Pseudo-random quantization based detection in one-bit massive MIMO systems

2023-1-18
Yılmaz, Gökhan
Analog-to-digital converter (ADC) units are one of the most power-hungry devices in the radio-frequency (RF) chains of massive multiple-input multiple-output (MIMO) systems. Therefore, utilizing low-resolution ADCs in uplink massive MIMO systems is a practical solution to decrease power consumption. However, when high modulation orders are employed for high-rate communication, the achievable rate saturates after a finite SNR value due to the stochastic resonance (SR) phenomenon. This thesis proposes a novel pseudo-random quantization (PRQ) scheme that can help compensate for the effects of SR and makes communication with high-order modulation schemes with one-bit quantization possible. The ADC thresholds at the receiver side of uplink one-bit massive MIMO systems are changed to work with the PRQ scheme. We modify linear detectors for one-bit non-zero threshold quantization and propose new detection methods for the frequency-flat and frequency-selective fading scenarios. For flat fading, we offer a two-stage detector that works with PRQ. The first stage is an iterative method called Boxed Newton Detector (BND) that utilizes Newton's method to maximize the log-likelihood. The second stage, Nearest Codeword Detector (NCD), exploits the first stage to create a small set of most likely candidates based on sign constraints to increase performance. For frequency-selective fading, we design a new frequency-domain equalization (FDE) scheme, called the projected quasi-Newton detector (PQND), to optimize the log-likelihood using a quasi-Newton approach that works with PRQ in both orthogonal frequency division multiplexing (OFDM) and single carrier (SC) systems. The proposed methods outperform the existing detectors with comparable complexity.

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Citation Formats
G. Yılmaz, “Pseudo-random quantization based detection in one-bit massive MIMO systems,” M.S. - Master of Science, Middle East Technical University, 2023.