A new missing ATM cell reconstruction scheme for ADPCM-coded speech

For adaptive differential pulse code modulation (ADPCM)-coded speech communications in asynchronous transfer mode (ATM) networks, it is very important to reduce the degradation of speech quality brought about by distortions causes by cell losses. The authors analyze the distortions brought about by applying conventional waveform substitution techniques to the missing ADPCM cell recovery. Based on this analysis, they propose a novel missing cell reconstruction technique, which, after making a pitch estimation from ADPCM codes, substitutes previously received ADPCM codes for the missing ones. This technique was implemented using a custom LSI processor, and it was confirmed that the speech quality degradation caused by cell loss was sufficiently reduced