# LPWAN-Based Vehicular Monitoring Platform with a Generic IP Network Interface
## 6 Results  
A clear view of good operation of our platform can be seen in the data collected from the vehicle, both in real time and in a historical fashion. Figure 8 includes a screen-shot of the Grafana platform hosted by the data server. An OpenStreetMap component has been used to highlight the path followed by our Honda Civic within the campus. A different color is used to indicate the stretches where the car drove at higher speeds (consider that the campus has a speed limit of 20 km/h). The screen-shot in Figure 9 shows a more general view of the capabilities of the monitoring application. Here, apart from the path followed by the car, the raw parameters received and both real-time and historical records of the OBD data are shown. In the plot on the right, the engine load, revolutions per minute, and speed are shown. An interesting issue, detected when gathering the vehicle speed, was the difference between OBD and GPS data. Figure 10 shows the speed reported in one of the tests. It can be seen that GPS speed \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Transmission power & 14 dBm \\ Spreading Factor (SF) & 12 \\ Coding Rate (CR) & 4/5 \\ Bandwidth (BW) & 125 kHz \\ Bit-rate & 239 bps \\ Packet length & 14 Bytes \\ Packet rate & 0.33 packets per second \\ Adaptive Data Rate (ADR) & No \\ Retransmissions & No \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Transmission parameters. values are delayed, as compared with the OBD data. This is attributed to two factors: The positioning algorithm, which uses cumulative data to compute fixes, and the buffering carried out by the GPS UNIX daemon used (_gpsd_), which saves the last computed position to serve requests from the OBU data gathering application. In order to validate our proposal in a real scenario from a communications perspective, a performance evaluation of LoRaWAN was also conducted around the university campus, obtaining the results shown in Figure 11. Concretely, the LoRaWAN-enabled OBU periodically transmitted data packets to the gateway with the aim of finding non-covered zones. The RSSI, measured by the gateway in dBm, is plotted on the campus map, indicating good operation of the system around the ring. It can  
Figure 8: Visualization of the path followed by the vehicle in the Grafana dashboard. Figure 9: Main view of the Grafana dashboard. be seen that lower RSSI values are obtained in the lower right corner, which represents a location at 1.4 km away from the gateway. The effect of buildings is noticeable, observing the greatest RSSI values, which are not obtained at the nearest area. This is due to a group of buildings, south-east of the gateway location. In fact, as expected, the best coverage is obtained when a direct line of sight is obtained through the buildings (blue spots). Overall, observe that the lowest RSSI level attained was \(-101\) dBm, far from the gateway receiving sensitivity; around \(-140\) dBm. Although it can be seen in Figure 11 that the performance level of the system is high, in terms of channel reliability (no shadow zones), the Packet Delivery Ratio (PDR) was also studied in this scenario. Thereby, with the selected LoRa configuration (SF = 12, CR = 4/5, and BW = 125 kHz), we obtained a PDR of 95%. This is an acceptable figure, which permits continuous vehicle monitoring with trustworthiness and stability. Regarding the focus of this validation study, with this deployment the institutional service vehicles can be perfectly tracked, all around the university campus. In addition, one should consider that these vehicles are usually electrically-powered; hence, they present important energetic restrictions. With the use of this LPWAN-based solution, the battery energy can be greatly saved by substituting our laptop with an embedded computer platform. After the whole evaluation, we have checked the operation of the system and its potential to monitor vehicles using our generic LPWAN communication system.