"The O-RAN Whitepaper 2024: Traffic Steering in O-RAN"
Marcin Dryjanski
Telecom Professional - Ph.D. ? Wireless Research ? Technical Trainer & Consultant ? System Architect ? Team Leader
We are pleased to introduce our latest The O-RAN Whitepaper 2024: Traffic Steering in O-RAN.
In the current heterogeneous mobile networks, traffic management is considered one of the key features to efficiently handle non-uniform user data. To realize this, the traffic steering function is employed, whose main task is to allocate users' traffic flows to network nodes or cells. O-RAN ALLIANCE provides means to support traffic steering through the utilization of Non- and Near-RT RIC frameworks and the accompanied rApps and xApps. This whitepaper provides an overview of the traffic steering topic in 5G mobile networks and how it fits into the O-RAN area. This is followed up by example implementations of the Traffic Steering xApp and its utilization for various use cases working in tandems with the corresponding rApps for energy saving and V2X scenarios.
Executive Summary
Radio traffic management is considered one of the most important functions in the current mobile networks to handle non-uniform user data. It is typically realized through traffic steering which is responsible for routing user traffic through the particular cells. This is especially important in a multi-access system, encompassing various access technologies, spectrum bands, and node types. The decision on where to place a particular user traffic is multi-dimensional and should take into account system changes in the radio environment, application requirements, and operator strategies. A customized, and individual approach to traffic distribution to the transmission nodes and user-to-cell assignment is required to fulfill the variety of QoS types in the 5G era.
This whitepaper provides a technical discussion of traffic steering, being one of the key programmability use cases related to heterogeneous networks with a specific realization within the O-RAN architecture.
The first chapter provides an overview of the traffic steering topic within the contemporary mobile wireless networks towards UE-specific cell allocation. It serves as a starting point for more details to be provided in the consecutive parts.
Then, the traffic steering is placed within the O-RAN context from the use case perspective. The key idea to put this topic within the O-RAN framework is to utilize Non- and Near-RT RIC along with the corresponding applications. Two example scenarios are presented to provide reasoning on how to approach UE-specific traffic steering.
This is followed up by an implementation example of the UE-centric strategies and proactive optimization realized as a Traffic Steering xApp within the Near-RT RIC. The uniqueness of this approach is achieved by utilizing A1 policies, guiding and adapting the behavior of the actual TS algorithm.
The next two chapters present the utilization of the TS-xApp in tandem with accompanied rApps to globally optimize radio resources for a particular use case. In the first one, Energy Saving rApp (ES-rApp) controls the operation of the TS-xApp by creating appropriate TS policies to jointly maximize energy efficiency in the network for a cell off/on use case. Here, it is important to move the traffic out of the cell before it is switched off. The second deals with V2X scenarios, where minimization of the handovers or assuring QoS for specific types of users is needed. Thus, a Traffic Management rApp (TM-rApp) is employed to create relevant policies through the A1 interface for a dynamically changing environment.
The whitepaper ends with a summary and conclusions section along with a glossary of the used terms.
Cite this:?M. Dryjanski, L. Kulacz, A. Kliks, "The O-RAN Whitepaper 2024 – Traffic Steering in O-RAN”, Whitepaper, Rimedo Labs, April 2024
Contents
Executive Summary
Chapter 1.0 Introduction to Traffic Steering
Chapter 2.0 Traffic Steering Use Case in O-RAN
Chapter 3.0 Traffic Steering xApp Implementation
Chapter 4.0 Energy Saving rApp control over Traffic Steering xApp
Chapter 5.0 Traffic Management for V2X Scenarios
Summary and Conclusions
Glossary
References
[1] M. Dryjanski and M. Szydelko, "A unified traffic steering framework for LTE radio access network coordination," in IEEE Communications Magazine, vol. 54, no. 7, pp. 84-92, July 2016
[2] O-RAN ALLIANCE WG1, “O-RAN Use Cases Detailed Specification, v.10.00,” O-RAN ALLIANCE, Tech Specification, Mar 2023
[3] “Policy-based Traffic Steering xApp implementation within O-RAN”, https://rimedolabs.com/blog/policy-based-traffic-steering-xapp-implementation-within-o-ran/
[4] O-RAN.WG2.Use-Case-Requirements-v02.01, “Non-RT RIC & A1 Interface: Use Cases and Requirements”, O-RAN Alliance, Nov. 2020
[5] O-RAN WG2, “O-RAN A1 interface Application Protocol specification”, O-RAN.WG2.A1AP-v03.01, Jun 2021
[6] X. Xu, C. Yuan, W. Chen, X. Tao, and Y. Sun, ?Adaptive Cell Zooming and Sleeping for Green Heterogeneous Ultradense Networks,” IEEE Transactions on Vehicular Technology, vol. 67, no. 2, pp. 1612-1621, Feb. 2018.
[7]?Dryjański, M.; Ku?acz, ?.; Kliks, A. Toward Modular and Flexible Open RAN Implementations in 6G Networks: Traffic Steering Use Case and O-RAN xApps. Sensors 2021, 21, 8173. https://www.mdpi.com/1424-8220/21/24/8173
[8] O-RAN ALLIANCE WG2, ?A1 Interface: Type Definitions, v02.00”
[9] Traffic Management for V2X use cases in O-RAN;?https://rimedolabs.com/blog/traffic-management-for-v2x-use-cases-in-o-ran/ [10] O-RAN ALLIANCE WG1, ?Use Cases Detailed Description, v.12.00,” O-RAN ALLIANCE, Tech. Rep., Oct. 2023 [11] O-RAN ALLIANCE WG1, ?O-RAN Architecture Description, v.10.00,” O-RAN ALLIANCE, Tech. Rep., Oct. 2023 [12] Eclipse, ?SUMO – Simulation of Urban MObility”,?https://eclipse.dev/sumo/
To download the Whitepaper, go to The O-RAN Whitepaper 2024: Traffic Steering in O-RAN.
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