Narrow-band interference suppression in spread spectrum communication systems

Abstract In this paper the rejection of a narrow-band interference in DS (direct-sequence) spread spectrum communication systems by a digital filter is explored. A method for estimating the dominant frequency of the interference is presented. According to the estimated frequency the filter coefficients of a bandpass error filter are generated such that its centre frequency is at the estimated one. This error filter is realized by a recursive structure with only six multiplications and is approximately of zero phase. The interference is suppressed by compensating the non-filtered signal with the filtered one. A method to extract the characteristics of the different type of interferences is also presented in order to adjust the filter to make it suitable for their rejection. The performances of the filter in the environment of a white Gaussian noise and a narrow-band interference such as single-tone, swept-tone and narrow-band Gaussian interferences are simulated by computer, which shows that by using the given filter, the system performance can be greatly improved.

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