Distributed turbo coded spatial modulation based on code matched interleaver for MIMO system

This paper investigates the turbo coded-spatial modulation (TC-SM) scheme based on code matched interleaver (CMI) for multiple input multiple output (MIMO) antenna system. The information bits for the selection of transmit active antenna and for the M-QAM modulated symbols are protected by a forward error correcting turbo code. In this work, we demonstrate that parallel encoding and decoding construction of the TC-SM scheme enabled us to effectively extend the TC-SM scheme to a turbo coded-cooperative spatial modulation (TCC-SM) scheme with CMI placed at the relay node. Numerical results based on Monte Carlo simulations revealed that the TCC-SM and TC-SM schemes outperform state of the art polar coded-cooperative spatial modulation (PCC-SM) and polar coded spatial modulation (PC-SM) schemes, respectively, under identical conditions. This performance improvement in bit-error rate (BER) of the proposed TCC-SM and TC-SM schemes occurred due to the joint soft input soft output log maximum a posteriori probability (SISO-Log-MAP) iterative decoding at the receiver. Furthermore, the mathematical error performance of the TC-SM scheme has also been presented. The numerical results demonstrate that the proposed TCC-SM scheme offers robustness not only in BER performance over the practical (non-ideal) source to relay channel but also presents less encoding and decoding complexity as compared to the PCC-SM scheme.