As digital speech transmission technology becomes more widespread, the trend is to find robust and low complexity bandwidth-efficient algorithms for speech coding. As forerunners in this area, the LPC based schemes like MPLPC [11 RPE , CELP , etc and recently, CELP-BB , have been extensively reported. With its reasonable complexity and high quality speech at low bit rates (2.4 to 4.8Kb/s)» CELP-BB is a good contender for 4.8Kb/s and below. Although all these schemes have good operation in ideal conditions, they cannot function properly under real channel conditions because of the less than ideal nature of most communication channels. In the past, the trend has been to find appropriate FEC schemes to protect the bits transmitted over given channels. However, for adequate protection large redundancy has to be used and so the original aim, speech transmission at low bit rates, is compromised. In an ideal system, the speech coder should have some error control capability while minimising delay, complexity and transmitted bit rate. In this paper we report on adaptation work done to give the CELP-BB coder just such a capability.
Bibliographic reference. Atungsiri, S. A. / Kondoz, A. M. / Evans, B. G. (1989): "A low bit rate speech coder optimized for forward error control", In EUROSPEECH-1989, 1314-1317.