Sphere-Packing Modulated Space-Time Coding Using Non-Binary LDPC-Coded Iterative-Detection

A recently proposed space-time block coding (STBC) signal construction method that combines orthogonal design with sphere packing, referred to here as (STBC-SP), has shown useful performance improvements over Alamouti´s conventional orthogonal design. In this contribution, we propose a purely symbol-based LDPC-coded scheme, demonstrating that the performance of STBC-SP systems can be further improved by concatenating sphere packing aided modulation with non-binary LDPC and by performing symbol-based turbo detection between the non-binary LDPC decoder and a rate-1 non-binary inner precoder. We also investigate the convergence behaviour of this symbol-based concatenated scheme with the aid of novel non-binary extrinsic information transfer (EXIT) charts. Finally, we demonstrate that in the investigated scenarios it requires 1-2 dB lower power in comparison to equivalent effective-throughput 0.5, 0.75 and 1 bit/symbol systems employing bit-based turbo detection.