Sign in Subscribe

MME Mobility Management Element

Last updated on 

MME stands for Mobility Management Element, which is a component of the Long-Term Evolution (LTE) system architecture. The MME is responsible for managing mobility-related functions for LTE networks, including tracking user locations and managing handovers between different cells. In this article, we'll dive deep into the workings of the MME and explore its functions and capabilities.

Introduction to LTE Networks

LTE is a wireless communication standard that offers high-speed data transfer rates and low latency for mobile devices. The LTE network architecture comprises several functional elements that work together to provide seamless connectivity to users. The main components of an LTE network are:

  1. User Equipment (UE): This refers to the mobile device used by the end user to access the LTE network.
  2. Evolved Node B (eNodeB): This is the base station that connects the UE to the core network.
  3. Mobility Management Entity (MME): This is responsible for managing the mobility-related functions of the LTE network.
  4. Serving Gateway (SGW): This is the gateway that connects the eNodeB to the core network.
  5. Packet Data Network Gateway (PGW): This is the gateway that connects the LTE network to external networks such as the internet.

Functions of the MME

The MME is responsible for performing the following mobility-related functions in an LTE network:

  1. Authentication and Security: The MME authenticates the UE and establishes secure communication between the UE and the core network.
  2. Mobility Management: The MME tracks the location of the UE and manages the UE's handover between different cells as it moves through the network.
  3. Session Management: The MME establishes and manages the UE's session with the core network.
  4. Paging: The MME sends paging messages to the UE to initiate incoming calls or messages.
  5. Lawful Interception: The MME enables lawful interception of communication between the UE and the network for security and surveillance purposes.

Authentication and Security

The MME is responsible for authenticating the UE and establishing secure communication between the UE and the core network. When a UE attempts to connect to the LTE network, it sends a request to the eNodeB. The eNodeB forwards the request to the MME, which performs authentication and security checks before allowing the UE to access the network.

The authentication process involves verifying the UE's identity using a SIM card or a Universal Subscriber Identity Module (USIM). The MME uses the Authentication and Key Agreement (AKA) protocol to authenticate the UE. Once the authentication is successful, the MME establishes secure communication between the UE and the core network using the security keys generated during the authentication process.

Mobility Management

The MME tracks the location of the UE and manages the UE's handover between different cells as it moves through the network. When a UE moves from one cell to another, the eNodeB sends a handover request to the MME. The MME decides whether to allow the handover and selects the target eNodeB for the handover.

The MME maintains a database of UE location information called the Tracking Area List (TAL). The TAL contains a list of Tracking Areas (TAs) that the UE can access. A TA is a group of cells that the UE can move between without triggering a location update. When the UE moves out of a TA, it sends a location update to the MME to update its location information in the TAL.

Session Management

The MME establishes and manages the UE's session with the core network. A session refers to the communication between the UE and the core network for a specific service, such as internet access or voice calls. The MME creates and manages session-related information such as Quality of Service (QoS) parameters and billing information.

ME also coordinates with the SGW to establish and maintain data bearer channels for data transmission between the UE and external networks. The MME uses the Session Management Function (SMF) to manage the UE's session with the core network.

Paging

The MME sends paging messages to the UE to initiate incoming calls or messages. When a UE is in idle mode, it does not establish a connection with the network, and the network cannot send any messages or calls to the UE. To initiate an incoming call or message, the MME sends a paging message to the UE, which triggers the UE to establish a connection with the network.

The MME uses the Paging Control Function (PCF) to send paging messages to the UE. The PCF sends the paging message to the eNodeB, which broadcasts the message to all cells in the UE's TAL. When the UE receives the paging message, it responds by establishing a connection with the network.

Lawful Interception

The MME enables lawful interception of communication between the UE and the network for security and surveillance purposes. Lawful interception is a legal process that allows law enforcement agencies to intercept and monitor communication between individuals for security purposes.

The MME provides a Lawful Interception Function (LIF) that enables law enforcement agencies to monitor communication between the UE and the network. The LIF intercepts the communication and sends it to the Law Enforcement Monitoring Facility (LEMF) for analysis.

Conclusion

The MME is a critical component of the LTE network architecture, responsible for managing the mobility-related functions of the network. The MME performs functions such as authentication and security, mobility management, session management, paging, and lawful interception.

The MME uses various functions such as AKA, TAL, SMF, PCF, and LIF to perform its tasks. These functions enable the MME to provide seamless connectivity to users and ensure the security and privacy of communication between the UE and the network.

As LTE networks continue to evolve, the MME is expected to play an increasingly critical role in managing the mobility-related functions of the network. As such, it is essential to have a solid understanding of the MME's functions and capabilities to develop and manage LTE networks effectively.