Stochastic joint source-channel coding for low bit rate robust speech coding
Merouane Bouzid, Hichem Benkherouf, Khaled Benzadi · 2011
Speech coders operating at low bit rates necessitate efficient encoding of the linear predictive coding (LPC) coefficients. In this paper, we propose a stochastic joint source-channel scheme developed for efficient and robust encoding of LPC coefficients in terms of LSF parameters. The encoding system, named LSF-SSCOVQ-RC, is an LSF encoding scheme based on a reduced complexity stochastic split vector quantizer optimized for noisy channel. For transmissions over noisy channel, we will show first that our LSF-SSCOVQ-RC encoder outperforms the conventional LSF encoder designed by the split vector quantizer (SVQ). After that, we applied the LSF-SSCOVQ-RC encoder (with weighted distance) for the robust encoding of LSF parameters of the MELP speech coder operating over a noisy channel. The simulation results will show that the proposed LSF encoder, incorporated in the MELP, ensure better performances than the original MELP MSVQ of 25 bits/frame; especially when the channel is highly disturbed.