On the imperfection of channel estimation, relay's forwarding policy and destination's knowledge of signal presence
In this paper, we analyze two different decode-and-forward (DF) relay-assisted communication system models, which display different levels of practicality and represent large classes of DF systems in the literature. We spell out delineating aspects of the two models and rigorously show inequality among their symbol error probabilities (SEPs). Both system models assume imperfect channel side information at receivers and maximum ratio combining (MRC) at the destination node.