Direction-of-arrival (DOA) estimation for wideband sources with array sensors is essential for source localization in radar, sonar and wireless sensor network. Wideband source whose bandwidth is larger compared with its center frequency is very common in the real world. In the past two decades, many methods have been proposed to resolve the DOA problem of wideband sources. Among these methods, incoherent subspace method (ISM) was proposed firstly. However, it cannot resolve coherent sources and performs worse at low signal noise ratio (SNR).

FENG Dahang, BAO Ming, GUAN Luyang, LI Xiaodong of Institute of Acoustics, Chinese Academy of Sciences carried out a series of studies and proposed a new method called focusing Khatri–Rao subspace (FKR) for wideband array processing.

FKR consists of two primary steps: (1) Focusing. (2) Arrangement. Compared with the conventional CSM that simply averages the covariance matrices of different frequency bins after focusing, FKR transforms the covariance matrices into a higher dimensional matrix through KR product. This method has three major advantages: (1) it achieves a higher resolution than CSM, (2) the root mean square error of DOA estimation from FKR is smaller than that of CSM when the initial angles are inaccurate and (3) it performs well even when the number of sensors is reduced to about half of the sources. The performance of the FKR method is demonstrated and analyzed through the computer simulations.

This research result was published on the recently issued Signal Processing (2011, 91(10):2415-2419)