Energy-Aware Relay Selections for Simultaneous Wireless Information and Power Transfer

In this paper, an amplify-and-forward (AF) based wireless relay network is considered, where the energy constrained relay nodes utilize both the energy harvested from the source's RF signals and energy stored in the battery to forward information to the destination. To consume the energy in the battery as less as possible, the method to derive the smallest extra energy from the battery through adjusting the power ratio is presented. Furthermore, to extend the lifetime of the wireless network, three energy-aware distributed relay selection strategies, Maximum Residual Energy (MRE) strategy, Minimum Extra Energy (MEE) strategy and Minimum Extra Energy-efficiency Index (MEEI) strategy are also proposed. Via simulations, it is demonstrated that the MEEI strategy outperforms MEE strategy and MRE strategy with greater throughput and longer lifetime.