you forgot one major information:
which vendor are you working with?
– are those concentric cells (inner zone / outer zone) or multiband cells (1800 zone and 900 zone) ?
– what is the major cause of the HO? (you should find the split of handover causes in your qos stats)
List of Intracell HO possible causes:
Interferences for non AMR calls
Interferences for AMR calls
TCH vs PDCH resources management
And that’s it, for alcatel. Perhaps other vendors propose additional causes.