  In this paper, a wireless cooperative network is considered, in which
multiple source-destination pairs communicate with each other via an energy
harvesting relay. The focus of this paper is on the relay's strategies to
distribute the harvested energy among the multiple users and their impact on
the system performance. Specifically, a non-cooperative strategy is to use the
energy harvested from the i-th source as the relay transmission power to the
i-th destination, to which asymptotic results show that its outage performance
decays as logSNR over SNR. A faster decaying rate, 1 over SNR, can be achieved
by the two centralized strategies proposed this the paper, where the water
filling based one can achieve optimal performance with respect to several
criteria, with a price of high complexity. An auction based power allocation
scheme is also proposed to achieve a better tradeoff between the system
performance and complexity. Simulation results are provided to confirm the
accuracy of the developed analytical results and facilitate a better
performance comparison.
