The intracell HO can be caused by :
– interference (UL or DL)
As any handover, the process of this HO can be divided into two parts : the preparation phase and the execution phase (respectively, the request is validated as an attempt, and the attempt becomes a success).
A preparation failure is due to congestion in the cell or a hardware failure (trx, combiner, sum, abis, bsc..).
An execution failure is due to radio problems (interference to high in the target frequency, radio link is lost, …), or again, a hardware failure. Execution failure can be “saved” by a Reversion to the Old Channel (ROC).
I hope it’ll help you…