Combined adaptive beamforming schemes for nonstationary interfering noise reduction

• This paper introduces adaptive beamforming methods reducing nonstationary interfering signals.
• The trademark of the proposed methods lies in the combined adaptive noise canceller (ANC) system.
• Two different way of combining ANC systems are presented.
• A further combined architecture is introduced based on a multi-stage combination of ANC systems.
• The effectiveness of the proposed schemes is assessed in the presence of nonstationary interferences.

This paper introduces new adaptive beamforming methods for nonstationary noise reduction, designed to be robust against broadband interfering signals. In particular, we propose combined beamforming schemes within a standard adaptive beamforming system, such as the generalized sidelobe canceller (GSC). The novelty of such combined adaptive beamformers relies on the use of different adaptive sidelobe cancelling structures which allow the system to achieve robustness in nonstationary noisy environments. The combined structures are based on the convex combination of two multiple-input single-output (MISO) adaptive systems with complementary capabilities. The whole beamformer benefits from such combination and results to be able to preserve the best properties of each system. We introduce two different adaptive schemes, whose difference lies in the way of combining the MISO systems. Moreover, we present a further adaptive beamforming scheme which generalizes the previous techniques, thus improving the robustness against nonstationary interfering signals in multisource environments. The effectiveness of the proposed systems is also assessed in a nonstationary dense multipath environment. The experiments show that the proposed combined beamforming schemes are capable of enhancing the desired signal even in the presence of nonstationary interfering signals.