Consistency of direction-of-arrival estimation with multipath and few snapshots

An analysis is made of the consistency of two direction-of-arrival estimation algorithms used in the presence of multipath propagation and with very few snapshots. The conditional maximum-likelihood (CML) algorithm and the method of direction estimation (MODE) are discussed. The cost functions of these algorithms are shown to coincide for a very large number of snapshots or very large signal-to-noise ratio. Necessary and sufficient conditions are derived for the algorithms to yield unique estimates. It is shown that their uniqueness conditions coincide with fundamental uniqueness conditions for the array that are independent of the algorithm used