# UAV Dynamic Non-Terrestrial Transmission Channel Analysis Based on SSCM-RT Model
## 3 SSCM-RT Channel Model
### SSCM-RT Channel Model Simulation  
In this paper, the path loss is utilized as a metric to assess the viability of the SSCM-RT model. Its direct path, multipath, and all other paths are all taken into account, and their respective path losses are compared with those of other models. Assume that the high-altitude UAV is stationary and the low-altitude UAV is located at an altitude of 150 m and moves in a circle with a radius of 100 m. The frequency is 40 GHz and the bandwidth is 800 MHz. The observation of its first-order reflecting rays, Lambert scattering rays are set in the ray tracing model. The UAV is thought to be made of aluminum, which has a real permittivity of 2.15 and a loss tangent of 0.008 in this scenario. The UAV model utilized for the RT part of the simulation is shown in Figure 5.  
Except for the direct path, all of the multipaths in the RT part simulation are scattering components. The number of rays is between 15 and 20, as depicted in Figure 6. The result shows symmetry. As a result, the channel has more scattering components and is dominant in this scenario. This further exemplifies the necessity for the ray tracing model. In the study of this UAV channel, the path loss of direct path, multipath, and all paths are compared, respectively. In the simulation, when using the SSCM-RT hybrid model, \(d_{2}\) is assumed to be 100 m. The simulation results are shown in Figure 7 and Table 2. Since the measured data for this scenario is challenging, RT simulation results are used as a point of reference. Figure 5: The UAV model used for the RT part of the simulation. The blue point is the receiver of antenna. Figure 6: Number of rays in motion. Figure 7: _Cont._  
When using the results of the ray-tracing-only model as a reference, as shown in Figure 7, the path loss values of the SSCM model are generally smaller due to its error in describing the channel conditions in the near\(-\)field. When the T\(-\)R distance is smaller, the findings of the SSCM-RT model for the direct path outperform those of the cascaded channel model in reference [15] and the GSCM model from 3 GPP TR 38.901 and are closer to the simulation results of the RT model. As the average path loss of the multipath components is utilized as the observation result, the results of the SSCM-RT model for the multipath components are closer to the simulation results of RT when the T\(-\)R distance is large. For all paths, the results of the SSCM-RT model can closely match the outcomes of the deterministic model. Therefore, the validity of the SSCM-RT hybrid channel modeling scheme is shown. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Model** & **Ray Type** & **T-R 500 m** & **T-R 1000 m** & **T-R 2000 m** & **T-R 4000 m** \\ \hline \multirow{4}{*}{SSCM Model} & Direct Path & 108.22 dB & 118.82 dB & 120.49 dB & 131.51 dB \\  & Multipaths & 143.00 dB & 150.09 dB & 156.27 dB & 161.49 dB \\  & All Paths & 142.42 dB & 149.57 dB & 155.73 dB & 160.88 dB \\  & Direct Path & 118.55 dB & 124.57 dB & 130.59 dB & 136.61 dB \\ RT Model & Multipaths & 146.17 dB & 152.12 dB & 158.12 dB & 164.14 dB \\  & All Paths & 144.54 dB & 150.50 dB & 156.50 dB & 162.52 dB \\  & Direct Path & 110.29 dB & 119.40 dB & 121.00 dB & 131.63 dB \\ Simple Porrate Model & Multipaths & 143.64 dB & 150.29 dB & 156.37 dB & 161.56 dB \\  & All Paths & 142.84 dB & 149.67 dB & 155.77 dB & 160.93 dB \\
3 GPP-GSCM Model & Direct Path & 130.91 dB & 132.00 dB & 133.19 dB & 134.38 dB \\  & Direct Path & 118.61 dB & 129.21 dB & 130.84 dB & 141.89 dB \\ SSCM-RT Model & Multipaths & 142.38 dB & 149.80 dB & 157.91 dB & 163.17 dB \\  & All Paths & 143.15 dB & 150.84 dB & 156.98 dB & 161.87 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of path loss of different channel models. Figure 7: Comparison of path loss by using different channel models. (**a**) direct path; (**b**) multipaths; (**c**) all paths. According to Equation (8), \(\frac{d_{1}}{d_{2}}\) will have an impact on the accuracy of the results of the SSCM-RT hybrid channel modeling.