Abstract: A decoder in a communication system using channel optimized vector quantization and including an encoder stores active encoder centroids ci corresponding to active indices i, an active index being defined as an index that has a predetermined source probability pi>0 of being selected by the encoder for transmission to the decoder, source probabilities pi and the bit error rate epsilon to dynamically estimate a decoded vector using a sub-optimal algorithm in which only the most significant contributions are considered.

Abstract: A decoder improves delayed packet concealment in a packet network by using two decoder sections. A first decoder section bases its decoding during the concealment phase on erroneous filter states and a set of speech parameters, whereas a second decoder section bases its decoding on saved and updated filter states and the same speech parameters. The outputs of the two decoder sections are thereafter combined to form the final speech signal. This decoding strategy produces a speech signal with smooth transitions from delayed to non-delayed packets and uses information from the most recent packets for speech generation.