A3 in open RAN

What is open RAN?

Open RAN (with a capital O) describes a set of standards defined by the O-RAN Alliance. The standard architecture of Open RAN is shown in the figure below, and the major parts of the architecture include:

  • The Service Management and Orchestration Framework (SMO), which will most likely form the umbrella RAN management system for all RANs going forward. It includes:
    • A design environment for rapid application development
    • A common data collection platform for management of RAN data and mediation for the O1, O2 and A1 interfaces
    • Support for licensing, access control and AI/ML lifecycle management
    • Existing OSS functions such as service orchestration, inventory/topology and policy control.
  • The RAN Intelligent Controller (RIC), which is responsible for controlling and optimising RAN functions. It has three main objectives: to receive a stream of data on which to make optimisation decisions, to ensure that services maintain the required performance levels, and to ensure RAN efficiency, balancing the needs of all users. The RIC has two components:
    • The Non-Real Time RIC (Non-RT RIC) offers closed-loop control functions which last for more than one second. Some of these functions are available today in C-SON. The placement of the Non-RT RIC in the SMO and not in the RAN is to secure access to contextual data and use it to optimise the RAN, something that the RAN nodes CU, DU and Near RT-RIC can’t do. rApps are developed for the Non-RT RIC and ingest radio environment data (e.g. device location, signal strength measurements), device data (e.g. positioning and trajectories, plus application-level information), cross-domain information (e.g. insights from the core) and external data (e.g. weather). There are a wide range of potential rApps being developed – including those involved in traffic steering, load balancing, capacity optimisation and energy optimisation. They also involve complex self-organising network functions, such as the dynamic orchestration of radio and transport domains; and various management functions, such as management of the cloud, slices and policy.
    • The Near-Real Time RIC (near-RT RIC) offers closed-loop control with functions lasting between 10ms and one second which support faster data streams and fast control of RAN functions. xApps are developed for the near-RT RIC and, unlike rApps, have access to data from specific CUs and DUs, and receive instructions from the rApps on actions to take. Use cases include network control, such as radio bearer management, load balancing, handover and interference mitigation, and mMIMO beamforming optimisation. Their development is challenging and requires specific knowledge of radio network  parameters and of currently vendor-proprietary APIs, as well as the ability to tightly interact with the vendor’s CUs and DUs.

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O-RAN overall logical architecture

Source: O-RAN Alliance White Paper, Feb 2020

Overview of the xApp/rApp market and opportunities for vendors

This section looks at the trends in xApp and rApp deployment over the next couple of years and provides some detail from analysis of their current availability.

As previously discussed, telcos have a wide range of requirements when upgrading the RAN: improved performance, cost reduction, improved spectrum and capital utilisation, as well as developing its future potential to underpin new revenues. This broad goal offers many opportunities for both RAN-specialist and other vendors to develop a range of simple to more sophisticated intelligence and automations. Opportunities will be dependent on market factors including:

  • The amount of telcos which will choose to convert, or ask vendors to convert, the already deployed capabilities of their existing C-SON into rApps/xApps. We expect this to be a popular option where the telco feels comfortable with current performance and capabilities
  • As the non-RT RIC can also interoperate with legacy RAN, which will help a smooth transition of existing capabilities into the open RAN, the number of new rApps needed in the short term might be smaller
  • Telcos, many of which will be Tier 1s with the ability to develop their own A3, will also impact the early market. Our interview discussions suggested that the majority of DIY telcos will solve specific network situations where there is no available vendor solution and that, therefore, the creation of home-grown solutions will reduce over time. However, there was also discussion of telcos wanting to become rApp developers in order to monetise their IP, which is likely to see a steady stream of app development from telcos.

Table of Contents

  • Executive Summary
    • The need for A3 within open RAN
    • A3 market development
    • Actions for telcos and vendors
  • Table of Contents
  • Table of Figures
  • Quick review: What is open RAN?
  • Overview of the xApp/rApp market and opportunities for vendors
    • rApp market
    • xApp market
    • Assessing the potential of rApps and xApps
  • A3 requirements in open RAN
    • Interference management
    • Channel estimation
    • RAN design and planning
    • Handover management
    • Load balancing
    • Traffic steering
    • RAN management
    • Beamforming
    • Service-related
    • Power management
    • The use of A3 in the SMO
  • Conclusion
  • Index

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MWC 2023: You are now in a new industry

The birth of a new sector: “Connected Technologies”

Mobile World Congress (MWC) is the world’s biggest showcase for the mobile telecoms industry. MWC 2023 marked the second year back to full scale after COVID disruptions. With 88k visitors, 2,400 exhibitors and 1,000 speakers it did not quite reach pre-COVID heights, but remained an enormous scale event. Notably, 56% of visitors came from industries adjacent to the core mobile ecosystem, reflecting STL’s view that we are now in a new industry with a diverse range of players delivering connected technologies.

