  In this paper, we study the outage performance of simultaneous wireless
information and power transfer (SWIP- T) based three-step two-way
decode-and-forward (DF) relay networks, where both power-splitting (PS) and
harvest-then-forward are employed. In particular, we derive the expressions of
terminal-to-terminal (T2T) and system outage probabilities based on a
Gaussian-Chebyshev quadrature approximation, and obtain the T2T and system
outage capacities. The effects of various system parameters, e.g., the static
power allocation ratio at the relay, symmetric PS, as well as asymmetric PS, on
the outage performance of the investigated network are examined. It is shown
that our derived expression for T2T outage capacity is more accurate than
existing analytical results, and that the asymmetric PS achieves a higher
system outage capacity than the symmetric one when the channels between the
relay node and the terminal nodes have different statistic gains.
