F1AP Messages
F1AP carries signaling between the gNB-CU and gNB-DU in split gNB deployments.
Use this category for future CU-DU signaling references without mixing them into radio tutorial pages.
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All Messages in This Category
This is the full published list for the F1AP category. Use the filter section above for a narrower interactive view.
5G F1AP - F1 Setup Request
F1 Setup Request is the first F1AP procedure a gNB-DU sends after the F1-C transport association becomes operational so the gNB-CU can learn DU identity, served-cell configuration, DU-owned system information, and transport details before the F1 interface starts carrying normal traffic.
5G F1AP - F1 Setup Response
F1 Setup Response is the successful outcome the gNB-CU returns after accepting F1 Setup, making the F1 interface operational and optionally instructing the gNB-DU which cells to activate, which PLMNs or SNPN IDs to broadcast, and which CU-owned system information or IAB-related data to store.
5G F1AP - UE Context Modification Failure
UE Context Modification Failure is the F1AP unsuccessful outcome the gNB-DU sends when a UE Context Modification Request cannot be accepted at procedure level, meaning none of the requested UE-context changes can be successfully performed or an essential mobility or SpCell condition makes the request invalid for execution.
5G F1AP - UE Context Modification Request
UE Context Modification Request is the UE-associated F1AP message the gNB-CU sends to the gNB-DU to change an already established UE context by adding, modifying, or releasing SRBs, DRBs, SCells, relay channels, multicast resources, or sidelink resources, updating CU-to-DU RRC information, and optionally stopping or restarting transmission for mobility before the DU replies with UE Context Modification Response or UE Context Modification Failure.
5G F1AP - UE Context Modification Response
UE Context Modification Response is the successful outcome the gNB-DU returns after applying an F1AP UE Context Modification Request, confirming which requested SRBs, DRBs, SCells, relay channels, multicast resources, or sidelink resources were established or modified successfully, which ones failed, what DU-to-CU RRC information the CU must use next, and which mobility or transmission-control related results such as Requested Target Cell ID, C-RNTI, or SCG Activation Status were produced.
5G F1AP - UE Context Release Command
UE Context Release Command is the UE-associated F1AP message the gNB-CU sends to the gNB-DU to order release of the UE-associated logical F1 connection and its related signaling and user-plane resources, or to cancel prepared conditional mobility, CPAC, or LTM-related cells for that UE, optionally carrying an RRC release payload, duplication execution, CG-SDT keep indication, positioning-context reservation, or paging-assistance requests before the DU answers with UE Context Release Complete.
5G F1AP - UE Context Release Complete
UE Context Release Complete is the successful outcome the gNB-DU sends after handling a UE Context Release Command, confirming that the requested UE-associated F1 context release or conditional-resource cancellation has been executed and optionally returning Criticality Diagnostics or Recommended SSBs for Paging List that the gNB-CU may store for later paging assistance.
5G F1AP - UE Context Setup Request
UE Context Setup Request is the UE-associated F1AP message the gNB-CU sends to the gNB-DU to create a UE context, nominate the SpCell, transfer CU-to-DU RRC content, and request setup of SRBs, DRBs, and optional IAB, relay, sidelink, multicast, or mobility-related resources before the DU replies with UE Context Setup Response or UE Context Setup Failure.
5G F1AP - UE Context Setup Response
UE Context Setup Response is the successful outcome the gNB-DU returns after establishing the requested UE context, confirming the DU-side UE association, returning DU-to-CU RRC information, providing downlink F1-U tunnel endpoints for successful DRBs, and reporting which requested SRBs, DRBs, SCells, BH RLC channels, relay channels, or multicast resources succeeded or failed to set up.