This paper explores the emerging wireless powered communication network, where a hybrid access point (H-AP) with a constant power supply coordinates wireless energy and information transmissions to/from distributed users without other energy sources. The proposed "harvest-then-transmit" protocol involves the H-AP broadcasting wireless energy to users in the downlink (DL) and users transmitting their independent information to the H-AP in the uplink (UL) using time-division-multiple-access (TDMA). The main contributions include: 1. **Sum-Throughput Maximization**: The paper studies the sum-throughput maximization problem by jointly optimizing the time allocation for DL wireless power transfer and UL information transmissions, given a total time constraint. Convex optimization techniques are applied to derive closed-form expressions for the optimal time allocations. The solution reveals a "doubly near-far" phenomenon, where far users receive less energy than near users but must transmit with more power, leading to unfair rate allocation. 2. **Common-Throughput Maximization**: To address the fairness issue, a new performance metric called "common-throughput" is proposed, ensuring equal rates for all users regardless of their distances from the H-AP. An efficient algorithm is presented to solve the common-throughput maximization problem. Simulation results demonstrate the effectiveness of the common-throughput approach in solving the doubly near-far problem. The paper also includes a detailed system model, analysis of the sum-throughput maximization problem, and a discussion on the achievable throughput region under different fairness constraints. The results highlight the trade-offs between sum-throughput and fairness in wireless powered communication networks.This paper explores the emerging wireless powered communication network, where a hybrid access point (H-AP) with a constant power supply coordinates wireless energy and information transmissions to/from distributed users without other energy sources. The proposed "harvest-then-transmit" protocol involves the H-AP broadcasting wireless energy to users in the downlink (DL) and users transmitting their independent information to the H-AP in the uplink (UL) using time-division-multiple-access (TDMA). The main contributions include: 1. **Sum-Throughput Maximization**: The paper studies the sum-throughput maximization problem by jointly optimizing the time allocation for DL wireless power transfer and UL information transmissions, given a total time constraint. Convex optimization techniques are applied to derive closed-form expressions for the optimal time allocations. The solution reveals a "doubly near-far" phenomenon, where far users receive less energy than near users but must transmit with more power, leading to unfair rate allocation. 2. **Common-Throughput Maximization**: To address the fairness issue, a new performance metric called "common-throughput" is proposed, ensuring equal rates for all users regardless of their distances from the H-AP. An efficient algorithm is presented to solve the common-throughput maximization problem. Simulation results demonstrate the effectiveness of the common-throughput approach in solving the doubly near-far problem. The paper also includes a detailed system model, analysis of the sum-throughput maximization problem, and a discussion on the achievable throughput region under different fairness constraints. The results highlight the trade-offs between sum-throughput and fairness in wireless powered communication networks.