What are the differences between Execution and Preparation in LTE HO

This is not the degration of HO. It’s due to ANR function activated, before that L.IntrafreqHO.NoNRT has value because many neighboring cells are missing, not included in the neighboring table.
And also HO preparation success not equal HO execution attempt.

I see what you mean here, but as you can observe from the next graphs, SuccExec/AttExec stabilised from the ANR activation.

ANR can: add missing, remove redundant, correct external cells. So, after anr works, hosr is improved.

Hi, do you have any observation that ANR works better in adding cells but not best performance observed while removing cells?

Removing redundant neighbors mean neigjbors with very few HO attempt during a period, then not neccessary to keep. Rmv them to add other cells, bcs max neighbor is 32.

For Ericsson we faced a challenge that suppose a gerancellrelation is created by ANR, after some days if I change 2G LAC, the Eutran to Geran cell relation is not getting updated by ANR.
Ideally the old relation should get deleted and new relation should form with updated CGI.
Similarly, if I change TAC of a particular cluster, the external eutrancellrelation still continue with old TAC. We have to delete relations and recreate through ANR.
Is it same for other OEMs as well?

In Huawei, it can be updated. You must enable anr for neighbor correction, set period of time.
After that period, ANr will check and update.
Normally about 1 week.

Ericsson also we can set ncellremovetime, we keep it to say 1 day.
But the external neighbor deletion does not function exactly as efficiently as neighbor addition.
We have raised it to PDU, let’s see what they reply.