A Modular O-RAN Testbed Based on SRS Open Source O-CU/O-DU and Massive Beams Modular O-RU

Jul 16, 2026

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A modular open radio access network (O-RAN) architecture is presented, combining a 5G Core with an open source central unit (O-CU) and distributed unit (O-DU) from Software Radio Systems (SRS) and a Massive Beams (MB) O-RAN radio unit (O-RU) for MODRAD-SC. The setup follows O-RAN split 7.2a, mapping higher-layer processing to OCUDU and low-PHY/RF handling to the O-RU, yielding a 5G gNodeB. An alternative software-defined configuration supports split 8 for non-real-time experiments. The platform enables full control of O-CU, O-DU, and O-RU, and supports optional hybrid digital-analog beamforming. It targets academia and industry through flexible modular experimentation and demonstrators.

LanguageEnglish

CategoryTechnology

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Pages7

Reading Time18 min

Introduction

Existing Open RAN and SDR Platforms

A Modular O-RAN Testbed Based on SRS Open Source O-CU/O-DU and Massive Beams Modular O-RU Fabian Gttsch∗ , Oriol Font-Bach†, Andreas Benzin∗ , Dennis Osterland∗ , Andre Puschmann†, Felix-Christopher Lutz∗ , Wilhelm Keusgen‡, Giuseppe Caire‡ ∗ Massive Beams, Berlin, Germany †SRS, Barcelona, Spain ‡Technical University Berlin, Berlin, Germany E-mail: {fabian.goettsch, andreas.benzin, dennis.osterland, [felix.lutz](felix.lutz}@massivebeams.com)[}](felix.lutz}@massivebeams.com)[@massivebeams.com](felix.lutz}@massivebeams.com) {oriol.font, [andre.puschmann](andre.puschmann}@srs.io)[}](andre.puschmann}@srs.io)[@srs.io](andre.puschmann}@srs.io) {wilhelm.keusgen, [caire](caire}@tu-berlin.de)[}](caire}@tu-berlin.de)[@tu-berlin.de](caire}@tu-berlin.de) arXiv :2607 .05 146v 1 [ cs .NI] 6 Jul 2026 Abstract—In this paper, we present a modular open radio access network (O-RAN) consisting of the 5G Core, a central (O-CU) and distributed unit (O-DU) by Software Radio Systems (SRS) and an O-RAN radio unit (O-RU), MODRAD-SC, by Massive Beams (MB). OCUDU provides an open source 5G-compliant OCU and O-DU solution developed by SRS, while MB’s radio unit is a fully O-RAN compliant category A O-RU. According to O-RAN split 7.2a, OCUDU performs higher layer functions up to the high physical (PHY) layer, while the O-RU handles low PHY and RF functions. This results in an O-RAN-compliant 5G gNodeB. In an alternative configuration, OCUDU and MODRAD-SC operate in a software-defined radio fashion corresponding to split 8, facilitating non-real-time experiments among others. In both cases, the system provides full control over O-CU, O-DU, and O-RU. In addition, we will discuss the possibility to attach an analog beamformer to the O-RU, enabling hybrid digital-analog beamforming. The flexibility and modularity offered by OCUDU and MODRAD-SC enable the practical realization of a multitude of applications, ranging from 5G demonstrators to pre-6G experiments. The system addresses the requirements of academia and industry and is well-suited as an easy-to-use platform for experimental and practical deployments. Index Terms—Open RAN, software-defined radio, hardware demonstration, testbed. I. INTRODUCTION In recent decades, wireless communication networks have increasingly become an indispensable part of everyday infrastructure. With every new generation of cellular or WLAN technology, parts of the standards have been changed to improve network performance. In parallel, huge progress in hardware and processing power have been achieved. The interaction of these advances has led to great improvements of data rates, latency, and coverage in wireless communication. These advancements have been obtained by theoretical and practical research, with some technologies and ideas developed in theory being deployed in practice many years or decades later, such as multiple-input-multiple-output (MIMO) wireless communication [1] . In order to bring ideas from theory into practice, test environments and demonstrators are required before large-scale implementation can take place. For this, readily accessible test equipment is essential. In particular, it is beneficial if the test equipment 1) can cover different technologies and use cases, 2) is easy to configure and use, and 3) is affordable for companies, universities and research institutes. For the architecture of next generation mobile communication systems such as 6G, Open Radio Access Network (ORAN) systems have emerged as a promising approach. O-RAN is a disaggregated RAN with open interfaces, midhaul and fronthaul between the network entities, where low physical (PHY) layer functions are handled by O-RAN Radio Units (O-RUs) and high PHY operations by O-RAN Distributed Units (O-DUs) [2] . This is an important difference to closed systems from previous mobile communication generations and enables mobile network operators (MNOs) to choose from amuch wider range of network components, such as DU

FAQs

What components make up the proposed modular O-RAN testbed?

The system integrates a 5G Core with an open source O-CU/O-DU (OCUDU) from SRS and a Massive Beams O-RU (MODRAD-SC). It forms an end-to-end 5G gNodeB where the radio components connect between the core network and user equipment.

How does O-RAN split 7.2a distribute functions between OCUDU and the O-RU?

Under split 7.2a, OCUDU performs higher-layer functions up to a high physical (PHY) layer, while the O-RU handles low-PHY and RF functions. This partitioning results in an O-RAN-compliant 5G gNodeB.

What changes in the alternative configuration and what experiments does it enable?

In an alternative configuration, OCUDU and MODRAD-SC run in a software-defined radio fashion corresponding to split 8. This facilitates non-real-time experiments and other flexible development scenarios.

Jul 16, 2026

Upload by Liam