An Efficient Narrowband Null-Steering Beamformer for Interference Mitigation in Wireless Communications

In wireless communication systems, it is frequently preferable to use a null steering beamformer to reduce interference from strong narrowband signals and other multi-path signals. This paper proposes an efficient narrowband null-steering beamformer based on an Improved Davies Narrowband Null-steering (IDNN) algorithm combined with an Improved Constant Modulus Algorithm (ICMA). The designed beamformer can impose adaptive nulls at interferences without knowing directions in the side lobe region by employing the ICMA for signal adaptation, while maintaining the main lobe toward the desired user direction. The results reveal that the developed beamformer increased the convergence rate by 12.8%, as seen by lower output power convergence when compared to the traditional Davies Narrowband Null-steering (DNN) algorithm. Thus, the new algorithm is observed to have much faster convergence behavior.