Improved amr wideband error concealment for mobile communications

Mobile wideband speech communication (HD Voice) is more and more available in the past years, primarily in 3G networks. The specifics of mobile communication - even if it is packet-switched - is that received frames with residual bit errors after channel decoding must not necessarily be marked as lost, instead they may be marked as bad (bad frame indicator, BFI). In this work we present how to exploit the information of a soft input (i. e., a log-likelihood ratio input) within the Adaptive Multirate Wideband (AMR-WB) speech decoder, allowing a more robust error concealment as compared to the 3GPP Recommendation. Log-likelihood ratios may be taken from a soft-output channel decoder, or, as in our generic simulation, directly from the demodulator, without the need of a BFI. Since error concealment is non-mandatory, chipset manufacturers are free to implement this alternative speech decoding scheme still in a standard-compliant fashion.