空口加密
NAS消息：Attach Request、PDN Connectivity Request
NAS消息：Attach Accept、Active Default EPS Bearer context Request
MME
RRC Connection Setup Complete
DL NAS Transfer
Initial Context Setup Response
Security Mode Command
UL NAS Transfer
UL Information Transfer
RRC Connection Request
UE Capability Information Indication
携带NAS消息的SRB1指令
UE
鉴权
NAS加密
RRC Connection Setup
RRC Connection Reconfiguration Complete
NAS消息：Attach Complete、Active Default EPS Bearer context
RRC Connection Reconfiguration
UE Capability Information
UE能力上报
UE Capability Enquiry
DL Information Transfer
Initial UE Message
Initial Context Setup Request
eNodeB
UL Informationn Transfer
建立UE上下文，进行SRB1资源准入与资源分配
