O-RAN ALLIANCE Summit - Accelerating Open RAN Adoption
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O-RAN ALLIANCE Introduces 40 New Specifications Released Since November 2021

O-RAN ALLIANCE has released another set of technical specifications for open and intelligent RAN published since November 2021. This batch of specs, together with the batch published in July 2021, complete the O-RAN Release 002, the first O-RAN Release focusing on enabling Open Intelligence. To access the O-RAN specifications, please visit our website.

This batch include 4 new titles comprising:

  • O-RAN R1 interface: General Aspects and Principles v1.0
  • O-RAN A1 interface: Test Specification v1.0
  • O-RAN Acceleration Abstraction Layer High-PHY Profiles v1.0
  • O-RAN Security Tests Specifications v1.0

Another 36 technical documents bring extensions and new features to the existing specifications. A brief overview of all 40 specifications is provided below.

WG1: Use Cases and Overall Architecture Work Group

4 specifications published since November 2021:

O-RAN Architecture Description v6.0

The O-RAN Architecture Description document specifies the overall architecture of O-RAN. It describes all the O-RAN functions and relevant interfaces that connect these functions. This version clarifies how R1 interface enables rApps to obtain information and trigger actions through the SMO interfaces towards O-RAN functions. It includes the ‘Open FH M-Plane’ interface (between SMO and O-RU) to the functional architecture of the Non-RT RIC. A section on the ‘UE Associated Identifier’ for correlating UE identities across all O-RAN logical functions has been added. It introduces the ‘O-Cloud Notification’ interface to enable O-RAN functions to receive critical information from the cloud infrastructure. The O-RAN security architecture consisting of ‘Threat Analysis’, ‘Attach Surfaces’, and ‘Security Protocols’ is another notable feature of this version.

O-RAN Use Cases Analysis Report v7.0

This document describes potential O-RAN use cases at a very high level, emphasizing how the use case is enabled by the O-RAN architecture along with basic input data expectations and resulting actions. This version includes addition of a new use case (“Integrated SON Function”) and updates to NSSI resource optimization use case.

O-RAN Use Cases Detailed Specification v7.0

This document describes selected O-RAN use cases in further details to facilitate relevant O-RAN Work Groups to define requirements for associated O-RAN functions and interfaces. This version includes updates to NSSI resource optimization use case.

O-RAN Slicing Architecture v6.0

This document describes O-RAN slicing related use cases, requirements, and architecture. Along with requirements and a reference slicing architecture, slicing related impact to O-RAN functions and interfaces is also captured. This version includes updates to NSSI resource optimization use case and a new Annex section for slicing terminology awareness.

WG2: The Non-real-time RAN Intelligent Controller and A1 Interface Work Group

3 specifications published since November 2021:

O-RAN R1 interface: General Aspects and Principles v1.0

The R1 GAP Specification has summarized the R1 Interface Specification Objectives and Specified the Principles and procedures for:

  • Service Management and Exposure service involving Service Producer and Service Consumer roles
  • Data Management and Exposure service procedures and principles involving the Data Producers and Data Consumer roles
  • Procedure details of Network information service, Fault management service and Performance management service that are exposed as O1-Releated functions to rApp’s via R1 Interface

O-RAN A1 interface: Test Specification v1.0

This initial version of the A1 Test Specification includes conformance tests for both the Non-Real-Time RIC and the Near-Real-Time RIC for the policy related services on the A1 interface.

O-RAN Non-RT RIC & A1 Interface: Use Cases and Requirements v5.0

This document describes O-RAN Non-RT RIC use cases in detail including the required datasets, the workflows, and the interactions within and outside of Non-RT RIC with other O-RAN components. As a result of the use case analysis, this specification captures the requirements imposed by these use cases on the Non-RT RIC architecture, A1 and R1 interfaces as well. This version includes the addition of NSSI resource optimization use case and updates to RAN Slice SLA assurance use case.

