  Joint communication and sensing (JCAS) technology has been regarded as one of
the innovations in the 6G network. With the channel modeling proposed by the
3rd Generation Partnership Project (3GPP) TR 38.901, this paper investigates
the sensing capability using the millimeter-wave (mmWave) band with an
orthogonal frequency division multiplexing (OFDM) waveform. Based on
micro-Doppler (MD) analysis, we present two case studies, i.e., fan speed
detection and human activity recognition, to demonstrate the target modeling
with micro-motions, backscattering signal construction, and MD signature
extraction using an OFDM waveform at 28 GHz. Simulated signatures demonstrate
distinct fan rotation or human motion, and waveform parameters that affect the
MD signature extraction are analyzed. Simulation results draw the validity of
the proposed modeling and simulation methods, which also aim to facilitate the
generation of data sets for various JCAS applications.
