# Addressing the Potential of L5/E5a Signals for Road ITS Applications in GNSS-Harsh Environments +
## 3 Analysis
### Accuracy of the PVT solution  
The assessment of the PVT quality resides on measures of trueness (i.e., deviation from reference trajectory) and precision (i.e., repeatability). Table 2 summarizes the deviation (Root Mean Square, RMS) of the position solution for Xiaomi Mi 8 for the two sets of E1/L1/B1 and L5/E5a multi-constellation raw GNSS data.  
Figure 5: Multipath effect in meters (m) of L1/E1 and L5/E5a signals for Xiaomi Mi 8. The vertical dotted lines separate the intervals for each sub-trajectory, i.e., sub-urban (s), urban (u) and deep-urban (d). The different colors represent the GPS and Galileo satellites.  
Figure 6: Multipath effect in meters (m) of L1/E1/B1 and L5/E5a/B2a signals for One Plus Nord 2. 5G. The vertical dotted lines separate the intervals for each sub-trajectory, i.e., sub-urban (s), urban (u) and deep-urban (d). The different colors represent the GPS, Galileo and BeiDou satellites.  
Clearly, concerning Xiaomi Mi 8, Table 2 indicates a better performance for the L1/B1/E1 position solution (RMS: 2.9 m) compared to the L5/E5a (RMS: 3.5 m). Furthermore, a horizontal RMS value of 2.9, 5.3 and 6.6 m is achieved for the sub-urban, urban and deep-urban trajectories, respectively. These results indicate the superiority of the estimated solution when multi-constellation GNSS measurements are used.  
Two points are clearly evident concerning the L5/E5a solution no matter whether or not the accuracy obtained is significantly lower than that obtained for L1/E1/B1. Firstly, the Xiaomi MI 8 does not receive signals on B2a; therefore, more satellites are being monitored on the first frequency than on the second one. Secondly, this outcome is heavily affected by the poor observation geometry due to smartphone placement (dashboard).  
In contrast, opposite conclusions result for the horizontal position errors obtained for the OnePlus Nord 2 5G (Table 3). For the case of L5/E5a/B2a solutions, the horizontal RMS errors improve by 21%, 17.1%, 14.7% and 22.5% for the total, sub-urban, urban and deep-urban trajectories, respectively, with respect to the L1/E1/B1 solution. This improved performance is due to the superior precision of the GNSS measurements on L5/E5a/B2a bands when compared to the L1/E1/B1 counterparts. Furthermore, as already stated, the One Plus Nord 2 5G is capable of receiving an extra signal (i.e., B2a) compared to Xiaomi Mi 8, which allows for tracking more satellites on the second frequency. Finally, it is worth noting that the tuning process of OnePlus Nord 2 was not as straightforward as that for Xiaomi Mi 8, indicating that better or more advanced filter tuning could potentially lead to superior results for the OnePlus Nord 2 5G.  
In terms of horizontal velocity errors, both smartphones perform in a precision range of a few m/s (Tables 2 and 3). This performance could be attributed to the low precision of the Doppler-shift measurements acquired from _Android_ devices [14]. The Xiaomi Mi 8 performs best when L1/E1/B1 measurements are employed, resulting in an accuracy of 1.5 m/s over the whole experimental trajectory. Regarding OnePlus Nord 2, comparing the L5/E5a/B2a signal velocities to the L1/E1/B1 ones, an improvement of 19%, 20%, 16.7% and 5% is noted for the complete, sub-urban, urban and deep-urban trajectories.