Increase Number of UEs supported per TTI in 5G

Hi All,
If we increase the number of UEs supported per TTI in 5G from 16 or 32 UEs/TTI (to let’s say 64 or 128 UEs/TTI), then how will it impact the L2 or upper layer processing?
What could be the bottleneck?
Basically If I change UEs/TTI from 8 to 64 given a fixed resource allocation.

Per slot in 5G.

Yes, per slot.

As per my knowledge till date there is no parameter to control no of users in 5G per slot.
It’s fixed 1 only.
Others can comment.

Yes there is no parameter.

What my question is If I schedule 8 UE/slot vs 64 UEs/slot or 128 UEs/slot, what becomes the bottleneck for L2 and upper layers.
Is it the storage, processing?
Can anyone with L2/L3 expertise comment?

In my view no of PRB can be bottleneck.
From processing side there is no as such bottleneck seen from hardware side used.
If we have proper ecpri link between Base Band and Radio module.

I think PDCCH capacity is can be bottleneck.
If UEs are in poor radio condition, then due to high AL requirement, we cannot schedule as many user in 1 TTI.

PRB is also possible, but in NR with very high BW less chances.

Yes as of now for NR high capacity site scenario not there, even we don’t have any single live site for NR :grin:

If I have 8 UEs I schedule 32-35 PRBs per UE where if I have 64 UEs.
Then I schedule 4-5 PRBs per UE.
Given the full 100 MHz bandwidth, I can put 64 DCIs with agregation level 1-2, given that the channel is very good.

In LTE we seen limitation of PUCCH resources as well with high users.

Think it’s L2 processing.
Higher UEs per slot is impacted by HARQ feedback processing, etc.
So in my view higher UEs per slot is L2 processing capacity.

Can you please put little more details?

Not an L2 expert, but came across this request in one of my projects.
From development perspective, tracking all HARQ threads in gNB L2 is extensive processing task. Higher UEs need higher buffering, processing, scheduling, etc.