What is TAI (_List) Tracking area identifier (_List)

Within the mobile communication landscape, particularly LTE (Long-Term Evolution) and 5G networks, the Tracking Area Identifier List (TAI List) serves as a fundamental mechanism for managing user equipment (UE) mobility and optimizing network efficiency.

Understanding the Need for TAI Lists:

• Cellular networks are divided into smaller geographical regions called Tracking Areas (TAs). Each TA is identified by a unique Tracking Area Identifier (TAI).
• As UEs move around the network, they transition between different TAs. Frequent updates to the network core about every TA change would be resource-intensive for both the network and the UE's battery life.

The Role of TAI Lists:

• The TAI List acts as a pre-approved list of TAs that a specific UE is allowed to access. This list is stored both on the UE and within the network core (specifically, the Mobility Management Entity or MME).

Components of a TAI List:

• Each entry in the TAI List consists of a TAI itself. The TAI is a three-part identifier:
  • Mobile Country Code (MCC): A unique identifier for the country where the network operates.
  • Mobile Network Code (MNC): A unique identifier for the specific mobile network operator.
  • Tracking Area Code (TAC): A code assigned to a specific TA within the network.

Maintaining the TAI List:

• The network core (MME) is responsible for generating and updating the TAI List for each UE.
• Factors influencing the TAI List creation include:
  • UE subscription information: The network might consider the user's typical roaming area or service plan when generating the initial TAI List.
  • Network configuration: The network might restrict access to certain TAs based on factors like network load or security considerations.
  • UE location updates: As the UE moves and performs initial registration or handover procedures, the network can update the TAI List to reflect the new location and potentially add neighboring TAs for seamless roaming.

Benefits of TAI Lists:

• Reduced Signaling Overhead: By eliminating the need for constant updates about every TA change, TAI Lists significantly reduce signaling traffic on the network, improving overall network efficiency.
• Battery Conservation: UEs don't need to send frequent location updates as long as they stay within the TAs included in their TAI List, resulting in extended battery life for mobile devices.
• Optimized Handovers: When a UE moves from one TA to another within its TAI List, the handover process is simplified as the network is already aware of the allowed TAs.

Additional Considerations:

• In some network architectures, UEs might be assigned a default TAI List containing all TAs within the network operator's coverage area. However, more granular control is often implemented through customized TAI Lists.
• The network can dynamically update the TAI List over time based on the UE's location and network conditions.

LTE and 5G Considerations:

• The concept of TAI Lists remains relevant in both LTE and 5G networks.
• 5G networks might introduce additional functionalities related to UE positioning and network slicing, potentially influencing how TAI Lists are managed in the future.

Conclusion:

The Tracking Area Identifier List (TAI List) plays a critical role in mobile network management by facilitating efficient UE mobility and optimizing network resources. By providing UEs with pre-approved access to specific TAs, TAI Lists reduce signaling overhead, conserve battery life, and streamline handover procedures, ultimately contributing to a seamless and efficient user experience.