rApps manage non-real time events within the Radio Access Network (RAN) Intelligent Controller, or RIC
The RIC is a central software component of the Open RAN architecture. It is responsible for controlling and optimizing RAN functions. It’s part of a virtualized RAN (vRAN) strategy that disaggregates RAN operation into scalable, flexible, continuously upgradable software functions instead of proprietary and restrictive network hardware. Disaggregating RAN functions is key for operators to achieve the flexibility and scale they need to pivot to new 5G services.
The RIC manages non-real time (non-RT) and near-real time (near-RT) events separately. Non-RT events — event loops of 1 second or greater — are handled within the Service and Management Orchestration (SMO) layer, which functions centrally on the operator’s network. The non-RT RIC communicates with the near-RT RIC’s counterpart applications, called xApps, to provide policy-based guidance.
“The placement of the Non-RT RIC in the SMO and not in the RAN is to secure access to contextual data and use it to optimize the RAN, something that the RAN nodes CU, DU and Near RT-RIC can’t do. One example is the coordinated optimization of radio and transport to adjust user-level throughput based on application performance and contextual prioritization, which can’t be achieved in existing networks,” said Ericsson.
rApps connect to open interfaces
The SMO supports open software interfaces to facilitate rApp communications. This open design precludes individual RAN software vendors from locking down network features, as their products can easily be replaced with another app from another vendor.
“A standardized information model and the open interfaces A1, O1 and O2 makes it possible to have rAPPs from both incumbents, third parties and service providers alike, that together, can steer any RAN,” said Ericsson.
Near-RT events — those events requiring action from 10 milliseconds (ms) to 1 second — are managed by the near-RT RIC, which operates as a cloud-based process on the network edge. The near-RT RIC provides policy guidance back to the non-RT RIC through xApps.
“As a contrast, the CU-CP and the Near-RT RIC both act on the same 100 ms time scale which is a potential source of conflicts Non-RT RIC adds the ability to send optimization policies enrichment information targeting an individual user by adding the new A1 interface that complements the per-node configuration interface O1,” said Ericsson.
rApps in the real world
In October, the O-RAN Alliance published nine new Open RAN specifications including the Non-Real-Time RAN Intelligent Controller (RIC) Architecture. Another 39 technical documents have been established to extend and add features to the existing specifications.
VMware relied on Intel’s Open RAN-compliant FlexRAN reference architecture to develop VMware RAN Intelligent Controller, due out next year. VMware is hoping to stimulate xApp and rApp developer interest before the general VMware RIC release, which is expected to happen by next April. The new developer program will provide licenses, support, testing and interoperability certifications. VMware expects to release RIC Software Development Kits (SDKs) in January. VMware’s early RIC development partners including Cohere Technologies, Polte, AirHop and Cellwize.
Ericsson’s Intelligent Automation Platform was built on Open RAN specs. The platform optimizes operator RANs in 4G and 5G networks as they replace dedicated hardware with Virtual Network Functions (VNFs) and Cloud Native Functions (CNFs).
Intelligent Automation Platform is an implementation of an Open RAN SMO. Using Artificial Intelligence (AI) and Machine Learning (ML), the software constantly monitors an operator’s RAN to manage and optimize network conditions. It provides key automation tools operators need to effectively scale digitized RAN operations in a cloud-native environment.