Open Source CU/DU Integration for 5G Small Cells

RANsemi Limited and TechPhosis Private Limited have integrated the Linux Foundation's open-source 5G OCUDU software stack with the RANsemi RNS802 baseband PHY. Utilizing the Small Cell Forum (SCF) FAPI interface, this collaboration establishes a framework for deploying low-SWaP (size, weight, and power) 5G integrated small cells for private and mission-critical networks.

Baseband Integration and Protocol Architecture
The integration utilizes the Small Cell Forum (SCF) FAPI standard to connect the open-source CU/DU (Centralized Unit/Distributed Unit) stack with the optimized commercial physical layer (PHY). This architectural approach demonstrates that open-source software, conventionally associated with disaggregated O-RAN environments, can be deployed within compact, integrated small cell architectures without requiring proprietary middleware. The TechPhosis integration bridges the gap between open-source community code and commercially deployable 5G infrastructure, providing functional L2/L3 RAN processing.

Scalability and Deployment Flexibility
Engineered to support multiple network topologies, the software architecture provides a pathway for both integrated and disaggregated 5G environments. Beyond integrated small cells, the OCUDU-based implementation can be extended to O-RAN 7.2 split architectures utilizing the RANsemi RNS805 O-RU System-on-Chip (SoC). This cross-platform compatibility allows network developers to maintain a single, consistent software codebase across localized private networks and distributed commercial infrastructure deployments.

Additional Context: This section details technical specifications not included in the original announcement
In 5G Radio Access Network (RAN) architectures, baseband processing is divided into the Centralized Unit (CU), Distributed Unit (DU), and Radio Unit (RU). The FAPI (Functional Application Platform Interface) standard, developed by the Small Cell Forum, provides a standardized API between the MAC (Medium Access Control) layer within the DU and the physical layer (PHY). This standardized boundary is critical for hardware abstraction; it allows network operators to seamlessly swap an open-source L2/L3 software stack (like the Linux Foundation's OCUDU) with different silicon-level PHY implementations without rewriting the core baseband processing logic. While the O-RAN Alliance's Split 7.2x defines the fronthaul interface between the DU and the RU over Ethernet, utilizing FAPI enables developers to consolidate the CU, DU, and RU into a single physical enclosure (an integrated small cell) optimized for low-latency, edge-deployed private 5G networks.

Edited by Lekshman Ramdas, Induportals editor – adapted by AI.

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