Frequency-Domain Differential Interference Cancellation for Full-Duplex OFDM ISAC Systems

The application of in-band full-duplex (IBFD) integrated sensing and communications (ISAC) systems for higher spectral efficiency and lower sensing latency has received increasing interest in recent years. In the IBFD mode, however, the transmitted signal causes severe interference at the receiver. This paper proposes a novel low-complexity frequency-domain differential interference cancellation (F-DIC) scheme for IBFD orthogonal frequency-division multiplexing (OFDM) ISAC systems. Without the need for channel state information (CSI), the proposed F-DIC method cancels the static interference and extracts the moving target echo signals by leveraging the invariant property of the interference. After the residual interference evaluation of the proposed method, the interference cancellation ratio of the F-DIC scheme is analyzed, and a closed-form formula of the target detection probability under the Neyman-Pearson (NP) criterion for OFDM ISAC systems based on the proposed scheme is also derived. Simulation results show that the proposed F-DIC method with promising low computational complexity performs similarly compared with the conventional frequency-domain interference cancellation method based on least squares (LS) and recursive least squares (RLS) algorithms.