Modification of Synthetic Filtered Output for PSL Reduction in DFT‐Spread OFDM MIMO Radar Using Doppler‐Tolerant Extended Space‐Time Coding

This letter proposes a novel approach for designing Doppler‐tolerant space‐time coding (STC) that extends the phase‐shifted Alamouti scheme by leveraging the fast‐time Doppler resilience characteristics of phase sequences, such as the Frank sequence. We investigate the performance of the proposed STC in mitigating unwanted signals at the matched filter output in discrete Fourier transform spread orthogonal frequency division multiplexing (DFT‐spread OFDM) radar systems, which suffer from limited waveform diversity. Unlike traditional methods, we incorporate cyclically shifted versions of fast‐time Doppler‐resistant sequences directly into the Alamouti block elements. This design promotes orthogonality among all transmitters. Furthermore, by carefully considering the transmission timing of different waveforms on different antennas, the proposed method reduces side lobes in the synthetic filtered output across various Doppler shifts, thereby improving the ratio of the desired signal to unwanted sidelobe energy.