# Security Performance Analysis of Full-Duplex UAV Assisted Relay System Based on SWIPT Technology
## 4 Experimentation and Simulation
When the environmental parameters \(\omega_{1}=4.88\), \(\omega_{2}=0.43\), it corresponds to a suburban environment; when the environmental parameters \(\omega_{1}=9.61\), \(\omega_{2}=0.1\), the environment is urban; when the environment is a dense urban area, the environmental parameters \(\omega_{1}=12.08\), \(\omega_{2}=0.11\); when the environment is a high-rise building, the environmental parameters \(\omega_{1}=27.23\), \(\omega_{2}=0.08\). From the (b) graph in Figure 6, it can be seen that the system's secrecy outage probability is minimized in the environment of a high-rise city. This is because in the environment of high-rise buildings, the fading of the system will increase, but at this time, the interference signal sent by the UAV relay node U to the UAV eavesdropping node E belongs to the high-altitude transmission, which is less affected, so the eavesdropping channel capacity will become smaller, the SOP of the system decreases, and the security of the system is enhanced. Figure 5: SOP versus power allocation factor \(\lambda\) for different eavesdropping transmission rate thresholds \(R_{E}\). From Figure 7, it can be seen that when the \(H_{1}\) normalized height is 1, the SOP of the system decreases as the height of the eavesdropping UAV increases from 1.3 to 1.4, causing an increase in the security performance of the system. This is because when the eavesdropping UAV height \(H_{2}\) increases, the probability of line-of-sight propagation of the eavesdropping signal transmission increases, and at the same time, the eavesdropping interference decreases, which reduces the security performance of the system. But if it continues to increase \(H_{2}\), it will lead to a higher path loss, which will cause a reduction in the channel capacity of the system's eavesdropping channel link, and the security performance of the system will be enhanced. Figure 8 compares the variation of SOP with the eavesdropping rate threshold \(R_{e}\) for different eavesdropping interference schemes. Scenario 1 is a no interference scenario, where there is no interference signal in the first and second phases of the whole communication system; Scenario 2 is a single interference scenario, where only the destination node sends interference in the second phase; and Scenario 3 is the double interference scenario proposed in this paper, where the relay UAV U is in full-duplex mode and there are eavesdropping interferences in both the first and second phases of the relay communication  
Figure 6: Relationship between SOP and power allocation factor under different environmental parameter conditions. Figure 7: SOP vs. power allocation factor for different eavesdropping UAV altitudes \(H_{2}\). link. From the figure, it can be seen that the size relationship of secrecy outage probability under different eavesdropping interference schemes is: double interference scheme < single interference scheme < no interference scheme, so the relationship of system security performance is double interference scheme > single interference scheme > no interference scheme. For the dual interference scheme proposed in this paper, as \(\lambda\) decreases, for example, A changes from 0.4 to 0.2, the SOP decreases. This is because when the total transmit power is certain, the decrease in \(\lambda\) implies that the jamming signals acting on the eavesdropping node increase; therefore, the SOP of the whole communication link decreases, and the security performance of the system is enhanced, which verifies the relationship between the SOP and \(\lambda\) once again. The results show that the proposed scheme in this paper outperforms the half-duplex UAV scheme as well as the non-interference scheme in terms of security performance.