Question

On what basis we can decide tracking area with respect to cell/eNB or something else?

i.e. 1 Tracking area belongs to 1 cell /eNB or etc.

Answer 1

On behalf of Bart:
This is someone's full time well paid job.

The idea behind it is to create TAs in a way areas will be small yet still meaningful. Plus amount of signaling optimal. For example if the TAs will be big by covered area you will have small number of TAUs, but in the same time shitload of Paging Req to all eNB in this TA.

I'm not radio eng but I believe this is just one of the problems as you have to remember you also have infrastructure between eNBs and MME which in most cases is rather spread as radio towers are spread.

Answer 2

Multiple eNB/cell can be in one Tracking area. Tracking area is defined at core n/w. When UE is in idle mode then UE can move to any cell those cells belong to same Tracking area without doing any tracking area update.

Answer 3

Remember that a TA consists of a cluster of eNodeB's, it means that every cell of an eNodeB has the same TAC.

Now, the size of the TA could be flexible, but take in count that a small TA has too much TA updates, and a big TA has a lot of paging load.

For decide the dimmensioning of your TA you have to take in count the capacity of EnodeB and MME, also take in count how much paging are you going to handle.

The TA is a label used to separate clusters.