Convexity of Fairness-Aware Resource Allocation in Wireless Powered Communication Networks

This letter focuses on fairness-aware power and time allocation in wireless powered communication networks under the "harvest-then-transmit" protocol, where downlink wireless energy transfer is implemented at first and then uplink wireless information transfer takes place in a spectrum-sharing fashion. We aim to achieve the rate fairness of all users under three fairness criteria named max-min, proportional, and harmonic fairness. Although these problems are intractable in their original nonconvex formulations, all of them can be equivalently transformed to convex programming ones. As a result, the global optimal solution can be efficiently obtained via mature convex solvers. Simulation results verify the effectiveness of the proposed approach in terms of minimum-rate, geometric mean rate, and mean delay.