How are UE multiplexed when implementing UL MU-MIMO?

Hello.

Does anyone have knowledge about UL MU MIMO?
Is it deployed? And if yes does usually separate ue in fdm?
In other words: how are UE multiplexed when implementing UL MU MIMO?

For UL MU-MIMO UE will come in pairing if they are orthogonal.

Here single layer per UE used i.e. for 8 UE it’s 8 layer.

If UE come in pairing then eNB allocate same PRB to UE i.e. PRB multiplexing used.

But ratio of UE very less in pairing for Uplink.

Other conditions used UL SINR, PRB usage for UE in pairing in Uplink.

So 2 or more UE can transmit in same PRB same time?

What do you mean here by UEs are orthogonal?

Yes if UE’s come in pairing.

It means UE are spatially separated, so correlation < 1.