## 4 System Performance Discussion
### Performance Comparison Results  
Unlike traditional MIMO radar, single link RF MIMO radar first generates control signals through two random digital signals. One of the signals is the control signal of the initial orthogonal basis, and the result of the two signal XOR operations controls the opening direction of the SPDT switch. In this work, two pseudorandom codes were used (PN15 and PN9). The emission waveform is reflected by the radar target, which can be considered as the modulation process that carries the speed and distance information of the radar target on the transmitting waveform. The clutter interference in the channel adopts Rayleigh clutter, which is added to the transmitting signal by the clutter module. At the receiving end, the single link MIMO system can recover the two pre-modulated signals with a low bit-error rate. The restored signals will enter the correct matching filter. Then, we can filter out the unwanted clutter and noise in the reflected signal and get the velocity and distance information of the target through FFT. The CA-CFAR algorithm was adopted to get the result of the detected target. Finally, the Monte Carlo method was used to calculate the detection probability of the system. The sampling frequency and the working frequency of the simulation were 20 MHz and 10 GHz, respectively. The baseband transmission with 60 MHz signal was up-converted to the middle frequency  
Figure 10: Schematic diagram of the pulse compression process. The two broad pulses are compressed into two narrower pulses through a pulse compression process, with one path representing the reference signal and the other path representing the received signal. of 2.9 GHz. The repetition rate and the width of the pulse were 20 kHz and 500 ns, respectively. The simulation system setup in SystemVue software is shown in Table 2.  
As for the Swerling 0 target with radar distance of 9000 m and speed of 270 m/s, the target velocity and target distance of the two radar systems can be acquired from Figure 11. The traditional MIMO radar system can be acquired by replacing the single-link MIMO module with the module shown in Section 3. The results are compared in Table 3 with the system setup shown in Table 2.  
It is not difficult to find that the ideal detection capability of target distance and velocity in single RF link MIMO radar and normal MIMO radar is basically the same. For both the detection of target velocity or the target distance, the error rate is kept in a small range with a slight difference, which is due to the calculation accuracy of the simulation platform. The detection speed of the two kinds of radars differ by only one sampling point, which can be seen as a calculation error and can be effectively reduced by increasing the number of FFT. In summary, the proposed single RF link MIMO radar can achieve the desired effect, as expected. The detection probability of radar was measured by Monte Carlo method. \(D(t)\) is the indicating function that represents the result of target detection. If it equals 0, the target is not found, and 1 denotes that the target is detected. After 1000 simulations, the detection probability of single RF link MIMO radar and traditional MIMO radar were both above 99%, which verifies the correctness of the single RF link MIMO radar system. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & **Sampling** & **Baseband** & **Intermediate** & **Operation** & **Pulse** & **Pulse Width** \\  & **Rate** & **Frequency** & **Frequency** & **Frequency** & **Repetition** & \\ \hline
**Value** & 20 MHz & 60 MHz & 2.9 GHz & 10 GHz & 20 kHz & 500 ns \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Simulation system parameters setup. Figure 11: Single-link radiofrequency (RF) MIMO radar system proposed in this paper. The system consists of signal generator module, control signal, signal processing module, up-conversion module, clutter module, single-link MIMO module, and receiver module.