An Optimal Low-Complexity Energy-Efficient ADC Bit Allocation for Massive MIMO

Fixed low-resolution Analog to Digital Converters (ADC) help reduce the power consumption in millimeter-wave Massive Multiple-Input Multiple-Output (Ma-MIMO) receivers operating at large bandwidths. However, they do not guarantee optimal Energy Efficiency (EE). It has been shown that adopting variable-resolution (VR) ADCs Ma-MIMO can improve performance with Mean Squared Error (MSE) and throughput while providing better EE. In this paper, we present an energy-efficient bit allocation (BA) algorithm for equipped VR under a constraint. We derive expression EE as function of Cramer-Rao Lower Bound on MSE received, combined, quantized signal. An BA condition is derived by maximizing show thus obtained exactly same using brute-force significant reduction computational complexity. also study complexity heuristic yields near-optimal solution.