  Motivated by future automotive applications, we study some joint radar target
detection and parameter estimation problems where the transmitter, equipped
with a mono-static MIMO radar, wishes to detect multiple targets and then
estimate their respective parameters, while simultaneously communicating
information data using orthogonal time frequency space (OTFS) modulation.
Assuming that the number of radio frequency chains is smaller than the number
of antennas over the mmWave frequency band, we design hybrid digital-analog
beamforming at the radar transmitter adapted to different operating phases. The
first scenario considers a wide angular beam in order to perform the target
detection and parameter estimation, while multicasting a common message to all
possible active users. The second scenario considers narrow angular beams to
send information streams individually to the already detected users and
simultaneously keep tracking of their respective parameters. Under this setup,
we propose an efficient maximum likelihood scheme combined with hybrid
beamforming to jointly perform target detection and parameter estimation. Our
numerical results demonstrate that the proposed algorithm is able to reliably
detect multiple targets with a sufficient number of antennas and achieves the
Cram\'er-Rao lower bound for radar parameter estimation such as delay, Doppler
and angle-of-arrival (AoA).
