# Co-Channel Interference Suppression for LTE Passive Radar Based on Spatial Feature Cognition
## 4 Simulation Analysis
We vary the antenna array element number from 4 to 16. For each element number, 100 Monte Carlo simulations are conducted and the detection probability of the target is counted. If the energy of the target is 5 dB above the interference floor after the final cancellation loop, then we declare the detection of the target. The detection probability when the traditional methods are used to suppress the interference is also calculated. The simulation results are shown in Figure 9.0  
Figure 15a shows the results when all the interference signals are from the sidelobe of the surveillance beam. It can be seen that the proposed method can get much better target detection probability than the traditional methods for all the array element numbers. It can get a detection probability of above 0.9 when the antenna array element number exceeds 12. However, the traditional methods can only get a detection probability of less than 0.5 for most of the cases. This shows that the proposed method can adequately cancel the DMI and co-channel interference from the BS-IoO and CCBSs, whereas the cancellation of those interference signals is not sufficient when using the traditional methods. Figure 15b shows the results when some of the co-channel interference signals are from the main lobe of the surveillance beam. It can be seen that in this circumstance the detection probability obtained by all the methods degrades. However, the proposed method still has  
Figure 9.1 Cross-correlating result at cancellation loop 4, (a) spatial spectrum reconstruction results, (b) cross-correlation results. Figure 9.2 Cross-correlating result at cancellation loop 3, (a) spatial spectrum reconstruction results, (b) cross-correlation results. a detection probability of above 0.8 when the antenna array element number exceeds 12. The detection probability obtained by the traditional methods degrades significantly, and it is smaller than 0.2 for all the array element number cases. In the following, we fix the antenna array element number to 16 and vary the number of CCBSs to see the detection performance of the target obtained by the proposed and traditional methods. The number of the CCBSs varies from 0 to 9. For each CCBS number, 100 Monte Carlo simulations are conducted. The simulations results are shown in Figure 9.3  
Figure 16a shows the results when all the interference signals are from the sidelobe of the surveillance beam. It can be seen that when the number of the CCBSs is zero, i.e., there is only the DMI from the BS-IoO and no co-channel interference, the proposed and traditional methods get a similar detection probability. As the CCBS number increases, the detection probability from the proposed and traditional methods decreases. This is because the interference signals become severe when the CCBS number increases. However, the detection probability degrades significantly for the traditional methods and it is smaller than 0.3 when the number of CCBSs exceeds 1. The proposed method still gets good detection probability, above 0.8 for all the CCBS number cases. Figure 16b shows the results when some of the interference signals are from the main lobe of the surveillance beam. It can be seen that the traditional methods degrade severely when there exists CCBSs, and for most cases the target is not detectable because the SNR of the target is smaller than 5 dB. This shows that the traditional methods have very limited ability to handle the case when the interference signals are from the main lobe of the surveillance beam. The proposed method can still get good detection performance and the  
Figure 9.4 Comparison of interference suppression performance under different number of CCBSs, (**a**) interference from the sidelobe, (**b**) interference from the main lobe. Figure 9.5 Comparison of interference suppression performance under different number of antenna arrays, (**a**) interference from the sidelobe, (**b**) interference from the main lobe. detection probability is above 0.8 for most of the CCBSs cases.