When NR mode is set to SA + NSA, how device prioritize either SA or NSA?

Hello Experts.

When NR mode is set to SA + NSA, how device prioritize either SA or NSA?

Admin note: this post was updated with image below.
NSA, SA or NSA+SA, 3 modes can be set 1

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In Huawei this is configured in gNB based on SRS SINR to move between SA or NSA.

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I am referring during initial attach / registration.

Seems weird changing SA to NSA via SRS to me though… as same cell is used as hybrid to support for both SA and NSA.

Anybody working with SA commercial network?

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It seems like UE is switching from SA to 4G and vice versa.

I think you should review your idle / connected modes HO / Redirection & cell re-election thresholds from 4G-SA /SA-4G.

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But I’m not talking about 4G.

n1 mode can be set from phone either SA, NSA or SA+NSA.

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You mentioned switching from SA to NSA.

So 5G SA UE doesn’t enter NSA directly.

It will go back to 4G layer and then camp to NSA based on B1 trreshold.

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Nope, some UEs go directly NSA.
While others go to SA.
When set to n1mode to SA+NSA.

Don’t know if you catch my point mate:

  • 5G coverage is -60

  • Same cell supports both NSA or SA.

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Better check your 4G to SA idle mode re selection and fast return thresholds.

These are 2 different points: SA to NSA will always follow 4G route while 4G can directly camp to SA based on your idle/connected mode thds, including fast return

So again, as per your initial query, if you switch from NSA to SA and vice versa, this definitely involves 4G

Also is this CS service or PS service?

Or idle.

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It is PS.

We don’t switch UE either camp on NSA or SA initially.

And I think it is be related with n1mode setting at UE.

So it is not about mobility, nor voice fallback.

To reselect SA from LTE sib24 is needed.
It is not enabled right now.

So, need advices on n1 mode in device side.
NSA, SA or NSA+SA, 3 modes can be set.

NSA, SA or NSA+SA, 3 modes can be set 1

NSA, SA or NSA+SA, 3 modes can be set 2

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Yes we can have same cell support for NSA or SA mode by using deployment mode parameter.

Most of UE support NSA+SA and in 5G auto mode setting.

UE will try first to register with SA cell by RACH procedure.

And if it’s fine then PS call work over SA cell.

Otherwise UE will enter into NSA mode for same cell by X2 setup between 4G and 5G cell and then SCG addition.

So in summary: Device always try for SA first. If it gets failed to latch on SA cell due to RACH issue, RRC reject etc. then device try for NSA mode. Same cell can be SA or NSA in network as per deployment mode parameter set.

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That’s what I assume as well bor, but not all devices look for SA first.

So I assume it is a firmware issue. (?)

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