  Ambient backscatter communication (AmBC) enables wireless-powered backscatter
devices (BDs) to transmit information over ambient radio-frequency (RF)
carriers without using an RF transmitter, and thus has emerged as a promising
technology for green Internet-of-Things. This paper considers an 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 BDs in a
time-division-multiple-access manner. To enhance the system performance from
multiple design dimensions and ensure fairness, we maximize the minimum
throughput among all BDs by jointly optimizing the BDs' backscatter time
portions, the BDs' power reflection coefficients, and the FAP's subcarrier
power allocation, subject to the LU's throughput constraint, the BDs'
harvested-energy constraints, and other practical constraints. As such, we
propose an efficient iterative algorithm for solving the formulated non-convex
problem by leveraging the block coordinated decent and successive convex
optimization techniques. We further show the convergence of the proposed
algorithm, and analyze its complexity. Finally, extensive simulation results
show that the proposed joint design achieves significant throughput gains as
compared to the benchmark scheme with equal resource allocation.
