IRS-Aided WPCNs: A New Optimization Framework for Dynamic IRS Beamforming

In this paper, we propose a new dynamic IRS beamforming framework to boost the sum throughput of an intelligent reflecting surface (IRS) aided wireless powered communication network (WPCN). Specifically, phase-shift vectors across time and resource allocation are jointly optimized enhance efficiencies both downlink power transfer (DL WPT) uplink information transmission (UL WIT) between hybrid access point (HAP) multiple wirelessly devices. To end, first study three special cases beamforming, namely xmlns:xlink="http://www.w3.org/1999/xlink">user-adaptive xmlns:xlink="http://www.w3.org/1999/xlink">UL-adaptive xmlns:xlink="http://www.w3.org/1999/xlink">static , by characterizing their optimal performance relationships proposing corresponding algorithms. Interestingly, it is rigorously proved that latter two achieve same throughput, thus helping halve number phase shifts be signalling overhead practically required for UL-adaptive beamforming. Then, general optimization which applicable any given available. Despite non-convexity problem with highly coupled variables, algorithms solve particularly, low-complexity algorithm exploits intrinsic structure solution as well solutions user-adaptive static Simulation results validate our theoretical findings, illustrate practical significance beamforming spectral energy efficient WPCNs, demonstrate effectiveness proposed designs over various benchmark schemes.