Common Throughput Maximization with Hybrid NOMA in Wireless Powered Communication Networks

This paper focuses on wireless powered communication networks (WPCNs), where one hybrid sink (H-sink) coordinates the wireless energy/information transmissions to/from a set of one-hop nodes powered by the harvested radio-frequency (RF) energy only, and aims to maximize the common throughput (CT) of nodes. Specifically, we explore WPCNs employing hybrid non-orthogonal multiple access (NOMA), where all nodes are divided into pairs and the nodes in the same pair transmit information concurrently to H-sink. Successive interference cancellation (SIC) is performed at H-sink to alleviate the interference from the other node. Pairing selection, decoding order of nodes’ signals, wireless energy transfer (WET) time and wireless information transmit (WIT) time of each pair are jointly optimized to maximize the CT. We first formulate the CT maximization (CTM) as a non-convex optimization problem, and then present a framework for solving problems of hybrid NOMA-based WPCNs. Applying this framework, we decompose the CTM problem into two parts: the master problem obtaining optimal pairing, and the slave convex optimization problem obtaining the minimized time required for each pair. The master problem is solved by maximum weighted matching algorithm. Simulation results demonstrate that the shift hybrid NOMA-based scheme outperforms the basic hybrid NOMA-based scheme and the time division multiple access (TDMA) based scheme.