Hierarchical MUSIC Technique for Direction Finding of Multiple Signal Sources

We propose a novel hierarchical multiple signal classification (H-MUSIC) technique that elaborately estimates the direction-of-arrival (DOA) of multiple signal sources arriving from similar directions. In general, the conventional MUSIC technique does not result in a good DOA estimation performance in this case. The basic idea of the proposed H-MUSIC technique is to combine the conventional MUSIC and beam-space MUSIC techniques. The receiver performs a coarse DOA estimation using the conventional MUSIC technique as a first step, considering a whole range of directions. Then, in the subsequent step, the receiver additionally performs a fine DOA estimation using the beam-space MUSIC technique, focusing on the directions where the signals are likely to exist. Through extensive computer simulations, we show that the proposed H-MUSIC technique significantly outperforms the conventional MUSIC technique even in the low signal-to-noise (SNR) regions and with a small number of time samples.