Massive MIMO Relaying with Hybrid Processing

TL;DR

This paper proposes a hybrid analog/digital processing architecture for massive MIMO relaying systems to reduce DSP power and circuitry complexity, demonstrating near-optimal spectral efficiency with low-bit quantized phase shifters.

Contribution

It introduces a hybrid processing scheme that combines analog phase shifters with digital processing, reducing RF chains while maintaining high spectral efficiency.

Findings

Asymptotic spectral efficiency is derived for the hybrid architecture.

Performance loss with 2-bit quantized phase shifters is only 10%.

Hybrid processing significantly reduces hardware complexity.

Abstract

Massive multiple-input multiple-output (MIMO) relaying is a promising technological paradigm which can offer high spectral efficiency and substantially improved coverage. Yet, these configurations face some formidable challenges in terms of digital signal processing (DSP) power consumption and circuitry complexity, since the number of radio frequency (RF) chains may scale with the number of antennas at the relay station. In this paper, we advocate that performing a portion of the power-intensive DSP in the analog domain, using simple phase shifters and with a reduced number of RF paths, can address these challenges. In particular, we consider a multipair amplify-and-forward (AF) relay system with maximum ratio combining/transmission (MRC/MRT) and we determine the asymptotic spectral efficiency for this hybrid analog/digital architecture. After that, we extend our analytical results to account for heavily quantized analog phase shifters and show that the performance loss with 2 quantization bits is only 10%.