Hi Experts,
Question: how csi-rs reference signals in 5G reach the UE since are transmitted from one logical antenna?
If transmitted from one logical antenna will have not enough gain to reach the UE.
One logical antenna port does not provide enough gain.
See snap from ShareTechNote:
Is number of physical antenna mapped to a logic antenna dynamic?
Yes, also csi-rs ports number is parameter.
Group of antenna element design antenna port and that is logical group array.
What is the meaning of single logical antenna transmission?
Can you explain it in more detail?
For UE antenna port is transparent and would expect reception in 1 logical antenna with each transmission scheme.
Ue expects one transmission for each csi-rs port.
So if csi-rs ports are 8 there will be 8 data streams sent to UE.
Don’t confuse MIMO layers with csi-rs data streams.
Correct that is transmission scheme 1.
Ok 1 ssb have 4 refined beam?
Each refined beam have csi rs signal.
Correct if I am wrong.
8 layers of mimo need 8 csi rs or not?
No, mimo layers is independent from csi-rs ports.
You can have 2 mimo layers with 8 csi-rs ports.
Yes, mostly this is the case.
Or you can have 3 mimo layers (PDSCH layers) with 16 csi-rs ports.
To my understanding, each csi-rs port will have its own reference signal.
How 2 mimo layers means 2 PDSCH layers need 2 csi rs signal and 2 csi rs resources mapped with 8 port csi rs.
Is it?
We should not confuse csi-rs ports, csi-rs reference signals and csi-rs beams.
4 csi rs beams required for it if refined beam enabled otherwise 4 ssb beam needed.
That is ok for 4 layers if it is corse beam or refined beam.
1 csi rs port can generate 8 csi rs signal?
To my understanding each csi-rs port will have its own reference signal.
Ok now 8 layers need 8 csi rs signal?
1 ssb beam or CSI-RS beam = 2 layers.
Please correct.
1 SSB beam has usually 4 csi-rs beams.
Yes exactly if refined beam enabled.
We need to quantity layers in term of ssb or CSI-RS beams I mean.
1 ssb or CSI-RS beam = 2 layers.
Yes, each beam (no matter if large or narrow, SSB or CSI_RS beam) has 2 layers: + 45 and - 45.
For csi-rs signal my understanding is that its per layer UE need to measure.
How many csi rs port required to generate 2 cross polirize csi rs beam?
It could be more than 2, right?
csi-rs port is parameter even for Ericsson or Huawei.
Could be 8, 16,12 depending on AAU.
