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.