Xn Handover (Xn-based Handover)

Xn handover is the 5G inter-gNB mobility procedure (3GPP TS 38.423) where source and target gNBs coordinate directly over the Xn interface without AMF path-switch until the final step. It reduces latency compared to N2-based handover and preserves the security context by deriving a new KgNB via horizontal or vertical key derivation using the NH parameter.

Categories: Radio Access NetworkEncryption and Cryptography

Xn Handover in context

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

Cryptography in telecom spans air-interface ciphers (A5/1, A5/3, ZUC, SNOW, NEA/NIA), transport (IPsec, TLS) and identity (AKA, 5G-AKA, EAP-AKA'). Weak or downgradeable ciphers remain a live risk on 2G/3G fallback.

To place Xn Handover in the wider telecom-security picture, review XnAP, MACsec, Private 5G, SIR, SRVCC and N2 Handover: each entry cross-references back to this page so you can walk the topic in either direction.

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