How RU cater for 16 layers with less then 16 ports?

I think transmission scheme 1 is not related to UE its for gNB transmission on PDSCH.

image

Huawei support 16 layers with 64T6R and 32T32R.
How is this possible with transmission scheme 1?
Or am I missing something…

It’s mentioned “the UE may assume” so it is for one UE max 8 layers.
As of today DL mimo is limited to 4 layers anyway.

Yes and that is with single CW.

MIMO Transmission Scheme 1: Closed-loop transmission where data and DM-RS are transmitted with the same precoding matrix.
Demodulation of data at the UE does not require knowledge of the precoding matrix used at the transmitter.
Note: spatial multiplexing and rank-1 are included.

Yes, 2 codewords are needed only for rank 5,6,7 or 8.

Do you mean transmission scheme 1 is for UE and if 4 layer with 1 CW is currently supported right thn for example we have 8 SSB and with polarization there will be 16 layers, correct?

8 ssbs are to cover the whole sectors.
Why do you consiser that 8 SSB will be transmitted in the same time?
Where are csi-rs beams in your explanation?

Yes its in sweeping mode only but can be allocated for different users SSB per tti scheduling i havent consider beam refinement now
I want to understand pdsch 16 layers and transmission scheme 1 relation …
2 SSB can have 4 layers +45 / -45 now what is role of transmission scheme 1.
If I am using 4 layer then only 1 UE with 4x4 mimo possible.
So, transmission scheme 1 limiting number of layer to 8 does it means that > 2 UE can not be possible with 4x4 MIMO?

Each SSB covers a specific area of a cell.
How do you expect 2 SSB to cover same UE?

Not same ue but for 4x4 MIMO we need 2 beams, right?
So 2 SSB is anyways are required to perform 4x4 MIMO.

Each SSB covers a diferent area.
They do overlap just enough to ensure coverage continuity but in general each SSB has its own area of coverage.
You cannot expect an UE to be served by 2 or 4 SSB.

I am not saying its served UE with 2 SSB.
I understand each SSB cover different area but for 4x4 MIMO we need 2 SSB, correct?
Not considering beam refinement.

Layers are mapped to csi-rs ports using precoding matrix.
Then signal is beamformed in the air so at the receiver it reaches with a high gain (summing with max from each tx csi-rs port for different rx antenna of the UE).
There is always one ssb beam that covers one UE to my understanding.

Please red paragraph “putting all those together” from sharetechnote:

https://www.sharetechnote.com/html/5G/5G_CSI_RS_Codebook.html

I am also having same understanding as explained by @RFSpecialist.
One more thing to add SSB beams are based on coverage scenarios in Huawei. Like SSB beam 8, 6, 4…

image

As of now, I have tested with DL MU-MIMO 8 layers and UL 4 Layers.

Secondly, MU-MIMO was used with 100 SRS BF weight and later we tried 100 PMI based (CSI-RS periodic only). It means for MU-MIMO we are not having any bottleneck for CSI -RS port limit as we don’t use PMI for BF weight. On cell edge if SRS is not reliable then only we can have CSI-RS & PMI based BF weight.

Same like in LTE TM7 is not having any CSI-RS and all BF is based on SRS. Still we can achieve 16 Layers under DL MU-MIMO… CSI-RS is maintly used for SU-MIMO and its next to impossible to have higher than 4 layers… event Rank 4% is almost zero in all networks.

In Huawei there is a parameter whether weights are based on srs or csi-rs measurements.
When UE is in good SINR srs weights are used, when in poor sinr then csi-rs pmi are used.
There’s also an hysteresis of around 6 dB in sinr between those 2 to avoid ping-pong.

I honestly think Huawei is very much advanced in 5g compared to other vendors.
They use to have release 1.9 2.0 2.1 3.0 3.1 and now release 5.0 for 5G.
They have so many features that is very easy to get lost among them.

Hi @ajaymsfather, thanks for the information.
Understanding it is correct I am also saying number SSB depends on the coverage scenario based on azimuth and elevation.
Another is CSI RS port is not related to the number of layers.
My query is what is the relation of transmission scheme 1 and the number of PDSCH layers?
As in LTE, we have different TM with 16 layers.
Secondly without 2 SSB how 4*4 MIMO possible for UE?

4x4 MIMO we need 2 SSB with cross polarization

Very true. Its well advanced and specially for Mu-MIMO as there is no 3GPP standards so its horse race to get max thrput among vendors.

This picture does mention beams but it does not mention SSB beams.

Yes but without beam refinement its SSB only right.
Otherwise it can be CSI or SSB.
Whether it is SSB or CSI RS; 4x4 MIMO we need 2 beams this is my understanding as of now.

When it’s about +45 and -45 degree polarization I think you mix layers with csi-rs ports.
Only csi-rs ports can be with polarization; mimo layers have nothing to do with polarization please read again sharetechnote paragraph that I mentioned above.