Intelligent STAR‐RIS‐Assisted NOMA Networks With Backscatter Coexistence: Outage Analysis and Interference Mitigation

Abstract In this work, a novel simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR‐RIS) assisted non‐orthogonal multiple access (NOMA) network coexists with an ambient backscatter communication network. In the proposed framework, an AP uses a STAR‐RIS to communicate with two users, and a backscatter device uses the transmitting signal from the STAR‐RIS to send information to its backscatter receiver simultaneously. The transmission of backscatter device creates interference to both NOMA users, while the signal traveling through the STAR‐RIS transmission path create an interfere to the BR also. Analytical expressions for the achievable throughput and outage probability under Nakagami‐ fading are derived in order to describe the system performance. A closed‐form equation and its asymptotic approximation are developed after an analytical investigation of the outage performance of the proposed STAR‐RIS‐assisted NOMA‐backscatter network in order to further improve the resilience of the system. The residual interference factor is then continuously adjusted by an adaptive interference mitigation algorithm based on SINR feedback, guaranteeing the effective achievement of the desired SINR. In contrast to fixed or no mitigation approaches, the results demonstrate that adaptive mitigation greatly lowers the outage probability, demonstrating the effectiveness of interference‐aware control in maintaining reliable communication under varying interference scenarios.