NL-COMM: Demonstrating Gains of Non-Linear Processing in Open-RAN Ecosystem

TL;DR

This paper demonstrates a real-time, software-based non-linear processing framework for MU-MIMO in Open-RAN, achieving higher throughput and connectivity with fewer antennas, and integrating rate adaptation for practical deployment.

Contribution

It introduces NL-COMM, a novel non-linear processing framework that operates in real-time within a standard-compliant Open-RAN ecosystem, including the first practical rate adaptation for NL processing.

Findings

Supports four MIMO streams with a single antenna

Halves the number of antennas needed without performance loss

Meets 5G-NR real-time latency requirements

Abstract

Multi-user multiple-input, multiple-output (MU-MIMO) designs can substantially increase wireless systems' achievable throughput and connectivity capabilities. However, existing MU-MIMO deployments typically utilize linear processing techniques that, despite their practical benefits, such as low computational complexity and easy integrability, can leave much of the available throughput and connectivity gains unexploited. They typically require many power-intensive antennas and RF chains to support a smaller number of MIMO streams, even when the transmitted information streams are of low rate. Alternatively, non-linear (NL) processing methods can maximize the capabilities of the MIMO channel. Despite their potential, traditional NL methods are challenged by high computational complexity and processing latency, making them impractical for real-time applications, especially in software-based systems envisioned for emerging Open Radio Access Networks (Open-RAN). Additionally, essential functionalities such as rate adaptation (RA) are currently unavailable for NL systems, limiting their practicality in real-world deployments. In this demo, we present the latest capabilities of our advanced NL processing framework (NL-COMM) in real-time and over-the-air, comparing them side-by-side with conventional linear processing. For the first time, NL-COMM not only meets the practical 5G-NR real-time latency requirements in pure software but also does so within a standard-compliant ecosystem. To achieve this, we significantly extended the NL-COMM algorithmic framework to support the first practical RA for NL processing. The demonstrated gains include enhanced connectivity by supporting four MIMO streams with a single base-station antenna, substantially increased throughput, and the ability to halve the number of base-station antennas without any performance loss to linear approaches.