# Fast Deployment of a UWB-Based IPS for Emergency Response Operations
## 5 Performance Evaluation
### Anchor Self-Location  
The anchor self-location tests were performed in order to study the precision and accuracy of the proposed GNSS-RTK-based solution. For this study, the GNSS antenna of the GNSS-RTK module was placed on top of each anchor, analyzing a total of six locations. A first analysis was performed on the dispersion of the position samples obtained during the localization phase. Figure 9 shows the temporal evolution of the received GNSS-RTK positions in each considered anchor location. For most of the locations, the system rapidly converged to a precise position. However, there were two anchors (namely, #8828 and #1A25) that presented a more disperse behavior. Next, Table 2 presents the quantitative study of the obtained position samples, including the degree of FIXED level achievement, the mean of the self-estimated horizontal accuracy error (\(\overline{hAcc}\)), which provides a level of positioning uncertainty, and the computed standard deviation for both X and Y coordinates (\(\sigma_{x}\) and \(\sigma_{y}\), respectively). Both the quality parameter value related to the solution of the GNSS carrier-phase ambiguity (DGNSS, FLOAT, or FIXED) and the \(hAcc\) value were directly extracted from the u-blox ZED-F9P module. More information can be found in its interface description [76]. The obtained values corroborate the graphical representation in Figure 9, where all the obtained position samples in each considered location converge to a stable point. In addition, the two anchors that showed a bigger dispersion also had slightly worse \(\overline{hAcc}\) values and some of their samples did not even reach the FIXED ambiguities. In this matter, the area where these anchors were placed did not have the best conditions, as the GNSS ground-based reference station sending the corrections was located further than recommended. Even so, this scenario has been considered convenient to analyze the performance of the system under realistic/non-ideal conditions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Anchor ID**} & **\% of Samples with** & \(\overline{hAcc}\) **(cm)** & \(\sigma_{x}\) **(cm)** & \(\sigma_{y}\) **(cm)** \\ \cline{2-5}  & **FIXED Ambiguities** & **\(\overline{hAcc}\) **(cm)** & \(\sigma_{x}\) **(cm)** & \(\sigma_{y}\) **(cm)** \\ \hline
**\#1A40** & 100 & 1.41 & 9.09 & 3.90 \\
**\#2 CDB** & 100 & 1.41 & 15.22 & 11.13 \\
**\#8828** & 100 & 1.43 & 19.78 & 28.43 \\
**\#5 BA0** & 100 & 1.41 & 8.10 & 6.59 \\
**\#3 EB** & 100 & 1.41 & 8.94 & 6.43 \\
**\#1A25** & 99 & 1.42 & 23.98 & 33.71 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: GNSS-RTK precision study. The evaluation of the positioning accuracy was conducted by analyzing the distance error between anchors. The study was carried out on the final position obtained once the self-location process was completed. Typically, the accuracy is calculated by comparing the computed position to the real one. However, since there was no alternative location method to determine the exact position of the anchors, the calculation was carried out indirectly with distances. In the presented testbed, the real distances between the anchors were calculated manually with different mechanisms: a tape measure and a laser meter. Although these measurement campaigns are not error-free, the resulting values can be effectively used as a benchmark and compared to those obtained from GNSS-RTK. The difference between both value sets, compiled in Table 3, can be considered as the GNSS-RTK error when computing distances between anchors and offers an idea of the resulting accuracy. Particularly, most of the errors remain below 30 cm and only a few surpass this threshold. Again, the anchors that show higher distance errors correspond to those that also presented worse precision (i.e., #8828 and #1A25). The time devoted to the deployment and activation of the IPS (\(T_{\text{IPS}}\)) may be critical in an ER operation.