# Bidirectional Atmospheric Channel Reciprocity-Based Adaptive Power Transmission
## 3 Simulation and Investigation
### The BER Performance of Proposed Adaptive Power Transfer Technique
Although channel reciprocity gradually declined in channels with increased turbulence intensity, the performance of signal transmission was also influenced by the quantity of noise present in the channel. Under different background noise conditions, the reciprocity of the turbulent channel was also attenuated to different degrees. The values of the three tests under the experimental conditions were specifically shown in Table 1, where the channel reciprocity for the turbulence channel of \(\sigma^{2}=0.0596\) was \(\rho\leq 0.5998\) for \(\rm{N_{b}}\leq 10\) dB, and \(\rho\leq 0.8803\) for the turbulence channel of \(\sigma^{2}=0.5250\). Based on Figures 11 and 12, it was not difficult to see that the CR-APT technique lost its ability to suppress the effects of fading from atmospheric turbulence only when larger background noise was added to the turbulence channel. Figure 8: BER performance of the three techniques in different turbulent channels when \(\rm{N_{b}}=25\) dB. (**a**) \(\sigma^{2}=0.0596\), (**b**) \(\sigma^{2}=0.5250\). Figure 9: BER performance of the three techniques in different turbulent channels when \(\rm{N_{b}}=20\) dB. (**a**) \(\sigma^{2}=0.0596\), (**b**) \(\sigma^{2}=0.5250\). Combining the aforementioned tests demonstrates how susceptible to background noise the CR-APT method is. The performance was dependent on the channel's turbulence intensity in the situation of low background noise; the higher the performance, which outexecuted both the ATD and FTD approaches, the smaller the channel's turbulence intensity. The ultimate performance was influenced by the interaction of turbulence strength and background noise, which resulted in a drop in channel correlation as background noise levels rose. When the turbulence channel reciprocity was \(\rho\geq 0.8\) and the background noise level, the performance was improved by \(\rho\geq 0.8\) and the background noise level was improved by \(\rho\geq 0.8\). \begin{table}
\begin{tabular}{c c c c c} \hline \(\mathbf{\sigma^{2}}\) & \(\mathbf{N_{b}}\)**(dB)** & \(\mathbf{\rho_{1}}\) & \(\mathbf{\rho_{2}}\) & \(\mathbf{\rho_{3}}\) \\ \hline  & 30 & 0.9912 & 0.9912 & 0.9912 \\  & 25 & 0.9730 & 0.9730 & 0.9730 \\  & 20 & 0.9214 & 0.9215 & 0.9214 \\
0.0596 & 15 & 0.8000 & 0.8000 & 0.8001 \\  & 10 & 0.5996 & 0.6000 & 0.5999 \\  & 5 & 0.3886 & 0.3887 & 0.3882 \\ \hline  & 30 & 0.9986 & 0.9986 & 0.9986 \\  & 25 & 0.9954 & 0.9954 & 0.9954 \\
0.5250 & 20 & 0.9858 & 0.9858 & 0.9856 \\
15 & 0.9570 & 0.9570 & 0.9570 & 0.9570 \\  & 10 & 0.8803 & 0.8802 & 0.8803 \\
5 & 0.7220 & 0.7219 & 0.7219 \\ \hline \end{tabular} \(\mathbf{\rho_{1}}\), \(\mathbf{\rho_{2}}\), and \(\mathbf{\rho_{3}}\) represent three channel reciprocity measurements. The \(\mathbf{\rho}\) used within the article was the average of the three times.  
\end{table} 
Table 1: Three channel reciprocity measurements with different background noise added for two turbulent channels. Figure 11: BER performance of the three techniques in different turbulent channels when \(\mathrm{N_{b}}=10\) dB. (**a**) \(\sigma^{2}=0.0596\), (**b**) \(\sigma^{2}=0.5250\). Figure 10: BER performance of the three techniques in different turbulent channels when \(\mathrm{N_{b}}=15\) dB. (**a**) \(\sigma^{2}=0.0596\), (**b**) \(\sigma^{2}=0.5250\). noise \(\rm{N_{b}}\geq 10\) dB, the CR-APT approach provided great BER with little SNR. However, the CR-APT approach could only be used with very little background noise when there was considerable turbulence intensity.