Deutsche Telekom started a live trial in Berlin to put the Open Networking Foundation’s (ONF) SD-RAN open radio access network (RAN) project to the test. ONF embarked on the open RAN space to better integrate and create interoperability across xApps and fuel the development of applications for the near real-time RAN intelligent controller (nRT-RIC).

These xApps are designed to control the RAN and house the most important functions required to give operators more administrative RAN sovereignty over functions that are typically implemented as proprietary features on base stations.

Deutshe Telekom’s trial in Berlin features disaggregated hardware spanning the radio units, distributed units (DU), and central units (CU), paired with open source nRT-RIC software and xApps developed under the SD-RAN project. 

The operator also deployed ONF’s SD-Core and SD-Fabric projects, which in combination with the SD-RAN project, form ONF’s broader Aether effort that recently coalesced into Ananki, a new corporate entity established to push Aether as a commercialized private 5G service.

“The key differentiator from other supplier RICs is ONF’s open, vendor-neutral framework, which is driven by operator use cases,” Alex Jinsung Choi, SVP of strategy and technology innovation at Deutsche Telekom, wrote in response to questions.

SD-RAN offers an open platform with O-RAN Alliance compliant interfaces that allows for a “higher degree of interoperability” with systems vendors and xApp suppliers, Choi added. 

Deutsche Telekom’s initial phase of the trial will focus on validating the architecture and interfaces to ensure xApp interoperability, according to Choi. He expects the trial to nudge RIC and xApps frameworks to production readiness, but notes it’s “still too early to consider mass-market deployment, as progress is still needed in a few critical areas.”

The trial includes deployed equipment from AirHop, Edgecore, Foxconn, Intel, Radisys, Supermicro, and Wiwynn, and the Facebook-led Telecom Infra Project (TIP) is providing hardware and facilities at its Berlin lab.

The deployment features a containerized CU from Radisys hosted by Aether and a Radisys DU hosted by Intel’s Smart Edge Open software toolkit for cloud-native deployment of RAN workloads and optimization on Intel processors and accelerator cards. The CU and DU are also integrated with ONF’s nRT-RIC, xApps, SD-Core’s 5G core, and open radio units from Foxconn.

“The operationalization of the multi-vendor setup in Berlin, based on ONF’s SD-RAN platform to power the outdoor trial, has been the first step successfully accomplished with the SD-RAN project partners,” Choi said. Three initial xApps from the ONF community are currently deployed in ONF’s nRT-RIC as part of the trial.

ONF’s nRT-RIC builds upon the ONOS SDN Controller, follows and adheres to the O-RAN Alliance’s architecture and vision, and ONF plans to contribute new functionalities and advancements back to the O-RAN Alliance, Choi explained.

“The multi-component disaggregated RAN architecture requires a high degree of automation,” he said. “The more suppliers that are introduced in a RAN environment, the higher the interoperability testing complexity. We need automation on all operational levels, including the adoption of automated testing processes.”

While ONF’s existing test frameworks and tools are currently automating the testing of software, the testing of hardware-based deployments “still need to be enhanced to enable a much higher level of automation,” Choi explained. 

Deutsche Telekom intends to further develop specialized use cases for the initial xApps and service models running in the trial and develop more applications based on ONF’s nRT-RIC, according to Choi.

“We expect that these advancements will provide us with the opportunity to gradually expand the Berlin SD-RAN setup, and ensure the readiness of the solution for field trials at larger scale,” he said.