„The O-RAN Whitepaper”

We are pleased to introduce „The O-RAN Whitepaper 2021” by Rimedo Labs. This post describes the contents of the whitepaper.

Introduction

Currently, one of the hot topics in Telecoms world is Open RAN. This whitepaper provides a technical discussion in this field. It starts with a definition of Open RAN as a trend. This is followed up by an overview of O-RAN, a term introduced by the O-RAN Alliance, a standardization entity, whose mission is “to re-shape the RAN industry towards more intelligent, open, virtualized and fully interoperable mobile networks”. The overall concept of O-RAN is provided together with entities involved in the ecosystem’s creation.

Later, the whitepaper discusses the different nodes and interfaces creating the flexible and disaggregated O-RAN architecture along with various options for implementation.

Next, more details are provided of the O-RAN concept with the topic of RAN Intelligent Controller (RIC). RIC provides the possibility to manage the radio resources and radio network. It is designed within O-RAN architecture as a separate entity together with Radio Resource Management (RRM) or Self-Organizing Networks (SON) functions defined as xApps.

The idea of having RIC is to be able to efficiently manage and optimize the RAN’s operation. By using the concept of open interfaces and xApps, O-RAN enables the provision of tailored algorithms for specific use cases. O-RAN Alliance specifies preliminary use cases and defines the policy framework by which the algorithms to support the use cases can be controlled.

The final part of the whitepaper provides an overview of the use cases, followed by a detailed discussion of the Traffic Steering use case. Discussion continues of the use case requirements, operation of the O-RAN nodes, along with the specified interfaces, and a description of the scenario as defined in O-RAN Alliance specifications. The whitepaper is finalized with a summary and conclusions section along with a glossary of the O-RAN terms.

Cite this: M. Dryjanski, R. Lundberg, „The O-RAN Whitepaper 2021 – O-RAN Overview, Architecture and Use Cases”, Whitepaper, Rimedo Labs, June 2021

The O-RAN Whitepaper Contents

Chapter 1.0 Introduction to Open RAN

Like almost everything in Telecoms, Open RAN is complicated. It’s not a single idea. It’s not a single product or service. It’s not an optimization technique
or path towards improved efficiency. In fact, it’s hardly even an agreed term. You’ll find references in the literature to Open RAN, OpenRAN, ORAN, and O-RAN (see e.g., [1-7]). The general trend is called Open RAN and as such we will use it throughout this chapter. The later chapters will focus on the technicalities as per O-RAN Alliance thus, we’ll use the term O-RAN (with the „dash”).

• 1.1 General Open RAN idea
• 1.2 Disaggregation
• 1.3 Discrete functions with well-defined interfaces
• 1.4 What motivates Open RAN?
• 1.5 Market concentration
• 1.6 Avoiding vendor lock-in
• 1.7 Not repeating the Over-The-Top (OTT) debacle
• 1.8 Hyperscalers
• 1.9 Independent Software Vendors (ISVs)
• 1.10 Innovation

Chapter 2.0 O-RAN Overview

This chapter provides an introduction to O-RAN. First of all, to avoid misunderstandings, the thing that is subject to the discussion is the O-RAN with the “dash”. This is the
Open RAN as defined by O-RAN Alliance, an entity, which mission is “to re-shape the RAN industry towards more intelligent, open, virtualized and fully interoperable
mobile networks” [1].

• 2.1 RAN Transformation
• 2.2 Radio Access Network using O-RAN concept
• 2.3 Entities involved in the O-RAN developments
• 2.4 O-RAN Alliance specifications

Chapter 3.0 O-RAN Architecture, Nodes, and Interfaces

In the previous chapter, the overall O-RAN concept as provided by O-RAN Alliance was presented. This one discusses the different nodes and interfaces creating
the flexible and disaggregated O-RAN architecture along with various options for implementation

• 3.1 O-RAN nodes
• 3.2 O-RAN architecture
• 3.3 O-RAN implementation options

Chapter 4.0 O-RAN near-Real-Time RAN Intelligent Controller

In the previous chapter, the overall O-RAN concept as provided by O-RAN Alliance was presented. This one discusses the different nodes and interfaces creating
the flexible and disaggregated O-RAN architecture along with various options for implementation

• 4.1 O-RAN near-RT RIC
• 4.2 near-RT RIC implementation options
• 4.3 near-RT RIC deployment flexibility

