  In this paper, we investigate the massive MIMO relay system, where the relay
station (RS) forwards the signals from multiple remote users to the base
station (BS). Large-scale antenna arrays in conjunction with low-resolution
analog-to-digital converters (ADCs) are equipped at the RS and the BS to
guarantee the high spectral efficiency with low cost. Considering the
ever-present spatial correlation at both the RS and the BS, we first study the
canonical channel estimation process, from which a tractable equivalent form of
the channel estimate is extracted for further analysis. Under these
transmission impairments along with the ADC quantization imperfection, we
derive the closed-form approximation of the achievable rate. Then the impacts
of power scaling, spatial correlation level, and ADC resolution bits are
revealed comprehensively to guide the practical system deployment and
implementation. Numerical results are presented to verify the theoretical
analysis in a straightforward way.
