Section: 4.4.2 MME
Content: MME functions include: - 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, execution of paging retransmission and optionally Paging Policy Differentiation); - Tracking Area list management; - Mapping from UE location (e.g. TAI) to time zone, and signalling a UE time zone change associated with mobility, - 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 eNodeB); - UE Reachability procedures; - Support Relaying function (RN Attach/Detach); - Change of UE presence in Presence Reporting Area reporting upon PCC request, - in the case of Change of UE presence in Presence Reporting Area reporting, management of Core Network pre-configured Presence Reporting Areas. - For the Control Plane CIoT EPS Optimisation: a) transport of user data (IP, Non-IP and Ethernet)); b) local Mobility Anchor point; c) header compression (for IP user data); d) ciphering and integrity protection of user data; e) Lawful Interception of user traffic not transported via the Serving GW (e.g. traffic using T6a). NOTE: The Serving GW and the MME may be implemented in one physical node or separated physical nodes. For CIoT EPS Optimisation, the Serving GW and the MME can be implemented in one physical node (e.g. C-SGN) or separated physical nodes. The C-SGN can also encompass the PDN GW function. The MME shall signal a change in UE Time Zone only in the case of mobility and in the case of UE triggered Service Request, PDN Disconnection and UE Detach. If the MME cannot determine whether the UE Time Zone has changed (e.g. the UE Time Zone is not sent by the old MME during MME relocation), the MME should not signal a change in UE Time Zone. A change in UE Time Zone caused by a regulatory mandated time change (e.g. daylight saving time or summer time change) shall not trigger the MME to initiate signalling procedures due to the actual change. Instead the MME shall wait for the UE's next mobility event or Service Request procedure and then use these procedures to update the UE Time Zone information in the PDN GW.