Virtual Array for Dual Function MIMO Radar Communication Systems using OTFS Waveforms

A Multiple-Input Multiple-Output (MIMO) dual-function radar communication (DFRC) system transmitting orthogonal time frequency space (OTFS) waveforms is considered. A key advantage of MIMO radar is its ability to create a virtual array (VA), achieving higher sensing resolution than the physical receive array. In this paper, we propose a novel approach to construct a virtual array for the system under consideration. The transmit antennas can use the Doppler-delay (DD) domain bins in a shared fashion. A number of Time-Frequency (TF) bins, referred to as private bins, are exclusively assigned to specific transmit antennas. The TF signals received on the private bins are orthogonal and thus can be used to synthesize a virtual array, which, combined with coarse knowledge of radar parameters (i.e., angle, range, and velocity), enables high-resolution estimation of those parameters. The introduction of $N_{p}$ private bins necessitates a reduction in DD domain symbols, thereby reducing the data rate of each transmit antenna by $N_{p}-1$. However, even a small number of private bins is sufficient to achieve significant sensing gains with minimal communication rate loss.