The role of subspace swap in music performance breakdown

Direction-of-arrival estimation performance of MUSIC in the so- called "threshold" area is often attributed to the "subspace swap" phenomena. We show that the subspace swap condition can be accurately predicted using recent results from Random Matrix Theory (RMT) analysis, but that subspace "leakage" rather than full sub- space swap is associated with the onset of performance degradation in closely spaced multiple source scenarios. Prediction of the "sub- space swap" phenomena is examined analytically and by the use of Monte-Carlo simulation.