# Performance Analysis of Two-Way Satellite-Terrestrial Relay Network with SWIPT
## 4 Numerical Results  
In this section, numerical simulation results are provided to verify the theoretical analysis and show the impacts of key parameters on the system performance of the two-way satellite-terrestrial relay network. The satellite source node-mobile terminal relay channel coefficients follow Shadowed-Rician fading distribution. The parameters are listed in Table 1 and follow FHS, AS, and ILS, respectively. The user source node-mobile terminal relay channel coefficients follow Rayleigh fading distribution. During a block transmission time, one data packet is transmitted with \(N=512\) symbols. The PS coefficient \(\rho\) is 0.5, which means \(\sqrt{0.5}\) portion of the received signal in the user source node is used for information decoding, and the remaining \(\sqrt{0.5}\) portion of the received signal is harvested. The energy conversion rate \(\eta\) is 0.8. Figure 3 shows the average end-to-end throughput performance versus the average SNR, which is already normalized with power and distance parameters. In Figure 3, the analytical average end-to-end throughput numerical results match the simulation results. Thus, the throughput performance of the SPNC protocol outperforms one of the PNC protocols in the ILS, AS, and FHS cases, respectively. Figure 4 shows the probability of SND protocol versus the average SNR, which is already normalized with power and distance parameters. In Figure 4, the probability of SND protocol numerical results match the simulation results. The probability of SND protocol in the ILS case is significantly higher than the one in AS and FHS cases. This is due to the sharp deterioration of the channel situation. The probability of SND protocol significantly reduces as the gradually increasing of average SNR. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Shadowing** & \(\mathbf{b}\) & \(\mathbf{m}\) & \(\mathbf{\Omega}\) \\ \hline Frequent heavy shadowing (FHS) & 0.063 & 0.739 & 0.000897 \\ Average shadowing (AS) & 0.126 & 10.1 & 0.835 \\ Infrequent light shadowing (ILS) & 0.158 & 19.4 & 1.29 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Land Mobile Satellite channel parameters. Figure 5 shows the average end-to-end throughput performance in AS case versus the average SNR with different PS coefficients \(\rho\), which is already normalized with power and distance parameters. In Figure 5, the probability of SND protocol numerical results match the simulation results. The average end-to-end throughput performance in the AS case significantly increases as the PS coefficients \(\rho\) increase from 0.4 to 0.5 and 0.6. This is due to that the user source node spends more receiving signal energy on information detection, which increases the SNR of user source node during the second time slot. Figure 4: Probability of SND protocol versus the average SNR performance of SPNC protocol in PS aided two-way satellite-terrestrial relay network with ILS, AS, and FHS. Figure 3: Average end-to-end throughput performance versus the average SNR performance of SPNC and PNC protocols in PS aided two-way satellite-terrestrial relay network with ILS, AS, and FHS. In Figures 6 and 7, we assume \(P_{1}=P_{R}=43\) dBm, \(P_{2}=27\) dB. The distance from the satellite source to the mobile terminal is 300 km, and the distance from the user source to the mobile terminal is randomly varying and no more than 50 m. The energy conversion rate \(\eta\) is 0.8. Figure 6 shows the average end-to-end throughput performance versus different PS coefficients \(\rho\). The throughput performance of the SPNC protocol outperforms one of the PNC protocols in ILS, AS, and FHS cases, respectively. The average end-to-end throughput performance in three cases significantly increases as the PS coefficient increases. This is because the user source node spends more receiving signal energy on information detection, which increases the SNR of the user source node during the second time slot.