Outage probability for two-way relay networks with stochastic energy harvesting source nodes

The long-term outage probability and optimal transmission policy are investigated for the energy harvesting (EH) two-way relay (TWR) network by exploiting a real-data-driven stochastic EH model. In the EH TWR network, two solar-powered source nodes are both equipped with finite-sized batteries, and communicate with each other under the assistance of a conventional relay node. The framework is formulated as a Markov decision process (MDP), and the optimal transmission power values of the two EH nodes are both computed to minimize the long-term outage probability of the network by considering the causal EH condition, the random channel status and the energy amount of the two batteries. In addition, a two-dimensional on-off threshold structure for the optimal transmission policy is uncovered, and then the outage performance limit of the network is presented, in that the long-term outage probability eventually approaches to the deficiency probability of network batteries in sufficiently high SNRs. Computer simulations are demonstrated to verify the theoretical analysis.