  We analyze the performance of multiple-input multiple-output (MIMO) links
with one-bit output quantization in terms of achievable rates and characterize
their performance loss compared to unquantized systems for general channel
statistical models and general channel state information (CSI) at the receiver.
One-bit ADCs are particularly suitable for large-scale millimeter wave MIMO
Communications (massive MIMO) to reduce the hardware complexity. In such
applications, the signal-to-noise ratio per antenna is rather low due to the
propagation loss. Thus, it is crucial to analyze the performance of MIMO
systems in this regime by means of information theoretical methods. Since an
exact and general information-theoretic analysis is not possible, we resort to
the derivation of a general asymptotic expression for the mutual information in
terms of a second order expansion around zero SNR. We show that up to second
order in the SNR, the mutual information of a system with two-level (sign)
output signals incorporates only a power penalty factor of pi/2 (1.96 dB)
compared to system with infinite resolution for all channels of practical
interest with perfect or statistical CSI. An essential aspect of the derivation
is that we do not rely on the common pseudo-quantization noise model.