WG3: The Near-Real-Time RAN Intelligent Controller and E2 Interface Work Group

6 specifications published since November 2021:

O-RAN Near-Real-Time RAN Intelligent Controller Near-RT RIC Architecture v2.01

This specification describes the functional architecture of O-RAN Near-Real-Time RAN Intelligent Controller (Near-RT RIC), and the Stage-2 designs of Near-RT RIC APIs between Near-RT RIC platform and xApps. This version introduces a new internal function “xApp repository function”, additional Near-RT RIC API designs, and revisions related to the management and orchestration of xApps.

O-RAN Near-Real-Time RAN Intelligent Controller Architecture & E2 General Aspects and Principles v2.01
O-RAN Near-Real-Time RAN Intelligent Controller, E2 Application Protocol (E2AP) v2.01
O-RAN Near-Real-Time RAN Intelligent Controller E2 Service Model (E2SM) v2.01

A set of three E2 specifications present corrections and minor enhancements to their corresponding v2.0. Support of E2 removal, clarifications on multiple TNLA handling, and definition of UE identity over the E2 interface are provided.

O-RAN Near-Real-Time RAN Intelligent Controller E2 Service Model (E2SM) KPM v2.01

The newer version of E2SM-KPM includes additional network measurements related to slicing and new report styles for group of UEs, compared to its v2.0.

O-RAN Near-Real-Time RAN Intelligent Controller E2 Service Model (E2SM), RAN Control v1.01

The newer version of E2SM-RC contains clarifications and small corrections to its v1.0.


WG4: The Open Fronthaul Interfaces Work Group

4 specifications published since November 2021:

O-RAN Control, User and Synchronization Plane Specification v8.0

This specification defines the Control Plane, User Plane and Synchronization Plane of the Open Fronthaul Interface. Version 8.0 contains main changes in the following areas:

  • New features for C-Plane/U-Plane or enhancements for fronthaul efficiency
  • Updates to the spec for alignment with ETSI submission
  • Clarifications

O-RAN Management Plane Specification - YANG Models v7.01 - Essential correction

This spec brings essential upgrade of YANG models for Management Plane specification in v7.0.

O-RAN Management Plane Specification v8.0

This document describes O-RAN Open Fronthaul M-Plane Specification, which defines the Management Plane of the Open Fronthaul Interface as well as the associated YANG models. This version contains main changes in the following areas:

  • Addition of new functionalities:
  • Introduction of alarm-type and alignment with 3GPP 28.532
  • Enable IANA Private Enterprise Number to be used as Vendor Code in software management
  • Boundary Clock function
  • Capability for supporting multi-cell operation
  • Compression support for Section Type 6
  • Mandatory support of TLS, PKIX, and FTPES
  • Supporting multiple transport session types simultaneously
  • Shared cell enhancements introducing t-combine-net and tx-duration
  • Renumbering of specification to align with ETSI PAS Process
  • Bug fixes and clarifications to v7.0

O-RAN Fronthaul Interoperability Test Specification (IOT) v6.0

This document describes O-RAN Open Fronthaul IOT Specification, which defines tests to validate the ability for O-DU and O-RU equipment to operate together using the Open Fronthaul Interface. This version delivers:

  • New IOT profile test configurations added for IPv6 and TLS.
  • Updated IOT profiles and profile test configurations
  1. New mMIMO IOT profile timing parameters ERI-0030
  2. Update of NR TDD IOT profile 1 CHM-0003
  3. Update of NR TDD profile 2 DCM-0015
  4. Update of NR FDD profile4 DCM-0016
  • Correction of IQ compression field for mMIMO IOT profiles MAV-0027

WG5: The Open F1/W1/E1/X2/Xn Interface Work Group

5 specifications published since November 2021:

O-RAN Interoperability Test Specification (IOT) v3.0

The scope of WG5 IOT spec is to specify interoperability tests for RAN Node from different vendors implemented in accordance with the WG5 C-plane and U-plane profiles.

