Terahertz-Band Integrated Sensing and Communications: Challenges and Opportunities

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 emerging 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.