FPMIMO: A General MIMO Structure with Overlapping Subarrays for Various Radar Applications

Unlike the phased array (PA) radar that achieves array gain in proportion to the number of elements, the MIMO radar provides improvement to parameter estimation, target detection, and so on. Recently, the combination of the PA and MIMO concepts into the Phased MIMO (PMIMO) radar was proposed with overlapping non-coherent subarrays at the transmitter and an array with non-coherent elements at the receiver that proved to outperform the more conventional radars. This paper examines the parameter identifiability, i.e., the maximum number of detectable targets uniquely identified and the detection performance, i.e., the probabilities of detection and false alarm, of the Full PMIMO radar (FPMIMO), which is a further generalization of combination of the PA and MIMO concepts that uses overlapping subarrays on both transmit and receive arrays. The maximum number of resolvable targets on the FPMIMO radar is derived by the least squares (LS) method and its performance is subsequently evaluated numerically by considering the magnitude of target reflection coefficient as function of direction angle for comparison against PA, MIMO and PMIMO radars. Similarly, the derivation of expressions for probabilities of detection and false alarm is given. In particular, the numerical evaluation is made on the maximum number of resolvable targets with respect to the impact of the number of subarrays, the total number of elements and the element spacing, while the detection performance is evaluated based on the effect of threshold, SNR, and the number of subarrays. The results demonstrate that, being the more general form of multi-antenna radars, the FPMIMO radar is capable of flexibly trading off the maximum number and the lowest reflection coefficient of identifiable targets, with the PA, MIMO and PMIMO radars being special cases. The desired compromise can be obtained by adjusting the number of subarrays on the transmit and the receive arrays. An example of vehicular radar design that satisfies some mission requirements using the FPMIMO radar concept is also presented.