## 5 Results
In Figure 10, we organize the results for a speed and different heights in the same plot. At a low speed, lower height flights (Figure 10a) present a higher variation in the small-scale fading. We speculate that this is related to the drone's inability to remain stable during flights at a low height when it receives strong gusts of wind. On the other hand (Figure 10b), there is no significant difference in the small-scale fading for flights at 3 km/h and different heights. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Environment** & **Path Loss Exponent** & **Speed (km / h)** & **Height (m)** \\ \hline Lake & \(-7.8\) & 1 & 8 \\ Lake & \(-8.9\) & 3 & 8 \\ Lake & \(2.9\) & 1 & 80 \\ Lake & \(2.0\) & 3 & 80 \\ Mixed region & \(3.7\) & 1 & 80 \\ Mixed region & \(3.8\) & 3 & 80 \\ Caatinga & \(3.7\) & 1 & 80 \\ Caatinga & \(1.9\) & 3 & 80 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Path loss exponent for different environments. \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Environment** & **Height (m)** & **Speed (km/h)** & **Average (\(\mu\))** & **Standard Deviation (\(\sigma\))** & **Window** \\ \hline Lake & \(8\) & 1 & \(-0.036457\) & \(4.9594\) & \(10\) \\ Lake & \(8\) & 3 & \(-0.00010684\) & \(5.1219\) & \(5\) \\ Lake & \(80\) & 1 & \(0.014171\) & \(1.5940\) & \(15\) \\ Lake & \(80\) & 3 & \(0.019407\) & \(1.3563\) & \(15\) \\ Mixed region & \(80\) & 1 & \(0.021741\) & \(1.8036\) & \(10\) \\ Mixed region & \(80\) & 3 & \(0.023567\) & \(1.4659\) & \(20\) \\ Caatinga & \(80\) & 1 & \(0.0089469\) & \(2.6579\) & \(10\) \\ Caatinga & \(80\) & 3 & \(-0.0052443\) & \(3.0010\) & \(15\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Shadowing parameters for different environments. Figure 11 presents CDFs for the Caatinga (Figure 10(a)) and Mixed regions (Figure 10(b)). Similar to the results of the Lake region at 80 m, there is no variation in small-scale fading at higher heights, regardless of the drone's speed. Small-scale fading samples were used to estimate the Doppler frequency. First, the theoretical LCR curves for the Weibull distribution were generated with Equation (6). Then, the LCR values were generated with the small-scale fading samples. Finally, the Equation (7) was used to estimate the Doppler. Figure 12 shows the results of the Doppler frequency estimation. The results for flights on the lake are shown in Figure 11(a). Doppler estimation is similar for almost all flights, except for the one at the height of 8 m and speed of 3 km/h. In this case, the drone was able to develop a more constant speed, since the lake has a natural barrier of vegetation on one of the edges that reduces the action of the wind. In this specific case, the aircraft was able to develop a higher flight speed compared to other measurements and, consequently, a higher Doppler frequency, as shown in Figure 11(a). Results for the Caatinga and Mixed regions \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Window**} & **Nakagami** & \multirow{2}{*}{**Rice (K)**} & **Rayleigh** & **Weibull** & **Height** & \multirow{2}{*}{**Environment**} & **Velocity** \\  & **(m, \(\Omega\))** & & **(\(\sigma\))** & **(\(\beta\), \(\lambda\))** & **(m)** & **(km/h)** \\ \hline
10 & 0.42621, 4.0043 & 0.00033815 & 1.415 & 1.1251, 1.4969 & 8 & Lake & 1 \\
5 & 0.54171, 1.8553 & 0.00032789 & 0.96315 & 1.3129, 1.1415 & 8 & Lake & 3 \\
15 & 0.4374, 2.6966 & 0.00027749 & 1.1612 & 1.1512, 1.2552 & 80 & Caatinga & 1 \\
15 & 0.43961, 2.6205 & 0.00027911 & 1.1447 & 1.1688, 1.2184 & 80 & Caatinga & 3 \\
10 & 0.44587, 2.4439 & 0.0002916 & 1.1054 & 1.1751, 1.1859 & 80 & Mixed region & 1 \\
20 & 0.37927, 3.2004 & 0.00020356 & 1.265 & 1.0619, 1.2123 & 80 & Mixed region & 3 \\
10 & 0.35111, 2.3994 & 0.00027483 & 1.0953 & 1.0072, 1.0094 & 80 & Lake & 1 \\
15 & 0.37418, 3.3069 & 0.00019419 & 1.2859 & 1.0548, 1.2181 & 80 & Lake & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Parameters of small-scale fading distributions for different environments. Figure 9: Estimated CDFs over the lake for the same height.