Cognitive Radar Time-Domain Cooperative Waveform Optimization for ISRJ Suppression

This paper proposes a cognitive optimization method for countering interrupted sampling repeater jamming (ISRJ) using temporal cooperative waveforms in a cognitive radar system. Two radar sites cooperatively transmit orthogonal waveforms, forming long pulses that deceive the jammer into sampling only the protection waveform from Site 2, while leaving the detection waveform from Site 1 unaffected. The orthogonality of the waveforms enables both the jamming and protection signals to be filtered out by the matched filter (MF) corresponding to the detection waveform, thereby achieving effective jamming suppression. Based on this strategy, a Q-learning-based timing optimization method is proposed, with the reward function defined by the difference between the first and second peaks of the pulse compression result. Simulation results demonstrate that the proposed method achieves a jamming suppression gain of up to 30 dB compared to existing approaches, and maintains stable performance in complex multi-target and multi-interference scenarios. Furthermore, the algorithm exhibits low sensitivity to jammer-to-signal ratio (JSR) variations, confirming its robustness and practicality in dynamic ISRJ environments.