What will happen when UE sends neighbor cell measurement for HO but that neighbor cell is barred?

Question

Does UE reports neighbor cells in order of RSRP in measurement report of A3 event ?

Answer 1

Hi Veer,
In LTE, if a cell is barred or not, can be decided by two factors.
1. If the parameter cellBarred, which is usually broadcasted in SIB1, is set to barred, then that cell clearly says that it is unable to accept any calls, including the emergency as well as special access class calls. So, source eNB shouldn't take a HO decision in this situation.
2. The parameter acBarringFactor indicates the max value of the UE generated access class, that the eNB can accept. If the value is set to P00 and the same is broadcasted in SIB2, then also the cell is kind of barred. Now, it is completely vendor specific, whether to take HO decision or not, based on this parameter. If source doesn't consider this param while taking HO decision, then, probably source will initiate HO, but, it will fail at target and UE can try to re-establish back to source.

Thanks,
Sourav

Answer 2

In actual approach, these Barred/unbarred info is not accessible at the time of measurement reporting especially when you have configured for any of the events and reporting set as "for strongest cell". This is because, based on the measurement configuration for the purpose of HO, UE may not read SIB1 of neighbor/target cell. (Please note that report for CGI is not mandatory for HO).

Such conflicts are resolved eNodeB itself:
1) if X2 link already established, when source eNodeB sends X2AP Handover request command to target enb, target enb will send X2AP handover request failure with cause "Cell not Available"..
2) If X2 link is not available, then it is possible that, target enb may send X2 setup failure itself if none of its cell are available/active as response to X2 setup request from source enb.

looking at the date when this question was posted, I Hope you have already acquired this info :-):-)..