## 6 Results and Analysis  
In this part, the simulation data of the multi-user mixed RF/FSO system under diverse parameters with optimal user interference are presented. Monte Carlo simulations verify the numerical results' accuracy. The FSO link distance is 100 m and the wavelength is 785 nm, the optical wave number \(k=2\pi/\lambda\); \(C_{n}^{2}=10^{-11}\) m\({}^{-2/3}\) is the atmospheric refractive index structure constant of medium turbulence, and the target secrecy rate \(R_{S}=0.01\) nat/s. Furthermore, the Instantaneous SNR of the FSO link is \(\gamma_{RD}=20\) dB, the instantaneous SNR of the RF link is \(\gamma_{SR}=15\) dB, and the instantaneous SNR of the eavesdropping link is \(\gamma_{SE}=-10\) dB. On the RF link, \(d_{SE}=d_{SR}=10\) m, and \(d_{RE}=5\) m. The other parameters are \(\eta=0.8\), \(\rho=0.8\), \(N_{J}=2\), r = 1, a = 1.83, b = 3.94, and \(\xi_{\text{mod}}=0.84\). The specific simulation parameters are shown in Table 1.  
The above parameter values are used in the following simulations. When the generalized Laguerre orthogonal numerical integration method is used, j is considered as 30 in order to make the series converge. The Monte Carlo simulation results confirm the validity of the analytical expressions. The numerical and simulation results are in good agreement, which verifies the accuracy of the proposed expressions. Figure 3 shows the mixed system's SOP as a function of the variation of the RF link's Instantaneous SNR \(\lambda_{SR}\) for diverse numbers of the optimal user's interfering antennas. It can be known that the mixed system's SOP with different number of interfering antennas \(N_{J}\) decreases as the \(\lambda_{SR}\) increases. When \(\lambda_{SR}\)= 30 dB and \(N_{J}=2,4,6\) and 8, the mixed system's SOP are \(9.7\times 10^{-4}\), \(3.0\times 10^{-4}\), \(1.3\times 10^{-4}\) and \(6.9\times 10^{-5}\), respectively. This set of simulation data shows the mixed system's SOP decreases as the number of interfering antennas of the optimal user increases. Therefore, it can be gathered that the mixed system's security performance could be effectively enhanced by enlarging the optimal user interference antennas' number at the source node. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**System Parameters** & **Symbol** & **Value** & **System Parameters** & **Symbol** & **Value** \\ \hline Laser wavelength & \(\lambda\) & 785 nm & Link distance per hop & \(d\) & 100 m \\ Weak turbulence & a & 2.33 & Weak turbulence fading & b & 4.53 \\ positive parameter & & & Medium turbulence & \\ positive parameter & a & 1.83 & fading parameters & b & 3.94 \\ Strong turbulence & a & 1.43 & Strong turbulence & b & 3.53 \\ positive parameter & & & fading parameters & & \\ Electro-optic & \(\omega\) & 0.8 & target secrecy rate & \(R_{S}\) & 0.01 nat/s \\ atmospheric refractive index & & & & \\ structure constant & & & & \\  & & & & \\ Time switching factor & \(\rho\) & 0.8 & & of the FSO link & \(\gamma_{RD}\) & 20 dB \\ the instantaneous SNR & & & Number of & \\ of the RF link & \(\gamma_{SR}\) & 15 dB & interfering antennas & \(N_{J}\) & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Selection of simulation parameters for the mixed RF/FSO system. As the spatial degree of freedom of the optimal user increases with an increase in the number of optimal user interference antennas, the eavesdropping channel quality degrades based on its state information at the eavesdropping node. For the same value of SOP, increasing the optimal user's number of jamming antennas results in lower transmission power for each antenna in the scheme. In addition, the cost of increasing the antennas' number is lower than that of adding jammers outside the mixed RF/FSO system. Increasing the number of jamming antennas provides a good schedule for the design of the optimal user transmitting jamming signals and reducing the power consumption of the source node.