AN 释放流程

sequenceDiagram participant UE participant gNB participant AMF participant SMF participant UPF gNB->>AMF: ① UE Context Release Request(Cause:user inactivity) AMF->>SMF: ② Nsmf: UpdateSMContext(UP deactivated) SMF->>UPF: ③ N4 Modification(FAR改为Buffer+通知) AMF->>gNB: ④ UE Context Release Command gNB-->>AMF: ⑤ UE Context Release Complete Note over UE: 进入CM-IDLE，空口/N2/N3释放 Note over UPF: 下行数据到达时缓存并通知SMF