Why different termination types in NRDC when both RATs are NR only?

5G NR
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#1

Hi Guys.

I have a query specific to NRDC scenario.

We can have MN or SN terminated bearer in NRDC.

But what would be the need for having different termination types in NRDC when both RATs are NR only?

Hence both PDCP would have similar functionality.

Can you think of any reason for this?

#2

It can be use for CA purpose I think.

#3

Here NRDC will work the same like ENDC, I mean to say only MN or either SN have PDCP (single PDCP).

PDCP split happens and MN and SN RLC layers received Data accordingly.

#4

But what would be the need to have different termination point since the RATs are same in NRDC?

Hence PDCP will work similarly.

So how would MN terminated behave any differently than SN terminated?

#5

We’ve got same scenarios in LTE DC.

One of the best example that we can consider for NR-DC:

  • MN can work in FR1 (Macro cells) and support e.g. VoNR and SN can work in FR2 (small cells) and has got more bandwidths.

  • So MN bearers could be 5QI-5,5QI-1 and SN Bearer here can act as solit bearer and can be e.g. 5QI-9.

  • Therefore, NR-DC in this case can be supported by two frequencies FR1 and FR2.

  • And in the case of split bearer(SN PDCP is the splitter), both MCG and SCG contribute for CA (Carrier Aggregation).

#6

Yes, correct!

#7

Thanks!

What I am trying to understand is that let’s say I only establish termination point of all my MCG, SCG or Split bearers as MN terminated.

What difference it might create in my operation as opposed to them being SN terminated?

The whole bandwidth difference between FR1 MN and FR2 SN would be at the MAC and PHY, higher layers won’t any any impact on how much bandwidth the two cell have.