IRS-Enabled Backscattering in a Downlink Non-Orthogonal Multiple Access System

Intelligent reflecting surface (IRS)-enabled backscatter communications can be enabled by an access point (AP) that splits its transmit signal into modulated and unmodulated parts. This letter integrates non-orthogonal multiple (NOMA) with this method to create a two-user primary system secondary of IRS data. Considering the decoding order, we maximize rate strongest user jointly optimizing phase shifts, power splitting (PS) factor at AP, NOMA coefficients while guaranteeing quality service (QoS) for both weak data in systems, respectively. The resulting optimization problem is non-convex. Thus, split it three parts develop alternating (AO) algorithm. advantage derive closed-form solutions PS first two In third part, optimize shifts exploiting semi-definite relaxation (SDR) penalty techniques handle unit-modulus constraints. algorithm achieves substantial gains (e.g., 40–68%) compared relevant baseline schemes.