Preamble-Aided Receiver for OFDM Recovery Under Structured FMCW Interference in Co-Channel Sensing–Communication Systems

Co-channel operation of frequency-modulated continuous-wave (FMCW) sensing and orthogonal frequency-division multiplexing (OFDM) communication can severely disrupt burst synchronization and payload recovery when both waveforms overlap in time and frequency. This paper presents a preamble-aided receiver that exploits communication-side occupancy information to constrain structured FMCW interference estimation. A known auxiliary preamble estimates the OFDM burst position and occupied temporal support, allowing communication-free observations to guide FMCW reconstruction. Dominant sensing components are estimated from range–Doppler structure and removed through regularized parametric cancellation. Residual mismatch is then suppressed using a low-dimensional subspace learned from communication-free observations and applied under the preamble-derived occupancy constraint. The compensated signal is subsequently processed by synchronization, equalization, decoding, and cyclic redundancy check (CRC) verification. In a representative partial-overlap scenario with an input communication-side signal-to-interference ratio (SIR) of −24.30 dB, the proposed receiver achieves a 23.98 dB beat-domain cancellation gain over communication-free observations, zero-sample burst-localization error, and successful recovery of a 217-byte payload with a zero bit error rate (BER) and successful CRC verification. Reduced configurations fail to recover the payload. These results provide a simulation-based proof-of-concept for communication-informed FMCW interference suppression and OFDM recovery.