A comparison between CELP and MPLPC at 8 kbit/s for mobile communications

Two analysis-by-synthesis schemes, with a different excitation structure, have been optimized for a bit-rate of 8 kb/s. The codebook excited linear predictive (CELP) coder and the multi-pulse linear predictive coder (MPLPC) were considered. Some improvements over conventional coders have been achieved by computing the long-term parameters by a closed-loop procedure and using a split vector quantization of line spectrum pair coefficients for the short-term spectrum representation. The complexity of the two schemes has been considered as a design constraint and the result is the implementation feasibility of both algorithms with standard floating-point digital signal processors. Both coders are shown to provide very high speech quality without transmission errors. The present study is pertinent to the development of the pan-European digital mobile radio system.<>