Hello Huawei LTE Experts!
I have the ANR active in the LTE network, the detail is that I have some utranncell with rncid 50, but in the RNC, I see that the 3G cell is at a rncid 60.
The question is: why does the ANR not change it to 60?
Is it convenient to remove those utranncell with incorrect rncid and let ANR add them again?
Because the utrannfreq are created.
You must correct all information stored into UTRANEXTERNALCELL (LTE MO), otherwise still will compare all the measured info into UTRANEXTERNALCELL.
And will add with these info or will not add if the measurement does not meet with EXT MOs.
This rules also valid all the type EXTERNALs for any of type of addition by ANR or SON etc auto tools.
If the rnc id in utranexternacelcell (mo LTE) is incorrectly configured, could there be a problem?
There can be a few different problem.
For example
These are just some of examples, wrong RNC id, CID, PCI / SC can raise many different type problem if not defined properly and correct in any type of EXTERNAL / NRNRELATIONSHIP etc.
Because if Cell A is measured cell B and if get right and dominant values from cell B, before addition into INTRA - INTER - INTERRAT etc neighbor relation, comparing within external list values and if it is have been meet and adding.
Otherwise couldn’t adding because it can be because of conflict or confision and deciding to not add it.
Note: This is general approach, some operator do not interest to use it, if don’t have many crowded cities 
Remove the relation and the external cell. ANR should be able to pick up the new neighbor with the final config.
Updates in ANR are more difficult to happen better remove everything and ANR will add it within seconds.
You can do it in night and activate Fast ANR for few hours, that should be good.
I did this last night and it worked, the ANR added them with the correct rnc ids.
The strange thing is that the CSFB remains stable above 99.5% before and after the corrections.
Some users may notice the improvement, as the complaint was that voice calls were not originated on 3G and were stuck on LTE, but only with iPhone devices, very strange.
If the CSFB is through blind HO, then the neighbors are not important, only the UTRANNFREQ.
Maybe there are some missing frequencies or the priorities are not well set.
I am just curious how ANR would know the correct RNC id…
You must have corrected first externalutrancell.
The ANR can add the external cell.
Basically when UE is measuring 3G it reports PSC, if the eNB does not recognize a PSC it will ask the UE to send cell information and with that the external cell is created and then the neighbor.
In cell information there is no RNCID.
Everything in the external cell is reported by the UE, cell id, rncid, lac, rac etc.
But after eNB requires to collect that.
Do you know from which IE / message / SYSINFO the UE is able to inform eNodeB of the rncid of the cell?
Is not a common message, don’t remember how is the name for 3G cell but to add lte neighbors from different frequency the name is ECGI.
If the eNB does not recognize a PCI it will ask the UE to report the ECGI of the cell.
Same process applies for 3G.
I guess in 3G the name is CGI.
ECGI is clear: PLMN + enodeBId and cellid would uniquely identify a cell in this world.
But for 3G I am not sure the UE would know the RNCid.
I thought blind delivery just bypassed the radio levels, but relationships (utranncell) still needed.
You are right CGI usually don’t include the rncid, because with the PLMN the LAC and the cell is enough to identify the 3G cell.
However, I got this from ANR documentation in Huawei, I think Huawei for ANR is able to request the rnc id from UE, and I am 100% sure that ANR is able to create UTRANEXTERNALCELLS which include the rncid.
Step4 read BCH… I am just curious in which IE / message / SYSINFO is the rncid.
Maybe cellid = RNCID + cellid
But this depends on how operator define cell id.
I think it should be read somewhere, if I remember well, I test on time using Genex Probe without importing EPT to see what parameters the software was able to pick up and I think I was able to see the rnc id.
So it looks like CGI is based on rncid and cell id.
But I never heard of rncid to be sent to UE in any IE / message / SYSINFO.
So I am curious to know how UE knows the rncid of the 3G cell.
It can work both ways depending the configuration, look one the options you have in this flow.
During a POC, I remember we wanted to check how fast the CSFB can be.
Without neighbors it took around 10s sometimes it failed, adding only 1 dummy neighbor, the performance improve to 4s, so adding the full number of neighbors may not be required.
