Mobility Management Entity (MME)

The Mobility Management Entity (MME) is the key control-node for the LTE access- network. It is controll all the signaling and  responsible for idle mode UE tracking and paging procedure including retransmissions.

Summary of MME function are describe as below :
 1. Authentication
MME responsible for authenticating the user by interacting with HSS through S6a Interface

2. Bearer management & SGW selection
MME is involved in the bearer activation/deactivation process and is also responsible for choosing the SGW for a UE at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation

3. Non -Access Stratum (NAS) Signaling
The Non- Access Stratum (NAS) signaling terminates at the MME and it is also responsible for generation and allocation of temporary identities to UEs.

4. Roaming (S6a to Home HSS)
 It checks the authorization of the UE to camp on the service provider’s Public Land Mobile Network (PLMN) and enforces UE roaming restrictions.

5. NAS Chipering & Integrity Protection
The MME is the termination point in the network for ciphering/integrity protection for NAS signaling and handles the security key management.Lawful interception of signaling is also supported by the MME.

6. Inter MME and IRAT mobility
The MME also provides the control plane function for mobility between LTE and 2G/3G access networks with the S3 interface terminating at the MME from the SGSN.

7. Idle Mode tracking

8. Paging


MME hardware solution can be re-utilised the existing SGSN network element, most all vendors already have SGSN extended capability to be MME function.