System-compatible robustness improvement for new generation dect decoders by G.722 soft-decision decoding

The ITU-T Recommendation G.722 about subband adaptive differential pulse code modulation (SB-ADPCM) is the mandatory wideband speech codec in the new generation digital enhanced cordless telephony (NG-DECT). Although in ADPCM the difference signal instead of the original signal is quantized and adaptive prediction is employed, redundancy is yet observed within the quantized samples. In this paper we apply a soft-decision speech decoding technique which exploits this redundancy in terms of a priori knowledge and the channel reliability information to NG-DECT. In that way, we propose a novel scheme in a standard-compliant fashion which improves the robustness of the decoder. The performance of our proposal is evaluated in terms of speech quality and a noticeable improvement over the standard codec and its own packet loss concealment algorithm is observed.