Open RAN principles

Question 1

Preface

Accepted Answer

The UK government is committed to building the security and resilience of critical network infrastructure by enhancing competition and innovation within the telecoms supply chain. As set out in the UK 5G Supply Chain Diversification Strategy (‘the strategy’), and through the advice of the Telecoms Supply Chain Advisory Council and extensive engagement with governments and industry across the world, we aim to drive this change by accelerating the development and deployment of open interface architectures, such as Open RAN.

This document is not intended to be the definitive answer to the question ‘What is Open RAN?’. Instead it sets out the foundations for an effective and functioning telecoms supply market and the priorities that will inform our approach, including as we deliver our £250 million programme of Open Networks R&D. It sets out the characteristics Open RAN - and the market - should possess to deliver on the potential highlighted in the strategy: collectively, ‘The Open RAN principles’. The intention is that these principles drive further discussion across governments and industry over how best to support the maturation of Open RAN to ensure that it delivers on its promise. We welcome further discussions with interested parties on how Open RAN should be defined and assessed going forward and consider these principles as the starting point for those discussions.

Question 2

Summary

Accepted Answer

In an increasingly digital world, secure and reliable digital connectivity has become a necessity for citizens and businesses. We are ever more dependent on our telecommunications networks for all aspects of our lives, so it is essential for our economy and way of life that those networks are resilient. Increasing vendor diversity for telecommunications networks is an essential goal for the UK and other governments internationally, to enhance security, resilience, innovation and competition in critical national infrastructure and beyond. This need is particularly acute in the mobile radio access network (RAN), as set out in the UK 5G Supply Chain Diversification strategy.^{[footnote 1]} The strategy identifies the success of open-interface solutions, such as Open RAN, as an important element for driving diversification. To ensure that Open RAN achieves these goals, the industry and like-minded public bodies should adopt the following principles:

Open disaggregation, allowing elements of the RAN to be sourced from different suppliers and implemented in new ways.
Standards-based compliance, allowing all suppliers to test solutions against standards in an open, neutral environment.
Demonstrated interoperability, ensuring disaggregated elements work together as a fully functional system — at a minimum matching the performance and security of current solutions.
Implementation neutrality, allowing suppliers to innovate and differentiate on the features and performance of their products.

Approaches that suppliers and network providers could adopt which will assist in achieving these principles include:

avoid fragmentation of specifications and splits, initially focusing on the smallest possible number of options for disaggregating networks
prioritisation and optimisation of the requirements and priorities of mobile operators and other network builders
an open, transparent and inclusive approach, compliant with WTO rules, to developing standards and protecting intellectual property, allowing fair access by new players and facilitating external scrutiny
assurance of compliance with open standards via neutral testing environments
transparency of market information, in particular transparency of access to relevant essential intellectual property

These principles are consistent with the Prague Proposals on Telecommunications Supplier Diversity which the UK and other governments supported in 2021.^{[footnote 2]}

Aims

Telecoms networks are essential infrastructure for modern society. Yet the number of vendors providing the key components of that infrastructure has diminished dramatically over the last few years, to the point where the most critical infrastructure of modern UK networks is being built out using only two vendors. The strategy sets out how increasing the diversity of suppliers is therefore essential, as a means of enabling four major outcomes:

Security and resilience: ^{[footnote 3]} Our telecoms networks represent critical national infrastructure, enabling a wide range of essential public and private services. In that context, it is essential to ensure their security and their resilience. The impact of malicious functionality being added to equipment by a hostile actor or a vulnerability being exploited increases when there is a lack of vendor diversity, due to the widespread impact each vendor has on operators around the world. Increasing the number of vendors and reducing the number of proprietary interfaces, should go hand-in-hand with greater openness and scrutiny of standards development and implementation. This will enable security researchers to identify and address potential threats and attacks rapidly as they arise. By promoting vendor diversity therefore, we seek to strengthen the ability of critical national networks to continue to function under threats including cyber attack and supplier exit, and for any vulnerabilities to be identified and rectified swiftly, with minimal impact.

