MODE with extra-roots (MODEX): a new DOA estimation algorithm with an improved threshold performance

We propose a new MODE-based direction of arrival (DOA) estimation algorithm with an improved SNR threshold as compared to the conventional MODE technique. Our algorithm preserves all good properties of MODE, such as asymptotic efficiency, excellent performance in scenarios with coherent sources, as well as a reasonable computational cost. Similarly to root-MODE, the proposed method does not require any global multidimensional optimization since it is based on a combination of polynomial rooting and a simple combinatorial search. Our technique is referred to as MODEX (MODE with EXtra roots) because it makes use of a certain polynomial with a larger degree than that of the conventional MODE-polynomial. The source DOAs are estimated via checking a certain (enlarged) number of candidate DOAs using either the stochastic or the deterministic maximum likelihood function. To reduce the computational cost of MODEX, a priori information about source localization sectors can be exploited.