Title :
Improving the speech quality of cellular mobile systems under heavy fading
Author :
Su, Huan-yu ; Mermelstein, Paul
Author_Institution :
BNR, Verdun, Que., Canada
Abstract :
Digital cellular systems experience heavy fading for short intervals during which the encoded bit stream may be severely corrupted. Requirements exist to detect the corrupted data slots and replace the corresponding information in the decoded speech stream by predicted speech based on previously corrected received data. The paper reports on error detection and speech regeneration techniques which achieve considerable quality improvements over those proposed for North American cellular use in IS-54, yet are compatible with it. Error detection is enhanced by setting a maximum likelihood threshold for Viterbi decoding and rejecting frames where the decoded sequence exceeds the threshold. Rejected frames are regenerated using the most recent correctly received speech coding parameters
Keywords :
cellular radio; digital radio systems; error detection; fading; speech coding; speech intelligibility; Viterbi decoding; cellular mobile systems; corrected received data; decoded speech stream; digital cellular systems; encoded bit stream; error detection; heavy fading; maximum likelihood threshold; predicted speech; speech coding parameters; speech quality; speech regeneration; Codecs; Convolutional codes; Cyclic redundancy check; Fading; Interleaved codes; Maximum likelihood decoding; Maximum likelihood detection; Protection; Speech coding; Viterbi algorithm;
Conference_Titel :
Acoustics, Speech, and Signal Processing, 1992. ICASSP-92., 1992 IEEE International Conference on
Conference_Location :
San Francisco, CA
Print_ISBN :
0-7803-0532-9
DOI :
10.1109/ICASSP.1992.226105
