ProtO-RU: An O-RAN Split-7.2 Radio Unit using SDRs

2025-12-02

AI Summary

End-to-end O-RAN research is hindered by proprietary O-RU hardware and the high barrier to innovation at the RU layer. Method: This paper designs and implements ProtO-RU—the first open-source, software-defined Split-7.2 radio unit—built on commodity CPUs and commercial SDR hardware, integrating the srsRAN protocol stack. It supports TDD/FDD duplexing, dynamic fronthaul interface reconfiguration, and interoperability with multiple DU/CU ecosystems. Contribution/Results: Experiments demonstrate stable operation under sustained multi-user load, throughput comparable to Split-8 implementations and commercial O-RUs, and successful interoperability with commercial 5G user equipment. ProtO-RU significantly reduces R&D and validation costs for O-RAN RU-level development, establishing a foundational infrastructure that enables programmability, flexibility, and collaborative innovation in open RAN.

Technology Category

• Planning, Routing, and Scheduling: Routing
• Machine Learning: Hardware-aware ML
• Search and Optimization: Distributed Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Data transparency and provenance
• Responsible Web: Data and user privacy-enhancing technologies for the Web

Abstract

We present ProtO-RU, the first open source, software-defined O-RAN Split-7.2 Radio Unit built using SDRs and commodity CPUs. Unlike proprietary hardware-based commercial O-RUs, ProtO-RU is built on the open-source srsRAN software stack, and it is fully programmable. We demonstrate that ProtO-RU integrates with the srsRAN and OpenAirInterface5G CU/DU stacks, supports both TDD and FDD duplexing modes, and interoperates with commercial 5G UEs. Our evaluation shows that ProtO-RU remains stable under sustained load with multiple UEs and delivers throughput comparable to Split-8 and commercial O-RUs. ProtO-RU opens up new opportunities for RU-level innovations and lowers the barrier of entry for end-to-end O-RAN research.

Problem

• Develops an open-source software-defined O-RAN Split-7.2 Radio Unit
• Integrates with existing CU/DU stacks and supports TDD/FDD modes
• Enables RU-level innovation and lowers O-RAN research barriers

Innovation

• Open source software-defined radio unit using SDRs
• Built on srsRAN stack, fully programmable and interoperable
• Supports TDD/FDD modes, stable throughput comparable to commercial