A Selection-Based Cooperative SWIPT Scheme with Energy-Preserving DF Relays

This paper explores cooperative transmission in a simultaneous wireless information and power transfer (SWIPT) network with multiple energy-preserving decode-and-forward relays. We propose the optimal relay selection scheme to save energy and prolong network lifetime. To avoid decoding error propagation, a decoding set is constructed, which consists of the relays that can successfully decode the source signal through adjusting their power splitting ratios. Due to the insufficient energy or deep fading, some of the relays in decoding set may fail to deliver the source signal to destination. By excluding these relays from the decoding set, we further construct a forwarding set, from which one best relay is then selected to forward the information-bearing signal, while all the unselected relays keep on harvesting energy for future use. The relay selection criterion is the maximal remaining energy of the relays, so as to prolong network lifetime. Simulation results demonstrate that the proposed scheme provides longer lifetime as compared to the conventional ones.