Source-assisting strategy for distributed space-time block codes

Most of the previous works on distributed space-time coding assume that there is no direct link between the source and the destination, which means that the source is not actively involved in cooperation. In order to present the benefits that can be extracted when the source is actively involved in cooperation, we propose a source-assisting (SA) strategy for distributed orthogonal and quasi-orthogonal space-time block coded cooperative multi-hop networks. We adopt a two time-slot protocol using the decode-and-forward model, where in the first time slot, the source transmits while the relay and destination nodes all receive, and in the second time slot, the source and relay nodes transmit and the destination node receives. Numerical and simulation results show that our SA strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs, at the expense of slightly increased complexity of the ML detector. An explanation on the modified structure of the ML detector is provided.