  A novel dual-function radar communication (DFRC) system is proposed, that
achieves high target resolution and high communication rate. It consists of a
multiple-input multiple-output (MIMO) radar, where only a small number of
antennas are active in each channel use. The probing waveforms are orthogonal
frequency division multiplexing (OFDM) type. The OFDM carriers are divided into
two groups, one that is used by the active antennas in a shared fashion, and
another one, where each subcarrier is assigned to an active antenna in an
exclusive fashion (private subcarriers). Target estimation is carried out based
on the received and transmitted symbols. The system communicates information
via the transmitted OFDM data symbols and the pattern of active antennas in a
generalized spatial modulation (GSM) fashion. A multi-antenna communication
receiver can identify the indices of active antennas via sparse signal recovery
methods. The use of shared subcarriers enables high communication rate. The
private subcarriers are used to synthesize a virtual array for high angular
resolution, and also for improved estimation on the active antenna indices. The
OFDM waveforms allow the communication receiver to easily mitigate the effect
of frequency selective fading, while the use of a sparse array at the
transmitter reduces the hardware cost of the system. The radar performance of
the proposed DFRC system is evaluated via simulations, and bit error rate (BER)
results for the communication system are provided.
