Quantized Massive MU-MIMO-OFDM Uplink

TL;DR

This paper explores the uplink performance of wideband massive MU-MIMO-OFDM systems with coarse quantization, proposing new algorithms that achieve near-infinite precision performance with minimal complexity increase.

Contribution

It introduces novel algorithms for quantized MAP channel estimation and data detection in wideband MU-MIMO-OFDM systems, addressing a less studied practical scenario.

Findings

Coarse quantization (4-6 bits) causes negligible performance loss.

Proposed algorithms effectively handle frequency-selective channels.

Performance approaches infinite-precision systems without added complexity.

Abstract

Coarse quantization at the base station (BS) of a massive multi-user (MU) multiple-input multiple-output (MIMO) wireless system promises significant power and cost savings. Coarse quantization also enables significant reductions of the raw analog-to-digital converter (ADC) data that must be transferred from a spatially-separated antenna array to the baseband processing unit. The theoretical limits as well as practical transceiver algorithms for such quantized MU-MIMO systems operating over frequency-flat, narrowband channels have been studied extensively. However, the practically relevant scenario where such communication systems operate over frequency-selective, wideband channels is less well understood. This paper investigates the uplink performance of a quantized massive MU-MIMO system that deploys orthogonal frequency-division multiplexing (OFDM) for wideband communication. We propose new algorithms for quantized maximum a-posteriori (MAP) channel estimation and data detection, and we study the associated performance/quantization trade-offs. Our results demonstrate that coarse quantization (e.g., four to six bits, depending on the ratio between the number of BS antennas and the number of users) in massive MU-MIMO-OFDM systems entails virtually no performance loss compared to the infinite-precision case at no additional cost in terms of baseband processing complexity.