Time-Switching Based In-Band Full Duplex Wireless Powered Two-Way Relay

In this paper, we study wireless powered two-way amplify-and-forward (AF) relay, where an energy-constrained relay assists information transmission between the hybrid access point (H-AP) and the cell-edge node by using the harvested energy from both the H-AP signal and the loop-back signal at the relay. Since conventional half duplex two-way relay scheme can either harvest energy or transmit information, we propose a new two-way AF relaying protocol which operates in full duplex mode with simultaneous energy harvesting and information transmission. The relay not only harvests energy from the dedicated energy signal from the H-AP but also recycles its own transmitted signal, which is termed self-energy recycling. The proposed protocol also addresses the issue of in-band self-interference at the H-AP caused by the full duplex operation in two-way relay. The sum throughput optimization problem is formulated under the relay energy constraint, where time-switching parameter is optimized. Numerical results show significant sum-throughput performance gain achieved by the proposed protocol over the existing one.