With such scale It can be difficult to find the significant messages through the noise. STL’s research team attended the event in full force, and we each focused on a specific topic. In this report we distil what we saw at MWC 2023 and what we think it means for telecoms operators, technology companies and new players entering the industry.

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STL Partners research team at MWC 2023


The diversity of companies attending and of applications demonstrated at MWC23 illustrated that the business being conducted is no longer the delivery of mobile communications. It is addressing a broader goal that we’ve described as the Coordination Age. This is the use of connected technologies to help a wide range of customers make better use of their resources.

The centrality of the GSMA Open Gateway announcement in discussions was one harbinger of the new model. The point of the APIs is to enable other players to access and use telecoms resources more automatically and rapidly, rather than through lengthy and complex bespoke processes. It starts to open many new business model opportunities across the economy. To steal the words of John Antanaitis, VP Global Portfolio Marketing at Vonage, APIs are “a small key to a big door”.

Other examples from MWC 2023 underlining the transition of “telecommunications” to a sector with new boundaries and new functions include:

  • The centrality of ecosystems and partnerships, which fundamentally serve to connect different parts of the technology value chain.
  • The importance of sustainability to the industry’s agenda. This is about careful and efficient use of resources within the industry and enabling customers to connect their own technologies to optimise energy consumption and their uses of other scarce resources such as land, water and carbon.
  • An increasing interest and experimentation with the metaverse, which uses connected technologies (AR/VR, high speed data, sometimes edge resources) to deliver a newly visceral experience to its users, in turn delivering other benefits, such as more engaging entertainment (better use of leisure time and attention), and more compelling training experiences (e.g. delivering more realistic and lifelike emergency training scenarios).
  • A primary purpose of telco cloud is to break out the functions and technologies within the operators and network domains. It makes individual processes, assets and functions programmable – again, linking them with signals from other parts of the ecosystem – whether an external customer or partner or internal users.
  • The growing dialogues around edge computing and private networks –evolving ways for enterprise customers to take control of all or part of their connected technologies.
  • The importance of AI and automation, both within operators and across the market. The nature of automation is to connect one technology or data source to another. An action in one place is triggered by a signal from another.

Many of these connecting technologies are still relatively nascent and incomplete at this stage. They do not yet deliver the experiences or economics that will ultimately make them successful. However, what they collectively reveal is that the underlying drive to connect technologies to make better use of resources is like a form of economic gravity. In the same way that water will always run downhill, so will the market evolve towards optimising the use of resources through connecting technologies.

Table of contents

  • Executive Summary
    • The birth of a new sector: ‘Connected technologies’
    • Old gripes remain
    • So what if you are in a new industry?
    • You might like it
    • How to go from telco to connected techco
    • Next steps
  • Introduction
  • Strategy: Does the industry know where it’s going?
    • Where will the money come from?
    • Telcos still demanding their “fair share”, but what’s fair, or constructive?
    • Hope for the future
  • Transformation leadership: Ecosystem practices
    • Current drivers for ecosystem thinking
    • Barriers to wider and less linear ecosystem practices
    • Conclusion
  • Energy crisis sparks efficiency drive
    • Innovation is happening around energy
    • Orange looks to change consumer behaviour
    • Moves on measuring enablement effects
    • Key takeaways
  • Telco Cloud: Open RAN is important
    • Brownfield open RAN deployments at scale in 2024-25
    • Acceleration is key for vRAN workloads on COTS hardware
    • Energy efficiency is a key use case of open RAN and vRAN
    • Other business
    • Conclusion
  • Consumer: Where are telcos currently focused?
    • Staying relevant: Metaverse returns
    • Consumer revenue opportunities: Commerce and finance
    • Customer engagement: Utilising AI
  • Enterprise: Are telcos really ready for new business models?
    • Metaverse for enterprise: Pure hype?
    • Network APIs: The tech is progressing
    • …But commercial value is still unclear
    • Final takeaways:
  • Private networks: Coming over the hype curve
    • A fragmented but dynamic ecosystem
    • A push for mid-market adoption
    • Finding the right sector and the right business case
  • Edge computing: Entering the next phase
    • Telcos are looking for ways to monetise edge
    • Edge computing and private networks – a winning combination?
    • Network APIs take centre stage
    • Final thoughts
  • AI and automation: Opening up access to operational data
    • Gathering up of end-to-end data across multiple-domains
    • Support for network automations
    • Data for external use
    • Key takeaways

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