A 5.85 kbits CELP algorithm for cellular applications

Two versions of the RCELP (relaxation-type code excited linear prediction) algorithm are described. They show that the generalized analysis-by-synthesis paradigm provides increased coding efficiency in practical applications, and that it can be implemented in a variety of ways. A novel pitch-period extraction algorithm which improves the effectiveness of RCELP is described. The computational requirements of RCELP are similar to or less that those of an equivalent conventional CELP algorithm. Existing fast procedures for the fixed-codebook contribution to the excitation can be used. At 5.85 kbit/s the two versions of RCELP provide a speech quality which is equal to the current 13 kbit/s GSM speech-coding standard. It is shown that only using the perceptual weighting where needed results in reduction of computational effort and can increase speech quality.<>