## 4 Experimental Validation and Analysis
### Discussion and Analysis
#### 4.2.3 EMC Analysis  
This section investigates the correlation between the BER of the vehicular voice communication systems and their evaluation scores, and further examines the inherent relationship between these parameters and overall EMC. The results (Table 8 and Figure 12) show the following:  
1. All experimental schemes  
A comparative performance analysis was conducted across all schemes. The results consistently demonstrate a correlation between the evaluation score and BER. The main trends are as follows: The EMC of the system in Scheme 3 is superior to that of other schemes, while Scheme 5 consistently exhibits the poorest EMC performance.
2. Same-Position, Same-Vehicle control experiment group (V1-PA-1 vs. V1-PA-2)  
A comparative performance analysis was conducted between Schemes 1 and 2. Scheme 1 achieved an evaluation score of 0.258 with a measured BER of \(8.25\times 10^{-4}\), while Scheme 2 obtained an evaluation score of 0.582 with a measured BER of \(7.73\times 10^{-5}\). Comprehensive analysis indicates that Scheme 2 exhibits superior EMC performance.
3. Different-Position, Same-Vehicle control experiment group (V2-PC vs. V2-PB)  
A comparative performance analysis was conducted between Schemes 4 and 5. Scheme 4 achieved an evaluation score of 0.193 with a measured BER of \(8.83\times 10^{-4}\), while Scheme 5 obtained an evaluation score of 0.049 with a measured BER of \(9.21\times 10^{-4}\). Comprehensive analysis indicates that Scheme 4 exhibits superior EMC performance.
4. Same-Position, Different-Vehicle control experiment group (V1-PC vs. V2-PC)  
A comparative performance analysis was conducted between Schemes 3 and 4. Scheme 3 achieved an evaluation score of 0.60 with a measured BER of \(6.47\times 10^{-5}\), while Scheme 4 obtained an evaluation score of 0.193 with a measured BER of \(8.83\times 10^{-4}\). Comprehensive analysis indicates that Scheme 3 exhibits superior EMC performance.  
Figure 11: Simulated and measured BERs and SNRs.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Comparative Experiment** & **V1-PA-1** & **V1-PA-2** & **V1-PC** & **V2-PC** & **V2-PB** \\ \hline BER & \(8.25\times 10^{-4}\) & \(7.73\times 10^{-5}\) & \(6.47\times 10^{-5}\) & \(8.83\times 10^{-4}\) & \(9.21\times 10^{-4}\) \\ SNR (dB) & 5.36 & 6.13 & 6.51 & 5.88 & 4.94 \\ \hline \hline \end{tabular}
\end{table}
Table 8: BER measurement values.  
(5) Different-Position, Different-Vehicle control experiment group (V1-PC vs. V2-PB and V1-PA-1 vs. V2-PC)  
A comparative performance analysis was conducted between Schemes 3 and 5. Scheme 3 achieved an evaluation score of 0.60 with a measured BER of \(6.47\times 10^{-5}\), while Scheme 5 obtained an evaluation score of 0.049 with a measured BER of \(9.21\times 10^{-4}\). Comprehensive analysis indicates that Scheme 3 exhibits superior EMC performance.  
A comparative performance analysis was conducted between Schemes 1 and 4. Scheme 1 achieved an evaluation score of 0.258 with a measured BER of \(8.25\times 10^{-4}\), while Scheme 4 achieved an evaluation score of 0.193 with a measured BER of \(8.83\times 10^{-4}\). Comprehensive analysis indicates that Scheme 1 exhibits superior EMC performance.