Uplink Data Rate Maximization in Multi-Cell BackCom NOMA Systems

Abstract

This paper investigates a backscatter communication (BackCom) non-orthogonal multiple access (NOMA) system with numerous base stations (BSs) and backscatter devices (BDs). The objective is to maximize sum uplink rate by adjusting reflection coefficients of BDs and establishing association policies between BSs and BDs. To achieve this, matching theory is utilized to address the association problem, and a quadratic transform iterative algorithm is employed to calculate optimal reflection coefficients under a given association policy. Meanwhile, hybrid successive interference cancellation (SIC) is applied to reduce the outage probability of the proposed system while optimizing the uplink sum data rate, where a low-complexity solution is developed. Simulation results validate the superiority of the proposed optimization scheme in enhancing uplink sum data rate. The comparison between BackCom NOMA and BackCom orthogonal multiple access (OMA) reveals superior performance of the former, which becomes increasingly evident as the number of BSs and BDs increases. The proposed iterative algorithm significantly enhances the system's sum uplink data rate. The usage of hybrid SIC also notably declines the outage probability of the system.