Mobility Management Unit on a LTE network is centralized control unit for key operations on Access Network and Core Network.
Some of the roles of MME are listed below :-
Network access control (NAC)-
NAC is involved in authentication and authorization for the UE (mobile phone). Required for IP connectivity.
Radio Resource Management (RRM) -
RRM is system level control for managing Radio parameters involved in wireless communication between US and base-stations/e-NodeB. The key radio parameters that needs to be managed efficiently are listed below.
1. Dynamic transmit power control.
2. Modulation scheme management and data rates handling.
3. Channel allocation and de-allocation.
4. Handover requirement detection and switching.
5. Error correction schemes.
Mobility Management (Handover)
During hand over a UE is switched from source eNodeB to a target eNodeB. The reason of handover is related to mobility of the UE across the cell boundary. Example is of a UE in a moving vehicle.
This is related to accounting/billing of user on the move across various service providers in different regions.
Load balancing between S-GWs