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-A recently proposed space-time 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 recent years, iterative decoding algorithms have attained substantial performance improvements in the context of wireless communication systems. In this paper, we demonstrate that the performance of STBC-SP systems can be further improved by concatenating sphere packing aided modulation with channel coding and performing demapping as well as channel decoding iteratively. The sphere packing demapper is modified for the sake of accepting a priori information that is obtained from the channel decoder. Bit-wise mutual information measures were also employed for the sake of searching for the optimum bits-to-symbol mapping. We present simulation results for the proposed scheme communicating over a correlated Rayleigh fading channel. At a BER of 10 −5 , the proposed turbo-detected STBC-SP scheme employing the optimum mapping was capable of achieving a coding gain of approximately 19dB over the identical-throughput 1 bit/symbol uncoded STBC-SP benchmarker scheme. The proposed scheme also achieved a coding gain of approximately 2dB over the 1 bit/symbol channelcoded STBC-SP benchmarker scheme that employed Gray mapping.

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