We have recently analyzed how Nokia is seeking to lead development of a key new element of the O-RAN architecture, the RAN Intelligent Controller (RIC). With the RIC – which sits between the baseband and the orchestration layer in O-RAN’s vision of a disaggregated, virtualized network – the Alliance is proposing more than just common, open fronthaul interfaces to replace the semi-proprietary CPRI, and is eyeing full architecture changes.
Nokia has set aside some of the clear conflicts of interest involved in supporting open, multivendor platforms and has opened up its interfaces in some cases (notably for Rakuten), and is also contributing significantly to the code and the real world testing for O-RAN specifications, including the fronthaul and the RIC.
The gamble is, presumably, that many operators will adopt O-RAN, and Nokia will be the biggest and most credible vendor with a fully-developed solution at the ready. That could help it to steal back 5G market share recently lost to Ericsson and Huawei, while having the open credentials to fend off new challengers, from start-ups to Samsung and NEC.
The Finnish company has taken a step towards the goal of being first to offer a macro-scale, fully carrier-grade RIC, by announcing a successful test of the technology within AT&T’s commercial millimeter wave 5G network in New York. This provided improvements in network performance and efficiency by using the RIC combined with several specialized control apps, and machine learning, all running on AT&T’s Akraino edge cloud (see below for more details).
The demonstration started in February and is said to be an important proof point for AT&T’s CTO, Andre Fuetsch – also chair of the O-RAN Alliance – as he seeks to push through adoption of open platforms from SDN to virtualized RAN and core (in the face of some inevitable internal opposition from those who are concerned that openness will bring compromises in terms of performance, especially in the demanding functions of the RAN – the last element on AT&T’s virtualization roadmap).
In January 2019, AT&T and Nokia signed a multiyear co-development agreement to expand Akraino Edge Stack capabilities to support the RIC and other platforms which run at the edge – the RAN is the key focus because of its low latency requirements and the demanding nature of its digital signal processing. In many environments, that makes it poorly suited to be run entirely in a centralized cloud or on commoditized hardware. Instead, an edge node with souped-up processing capabilities courtesy of multiple accelerators can support carrier-grade performance and response, and a distributed architecture in which the RIC could potentially play a starring role.
The RIC could “enable dedicated network slicing and RAN optimization, while multi-access edge computing (MEC) could deliver ultra-low latency and allow critical content to be processed locally,” wrote Michael Clever, head of Cloud-RAN edge cloud platforms at Nokia, in a blog post.
The RIC is based on code from various sources, but the seed code, and much of the concept, came from Nokia. In O-RAN terms, it provides intelligence and control for the baseband layers, connecting to them via the O-RAN E2 interface, and including functions like 5G slicing. That makes it, potentially, a location for the ‘brain’ of the open 5G network to sit, weighting a significant amount of the intelligence for slicing and quality of service assurance close to the RAN, rather than in higher orchestration layers (coordination with those layers will be important, as the ONAP work to integrate with O-RAN shows – see separate item).
In turn, if the RIC becomes a widely adopted concept, it provides a source of power for its supplier, and plays to the strengths of RAN specialists, even though vendors from other domains, such as Cisco and Juniper, also see the RIC as potential path into the RAN.
The RIC comes in non-real time and near-real time configurations. It receives a request from an orchestrator, network management system or slicing engine and implements that request to the RAN; and can also be the location for self-optimising networking (SON) and other RAN apps such as AI control and programmability.
As in any O-RAN system, the RIC should be able to control RANs from any vendor, and from multiple vendors at once; and support orchestrators, control apps and tools from different suppliers on a common platform. But as already seen in other parts of the supposedly open network, large vendors can sometimes embrace the new specifications, while creating single-stack offerings that seem safer and easier for operators to deploy, and which are wrapped up in vendor-specific add-ons and services. The ‘white box’ routers showed the way – those in which Cisco or Juniper software is disaggregated from the hardware, but all the elements still come from the one supplier and are significantly optimized for one another.
That may be Nokia’s strategy, though it still carries risks. Rakuten CTO Tareq Amin praised the vendor for taking the bold step of opening up its interfaces so its radio would work with third party RAN software and core networks. But that did not prevent Rakuten replacing Nokia with NEC when it came to the 5G radio, something that would have been harder to do with a closed architecture.
The AT&T RIC trial:
The trial demonstrated a working implementation, jointly created by AT&T and Nokia, of the O-RAN RIC and the E2 interface. It allowed Nokia and third party applications to manage some network processes, running at the network edge on the AT&T-supported Akraino open edge cloud platform.
The RIC allows external applications, called xApps, to “control parts of the 4G and 5G radio network much faster than is currently possible through installed control applications”, wrote Nokia’s Clever, in a blog post. Benefits include faster addition of new services and access to innovations from multiple developers – a practice which Nokia has been more willing to embrace than its major rivals for some years. That is demonstrated by the early support of its SON platform, based on its Eden Rock acquisition, for operator requests to add third party use cases, or develop their own.
Clever said the RIC also improves spectral efficiency and network capacity because of more intelligent traffic management, which can be done in near-real time for QoS-critical or low latency applications. In the blog, he gave the example of xApps using machine learning to drive more intelligent traffic steering across different layers and radio access technologies.
“Meanwhile, localized and use case-based customization and rapid on-boarding of features will help to offer a far superior customer experience,” he wrote.
Nokia said the test achieved its goals. “Both companies tested the RAN E2 interface and xApp management and control, collected live network data using the Measurement Campaign xApp, the neighbor relation management using Automated Neighbor Relation (ANR) xApp, and tested RAN control via the Admission Control xApp – all with zero interruption to the live commercial network,,” it said in a statement.