Bidirectional wireless information and power transfer for decode-and-forward relay systems

In this study, the authors investigate the bidirectional wireless information and power transfer (BWIPT) in decode-and-forward (DF) relay systems, where the bidirectional relay can decode and forward information from the user to the access point (AP), and assist the wireless power transfer from the AP to the user. The relay employs the power splitting (PS) protocol to coordinate the received signal energy for information transmission and energy harvesting. By converting the multi-relay system information rate maximisation problem into a convex optimisation problem, the distributed power allocation scheme is obtained to maximise the information rate. Particularly, for single-relay systems, the authors derive the closed-form expression of the optimal PS factor, which can maximise the information rate. Simulation results show that the BWIPT for DF relay systems outperforms the BWIPT for amplify-and-forward relay systems.