The Achievable Distortion of Relay-Assisted Block Fading Channels

This letter concerns the achievable distortion of a Gaussian source over a relay-assisted block fading channel under mean square-error distortion measure. It is assumed the communication is occurred in two hops through the use of a relay node, where the Decode and Forward (DF) strategy is employed at this node. Also, the transmitter does not have the channel state information, while the channel gains associated with both hops are available at the relay. It is assumed the Gaussian source is hierarchically encoded through using scalable source coding approach, and is sent to the DF relay through the use of a multi-layer code, while the relay sends the retrieved information through a single layer code. In this regard, in a Rayleigh block fading environment, the optimal power allocation strategy across code layers is derived, showing the resulting distortion outperforms that of using AF relaying or exploiting a single layer code.