Performance analysis of underlay two-way relay cooperation in cognitive radio networks with energy harvesting

Cognitive radio and energy harvesting are two important approaches to solve the problem of spectrum scarcity and energy constraint in wireless communications. In this work, we study a two-way relay cooperation scheme in underlay cognitive radio networks (CRNs) with energy harvesting in which two secondary users exchange information via an energy harvesting relay node. Since the relay node collects energy from the received signals and utilizes it to forward the information, the secondary transmission power can be markedly reduced. Therefore the interference of the secondary network to the primary network can be substantially reduced. We derive the outage probability of the secondary network and analyze the ergodic sum-rate of the secondary network. For the relay selection scheme, we find the optimal relay by employing interior point method based on a penalty function. Numerical results show that the proposed scheme gives higher throughput for the secondary network than other strategies.