On secure communication over a class of degraded relay networks

In this paper we consider a class of degraded relay networks with multiple receivers, address the capacity region for the multicast case, and consider information-theoretic security aspects. Exemplary, we study a degraded relay network, which is comprised of one source, an arbitrary number of relay nodes, and two receiver nodes in a degraded setting. Based on a simple combination of superposition encoding and decode-and-forward at the relay nodes we provide an achievable rate region for this network. We then consider a related setup where the weaker receiver node now plays the role of an eavesdropper who is able to listen to the transmission of the source and all relays in the network. Based on the result for the degraded relay network case we then provide an achievable secrecy rate for this setup.