Energy harvesting for relay-assisted communications

In this paper, we examine the problem of throughput maximization in an energy-harvesting two-hop amplify-and-forward relay network. This problem is investigated over a finite time horizon and in an online setting, where the causal knowledge of the harvested energy and that of fading are available. We use Markov decision process (MDP) formulation to present a mathematically tractable solution to the throughput maximization problem. In this solution, optimal power-use policy is obtained using backward induction algorithm of the corresponding discrete dynamic programming problem. We also present properties of the optimal policy for an important special case, where the power control at transmitters is limited to on-off switching. These properties facilitate the implementation of the MDP based solution. Our numerical simulations show that the proposed method outperforms existing solutions to this problem.