## 4 Simulation Results and Analysis
In terms of receiving detection schemes, as heterodyne detection belongs to coherent detection, and under the same system average signal-to-noise ratio \(\overline{\gamma}\) conditions, heterodyne detection will obtain lower system outage probability values than incoherent IM/DD detection because coherent detection mechanism can effectively suppress noise and fading effects by utilizing the phase and frequency information of the signal, particularly showing stronger performance in composite fading channels (such as strong turbulence and large pointing errors). In addition, the theoretical calculation values of the system are in good agreement with the MC simulation values, and the asymptotic value of the outage probability at high SNR also basically coincides with the theoretical value at the corresponding signal-to-noise ratio. This indicates the correctness of the closed form formula derivation results related to the theoretical and asymptotic values of the system outage probability mentioned above. Figure 3 shows the theoretical and MC simulation values of the outage probability of the hybrid dual-hop RF-UWOC relay communication system under different UAV hovering heights and horizontal distances, as a function of the average SNR \(\overline{\gamma}\). Similarly, the solid line in the figure represents IM/DD detection, the dotted line represents heterodyne detection, the dashed line represents asymptotic value curve, and the asterisk represents MC simulation value. Set the horizontal and vertical distances between UAV and R in the RF link as follows \((r,h)\): \((300\) m, \(400\) m), \((900\) m, \(2000\) m), \((3000\) m, \(4000\) m), \((\)Correspond to the red, blue, and pink curves in the figure respectively.) corresponding to the linear distance \(500\) m, \(2193\) m, \(5000\) m between UAV and R (generalized K-fading coefficient: \(m=1.0,k=1.9\)), pointing error \(\xi=4.0\) of the second hop UWOC link, underwater transmission distance \(d=20\) m, and turbulence scintillation index \(\sigma_{l}^{2}=0.1074\). From  
Figure 2: The variation curve of outage probability of RF-UWOC hybrid double hop system with average SNR under different Generalized K distribution parameters. the simulation results in Figure 3, it can be seen that under the condition of fixed UWOC link simulation parameters, the outage probability of the hybrid double hop system will show a downward trend in performance due to the increase in the hovering height of the UAV as a floating base station in the RF link and the horizontal distance from the relay node R. This is mainly due to the increase in the straight-line distance \(d_{UR}\) from UAV to R, which leads to an increase in road loss \(L_{UR}\). However, under the same road loss conditions, outage probability still decreases with the increase in the average signal-to-noise ratio, indicating that increasing the received signal-to-noise ratio is still beneficial for improving system performance. Similarly, in terms of receiving detection schemes, as heterodyne detection belongs to coherent detection, under the same system average signal-to-noise ratio conditions, heterodyne detection will obtain lower system outage probability values than incoherent IM/DD detection. Figure 4 shows the theoretical outage probability and MC simulation values of a hybrid dual-hop RF-UWOC relay communication system under different intensities of ocean turbulence (turbulence scintillation index \(\sigma_{I}^{2}=0.1074/0.2066/0.4548\), Correspond to the pink, blue, and red curves in the figure respectively) experienced by the second hop UWOC link with fixed channel parameters of the first hop RF link, as a function of the average signal-to-noise ratio. At this point, the horizontal and vertical distances between UAV and R in the first hop RF link are set as follows \((r,h)\): \((900\ \mathrm{m},2000\ \mathrm{m})\); the coefficient values that obey generalized K-fading are \(m=2.0,k=2.6\), weak pointing error \(\xi=4.0\) of the second hop UWOC link; underwater transmission distance \(d=20\ \mathrm{m}\).