In LTE paging area is called as TAL (Tracking Area List). MME pages the entire TAL for delivering page to a UE. A TAL can have maximum 16 TA (Tracking Areas). When a UE moves from one TA to another within the same TAL it does not require to do TA update.
If TA is too big the paging load will be high, while if TA is too small TAU load will be high. In order to plan the size of Tracking Area we need to strike out a balance between the paging load and TAU (Tracking Area Update) load.
Below are the basic principles of TA planning:
1. When the suburban and urban area are covered discontinuously, an independent TA should be planned for both the areas.
2. Configure different TAL for geographically discontinuous areas
3. In a TAL all the TAs should be near one another
4. The paging area (TAL) can not span across different MME
5. If there are mountains or rivers in the area under planning, the same can be used to plan TAL boundary
6. The size of TAL can use existing 2G/3G LAC as reference. This is important for CSFB (Circuit Switched Fall Back) planning. If TAL is mapped to LA, there is no need to do LAU (Location Area Update) when UE does CSFB. This will reduce CSFB call setup duration
