Bhanu Chandra is a Senior Member of Technical Staff at Aarna Networks, a SaaS solutions provider that offers zero-touch edge and 5G services orchestration and management at scale. Prior to Aarna, he was Principal Engineer at Western Digital, a Member of Technical Staff at Aruba Networks, a Lead Engineer at NetScout systems, and an analyst at Cognizant Technologies. Bhanu holds M.Tech degree from Jawaharlal Nehru Technological University. He lives in Bangalore, India.
In this three part blog series, I am going to talk about O-RAN architecture with a little extra emphasis on the Service Management & Orchestration component, the NONRTRIC, and finally some NONRTRIC use cases. Today we'll cover the first topic.
The O-RAN specification allows service providers to speed up 5G network development through its standardized architecture. It minimizes proprietary hardware dependency and makes the network more accessible to a broader range of designers.
The O-RAN alliance architecture principles are:
Radio area network (RAN) virtualization, open interfaces, and AI-capable RAN
Disaggregation of RAN element deployment and leveraging multi vendor solutions
Minimization of proprietary hardware and a push toward merchant silicon and off-the-shelf hardware
Interfaces and APIs to drive "standards to adopt them as appropriate" and explore "open source where appropriate"
Service Management & Orchestrator (SMO): The component that oversees all the orchestration aspects, management and automation of RAN elements. It supports O1, A1 and O2 interfaces.
Non-RT RIC (non-real-time RAN Intelligent Controller): A logical function that enables non-real-time control and optimization of RAN elements and resources, AI/ML workflow including model training and updates, and policy-based guidance of applications/features in near-RT RIC.
Near-RT RIC (near-real-time RAN Intelligent Controller): A logical function that enables near-real-time control and optimization of O-RAN elements and resources via fine-grained data collection and actions over the E2 interface. It includes interpretation and enforcement of policies from Non-RT RIC. and supports enrichment information to optimize control function.
O-CU (O-RAN Central Unit): A logical node hosting RRC, SDAP and PDCP protocols. O-CU includes two sub-components O-CU-CP (O-RAN Central Unit – Control Plane) and O-CU-UP (O-RAN Central Unit – User Plane).
O-DU (O-RAN Distributed Unit): A logical node hosting RLC/MAC/High-PHY layers based on a lower layer functional split.
O-RU (O-RAN Radio Unit): A logical node hosting Low-PHY layer and RF processing based on a lower layer functional split.
O-RAN SMO Interfaces
The key O-RAN SMO interfaces are:
O1: Interface between management entities in Service Management and Orchestration Framework and O-RAN managed elements, for operation and management, by which FCAPS management, software management, and file management shall be achieved.
O2 (previously O1*): Interface between Service Management and Orchestration Framework and Infrastructure Management Framework supporting O-RAN virtual network functions.
A1: Interface between non-RT RIC and near-RT RIC. Over this interface non-RT RIC performs policy management, enrichment information and AI/ML model updates on the near-RT RIC.
In the next post we will see the various requirements and current limitations, and how the O-RAN architecture — especially the non-RT RIC — optimizes the 5G network.