# Fast Deployment of a UWB-Based IPS for Emergency Response Operations
## 5 Performance Evaluation
### Static Tag Localization  
A set of 18 well-known positions (from now on called \(puntX\)) were defined to measure the performance of the UWB-based IPS when locating static objects. As can be observed in Figure 10, these positions aimed to represent the whole building, with eight of them placed on the ground floor and ten on the first floor. During the test, a tag was placed in each position on top of a tripod at a height of 1.80 m for less than 2 min. Table 4 compiles the rest of the configuration parameters of the proposed UWB-based IPS. As a first step of the static tag localization analysis, the SS-TWR procedure execution and the accuracy of the obtained rangings was evaluated. (A dataset with all the obtained rangings from this test is available at [[https://bitbucket.i2](https://bitbucket.i2) cat.net/users/toni_adame/repos/uwb-rangings]([https://bitbucket.i2](https://bitbucket.i2) cat.net/users/toni_adame/repos/uwb-rangings), accessed on 21 April 2023). As shown in Figure 11a, in 96 of the 108 considered tag-anchor pairs (i.e., 18 tag positions \(\times\) 6 anchors), the tag properly processes more than 90% of the expected rangings. In such cases, the few l  
Figure 10: Static localization maps. (**a**) Ground floor. (**b**) First floor. brief communication or processing issues. However, in some positions the tag experiences a permanent lack of UWB coverage from one or more anchors. This is particularly significant in _puntK_, where only three anchors are _visible_ more than 90% of time and the rest are usually _unreachable_. The mean absolute ranging error with respect to the actual tag-anchor distance is depicted in Figure 11b. The mean error is below 1 m in 80.56% of all considered tag-anchor pairs and achieves its maximum value (2.65 m) in the _puntM-anchor_#1a25 pair. At this point it is worth noting that the achieved performance is far from the optimum centimeter-level benchmark offered by UWB due to the strict NLOS character of the current testbed and the range overestimation introduced by the high distance between devices [77]. In particular, some of the greatest error values correspond to pairs with a low rate of received rangings, which confirms the instability of the wireless link in such cases. Another remarkable trend is that the error values greater than 1 m mainly belong to positions on the first floor of the building. The effect of the ground-floor ceiling, which acts as an additional obstacle hindering UWB signal propagation, is behind this behavior. The distance between the well-known position and the anchor does not constitute a major contributor to the ranging error, since the computed correlation coefficient between these two metrics accounts for 0.15 (here computed as the Pearson correlation coefficient, which is defined as \(\rho(A,B)=\frac{1}{N-1}\sum_{i=1}^{N}\left(\frac{A_{i}-\mu_{A}}{\sigma_{A}} \right)\left(\frac{B_{i}-\mu_{B}}{\sigma_{B}}\right)\), where \(\mu_{A}\) and \(\sigma_{A}\) are the mean and standard deviation of \(A\), respectively, and \(\mu_{B}\) and \(\sigma_{B}\) are the mean and standard deviation of \(B\), respectively). On the other hand, the dispersion of the computed rangings shown in Figure 11c does slightly correlate with the ranging error, with a computed coefficient of 0.42. In any case, the obtained rangings fed the multilateration algorithm, which estimated the tag position every \(T\sim 2\) s. Figure 10 shows the projection on the building map, per well-known point, of all obtained estimation samples and their average value. At first sight, the cloud of estimations is always located close to the actual tag position with a reduced number of outliers, with those mainly located on the first floor.