LTE系统全网信令流程幻灯片.ppt

LTE系统全网信令流程 Abbreviations Network elements functions eNodeB functions: - Header compression and user plane ciphering; - MME selection when no routeing to an MME can be determined from the information provided by the UE; - UL bearer level rate enforcement based on UE-AMBR and MBR via means of uplink scheduling(e.g. by limiting the amount of UL resources granted per UE over time); - DL bearer level rate enforcement based on UE-AMBR; - UL and DL bearer level admission control; - Transport level packet marking in the uplink, e.g. setting the DiffServ Code Point, based on the QCI of the associated EPS bearer. MME functions: - NAS signalling; - NAS signalling security; - Inter CN node signalling for mobility between 3GPP access networks (terminating S3); - UE Reachability in ECM-IDLE state (including control and execution of paging retransmission); - Tracking Area list management; - PDN GW and Serving GW selection; - MME selection for handovers with MME change; - SGSN selection for handovers to 2G or 3G 3GPP access networks; - Roaming (S6a towards home HSS); - Authentication; - Authorization; - Bearer management functions including dedicated bearer establishment; - Lawful Interception of signalling traffic; - Warning message transfer function (including selection of appropriate eNB); UE Reachability procedures. SGSN functions: - Inter EPC node signalling for mobility between 2G/3G and E-UTRAN 3GPP access networks; - PDN and Serving GW selection: the selection of S?GW/P?GW by the SGSN is as specified for the MME; MME selection for handovers to E-UTRAN 3GPP access network. Network elements functions Serving GW functions: - the local Mobility Anchor point for inter-eNodeB handover; - sending of one or more end marker to the source eNodeB, source SGSN or source RNC immediately after switching the path during inter-eNodeB and inter-RAT handover, especially to assist the reordering function in eNodeB. - Mobility anchoring for inter-3GPP mobility (terminating S4 and relayin