Innovation:^{[footnote 4]} A continuous pipeline of ongoing innovation will be needed in the future to keep up with the expected growth in data demand,^{[footnote 5]} to address new challenges, such as the need to reduce the energy consumption of networks, and to provide services to other specialist industries rather than only consumers. As long as there are only a small handful of telecoms vendors in the major networks, there are barriers to new and adjacent companies bringing their specialist skills into telecoms, making it harder for those companies to find the necessary investment and ultimately hindering the pace of innovation.

Competition: All of these outcomes can be facilitated by ensuring that the conditions are right for a proliferation of vendors of both telecoms networks and of the components and subcomponents which make them up, enabling a more open, dynamic and efficient market for telecom technology and the services and expertise needed to build and operate networks based on that technology.

These outcomes are desirable for all telecoms networks, but our focus here is on the critical area of the mobile radio access network (RAN). The RAN constitutes by far the biggest expense in the network,^{[footnote 6]} requires the most rapid improvements in diversity and performance, and requires the most specialist skills to develop, integrate and operate.

The concept of Open RAN has arisen as the main route to enabling RAN vendor diversification, and with it achieving the four outcomes highlighted above. Yet while there is intensive global activity across industry groups and companies to develop Open RAN specifications and products, there is no consistent interpretation of what true Open RAN looks like. Without this, there is a risk that Open RAN may be developed in such a way that it does not deliver on its potential benefits, or that standards may be dominated by particular interests. There have been several previous attempts to create open base station standards which have failed to deliver the expected benefits. By setting out clear Open RAN principles we seek to avoid these risks and ensure Open RAN can deliver on its promise to facilitate the sustainable growth of a competitive and innovative market, with resilient and secure mobile networks. We have prepared these principles taking into account the views of industry bodies such as the Open RAN Policy Coalition^{[footnote 7]} and Telecom Infra Project, as well as discussions with UK operators, other network deployers and Open RAN suppliers. We will use these principles to guide our future support for the UK mobile market, and will work with like-minded bodies globally to embed the principles in the international market.

Question 3

Market needs

Accepted Answer

For the RAN market to function effectively, it needs to deliver transparency of information, minimised barriers to entry and standardised interfaces between parts, while still enabling suppliers to innovate in the approaches they take to meeting market requirements.

An ideal outcome for the telecoms market would be true interchangeability of parts. Such parts can more easily be compared by prospective purchasers, combined in ways to produce custom systems without sacrificing economies of scale, to be replaced easily to avoid vulnerabilities and to create a wider accessible market for suppliers.

The interchangeability of parts is not a concept which originated in telecoms: the standardisation of design of mechanical parts enabled a thriving manufacturing industry in the nineteenth century, and the standardised networking of computing enabled the rapid proliferation of the internet in the 1990s and 2000s^{[footnote 8]}. We take this interchangeability of parts for granted today.

Full interchangeability is however an aspirational goal. En route to interchangeability we at least aim for interoperability, where parts can be connected with minimal friction via testing and a minimum of adjustments by following common, open standards and specifications to address a wide range of requirements.

The telecoms industry is very capable of achieving interoperability: the ability of a mobile phone to go anywhere in the world and still work is testament to this, and is responsible for allowing very advanced technologies to be miniaturised and delivered at a price affordable to billions around the world. Similarly, the radio access networks and the core networks from different vendors can be interconnected successfully.

Yet such interoperability — let alone interchangeability — is not available within the RAN. In individual cases, vendors can work together to exchange proprietary information on their implementations, allowing for example different vendors to deliver the RAN in different regions of the country, but a higher degree of interoperability is needed for Open RAN in order to address the barriers to entry that have led to the current position of market failure.

Question 4

Open RAN principles

Accepted Answer

What is Open RAN?

Fundamentally, Open RAN is the disaggregation of the radio access network into parts which are interconnected by open, standards-based, interoperable interfaces, using open, standards-based protocols for communicating over those interfaces. As a result, networks can be built from parts from different vendors.

We believe that to ensure that Open RAN achieves its potential, it needs to be defined by four core principles:

Open disaggregation.
Standards-based compliance.
Demonstrated interoperability.
Implementation neutrality.

