# Multipair Massive MIMO Relaying Systems with One-Bit ADCs and DACs

## TL;DR

This paper analyzes a multipair massive MIMO relay system with one-bit ADCs and DACs, deriving achievable rate expressions, power scaling laws, and strategies to mitigate quantization effects, highlighting the impact of coarse quantization on system performance.

## Contribution

It provides an exact achievable rate analysis and asymptotic approximation for one-bit quantized massive MIMO relays, including power scaling laws and a power allocation strategy to improve performance.

## Key findings

- Achievable rate depends on pilot sequence choice, unlike unquantized systems.
- The sum rate gap with an ideal system is about 4/π² in low power regimes.
- Power allocation can mitigate rate degradation caused by coarse quantization.

## Abstract

This paper considers a multipair amplify-and-forward massive MIMO relaying system with one-bit ADCs and one-bit DACs at the relay. The channel state information is estimated via pilot training, and then utilized by the relay to perform simple maximum-ratio combining/maximum-ratio transmission processing. Leveraging on the Bussgang decomposition, an exact achievable rate is derived for the system with correlated quantization noise. Based on this, a closed-form asymptotic approximation for the achievable rate is presented, thereby enabling efficient evaluation of the impact of key parameters on the system performance. Furthermore, power scaling laws are characterized to study the potential energy efficiency associated with deploying massive one-bit antenna arrays at the relay. In addition, a power allocation strategy is designed to compensate for the rate degradation caused by the coarse quantization. Our results suggest that the quality of the channel estimates depends on the specific orthogonal pilot sequences that are used, contrary to unquantized systems where any set of orthogonal pilot sequences gives the same result. Moreover, the sum rate gap between the double-quantized relay system and an ideal non-quantized system is a moderate factor of $4/\pi^2$ in the low power regime.