Research On Passive Radar Related Technique Based On 4G Base Station Signal

With the development of modern science and technology, the traditional radar is threatened increasingly by electronic interference, stealth technology, anti-radiation missiles and low altitude penetration. Passive radar doesn’t transmit signal by itself, but uses an extra illumination sources for target detection and tracking. So, it has good characteristics against these threats. In recent years, passive radar has received more and more interest.Mobile communication signal has the advantage of wide coverage and networking easily. It is an excellent extra illumination source. Passive radar researchers are paying more and more attention to it. The passive radar system based on 4G signal is studied in this thesis. The research works completed are as follows:1. The technical characteristics of 4G mobile communication system is analysed. The LTE signal range and doppler resolution are calculated according to the radar signal analysis theory. The LTE signal ambiguity function is analysed in detail. Then, the reasons for generating side lobes are explained. Moreover, the theoretical power range of passive radar system based 4G signal is calculated by using the bistatic radar equation. At last, the feasibility analysis of passive radar system based on 4G signal is completed.2. Since the target echo signal contains a lot of direct and multipath signal, the suppression technology of the direct signal and multi-path is studied in this thesis. The suppression performance of the LMS algorithm, NLMS algorithm, ECA algorithm and RLS algorithm are analysed and discussed in the passive radar system based on 4G signal. By considering the indicators of suppression ratio of the clutter and convergence rate of the weight, the RLS algorithm is used in this work. Then, the performance of RLS algorithm is proved through the simulation experiment.3. Since a weak target in multiple targets can not detected effectively in the traditional methods, the target detection method based on compressed sensing theory is studied in this thesis. By introducing the compressive sensing theory into the target detection of passive radar, both the strong target and the weak target can be detected successfully in the multiple target sceonario. Simulation results prove the validity of the method used in this thesis. It provides another efficient algorithm for the target detection in the passive radar.