Open disaggregation

Open RAN moves away from an assumption that the entire end-to-end RAN has to be provided by a single vendor. Instead, it is split into functional elements which can be provided by different vendors, interconnected via open interfaces. These interfaces may be between hardware elements, software components, or the software-hardware split. The choice of the specific split between functions has received much attention in the industry, and there may be more than one sensible approach to the split: for example the most suitable split to separate portions of the base station may be different for outdoor deployment compared with indoors. These options should not however lead to a fragmented market, particularly as the Open RAN market is in its infancy. And in establishing the Open RAN market, fewer options is better to allow different subsystems of the RAN (including radio components, processing hardware and software elements) to be sourced from different suppliers. This is reflected in the current emerging industry consensus to focus on the splits defined by O-RAN Alliance^{[footnote 9]} and the Small Cell Forum.^{[footnote 10]}

Over time, additional splits may be needed, for example between hardware and software or between processing units with greater granularity than the current functional splits, but without prescribing a single approach to implementation.

Standards-based compliance

Open disaggregation is a crucial step, but in order to achieve interoperability the open interfaces between these disaggregated parts must be standardised. Failure to do so will inevitably lead to the proliferation of proprietary extensions. This will in turn lead to the formation of end-to-end solutions by one vendor, or coalitions of partnered vendors, effectively re-aggregating the RAN into a single ‘black box’ once again. Open RAN solutions should therefore adopt and adhere to industry-driven standards across all interfaces to ensure that the disaggregation of the RAN is sustainable.

It is recognised that creating fully interchangeable parts is an ideal goal rather than a fixed requirement and that swapping parts from different vendors will require some testing and engineering to ensure optimal operation. However, adoption of standardised interfaces ensures that vendors seeking to interoperate start from a much closer position. Reducing the ‘friction’ involved in swapping components by decreasing the effort and cost for integration and interoperability testing.

Demonstrated interoperability

Standardised interfaces and protocols between the parts of the RAN are necessary - but not sufficient - to achieve the goals of Open RAN. Telecoms has many open, standardised interfaces which nevertheless do not ensure interoperability, because they do not specify enough of the details, leaving implementations open to interpretation and to vendors including proprietary extensions, which have the effect of preventing choice.

The only way to ensure that products are genuinely interoperable is to demonstrate actual operation with other vendor products in realistic environments, while delivering both the required functionality and performance. It may not be necessary or attractive for every mobile site to use a mix of vendors: but the equipment which is deployed needs to be demonstrably interoperable on other sites, not just compliant to open standards. Interoperability is needed not only between functional elements within each base station, but also between adjacent base stations as well as between the base stations and the core and management networks that support the RAN. Previous initiatives have succeeded in creating open interfaces, but failed to deliver multi-vendor interoperability because of proprietary management approaches. These interoperable chains should be able to demonstrate performance, security and efficiency, at least on par with existing market solutions.

Implementation neutrality

Open RAN should be neutral to the technologies used to implement it to avoid favouring one vendor’s implementation over another, and to avoid hampering innovation. Standards should leave space for differentiation so price is not the only differentiator. Industry should be able to evolve the implementations to meet evolving network needs, without compromising on these principles.

For example, the mix of hardware and software, and the physical embodiment of products should all be vendor choices, and system integrators should help avoid the emergence of separate islands of vendors. While there is a strong trend toward virtualised networks implemented in software, innovation in materials and devices is also important to achieve performance goals such as support for new frequencies and low energy consumption. Technologies such as open source software may have a role but are not a requirement, rather an implementation choice.

The approach should thereby leave space for innovation and vendor differentiation by allowing a flexible approach to implementing networks in an appropriate combination of software and hardware.

Question 5

Approaches to realising the Open RAN principles

Accepted Answer

Although industry progress is promising, today’s Open RAN products and specifications do not yet fully match the principles set out above. Achieving them will take time and require a combination of approaches, such as those set out below:

1). Avoid fragmentation of the nascent market by focusing on the smallest possible number of options for disaggregating networks. This means focusing on developing the minimum number of specifications, splits, standards, and standards bodies. This should have the dual benefits of accelerating progress and reducing complexity for entrants, as set out in the Prague Proposals.

