How SSB config is done during CA addition?

5G NR
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1

Hello NR Experts.

I have query regarding CA addition in SA network.

Let’s say UE add CA for n78_n41
n78 is pcell and n41 scell

UE latched to n78 with 2 SSB beams and n41 with single SSB.

Then during CA addition with n41 how SSB config done?

Will UE drop SSB for n78?

2

At a time, UE can be served with only one SSB beam.

3

Thanks!

At CA addition you mean all bands with single SSB only works?

Like CA-n78-n41
n78 pcell with single SSB + n41 with single SSB?

4

Even without CA it would be single SSB for CA.

5

If UE is 4 RX, then 2 SSB can be used at a time.

Why you mentioned single SSB always?

6

What do you mean by 2 SSB?

Are you referring to 2 PSDCH beam?

At a time only one SSB beam will be serving beam.

Please let me know if any misunderstanding…

7

Actually its seen with 2 SSB data flow there on 4 layers.

8

PDSCH layer are different thing and SSB serving beam is different.

9

I think it’s vendor specific like Huawei having different

For Nokia it’s same only.

10

But serving SSB beam would be only one at a time irrespective of vendor.

11

It depends on vendor.

Nokia old time was able to deliver only via SSB beams.

But now I think they have PDSCH beams as well.

Same Like Huawei.

Huawei also have PDSCH beams.

12

Question is not about PDSCH beam but pure SSB beam. Can UE be served by 2 different SSB beams at one time?

SSB beam, which UE monitor for mobility.

13

For mobility UE monitor multiple beams and which all beams need to monitor, n/w convey this info to UE.

14

I mean how many are serving beams?

15

Serving beam is 1 only as per my understanding.

16

Mine too: there can be only one.

Besides SSB beams have different locations in space.

So there will always be only one dominant, unless UE stops somewhere in-between them to have same RSRP from different SSB beams.

17

A UE can measure and report multiple SS PBCH Blocks simultaneously.

It depends on configuraiton of the parameter groupBasedBeamReporting as per 38.214.

I didn’t fully follow the conversation, but if this is what you are looking for…

18

Exactly this was only my point!

19

I think Ericsson has just one SSB for entire cell.

20

Yes, that’s true.