What is a Tracking Area in LTE?
Let me explain what a tracking area (TA) is in LTE, and why it’s essential for network operation. A Tracking Area is a designated geographical region within a mobile network where user equipment (UE), such as smartphones or tablets, can be tracked for location-based services.
The concept of the tracking area plays a vital role in the efficient operation of the network. It allows for optimized paging, reduces signaling overhead, and ensures that mobile data traffic is efficiently routed.
In the LTE system, a Tracking Area is defined by a unique identifier known as the Tracking Area Code (TAC). This TAC is used by the network to group specific cell sites together to form a tracking area. The network operator will decide how many cells to group in one tracking area, depending on factors like network topology and traffic demand.
How Does Tracking Area Work?
As you move around within the LTE network, your phone or device communicates with the eNodeB (Evolved Node B), the LTE base station. Your device will register with the network, and the network keeps track of your location within a specific tracking area.
When your phone switches between different tracking areas, it will inform the network, ensuring the system knows where your device is at any given time. This is especially useful for handling things like paging (for calls or messages) when you’re in a different area or roaming.
Why is it Important?
Tracking areas provide a couple of significant benefits:
- Paging Efficiency: When a call or message is incoming, the network sends a paging request to the relevant tracking area instead of broadcasting to every cell in the network. This helps reduce unnecessary signaling overhead.
- Location Management: By grouping cells into tracking areas, the network can efficiently track users’ movements across the network. This is important for mobility management, ensuring that as you travel from one area to another, your device remains connected without service disruption.
- Optimizing Radio Resources: The network can allocate resources more efficiently because it knows the location of each device within the tracking area, making sure the radio spectrum is used more effectively.
What Happens During a Tracking Area Update (TAU)?
A Tracking Area Update (TAU) is triggered when your device enters a new tracking area. The update allows the network to keep your location information current, ensuring that you can receive calls and messages no matter where you go within the LTE network. During a TAU, the UE will inform the MME (Mobility Management Entity) of its new location, and the network will update its records to reflect that.
TAU can be triggered by:
- Moving from one tracking area to another.
- The device’s connection is lost, and the UE needs to re-register with the network.
As we discussed in previous articles, efficient signaling and location management are critical for maintaining seamless connectivity, and TAU is part of that process.