| Combining full duplex technology and digital beamformiing technology together,full duplex aiTay(FD-ARRAY)systems have broad application prospects because of its higher spectral efficiency and advantages of array systems.Among the current literature about full duplex,scholars mainly focus on self-interference suppression without considering the Scene with strong external interference.In this paper,the interference suppression technology is studied,so as to guarantee that full duplex system can keep normal communication in the environment with external interference.First,two algorithms based on minimum variance distortionless response(MVDR)criterion,namely cascading MVDR algorithm and joint MVDR algorithm,are proposed to suppress both self-interference and external interference at the receiving end.By analyzing the self-interference suppression performance and external interference suppression performance,the two schemes are proved to be effective.Then,considering that the application environment may be non-stationary,the recursive least square structure for joint MVDR algorithm is proposed.What's more,a robust algorithm for steering vector mismatch is proposed,which can significantly improve the performance of the algorithm when it comes to such a parameter mismatch.Second,a transmit beamforming scheme which aims at minimizing the coupled self-interference power is proposed.The algorithm can minimize the self-interference power at the receiving end,of course,under the premise of ensuring the constant beam width of the main lobe,target direction gain and sidelobe level constraints.Third,a simple FD-ARRAY system is built to verify the interference suppression algorithms at the receiving end.The test results show shat the two algorithms can achieve 37.5dB suppression for self-interference and 58.5dB suppression for external interference.In conclusion,the algorithms are effective in suppressing self-interference and external interference. |
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