An xApp is a software tool used by a RAN Intelligent Controller (RIC) to manage network functions in near-real time.
xApps are part of a RIC — a central software component of the Open RAN architecture. It is responsible for controlling and optimizing RAN functions and resources. There are two types of RIC. One operates from within the Service and Management Orchestration (SMO) framework, centrally on the operator’s network. It handles non-real time (non-RT) events. The other, a near-real time (near-RT) RIC, operates as a cloud-based process on the network edge.
A RIC is part of a virtualized RAN (vRAN) strategy. RAN operations go from proprietary hardware to scalable, flexible, continuously upgradable software functions. Disaggregating RAN functions is key for operators to achieve the flexibility and scale they need to pivot to new 5G services.
The near-RT RIC operates as a cloud-based process on the network edge. It handles events requiring action from 10 milliseconds (ms) to 1 second. The near-RT RIC provides policy guidance back to the non-RT RIC through xApps.
xApps operate in near real time
The near-RT RIC hosts cloud-native, microservice-based applications referred to as xApps. They exist to continuously enhance the RAN’s spectrum efficiency. The platform manages a distributed collection of “southbound” RAN functions. It also provides “northbound” interfaces for operators: The A1 and O1 interfaces to the Non-RT RIC for the management and optimization of the RAN.
This enables the RIC to self-optimize across different RAN types, like macros, Massive MIMO and small cells. The near-RT RIC maximizes network resource utilization — crucial for successful 5G network scaling.
Within the structure of the near-RT RIC itself, xApps communicate via defined interface channels. There’s an internal messaging infrastructure. It provides the framework to handle conflict mitigation, subscription management, app lifecycle management functions and security. Data flows via the RIC’s E2 interface.
Nokia and AT&T successfully tested a RIC configuration on the carrier’s mmWave 5G network in early 2020. Measurement and optimization xApps collected live network data during the trial.
Intel and VMware first announced a partnership in 2020 to work together on a RIC solution, and VMware RAN Intelligent Controller is the result. The software uses Intel’s FlexRAN reference architecture and is based on a specifications developed by the O-RAN Alliance. VMware anticipates releasing it early in 2022.
