Throughput Maximization for Multi-Hop Decode-and-Forward Relay Network with Wireless Energy Harvesting

In this paper, we consider multi-hop wireless networks with decode-and-forward relays. Intermediate relays have no fixed power supplies and thus need to replenish energy via wireless energy harvesting from the source signal. The technique of simultaneous wireless information and power transfer (SWIPT) is utilized between every two adjacent nodes to transport both information and energy. Three general protocols of SWIPT are considered: power-splitting (PS), time-switching (TS), and hybrid which is a combination of PS and TS protocols. For each protocol, we formulate optimization problems to decide optimal PS and TS ratios so as to maximize end-to-end throughput under two schemes. Scheme 1 allows different PS and TS ratios at each relay, and Scheme 2 uses uniform PS and TS ratios for all the relays. The proposed optimization problems are shown to be non-convex. With a series of transformations, we turn the proposed non-convex optimization problems to be convex ones. Insightful analysis of the system performance is presented in the part of numerical results.