Optimal User Cooperation in IRS Assisted WPCN for Practical Non-Linear Phase-Shift Model

This letter is a novel attempt to consider intelligent reflecting surfaces (IRS) assisted user cooperation adopting the practical non-linear phase-shift model in a wireless-powered communication network (WPCN). Specifically, we aim to maximize both max-min fairness and sum throughput among the energy harvesting users while adopting the practical IRS model. We propose an alternating optimization (AO) algorithm exploiting convex relaxation and semidefinite programming to optimize the phase-shift matrices at IRS along with time and power allocation at the hybrid access point serving the users. Simulation results corroborate key analytical claims and show that the proposed jointly-optimal design provides better performance gain for max-min and sum-rate maximization over the existing benchmark schemes.