MULTIUSER VARIABLE-RATE SUBBAND CODING INCORPORATING DSI AND BUFFER CONTROL

This paper presents and analyzes a model of multiuser variable rate subband coding of speech incorporating digital speech interpolation (DSI). A dynamic bit assignment algorithm which minimizes the mean squared reconstruction error is presented. A backward estimation of subband variances is proposed which makes the bit assignment algorithm backward-adaptive and greatly reduces the need to send side information. A new switched-stepsize adaptation algorithm is used at the coders to improve system performance. With adaptive buffer control, buffer overflow is completely prevented. It has been shown by simulation means that a 2:1 DSI gain can be obtained with a relatively small buffer size.