Patent ID: 6728319
Filing Date: 2004-04-27
Classification: H03M

Abstract:
A decoding method in a communication system using channel optimized vector quantization and including an encoder and a decoder, characterized by performing the following steps at said decoder:storing 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 said encoder for transmission to said decoder over a transmission channel; storing said source probabilities pi; storing a transmission channel quality measure; dynamically calculating, from said stored transmission channel quality measure, a set of conditional channel transition probabilities pj|i that an index j has been received by said decoder given that an index i has been sent by said encoder; calculating an estimate &ccirc;j of a decoded vector in accordance with the formula. c^j=&Sum;activeindicesiâ€ƒ&it;â€ƒ&it;ci&CenterDot;pj|i&CenterDot;pi&Sum;activeindicesiâ€ƒ&it;â€ƒ&it;pj|i&CenterDot;piwhere the summations are restricted to only the most significant terms, and the terms are summed in descending conditional channel transition probability order; andstopping summation at the latest when a predetermined number L, which is less than the number of active indices, of terms have been summed.