This version of the IOT spec focuses on:

  • X2 interoperability testing where Devices under Tests (DUTs) are eNB and en-gNB
  • F1 interoperability testing where DUTs are en-gNB consisting of the gNB-CU and gNB-DU
  • Xn interoperability testing where DUTs are gNBs

Main Updates compared to v2.0 include:

  • 35 new test cases for use cases specified in WG5 profiles
  • Maintenance of the existing test cases including editorial corrections

O-RAN NR U-plane profile v5.0

The scope of U-Plane profile spec is to further clarify the expected behavior (still within the scope of the 3GPP specifications) of each RAN node, e.g. usage of IEs for each use case, general behavior of each node, etc. U-Plane profile specification contains profiles of X2/F1/Xn U-Plane procedure for EN-DC use cases, NR-SA use cases and NR-DC use cases.

Main Updates compared to v4.0 include 3GPP baseline version uplifted to Rel-16.

O-RAN NR C-plane profile v6.0

The scope of C-Plane profile spec is to further clarify the expected behavior (still within the scope of the 3GPP specifications) of each RAN node, e.g. usage of IEs for each use case, general behavior of each node, etc. C-Plane profile specification contains profiles of X2/F1/Xn C-Plane procedure for EN-DC use cases, NR-SA use cases and NR-DC use cases.

Main Updates compared to v5.0 include:

  • IAB use cases were newly specified in v06 as main new use cases
  • 3GPP baseline version was uplifted to Rel-16
  • Corrections and clarifications

O-RAN O1 Interface specification for O-DU v3.0

The scope of O-DU O1 Interface specification is to specify the interface that links O-DU to the Service Management and Orchestration (SMO) framework. It is focused on O-DU management operations, performance counters, fault supervision, software management, synchronization management, and configuration parameters for O-DU. Compared to v2.0, this version includes:

  • PM counters for Slicing SLA Management
  • Alignment with 3GPP SA5 on RRM Policy, and with WG10 O1 interface specification
  • Holdover Sync state updated, and other editorial updates

O-RAN O1 Interface specification for O-CU-UP and O-CU-CP v2.0

The scope of O-CU O1 Interface specification is to specify the interface that links O-CU-CP and O-CU-UP to the Service Management and Orchestration (SMO) framework. It is focused on O-CU management operations, performance counters, fault supervision, software management, and configuration parameters for O-CU. Compared to v1.0, this version includes:

  • PM counters for Slicing SLA Management
  • PM counters naming updated, and other editorial updates

WG6: The Cloudification and Orchestration Work Group

5 specifications published since November 2021:

O-RAN O2 Interface General Aspects and Principles v1.02

This document specifies the general aspects and principles associated with the O2 interface. This version introduces the O-Cloud Provisioning concepts, the O-Cloud Performance concepts, and it also provides further clarification about the O2 DMS interface, i.e. an O-Cloud might have its own specific O2dms service API profile.

O-RAN Acceleration Abstraction Layer High-PHY Profiles v1.0

This specification details the AAL specification for inline accelerators supporting the High-PHY acceleration profiles for all uplink and downlink channels. It contains the description of the interface, information models and requirements to implement an AALI, for the AAL_DOWNLINK_High-PHY and AAL_UPLINK_High-PHY profiles.

O-RAN Cloudification and Orchestration Use Cases and Requirements for O-RAN Virtualized RAN v3.0

This document specifies use cases and associated requirements for the management and orchestration of O-RAN virtualized RAN. This version is retitled “Cloudification and Orchestration Use Cases” and incorporates use case additions to support Functional Status Query, Fault, Performance and VLAN Management Use Cases.

O-RAN Acceleration Abstraction Layer General Aspects and Principles v2.0

O-RAN AAL enables decoupling of RAN software from hardware by defining abstract interfaces for accelerated RAN functions to allow a RAN software implementation to work with different accelerator implementations. The AAL GA&P defines the high-level architecture and accelerator profile definitions for the AAL. This version of the document adds updates to support inline High-PHY profiles including AALI definitions, general interface principles, and the introduction of aggregated Downlink and Uplink High-PHY profiles.

