Low complexity resource allocation in the relay channels with energy harvesting transmitters

Energy Harvesting (EH) is a novel technique to prolong the lifetime of the wireless Ad-hoc and sensor networks with replenishable nodes. In this sense, it has emerged as a promising technique for Green Communications. On the other hand, cooperative communication with the help of relay nodes improves the performance of wireless communication networks. In this paper, we investigate the cooperation in EH nodes. We consider the optimal power and rate allocation in the full-duplex Gaussian relay channel in which source and relay can harvest energy from their environments. In our model, the energy arrivals at the source and the relay are general stochastic processes with known EH times and amounts before the start of transmission. This problem has a constrained min-max optimization form that is not easy to solve. We propose a method based on a mathematical theorem to decompose it into two problems: the first problem has a tractable convex optimization form and can be solved efficiently. We show that the second problem is an unconstrained discrete convex optimization problem, which has the complexity of O(K2), instead of O(2K), where K is the dimension of variables. Also, we provide some numerical examples that confirm our results.