O-RAN ALLIANCE Summit - Accelerating Open RAN Adoption
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20 New O-RAN Specifications Have Been Released Since June 2020

By Chih-Lin I and Sachin Katti.

As O-RAN ALLIANCE’s technical specification effort grows with healthy momentum expanding RAN standards with open interfaces and intelligent RAN functions, its approved specifications are available to the general public upon agreement to the O-RAN ALLIANCE Adopter License.

O-RAN specifications published in 2nd half of 2020 introduce the initial version of O2 interface general aspects and principles, and two sets of the HW reference design for the indoor picocells in 7-2 and 8.0 split, respectively. An initial end-to-end system testing framework and the Criteria and Guidelines for the Open Testing and Integration Centres (OTIC) as the global platform for testing and integration of O-RAN based network equipment are also delivered.

Another 15 newly released specifications bring updates to existing O-RAN standards, enriching them with new functions or updated features according to the O-RAN Architecture.

WG1: Use Cases and Overall Architecture Workgroup

O-RAN Architecture Description v2.0

The Architecture Description document specifies the overall architecture of O-RAN. It describes all of the O-RAN functions and relevant interfaces that connect these functions. Version 2.0 carries forth the architecture evolution principle. It introduces seven new implementation options by bundling various combination of O-RAN functions. It clarifies O-RAN’s position on multiple Lower Layer Split (LLS) options by establishing Open Fronthaul (Option 7-2x) as the interface between O-DU and O-RU. Other LLS options may be considered for reference designs either through industry open standards (e.g., the Small Cell Forum for Option 6) or in O-RAN white-box hardware specifications (e.g., Option 8).

Use Cases Analysis Report v3.0

This document describes how potential O-RAN use cases are enabled by the O-RAN architecture along with respective input data expectations and resulting actions. Version 3.0 includes four new use cases (Multi-vendor Slices, Dynamic Spectrum Sharing, Long-term NSSI Optimization, Local Positioning) and enhancements to two of the existing use cases (Massive MIMO, Traffic Steering).

Use Cases Detailed Specification v3.0

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. Version 3.0 includes the detailed definition of a new use case, RAN Slice SLA Assurance, and enhancements to and existing use case, Traffic Steering.

Slicing Architecture v2.0

This document provides the O-RAN slicing related requirements and a reference slicing architecture. Slicing related impacts to O-RAN functions and interfaces are also captured. Version 2.0 includes the detailed definition of slice management and provisioning along with related requirements, and the consideration of two new slicing use cases (Multi-vendor Slices, Long-term NSSI Optimization).

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

A1 interface: General Aspects and Principles v2.0

In addition to enhancements to the A1 policy aspects, version 2.0 of the document defines the concepts for A1 Enrichment Information, which will be specified in the next version (v3.0) of the A1 Application Protocol.

A1 interface: Application Protocol v2.0

In version 2.0, the A1 Policy definition is enhanced with the addition of Policy Types. The rules for encoding data types on the interface have been enhanced to ensure interoperability.

WG3: The Near-real-time RAN Intelligent Controller and E2 Interface Workgroup

Near-Real-time RAN Intelligent Controller (Near-RT RIC) Architecture & E2 General Aspects and Principles (E2GAP) v1.1
Near-Real-time RAN Intelligent Controller (Near-RT RIC) E2 Application Protocol (E2AP) v1.1

These two document describes the general architecture of Near-RT RIC and the main functions and procedures supported over the E2 interface, and the E2 application protocol of Near-RT RIC.Version 1.1 of introduce minor enhancements to existing specifications and align those with other relevant O-RAN specifications. The enhancements address: E2 Node Configuration Update to provide basic RAN configuration to the Near-RT RIC for each E2 Node; TNL for E2 for scalability, allowing to use multiple SCTP connections; and OID in E2 Application Protocol to assist E2 Service Model decoding.

O-RAN ALLIANCE Logical Architecture

WG4: The Open Fronthaul Interfaces Workgroup

Control, User and Synchronization Plane Specification v4.0
Management Plane Specification v4.0

The Open Fronthaul Interface CUS-Plane and M-Plane specifications version 4.0 include several interface efficiency enhancements, including M-Plane definition of periodic channels such as PRACH and SRS, as well as the TDD pattern. Also, several synchronization enhancements were made to better align to ITU-T specifications, and a dynamic range optimization feature was added. In addition, several corrections and clarifications were made to the material. Finally, the objectional word “slave” was replaced with “subordinate”.

WG5: The Open F1/W1/E1/X2/Xn Interface Workgroup

NR C-plane profile v3.0

In version 3.0, the specification was extended to encompass the NR-SA case. It also contains profiles of X2/F1/Xn C-Plane procedure for new and updated EN-DC use cases as well as new NR-SA use cases.

NR U-plane profile v3.0

In v3.0, the specification was extended to encompass the NR-SA case. Minor updates/corrections on contents in v2.0 were done.

