FBMC-Chirp Waveforms for Joint Wireless Communication and SAR Imaging

In recent years, joint wireless communication and Synthetic Aperture Radar (SAR) imaging has received extensive attention. The realization of this concept remains a significant challenge. For communication and SAR, they have conflicting requirements on waveforms. The state-of-the-art solutions are based on the Orthogonal Frequency Division Multiplexing (OFDM) techniques. However, OFDM waveforms are sensitive to the Doppler frequency. Even worse, their unavoidable Cyclic Prefix (CP) would introduce false peaks into SAR images. To be insensitive to frequency bias and free of CPs, Filter Bank Multicarrier (FBMC) waveforms with stepped frequency chirp and Offset Quadrature Amplitude Modulations (OQAM) are proposed in this paper. Particularly, stepped frequency chirps, which have been optimally weighted for SAR imaging, are interleaved into FBMC subcarriers as pilots. Meanwhile, the channel changes can be obtained from these pilots for communication equalization. Moreover, concerning the intrinsic interference of imaginary parts between pilots and OQAM symbols, compensation algorithms are introduced. With the proposed waveform schemes, the identical frequency band can be utilized for data transmission while performing high-resolution SAR imaging. Theoretical analysis and simulation results demonstrate that the proposed waveform scheme is feasible.