Beam switching without tci present in DCI IE and group based beam reporting disabled?

5G NR
1

Hi 5G Experts,
For csi-report config I’ve seen most of times report quantity = cri-ri-pmi-cqi.
Please check for below understanding cri ie CSI reference signal resource indicator indicates position of CSI -RS which UE measures as per nzp csi-rs for channel measurements so UE can report cqi, ri, pmi.
Position of csi-Rs depend on type of row defined in nzp csi-rs resource structure.
Same logs its observed tci present in dci within pdcch config setup not present, so how UE will do now beam switching.
As per my understanding for beam switching report quantity to be cri rsrp or ssb index rsrp so ue can report L1 rsrp, but in logs only single csi report config to add mod list there with report quantity cri-ri-pmi-cqi.
Group based beam reporting is disabled.

2

CSI-RS Periodicity can be calulated as:
Function (numDSlotsInRF, numCSI-RS Including TRS, numSSBInSSBPeriodicity, numSwitchsPerSlot)
numDSlotsRqd = W/2+W/2+(N*W)
CSI_RS_period = CEIL(numDSlotsRqd /numDlSlotsInRF)
CSI_RS_period = MAX(SSB_periodicity, CSI_RS_period) In RFs.
CSI_RS_period = CSI_RS_period/ SSB_periodicity + (=CSI_RS_period/ SSB_periodicity )?CSI_RS_period/%
SSB_periodicity:0;
a)Schedule 2 SSB’s per slot
b)Schedule 2 TRS per slot(D slot other than SSB slot)
c)Wideband CSI-RS would fall in last symbol of the slot in SSB/TRS slot. Half of CSI-RS are in SSB slot beam and Half of CSI-RS are in TRS slot beam.
d) Schedule wideband CSI-RS overlapped with corresponding SSB symbol but non overlapping RB if possible.
e) Schedule each narrow beam CSI-RS in D slots(other than b) and c) ). One CSI-RS per D Slotf)
When CSI-RS and PDSCH DMRS overlaps in symbol, avoid DMRS CDM groups on CSI-RS RE’s.
CSI-RS and SLIV Option 1: always exclude last symbol (CSI-RS symbol) in CSI-RS slot. SLIV=1-12 or 2-12

3

Thanks a lot @Shantnu_Singh!!
But my query is for basically beam switching without tci present in DCI IE and group based beam reporting disabled.
Is it possible still for UE to switch beam?

I’m checking in parallel logs if its for 5G on FDD, then it can be possible as its having single ssb with no csi-rs beam.

4

You are using codebook type 1 or type 2.
As far as I know, codebook type 1 is not beamformed (it’s only broad beam or it’s just a type of common channel beam).
So here beam sweeping will not apply.
Please correct me if I am wrong.

5

In nzp csi resource we can check for this option, i.e. row configured.

6

It’s codebook type 1 but codebook type 1 again of two types single panel or multi panel which used for SU MIMO, so it can be beamformed.
Codebook type 2 used for MU MIMO.
Please correct if its wrong.

7

Yes, it’s for MU MIMO.
And you are right can be beamformed but in our Ericsson still its not implemented atleast not in our network.

8

Ok, thanks for info. It seems in your case single ssb.

9

Yes, correct.

10

If ssb greater then 1 then only beamforming works.
It’s key point.

11

So for single ssb we should not see multiple beam indexes if drive testing is done.

12

I think: By using the combination of N1N2 O1 O2 beam sweeping can be done in a smaller step.
Here if you check the functionality of O1 and O2 is to determine the sweeping in horizontal and vertical direction.
Please to correct me if am wrong.
And this applies for Codebook type I, right?