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:
- Between: Non-Real-Time RIC and Near-Real-Time RIC.
- Purpose: Exchanges policy and control information for RAN optimization.
E2 Interface:
- Between: Near-Real-Time RIC and RAN nodes (O-CU-CP, O-DU, O-RU).
- Purpose: Enables near-real-time RAN control and optimization.
O1 Interface:
- Between: SMO framework and RAN components including RICs.
- Purpose: Manages and orchestrates RAN elements and RIC functionalities.
O2 Interface:
- Between: SMO framework and the Near-Real-Time RIC.
- Purpose: Manages and orchestrates Near-Real-Time RIC functions.
F1 Interface:
- Between: O-CU-CP and O-DU.
- Purpose: Split into F1-C for control plane and F1-U for user plane information transfer.
E1 Interface:
- Between: O-CU-CP and O-CU-UP.
- Purpose: Carries control plane messages for connection management through the user plane.