## 4 Results and Discussions
### Channel Impulse Response
\begin{table}
\begin{tabular}{l l l} \hline \hline
**UM Simulation Scenario** & **Values** & **References** \\ \hline \multicolumn{3}{l}{**Tunnel Parameters**} \\ \hline Dimensions (\(w\times l\times h\)) & (\(3\times 6\times 5\)) m & \\ Coordinates of the \(LED\)\((x,y,z)\) & (\(0.5\times 3\times 4.5\)) m & \\ Coordinates of the \(PD\)\((x,y,z)\) & (\(1\times 3\times 1.8\)) m & \\ \hline \multicolumn{3}{l}{**Channel parameters**} \\ \hline Absorption coefficient, (\(Q_{\text{abs}}\)) & 1.3 & [23] \\ Atmospheric parameter, \(\gamma\) & 0.017 & [12] \\ Atmospheric parameter, \(g\) & 0.72 & [12] \\ Atmospheric parameter, \(f\) & 0.5 & [12] \\ AWGN power spectral density (\(\text{A}/\text{Hz}\)) & \(2.5\times 10^{-23}\) & [28] \\ LED rotation angle, \(\alpha_{i}\)\((^{\circ})\) & 45 & [26] \\ LED tilt angle, \(\beta_{i}\)\((^{\circ})\) & 45 & [26] \\ Noise bandwidth (MHz) & 100 & [29] \\ PD rotation angle, \(\alpha_{i}\)\((^{\circ})\) & 45 & [26] \\ PD tilt angle, \(\beta_{i}\)\((^{\circ})\) & 45 & [26] \\ Scatterer reflection coefficient, \(\rho_{s}\) & 0.1 & [23] \\ Scattering coefficient, (\(Q_{\text{sca}}\)) & 0.4 & [23] \\ Sphere radius, \(R\) (m) & 1 & [16,20] \\ Wall reflection coefficient, \(\rho_{w}\) & 0.6 & [26] \\ Wall rotation angle, \(\alpha_{w}\)\((^{\circ})\) & \(U\!I\![0,\!180]\) & [26] \\ Wall tilt angle, \(\beta_{w}\)\((^{\circ})\) & \(U\!I\![0,\!180]\) & [26] \\ \hline \multicolumn{3}{l}{**VLC transceiver parameters**} \\ \hline Average transmitted power, \(P_{l}\) (W) & 5 & [23] \\ Band-pass filter of transmission & 1 & [6] \\ Dust concentration \(C\) (mg/m\({}^{3}\)) & 15 & [18,19] \\ Dust particle radius, \(r_{d}\) (\(\upmu\)m) & \(U\!I\![0.2,\!2]\) & [18,19] \\ FoV, \(\Theta\)\((^{\circ})\) & 70 & [23] \\ Gain of the optical filter & 1 & [23] \\ Lambertian mode number, \(m\) & 1 & [16,20] \\ LED wavelength, \(\lambda\) (nm) & 580 & [23] \\ Modulation type & OOK & [9] \\ Modulation bandwidth (MHz) & 50 & [9] \\ Modulation index & 0.3 & [9] \\ Optical filter bandwidth (nm) & 340 to 694.3 & [23] \\ Optical filter center wavelength (nm) & 580 \(\pm\) 2 & [23] \\ Optical filter full width half max (nm) & 10 \(\pm\) 2 & [23] \\ Physical active area, \(A_{p}\) (cm\({}^{2}\)) & 1 & [6] \\ Reflective element area, \(\Delta A_{w}\) (cm\({}^{2}\)) & 1 & [12] \\ Refractive index, \(m_{s}\) & 1.5 & [6] \\ Responsivity, \(R_{PD}\) (A/W) & 0.53 & [6] \\ Semi-angle at half power, \(\phi_{1/2}\)\((^{\circ})\) & 60 & [23] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: UM-VLC system simulation parameters. The specific approach and analysis of the scattering component based on the variation of \(N\) values are presented in Figure 4. Here, \(N\) was varied between values of 20 and 200 dust particles in order to observe their behavior and differences in the CIR curves. It is possible to notice that for all the values of \(N\) chosen, the temporal behavior of the CIR curves is the same. Therefore, we can denote that the hemispherical distribution has the same behavior regardless of the value of \(N\). However, and confirming the finding in Figure 3, we can observe that for values of \(N\) greater than 120, the CIR curves have similar magnitudes, which vary between them by a factor of \(0.2\times 10^{-9}\). For a better comparative interpretation of the CIRs curves shown in Figure 4, we can verify the maximum magnitude values of the CIRs by varying \(N\) in Table 2.  
Figure 3: UM-VLC CIR curves for **(a)** 40 and 60 dust particles in the hemispheric area, and UM-VLC reference scenario, Reprinted from ref. [12], and **(b)** 100, 150, and 200 dust particles in the hemispheric area.