CCE when gNB pair 4 UE in MU-MIMO

RAN
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1

Hi Experts.
In case of MU-MIMO, if the gNB pair 4 UEs (say 4 layer), then what about PDCCH?
Will each layer share the same CCE or there will be different CCE for each UE?

2

Huawei has 4 layers for PDCCH MU-MIMO.

3

Good question.
My understanding is that MU-MIMO will share FD resources for PDSCH only, but PDCCH will still work same as legacy way. (Different CCE resources for different users).
However, I’m not sure.

4

PDCCH 4 beams are available even in LTE Huawei.
If we have only 1 single beam same like reference signal beams, it will have the same CCE capacity and coverage.
But if we would like to use MU MIMO on PDCCH to increase CCE capacity, option is available in Huawei 4G and 5G.

5

Yes. If I don’t activate this we have to allocate CCE for every UE, right?

How exactly will it work. Suppose I have 8 layers and serving 8 UEs with RI=1?

6

I need to check as PDCCH beams is also having separate weight to distinguish beam based on user location.
Same CCE allocation to different user on different PDCCH beams to increase the control channel capacity.

7

Yes of course. Both of these we have to use simltaneously.
Only PDCCH beams are possible without MU MIMO to enhance the CCE capacity?

8

if you are talking about 5G, I don’t use PDCCH beams as its having enough capacity in frequency domain to serve MUBF with 16 users which is very difficult practically.

9

Yes, but in future we may need to use this.

10

As per LTE MU-MIMO we have sector beam listen by all UE in cell for common control channels and UE beam using PDSCH layer for particular UE in pairing.
Never seen PDCCH resources shared among UE which are in pairing.

11

As per my understanding, we will not require to use as high MUBF layers are having multiple factors (user location, CQI, Data demand, beam weight).
So even if you reach high layers it will prove that users are having good condition to participate in MUBF and will have less CCE requirement due to less agg level.

12

Maybe PDCCH is still using 1 wide beam, all 4 UE read 1 PDCCH beam, different CCE for them, then they use 4 PDSCH beams.

13

Yes exactly like sector beam scenario.
But I remember in some discussion it’s mentioned Huawei having PDCCH based beamforming as well.
May be then CCE multiplexed among users.

14

That is 4 PDCCH layers MU-MIMO.

15

Ok :+1: good feature with Huawei only.