  In this letter, we investigate the uplink of a reconfigurable intelligent
surface (RIS)-aided millimeter-wave (mmWave) multi-user system. In the
considered system, however, problems with hardware cost and power consumption
arise when massive antenna arrays coupled with power-demanding
analog-to-digital converters (ADCs) are employed. To account for practical
hardware complexity, we consider that the access point (AP) is equipped with
resolution-adaptive analog-to-digital converters (RADCs). We maximize the
achievable rate under hardware constraints by jointly optimizing the ADC
quantization bits, the RIS phase shifts, and the beam selection matrix. Due to
the non-convexity of the feasible set and objective function, the formulated
problem is non-convex and difficult to solve. To efficiently tackle this
problem, a block coordinated descent (BCD)-based algorithm is proposed.
Simulations demonstrate that an RIS can mitigate the hardware loss due to use
of RADCs, and that the proposed BCD-based algorithm outperforms
state-of-the-art algorithms.
