## 8 Numerical Results and Discussion
### Received Power in the VLC Scenario with IRS Position Optimization Based on an RNN  
The results in Figure 5, incorporating RNN-based IRS position optimization, show a significant improvement in the performance of VLC systems compared to the baseline results in Figure 4. The most important parameters of the RNN scheme are shown in Table 2. The optimal IRS positions, represented in coordinates by two mirrors in the corners for demonstration purposes, are located at (4.516, 1.519, 1.467) m for mirror (1, 1) and (4.882, 3.515, 1.541) m for mirror (10, 10) and have led to enhanced received power levels across all ADR configurations. For the pyramidal ADR with MRC, the maximum received power increased to 10.92 dB from 5.49 dB in the non-optimized case, and the minimum power improved to \(-9.11\) dB from \(-20.14\) dB, demonstrating the effectiveness of both IRS optimization and MRC.  
The hemispherical ADR with MRC also shows substantial gains, with a maximum power of 12.11 dB and a minimum of \(-8.94\) dB, compared to 6.37 dB and \(-19.59\) dB in the non-optimized scenario. These results highlight the robust performance of the hemispherical ADR in uniformly distributing power across the scenario when combined with RNN-optimized IRS positioning and MRC. However, the SBC technique, while improved, remains less effective than MRC. For the pyramidal ADR with SBC, the maximum power increased to 10.59 dB, and the minimum power improved to \(-18.11\) dB, compared to 0.81 dB and \(-23.40\) dB without the RNN.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Number of Inputs & \(N_{\text{PD}}\) (Number of photodiodes) \\ Number of Hidden Layers & 3 \\ Hidden State Size & 512 \\ Number of Outputs & \(3\times M\times N\) \\ Activation Function & ReLU \\ Optimizer & Adam \\ Learning Rate & 0.0005 \\ Number of Epochs & 80 \\ \hline \hline \end{tabular}
\end{table}
Table 2: RNN parameters.  
In particular, the hemispherical ADR with SBC achieved the highest maximum power of 11.94 dB, although its minimum power of \(-\)17.96 dB remains less favorable compared to MRC-based configurations. These findings emphasize the importance of RNN optimization in improving both peak and baseline performance. Furthermore, the performance gains underscore the synergy between advanced ADR designs and optimized IRS placement in addressing nonuniformities in power distribution in VLC systems.  
The SNR distribution shown in Figure 6 highlights the performance differences between various ADR configurations and signal processing mechanisms in a VLC scenario without IRS position optimization. The single-PD setup demonstrates the lowest overall SNR range, with a maximum of 69.27 dB and a minimum of 33.69 dB, reflecting significant performance degradation in areas farther from the LED source. In contrast, the use of ADRs significantly enhances the SNR distribution. For instance, the pyramidal ADR with MRC achieves a maximum SNR of 74.86 dB and a minimum of 54.28 dB, while the hemispherical ADR with MRC further improves these values to 76.00 dB and 54.87 dB, respectively. These results highlight the superiority of MRC in leveraging multi-element ADR designs to ensure a more consistent and high-quality signal across the scenario.  
Figure 5: Received powers in the indoor VLC scenario with IRS position optimization based on an RNN for different ADRs with signal selection or combination mechanisms.