UE not campping on desired TDD Layer

Hello All.

We have a site with LTE FDD & TDD configuration with L-TDD layer prioritized for idle mode/cell reselection.

But UE (supporting TDD-B41) does not camp on the desired TDD layer.

And instead camps on FDD layers.

Any idea if this behaviour of UE is kind of forced by the reselection algorithm within the UE (prefer FDD over TDD)?

Reselection criteria for TDD might not satisifed (ThershXHigh).

Cell selection depends on rx Lev setting.

Means, what is your qrxlev min and as well on DL rssi as well?

May be FDD having more suitable coverage there.

You can try to check priority of TDD cell give it high prio and tune threshx high threshold.
So UE can move from FDD to TDD in idle mode itself.

Should go for MFBI - Multi Frequency Band indicator - Support for Nokia and Huawei.

Priorities, ThreshXHigh, qrxlevmin, all tuned…

Can you please elaborate more on this parameter?

In a scenario where you have B41 supported devices and configured cell is with B38, you may enable “MFBIBandAdjAlgoSwitch” switch to make sure you prioritize secondary Band (B41).

This is only applicable if B41 ARFCN is a subset of your B38 frequency.

This is a widely known issue for TDD B41 supported devices.

NBR relations need to be added as I remember but may refer Hedex for further config additional along with the switch.

Well, I don’t have B38 and only TDD carrier defined is B41.

But anyhow I will try to relate this info for any feature/parameter on Nokia side.

Thanks for the insight. :clap:

Are you sure from Core side IMSIs are provisioned to camp on TDD TACs?

I had the same issue. TDD worked fine for CPEs but no working for handsets.

It was found that handset IMSIs are provisioned for FDD TACs only.