Dual-hop Amplify-and-Forward Transmission With Imperfect Channel Estimates at the Relay

With reference to the typical three-node Amplify-and-Forward (AF) relaying setup, where a single relay assists the communication between a source terminal and a destination terminal, the authors investigate the effect of outdated Channel State Information (CSI) at the relay on the overall performance. In particular, they consider CSI-assisted (i.e., variable-gain) AF relaying and derive expressions for the outage and the error probability for the case where the relay gain is adapted based on outdated estimates of the source-relay channel, when operating over Nakagami-m fading.