User-centric energy-efficient resource allocation for wireless powered communications

This paper considers wireless powered communication networks (WPCNs), where mobile users first harvest energy from a dedicated power station and then communicate with an information receiving station. We aim to maximize the weighted sum of user-centric energy efficiency (WSUEE) via joint time allocation and power control in both downlink and uplink. The proposed approach provides the flexibility of assigning users different levels of importance so that the individual user EEs can be balanced. The WSUEE maximization problem is investigated for a generalized WPCN where each user is equipped with initial energy and also has a minimum throughput requirement. By exploiting the special structure of the objective function, the considered problem is then transformed into a convex problem that can be solved efficiently. Simulation results verify our theoretical findings and demonstrate the effectiveness of the proposed approach.