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We propose a two-stage adaptive filtering process
for canceling narrowband interference from a wideband
signal process, based on a reference signal consisting
of a Doppler shifted version of the interference. The
first stage uses the time-varying behavior of NLMS with
large step-size to produce an estimate of the interference
signal, in which the Doppler shift is mitigated. The
second stage uses NLMS with small step-size, as an approximation
to the Wiener filter, in order to modify amplitude and
phase of the Doppler-mitigated reference signal so that
an estimate of the interference signal is produced suitable
for interference cancellation. Simulations with a wideband
QPSK signal corrupted by strong sinusoidal interference,
for which a Doppler shifted reference is available,
show the performance of the proposed approach in terms
of signal-to-interference ratio and bit-error rate improvement.
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