O-RAN O2ims Interface Specification v1.01

This specification outlines the infrastructure management services of the O2 interface. This version brings clarification about the attributes of the O-Cloud, and it synchronizes the Infrastructure Inventory figure with the descriptions in the related table.

WG8: Stack Reference Design Work Group

2 specifications published since November 2021:

O-RAN Stack Interoperability Test Specification v3.0

The O-RAN Stack Interoperability Test Specification provides interoperability test cases of O-CU and O-DU for end to end call flows. This version contains the following updates:

  • O1 interface test cases
  • Beam management test cases
  • Timing profiles (C1 to C3)

O-RAN Base Station O-DU and O-CU Software Architecture and APIs v5.0

The O-RAN Base Station O-CU and O-DU Architecture and APIs specification provides the reference architecture, design and APIs for O-CU and O-DU implementation. The specification details the functional block of O-CU and O-DU, including messages across L1, L2 and L3 layers and call flows. This version adds the following key updates:

  • RAN slicing feature configuration/functionalities
  • Updated mobility section 8.2.2 Inter O-DU Handover within an O-CU
  • O-DU Timing Synchronization
  • Accelerator Abstraction Layer (AAL) description

WG9: Open X-haul Transport Work Group

3 specifications published since November 2021:

O-RAN WDM-based Fronthaul Transport v2.0

This document describes best practices for O-RAN fronthaul transport based on WDM technology. This version contains the following enhancements:

  • Link budget for MWDM/DWDM systems beyond 10km
  • Enhancements of power consumption of optical transceivers
  • Summary of optical transceiver variants for Xhaul
  • Single and duplex fiber solutions for passive WDM systems

O-RAN Management interfaces for Transport Network Elements v3.0

The document is intended to describe best practices for O-RAN transport Network Element (TNE) management interfaces. This version adds:

  • Grandmaster clock for Synchronization
  • WDM fronthaul interface requirements for passive-passive and passive-active
  • Clarification of security requirements
  • Introduction of network slicing use case

O-RAN Synchronization Architectures and Solutions Specification v2.0

The document describes best practices for O-RAN Architecture and Solution for X-haul timing and synchronization. This version adds content for:

  • Timing/synchronization redundancy and resiliency
  • Ring topology
  • Use cases for lls-C2 and lls-C4
  • PON systems

WG10: OAM Work Group

3 specifications published since November 2021:

O-RAN Operations and Maintenance Architecture v6.0

The O-RAN OAM Architecture identifies management services, managed elements, functions and applications supported in O-RAN, including the interworking between SMO and O-RAN O-Cloud management components. Requirements are derived from end-to-end OAM use cases, including the initial provisioning of O-RAN service across VNFs and PNFs and the collection of measurement data. This version includes:

  • Basic Architecture updates to align better with the O-RAN Architecture Description
  • Updates to references and corrections to the end-to-end use case

O-RAN Operations and Maintenance Interface Specification v6.0

The O1 interface defines management services supported by O-RAN managed elements and provides an interface between these managed elements and the SMO. This version includes:

  • Introduction of the PNF Reset Management Service that introduces the capability for the SMO to request that a PNF resets
  • Performance Assurance updates and corrections
  • Fault Management support for the notifyAlarmListRebuilt notification
  • Introduction of the Cloudified NF Registration Management Service to allow an instantiated Cloudified NF to register with the SMO
  • Notification Format update to support both 3GPP-specified and O-RAN-specified notifications

O-RAN Information Model and Data Models Specification v2.0

This version of Information Model and Data Models spec includes:

  • Extension of YANG style guide with respect to O1 (3GPP) aligned models’ creation.
  • Addition of a link to WG10 repository
  • Further editorial fixes

TIFG: Test and Integration Focus Group

1 specifications published since November 2021:

O-RAN Certification and Badging Processes and Procedures v3.0

This document describes the certification and badging processes and associated detail technical procedures that Open Testing and Integration Centre (OTIC) and various other testing entities should adopt. This version brings forth the following:

