S’bahir Slim 🙂
if the BSC detects the best candidate cell is congested, then the cell is put in a “black list” (this list is associated to one communication only and is not used for other HO for other MS).
The black list is emptied after T7 seconds.
Keep in mind that the HO COMMAND is not sent in case of congestion : the BSC knows that the target is congested, so it doesn’t send the HO COMMAND. It will just go to the 2nd candidate and check if that one too is also congested.
As long as the HO is detected for the call, the BSC will try to find the best candidate which is not congested.