Hi Experts,
Does beamforming always use MU-MIMO in 5G?
It can be SU-MIMO or MU-MIMO.
We need to activate MU-MIMO using switch parameter.
Once MU-MIMO activated then users coming in pairing depend on below factors:
- Spatial distance
- CQI reported
- Number of layers configured
If condition satisfied then only UE come in pairing called MU-MIMO.
By spatial distance I mean correlation < 1, i.e. UE are separated not clustered.
No, there is beamforming also for SU-MIMO.
Beamforming always mean number of ssb > 1.
If you have single SSB then it’s not beamforming.
That means it can be both, right?
Yes both but remember without activation of MU-MIMO it will not work.
Default always SU-MIMO.
Yes.
Normally what is recommended?
Should we enable MU-MIMO?
For high Traffic with PRB utilization average over 80%.
Yes for PRB saving recommend, but Throughput can dip.
Seen with MU-MIMO big struggle to get user Throughput gain.
Pre/post kpi’s need to capture carefully to show gain.
So when MU-MIMO is not enabled, PDSCH/PDCCH resources will be divided among the beams?
Here are some god stats for LTE 16 PDSCH layers: Max number of DL PDSCH layers for MU-MIMO spatial multiplexing in a cell with high traffic.
Very difficult to pair 8 UEs for 16 PDSCH layers.
Yes sharing not there.
PDCCH resources not paired.
PRB multiplexing there.
Almost impossible.
We’ve done it, but required huge efforts.
For 16 PDSCH you need each 8 users stay a in single beam out of 8 beams.
Also need to be very close to gNB.
Sorry, didn’t understand.
I mean without MU-MIMO sharing not there.
With MU-MIMO PRB multiplexing there.
For PDCCH resources not sure sharing there or not.
Huawei has Mu-MIMO for PDCCH as well.
4 layers for PDCCH.
In 5G I mean.
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Please give brief for PDCCH MU-MIMO.
How it works?
Algorithm and criteria.
I am also struggling to understand how you can have 4 PDCCH layers with 16 PDSCH layers for 8 users, each one in a different beam…