Cooperative Relaying of Superposition Coding with Simple Feedback for Layered Source Transmission

We consider a relay network that delivers a Gaussian source by employing successive refinement source coding and superposition coding of layers at the source node and successive decoding at the relay and destination nodes. For the network, making use of the decoding results at the relay and destination nodes of the first transmission, an efficient relaying strategy of layers is proposed to minimize the expected distortion (ED) when only the average channel state information is available at the source node. Three types of the proposed scheme, defined as Prop-DF, using decode-and-forward signals, Prop-AF, using amplify-and-forward signals, and Prop-MF, using mixed-forward signals, are addressed and analyzed in terms of the outage probability and distortion exponent. Unlike other studies, we have also taken the relay location into account in deriving the distortion exponent showing the high SNR behavior of the ED. The results show that the proposed scheme increases the distortion exponent up to twice that of the conventional relaying schemes when the relay is close to the source node, and that Prop-MF provides the best performance for most relay locations.