Specialized software apps for network automation, xApps and rApps are part of a RIC, an intelligent radio access network controller (RAN).
The functions of the RIC software interact with the Radio Unit (RU) hardware to maintain maximum optimization and efficiency of the RAN. RIC is an essential software component of the Open RAN architecture specified by the O-RAN Alliance. Check and optimize the radio functions. The RIC separately checks for non-real-time (non-RT) events – from 10 milliseconds to 1 second – and near-real-time (near-RT) events – more than 1 second.
RIC is a key element in managing advanced 5G network functions, such as network slicing, high-bandwidth, low-latency applications, priority communications, and more. Its architecture includes a Distributed Unit (DU) software function, multi-RAT CU protocol stack, a near real-time RIC, and an orchestration / NMS layer with non-real-time RIC.
xApps and rApps are network automation tools. They maximize the operational efficiency of the radio network. RApps are specialized microservices operating on the non-RT RIC. xApps and rApps provide essential control and management functionality and functionality. The xApps are hosted on the nearby RT RIC and optimize the efficiency of the radio spectrum.
The characteristics and functionalities of the RIC – and of the RAN breakdown in general – are explained in version 15 of 3GPP. The O-RAN Alliance manages several technical working groups responsible for modeling different elements of the Open RAN specification.
The guidelines for the RIC specification falls under the auspices of Working Groups 2 and 3 O-RAN. These are intelligent non-real-time RAN controller and A1 interface working group and near real-time RIC and E2 interface working group respectively.
rApps: non-real-time network automation
The non-RT RIC operates within the RIC’s Service Management and Orchestration (SMO) framework. This software runs centrally on the operator’s network. The non-RT RIC communicates with the RIC counterpart applications near RT, called xApps, to provide policy-based guidance.
SMO supports open software interfaces to facilitate rApp communications. This open design prevents RAN software vendors from blocking network functionality. Operators can and should continually update and optimize network automation software as part of a DevOps process.
Ericsson’s intelligent automation platform is an implementation of an open SMO RAN. Using Artificial Intelligence (AI) and Machine Learning (ML), network automation software constantly adjusts RAN operations to manage and optimize network conditions. It provides the key automation tools that operators need to effectively scale digitized RAN operations in a cloud-native environment.
The xApps work almost in real time
The near-RT RIC handles those events that require an action from 10 milliseconds (ms) to 1 second. Near-RT RC works as a cloud-based process at the edge of the network. Provides guidance on the criteria for returning to non-RT RIC via xApps. There are xApps to continuously improve the spectrum efficiency of the RAN.
Within the near-RT RIC structure itself, xApps communicate via defined interface channels. There is an internal messaging infrastructure. Provides the framework for managing conflict mitigation, subscription management, app lifecycle management functions, and security. Data flows through the RIC’s E2 interface for other network automation policy functions.
Nokia and AT&T successfully tested a RIC configuration on the carrier’s 5G mmWave network in early 2020. The measurement and optimization xApps collected real-time network data during the trial period.
VMware’s intelligent RAN controller incorporates both non-RT and quasi-RT functions. The software uses Intel’s FlexRAN reference architecture and is based on specifications developed by the O-RAN Alliance. VMware plans to release it in early 2022.