WG6: The Cloudification and Orchestration Workgroup

O2 General Aspects and Principles v1.0

This document introduces the general aspects and principles for the O2 interface. The document studies an initial set of functions conveyed over the O2 interface, including management functions, procedures and operations; it also identifies appropriate existing standards and open source solutions that may be leveraged.

Cloud Architecture and Deployment Scenarios for O-RAN Virtualized RAN v2.1

This update of the Cloud Architecture and Deployment Scenarios technical report introduces two O-Cloud functionalities, namely the O-Cloud Switch Fabric and the O-Cloud Notification Framework. In addition, the scenario B is extended to support E-UTRA network functions.

Cloud Platform Reference Design for Deployment Scenario B v1.1

Version 1.1 updates the O-Cloud Reference Design for deployment scenario B, specifically it includes examples using  FPGA and GPU as accelerators. It also covers the CRI support for containers.

WG7: The White-box Hardware Workgroup

Hardware Reference Design Specification for Indoor Picocell FR1 with Split Architecture Option 7-2 v1.0

This is the initial version of O-RAN Hardware Reference Design Specification for Indoor Picocell FR1 with Split Architecture Option 7-2.  It describes a white box hardware reference design example for indoor deployments. In this version you will find:

  • The reference designs for O-CU, O-DU7-2, O-RU7-2 and FHGW7-2/FHGW7-2 → 8.  FHGW7-2 → 8 will be used for Base stations having requirements to change their fronthaul interfaces from a split option from 7-2 to a split option 8.
  • This version of the specification is compliant to  Indoor Picocell Hardware Architecture and Requirement (FR1 Only) v1.0.

Hardware Reference Design Specification for Indoor Picocell FR1 with Split Architecture Option 8 v1.0

This is the O-RAN Hardware Reference Design Specification for Indoor Picocell FR1 with Split Architecture Option 8.  It describes a white box hardware reference design example for indoor deployments. In this version you will find:

  • The reference designs for O-CU, O-DU8, O-RU8 and FHGW8.  FHGW8 will only be used for interfacing O-DU8 with an O-RU8 stations.
  • A vendor specific CPRI Interface (ANNEX 2) which includes User Plane data and Control and Management Plane transport mechanisms is provided. This specification supports the Option 8 split fronthaul connection between O-DU8 and O-RU8 (s). For indoor Picocell deployment case, it also supports FHGW8 between O-DU8 and O-RU8.
  • This version of the specification is compliant to  Indoor Picocell Hardware Architecture and Requirement (FR1 Only) v1.0.

Deployment Scenarios and Base Station Classes v2.0

The main objective of this document is to aid in development of base station HW architecture and requirements specification, and consequently, the HW reference design specification for all white boxes based on deployment scenarios requested by operators.  Major additions in this version include:

  • Outdoor Macrocell deployment scenario and its BS classes requested by DISH, and Verizon
  • More frequency bands as requested by T-Mobile, DISH and Verizon

TIFG: Test and Integration Focus Workgroup

Criteria and Guidelines of Open Testing and Integration Centre v1.0

This specification describes the essential criteria and guiding principles to qualify an Open Testing and Integration Centre (OTIC) from the process, organization, facility space and technical perspectives. This version defines the organizational roles in the OTIC and the minimum requirements of the OTIC physical lab architecture and layout. It provides the basic guidelines on the participation agreements used in OTIC and describes the qualification and disqualification processes of the OTIC.

End-to-End System Testing Framework v1.0

This specification defines the End to End (E2E) testing framework for comprehensive E2E testing and validation of the Open RAN (O-RAN) Systems ensuring robust interoperability and operation with high performance as intended in real-world deployments. This version introduces the concept of O-RAN Deployment Blueprints and defines the methodology for holistic testing and evaluation of the O-RAN Deployment Blueprints. The purpose is to ensure that these Blueprints can be robustly tested and optimized, with consistent high quality and performance in a deterministic and repeatable manner across the entire technology lifecycle.

Chih-Lin I
(China Mobile Research Institute)

Co-chair of the O-RAN ALLIANCE’s Technical Steering Committee,
Member of O-RAN Executive Committee,
Chief Scientist of China Mobile.

Chih-Lin I has been a distinguished expert with nearly 40 years of rich experience in wireless communications. She is a key proponent of ICDT convergence for future wireless networks. She proposed 5G being “Green and Soft” from the first day of 5G design. The philosophy continuously evolved and embraced “Open and Smart” later on, which laid out the foundation for O-RAN.


Sachin Katti
(Stanford University)

Co-chair of the O-RAN ALLIANCE’s Technical Steering Committee,
Professor of EE & CS at Stanford University.

Sachin Katti is also Co-Founder and ex-CEO of Uhana (now part of VMware), as well as previously co-founder of Kumu Networks, which is commercializing breakthrough research from his lab on full duplex radios. He received his PhD in EECS from MIT in 2009. His research has won numerous awards, including the 2008 ACM Doctoral Dissertation Award - Honorable Mention, the George Sprowls Award for Best Doctoral Dissertation in EECS at MIT, the IEEE William Bennett Prize, and the Best Student Paper Award at ACM SIGCOMM 2012.