Colosseum: The Open RAN Digital Twin

TL;DR

Colosseum presents a high-fidelity Open RAN digital twin built on a large hardware-in-the-loop wireless emulator, enabling end-to-end Open RAN stacks and real-time twinning. It integrates open-source protocol stacks, the OpenRAN Gym toolkit, and CaST RF channel emulation to deliver realistic, repeatable experiments and data for training AI/ML controllers. The paper details the twin architecture, automated pipelines, and cross-platform interoperability, and showcases use cases in slicing, spectrum sharing, explainable AI, wireless-backhaul optimization, and security testing. By enabling safe testing and transfer of experiments to real testbeds (e.g., Arena) and PAWR platforms, Colosseum aims to accelerate Open RAN development, testing, and certification. The work highlights practical pathways to dataset generation, model validation, and vendor interoperability in programmable cellular networks.

Abstract

Recent years have witnessed the Open Radio Access Network (RAN) paradigm transforming the fundamental ways cellular systems are deployed, managed, and optimized. This shift is led by concepts such as openness, softwarization, programmability, interoperability, and intelligence of the network, all of which had never been applied to the cellular ecosystem before. The realization of the Open RAN vision into practical architectures, intelligent data-driven control loops, and efficient software implementations, however, is a multifaceted challenge, which requires (i) datasets to train Artificial Intelligence (AI) and Machine Learning (ML) models; (ii) facilities to test models without disrupting production networks; (iii) continuous and automated validation of the RAN software; and (iv) significant testing and integration efforts. This paper poses itself as a tutorial on how Colosseum - the world's largest wireless network emulator with hardware in the loop - can provide the research infrastructure and tools to fill the gap between the Open RAN vision, and the deployment and commercialization of open and programmable networks. We describe how Colosseum implements an Open RAN digital twin through a high-fidelity Radio Frequency (RF) channel emulator and end-to-end softwarized O-RAN and 5G-compliant protocol stacks, thus allowing users to reproduce and experiment upon topologies representative of real-world cellular deployments. Then, we detail the twinning infrastructure of Colosseum, as well as the automation pipelines for RF and protocol stack twinning. Finally, we showcase a broad range of Open RAN use cases implemented on Colosseum, including the real-time connection between the digital twin and real-world networks, and the development, prototyping, and testing of AI/ML solutions for Open RAN.

Figures (8)

• Figure 1: Open RAN twinning capabilities in Colosseum
• Figure 2: Intelligent Control Loops with Colosseum, based on the OpenRAN Gym framework bonati2022openrangym-pawr.
• Figure 3: scenario creation (top) and scenario validation (bottom) workflows.
• Figure 4: Ansible pipeline to perform an automated test on Colosseum.
• Figure 5: An overview depicting how the MQTT communication broker facilitates bidirectional data distribution to specific processes, enabling scalable implementation of digital twins.