  This letter revisits the channel estimation problem for MIMO systems with
one-bit analog-to-digital converters (ADCs) through a novel
algorithm--Amplitude Retrieval (AR). Unlike the state-of-the-art methods such
as those based on one-bit compressive sensing, AR takes a different approach.
It accounts for the lost amplitudes of the one-bit quantized measurements, and
performs channel estimation and amplitude completion jointly. This way, the
direction information of the propagation paths can be estimated via accurate
direction finding algorithms in array processing, e.g., maximum likelihood. The
upsot is that AR is able to handle off-grid angles and provide more accurate
channel estimates. Simulation results are included to showcase the advantages
of AR.
