  This study proposes the construction of a transmit signal for large-scale
antenna systems with cost-effective 1-bit digital-to-analog converters in the
downlink. Under quadrature-amplitude-modulation constellations, it is still an
open problem to overcome a severe error floor problem caused by its nature
property. To this end, we first present a feasibility condition which
guarantees that each user's noiseless signal is placed in the desired decision
region. For robustness to additive noise, we formulate an optimization problem,
we then transform the feasibility conditions to cascaded matrix form. We
propose a low-complexity algorithm to generate a 1-bit transmit signal based on
the proposed optimization problem formulated as a well-defined
mixed-integer-linear-programming. Numerical results validate the superiority of
the proposed method in terms of detection performance and computational
complexity.
