What does device type mme mean?

MME (Mobility Management Entity) is the key control node of the 3GPP protocol LTE access network. It is responsible for the positioning of UE (User Equipment) in idle mode, the paging process, including relay. Simply put, MME is Responsible for signaling processing part.

It involves the bearer activation/deactivation process and selecting an SGW (Serving GateWay) for a UE when it initializes and connects to the UE. Authenticate a user by interacting with HSS and assign a temporary ID to the user. MME also supports interception and monitoring within the scope permitted by law. MME provides a control function interface for 2G/3G access networks through the S3 interface. For roaming UEs, the S6a interface is also provided for HSS.

Functions of MME:

1. Access control, including security and permission control.

2. Mobility Management

Mobile networks must clearly know the current location information of users, and EPC networks are no exception. The location area in the EPC network is called TA (Tracking Area), which is similar to the location area LA (Location Area) managed by MSCS and the routing area RA (Routing Area) managed by SGSN, and is used for user mobility management of the EPC system. According to different scenarios, it can be divided into: location updates between different eNodeBs in the same MME, location updates between different MMEs, periodic location updates, etc. The result of all successful location updates is that the terminal notifies the TA of the current location area where it is located. to the network and recorded in the MME and HSS network elements.

3. Attachment and detachment

The terminal must complete the registration process in the network before performing actual services. This process is called attachment. The terminal that is successfully attached will obtain the IP address assigned by the network and provide a "permanently online" IP connection; different from the traditional 2/3G network, the EPS network directly establishes a default bearer for the user through initial attachment, while the 2/3G network The user needs to activate the PDP context after attaching before the IP address is assigned to it.

When the terminal does not need or cannot continue to attach to the network, it will initiate a detachment process. Depending on the initiator, detachment can be initiated by the UE, MME or HSS. The detachment initiated by the MME may be due to The terminal has not interacted with the network for a long time, and the detachment initiated by HSS is due to the user's contract, billing information, etc. The network actively disconnects from the terminal; depending on whether the terminal is successfully notified, it is divided into display and privacy detachment. , the former refers to the situation where each other uses signaling to notify each other, and the latter refers to the situation where the network side actively initiates but cannot notify the terminal due to wireless conditions.

4. Session management function

Including the establishment, modification and release of EPC bearers; when interacting with 2G/3G networks, complete effective mapping between EPC bearers and PDP contexts; Establishment and release of bearers on the access network side; selection of appropriate routes based on APN and user subscription data

5. SGW and PGW selection

When users have data service requests, MME needs to Select an SGW/PGW to forward user data packets.

Generally speaking, MME is similar to the control plane function of the SGSN network element. The separation of the control plane and user plane functions of the network element is more conducive to the deployment of flat network. In addition to the above mobility management functions, MME is also responsible for the management of legal interception, user roaming control, and security authentication.