  The Terahertz (0.1-10 THz) band holds enormous potential for supporting
unprecedented data rates and millimeter-level accurate sensing thanks to its
ultra-broad bandwidth. Terahertz integrated sensing and communication (ISAC) is
viewed as a game-changing technology to realize connected intelligence in 6G
and beyond systems. In this article, challenges from THz channel and
transceiver perspectives, as well as difficulties of ISAC are elaborated.
Motivated by these challenges, THz ISAC channels are studied in terms of
channel types, measurement and models. Moreover, four key signal processing
techniques to unleash the full potential of THz ISAC are investigated, namely,
waveform design, receiver processing, narrowbeam management, and localization.
Quantitative studies demonstrate the benefits and performance of the
state-of-the-art signal processing methods. Finally, open problems and
potential solutions are discussed.
