Relay selection and power allocation for cognitive energy harvesting two-way relaying networks

Energy harvesting (EH) from ambient environment is an attractive and green solution to the problem of limited lifetime of wireless and mobile devices such as cognitive relay nodes. In this paper, we extend the previous works on cognitive two-way relaying network by introducing energy harvesting transceiver nodes that can accumulate energy to improve the lifetime of the relay network. We investigate an optimal offline joint relay selection and power allocation scheme where secondary transceivers and relays are energy harvesting nodes. We put forward an offline optimization problem of the maximization of the amplify-and-forward (AF) cooperative communication system throughput which can be solved by Lagrange function. Numerical results show that the proposed scheme performs better than random relay selection scheme on the restriction of transmit power and primary user (PU) interference.