Transmit Subaperturing for MIMO Radars with Nested Arrays

We consider a multiple-input multiple-output (MIMO) radar equipped with a colocated nested array for both transmit and receive. A novel transmit subaperturing (TS) approach that decomposes the nested array into unequal subarrays is proposed to take the advantage of the degrees of freedom (DOF) provided by the nested array but without resorting to spatial smoothing. Phased-array and the conventional MIMO with omni-directional transmission (omni-MIMO) are also extended to the nested array scenario, which utilize spatial smoothing to improve their DOF. Simulation results show that with sufficient training data, the omni-MIMO with nested array achieves the highest output signal-to-interference-plus-noise ratio (SINR), while the TS-MIMO scheme outperforms the other methods when training is limited when the radar operates in a non-homogeneous environment.