High Level Architecture of O-RAN
The high level architecture of O-RAN includes three main areas: the Service Management and Orchestration (SMO) framework, O-RAN Functions and the O-Cloud.
The SMO is a collection of a variety of management services and provides a range of network management functions. The management functions may go beyond that of the RAN, but may include Core Management, Transport Management and End to End Slice Management. But in terms of RAN management the key operations include: support of the O1 interface to the O-RAN Network functions, the Non-Real Time RAN Intelligent Controller (RIC) for RAN optimization and O-Cloud management orchestration/workflow management.
The O-RAN Network Functions can either be Virtualized Network Functions (VNF) i.e. Virtual Machines (VMs) or Containers, sitting above the O-Cloud or Physical Network Functions (PNFs) using customized hardware. All O-RAN functions will use the O1 interface to the SMO.
The O-Cloud is a cloud computing platform consisting of a collection of physical infrastructure nodes that host the O-RAN functions. The O-RAN functions include the Near Real Time RIC, O-CU-CP, O-CU-UP, and O-DU.
There are four key interfaces namely O1, O2, A1 and optionally the Open Fronthaul M-Plane.