  Enabled by the advancement in radio frequency technologies, the convergence
of radar and communication systems becomes increasingly promising and is
envisioned as a key feature of future 6G networks. Recently, the
frequency-hopping (FH) MIMO radar is introduced to underlay dual-function
radar-communication (DFRC) systems. Superior to many previous radar-centric
DFRC designs, the symbol rate of FH-MIMO radar-based DFRC (FH-MIMO DFRC) can
exceed the radar pulse repetition frequency. However, many practical issues,
particularly those regarding effective data communications, are
unexplored/unsolved. To promote the awareness and general understanding of the
novel DFRC, this article is devoted to providing a timely introduction of
FH-MIMO DFRC. We comprehensively review many essential aspects of the novel
DFRC: channel/signal models, signaling strategies, modulation/demodulation
processing and channel estimation methods, to name a few. We also highlight
major remaining issues in FH-MIMO DFRC and suggest potential solutions to shed
light on future research works.
