# Tradeoff Between Delay and High SNR Capacity in Quantized MIMO Systems

## TL;DR

This paper proposes a novel MIMO receiver architecture with delay elements that enhances high SNR capacity under low-resolution ADC constraints, revealing a tradeoff between delay and rate.

## Contribution

It introduces a delay-based analog processing architecture that improves achievable rates in quantized MIMO systems, surpassing prior one-shot methods.

## Key findings

- Achieves maximum transmission rate with fixed one-bit ADCs at high SNR.
- Identifies a tradeoff between delay elements and achievable rate.
- Demonstrates the benefit of blockwise analog combining over one-shot processing.

## Abstract

Analog-to-digital converters (ADCs) are a major contributor to the power consumption of multiple-input multiple-output (MIMO) communication systems with large number of antennas. Use of low resolution ADCs has been proposed as a means to decrease power consumption in MIMO receivers. However, reducing the ADC resolution leads to performance loss in terms of achievable transmission rates. In order to mitigate the rate-loss, the receiver can perform analog processing of the received signals before quantization. Prior works consider one-shot analog processing where at each channel-use, analog linear combinations of the received signals are fed to a set of one-bit threshold ADCs. In this paper, a receiver architecture is proposed which uses a sequence of delay elements to allow for blockwise linear combining of the received analog signals. In the high signal to noise ratio regime, it is shown that the proposed architecture achieves the maximum achievable transmission rate given a fixed number of one-bit ADCs. Furthermore, a tradeoff between transmission rate and the number of delay elements is identified which quantifies the increase in maximum achievable rate as the number of delay elements is increased.