O-CU (O-RAN Centralized Unit)

Also known as: O-RAN Centralized Unit, O-RAN Central Unit, O-CU-CP, O-CU-UP

The O-CU is the O-RAN Alliance's disaggregated 5G gNB Centralized Unit, split into O-CU-CP (control plane, RRC/PDCP-C) and O-CU-UP (user plane, PDCP-U/SDAP). It terminates the F1 interface toward the O-DU and the E1 interface between CP and UP. In Open RAN deployments the O-CU typically runs as a cloud-native workload on O-Cloud, so its hardening (workload isolation, TLS on F1/E1, image supply chain) is a WG11 security concern.

Categories: Radio Access NetworkInternet and Routing

O-CU in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Telecom networks depend on Internet-style routing (BGP, DNS, MPLS) for interconnect, transport and application delivery. Route hijacks and DNS abuse can degrade or intercept signaling as easily as any application-layer attack, which is why RPKI and DNSSEC are now standard hardening for carrier networks.

To place O-CU in the wider telecom-security picture, review O-DU, O-RU, O2 Interface, Open Fronthaul, O-Cloud and Satellite Backhaul.

Related terms

Equipment

O-RAN units and RIC (O-RU, O-DU, O-CU, RIC, SMO)

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