Channel Codes That Exploit the Residual Redundancy in CELP- Encoded Speech

dc.contributor.authorAlajaji, Fadyen_US
dc.contributor.authorPhamdo, N.en_US
dc.contributor.authorFuja, Tom E.en_US
dc.description.abstractWe consider the problem of reliably transmitting CELP-encoded speech over noisy communication channels. Our objective is to design efficient coding/decoding schemes for the transmission of the CELP line spectral parameters (LSP's) over very noisy channels.<P>We begin by quantifying the amount of ﲲesidual redundancy inherent in the LSP's of Federal Standard 1016 CELP. This is done by modeling the LSP's as first and second-order Markov chains. Two models for LSP generation are proposed; the first model characterizes the intra-frame correlation exhibited by the LSP's, while the second model captures both intra-frame and inter-frame correlation. By comparing the entropy rates of the models thus constructed with the CELP rates, it is shown that as many as one-third of the LSP bits in every frame of speech are redundant.<P>We next consider methods by which this residual redundancy can be exploited by an appropriately designed channel decoder. Before transmission, the LSP's are encoded with a forward error control (FEC) code; we consider both block (Reed- Solomon) codes and convolutional codes. Soft-decision decoders that exploit the residual redundancy in the LSP's are implemented assuming additive white Gaussian noise (AWGN) and independent Rayleigh fading environments. Simulation results employing binary phaseshift keying (BPSK) indicate coding gains of 2 to 5 dB over soft-decision decoders that do not exploit the residual redundancy.en_US
dc.format.extent1133655 bytes
dc.relation.ispartofseriesISR; TR 1996-43en_US
dc.subjectdata compressionen_US
dc.subjectdigital communicationsen_US
dc.subjecterror-detection codesen_US
dc.subjectinformation theoryen_US
dc.subjectrobust information processingen_US
dc.subjectsignal processingen_US
dc.subjectspeech processingen_US
dc.subjectIntelligent Signal Processing en_US
dc.subjectCommunications Systemsen_US
dc.titleChannel Codes That Exploit the Residual Redundancy in CELP- Encoded Speechen_US
dc.typeTechnical Reporten_US


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