# LoRa Technology Propagation Models for IoT Network Planning in the Amazon Regions
## 5 Results
### Analysis of RSSI and SNR Variation and Rate of Received Packets by SF  
The en-route propagation analysis addresses the non-line-of-sight (NLOS) conditions arising from obstructions like trees and buildings between the transmitter (Tx) and receiver (Rx) antennas. These obstructions impact radio link propagation performance, and the spreading factor (SF) value also plays a crucial role through airtime and signal sensitivity. It is essential to analyze how the NLOS condition affects packet efficiency based on the spreading factor type and the variation in RSSI and SNR values measured along the route. The box plot in Figure 9 illustrates the variation of RSSI values collected in SF7, SF8, and SF9. Across the route, values range from \(-60\) to \(-110\) dBm, with a maximum of \(-60\) dBm for SF8 and \(-110\) dBm for SF7 and SF8. It is noteworthy that sensitivity and SF type are directly proportional, meaning lower SF values result in lower signal sensitivity. However, lower SF values also lead to shorter airtime. The RSSI data range for SF7, SF8, and SF9 is from \(-64\) to \(-110\) dBm, \(-60\) to \(-110\) dBm, and \(-65\) to \(-115\) dBm, respectively. The average RSSI value for SF7, SF8, and SF9 was \(-84.62\) dBm, \(-85.85\) dBm, and \(-87.76\) dBm, respectively. Figure 9: Box plot of the distribution of RSSI data measured, with \(-86\) dBm, \(-86\) dBm, and \(-88.5\) dBm for the median (in red) of the data in SF7, SF8, and SF9. The box plot in Figure 10 displays the variation of SNR values collected in SF7, SF8, and SF9. The signal-to-noise ratio (SNR) measures the strength of a signal to background noise. The noise floor usually sets the limit for detecting a signal; however, LoRa technology can operate below the noise floor and decode signals at SNR values as low dB\(-\)20 dB [50]. SNR values in LoRa typically range between \(-\)20 and 10 dB. A value close to 10 dB indicates a stronger received signal and less noise. In our results, SNR data range from 10.8 to \(-\)1.8 dB, 12.5 to \(-\)5.5 dB, and 13.8 to \(-\)9 dB for SF7, SF8, and SF9, respectively. The average SNR value was 7.54, 8.71, and 8.76 dB for SF7, SF8 and SP9, respectively. RSSI and SNR values are key indicators of the capabilities of an LoRa radio receiver's capabilities. RSSI measures the signal level, while SNR determines the quality of the received signal, indicating how close it is to failure or noise [25]. Table 3 displays the dispersion grade values, represented by the standard deviation (\(\sigma\)) in dB for RSSI and SNR for SF7, SF8, and SF9. In analyzing the rate of received packets, it is important to note that some data collected at the gateway may lack RSSI and SNR information. To address this, we implemented a counter at the gateway that tracks the amount of data with and without RSSI and SNR information. This allows us to determine the rate of received packets by calculating the percentage of data containing RSSI and SNR information compared to the total amount of data sent and collected. For analyzing the percentage of packets received, we use the ratio between the total number of packets sent (\(PS\)) and the total number of packets received (\(PR\)) to calculate the rate of received packets (\(RRP\)):  
\[RRP(\%)=PR/PS \tag{10}\]  
The rate of received packets (RRP) depends on the signal level and quality (noise level). RRP values are 75.78%, 86.29%, and 92% for SF7, SF8 and SF9, respectively. These values are supported by the highest SNR values for SF9, SF8, and SF7, respectively. Average RSSI and SNR values further validate RRP, emphasizing the SF9 data with the highest RRP \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **SF7** & **SF8** & **SF9** \\ \hline RSSI & 10.06 & 10.34 & 10.88 \\ \hline SNR & 2.81 & 3.21 & 4.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The values of the standard deviation (\(\sigma\)) of the RSSI and SNR values for SF7, SF8, and SF9. Figure 10: Box plot of the distribution of SNR data measured, with 8.8 dB, 10 dB, and 10 dB for the median (in red) of the data in SF7, SF8, and SF9.