This section provides a brief overview of the O-RAN Alliance’s architecture and the positioning of VMware Telco Platform RAN in it.
Overview of O-RAN Architecture
The O-RAN Alliance’s architecture extends the 3GPP’s Open RAN architecture to further disaggregate the RAN. The O-RAN architecture not only splits the Distributed Unit (DU) of the 3GPP into a DU and a Radio Unit (RU) but also introduces the RAN Intelligent Controllers (RICs). These new components include some new interfaces.
The RICs are logical functions:
A non-real-time RIC, which is logically placed in the service management and orchestration function.
A near-real-time RIC
Both the RICs are virtualized or containerized components that control and optimize RAN elements and resources. The RICs access user context and sensitive data that requires extra protection and expose it to RAN microservices and applications developed by vendors.
The near-RT RIC can contain extensible microservices from third-party vendors to manage RAN resources for network functions. These microservices are called xApps. Similarly, the non-RT RIC can also contain applications that are called rApps.
O-Cloud: O-Cloud is a cloud computing platform that comprises a collection of physical infrastructure nodes. These nodes comply with O-RAN requirements to host O-RAN network functions (virtualized or containerized) including the Near-RT RIC, the CU control plane (O-CU-CP), the CU user plane (O-CU-UP), and the O-DU. The cloud platform supports components such as operating systems, container runtimes, and management and orchestration functions.
SMO: The Service Management and Orchestration (SMO) component manages the components and network functions of an open RAN.
The O-RAN architecture also includes the following network functions and applications:
O-CU-CP/UP: The centralized unit of the RAN and its control plane and user plane.
O-DU: The distributed unit of the RAN.
O-RU: The radio unit processes radio frequencies from antennas and other equipment.
O-eNB: The open-evolved NodeB refers to hardware supporting 4G RAN.
In the O-RAN architecture, the following interfaces are in use. Some of them are specified by the 3GPP:
A1 Interface between Non-RT RIC and Near-RT RIC to enable policy-driven guidance of Near-RT RIC applications and functions and to support AI/ML workflows
O1 Interface connecting the SMO to the Near-RT RIC, one or more O-CU-CPs, one or more O-CU-UPs, and one or more O-DUs
O2 Interface between the SMO and the O-Cloud
E2 Interface connecting the Near-RT RIC and one or more O-CU-CPs, one or more O-CU-UPs, one or more O-DUs, and one or more O-eNBs
Open Fronthaul CUS-Plane Interface between O-RU and O-DU
Open Fronthaul M-Plane Interface between O-RU and O-DU as well as between O-RU and SMO
By supporting virtualized and containerized network functions, these interfaces let you apply security controls with micro-segmentation and other techniques.
Some of these components, network functions, or interfaces are irrelevant to Telco Cloud Platform RAN because they are governed by vendors' network functions.
VMware Telco Cloud Platform RAN and the O-RAN Alliance Architecture
In the O-RAN architecture, VMware Telco Cloud Platform RAN or VMware Telco Cloud Automation™ delivers solutions for the cloud computing platform (O-Cloud), the service management and orchestration system (SMO), and the ability to connect these components with other clouds, and network function components including the CU, the DU, and the RICs. Telco Cloud Platform RAN runs DUs, CUs, and virtualized baseband functions by following the RAN performance and latency requirements. Telco Cloud Platform RAN automates the lifecycle management of Kubernetes clusters, RAN functions, and 5G services. It also optimizes the placement of DUs and CUs through programmable resource provisioning.
Telco Cloud Platform RAN includes a security-hardened Linux host called Photon OS that is optimized for running containers on VMware vSphere®.
VMware Telco Cloud Service Assurance™ and VMware RIC™ can be added optionally to a RAN stack to supply subsets of SMO.
The following diagram illustrates the O-RAN logical architecture and interfaces with VMware Telco Cloud Platform RAN that runs the CU, DU, and other RAN components from a vendor.
