Possible reasons for 100% Inter HO Prep Fail?

Mobility
21

Source node is new node.
Target are Old.
ENBID is same

22

For Ericsson system, 2 features can affect HO preparation:

  1. problematicCellDetection = true. If a relation becomes with bad HO success rate, it will start blocking the relationship.

  2. UL trigger interfreq HO. If SINR is bad in the target node, HO preparation will fail.

23

Let me check these.

24

Also when such kind of issue occurs.
Please enable S1/uu/x2 traces and check for the exact failure reason.
Cause of failure, that will help you alot for troubleshooting.

25

TAC, eNodeBId and MME definitions are the first things to be checked in such cases when they are returning 100% preparation failures.
Incase this is not the issue, RBS restarts may also fix the issue incase of anything related to transmission.
Last but not the least neighbor recreation with the help of ANR mostly solves the issue clearing the possible discrepancies.

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  1. Disable Auto X2 defs and remove termpoints.
  2. Delete the external cells and neighbors.
  3. Enable auto X2 and confirm termpoints are created properly.
  4. Enable ANR and check TAC, Mme ID, eNb ID, cell Id and PCI are configured as per LLD.
    It worked for a similar issued faced in 2014.