An Energy-Efficient DFT-Spread Orthogonal Time Frequency Space System for Terahertz Integrated Sensing and Communication

Terahertz (THz) integrated sensing and communication (ISAC) is a promising interdisciplinary technology that realizes simultaneously transmitting Terabit-per-second (Tbps) and millimeter-level accurate environment or human activity sensing. However, both communication performance and sensing accuracy are influenced by the Doppler effects and peak-to-average power ratio (PAPR), which are especially severe in the THz band. In this paper, a discrete Fourier transform spread orthogonal time frequency space (DFT-s-OTFS) system for THz ISAC is proposed with a two-stage sensing parameter estimation algorithm. The proposed sensing algorithm can realize millimeter-level range estimation accuracy and decimeter-per-second velocity estimation accuracy. Moreover, the proposed DFT-s-OTFS can improve the power amplifier efficiency by 10% on average compared to OTFS and enhance the sensing accuracy by one order of magnitude and the bit error rate performance by two orders of magnitude in high-mobility scenarios in contrast with orthogonal frequency division multiplexing (OFDM) and discrete Fourier transform spread OFDM (DFT-s-OFDM).