Wireless Power Transfer Based Adaptive Relaying With Energy Accumulation

Wireless power transfer (WPT) and cooperative relaying (CR) can promisingly sustain the operations of wireless nodes and improve the communication reliability. We design both orthogonal and non-orthogonal CR schemes with two sources communicating to two destinations with assistance from an energy harvesting relay. The WPT and CR are alternately and periodically performed. In the WPT phase, the relay can harvest energy from a power beacon. In the CR phase, two sources transmit their data to the relay, who can adaptively forward the source data according to its decoding status. When the relay cannot forward any data due to the decoding failures, a new WPT phase begins and the relay continues to harvest and accumulate energy. The energy status of the relay is properly modeled by defining a series of discrete levels. The average throughput is analyzed by considering various decoding and energy statuses of the relay. Numerical results reveal the impacts of key parameters to the system performance, such as the transmit powers of sources, the data transmission rates, and the relative distances between different terminals. It is shown that the non-orthogonal scheme performs much better than the orthogonal scheme for some system settings.