2). Prioritise development in accordance with the requirements and priorities of mobile operators and other network builders, to encourage adoption of Open RAN solutions at scale and pace. For example, a group of major operators have set out their technical priorities.^{[footnote 11]}

3). Ensure that the principles are applied to ensure an industry ecosystem in a timescale which allows network operators to benefit from Open RAN in their 5G network rollout, and are embedded from the beginning in 6G definition.

4). Standards bodies and industry groups should adopt an open and rigorous approach to making standards and protecting intellectual property, allowing fair access by new players and external scrutiny, including by public bodies.^{[footnote 12]} This process should be compliant with WTO principles.^{[footnote 13]} Access to standards making processes by public authorities is necessary to ensure standards embed cyber security in line with the Prague Proposals, and to ensure that overall security is enhanced by open practices despite the opening up of additional interfaces. The onus and responsibility to lead standards-making is with industry, but external scrutiny can support and ensure favourable outcomes.

5). Assurance of compliance with standards via neutral testing environments, ensuring all combinations of vendors can test their implementations against available standards and to ensure that standards have sufficient scope and clarity to promote interoperability.^{[footnote 14]}

6). Transparency of market information: The current closed nature of the RAN market makes it difficult for those deploying networks to make good choices, and for new vendors to establish and compare their products in terms of both performance and associated pricing. It also makes it difficult to establish the provenance of critical subcomponents in the supply chain. To establish a proper marketplace for RAN equipment, transparency needs to be substantially improved. This applies to the specifications for products, allowing comparison of the features and performance of offerings between vendors.^{[footnote 15]} We also should be able to see more detail in the intellectual property embodied in the standards: providers should be more explicit on what intellectual property items apply to what parts of specifications, removing post hoc jeopardy for companies entering the market. We support a market where IP is declared upfront by providers and made available on fair, reasonable and non-discriminatory terms. Transparency should be supported throughout the supply chain, via assessment of ownership, partnership, and corporate governance structures of suppliers of critical components.

Question 6

Conclusion

Accepted Answer

Diversification of the telecoms network supply chain is essential to preserve and enhance the security, resilience, innovation and competitiveness of telecoms networks. Open RAN is a promising route to enabling that diversification for mobile and wireless networks but needs clarity on its aims to ensure its effectiveness. We consider that adhering to the Open RAN principles and Approaches laid out in this document will help ensure the existing international efforts to define and implement Open RAN are well directed.

The UK government has already taken steps to accelerate the development of open interface RAN solutions, following the commitment made in the 5G Supply Chain Diversification Strategy. £36m of investment across the 15 winners of the Future RAN Competition (FRANC)^{[footnote 16]} was announced in December, along with a further £15m of funding to expand the SmartRAN Open Networks Interoperability Centre (SONIC). Funding R&D to develop mature RAN components that are interoperable by default, and creating neutral facilities for suppliers to test these components, will enable industry to work towards Open RAN solutions that adhere to these principles. Widespread adoption of Open RAN of this ilk promises to address the resilience, innovation and competition challenges set out in the strategy, benefiting society, consumers, and the economy.

These principles will be the foundation of future UK interventions in Open RAN, as we strive towards developing solutions which possess these characteristics in order to deliver our objectives for secure and resilient networks in an innovative and competitive market. We encourage industry bodies to adopt these principles to ensure that Open RAN develops in the most effective way. For suppliers this means ensuring products are developed with these attributes, while network operators should strive to deploy open architectures that adhere to these principles. Furthermore, as we progress this activity we look forward to working with international government partners and encouraging a shared approach on this issue, to ensure we best meet our mutual goals of a more competitive and vibrant telecoms supply market. A common approach to developing and deploying Open RAN will ensure it realises its potential to drive innovation and competition in the market — both now and for the long term. We believe that these principles can be the foundation upon which that common approach is built.

Open RAN principles

Preface

Summary

Aims

Market needs