GUMMEI (globally unique MME identifier)

Last updated on Apr 12, 2023

The Globally Unique MME Identifier (GUMMEI) is an essential element in the Long-Term Evolution (LTE) network, which is a standard for wireless communication. GUMMEI is used to uniquely identify the Mobility Management Entity (MME) of a user equipment (UE) when it moves from one tracking area to another. In this article, we will discuss in detail what GUMMEI is, its importance, how it works, and its benefits.

What is GUMMEI?

GUMMEI stands for Globally Unique MME Identifier. It is a unique identifier that is assigned to an MME in an LTE network. MME is responsible for managing the signaling between the UE and the core network. When a UE moves from one tracking area to another, it sends a tracking area update request to the MME. The MME, in turn, forwards the request to the core network. The core network then sends a location update message to the HLR/HSS (Home Location Register/Home Subscriber Server) to update the UE's location.

The GUMMEI is a 64-bit identifier that consists of two parts:

MME Group ID (MMEGI): It is a 16-bit identifier that identifies a group of MMEs in a pool. The MMEGI is assigned by the network operator.
MME Code (MMEC): It is a 8-bit identifier that identifies a specific MME in a group. The MMEC is also assigned by the network operator.

Together, the MMEGI and MMEC uniquely identify an MME in the LTE network. The GUMMEI is stored in the UE's SIM card and is used to identify the MME when the UE moves from one tracking area to another.

Why is GUMMEI important?

The GUMMEI is important because it enables the core network to identify the MME that the UE is attached to. This is essential for several reasons:

Handover: When a UE moves from one tracking area to another, it may need to handover to a different cell. Handover requires the core network to know which MME the UE is attached to so that it can initiate the handover process.
Paging: When the core network needs to establish a connection with the UE, it sends a paging message to the MME. The MME then sends the paging message to the UE. Without the GUMMEI, the core network would not know which MME to send the paging message to.
Charging: The GUMMEI is also used for charging purposes. The network operator can use the GUMMEI to identify the MME that the UE was attached to when it made a call or used data. This information is used to calculate the charges for the call or data usage.

How does GUMMEI work?

When a UE moves from one tracking area to another, it sends a tracking area update request to the MME. The tracking area update request includes the UE's current location and the GUMMEI of the MME that the UE is currently attached to. The MME then forwards the tracking area update request to the core network.

The core network uses the GUMMEI to identify the MME that the UE is attached to. It then updates the UE's location in the HLR/HSS. The core network also sends a location update message to the MME to inform it that the UE has moved to a new tracking area. The MME then sends a tracking area update accept message to the UE, which includes the GUMMEI of the new MME that the UE is attached to.

If the UE needs to handover to a different cell, the core network uses the GUMMEI to identify the MME that the UE is currently attached to. It then initiates the handover process with the target cell. The target cell sends a handover request to the target MME, which includes the GUMMEI of the source MME. The target MME then forwards the handover request to the source MME. The source MME then initiates the handover procedure with the source cell and sends a handover command to the UE, which includes the GUMMEI of the target MME. The UE then switches to the target cell and sends a handover complete message to the target MME, which includes the GUMMEI of the source MME. The target MME then forwards the handover complete message to the core network.

If the core network needs to establish a connection with the UE, it sends a paging message to the MME that the UE is attached to. The MME then sends the paging message to the UE. If the UE does not respond to the paging message, the MME sends a paging request to the neighboring cells. The neighboring cells then send a paging message to the UE. When the UE responds to the paging message, it sends a location update request to the MME that the paging message came from. The location update request includes the UE's current location and the GUMMEI of the MME that the UE is currently attached to.

Benefits of GUMMEI

The use of GUMMEI provides several benefits to the LTE network:

Efficient handover: GUMMEI enables efficient handover between cells. The core network can quickly identify the MME that the UE is attached to and initiate the handover process.
Better network management: GUMMEI enables better network management by allowing the network operator to track the location of UEs in real-time.
Enhanced security: GUMMEI provides enhanced security by ensuring that the UE is always attached to the correct MME. This helps prevent unauthorized access to the network.
Improved charging: GUMMEI enables improved charging by providing accurate information on the MME that the UE was attached to when it made a call or used data. This enables the network operator to calculate charges more accurately.

Conclusion

In conclusion, the Globally Unique MME Identifier (GUMMEI) is a unique identifier that is assigned to an MME in an LTE network. It enables the core network to identify the MME that a UE is attached to when it moves from one tracking area to another. GUMMEI is important for several reasons, including efficient handover, better network management, enhanced security, and improved charging. The use of GUMMEI provides several benefits to the LTE network, including improved efficiency, better security, and enhanced charging accuracy.