O-RAN ALLIANCE Summit - Accelerating Open RAN Adoption

23 New O-RAN Specifications Have Been Released in The First Half Of 2020

By Chih-Lin I and Sachin Katti.

In its specification effort, O-RAN has been extending RAN standards with open interfaces and intelligent RAN functions. Recently published specifications bring new or updated features to all parts of the O-RAN architecture, allowing vendors to progress with improved O-RAN based implementations.

Published in February 2020, the O-RAN Use Cases and Deployment Scenarios white paper introduces the initial set of O-RAN use cases and cloud native deployment support options.

O-RAN use cases drive the O-RAN architecture and demonstrate its unique benefits, including utilization of AI/ML modules to empower network intelligence through open and standardized interfaces in a multi-vendor network. The white paper also introduces the O-Cloud computing platform that can host relevant O-RAN functions to enable flexible deployment options in virtualized telco clouds. The full white paper is available at the O-RAN Architecture and Resources web page.

In accordance with the white paper, O-RAN specifications provide technical level setting standards for current vendor implementations and O-RAN open source software development. The specifications are delivered by O-RAN Work Groups, which reflect the overall O-RAN Architecture.

WG1: Use Cases and Overall Architecture Workgroup

OAM architecture specification v03.00

This document defines the OAM framework in an O-RAN network. It provides a set of basic end-to-end use cases and derives associated requirements for O-RAN OAM. It then defines O-RAN OAM building blocks such as O-RAN management services, managed functions and managed elements and identifies different OAM models and deployment examples for O-RAN. An Appendix attached provides templates for the use of PlantUML-based sequence diagrams. This version also adds use cases for Data Collection, aligns models and terminology with the O-RAN Architecture Description v1.0, and adds an Annex mapping with 3GPP management system concepts.

O1 specification v03.00

This document defines O-RAN OAM interface functions and protocols for the O1 interface, which is the management interface between Service Management and Orchestration and O-RAN Managed Elements. This version adds CM Services Subscription Control, Streaming PM, and requirements to be applied when creating O-RAN defined PM measurements. It also includes some updates to existing services including the renaming of Communication Surveillance to Heartbeat Management Service, updates on supported heartbeat events and heartbeat control.

O-RAN Use Cases Analysis Report v02.00

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.

O-RAN Use Cases Detailed Specification v02.00

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.

Study on O-RAN Slicing Technical Report v02.00

This document provides common terminology for slicing, an overview of slicing activities in different SDOs (3GPP, ETSI, ONAP, GSMA, etc.), and a high level view of O-RAN slicing framework and architecture along with various deployment options.

O-RAN Slicing Architecture Specification v01.00

This document describes at a high level the 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.

O-RAN Architecture

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

AI/ML workflow description and requirements, Technical Report, Version 1.1

This document provides details on AI/ML model design, composition, and model runtime access to data and the model deployment solutions. Criteria for determining various ML training host and ML inference host deployment options is highlighted. It also elaborates on AI/ML models used in O-RAN use cases aligned with the WG1-Use Case Task Group work effort.

Use Case and Requirements, Specification, Version 2.0

This document describes the set of use cases that have been approved within O-RAN WG2. It helps identify requirements for Non-Real-Time Radio Intelligent Controller (Non-RT RIC) and A1 interface and will lead to formal drafting of interface specifications. The motivation, resources, steps involved and data requirements for each use case are described, followed by the respective functional and non-functional requirements derived therein.

A1 Interface: Application Protocol, Specification, Version 1.1

This document optimizes A1 interface definition for single-policy operations. It includes Open API Specification and updated descriptions for enhanced realization.

WG3: The Near-real-time RIC and E2 Interface Workgroup

Near-RT RIC Architecture Version 1.0

This new specification defines the internal architecture of O-RAN Near-Real-Time Radio Intelligent Controller from a functional perspective. It describes general principles, requirements and basic functions for Near-RT RIC, such as database, xApp subscription management, conflict mitigation, etc. It also provides an outline of Open APIs, which are the internal interfaces to enable 3rd-party xApps.

E2 Interface Specifications Version 1.0

This new specification defines the functions and protocols of the E2 interface, which connects the O-RAN Near-RT RIC to the underlying O-RAN nodes (i.e. E2 nodes). The collection of documents describe the general architecture of Near-RT RIC, the main functions/procedures supported over E2, the detailed signalling procedures between the two endpoints, and the E2 Service Model (E2SM), which defines how specific functions located in the O-RAN Node can be controlled by the Near-RT RIC over E2. This version includes two E2SM documents, one describing  inter-node network interfaces and the other exposing network measurements towards the Near-RT RIC.

