O-RAN interfaces: A1, E2, O1, O2, open fronthaul

A1 and E2: The Intelligence Interfaces

O-RAN defines five standardized interfaces that enable the open architecture. The A1 interface connects non-RT RIC to near-RT RIC using RESTful APIs over HTTP/JSON for policy management, enrichment information delivery, and ML model deployment. The E2 interface connects near-RT RIC to O-CU and O-DU using E2AP protocol over SCTP for real-time control. E2 Service Models define available data and actions: KPM for metrics subscription, RC for control actions like handover, NI for network interface monitoring, and CCC for cell configuration changes.