Multi-Block DFT-Spread OFDM for THz-ISAC

The Terahertz (THz) and sub-THz frequency bands hold great promise for next-generation wireless systems, particularly the sixth generation (6G), due to their wide bandwidth, support for high data rates, and enhanced sensing precision in integrated sensing and communication (ISAC) applications. This paper presents a multi-block discrete Fourier transform spread orthogonal frequency division multiplexing (MB DFT-s-OFDM) waveform, suitable for THz-ISAC systems. We evaluate the performance of the proposed waveform using two types of receivers: least squares (LS) and matched filter (MF). Our results demonstrate that MB DFT-s-OFDM achieves a lower peak-to-average power ratio (PAPR) compared to OFDM and improves sensing accuracy over DFT-s-OFDM for detecting multiple targets, while maintaining robust communication performance in typical THz channels. Additionally, the MF receiver demonstrates high accuracy in detecting strong targets across all waveforms. However, the LS receiver proves more effective for detecting a weak target in the presence of a strong target where in this case the MB DFT-s-OFDM waveform outperforms the DFT-s-OFDM waveform.