The full potential of 5G cannot be reached until operators implement the Standalone version of the 5G New Radio standards, which involves implementing a virtualized, and preferably cloud-native, core network – the part that connects their radio access network (RAN) to their internal applications and the wider internet. Until operators have this core, their initial 5G NR Non-Standalone rollouts, which rely on a slightly updated LTE core, will deliver little more than 4G++.
Deploying the new core will be no mean task, however, which is why every MNO with plans to launch 5G in 2019 or 2020 has opted for the simpler first step of Non-Standalone. And while a few will start to deploy the 5G core next year, the majority – according to Rethink’s operator surveys – indicate they will start the process in 2022 or later. Of course, many operators will not deploy 5G at all until that year, or a lot later, and increasingly they will be able to move straight to Standalone mode, as the 5G core becomes more mature and deployable.
The three big challenges of the 5G core migration:
For the next few years, though, those which are brave enough to take the plunge early will face challenges on three fronts:
- The 5G Core Network (5GCN) is a completely different architecture from the 5G Evolved Packet Core (EPC), so the migration will be a significant effort, as will decisions about interoperating with the 4G platforms, which will stay in action for many years in most cases.
- To support the maximum flexibility, cost-effectiveness and programmability, the core needs to be cloud-native and containerized, which will enhance its ability to support dynamic slicing and new user experiences. However, this entails an operator taking on board new skills and expertise, as well as new technologies – for instance, introducing cloud approaches like DevOps to an organization accustomed to very different processes.
- Many operators want the core to be multivendor, in order to be able to select the most innovative elements and avoid lock-in. That means buying a core that may not come from the same vendor as the RAN, and being able to mix and match different core elements, virtual network functions and microservices, from different suppliers, on a common platform.
None of the vendors, nor the open initiatives such as Open Networking Foundation, has a cloud-native, multivendor 5GCN solution yet, that is fully deployable for the main core, at proven commercial carrier-grade robustness. Operators will engage in many more trials before they gain that level of confidence in any offering, and the earliest movers say they will invest a lot in inhouse integration and customization to bring commercial offerings up to scratch.
Samsung, HPE and Openet demonstrate multivendor cloud-native core:
But big leaps forward are being made, by the major OEMs and particularly by innovative specialists such as Mavenir and Affirmed Networks. An interesting partnership was announced last week, by Samsung – keenly chasing an enhanced role in mobile networks by leveraging open technologies and new alliances. The Korean vendor is working with enterprise giant HPE and Irish PCRF (policy and charging rules function) supplier Openet.
The three companies have demonstrated multivendor interoperability between their various VNFs in a Samsung 5G Standalone Core environment. The demo showed the core being used to support network slicing with dynamic policy and charging rules for different use cases.
The VNFs contributed by Samsung included access and mobility management, session management, user plane, network repository, and network slice selection functions. HPE’s VNFs included its unstructured data storage, unified data repository, authentication server, unified data management, and network exposure functions. And Openet added its policy control, binding support, and charging functions.
“5G SA Core built on open architecture is a key driver of the innovative services that 5G promises, and it will help mobile operators create new revenue streams and business opportunities,” said Wonil Roh, head of product strategy for Samsung’s Networks Business, in a statement. Samsung will now offer demonstrations of the SA Core solution remotely, or on-site at its 5G Core Open Lab in Korea.
Operators insist on multiple suppliers, despite barriers:
While vendors are starting to work together on multivendor core functionality, a few operators have also discussed trials of multivendor cloud cores. Notable among these are NTT Docomo of Japan and SK Telecom of Korea (though both these were achieved with a great deal of inhouse and customized work, at a cost and complexity that would not work for the majority of MNOs). Still more operators have set out their determination to be multivendor, even if this makes implementation of the new core far harder than a single-vendor solution would be.
Enrique Blanco, Telefónica’s CTO, told the recent 5G Core Summit in Madrid that he was determined to deploy a multivendor 5G core, even though that will add to the already daunting complexities of the migration.
He acknowledged that it would be “easier and cheaper” to work with just one vendor, but this would increase many risks, including those related to security and to potential outages. “It is easier to do with a single vendor in a single core, but we are doing a different approach to guarantee there is not any problem that can go viral and affect all customers. The industry needs to help us do this.”
His roadmap includes full separation of the control and user planes, and a three-year transition to a microservices architecture. To support guaranteed service availability, he plans to deploy a multi-layered core, with each layer supporting a different service domain, and potentially a different region. Different suppliers could be engaged to provide the functions for one or more layers and/or regions.
This very complex approach will either require a huge and costly investment in integration (inhouse teams or via a partner), or it needs open platforms to evolve quickly so Telefónica can stitch together its core using standard interfaces supported by all suppliers. The early movers, SKT and Docomo, are using a mixture of open and inhouse interfaces and APIs, which they require any supplier of VNFs to support, in order to deploy VNFs from more than one vendor in the core. But they acknowledge they rely heavily on integration and developer skills to optimize the platforms and make them carrier-grade – something BT has also discussed with regard to cloud-based deployments.
Blanco does not believe there is much time for the industry to get behind emerging open source and cloud-native technologies, which will greatly improve cost and deployability and reduce risk for MNOs.