A purely symbol-based precoded and LDPC-coded iterative-detection assisted sphere-packing modulated space-time coding scheme

In this contribution, we propose a purely symbol-based LDPC-coded scheme based on a space-time block coding (STBC) signal construction method that combines orthogonal design with sphere packing, referred to here as (STBC-SP). We demonstrate that useful performance improvements may be attained when sphere packing aided modulation is concatenated with non-binary LDPC especially, when performing purely symbol-based turbo detection by exchanging extrinsic information 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. The proposed symbol-based turbo-detected STBC-SP scheme exhibits a 'turbo-cliff' at E_b/N₀ = 5.0 dB and achieves an E_b/N₀ gain of 19.2 dB at a BER of 10 ^-5 over Alamouti's scheme