Robust massive MIMO Equilization for mmWave systems with low resolution ADCs

TL;DR

This paper evaluates digital beamforming in millimeter wave massive MIMO systems with low-resolution ADCs, demonstrating that sequential DCD outperforms MMSE-based equalization in detection accuracy, complexity, and robustness to channel estimation errors.

Contribution

It introduces a DCD-based MIMO equalization method that surpasses MMSE in performance and complexity for low-resolution ADC millimeter wave systems.

Findings

Sequential DCD outperforms MMSE in detection and complexity.

DCD-based algorithm is more robust to channel estimation errors.

Complexity of MMSE is dominated by Gram matrix computation, not matrix inversion.

Abstract

Leveraging the available millimeter wave spectrum will be important for 5G. In this work, we investigate the performance of digital beamforming with low resolution ADCs based on link level simulations including channel estimation, MIMO equalization and channel decoding. We consider the recently agreed 3GPP NR type 1 OFDM reference signals. The comparison shows sequential DCD outperforms MMSE-based MIMO equalization both in terms of detection performance and complexity. We also show that the DCD based algorithm is more robust to channel estimation errors. In contrast to the common believe we also show that the complexity of MMSE equalization for a massive MIMO system is not dominated by the matrix inversion but by the computation of the Gram matrix.