  Simultaneously information and power transfer in mobile relay networks have
recently emerged, where the relay can harvest the radio frequency (RF) energy
and then use this energy for data forwarding and system operation. Most of the
previous works do not consider that the relay may have its own objectives, such
as using the harvested energy for its own transmission instead of maximizing
transmission of the network. Therefore, in this paper, we propose a Nash
bargaining approach to balance the information transmission efficiency of
source-destination pairs and the harvested energy of the relay in a wireless
powered relay network with multiple source-destination pairs and one relay. We
analyze and prove that the Nash bargaining problem has several desirable
properties such as the discreteness and quasi-concavity, when it is decomposed
into three sub-problems: the energy transmission power optimization, the power
control for data transmission and the time division between energy transmission
and data transmission. Based on the theoretical analysis, we propose an
alternating power control and time division algorithm to find a suboptimal
solution. Simulation results clearly show and demonstrate the properties of the
problem and the convergence of our algorithm.
