My observation is that for testing the performance of LMS algorithms always Gaussian white noise with zero mean is used as input signal (for both, the unknown and the adaptive system). Sometimes a cosine function of a certain frequency is added. In practice, however, the input signal is given by the application. The power density at f=0 could be much higher than at other frequencies. Standard adaptation algorithms seem to have difficulties to find the correct filter coefficients in such cases. Is there any special adaptation algorithm know for this problem?