Distributed closed-loop quasi-orthogonal space time block coding with four relay nodes: overcoming imperfect synchronization

In this paper, closed-loop quasi-orthogonal space time block coding (QO-STBC) is exploited within a four relay node transmission scheme to achieve full-rate and increase the available diversity gain provided by earlier two relay approaches. The problem of imperfect synchronization between relay nodes is overcome by applying a parallel interference cancellation (PIC) detection scheme at the destination node. Bit error rate simulations confirm the advantages of the proposed methodology for a range of levels of imperfect synchronization and that only a small number of iterations is necessary within the PIC detection