Joint Power and Reflecting Elements Optimization for Intelligent Reflecting Surface Assisted NOMA

Abstract

This paper presents a joint power and number of intelligent reflecting surfaces (IRS) elements optimization in an IRS-assisted non-orthogonal multiple access (NOMA) network. The proposed optimized IRS NOMA (OIRS-NOMA) solution finds the optimal number of IRS elements and the power allocation factors with log-time complexity. Furthermore, the pair sum rate (PSR) is maximized while satisfying the required individual user rates. In addition, the proposed and the existing IRS-NOMA systems are analyzed under the fixed power allocation (FPA) and optimized power allocation (OPA) schemes. Finally, a comparison of the proposed (OIRS-NOMA), the conventional IRS-NOMA, and NOMA techniques is performed in detail. Simulation results show that the proposed OIRS-NOMA outperforms the existing IRS-NOMA and NOMA techniques in terms of individual user rates and PSR.