Non-Wiener Phenomenon in Oversampled Subband Adaptive Filters

Traditionally held beliefs assert that the minimum mean-square error (MMSE) of subband adaptive filters is higher than that of the equivalent fullband filter. In this paper we show that this is not always the case. Oversampled subband adaptive filters with white and speech-like excitation are observed to produce MMSE levels well below those of the equivalent fullband filter and even below the linear and time-invariant (LTI) Wiener filter. This observation is attributed to non-Wiener behavior, which has previously been observed in adaptive filters with narrowband inputs.