New algorithms for suppression of narrowband interferences in DSSS communications

The paper proposes ways to judge whether narrowband interferences(NBIs) exist in DSSS system or not. Through judgment we further estimate the types of NBIs and then different algorithms in accordance with the types of interferences are employed. The existence of the NBI will cause the unevenness of the spectrum of the spread spectrum signal, thus using complex envelope in frequency domain can determine whether NBIs exist or not. In the paper, the nonlinear adaptive prediction and decision-directed Kalman filter are used to suppress the single tone and AR NBI respectively, whereas the multiuser detection algorithm is employed to suppress the digital NBI. The results show that methods proposed in the paper outperform over ones that use single method to suppress NBIs.