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 paper, the time-frequency-space transmit design is investigated for THz ISAC to generate time-varying scanning sensing beams and stable communication beams. Specifically, with the dynamic array-of-subarray (DAoSA) hybrid beamforming architecture and multi-carrier modulation, 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. Meanwhile, coupled with the transmit design, parameter estimation algorithms are proposed to realize high-accuracy sensing, including a wideband DAoSA MUSIC (W-DAoSA-MUSIC) method for angle estimation and a sum-DFT-GSS (S-DFT-GSS) approach for range and velocity estimation. Numerical results indicate that the proposed algorithms can realize centi-degree-level angle estimation accuracy and millimeter-level range estimation accuracy, which are one or two orders of magnitudes better than the methods in the millimeter-wave band. In addition, to overcome the cyclic prefix limitation and Doppler effects in the THz band, an inter-symbol interference- and inter-carrier interference-tackled sensing algorithm is developed to refine sensing capabilities for THz ISAC.

翻译：太赫兹(THz)集成感知与通信(ISAC)能够实现每秒太比特(Tbps)级数据传输与毫米级精确感知同步进行。为实现这一蓝图，采用超大规模天线阵列结合定向波束成形来补偿太赫兹频段的严重路径损耗。本文针对太赫兹ISAC系统研究了时频空发射设计方法，以生成时变扫描感知波束与稳定通信波束。具体而言，基于动态子阵列组(DAoSA)混合波束成形架构和多载波调制技术，提出了两种ISAC混合预编码算法：性能优于现有ISAC混合预编码方法的基于向量化(VEC)算法，以及低复杂度感知码本辅助(SCA)方法。同时，结合发射设计提出了实现高精度感知的参数估计算法，包括用于角度估计的宽带DAoSA多信号分类(W-DAoSA-MUSIC)方法，以及用于距离和速度估计的和-离散傅里叶变换-高斯和搜索(S-DFT-GSS)方法。数值结果表明，所提算法可实现百分之一度级的角度估计精度和毫米级的距离估计精度，比毫米波频段方法优化一至两个数量级。此外，为克服太赫兹频段循环前缀限制与多普勒效应，还开发了抗符号间干扰和载波间干扰的感知算法，以提升太赫兹ISAC系统的感知能力。