MME function functions

MME is responsible for the following functions.

●NAS signaling and its security.

●Send paging messages to relevant eNBs, optionally performing paging optimization.

●Security control (authentication, signaling integrity protection and data encryption).

●Cross-CN signaling (supporting mobility between different 3GPP access networks).

●The reachability of UE in idle state (including control and execution of paging retransmission messages).

●Tracking area (TA) list management (idle state and active state UE).

●PDNGW (P-GW) and S-GW selection.

●MME selection when MME changes during handover.

●SGSN selection when switching to 2G or 3G access network.

●Roaming.

●Mobility control in idle state.

●Bearer management functions, including the establishment of dedicated bearers.

●Encryption and integrity protection of non-access layer signaling.

●Supports the sending of PWS (PublicWarningSystem, public security early warning system, including ETWS and CMAS) messages.