| .. This work is licensed under a Creative Commons Attribution 4.0 International License. |
| .. SPDX-License-Identifier: CC-BY-4.0 |
| .. Copyright (C) 2021-2023 Nordix Foundation |
| .. Copyright (C) 2024: OpenInfra Foundation Europe. All rights reserved. |
| |
| O-RAN A1 Interface |
| ~~~~~~~~~~~~~~~~~~ |
| |
| The O-RAN Alliance defines a new management interface "A1" for Radio Access Network (RAN) Management. This interface interconnects a new logical |
| "Non-RealTime RAN Intelligent Controller (Non-RT-RIC)" function in the Service Management & Orchestration (SMO) layer with a new logical "Near-RealTime |
| RAN Intelligent Controller (near-RT-RIC)" function in the RAN. This new A1 interface allows the Non-RT-RIC to provide Policy Guidance to the RAN (near-RT-RIC) |
| to steer its operation. These policies are defined by the O-RAN Alliance as "A1 Policies". The specifications for the A1 Interface, including A1 Policy support, |
| can be found on the O-RAN Alliance Specifications website. |
| |
| The A1 Policy functions are Orchestration and Automation functions for non-real-time intelligent management of RAN functions. The primary goal of the A1 Policy |
| functions is to support non-real-time radio resource management, higher layer procedure optimization, policy optimization in RAN, and providing guidance, |
| parameters, policies and AI/ML models to support the operation of Near-RealTime RIC (RAN Intelligent Controller) functions in the RAN to achieve |
| higher-level non-real-time objectives. |
| |
| A1 Policy functions form part of a Non-Realtime RIC as defined by O-RAN Alliance. Non-Realtime RIC functions include service and policy management, RAN analytics, |
| and model-training for the Near-RealTime RICs. The ONAP & O-RAN-SC A1 Policy work provides concepts, specifications, architecture and reference implementations |
| for A1 Policy support as defined and described in the O-RAN architecture. |
| |
| A1 Policy Management Service (from ONAP CCSDK) |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| The A1 Policy Management Service is a microservice which maintains a transient repository of: |
| |
| * All A1 policies instances in the network. Each policy is targeted to a near-RT-RIC instance and is owned by a 'service' (e.g., rApps or the NONRTRIC Dashboard). |
| * All near-RT-RICs in the network. |
| * All Policy types supported by each near-RT-RIC. |
| |
| The service provides : |
| |
| * Unified REST API for managing A1 Policies in all near-RT-RICs. |
| * Compliant with O-RAN R1 specification for A1-Policy Management (R1-AP v5.0, with additional features & fixes) |
| * Synchronized view of A1 Policy instances for each rAPP |
| * Synchronized view of A1 Policy instances in each near-RT-RIC |
| * Synchronized view of A1 Policy types supported by each near-RT-RIC |
| * Lookup service to find the near-RT-RIC to control resources in the RAN as defined in O1 (e.g. which near-RT-RIC should be accessed to control a certain CU or DU, which in turn controls a certain cell). |
| * Monitors all near-RT-RICs and maintains data consistency, e.g. recovery from near-RT-RIC restarts |
| * Support for different Southbound APIs to the near-RT-RICs (different versions of the A1-P and other similar APIs). |
| * HTTPS can be configured to use a supplied certificate/private key and to validate peers towards a list of trusted CAs/certs. |
| * HTTP proxy support for tunneling HTTP/HTTPS connections. |
| * Fine-grained access-control - with new optional callouts to an external auth function |
| * Fine-grained monitoring metrics, logging & call tracing can be configured |
| |
| See also A1 Policy Management Service in ONAP: `Wiki <https://wiki.onap.org/display/DW/O-RAN+A1+Policies+in+ONAP>`_, :doc:`Documentation<onapa1policymanagementservice:index>`. |
| |
| Implementation: |
| |
| * Implemented as a Java Spring Boot application. |
| |
| This product is a part of :doc:`NONRTRIC <nonrtric:index>`. |