle at the detector varies from \(0.001^{\circ}\) to \(80^{\circ}\), with an interval of \(2^{\circ}\), and that at the source varies from \(10^{\circ}\) to \(50^{\circ}\), with an interval of \(10^{\circ}\). When the irradiance half angle at the detector is \(0.001^{\circ}\), the logarithmic value of the BER increases from \(-17.59\) to \(-11.13\), with the irradiance half angle at the source increasing from \(10^{\circ}\) to \(50^{\circ}\). This indicates that the irradiance half angle at the source positively correlates with the BER. In Figure 3c, the communication distance varies from \(0.001\) to \(10\) m, with an interval of \(0.25\) m. The transmitter half angle varies from \(20^{\circ}\) to \(60^{\circ}\), with an interval of \(10^{\circ}\). When the distance is \(0.001\) m, the logarithmic value of the BER increases from \(-43.13\) to \(-25.85\), with the transmitter half angle increasing from \(20^{\circ}\) to \(60^{\circ}\). When the BER is at the FEC limit of \(3.8\times 10^{-3}\), the communication distance increases from \(2.44\) to \(3.97\) m with the  
Figure 3: Theoretical simulation results. The relationships between: (**a**) the irradiance half angle at the source and the transmitter half angle; (**b**) the irradiance half angle at the source and the irradiance half angle at the detector; (**c**) the transmitter half angle and communication distance; and (**d**) communication distance and detection surface area. transmitter half angle decreasing from 60\({}^{\circ}\) to 20\({}^{\circ}\). This indicates that the communication distance affects the communication quality of the communication system. In Figure 3d, the detection surface area varies from 0.001 to 20 cm\({}^{2}\), with an interval of 0.5 cm\({}^{2}\). The communication distance varies from 2 to 10 m, with an interval of 2 m. When the communication distance is 2 m, the logarithmic value of the BER reaches the minimum value of \(-\)37.1, and the detection surface area is 11 cm\({}^{2}\). When the detection surface area is larger than 11 cm\({}^{2}\), the logarithmic value of the BER does not decrease further. This indicates that when the communication distance is fixed, the continuous increase in the detection surface area has a limited impact on reducing the BER.