Efficient Radar Signal Processing in ISAC: Optimizing FFT Operations with Circulant Matrix

Integrated Sensing and Communication (ISAC) has emerged as a promising approach to improve resource efficiency in wireless systems, particularly for radar and communication functions. However, traditional methods for orthogonal frequency division multiplexing (OFDM)-based radar processing often involve complex two-step fast Fourier transform (FFT) operations, resulting in high computational demands and hardware resource consumption. To address these challenges, this paper proposes a simplified radar signal processing method tailored for ISAC systems, which transforms the two-step FFT process into a more efficient matrix-vector multiplication using a circulant matrix. Through numerical simulations and hardware resource analysis, it is demonstrated that the proposed approach achieves substantial reductions in computational burden. Compared to the traditional two-step FFT method, the proposed algorithm achieves a minimum reduction of 33.59% in hardware multiplier consumption when the matrix dimension is less than 64. This technique enables more efficient radar and communication processing in ISAC systems, making it more viable and cost-effective and paving the way for more advanced radar and communication integration in future ISAC applications.