Max-Min Fairness Energy Efficiency for Multi-User MIMO Wireless Powered Communication Networks

In this paper, we consider max-min energy efficiency for multiple-input multiple-output wireless powered communication networks (MIMO WPCN), where all users first harvest energy from a dedicated radio frequency power source in the downlink phase and then use the harvested power for sending their information under the harvest then transmit protocol in the uplink phase. The goal is to provide fairness in the network through maximizing the users' minimum energy efficiency by optimal design of energy and information covariance matrices, and optimal time allocation to downlink and uplink phases. This problem is non-convex, and we thus propose an algorithm that optimizes a set of parameters at each step by considering other parameters as constants. The simulation results show the effectiveness of the method.