Time-Frequency-Space Signal Design with Dynamic Subarray for Terahertz Integrated Sensing and Communication

Terahertz (THz) integrated sensing and communication (ISAC) enables simultaneous data transmission with Terabit-per-second (Tbps) rate and millimeter-level accurate sensing. To realize such a blueprint, ultra-massive antenna arrays with directional beamforming are used to compensate for severe path loss in the THz band. In this case, narrowbeam management with flexible beamforming is required to realize omnidirectional sensing. In this paper, the time-frequency-space signal design is investigated for THz ISAC to generate time-varying scanning sensing beams and stable communication beams. Specifically, based on a dynamic array-of-subarray hybrid beamforming architecture, two ISAC hybrid precoding algorithms are proposed, namely, a vectorization (VEC) based algorithm that outperforms existing ISAC hybrid precoding methods and a low-complexity sensing codebook assisted (SCA) approach. Numerical results indicate that the designed signal can realize centi-degree-level angle estimation accuracy, millimeter-level range estimation accuracy, and decimeter-per-second-level velocity estimation accuracy.