## 10 Comparative Analysis of Propagation Models
### Comparison of Propagation Models on 6 GHz--SUI Model, PEM, ITU-R P.452-17  
For the 6 GHz frequency band, three models were examined: the Parabolic Equation Modeling (PEM) method used as a reference, the empirical SUI model, and the hybrid ITU-R P.452-17 model. The comparative error metrics are presented in Table 13.  
The results indicate that in the urban, mildly hilly environment, both the empirical SUI model and the hybrid ITU-R P.452-17 model produce significant errors. The SUI model systematically underestimates the field strength, whereas the hybrid model tends to overestimate it. The relative error is substantial in both cases, thus reinforcing the earlier conclusion that neither model provides adequate accuracy in this type of environment. \begin{table}
\begin{tabular}{l l l l l l l l} \hline \hline  & \multicolumn{6}{c}{**6 GHz**} \\ \hline \multirow{2}{*}{**Base Station**} & \multirow{2}{*}{**Model**} & \multirow{2}{*}{**Type**} & \multirow{2}{*}{\(n\)} & \multicolumn{2}{c}{**RMSE**} & \multirow{2}{*}{**MAE**} & \multirow{2}{*}{**Bias**} & \multirow{2}{*}{**RelErr**} \\  & & & & **(dB\({}_{\text{B}}\)V/m)** & & & **(dB\({}_{\text{B}}\)V/m)** & **(dB\({}_{\text{B}}\)V/m)** & **(\%)** \\ \hline \multirow{2}{*}{TestBS\_1} & \multirow{2}{*}{SUI} & Test points & 30 & 38.56 & 32.05 & \(-\)4.45 & 97.49 \\  & & Line-based & 12,766 & 46.38 & 39.78 & \(-\)18.49 & 123.65 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 31.68 & 23.28 & 13.06 & 100.18 \\  & & Line-based & 12,766 & 35.09 & 22.69 & 8.32 & 229.57 \\ \hline \multirow{2}{*}{TestBS\_2} & \multirow{2}{*}{SUI} & Test points & 30 & 54.67 & 54.23 & \(-\)54.23 & 82.53 \\  & & Line-based & 11,047 & 52.73 & 50.67 & \(-\)50.44 & 65.03 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 6.83 & 5.69 & \(-\)2.26 & 8.64 \\ \cline{2-7}  & & Line-based & 11,047 & 10.63 & 7.58 & \(-\)5.63 & 9.17 \\ \hline \multirow{2}{*}{TestBS\_3} & \multirow{2}{*}{SUI} & Test points & 30 & 47.52 & 40.43 & \(-\)26.83 & 107.58 \\  & & Line-based & 11,065 & 52.10 & 44.38 & \(-\)14.94 & 217.74 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 25.49 & 14.98 & 3.04 & 72.51 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 47.52 & 31.64 & 8.71 & 302.69 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 25.49 & 14.98 & 3.04 & 72.51 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 54.67 & 54.23 & 54.23 & 82.53 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 6.83 & 5.69 & \(-\)2.26 & 8.64 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 6.83 & 5.69 & \(-\)2.26 & 8.64 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 47.52 & 40.43 & \(-\)26.83 & 107.58 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 11,065 & 52.10 & 44.38 & \(-\)14.94 & 217.74 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 30 & 25.49 & 14.98 & 3.04 & 72.51 \\ \cline{2-7}  & ITU-R P.452-17 & \multirow{2}{*}{ITU-R P.452-17} & Test points & 11,065 & 44.27 & 31.64 & 8.71 & 302.69 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Error metrics of models SUI and ITU-R P.452-17 relative to the PEM model at 6 GHz, based on both test point and path-based simulations. In the flat, lowland area, the ITU-R P.452-17 model maintains the level of accuracy observed at 3.6 GHz compared to the PEM, making it a cost-effective alternative to the deterministic model in this setting as well. In contrast, the SUI model drastically underestimates the field strength, rendering it unsuitable--even in this simple form--for reliable field strength prediction over flat terrain.