QoS-Aware Resource Allocation of RIS-Aided Multi-User MISO Wireless Communications

Abstract

In this article, it is investigated a multi-user multiple-input single-output wireless communication scenario (MISO) in which a base station (BS) serves multiple users with the assistance of a reconfigurable intelligent surface (RIS). Specifically, the delay sensitivity QoS aware total effective capacity (TEC) is maximized. By employing Zero-Forcing (ZF) beamforming at the BS, the beamforming optimization is converted the power allocation. Then, we alternately optimize QoS provisioning power allocation schemes and RIS phase shifts. In particular, we derive a closed-form expression for the optimal power allocation scheme based on the Lagrangian method and the Karoosh-Koon-Tucker (KKT) condition. Meanwhile, the RIS phase shift strategy is optimized by employing the gradient descent method. Finally, the performance of the proposed joint optimal schemes for RIS-assisted wireless communication is verified by simulations. The simulation results demonstrate that the optimization scheme effectively guarantees the user's delay QoS requirements and the TEC significantly outperforms the random reflecting phase shift scheme.