  In this paper, we propose a new distributed energy beamforming and
information transfer (DEBIT) scheme for realizing simultaneous wireless
information and power transfer (SWIPT) in multiway relay networks (MWRNs),
where multiple single-antenna users exchange information via an
energy-constrained single-antenna relay node. We investigate the optimal
transceiver designs to maximize the achievable sum-rate or the harvested power.
The resultant sum-rate maximization problem is non-convex and the global
optimal solution can be obtained through a three-dimensional search in
combination with conventional convex optimization. To reduce the computation
complexity, a suboptimal DEBIT scheme is also proposed, for which the
optimization problem becomes linear programming. The achievable sum-rate
performance is analyzed and a closed-form lower bound is derived for the MWRN
with a large number of users. Furthermore, we consider the harvested-power
maximization problem under a target sum-rate constraint, and derive a lower
bound of the average harvested power for MWRNs with a large number of users.
Numerical results show that the DEBIT scheme significantly outperforms the
conventional SWIPT and the derived lower bounds are tight.
