Underdetermined direction-of-departure and direction-of-arrival estimation in bistatic multiple-input multiple-output radar

•This paper proposes a subspace algorithm for underdetermined DOD and DOA estimation in MIMO radar., and its identifiability is analyzed.•A maximum likelihood solution, which is realized by alternating optimization, is also derived.

In this paper, target localization using bistatic multiple-input multiple-output radar where the source number exceeds the sizes of the transmit and receive arrays, denoted by M and N  , respectively, is addressed. We consider the Swerling II target in which the radar cross section varies in different pulses. Two algorithms for joint direction-of-departure (DOD) and direction-of-arrival (DOA) estimation of the targets are devised. The first one is a subspace-based estimator which is computationally simpler and can identify up to 2(M−1)(2N−1)2(M−1)(2N−1) sources, assuming that N≥MN≥M. The second is a maximum likelihood method with a higher estimation accuracy, where the DODs and DOAs are solved via alternating optimization. Simulation results are included to compare their mean square error performance with the Cramér–Rao lower bound.