WG4: The Open Fronthaul Interfaces Workgroup

Open Fronthaul Conformance Test Specification Version 1.0

This document defines non-intrusive Conformance Testing of OFH Syntax, Semantics and Device operation to meet 3GPP standards for each of the Fronthaul M-Plane, S-Plane and C/U-Planes. The M-Plane Conformance Tests cover syntax and RPC operation for general functions, including initialization, alarms, software update, access control, and Log retrieval. The U/C-Plane Conformance Tests include 4 test scenarios:  FDD FR1 Conducted, FDD FR1 OTA, TDD FR1 Conducted and TDD FR1/FR2 OTA. This version focuses on tests for the O-RU under FDD FR1 Conducted mode, and covers Resource Allocation, Beamforming, Compression, Delay Management, Transport, LAA, LTE and PRACH. The S-Plane Conformance Tests focus on O-RU testing using ITU-T G.8275.1 profile for LLS-C1/C2/C3, and both functional and performance tests are defined.

Control, User and Synchronization Plane Specification v03.00

This document provides significant updates including: the Shared Cell capability, Dynamic Spectrum Sharing parameters, the ability to convey multiple beamforming weight sets at once, the ability to describe multiple antenna ports with a single C-Plane command, O-DU synchronization requirements, selective RE sending on the U-Plane, little-endian data formats, and several fronthaul performance measurement counters. It also clarifies PRACH timing parameters, Section Extension optionality, interactions among several Section Extensions, and correction of several minor errors that existed in the v02.00 specification.

Management Plane Specification v03.00

This document fixes known bugs in v02.00, including the NETCONF access control privileges, CU plane monitoring, synchronization state transitions as well as ordering of start-up procedures. V03.00 Introduces a new chapter that describes the management plane operations for shared cell operation, and the corresponding YANG functionality using two new models. Existing functionality is enhanced, with capabilities such as dying gasp, configuration notification, dynamic spectrum sharing, new energy, power and environmental measurements as well as the ability to group eAxC-IDs together.

Fronthaul Interoperability Test Specification (IOT) v02.00

This document provides updates including: hybrid mode testing (read-only tests), delay management testing, uplink throughput testing, and additional parameters to existing NR TDD IOT profiles, and new IOT profiles for NR FDD, LTE FDD and LTE TDD. It also removes a variety of FFS reflecting updates in the CUS/M-Plane and the Conformance Test spec.

Cooperative Transport Interface Transport Control Plane Specification v01.00

This new specification describes the Cooperative Transport Interface (CTI) and related message protocol when the fronthaul between the O-DU and O-RU is realized via a resource allocation based transport network (such as PON or DOCSIS). The intent of providing cooperation between the O-DU and the transport network over CTI is to make the upstream bandwidth allocation pro-active by anticipating the bandwidth needs of the radio traffic and thus to greatly reduce the transport latency due to the allocation process.

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

Interoperability Test Specification Version 1.0

This specification specifies the IOT for eNB and en-gNB connected using the X2 interface implemented in accordance to the WG5 C-plane and U-plane profiles. Its scope is EN-DC X2 inter-operability verification. The NR C-Plane includes 16 test cases for basic use cases specified in O-RAN NR C-plane profile for EN-DC Version 2.0, whereas the NR U-Plane includes 7 test cases for use cases specified in O-RAN NR U-plane profile for EN-DC Version 2.0.

O-RAN Transport specification v01.00

This document clarifies the Transport layer functions required/recommended for O-CU, O-DU, and eNB. It is applicable to X2/F1 interfaces. Requirements of three classes are specified: Basic functions, Ethernet (for PNF), and [Vn-Nf]/N/L3 Service (for VNF).

WG6: The Cloudification and Orchestration Workgroup

Cloud Architecture and Deployment Scenarios v02.00

This document provides updates to align with the latest O-RAN architecture. It comes with an updated O-Cloud description and further introduces key aspects such as the O2 Interface and its services, the Acceleration Abstraction Layer (AAL), and the Time Synchronization.

Cloud Platform Reference Design for Deployment Scenario B v01.00

This version focuses on O-Cloud deployment scenario B (as defined in the O-RAN Cloud Architecture and Deployment Scenarios for O-RAN Virtualized RAN Version 2.0 technical report). It specifies the O-Cloud architectural components and requirements, and also provides an O-Cloud platform reference design for both hardware and software.

Orchestration Use Cases and Requirements for O-RAN Virtualized RAN v01.00

This document introduces use cases and associated requirements for the management and orchestration of O-RAN virtualized RAN, including generalized requirements and requirements supporting the O2 interface between the Service Management and Orchestration Framework and the O-Cloud Infrastructure, Management Services/Deployment Management Services, and the O1 interface for OAM of Virtualized Network Functions.

WG7: The White-box Hardware Workgroup

Indoor Picocell Hardware Architecture and Requirement (FR1 Only) v01.00

This new specification describes the Architecture and Requirements for all Indoor Picocell deployment scenarios as specified in O-RAN Deployment Scenarios and Base Station Classes For White Box Hardware Version 1.0.

WG8: Stack Reference Design Workgroup

AAD specification release 2

This document describes the reference software architecture and APIs for O-CU and O-DU implementation. This version of the specification includes complete description of L1 (PHY) functional blocks, updates and new APIs in L2 and L3 layers as well as a full description of MAC-Scheduler APIs.

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.