# UAV-BS Site Planning Based on Circular Coverage Strategy
## 5 Experimental Results  
The above methods are simulated, and the key parameters used in the simulation system are shown in Table 3. The flight control center contains 50 rotary-wing UAVs equipped with wireless communication base stations for arbitrary use, and the target area is a circular scene with a radius of \(R=1000\) m. The UAV's flight altitude is \(H=100\) m, with a maximum transmission power of \(P_{\max}=5\) W for each UAV-BS. The channel attenuation exponent is \(\alpha=4\), the channel noise is \(P_{\rm noise}=-174\) dBm\(/\)Hz, and the receiving SNR threshold is \(\gamma_{th}=5\) dB. In the above scenario, using the CCPO strategy, at least 20 UAVs need to be deployed to ensure full coverage of the target area. The corresponding site planning is shown in Figure 3. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Target area radius \(R\) & 1000 m \\ UAV-BS deployment height \(H\) & 100 m \\ Number of UAVs in control center \(N\) & 50 \\ Noise spectral density \(\eta_{0}\) & \(-174\) dBm\(/\)Hz \\ A2G channel attenuation exponent \(\alpha_{1}\) & 2 \\ Maximum transmission power of single & 5 W \\ UAV-BS \(P_{\max}\) & 5 dB \\ Reception SNR threshold \(\gamma_{th}\) & 5 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation parameter value. Figure 4 illustrates the impact of UAV flight altitude \(H\) on system power consumption, with all other parameters held constant. The horizontal line segment indicates that under the condition of limited transmission power of UAV-BS, the corresponding deployment scheme cannot meet the full coverage requirement of the target area and will be discarded when selecting the optimal deployment scheme. After the horizontal line, it can be seen that the total transmit power function of the system is convex, which is consistent with Equation (21) and the results obtained by P4. Obviously, as the UAV flight altitude increases, the minimum number of UAV-BS required to achieve full coverage increases, and the total transmission power of the system increases, but the number of UAVs required for the optimal deployment decreases. This is because as the flight altitude increases, the distance between UAV-BS and ground users increases, and the transmission power required to achieve coverage also increases accordingly. Figure 5 illustrates the impact of the attenuation exponent \(\alpha\) on the site planning results under the condition that all other parameters are the same. As shown in the figure, as the attenuation exponent increases, the number of UAVs required to meet full coverage requirements using the CCPO strategy also increases. According to Equation (12), an increased attenuation exponent means that more transmission power is needed to provide communication services to ground users at the same distance. Additionally, the minimum point of the system power curve shifts to the right, increasing the optimal number of UAV-BSs. In scenarios where signal degradation is severe, we ensure that the system can still achieve full coverage by increasing both the transmission power and the number of UAV-BSs deployed. This approach is necessary to compensate for the power loss due to channel attenuation, especially in special scenarios where the attenuation exponent \(\alpha\) significantly impacts the site planning results. By appropriately increasing the transmission power of the UAV-BSs, we can effectively counteract the increased attenuation and maintain the desired level of service coverage. Figure 3: UAV-BS site planning diagram when the radius of the target area is 1000 m.  
Under the condition that all other parameters are the same, this paper discusses the impact of the target area size and SNR threshold on site planning. As shown in Figure 6, with the same target area radius, \(\gamma_{th}\) takes 0 dB, 2.5 dB, and 5 dB respectively. Figure 6b is a magnification of a part of Figure 6a. As the SNR threshold increases, the optimal number of UAV-BSs deployed using the circular coverage method increases significantly.