  We provide new analytical results on the uplink data detection in massive
multiple-input multiple-output systems with 1-bit analog-to-digital converters.
The statistical properties of the soft-estimated symbols (i.e., after linear
combining and prior to the data detection process) have been previously
characterized only for a single user equipment (UE) and uncorrelated Rayleigh
fading. In this paper, we consider a multi-UE setting with correlated Rayleigh
fading, where the soft-estimated symbols are obtained by means of maximum ratio
combining based on imperfectly estimated channels. We derive a closed-form
expression of the expected value of the soft-estimated symbols, which allows to
understand the impact of the specific data symbols transmitted by the
interfering UEs. Building on this result, we design efficient data detection
strategies based on the minimum distance criterion, which are compared in terms
of symbol error rate and complexity.
