Mixed-ADC Massive MIMO

Abstract

Motivated by the demand for energy-efficient communication solutions in the next generation cellular network, a mixed-ADC architecture for massive multiple input multiple output (MIMO) systems is proposed, which differs from previous works in that herein one-bit analog-to-digital converters (ADCs) partially replace the conventionally assumed high-resolution ADCs. The information-theoretic tool of generalized mutual information (GMI) is exploited to analyze the achievable data rates of the proposed system architecture and an array of analytical results of engineering interest are obtained. For fixed single input multiple output (SIMO) channels, a closed-form expression of the GMI is derived, based on which the linear combiner is optimized. The analysis is then extended to ergodic fading channels, for which tight lower and upper bounds of the GMI are obtained. Impacts of dithering and imperfect channel state information (CSI) are also investigated, and it is shown that dithering can remarkably improve the system performance while imperfect CSI only introduces a marginal rate loss. Finally, the analytical framework is applied to the multi-user access scenario. Numerical results demonstrate that the mixed-ADC architecture with a relatively small number of high-resolution ADCs is able to achieve a large fraction of the channel capacity of conventional architecture, while reduce the energy consumption considerably even compared with antenna selection, for both single-user and multi-user scenarios.Comment: double column, 15 pages, 11 figures, accepted for publication in IEEE Journal on Selected Areas in Communications Special Issue on Energy-Efficient Techniques for 5G Wireless Communication System

Quantized Massive MU-MIMO-OFDM Uplink

“…In summary, the results in [4], [7], [8], [11] suggest that massive MU-MIMO provides resilience against noise caused by coarse quantization. However, all these results pertain to massive MU-MIMO systems operating over frequency-flat fading channels.…”

“…Liang and Zhang [11] considered a mixed-ADC massive MU-MIMO architecture, where few high-resolution ADCs are used together with many 1-bit ADCs. The high-resolution ADCs allow the receiver to acquire accurate channel-state information (CSI).…”

“…Generalized mutual information was used to characterize the performance of this architecture for the case of Gaussian codebooks and mismatched nearest-neighbor decoding. In [11], it is also noted that dithering prior to quantization may help improving the performance.…”

“…The pilot matrices T w are generated from a U × U orthonormal Hadamard transform matrix, where the signs of the columns and rows are randomly altered. 11 The quantization alphabet A c and the quantization bin boundaries {b q } are set using the Lloyd-Max algorithm [54], [55]. For a given set of system parameters, the algorithm uses an estimate of the probability density function of the received signal, which is acquired offline.…”

A Survey of Energy-Efficient Techniques for 5G Networks and Challenges Ahead

“…The paper [145], as an instance, presents an analysis of the spectral efficiency of single-carrier and OFDM transmission in massive MIMO systems that use one-bit analog-to-digital converters (ADCs), while a capacity analysis of one-bit quantized MIMO systems with transmitter CSI is reported in [146]. One-bit ADCs coupled with high-resolution ADCs are instead proposed and analyzed in the paper [147], from this special issue, to simplify receiver design in massive MIMO systems. The paper shows that the proposed mixed-ADC architecture with a relatively small number of high-resolution ADCs is able to achieve a large fraction of the channel capacity of the conventional architecture, while reducing the energy consumption considerably even compared with antenna selection strategies, for both single-user and multi-user scenarios.…”