Residual error rate in single-relay dual-hop systems with retransmission

In this paper, we investigate the residual error rate in decode-and-forward (DF) relaying systems with retransmission. We assume the single-relay dual-hop systems with Rayleigh fading channels that include the path loss effects. If we assume that the number of used orthogonal time slots is equal to the number of allowed retransmission, the diversity paths are accumulated at relay and destination. Thus, we analyze the residual errors according to existence of diversity paths. Specially, we focus on two policies: selecting the best node to transmit at every phase (SB) and selecting the source node as the transmitter at every other phase (SS), i.e., the source transmits at every odd time slot. In addition, for each policy, we consider two types of channel assumption: static and non-static channels during the whole retransmission period, respectively. Numerical results confirm that the residual error rate with diversity paths and non-static assumption is lower than without one. Also, we find that the SB protocol outperforms in terms of the residual error.