NEW CLASS OF FOCUSSING MATRICES FOR COHERENT SIGNAL-SUBSPACE METHOD.

It is shown on the basis of theoretical and simulation results that the specific structure of the focusing matrix may have profound consequences in the statistical characteristics of the direction-of-arrival estimates. First, the focusing array signal-to-noise ratio (ASNR) loss and relative sufficiency measure are defined. Both can serve as performance measures for choosing a good focusing matrix. Next, factors that lead to the degradation of performance for the coherent-signal-subspace method based on the focusing matrices are identified. A new focusing matrix that is useful for general multigroup situations is introduced to provide a possible remedy. Various classes of focusing matrices are compared from the points of view of relative sufficiency of the reduced data and estimator/detector performance.