A quick question: Can a missing TAC/LAC Mapping in Core hinder/stop/delay cell re-selection from 3G to 4G?
Or it can just delay the CSFB Process only?
Note: 3G to 4G Cell Reselection Parameters and Features are correct and aligned.
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Core configurations will only affect CSFB.
We don’t have TAC to 2G LAC and reselection (2G to 4G) works fine.
What affects reselection with (vendor Huawei) are so many things.
From external cells to the dummy external relations done on RNC level.
Also wrong TAC LAC on external cell definitions (not only the neighbours definitions) will affect reselection.
When you say not parameters are correct.
List the MOs that you are considering as correct if vendor is Huawei.
I think that missing TAC/LAC mapping at MME also delay 3g-4g reselection.
During irat reselection, UE send its old 3G LAC & TMSI. 4G MME will ask UE context from 3G MSC.
If TAC/LAC mapping is correct, mme can chose msc immediately.
If TAC/LAC mapping is missing, mme need query dns about ip address of 3G lac provided by ue, it take longer time.
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MME is not part of any idle mode reselection be it 3G to 4G or 4G to 3G,
My suggestions are below…
Neighbor definition from 3G to 4G are correctly defined. Especially for overlapping or adjacent LTE cells.
source UMTS to target LTE EARFCN properly defined.
SIB configuration and modification update period are set to recommend values
Lastly, LTE reselection target should be set to optimal value along with highest priority.
TA update has no correlation with TAC and LAC mapping, that’s obviously has to be done after reselection to LTE. (Contrary to my previous point)
Hi Experts, we have some 4G-2G only Colocated sites in the network, what is the strategy for TAC-LAC mapping in this scenario, should we make TAC Island for these 4G (2G Colocated) sites and configure TAC-LAC(2G) mapping on core end or follow the same strategy for TAC-LAC mapping as 4G-3G sites?
Hello All.
In a 4G only network, in Core side, do you need to define TAC LAC relation?
Like create a dummy LAC?
Or it just needs TAC?
It’s required.
If you do combined attach for SGs interface for csfb implementation.