Example of RI/CQI/PMI report from UE in 5G

HI All.
Below is an example of RI/CQI/PMI report from UE in 5G:

It is good to note that UE does not transmit a whole matrix. Only some coefficients like i1,1 i1,2 i1,3 and i2. Then teh GnodeB will constitute the matrix based on csi-rs ports, layers and n1,n2 and o1,o2 as explained on Sharetechnote:


Size of precoding matrix is PxL meaning P=csi-rs ports (lines in PMI matrix) and L= layers (columns in PMI matrix)

@RFSpecialist, based on PMI 1, i1, i2, i3 GNB constiture layers (PDSCH) and N1, N2, O1 & O2 are fixed per CSI RS port & antenna pannel configuration so for example if we have 2 x 2 x 4 x 4 = 64 beams .
Which are those 4 beam will be selected for PDSCH layers (8 layers) out of 64 beams?
In another way are these 64 beams are transmitting and among these beams UE will report 4 beams PMI?

User data = # of layers are mapped with CSI RS signal thn precoder and radio transmission.

Query is user data (PDSCH) are transmitting on which beam if we say PDSCH beam thn is it CSI RS beam which we are talking about (1SSB = 4 CSI RS) or is it different GoB?

In this picture r0 r1 are dmrs not csi-rs.
Use case 4 from same page.

Ok thanks it is DMRS but query is PDSCH is trasmitted on which beam?
For 1000 - 1011 PDSCH beam use to tramsmitt PDSCH with upto 8 layers as per TS1.
On which beam PDSCH transmission happen?
And PMI sent by UE 1, i1, i2 and i3 represent 4 beam of CSI RS out of # beam defined as per CSI RS port?

Pdsch are transmitted on one or several beams of sector beams (GoB).

GoB comprise of SSB beam or CSI RS beam, right?

In Huawei ssb beams are static (predefined static weights) and pdsch are dynamic beams.
Csi-rs beams are not always enabled.
All that gNodeB need to know is the PMI report to constitute weights for csi-rs ports.

PDSCH beams are separate in Huawei from CSI RS and SSB?
Because I haven’t heard this word PDSCH beam in Nokia.

If you can share some more details about PDSCH beam and the relation between CSI RS beam & SSB beam that will be useful.

Need to understand how csi-rs beam and ssb beam in mmWave.
Now question is this one: when gNodeB use UE PMI reports to generate beam weights and when gNodeB uses csi-rs beams reports ( 4 strongest beams) to generate beam weights?

For Samsung system, PDSCH beam mostly same as CSI-RS beam.

Yes, that is what my understanding is.

Does this mean that csi-rs beams are always enabled? UE must be informed in which frame/slot/symbol and frequency is transmitted each csi-rs beam.
Do you see this in logs (RRC reconfig)?

gNB use weight to generate PDSCH beam or it refined CSI RS beam based on PMI.


Here is disconnect. CSI-RS beams not enabled always.
So without CSI-RS beams… pdsch beam = ssb beam only.

However, PMI also plays role in deciding which CSI-RS beam to put weighting on.

This is also my understanding that csi-rs beams are not always enabled.

When I worked on NR parameter for CSI-RS beams set false, so as per my understanding then data flow on ssb beam only.

Can anyone paste this information from a UE Log?
Unless we see this we cannot conclude that csi-rs beams are enabled… :slight_smile:

Just remember that each csi-rs beam points into a different direction/angle in space and it has different weights.

How many of this you see?

And where is the frame/subframe and slot when is transmitted each of the 64 csi-rs beams?