On a NSA 3x, which scenarios do you see NR-CGI being shared with the MME?
The only one I think is ANR UE-based for NR missing neighbors, but that would require SIB1 to be broadcasted on NR.
PS: NR-CGI is defined on S1AP.
But there’s no SIB1 in NR in NSA.
Everythign is delivered via RRC Connection reconfig in 5G.
Precisely, current implementations no SIB1 is being broadcasted.
Does that means it works only in SA the ANR addition by CGI?
Well, the spec doesn’t prohibit the SIB1 broadcast on NSA (sure, vendors don’t do it because you don’t need to), so thinking out loud, maybe the vendors will start thinking about broadcasting SIB1 once the gNB is fully prepared to SA, then we will start seeing CGI-based features.
But this is my opinion based on nothing. LOL!
I don`t have access to vendors roadmaps, for instance.
I seen in NSA3x as well for 5G CGI reported.
Do you see on NSA 3x the NR cell broadcasting SIB1 to allow ANR UE based?
Or do you see any other ANR feature based on PCI reports?
You may have ANR features without requiring the UE to read the CGI of the target cell.
But this ones requires OSS-side implementations.
It’s based on PCI added under NR meas object then using report config having inter rat r15 event periodical.
Purpose cgi report.
But for that you need SIB1 to be reported, are you aware of vendors already broadcasting SIB1 under NSA 3x?
Yes what info SIB1 contain for NR I am not aware.
SIB2 I know having primary PLMN IE required for 5G logo.
Are you talking about SIB1 after sgnb addition or at LTE side?
If you’re talking about SIB1 after sgnb addition then it’s part of RRC connection reconfiguration.
What i know no SIB1 in NSA3x, only MIB.
I was talking about NR SIB1 which will holds the info to build the NR-CGI. Sorry, I should have mention it…
Let’s assume for instance, the UE hasn’t the NR leg added yet, but it was configured with B1 to measure possible candidates. It measures a PCI from a target NR cell which is not part of the IRAT neighbor list of the LTE cell which it is camped at, thus, no addition of the NR PSCell is performed since there is no X2 between the serving LTE and the measured target NR cell
Question: how would the eNB figure out the complete information for this possible NR neighbor?
From an analogy with LTE, you have two options: either a fully UE-based ANR feature which will command the UE to read NR SIB1 and return its NR-CGI to perform the addition, OR, you will have some ANR based on OSS data, let’s call a vendor solution, which will map this PCI to some possible NR cell.
It’s difficult to do this based on reported PCI.
There can be tens of cells with same PCI, OSS may need lat long to calculate which one is closest to the serving cell.
Agreed! It would be a caos!
I guess It can be done somehow, but it would sux
From the early days of LTE this was precisely the problem. I remember for Nokia, for example, the ANR IRAT to UMTS fully UE based was the last one to be ready, before this, PS HO to UMTS was a freaking disaster!
Yes, correct. Actually old method is PCI IP address mapping.
New one is fully UE based ANR where we have concept of strongest cell reporting then reporting cgi of that cell to add neighbor.