参考资料：3Gpp 38.473
我就是个协议的搬运工~~~
1. F1AP服务
F1AP提供gNB-CU节点与gNB-DU节点之间的信令服务。服务分为两类：
- 非UE相关服务：在gNB-CU与gNB-DU之间建立F1接口实例。
- UE相关服务：为UE接入核心网提供信令和数据连接。
2. F1AP一般过程分类
（1）F1AP一般过程按是否有响应，可分为两类：
- Class 1：应答类消息，需要等待响应消息。
| 一般过程 | 发起消息 | 成功响应 | 失败响应 |
|---|---|---|---|
| F1 Setup | F1 SETUP REQUEST | F1 SETUP RESPONSE | F1 SETUP FAILURE |
| Reset | RESET | RESET ACKNOWLEDGE | |
| gNB-DU Configuration Update | GNB-DU CONFIGURATION UPDATE | GNB-DU CONFIGURATION UPDATE ACKNOWLEDGE | GNB-DU CONFIGURATION UPDATE FAILURE |
| gNB-CU Configuration Update | GNB-CU CONFIGURATION UPDATE | GNB-CU CONFIGURATION UPDATE ACKNOWLEDGE | GNB-CU CONFIGURATION UPDATE FAILURE |
| UE Context Setup | UE CONTEXT SETUP REQUEST | UE CONTEXT SETUP RESPONSE | UE CONTEXT SETUP FAILURE |
| UE Context Release (gNB-CU initiated) | UE CONTEXT RELEASE COMMAND | UE CONTEXT RELEASE COMPLETE | |
| UE Context Modification (gNB-CU initiated) | UE CONTEXT MODIFICATION REQUEST | UE CONTEXT MODIFICATION RESPONSE | UE CONTEXT MODIFICATION FAILURE |
| UE Context Modification Required (gNB-DU initiated) | UE CONTEXT MODIFICATION REQUIRED | UE CONTEXT MODIFICATION CONFIRM | UE CONTEXT MODIFICATION REFUSE |
| Write-Replace Warning | WRITE-REPLACE WARNING REQUEST | WRITE-REPLACE WARNING RESPONSE | |
| PWS Cancel | PWS CANCEL REQUEST | PWS CANCEL RESPONSE | |
| GNB-DU RESOURCE COORDINATION | GNB-DU RESOURCE COORDINATION REQUEST | GNB-DU RESOURCE COORDINATION RESPONSE |
- Class 2：通知类消息，无响应消息。
| 一般过程 | 消息 | 作用 |
|---|---|---|
| UE Context Release Request (gNB-DU initiated) | UE CONTEXT RELEASE REQUEST | |
| Initial UL RRC Message Transfer | INITIAL UL RRC MESSAGE TRANSFER | |
| DL RRC Message Transfer | DL RRC MESSAGE TRANSFER | |
| UL RRC Message Transfer | UL RRC MESSAGE TRANSFER | |
| UE Inactivity Notification | UE INACTIVITY NOTIFICATION | |
| System Information Delivery | SYSTEM INFORMATION DELIVERY COMMAND | |
| Paging | PAGING | |
| Notify | NOTIFY | |
| Error Indication | ERROR INDICATION | |
| PWS Restart Indication | PWS RESTART INDICATION | |
| PWS Failure Indication | PWS FAILURE INDICATION | |
| gNB-DU Status Indication | GNB-DU STATUS INDICATION | |
| RRC Delivery Report | RRC DELIVERY REPORT |
（2）F1AP一般过程按功能分类，大致可以分为以下6类：
| 功能 | 过程 |
|---|---|
| 接口管理 | Reset F1 Setup Error Indication gNB-DU Configuration Update gNB-CU Configuration Update gNB-DU Resource Coordination gNB-DU Status Indication |
| UE上下文管理 | UE Context Setup UE Context Release Request (gNB-DU initiated) UE Context Release (gNB-CU initiated) UE Context Modification (gNB-CU initiated) UE Context Modification Required (gNB-DU initiated) UE Inactivity Notification Notify |
| RRC消息转发 | Initial UL RRC Message Transfer DL RRC Message Transfer UL RRC Message Transfer RRC Delivery Report |
| 告警消息 | Write-Replace Warning PWS Cancel PWS Restart Indication PWS Failure Indication |
| 系统消息 | System Information Delivery |
| 寻呼 | Paging |