Adaptive MIMO radar target parameter estimation with Kronecker-product structured interference covariance matrix

Multiple-Input Multiple-Output (MIMO) radar with colocated antennas has an increased target parameter estimation performance, but at the cost of increased computational complexity. This paper first presents the conditions required for the interference covariance matrix (ICM) of colocated MIMO radar to take a special structure, namely a Kronecker product of some sub-ICMs, and then proves that based on this ICM structure, the conventional Minimum Variance Distortionless Response (MVDR) algorithm can be reformulated into a combination of three estimation algorithms all of much smaller scales, such that the computational complexity is decreased significantly. However, this ICM structure can be destroyed by inactive scattering sources, whose influence is studied via numerical experiments. It is found that inactive point scatterers can still be suppressed by adaptive algorithms relying on the ICM structure, on condition that the number is fewer than that of receiving antennas.