Optimal scheduling and power allocation for wireless powered two-way relaying systems

We consider a two-way wireless powered cooperative system where the relay not only helps to forward the information for the user nodes, but also acts as an energy beacon. Assuming that due to the hardware limitation, harvesting energy and information transmission cannot be performed simultaneously, we propose a novel three-phase energy harvesting and transmission protocol. In the first phase, the relay broadcasts radio frequency (RF) energy signals which is harvested by both user nodes. In the second and third phase, the user nodes communicate with each other via the relay node. Thus, in order to maximize the network throughput, it is critical to investigate the tradeoff between the durations of the wireless energy harvesting phase and the information transfer phases. In particular, we maximize the throughput for the proposed wireless powered two-way relaying systems by jointly optimizing the durations of wireless energy harvesting and information transmission phases, and the power allocation for transmissions. The optimal solution is obtained, and through simulations, we show the effectiveness of the proposed scheme as compared to the benchmark schemes.