Energy-Efficient MISO Wireless Powered Communications

This paper considers a multiple-input single-output (MISO) wireless powered communication network (WPCN) and aims to maximize the energy efficiencies (EEs) of the individual users. Specifically, we study user-wise EE maximization problems for TDMA-based WPCN (T-WPCN) and SDMA-based WPCN (S-WPCN), which are both non-convex due to their sum-of-ratios objective functions. We first solve the T-WPCN problem by transforming into a convex parametric problem and obtain its optimal solution by iteratively solving convex problems. Next, we solve the S-WPCN problem by convexifying it using feasible set reduction scheme. We show that T-WPCN outperforms S-WPCN when there is no minimum throughput requirement, while we can observe that S-WPCN outperforms T-WPCN when minimum throughput requirement is high. Simulation results verify our theoretical findings and show the effectiveness of our proposed schemes.