## 4 Results
### Experimental Characterization of LoRa Coverage  
This section presents the experimental results of the LoRa network coverage characterization in an urban environment. A mobile LoRa transmitter sends one LoRa packet per  
Figure 5: Statistical analysis of the real-world building-based O-FDTD simulated Received Signal Strength Indicator (RSSI). (**a**) 2D histogram of combined RSSI and distance occurrences in the simulated RSSI map. The color scale indicates the relative occurrence rate, normalized to the number of map pixels. The dashed white lines represent the free-space RSSI (\(P_{\text{FS}}\)) for transmitter gains \(\text{G}_{\text{TX}}\) of 0 and +20 dBm, and the receiver sensitivity \(\text{P}_{\text{Rx}}\) of \(-124\) dBm, as indicated by the labels. The vertical dotted line indicates the 300 m spatial observation window used in the simulated RSSI map. (**b**) Free-space RSSI, \(\text{P}_{\text{FS}}(\text{G}_{\text{TX}}=+20\) dBm) in comparison to the mean O-FDTD simulated RSSI over distance (blue). The green and red highlights indicate the distances for which the simulated RSSI is, on average, above and below the receiver sensitivity.  
Figure 6: Distance dynamics of O-FDTD simulated Received Signal Strength Indicator (RSSI) for a sample of regions within the simulated cityscape maps. (**a**) Map of the arbitrarily selected propagation directions, with \(\Delta\theta=5^{\circ}\) and \(\theta=-135^{\circ}\), \(-45^{\circ}\), \(45^{\circ}\) and \(135^{\circ}\). The vivid and faded-colored regions indicate the analyzed and disregarded areas. (**b**) Mean RSSI over distance for each of the selected propagation directions.  
second containing multiple sensor measurements. The connection is tested by displacing the emitter and monitoring the timestamps of packet arrivals at the gateway as a function of the transceiver GPS position. We found that the time gap between packet arrivals changes directly from the set value of 1 s (connection established) and infinity (connection broken). Using this system, we determined the signal loss locations in every radial direction around the receiver by moving the transmitter around the gateway. Figure 7a shows a color-coded plot of the time gap between packet arrivals measured over the performed trajectory. The receiver is located at the center of the map. Using an iterative interpolation (flood-fill-like) script, we expanded the trajectory information (line) into a spread coverage area (2D color-coded map), as shown in Figure 7b.  
The iterative progress of the integration algorithm is shown in Figure 8 for 0 (starting point), 20, 40, and 80 iterations. The resulting map shows two regions of time gap between packet arrivals equal to 1 s (network-covered areas) and \"infinity\" (here limited at 40 s, non-covered areas). The map shown in Figure 7b corresponds to the final result overlaid onto the city map. We defined the experimental coverage region, i.e., the region where the connection is established, as the locations for which the interpolated time gap between packet arrivals is lower than 20 s, whose edge is indicated by the dashed line in the final map of Figure 8.  
In the following Section 4.4, the simulated and experimental coverage regions are overlaid and compared.