Chapter 5.0 O-RAN Use Cases: Traffic Steering

One of the key elements of having RIC (and the overall O-RAN concept for the management of radio networks) is to be able to efficiently manage and optimize the radio network. By using the concept of open interfaces and xApps, O-RAN enables tailored algorithms for specific use cases. O-RAN Alliance specifies preliminary use cases
and defines the policy framework by which the algorithms to support the use cases can be controlled. This chapter provides an overview of the use cases, which is followed by a detailed discussion of one of them, namely Traffic Steering. We discuss the use case requirements, operation of the O-RAN nodes with the specified interfaces and describe the scenario as characterized in O-RAN Alliance specifications

• 5.1 O-RAN use cases
• 5.2 Traffic Steering use case
• 5.3 Traffic Steering use case operation within O-RAN
• 5.4 Example TS Use Case

Summary and conclusions

In this whitepaper, we provided an introduction to O-RAN, where we set up the scene and showed basics like characteristics of O-RAN, the basic building blocks as well as entities involved in the development of this concept.

Later, in chapter 3.0 we discussed the nodes and interfaces defined by O-RAN Alliance. The provided implementation options visualize one of the benefits of O-RAN, namely the implementation flexibility with the open O-RAN architecture. On the one hand, those options provide the flexibility in implementation and various vendor configurations, but the price to pay for this variety is that you need a way to identify the internal nodes that you want to control, i.e. it requires the E2 and O1 interface to be able to capture all those different options and encapsulate control elements e.g., for O-DU only

near-RT RIC is one of the key elements in the O-RAN architecture, which allows feeding an “external” intelligence into the operations of the radio network. It creates a platform to which the vendors (either software vendors, or Telco vendors, or xApp developers) could provide per-use case RRM algorithms to allow adaptation/optimization radio resources usage for specific scenarios. It will be interesting to see how the creation of the ecosystem for those applications will play out. Will there be Google Plays and xApp Stores for the Telco world?

The final chapter 5.0 closes the bracket of our O-RAN discussion concerning the architecture, design, and application scenarios. We went from the overall description of use cases as per O-RAN Alliance specifications finalized by showing a particular example of Traffic Steering. Each of the use cases described in the first part of chapter 5.0 is detailed in [15] with similar elaboration. Traffic Steering, discussed in this chapter is an important element of the current mobile systems due to the multitude of options for
cell assignment and multi-node transmission, and as such are addressed by O-RAN Alliance in the so-called “Phase I”.

References

[1] O-RAN ALLIANCE (o-ran.org)

[2] 3GPP

[3] Open Networking Foundation

[4] SD-RAN – Open Networking Foundation

[5] Telecom Infra Project | Global Community Connectivity collaboration

[6] OpenRAN – Telecom Infra Project

[7] Home – Open RAN Policy Coalition

[8] O-RAN Software Community

[9] O-RAN Virtual Exhibition

[10] Open RAN Small Cell Forum

[11] O-RAN.WG1.O RAN Architecture Description v03.00, “O-RAN Architecture Description”, O-RAN Alliance, November 2020

[12] O-RAN ALLIANCE Introduces Minimum Viable Plan Towards Commercial O-RAN Solutions and 28 New O-RAN Specifications Released Since November 2020

[13] O-RAN.WG3.RICARCH-v01.01, “Near-Real-time RAN Intelligent Controller (Near-RT RIC) Architecture”, O-RAN Alliance, November 2020

[14] ORAN-WG3.E2SM-KPM-v01.00.00, “O-RAN Near-Real-time RAN Intelligent Controller E2 Service Model (E2SM) KPM”, O-RAN Alliance, February 2020

[15] O-RAN.WG2.Use-Case-Requirements-v02.01, “Non-RT RIC & A1 Interface: Use Cases and Requirements”, O-RAN Alliance, Nov. 2020

[16] “O-RAN Use Cases and Deployment Scenarios”, O-RAN Alliance Whitepaper

To download the Whitepaper, go to The O-RAN Whitepaper 2021

Other Resources from Rimedo Labs

• To check our blog posts on #AllThingsWireless, visit: Blog – RIMEDO Labs
• Webinar: A video recording from an O-RAN Webinar: O-RAN Architecture and Use Cases – YouTube
• To download the slides from the O-RAN Webinar, visit: slides on O-RAN Architecture and Use Cases
• Training: Sign up for our O-RAN System Overview Course.
• Poster (High quality, printer-friendly, A3): Subscribe to get your O-RAN Poster copy.

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