FAQ    

 

 

What are the types of Interfaces defined in OpenRAN ?

In the OpenRAN architecture, there are several key interfaces defined to facilitate communication and interoperability between different components of the radio access network (RAN). These interfaces are critical for enabling the modular and flexible design principles that OpenRAN promotes. Here's an overview of the major types of interfaces:

A1 Interface

The A1 interface connects the Non-Real-Time RIC (Radio Intelligent Controller) with the Near-Real-Time RIC. It is primarily used for exchanging policy and control information, enabling the Non-Real-Time RIC to influence RAN optimization strategies implemented by the Near-Real-Time RIC.

  • Between: Non-Real-Time RIC and Near-Real-Time RIC.
    • Non-Real-Time RIC: Handles long-term analytics and policy management.
    • Near-Real-Time RIC: Executes policies and optimizations in near-real-time.
  • Purpose: Exchanges policy and control information for RAN optimization.
    • Allows dynamic adjustment of RAN behavior.
    • Supports AI/ML-driven policy enforcement.

E2 Interface

The E2 interface facilitates communication between the Near-Real-Time RIC and various RAN nodes such as O-CU-CP, O-DU, and O-RU. It enables near-real-time control and optimization of the RAN by allowing the RIC to monitor and manage these network elements.

  • Between: Near-Real-Time RIC and RAN nodes (O-CU-CP, O-DU, O-RU).
    • O-CU-CP: Central Unit - Control Plane.
    • O-DU: Distributed Unit.
    • O-RU: Radio Unit.
  • Purpose: Enables near-real-time RAN control and optimization.
    • Monitors RAN performance metrics.
    • Implements control actions for resource management.

O1 Interface

The O1 interface is used by the SMO (Service Management and Orchestration) framework to manage and orchestrate RAN components, including both RICs and other network elements. It supports functions such as configuration, fault management, and performance monitoring.

  • Between: SMO framework and RAN components including RICs.
    • SMO: Centralized management and orchestration platform.
    • RAN components: Includes RICs, O-DU, O-CU, O-RU, etc.
  • Purpose: Manages and orchestrates RAN elements and RIC functionalities.
    • Configuration management.
    • Fault detection and reporting.
    • Performance monitoring and analytics.

O2 Interface

The O2 interface connects the SMO framework with the Near-Real-Time RIC, focusing on the management and orchestration of Near-Real-Time RIC functions. It enables lifecycle management and resource allocation for RIC applications.

  • Between: SMO framework and the Near-Real-Time RIC.
    • SMO: Orchestrates RIC application deployment.
    • Near-Real-Time RIC: Hosts xApps for RAN optimization.
  • Purpose: Manages and orchestrates Near-Real-Time RIC functions.
    • Lifecycle management of xApps.
    • Resource allocation and scaling.

F1 Interface

The F1 interface links the O-CU-CP (Central Unit - Control Plane) with the O-DU (Distributed Unit). It is divided into F1-C for control plane signaling and F1-U for user plane data transfer, supporting the split architecture in 5G and OpenRAN deployments.

  • Between: O-CU-CP and O-DU.
    • O-CU-CP: Handles control signaling.
    • O-DU: Manages radio resources and scheduling.
  • Purpose: Split into F1-C for control plane and F1-U for user plane information transfer.
    • F1-C: Manages signaling and session control.
    • F1-U: Transfers user data packets.

E1 Interface

The E1 interface connects the O-CU-CP and O-CU-UP (Central Unit - User Plane). It is responsible for carrying control plane messages that manage user connections and sessions, ensuring coordination between control and user plane functions.

  • Between: O-CU-CP and O-CU-UP.
    • O-CU-CP: Controls session and mobility management.
    • O-CU-UP: Handles user data forwarding.
  • Purpose: Carries control plane messages for connection management through the user plane.
    • Session setup and release.
    • Mobility management coordination.

Further Readings