• The O-RAN architecture introduces a new management interface - “A1 interface” - between the network management system and the radio access network (RAN)

  • A1-AP (Application Protocol) specified by O-RAN Alliance WG2

• A1 interface enables vendor-agnostic policy-based guidance (“A1 Policies”) to be sent to underlying RAN elements from the management system.

  • “A1-EI” will also support transmission of enrichment information from the management platform to the RAN elements (Still being defined – currently out of scope)

  • “A1-ML/AI” may also assist with ML Model management in the RAN (Still being defined – currently out of scope)

• The A1 interface connects Non-RealTime-RIC logical function in OAM/SMO layer with the Near-RealTime-RIC logical function in the RAN.

A1 in O-RAN Architecture for Disaggregated RAN

Open

A1 in O-RAN Architecture

• From ORAN-WG1 Architecture Description - v01.00.00 - https://www.o-ran.org/specifications

A1 Adapter in Frankfurt

• Implemented as an SDNC/CCSDK extension to terminate & expose A1 interface

• https://lf-onap.atlassian.net/wiki/display/DW/A1+Adapter+in+ONAP

• Developed for Release Requirement (REQ-38): 5G / ORAN & 3GPP Standards Harmonization

• Can be used by other ONAP functions to perform A1 Policy Operations over A1 Interface

• Provides DMaaP northbound interface, and REST (A1) southbound interface

Enhancements for Guilin Release

• Add additional support for standardized A1 protocol (O-RAN A1-AP v1.1)

  • Current (Frankfurt) supports only O-RAN-SC’s (draft) non-spec version of A1 Application Protocol

  • Will add support for upcoming A1 standard spec evolution

  • Will add support for multiple versions for different A1 connections

• Managing A1 Policies

  • Operations:

    • Query A1 Policy Types in near-RT-RICs

    • Create/Query/Update/Delete A1 Policy Instances in near-RT-RICs

    • Query Status for A1 Policy Instances

  • Maintain transient cache of RAN’s A1 Policy information

    • Support RAN-wide view of A1 Policy information

    • Streamline A1 traffic

    • Enable (optional) re-synchronization after inconsistencies / near-RT-RIC restarts

• Add support for multiple near-RT-RICs (with multi-version support)

• Unified REST & DMaaP NBI

• Add support for TLS/HTTPS REST for southbound A1 interfaces (and NBIs)

  • Leverage existing ONAP cert management approaches

• Converge ONAP & O-RAN-SC A1 Adapter/Controller functions in ONAP SDNC/CCSDK

  • Proposed functionality is currently available as 2 functions in O-RAN-SC

  • Basic A1 Adapter is an ODL extension & Policy Management is a separate microservice

A1 Policies - Northbound Interface (REST & DMaaP) Proposed

• See