  In this paper, we consider simultaneous wireless information and power
transfer (SWIPT) in relay interference channels, where multiple
source-destination pairs communicate through their dedicated energy harvesting
relays. Each relay needs to split its received signal from sources into two
streams: one for information forwarding and the other for energy harvesting. We
develop a distributed power splitting framework using game theory to derive a
profile of power splitting ratios for all relays that can achieve a good
network-wide performance. Specifically, non-cooperative games are respectively
formulated for pure amplify-and-forward (AF) and decode-and-forward (DF)
networks, in which each link is modeled as a strategic player who aims to
maximize its own achievable rate. The existence and uniqueness for the Nash
equilibriums (NEs) of the formulated games are analyzed and a distributed
algorithm with provable convergence to achieve the NEs is also developed.
Subsequently, the developed framework is extended to the more general network
setting with mixed AF and DF relays. All the theoretical analyses are validated
by extensive numerical results. Simulation results show that the proposed
game-theoretical approach can achieve a near-optimal network-wide performance
on average, especially for the scenarios with relatively low and moderate
interference.
