## 3 Materials and Methods
### Location Algorithm Verification
#### 3.3.1 Accuracy Analysis of Fusion Algorithm
Analysis of WFC Fusion Positioning Accuracy  
The WFC fusion positioning is a positioning scheme based on range-based trilateral measurement positioning, least-squares positioning, and non-range-based centroid positioning fusion. Figure 10 shows the comparison between the WFC fusion scheme vehicle positioning trajectory and the vehicle driving trajectory. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Programme** & **Centroiding** & **WFB Fusion Location Algorithm** \\ \hline Mean value (m) & 189.65 & 48.56 \\ RMSE (m) & 89.10 & 45.87 \\ CRLB (m) & - & 1.65 \\ GDOP & 1.91 & 2.62 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Positioning accuracy evaluation index. Figure 9: WFB cumulative distribution probability. It can be seen from Figure 10 that the positioning trajectory presents a similar result to that of WFA, and the overall positioning accuracy is suitable. According to the positioning result calculated by Formula (22), the positioning accuracy analysis diagram of the WFC fusion method is obtained, as shown in Figure 11.  
In Figure 11, the accuracy analysis of the average positioning error, the RMSE, and the CRLB lower limit of the WFC fusion positioning scheme is carried out. Comparing the WFC scheme with the least-squares positioning result with relatively good positioning results, the WFC fusion algorithm is better than the least-squares method. Compared with least-squares positioning, the positioning precision of the WFC scheme is significantly improved, and the distance of the coordinate error with a large error is obviously converged. Compared to the RMSE of the two methods, the RMSE of the WFC scheme is slightly lower than the least-squares positioning result. The WFC fusion has better positioning accuracy than least-squares positioning. Secondly, the positioning error of WFC fusion positioning is closest to CRLB, which shows that the positioning accuracy of the WFC fusion scheme is relatively better. The quantitative comparison of positioning accuracy is shown in Table 8.  
Figure 11: WFC fusion method analysis of the positioning accuracy. Figure 10: WFC fusion method trajectory. Through the accuracy evaluation indicators in Table 8, the positioning accuracy of the four positioning schemes is evaluated and compared from the four aspects of error distance, RMSE, CRLB, and GDOP. The result is that the WFC fusion algorithm is better than the least-squares method, the trilateral positioning algorithm, and centroid positioning. In terms of the average error value, the average error of WFC fusion positioning is 39.97 m. By comparing this value to the 88.40 m for trilateral positioning, 2.91 m for least-squares positioning, and 189.65 m for centroid positioning, the average positioning error is reduced by 54.79%, 45.18%, and 78.92%, showing that the positioning effect is significantly improved. In terms of the RMSE, the RMSE of the WFC scheme is 41.63 m compared to the 53.88 m for trilateral positioning, 43.45 m for least-squares positioning, and 89.10 m for centroid positioning, where the average positioning error is reduced by 22.74%, 4.19%, and 53.28%. In terms of the GDOP, the GDOP of the WFC fusion scheme is 0.99, which is better than the 1.18 of trilateral positioning, the 1.27 of least-squares, and the 1.91 of the centroid algorithm. Figure 12 is the CDP function diagram of the WFC fusion positioning scheme. It can be seen from the figure that the positioning error of the WFC fusion scheme is relatively concentrated in the range of 0-40 m. From the CDP, 67% of the positioning accuracy is within 46.31 m, and 95% of the positioning accuracy is within 122.53 m.  
In summary, the WFC fusion scheme has the most significant improvement effect on positioning accuracy. From the mean error, RMSE, CRLB, and GDOP, the positioning accuracy of the fusion algorithm is much higher than the positioning results of the centroid algorithm, the trilateral measurement positioning, and the least-squares.