QoS-Guaranteed Adaptive Power Reflection Coefficient for Self-Powered Cooperative Ambient Backscatter Communication

In cooperative ambient backscatter communication systems, the power reflection coefficient (PRC) affects the outage probabilities (OPs) of both the primary transmitter (PT) and the backscatter device (BD), as well as the harvested energy of the BD. Considering the BD’s energy-causality constraint, we propose two quality-of-service (QoS)-guaranteed adaptive power reflection coefficient (PRC) strategies to minimize the BD’s OP, and closed-form expressions are obtained for the corresponding optimal PRCs. In addition, exact yet concise expressions for the BD’s OP are derived to evaluate the proposed PRC strategies. Simulation results verify the superiority of the proposed PRC strategies and validate the correctness of the analytical results.