  • Clarification in Chapter 2 on what entity can issue certificates and badges with O-RAN logos
  • Removing the sharing mechanism in Chapter 3 related to self-certification by vendors, individual operators, and 3rd party testing houses/labs
  • Adding in Chapter 3 the requirement on universal machine-readable format in test data sharing
  • Making test case 2.2.4.6 in Chapter 5 mandatory
  • Modifying the wording in Section 5.2.1 to be more concise and refer to Fronthaul IOT test specification clearly
  • Revising Figure 3.2-1 and Table 4.2-1 to sync up with the latest reference documents
  • In the companion test report template, making the following changes
  • Adding tab for O-DU Conformance
  • Adding new test cases defined in WG4 CONF v04.00 to “FH O-RU Conformance” tab
  • Editorial corrections throughout the “FH O-RU Conformance” tab

SFG: Security Focus Group

4 specifications published since November 2021:

O-RAN Security Requirements Specifications v2.0

This document specifies the Security Requirements per O-RAN Interface and per O-RAN component and adds transversal requirements and Software Bill of Material (SBOM) guidelines. This version includes:

  • Confidentiality, Integrity, Replay protection and Authentication are required for A1, O1, O2, E2 interfaces
  • Least Privilege Access Control on O1 interface is enforced with Network configuration Access Control Model (NACM) requirements
  • Authentication and Authorization based on IEEE 802.1x Port based Network Access Control is required to control network access in point-to-point LAN segments within the Fronthaul interface
  • Transversal requirements on Networks Protocols and Services requires unused protocols to be disabled and common transport protocols used in O-RAN system should be able to handle unexpected inputs without functional compromise. O-RAN components should also withstand network transport protocol based volumetric DDoS attacks. Known vulnerabilities in the OS and applications of an O-RAN component shall be clearly identified. Password configurations on O-RAN components shall be examined to validate secure password policies are supported and enforced.
  • Software Bill Of Material (SBOM) should be provided with every O-RAN software delivery according to NTIA guidance. SBOM is an industry best practice part of secure Software Development Life Cycle (SDLC) that enhances the understanding of the software supply chain and provides transparency into the use of open-source software having known vulnerabilities or contributions from individuals or companies in adversarial nations. SBOM must be protected in Confidentiality, Integrity, Authenticity with restricted Access Control.

O-RAN Security Protocols Specifications v3.0

This document specifies security protocols to be used for O-RAN compliant implementation. It captures implementation requirements for SSH, IPSec, DTLS, TLS 1.2, TLS 1.3 and NETCONF support over secure Transport. This version adds mandatory support for TLS 1.3.

O-RAN Security Tests Specifications v1.0

This document provides description of the Security Tests which validate security functions, configurations and security protocols requirements. It contains sets of tests to validate proper implementations of security protocols as defined in the O-RAN Security Protocols Specifications (SSH, TLS, DTLS, IPSec). Tests for O-RAN components related to transversal requirements defined in O-RAN Security Requirements specification are also specified: Service Enumeration, Password-based Authentication protection against brute-force, Unauthorized password reset, Secure password policy enforcement, Robustness against volumetric DDoS attacks. Security evaluation of robustness of OS and Applications of O-RAN components are also specified with system vulnerability scanning.

O-RAN Security Threat Modeling and Remediation Analysis v2.01

This document specifies the O-RAN Security Threat Modeling and Remediation Analysis. It identifies assets to be protected, analyzes the O-RAN components for vulnerabilities, examines potential threats associated with those vulnerabilities and their mapping to specific O-RAN identified assets. It provides security principles, which stakeholders should address when building a secure end-to-end O-RAN system. It brings a risk assessment based on ISO 27005 standard that aims to assess the criticality of threats based on their potential impacts. This version adds further details and new threats related to the Fronthaul Control and Synchronization planes interface.


Chih-Lin I and

Sachin Katti