# Low-Altitude Sensing Model: Analysis Leveraging ISAC in Real-World Environments
## 4 Performance Verification and Analysis
### Single Base Station OTA Test  
First, the target was designed to move away from the AAU along the antenna's normal direction (OA direction) at a speed of 1 m/s, starting from the minimum distance supported by the system. The distance \(R^{+}_{\text{min1}}\) where the target stably appeared and the distance \(R^{+}_{\text{max1}}\) where the target was stably lost were recorded. Then, the target moved towards the AAU  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**System** & **Frequency (GHz)** & **Bandwidth (MHz)** & **Band No.** & **Duplex Mode** \\ \hline
5G-A & 26 & 20 & n257 & TDD \\ \hline \hline \end{tabular}
\end{table}
Table 1: Carrier configuration.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Notation** & **Parameter** & **System Value** \\ \hline \(\sigma\) & RCS of the target & 0.01 m\({}^{2}\) \\ \(\text{P}_{\text{t}}\) & Transmission power & 40 dB \\ \(\text{G}_{\text{r}}\) & Reception antenna gains & 35 dB \\ \(\text{G}_{\text{t}}\) & Transmission antenna gains & 35 dB \\ n & Total cumulative number of signals & 64 \\ \(\tau\) & Total transmission duration of signals & 4 \(\mu\)s \\ L & RV processing loss & 4 dB \\ N & Number of neighboring stations & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 2: System parameters.  
Figure 10: Single base station 3D sensing model for the OTA test.  
Figure 9: OTA environment.  
along the normal direction at a speed of 1 m/s, starting from the maximum supported distance. The distance \(R^{-}_{\text{max1}}\) where the target stably appeared and \(R^{-}_{\text{min1}}\) where the target was stably lost were recorded. These steps were repeated to obtain \(R^{+}_{\text{min2}}\), \(R^{+}_{\text{max2}}\)+, \(R^{-}_{\text{max2}}\), and \(R^{-}_{\text{min2}}\). The minimum sensing distance \(R_{\text{min}}\) and maximum sensing distance \(R_{\text{max}}\) were then calculated as follows:  
\[R_{\text{min}}=\frac{R^{+}_{\text{min1}}\!+\!R^{+}_{\text{min2}}\!+\!R^{-}_{ \text{min1}}\!+\!R^{-}_{\text{min2}}}{4} \tag{13}\]  
\[R_{\text{max}}=\frac{R^{+}_{\text{max1}}\!+\!R^{+}_{\text{max2}}\!+\!R^{-}_{ \text{max1}}\!+\!R^{-}_{\text{max2}}}{4} \tag{14}\]  
The base station sensing results are shown in Table 3.  
The average of the nearest point along the OA direction was 0.04 m, and the farthest point was 1000.22 m. This resulted in a discrepancy of 0.02% from the theoretical range, which could be considered in line with the theoretical expectations.  
Next, the angle test was conducted at a distance of 300 m along the OA direction from the AAU. The AAU turntable was rotated horizontally until the target was no longer sensed. The current horizontal angle of the turntable was recorded as \(\theta_{\text{horizontal}}\). The horizontal angle of the AAU turntable was then restored to the OA direction. The AAU turntable was rotated vertically downwards until the target was no longer sensed, and the current vertical angle of the turntable was recorded as \(\theta_{\text{vertical}}\). The maximum horizontal and vertical angles were given as shown in Table 4.  
It can be seen that the horizontal angle differed from the theoretical value by only 0.08%, while the vertical angle differed by 0.7%. The main reason for the discrepancy was the accuracy of the turntable, which could be considered in line with the theoretical expectations.