  Wireless energy harvesting (WEH) has been recognized as a promising technique
to prolong the lifetime of energy constrained relay nodes in wireless sensor
networks. Its application and related performance study in three-step two-way
decode-and-forward (DF) relay networks are of high interest but still lack
sufficient study. In this paper we propose a dynamic power splitting (PS)
scheme to minimize the system outage probability in a three-step two-way energy
harvesting DF relay network and derive an analytical expression for the system
outage probability with respect to the optimal dynamic PS ratios. In order to
further improve the system outage performance, we propose an improved dynamic
scheme where both the PS ratios and the power allocation ratio at the relay are
dynamically adjusted according to instantaneous channel gains. The
corresponding system performance with the improved dynamic scheme is also
investigated. Simulation results show that our proposed schemes outperform the
existing scheme in terms of the system outage performance and the improved
dynamic scheme is superior to the dynamic PS scheme.
