Time Minimization in Downlink Hybrid NOMA Wireless Powered Communication Networks

In this paper, we investigate the time minimization in the downlink (DL) wireless powered transmission network (WPCN) consisting of one base station (BS) and two energy harvesting (EH) users. The hybrid non orthogonal multiple access (H-NOMA) and hybrid EH scheme are adopted, in which each user can harvest energy from both the dedicated energy signal and the information signal for the other user. We aim to minimize the total time consumption under the data rate and energy consumption constraints. To solve the formulated non-convex problem, we propose a two-layer iterative algorithm. The problem in the inner layer is transformed to convex and the problem in the outer layer focused on the power allocation coefficient can be solved by binary search. Simulation results show that H-NOMA can achieve the best performance compared with time-division multiple access (TDMA) and NOMA, and NOMA also outperforms TDMA under the zero circuit power and little decoding power.