Uplink Throughput Maximization for Low Latency in Wireless Powered Communication Networks

Abstract

With the coming of 5G era, wireless transmissions of high data rates in the uplink (UL) are intensely demanded, for supporting low-latency wireless transmissions in various applications. In this paper, a joint downlink (DL) and UL optimization to maximize the sum of UL throughput of devices for a given sum of DL throughput in a wireless powered communication network (WPCN) with two devices is considered. The time frame is divided into two phases: a DL phase followed by a UL phase. In the DL, a hybrid access point (H-AP) first conducts wireless energy transfer (WET) to both devices, and then conducts wireless information transfer (WIT) to each device respectively. In the UL, each device conducts WIT to the H-AP in its allocated time. Each device exploits the total harvested energy from the H-AP in the DL to support its DL information reception and decoding as well as WIT in the UL. We optimize the time allocation for WET and WIT in the DL, WIT for each device in the UL, as well as transmit power of H-AP and devices, so as to maximize total UL throughput of the network for a given DL throughput, subject to energy causality constraints for each device, H-AP’s and each device’s transmit power constraint and time allocation constraint. However, this problem is non-convex and thus is difficult to be solved. To address this difficulty, we transform this problem into a convex optimization problem, and solve it efficiently. Simulation results are also conducted to show the performance of the proposed system.