Research Issues, Challenges, and Opportunities of Wireless Power Transfer-Aided Full-Duplex Relay Systems

We present a comprehensive review for wireless power transfer (WPT)-aided full-duplex (1,D) relay systems. Two critical challenges in implementing WPT-aided Fll relay systems are presented, that is, pseudo Fll realization and high power consumption. Existing time-splitting or power-splitting structure based-WPT-aided Fll relay systems can only realize Fll operation in one of the time slots or only forward part of the received signal to the destination, belonging to pseudo Fll realization. Besides, self-interference is treated as noise and self-interference cancellation (SIC) operation incurs high power consumption at the FD relay node. To this end, a promising solution is outlined to address the two challenges, which realizes consecutive Fll realization at all times and forwards all the desired signal to the destination for decoding. Also, active SIC, that is, analog/digital cancellation, is not required by the proposed solution, which effectively reduces the circuit complexity and releases high power consumption at the Fll relay node. Specific classifications and performance metrics of WPT-aided Fll relay systems are summarized. Some future research is also envisaged for WPT-aided Fll systems.