Distributed turbo coding with selective relaying

In this paper, we consider a general two-hop relay network and propose a distributed turbo coding with selective relaying (DTC-SR) scheme to improve the performance of relayed transmission. In the proposed scheme, each relay adaptively selects an amplify and forward (AAF) or a decode and forward (DAF) protocol based on whether it can decode correctly or not. Among all the relays, a single relay, which has the maximum destination SNR, is selected for transmission. If the selected relay uses the DAF protocol, it decodes the received signals, interleaves, re-encodes and forwards them to the destination. At the destination, the signals directly transmitted from the source and that from the selected relay form a distributed turbo code (DTC). If the selected relay uses the AAF protocol, it just simply amplifies the received signal. The destination then combines the signals transmitted from the source and the relay. Simulation results show that the DTC-SR can take advantages of both distributed turbo coding and relay selection, providing not only a considerable SNR gain contributed from the relay selection, but also a coding gain contributed from the distributed turbo coding. And these gains increase as the number of relay increases.