Multiuser rate subband coding incorporating DSI and buffer control

A model of multiuser variable rate subband coding of speech incorporating digital speech interpolation (DSI) is presented and analyzed. A dynamic bit assignment algorithm which minimizes the mean squared reconstruction error is presented. A backward estimation of subband variances which makes the bit assignment algorithm backward-adaptive and greatly reduces the need to send side information is proposed. A novel 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