## 4 Discussion  
The distance propagation model locates the node position according to wireless signal strength. The positioning method, based on ranging, determines the quantitative relationship between the signal strength and the node spacing, according to the model. The node spacing is the calculated distance between the base station coordinates and the vehicle coordinates. The fitting results of the model have a great impact on the accuracy of positioning. Based on the WFC fusion positioning scheme based on the optimal positioning result, the environmental impact indicator \(A\) and the path loss coefficient \(n\) in the model are taken as different values, and the positioning errors are respectively calculated for comparison. The original data of the same period are selected and calculated according to the positioning method in the WFC fusion positioning scheme. The environmental impact indicators are respectively selected (\(A=178.6135\), \(A=184.6135\), and \(A=180.6135\)) in the fitting result to obtain the effect of the positioning error, as shown in Figure 15.  
It can be seen from Figure 15 that compared with the positioning results of the fitted model, the positioning error of the calculation with different environmental impact indicators is significantly increased, indicating that the accuracy of the positioning effect cannot meet the requirements. Analyze the path loss indicator. Select \(n=7.892\), \(n=8.492\), and \(n=8.192\) in the fitting result, respectively, to obtain the effect diagram of the positioning error, as shown in Figure 16.  
It can be seen from Figure 16 that compared with the positioning results of the fitting model, the positioning error of calculating the position with different path loss coefficients is significantly increased, indicating that the accuracy of the positioning effect cannot meet the requirements. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Programme** & **WFA Algorithm** & **WFB Algorithm** & **WFC Algorithm** & **Accuracy Improvement** \\ \hline Mean value (m) & 43.32 & 48.56 & 39.97 & 7.74\%\(\dagger\) \\ RMSE (m) & 42.88 & 45.87 & 41.63 & 2.92\%\(\dagger\) \\ CRLB (m) & 11.25 & 1.65 & 13.03 & 15.82\%\(\dagger\) \\ GDOP & 1.29 & 2.62 & 0.99 & 23.26\%\(\dagger\) \\
67\% CDP (m) & 46.70 & 57.08 & 46.31 & 0.84\%\(\dagger\) \\
95\% CDP (m) & 123.69 & 127.55 & 122.53 & 0.94\%\(\dagger\) \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Positioning accuracy evaluation index. The changes in the environmental impact factor and the path loss coefficient have a negative impact on positioning accuracy, making the positioning error much higher than that of the WFC scheme. This indicates that the WFC fusion scheme is relatively better in the fusion positioning method based on ranging. Table 10 shows the comparison of positioning accuracy indicators when different parameters are selected for the model. It can be summarized from Table 10 that the selection of model parameters has a great influence on the error of the positioning results. A reasonable curve fitting can greatly reduce the error between the calculated distance and the true distance to obtain more accurate positioning results. The RMSE of the WFC fusion scheme, obtained according to the fitted distance propagation model, is 40.62 m, and the change of model parameters causes the positioning accuracy to decrease with varying degrees. The positioning effect of the four reference positioning schemes drops between 81.39% to 114.06%, and the average value of positioning error is above 100 m. According to the change of the selected model parameters, it can be explained that the change of the model parameters will have a negative impact on the positioning results and reduce the positioning accuracy of the vehicle. The positioning accuracy shows a downward trend with the change of the distance propagation model parameters, which is caused by the model parameters having reasonable calibration values, which makes the most accurate calculation.