Moment generating function-based pairwise error probability analysis of concatenated low density parity check codes with Alamouti coded multiple input multiple output-orthogonal frequency division multiplexing systems

Multiple input multiple output (MIMO) communication systems along with orthogonal frequency division multiplexing (OFDM) play a key role in designing next generation broadband wireless systems. Recently, low density parity check codes (LDPC) emerge as a good candidate for error correcting codes with capacity near Shannon´s limit. In this study, the authors derive moment generating function- based closed-form upper bounds on the pairwise error probability for serially concatenated LDPC codes with Alamouti coded MIMO-OFDM systems. Also bit error rate expressions are derived for the mentioned concatenation scheme under spatially independent and correlated quasi-static Rayleigh, Rician and Nakagami fading channels. The authors´ general framework considers the impact on coding and diversity gains because of spatial, time and frequency correlations, both individually and in combined form. In this study, the authors introduced the coexistence of spatial, time and frequency correlation channel models for proposed concatenation scheme and evaluate its effect on coding and diversity gain. Simulation results show that the proposed concatenation scheme is integrated in such a way that it takes advantage of every individual block. Further, the upper bounds derived in this study matches with the analytical results.