  The sixth generation (6G) wireless networks aim to achieve ultra-high data
transmission rates, very low latency and enhanced energy-efficiency. To this
end, terahertz (THz) band is one of the key enablers of 6G to meet such
requirements. The THz-band systems are also quickly merging as high-resolution
sensing devices because of their ultra-wide bandwidth and very narrow
beamwidth. As a means to efficiently utilize spectrum and thereby save cost and
power, THz integrated sensing and communications (ISAC) paradigm envisages a
single integrated hardware platform with common signaling mechanism. However,
ISAC at THz-band entails several design challenges such as beam split,
range-dependent bandwidth, near-field beamforming, and distinct channel model.
This article examines the technologies that have the potential to bring forth
ISAC and THz transmission together. In particular, it provides an overview of
antenna and array design, hybrid beamforming, integration with reflecting
surfaces and data-driven techniques such as machine learning. These systems
also provide research opportunities in developing novel methodologies for
channel estimation, near-field beam split, waveform design and beam
misalignment.

Signal Processing