  The high hardware complexity of a massive MIMO base station, which requires
hundreds of radio chains, makes it challenging to build commercially. One way
to reduce the hardware complexity and power consumption of the receiver is to
lower the resolution of the analog-to-digital converters (ADCs). We derive an
achievable rate for a massive MIMO system with arbitrary quantization and use
this rate to show that ADCs with as low as 3 bits can be used without
significant performance loss at spectral efficiencies around 3.5 bpcu per user,
also under interference from stronger transmitters and with some imperfections
in the automatic gain control.
