Joint 2‐D LFM Modulation and Mismatched Filter Design in Dual‐Function Radar‐Communication System

Targeting military‐grade dual‐function radar‐communication (DFRC) systems, OFDM‐based waveforms are rendered unsuitable due to their high peak‐to‐average power ratio and limited sensing precision. Although linear frequency modulation (LFM) waveform is the bedrock of such radar systems for constant‐envelope and Doppler resilience, the data rate is inherently low. To bridge this gap, we propose an LFM‐based 2‐D modulation scheme that independently modulates information bits onto both the initial frequency and chirp rate of each pulse. This approach breaks the conventional trade‐off, delivering a substantially higher data rate whilst strictly maintaining the constant‐envelope property essential for high‐power radar amplification. However, this modulation induces pulse agility, severely degrading radar performance through range sidelobe modulation (RSM) and inconsistent mainlobe resolution. To combat this, we co‐design a computationally efficient mismatched filter bank using adaptive common‐bandwidth cyclic algorithm. The algorithm adaptively synthesises a spectrum‐compatible reference template by exploiting the common spectral features of the waveform set, effectively suppressing RSM and resolving resolution ambiguity with minimal SNR loss. Simulations confirm our joint design achieves a higher data rate than one‐dimensional LFM schemes and nearly eliminates RSM effects, thereby fulfilling the simultaneous demand for reliable data links and high‐precision target detection in next‐generation military DFRC systems.