Fairness-Aware Multiuser Scheduling for Finite-Resolution Intelligent Reflecting Surface-Assisted Communication

Abstract

This letter investigates multiuser scheduling for finite-resolution intelligent reflecting surface (IRS)-assisted communication systems with fairness guarantee. Different from previous works, we consider the interference-free transmission among multiple users, and propose a new phase shift scheme referred to as hybrid phase shift (HPS), which generalizes the conventional coherent phase shift (CPS) and random phase shift (RPS) and makes a tradeoff between the capacity performance and the feedback overhead for the channel phase information (CPI). Our goal is to maximize the minimum ergodic capacity among multiple users subject to the transmission time constraint. However, it does not admit an exact closed-form expression for the ergodic capacity in the proposed HPS, where its approximation is obtained to facilitate the time allocation. To shed light on the practical design, the number of reflecting elements that can guarantee a given capacity performance gap between CPS and HPS is investigated. Simulation results show the tightness of derived ergodic capacities, and demonstrate the capacity-feedback tradeoff for the proposed HPS.