Soft-Bit Assisted Iterative AMR-WB Source-Decoding and Turbo-Detection of Channel-Coded Differential Space-Time Spreading Using Sphere Packing Modulation

摘要

Jointly optimised iterative source- and channel-decoding is used 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/N0 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 I = 4 external iterations.