Joint Design of Transmit Signals and Mismatched Filters for ISRJ Suppression in Dual Function Radar-Communication Systems

Future dual function radar-communication (DFRC) systems must be resilient to emerging forms of radar jamming. Interrupted sampling repeater jamming (ISRJ) exploits the temporal structure and coherence properties of DFRC signals, making the jamming signals highly similar to real target echoes, thereby generating dense false targets and degrading target detection reliability. To address this challenge, this paper investigates the joint design of transmit signals and receive mismatched filters for DFRC systems under ISRJ attacks. We propose an objective function that jointly maximizes the integrated sidelobe to mainlobe ratio of the filtering output of the transmit signal, while minimizing the integrated energy of the filtering output of the jamming signal and its zero-delay peak value. In the communication aspect, we incorporate robustness against imperfect channel state information into the design. To ensure reliable communication performance under channel uncertainty, we incorporate outage-based probabilistic constraints on multi-user interference, ensuring that the interference power at each legitimate user remains below a predefined threshold with high probability. Furthermore, to ensure secure communication and prevent information leakage, we introduce a probabilistic constraint on the cosine similarity between the received signals at the eavesdroppers and the confidential symbol, requiring it to remain below a specified threshold with high confidence. In addition, to improve power amplifier efficiency and mitigate nonlinear effects, constraints on the total energy and peak-to-average power ratio of the transmit signal are enforced. To tackle the resulting nonconvex optimization problem, we develop an iterative solution based on cyclic optimization, Dinkelbach algorithm, and the alternating direction method of multipliers. Simulation results demonstrate that the proposed joint design method can effectively suppress ISRJ while ensuring reliable communication performance.