are you talking about intracell HO roc ?
or internal & external outgoing HO roc ?
if intracell, then you will also measure high INCOMING HO CONGESTION (check the indicator TCH HO CONGESTION RATE). i’d say that your parameters are not optimized and you are currently pushing too many MS into the inner zone.
You could try to :
1/ increase the RXLEV DL ZONE and RXLEV UL ZONE by +2 or +3dB (or more)
or
2/ increase the ZONE HO HYST DL and ZONE HO HYST UL by +2 or +3dB (or more)
Please, what are you current settings for these 4 parameters ?
If you don’t want to touch the parameters, please activate the EN LOAD BALANCE.