Throughput Optimization in FDD MU-MISO Wireless Powered Communication Networks

TL;DR

This paper proposes a throughput optimization scheme for FDD MU-MISO wireless-powered communication networks, balancing energy transfer and data transmission by optimizing CSI feedback and beamforming, with analysis on antenna scaling effects.

Contribution

It introduces a novel optimization framework for rate fairness in FDD WPCNs, incorporating uplink feedback and downlink energy transfer, with an analysis of system behavior as antenna count grows.

Findings

Maximizes minimum data rate among devices.

Provides an iterative solution with convex sub-problems.

Analyzes system performance as the number of antennas increases.

Abstract

In this paper, we consider a frequency-division duplexing (FDD) multiple-user multiple-input-single-output (MU-MISO) wireless-powered communication network (WPCN) consisting of one hybrid data-and-energy access point (HAP) with multiple antennas which coordinates energy/information transfer to/from several single-antenna wireless devices (WD). Typically, in such a system, wireless energy transfer (WET) requires such techniques as energy beamforming (EB) for efficient transfer of energy to the WDs. Yet, efficient EB can only be accomplished if channel state information (CSI) is available to the transmitter, which, in FDD systems is only achieved through uplink (UL) feedback. Therefore, while in our scheme we use the downlink (DL) channels for WET only, the UL channel frames are split into two phases: the CSI feedback phase during which the WDs feed CSI back to the HAP and the WIT phase where the HAP performs wireless information transmission (WIT) via space-division-multiple-access (SDMA). To ensure rate fairness among the WDs, this paper maximizes the minimum WIT data rate among the WDs. Using an iterative solution, the original optimization problem can be relaxed into two sub-problems whose convexity conditions are derived. Finally, the behavior of this system when the number of HAP antennas increases is analyzed. Simulation results verify the truthfulness of our analysis.