In case of beamforming, how the gNB will know the location of the UE?
Beamforming happens based on SRS quality, but SRS doesn’t contain any information regarding the location of the UE.
So how the gNB will know the the location of the UE to perform beamforming.
The RACH resources used by UE are mapped to SSB time index.
Based on that, network will establish beam correspondence with UE and always make sure to have a beam in that direction for that UE.
There are 4 SRS transmitted in uplink and measured by 8 csi-rs ports of the gNodeB.
From this the gnodeB is able to constitute the air interface matrix and calculate the precoding matrix.
Not only the precoding matrix but also the beamforming matrix.
How precoding matrix, equalizer matrix and diagonal matrix is calculated from air interface matrix is explained here:
Precoding matrix is not but phase shift by which layers are to be mapped with the antenna port:
Y = WX, y is AP, W is PM, X is layer, helps in deciding.
So you are saying Beamforming Matrix is for finding the UE location?
Yes, but what about if the UE moves after RACH?
Beamforming matrix is not for UE location but for signal forming at UE side.
Beam refinent will help here, P2 procedure.