# Secure Beamforming Design for UAV-Empowered Integrated Sensing and Communication
## 4 Simulation Results and Performance Analysis  
To validate the efficacy of the proposed algorithm, MATLAB simulations were conducted. In the simulation, we consider a 1 km \(\times\) 1 km area, with \(K=2\) legitimate ground communication users. We first conduct simulations for the \(J=1\) single eavesdropper scenario and then extend our analysis to the case of multiple eavesdroppers. We begin by examining the single eavesdropper scenario. The legitimate users are located at \((700,400,0)\) and \((800,600,0)\), and the single eavesdropper is located at \((150,500,0)\). Unless otherwise specified, the UAV flight altitude is \(H=100\) m, the maximum transmit power is \(P_{\max}=0.3\) W, and it has four antennas. The communication threshold for all legitimate users is \(\Gamma_{k}^{\mathrm{com}}=7\) dB, and the beam pattern gain threshold is \(\Gamma_{e}^{\mathrm{sen}}=-18\) dBm. The received noise power for each legitimate user and the eavesdropper is set to \(\sigma_{k}^{2}=\sigma_{e}^{2}=-110\) dBm, and the channel power gain at the reference distance \(d_{0}=1\) m is \(\beta=-60\) dB. To assess the performance of the proposed algorithm, it is benchmarked against the following three algorithms:  
* Comparison Algorithm 1: Only optimize the UAV transmit beamforming without optimizing the UAV position. * Comparison Algorithm 2: In this algorithm, the UAV transmitted signal contains only communication signals without dedicated sensing signals. Similar to Algorithm 1, it optimizes both the UAV transmit beamforming and the UAV position. * Comparison Algorithm 3: The UAV transmitted signal contains only communication signals without dedicated sensing signals. It optimizes the UAV transmit beamforming but not the UAV position. Figure 2 illustrates the convergence behavior of the proposed algorithm. It is evident that the maximum eavesdropping SINR decreases rapidly with the number of iterations, achieving convergence by the fourth iteration. Figure 3 shows the variation of the maximum eavesdropping SINR with increasing communication thresholds for legitimate users, where the sensing threshold is \(-18\) dBm. The figure clearly demonstrates that the maximum eavesdropping SINR increases monotonically with the communication threshold. This is because the increase in the communication threshold leads to a higher demand for communication resources, which, under the condition of an unchanged sensing threshold, inevitably reduces the system's security. Furthermore, in Figure 3, the data clearly indicate that the proposed algorithm surpasses the other three algorithms in terms of security performance. By comparing the proposed algorithm with Algorithm 1, it can be seen that optimizing the UAV position reduces the maximum eavesdropping SINR and improves the system's security performance. By comparing the proposed algorithm with Algorithm 2, it can be seen that although the dedicated sensing signal transmitted by the UAV affects the communication SINR of legitimate users, it can more effectively improve the system's security under the premise of ensuring sensing performance. This is because dedicated sensing signals more easily meet the system's sensing requirements, thereby allocating resources to ensure system security. As the communication threshold increases, the performance differential between the proposed algorithm and the comparison algorithms narrows over time. This occurs as the elevated communication threshold restricts the UAV positional freedom, consequently reducing the performance disparity between the proposed algorithm and Algorithm 1. Algorithm 3 exhibits the highest eavesdropping SINR because it solely optimizes beamforming for communication signals without incorporating specialized sensing signals or optimizing UAV positions. Consequently, its eavesdropping SINR is higher compared to other algorithms. Figure 4 shows the variation of the maximum eavesdropping SINR with increasing sensing thresholds, where the communication threshold is 7 dB.