  A new spatial IIR beamformer based direction-of-arrival (DoA) estimation
method is proposed in this paper. We propose a retransmission based spatial
feedback method for an array of transmit and receive antennas that improves the
performance parameters of a beamformer, viz. half-power beamwidth (HPBW),
side-lobe suppression, and directivity. Through quantitative comparison, we
show that our approach outperforms the previous feedback beamforming approach
with a single transmit antenna, and the conventional beamformer. We then
incorporate a retransmission based minimum variance distortionless response
(MVDR) beamformer with the feedback beamforming setup. We propose two
approaches, show that one approach is superior in terms of lower estimation
error, and use that as the DoA estimation method. We then compare this approach
with Multiple Signal Classification (MUSIC), Estimation of Parameters using
Rotation Invariant Technique (ESPRIT), robust MVDR, nested-array MVDR, and
reduced-dimension MVDR methods. The results show that at SNR levels of -60 dB
to -10 dB, the angle estiation error of the proposed method is 20 degree less
compared to that of prior methods.
