Source-dependent channel coding for CELP

Source-dependent channel-error codes for speech compression algorithms are obtained by minimizing an appropriate speech distortion criterion under channel-error conditions. A simulated annealing algorithm for optimizing such a criterion is described. The resulting channel codes are efficient since they provide error correction of nonuniform accuracy (highly probable quantization levels receive more accurate correction) and/or nonuniform error detection (serious errors are more likely to be detected). An optimal tradeoff between error correction and error detection (associated with a recovery procedure) is obtained. Any desired fraction of the codewords can be allocated for error protection, including noninteger bit allocations. The performance of the source-dependent channel-coding technique is reported for the code-excited linear prediction (CELP) algorithm