Optimal Resource Allocation in Full-Duplex Ambient Backscatter Communication Networks for Green IoT

This paper considers an ambient backscatter communication (AmBC) network in which a full-duplex access point (FAP) simultaneously transmits downlink orthogonal frequency division multiplexing (OFDM) signals to its legacy user (LU) and receives uplink signals backscattered from multiple wireless-powered backscatter devices (BDs) in a time-division-multiple-access manner. To maximize the system throughput and ensure fairness, we aim to maximize the minimum throughput among all BDs by jointly optimizing the backscatter time and reflection coefficients of the BDs, and the FAP's subcarrier power allocation, subject to the LU's throughput constraint, the BDs' harvested-energy constraints, and other practical constraints. However, the formulated problem is non-trivial to solve in general, since the variables are mutually coupled and result in non-convex constraints. We thus propose an iterative algorithm by leveraging the block coordinated decent and successive convex optimization techniques. We further show the convergence performances of the proposed algorithm and analyze its complexity. Finally, extensive simulation results show that the proposed joint design achieves significant throughput gain as compared to the benchmark schemes.