On the Joint Adaptation of Memory-Based Nonlinear Adaptive Filters Used in Echo Cancellation

  • Daniel Mueller
  • August Kaelin
Conference paper


Echo cancellation is one of the key challenges in modern full-duplex digital data transmission systems. To achieve the necessary echo loss, not only a large amount of computing power is required but also highly linear data converters. In this paper, we present a concept which reduces the dynamic range of the A/D converter in the receive path by substracting a coarse analog echo estimate from the received signal. Such a coarse estimate is built with the help of the most significant bits of a conventional digital adaptive echo canceler (AEC) and a low-cost D/A converter. To compensate for its nonlinearities, a memory-based nonlinear adaptive filter (MBAF) is used. Unfortunately, this MBAF interferes with the AEC. Using simplified models of both adaptive filters, it is possible to analyze the joint adaptation behaviour. It is shown that the joint adaptation of two adaptive filters is stable in a real system such as an HDSL modem. It adapts very slowly but is still capable of tracking small variations of the system.


Minimum Mean Square Error Adaptive Filter Error Surface Error Power Adaptive Gain 
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Copyright information

© Springer-Verlag London Limited 1998

Authors and Affiliations

  • Daniel Mueller
    • 1
  • August Kaelin
    • 2
  1. 1.Philips Semiconductors AGZürichSwitzerland
  2. 2.Signal and Information Processing LaboratoryETH ZürichZürichSwitzerland

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