UK activities must be harmonised with international standards and best practice. Mobile network products being interoperable across the world will ensure the UK benefits from economies of scale, while opening the path to overseas business for UK vendors. Any fragmentation of the UK market away from European and global trends would risk leading to sub-scale opportunities and therefore devaluing UK ecosystem collaboration efforts.
UK ecosystem initiatives retaining a global harmonisation focus is therefore key; indeed avoiding fragmentation is one of UK Government’s six approaches to realising Open RAN.
Working with policymakers internationally can deliver synergy dividends and avoid conflicts and fragmentation; accordingly the UK has signed up to the Prague Proposals.
On the demand side, looking at mobile operators Vodafone, Telefonica and DT (a BT shareholder), the UK is host to three of Europe's Big Five Open RAN coalition, who are seeking concerted European support and EU investment. All three groups also carry out some of their global Open RAN development activities in the UK.
Interoperability Standards for Open Networks
Assurance of compliance with standards via neutral testing environments is one of the six approaches identified by DCMS for realising Open RAN. Several organisations outside the UK provide Open RAN certification or test and validation ‘badges’, most notable being the O-RAN Alliance and TIP.
Since the emergence of Open RAN disaggregation, CPRI has had somewhat of a resurgence; it can be seen from a historical perspective as an early attempt to bring some level of globally harmonised open interface into a closed ecosystem, but this was (and continues to be) far from an open RAN standard. CPRI proprietary layers still exist – so this does not really support Open RAN system interoperability goals. On the positive side, CPRI can be seen as the genesis of split 7 and it is an interface used by the O-RAN Alliance.
Security is a key requirement on all Open RAN initiatives; it is baked into all standards and there are specialist working groups in each of the standards bodies, including 3GPP, O-RAN Alliance and ETSI.
The following bodies are all developing key standards relating to open networks:
3GPP
The 3rd Generation Partnership Project (3GPP) is the global technical standards specifications initiative responsible for bringing together, producing and disseminating the Reports and Specifications that define 3GPP technologies, on behalf of seven national or regional telecommunications standard development organisations (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC).
The 3GPP’s focus is on delivering a minimum specification baseline for globally applicable cellular telecommunications technologies, including radio access, core network and service capabilities, to provide a complete system description for mobile telecommunications.
The 3GPP specifications are structured in releases; 5G NR (New Radio) was first introduced in Release 15, with the 5G end-to-end system in Release 16 and the current agreed work plan spans into Release 18 for 5G Advanced.
With regards to diversification, 3GPP has carried out work on the pros and cons of different logical and functional splits between network components.
O-RAN Alliance
This industry alliance, driving interoperable Open RAN standards, is widely recognised for its contribution in bringing together a global and thriving O-RAN ecosystem of operators, vendors and system integrators. It aims to collaboratively develop, promote and validate common Open RAN interoperability standards.
At its very core is the development and publication of the O-RAN specifications, which aim to remove some of the inevitable 3GPP standards ambiguities and develop common approaches that O-RAN certified solutions will follow, ensuring they can interoperate in multi-vendor integration environments.
The O-RAN Alliance is also instrumental in organising several O-RAN Plugfests, PoC’s (proof of concept) and Open Testing & Integration Centres (OTIC) around the world, to enable interoperability testing across the vendors. At this stage there is no OTIC lab in the UK. European OTIC labs are in Berlin, Madrid, Paris and Torino operated by BT, Telefonica, FT-Orange and TIM respectively.
The O-RAN Alliance provides 3 levels of certification, related to compliance of network elements to O-RAN standards:
- Certification of Conformance, tests a specific product or “device under test” (DUT) for conformance against the O-RAN interfaces or reference design specification
- Interoperability badge, provides a pair-wise interoperability assessment between two products (DUTs)
- End-to-end system integration badge, provides an assessment of end-to-end system integration of a group of products
The O-RAN Alliance has been influential in developing the “split 7” O-RAN disaggregation architecture, namely the two variants of the 7.2x fronthaul specification between the DU and RU, which lends itself particularly well to virtualisation and to a broad range of fronthaul connectivity options.
Founded by its initial five mobile operator members (AT&T, China Mobile, Deutsche Telekom, NTT DOCOMO and Orange) in 2018 only a few short years ago, the ORAN Alliance membership is now near ubiquitous across the global RAN ecosystem, with 31 operators and 345 companies in total.
