On the feasibility of full-duplex relaying powered by wireless energy transfer

We consider a wireless two-hop downlink communication system where a grid-connected source node transmits data to a destination node with the assistance of a full-duplex (FD) relay that is powered by wireless energy harvesting. The relay splits its received signal from the first hop into two streams for energy harvesting and information decoding, respectively. Meanwhile, it also forwards the decoded information to the second hop utilizing a portion of the harvested energy. To maximize the data rate, the power splitting factor and energy consumption proportion are jointly optimized in the case of single-antenna transceivers. The analytical results are then used for studying the feasibility of full-duplex relaying and wireless energy transfer. As for the main conclusions, we note that so-called self-energy recycling gives marginal gain for the considered system and relaying at large is useful only when the direct source-to-destination link is very weak. The latter aspect is pronounced in the considered system especially due to the presence of residual full-duplex self-interference and the fact that the relay is powered by an extremely scarce source, i.e., wireless energy transfer.