Capacity of Relay Channels with Power Splitting and Dual Frequency Carriers

We consider a cooperative relay communication system where the source and the relay have separate frequency bands for message transmission. The relay is assumed to be a decode-forward node, i.e. It can decode the information send from the source node and re-transmit after suitable modifications. With power splitting at the source, we find an optimum relaying function which achieves the capacity of this relay network. The optimal power splitting algorithm is developed under two cases - one when the nodes have complete channel state knowledge and the other when nodes have limited information about the channel state. We extend the work to practical wireless systems and address the issue of message security.