Spectral- and Energy-Efficient Hybrid Receivers for Millimeter-Wave Massive Multiuser MIMO Uplink Systems With Variable-Resolution ADCs

A primary difficulty in the practical implementation of millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems is the high hardware complexity and power consumption imposed by the employment of a large number of antennas at the base station. To alleviate this difficulty, we concentrate on a hybrid beamforming architecture consisting of less number of radio-frequency chains with variable-resolution analog-to-digital converters (ADCs) for mmWave massive multiuser MIMO uplink systems. Our objective is to design the ADC resolution profile to maximize system performance while reducing total receiver power consumption. However, the resulting ADC resolution profile design problem incurs high combinatorial complexity and is known to be computationally intractable. We address this problem by devising a simple yet computationally efficient algorithm, namely a coordinate update algorithm, to design the ADC resolution profile. Simulation results show that the proposed algorithm not only provides nearly the same sum rate as full-precision ADC receiver systems but also achieves much higher energy efficiency than existing state-of-the-art receiver architectures.