# UAV-BS Site Planning Based on Circular Coverage Strategy
## 5 Experimental Results
This is because as SNR increases, the area covered by a fixed power decreases, and thus the number of UAV-BSs required to achieve full coverage also increases. Additionally, under the same SNR threshold, the number of UAV-BSs required by the optimal site planning solution overall shows a trend of increasing first, then remaining constant, and then decreasing as the target area radius increases, with local step-like growth. As can be seen in Figure 6a, when the SNR threshold is 5 dB, the optimal number of UAV-BSs increases with the target area radius within the range of 1000 m to 1800 m, remains constant between 1800 m and 2200 m, and then decreases. This trend occurs because, with the CCPO site planning proposed in this paper, the coverage radius of the UAV-BS increases with the target area radius, and the transmission power of a single UAV-BS also increases. However, the power of the UAV-BS is limited, and the coverage radius is constrained. The  
Figure 4: UAV-BS site planning diagram when the radius of the target area is 1000 m.  
Figure 5: The influence of attenuation index on the transmitted power of the system. balance between these two is achieved by increasing the number of UAV-BSs to meet the full coverage requirement. The platform section appears because the maximum number of UAV-BSs is affected by the ACC capacity. Comparatively, deploying 50 UAVs results in the minimum system power consumption; as the target area radius continues to increase, the transmission power of the UAV-BSs deployed using circular coverage power optimization will exceed the maximum transmission power. With 50 UAVs, it is impossible to achieve full coverage of the target area under the maximum transmission power constraint. At this point, it is necessary to increase the number of UAV-BSs that the control center can accommodate or raise the transmission power limit to solve this problem, indicating that the size of the target area has guiding significance for the control center capacity planning. Figure 6b describes the impact of minor variations in the target area radius on the UAV-BS site planning solution. When \(R\) takes values between 1120 m and 1136 m, the number of UAVs required is consistently 24, with a total system power consumption of 444.37 W. This is because the CCPO strategy adopted in this paper is a geometric coverage strategy, where minor increases in the target radius have a negligible impact on the coverage range of the UAV-BSs, and the optimal number of UAV-BS deployments does not change significantly. This result meets the requirements for the CCPO problem's decentralized solution, and also indicates that the CCPO strategy does not require a new site plan when the target area is slightly adjusted. In practical applications, this feature can effectively reduce the investment in labor and computational resources. Under the condition that the target area radius ranges from 1000 to 2000 m, and with other parameters as shown in Table 3, this paper compares the performance of the proposed site planning solution with the hexagonal coverage solution and the minimum power consumption coverage solution. All three methods can achieve full coverage of the target area. As can be seen in Figure 7, the traditional hexagonal coverage method places the center of the target area as the center of the first regular hexagon, using the property of two adjacent regular hexagons to achieve complete overlap to ensure no coverage gaps, expanding outward until the entire target area is covered, as shown in Figure 8. This method is simple to deploy, but due to severe overlapping, it requires a higher system transmission power to achieve full coverage. The minimum power consumption coverage method reduces the coverage radius of the small circles at the boundary of the target area, which, to some extent, reduces the transmission power of the outermost base stations, thus reducing power resource waste. However, this coverage method still has significant  
Figure 6: (**a**) Impact of the radius of the target area on the deployment scheme.