# A LoRaWAN Architecture for Communications in Areas without Coverage: Design and Pilot Trials
## 5 Results
### Experimental Coverage Analysis  
Experimental analysis for coverage testing was performed in three types of real-world environments--urban, rural and natural--for testing the system in different situations. After several practical experiments in each environment, RSSI and SNR data were collected to estimate the reception quality. Figure 11 shows the RSSI values as a function of the distance from the end device to the central node. The black line represents the RSSI set with the free space propagation model calculated for the measurement distances [44; 46]. The red line represents the mean RSSI values taken for given distances in the urban environment. The blue line represents the mean RSSI values in the rural environment, and the green line shows the experimental measurements in the natural environment. Using the free space model, our experimental results were compared with the theoretical ones in each of the case studies. As expected, the experimental results followed the trend of the ideal model, although they presented clearly worse values. In short, the RSSI decreased as a function of the distance to the central node. In addition, the RSSI was also affected by other effects such as large- and small-scale fading [25]. Large-scale fading is mainly caused by reflection, refraction and scattering against large obstacles. Small-scale fading is produced by multipathing or due to doppler effects. These effects can considerably decimate the signal. The three types of environments show that the system behaved similarly. This highlights that the urban measurement environment was not the most suitable because the bidirectionality capability was lost early (around 600 m). Moreover, as shown in the study [26], our results were relatively low. It is worth noting that the rural and natural environments presented similar behaviors, but the natural environment was slightly better due to the fact that the obstacles that appeared in the rural area interfered with the signal. This result was positive, because our main focus in this work was on natural areas. In turn, the rural environment presented a lower RSSI than those measured in the urban environment. These results are due to the fact that the measurements taken in the urban environment were made with a line of sight until finding buildings. This may also affect that the measurements in the rural environment presented buildings close to our central node, and at the time of measurement, the weather conditions were not favorable (e.g., fog and rain). Similarly, the averaging of the values obtained in terms of the SNR is shown in Figure 12, which establishes a direct relationship between the transmitted signal and the noise introduced as a function of the distance to the central node and the differences between the environments. The natural and urban environment offered the best performance in terms of the SNR, and the rural environment stood out for its low SNR. In this case, most of the SNR measurements taken were negative due to the chosen area and climate conditions. This proves that the system is robust to noise and fading that might appear in  
Figure 11: Comparison of theoretical and experimental RSSIs as a function of distance. emergencies, as the TeamUp system was able to maintain the connection bidirectionally even when the signal was below the noise floor. These previous analyses provided us with information on the signal strength or its relationship with the noise usually introduced by the transmission channel. Therefore, it was decided to make a statistical study of the measurements obtained as a function of the three environments (urban, rural and natural). Figures 13 and 14 show the experimental cumulative distribution function (ECDF) and upper and lower confidence bounds (UCB and LCB, respectively) of the RSSI and SNR measurements as a function of the test areas.