S1 release procedure

日志

• 流程触发本质原因: 信令连接丢失, 触发eNodeB和MME本地执行流程
  
  • loss of the signalling transport
  • failure of eNodeB or MME
• 流程的发起者
  
  • eNodeB-initiated with cause e.g. O&M Intervention(干扰), Unspecified Failure(未指明错误), User Inactivity(用户不活动), Repeated RRC signalling Integrity Check Failure(重复RRC信令完整性校验失败), Release due to UE generated signalling connection release(UE发起释放信令连接请求), CS Fallback triggered(??), Inter-RAT Redirection(跨RAT重定向, e.g. 切换), etc. as defined in TS 36.413 [36]; or
  • MME-initiated with cause e.g. authentication failure(认证失败), detach(去附着), not allowed CSG cell(CSG 错误) (e.g. the CSG ID of the currently used CSG cell expires or is removed from the CSG subscription data), etc.

用户不活动
UE发起释放信令连接请求
跨RAT重定向(切换)
认证失败
去附着

• 做了那些事
  
  • SGW删除与UE相关eNodeB地址信息, 但保留上下文
  • MME释放S1连接, 但保留S1-U接口SGW端的地址和TEID
  • UE从ECM-CONNECTED状态转移到ECM-IDLE状态
  • 删除eNodeB上所有与UE相关的context information, 删除无线承载