Optimal Power Splitting in a Full-Duplex Wireless Powered Network with a Bidirectional Relay

This paper studies the optimal power splitting strategy in a full-duplex wireless powered communication network (WPCN). This wireless powered network contains three nodes, which are the access point (AP), the relay node (R) and the user. We divide the communication process into two phases that each one has the same duration time. The AP transmits the energy to the relay node and the user, and the user transmits the information to the relay node and the AP simultaneously in the first phase. In the second phase, R relays the energy to the user and simultaneously decodes the information and forwards the information signal to the AP. We study how R splits its harvested energy into two parts separately for energy harvesting (EH) and information forwarding, respectively, to maximize the achievable information rate from the user to the AP, when a direct link between AP and the user exists or does not. We get the mathematical results of optimal power splitting factor in two models. Numerical results show that the variation trend of the maximum achievable rate with the distance between the AP and R, and the rate with direct link is not always larger than the rate without direct link.