Soft-bit assisted iterative AMR-WB source-decoding and turbo-detection of channel-coded differential space-time spreading using sphere packing modulation

Abstract

Jointly optimised iterative source- and channel-decoding is invoked for enhancing the error resilience of the Adaptive Multi Rate WideBand (AMR-WB) speech codec. The resultant AMR-WB coded speech signal is protected by Recursive Systematic Convolutional (RSC) codes and transmitted using a Sphere Packing (SP) aided Differential Space-Time Spreading-/(DSTS) assisted transceiver. The performance of the proposed scheme is evaluated when communicating over correlated non-dispersive Rayleigh fading channels. The proposed system exhibits an Eb/No gain of about 1 dB in comparison to the benchmark scheme carrying out joint channel decoding and DSTS aided SP-demodulation, but separate AMR-WB decoding, when using Iout = 4 external iterations. © 2007 IEEE.