LTE典型信令过程.ppt

LTE 典型信令过程 Software Architecture 3类NAS信令流程 1. 会话管理相关 2. 位置管理相关 3. 鉴权管理相关 UE initiated Detach Procedure Network Triggered Service Request TAU procedure Inter MME-TAU-message flow Handover Handover Air Interface X2 Handover S1 Handover 开始 Before the UE can do anything, a Radio Resource Control connection must be established. The RRC is a logical connection between the UE and E-UTRAN. There are two different RRC states: RRC IDLE RRC CONNECTED RRC IDLE This state indicates that there is no signaling radio bearer is established i.e. no RRC connection is established. The UE is considered RRC_IDLE once it obtains the center frequency, reads the timing information, syncs to the eNodeB, and is ready to receive system broadcast information. UE monitors a paging channel to detect incoming calls. UE can performs neighboring cell measurements and measurement reporting. RRC CONNECTED This state indicates that there is signaling radio bearer established i.e. RRC connection is established. Transfer of unicast data to/from an UE. The UE Monitors control channels associated with the shared data channel to determine if data is scheduled for it. The UE Provides channel quality and feedback information. The UE Perform neighboring cell measurements and measurement reporting. Radio Resource Control (RRC) protocol states RRC_IDLE state vs. RRC_CONNECTED state: UE does not have context in eNB and only Signalling Radio Bearer 0 (SRB0) is available for signalling between eNB and UE. UE has context in eNB and communications between the UE and the network occurs on Signalling Radio Bearer 1 (SRB1) and Signalling Radio Bearer 2 (SRB2) UE generally has an id unique in the tracking area (S-TMSI = 40 bits long); UE generally has an id unique in the eNB area (C-RNTI = 40 bits long) UE may perform cell selection/reselection without involvement from eNB; UE can perform handover (inter-eNB, intra-eNB, inter-RAT) under eNB control; UE can request connection establishment or re-esta