Hi there is one mapping table for csi-rs antenna ports with N1,N2 and O1,O2
What are these N1, N2 and O1, O2?
At max we can go as of now in DL for 44 or 42
So, can I assume at max we can use 4 CSI-RS ports?
I guess N1 N2 are cross polarized antenna element count.
Don’t know about O1, O2.
What value for MIMO mode configured in other vendors?
Is anyone using 8x2 or 8x4 for NR?
For FR1 considering 64T64R antenna.
N1, N2, O1, O2 are the number of distinct beam locations on the ground of the steered beam.
I find with 64T64R there can be 8 CSI rs port 2 per sub panel.
It’s like 4 sub panel having 16 cross polarized AE.
So at max we can go upto 8 beams using antenna.
But as of now only 2 ssb beams considering 4x4 mimo for FR1.
N1xN2x2 is the number of csi-rs ports.
Just thinking with 64 + 45 and 64 - 45 how many beams can be generated for NR FR1 is it fixed to 8.
Ssb as per 3gpp or can be more.
Ssb beam 1 = 2 layer.
Ssb beam 2 = 2 layer.
So like this 4x4 can be possible in DL considering penetrations of 4 RX and 4 TX UE.
So with 8 ssb it’s 16 layers max we can go.
Using 64T64R antenna.
Can we say 1 CSI-RS port mapped to ssb beam 1?
So for 8 ssb beam we required 8 CSI-RS ports?
No.
Csi-rs ports its an antenna property.
An antenna can have n1n22 csi rs ports.
The more csi-rs ports the narrower is the beam.
I am assuming there are no refined beams.
So csi-rs used for channel measurement i.e. csi.
You still need csi-rs ports for beamforming even for ssb.
So UE need for each SSB beam reporting of csi by measuring csi -rs so UE beam can be formed by using fixed antenna weights.
Ssb are beamformed.
In that way I’m assuming 8 CSI-RS ports mapped with 8 ssb beams.
Whole process like after rach sync over best beam:
- UE will measure CSI-RS to repport csi then gnb allocates mcs, prb i.e. TBS given to UE as per radio conditions.
- Resource allocation 0 or 1 used in DL.
I find now for 2*2 mimo 2 csi-rs ports configured.
For 2x2 mimo antenna port 3000, 3001 port
For 4x4 mimo antenna port 3000, 3001, 3002, 3003
This is not massive MIMO.
Number of csi-rs ports is not related to rank of MIMO.
Yes, I’m talking for SU-MIMO, please check.
Here’s the connection between mimo layers and csi-rs ports regardless if su or mu-mimo
At the bottom of this page: 5G | ShareTechnote
csi-rs ports is constant no matter if 1 layer, 2 layers or 4 layers.
I find above mapping in some document what I mentioned for csi-rs port mapping with ssb beam.