Whats is the difference between DC (Dual Connectivity) and CA (Carrier Aggregation)?

5G NR
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21

From UE perspective there’s a chance the SW supports both and technically it’d be viable to activate or deactivate support to SA and/or specific bands via OTA.
I just don’t think business model would drive us there.

22

Let me relate this with example.
LTE Baseband supports all LTE Bands and CA but limited by RF.
Similarly NSA UE does support piggybacking NR messages but limited by some other factors to not support NR SA.
Which may or may not be updated by UE vendors, thus NSA and SA might need to coexist.

23

In US there are many cases with NSA and SA cells on same tower but don’t know actually how it works.

24

It works. UE gives priority to SA.

25

Yes, but what does it happen with UEs that do not know SA?
So there will be 2 AAU on tower for one sector: one for SA and one for NSA?

26

They camp on LTE and add SCG for 5 NR not SA capable UEs won’t find PSS/SSS while scanning raster.
SA can be collocated or not.
And there’s DSS using SA as well.

27

Right.
So all necesary information of SA will be delivered to UE via LTE.

28

I think even NSA UEs have to sync and measure PSS and SSS for B1 meas report:

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29

Not sure if I follow :slight_smile:
SA UE will camp first on an SA cell and get rrc from there.
Is the question how an SA capable UE that camped on LTE first becomes aware of SA for mobility procedures?

30

It depends on deployment strategy also.
For Eg: TMO deployed SA in US where NSA is already there But the SA Ue camps on SA network only when mid band LTE (sub3Ghz) coverage is not present.
If it is present then NSA will be working with LTE as anchor.

31

There is SIB in LTE for that, and also Redirection is always an option.

32

For acquisition purposes, on an NSA carrier no RRC from there.

33

Question if there will be 2 cells for same coverage: one with sa coverage one with nsa coverage.

34

UE RAT search will depend upon SIM and UE prioritized RAT search order as well.

35

UE will camp on SA and retrieve RRC there.

36

Very true. Best practice now is to try SA first.

37

Indeed, but searching SA first without knowledge of availability might cause delay as well, other sides of the coin.

38

My query is what NSA UE will do if there on only SA coverage.

39

Let’s relate this with example, NSA to SRLTE.
Does UE search CDMA first or LTE first, depends upon SIM PLMNawct file and UE RAT priority

40

Nothing. Stays in LTE.