User Scheduling for Millimeter Wave MIMO Communications with Low-Resolution ADCs

To reduce power consumption in the receiver, low-resolution analog-to-digital converters (ADCs) can be a potential solution for millimeter wave (mmWave) systems in which many antennas are likely to be deployed to compensate for the large path loss. In this paper, we investigate uplink user scheduling when a basestation employs low-resolution ADCs with a large number of antennas. Due to quantization error, we show that the channel structure in the beamspace, in addition to the channel magnitude and beamspace orthogonality, plays a key role in maximizing the achievable rates of scheduled users. With the constraint of the equal channel norm, we derive the scheduling criteria that maximize the uplink sum rate for multiuser multiple input multiple output (MIMO) systems with a zero-forcing receiver. Leveraging the derived criteria, we propose an efficient scheduling algorithm for mmWave systems with low-resolution ADCs. Numerical results validate that the proposed algorithm outperforms conventional user scheduling methods in terms of the sum rate.