Improved call setup timing rates in 5G

Hi folks, a question on VoNR.
I read that call setup timing rates are improved for VoNR compared to LTE.
Given the fact that similar path is taken in both Core networks (eNB–>SGW–>PGW vs gNB–>UPF–> DNN), what aspect of 5GS that might be contributing to the lower call setup rates?

Is it due to the possibility of higher numerologies? Atleast for VoNR enabled cells, I think SCS for the P-cell is kept similar to the LTE to have the cell size comparable to LTE.

I don’t understand what other factor is coming in to reduce the call setup times.

Yes there is nothing more than that to reduce latency in 5GNR compared to LTE.

What value observed for call setup time?
How it is calculates, which 2 message difference taken?
For VoLTE it’s difference between invite and 180 ringing.
What about VoNR?

No idea, I was asked question like this, and I answerede that the metrics would be more or less same.
But, if we are going to compare the metrics between RATs, I think we can compare the same time diff between invite and 180 ringing.

Ok let me check more on this with call flow.

Same process.

:+1::+1: Thanks.
More or less same like VoLTE only registration phase then ringing phase.

VoNR is having better call setup time than VoLTE.
It’s due to some services like USSD activation are getting bypass or not happening in VoNR like in happened in VoLTE earlier.

Well, if we break-up the CST into RAN processes and other processes (that involve 5GC and IMS), I think Ran will have a smaller contribution.
Does it make sense?
Are we comparing VonR vs VoLTE CST aware that the core has a different architecture?

What difference in architecture for IMS?
P-cscf, I - cscf, s - cscf nodes not there?

5GC is different from EPC.

Yes AMF, UPF, SMF nodes there. I’m thinking why setup time reduced as mentioned?

I just don’t know how to establish a baseline without separating RAN and non-RAN contributions.

I think we can calculate in live logs by observing diff between invite and 180 ringing for 4 samples to conclude.

RAN improvement should be minor.
If compared with total CST (a couple of miliseconds maybe)? Not sure…

Yes, seems like.

It will not create any difference hardly latency improve by 1-2 ms.
Where as CST in seconds.

Yes, agreed.