Telecom Infra Project (TIP)
Was founded by Facebook (now Meta) as a community of telecoms network industry players to foster a collaborative ecosystem approach to accelerate the development and adoption of open, disaggregated, standards-based networks with an initial focus on developing for underserved markets.
TIP’s scope spans radio access, transport, core and services; most notable has been TIP’s championing of Open RAN and open virtualised software-based network infrastructure platforms.
Early ecosystem engagement and impact was delivered by a number of plugfest events. The development of “TIP Blueprints” and the establishment of 17 TIP Community Labs worldwide further builds on this momentum to collaboratively test and deploy open disaggregated networks; two such labs are based in the UK:
- London, UK, sponsored by Facebook
- Adastral Park, Ipswich, UK, sponsored by BT
TIP’s Test & Validation programme provides three levels of ‘badges’ and two levels of ‘ribbons’, depending on the maturity of the solution, who tested it and in which lab.
Vodafone and Telefonica are both notable for their strong and early level of engagement with TIP; they have worked with TIP to attract and engage tech suppliers and integrators, formulate and run RFI activities, share information and carry out integration design and integration testing in labs and plugfests.
The O-RAN Alliance and TIP in 2020 announced a liaison agreement, that aims to ensure further alignment in the development of interoperable open RAN solutions.
The Small Cell Forum
is taking a strong leadership role in some key aspects, including the use of FAPI specifications in Open RAN and also Neutral Host small cell networks.
In many ways the small cells ecosystem was a predecessor to the Open RAN industry today, in that it was made up of several small software and hardware vendors each focusing on a specific component, and complex system integration was often required to bring together the complete small cell end-to-end solution.
The market soon decided it was important to agree a number of common interfaces to foster interoperability, innovation, competition, as well as reduce barriers to entry to new suppliers. The Small Cell Forum was the industry body that undertook to coordinate the development of open APIs for small cells, which took the form of the FAPI suite of interface specifications. The latest of these continue to be very relevant to the Open RAN ecosystem today. The functional “split 6” disaggregated architecture is adopted and developed by SCF in the 5G nFAPI specifications as it is particularly relevant to the virtualisation of small cell deployments.
Representation of UK industry stakeholders in the SCF is very high. The SCF can therefore be seen as an example of how a home-grown UK ecosystem can steer a global industry body; the UK is often ahead of the market in incubation and adoption of small cell and neutral hosting technologies and business models. UK stakeholders are already leveraging the global reach of the small cell forum to create global engagement and influence.
Joint Operators Technical Specification (JOTS)
The Joint Operators Technical Specifications (JOTS) forum publishes technical specifications that enable mobile operators and their vendor or neutral host partners to deploy common, shared radio network infrastructures. These shared radio networks are often found in stadiums, shopping centres, public transport settings and increasingly in office buildings.
Although JOTS has a purely UK focus, it has managed to engage numerous global tech suppliers to collaboratively design and test common standard architectures for shared mobile networks. Strong engagement by all UK MNOs means it is seen by some as a necessary check-box for UK MNO shared network business.
Historically, JOTS has mostly focused on delivering a Distributed Antenna System specification and extending this from its 2G origin to span 3G, 4G and 5G. More recently, the JOTS NHIB (Neutral Host In-Building) specification stands out as a pioneering UK initiative that has culminated in a detailed five-part, commonly agreed, open 4G/5G small cell architecture for neutral host solutions to securely connect to all four UK MNO core networks and can serve the subscribers of all four UK MNOs. It is intended to streamline and reduce the cost and complexity of multi-operator small cell deployment and is well suited to an open RAN approach.
The NHIB specification goes well beyond simply defining common interfaces and radio performance requirements in that it contains details spanning:
- Architecture
- Radio Requirements
- Test and Acceptance
- Operational Processes
- Fulfilment
JOTS is specifically excluded from looking at anything commercial, for competition regulation reasons, and has no remit to ensure that any of the technical solutions it designs or approves would ever find a market beyond the UK. Having said this, several international operators, technology vendors, neutral hosts and industry standards organisations have shown great interest in leveraging this initiative beyond the UK.
