Wideband DOA estimation based on time-domain energy focusing

Wideband DOA estimation has become a significant concern in communication, navigation, and radar systems. Previous approaches employed the frequency-domain focusing method to alleviate the wideband impact, but it was constrained by its reliance on prior DOA knowledge. The time-domain wideband DOA estimation methods have also been explored, but often suffered from high-dimensional complexity. This work introduces a time-domain energy focusing (TDEF) scheme that leverages the known waveform and eliminates the reliance on prior DOA information and reduce the high-dimensional complexity. TDEF consists of multi-channel matched filtering and joint power-peak detection. The former concentrates signal energy in the time domain, while the latter mitigates peak migration induced by the wideband scenario. Through this process, the wideband scenario is transformed into an equivalent narrowband counterpart, enabling the application of narrowband DOA estimation techniques. Using matrix-perturbation analysis, we establish the theoretically asymptotic MSE equivalence between TDEF scheme and frequency-domain focusing. The numerical simulations show that the TDEF-based method achieves asymptotic performance approaching the CRLB without prior DOA information, improved resolution for closely spaced sources with different TOAs, and lower computational complexity, especially compared to time-domian sparsity-recovery methods.