Intra-frequency Handover LTE

RAN
1

Hello experts,

Please could you tell me why the Handover is not decided even if the A3 event cobditions are satisfied and the UE is sending the measurment report several time, but The EnodeB is not taking any decision for handover, what could be the reasons?

2

Please can someone advice me for this issue, I am encountering this issue on several sites, especially in intra-frequency intra-enodeb

Nb: working on Huawei Equipment

3

LTE UE event Measurement Reporting-Event A1,A2,A3,A4,A5,B1,B2 (linkedin.com) You should get the answer from this article.

4

@Adil possible reasons
1- neighbor relation is not defined
2- relation is defined but HO is configured as not allowed

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5

Thank you for your feedback @Wendy and @O.B.
@O.B the neighbor relation is defined and the handover is allowed.

Could be other reasons than those 2?

6

Hi,
please check A3 offset and hyst and time to trigger
check resource in target cell ,one reason of this issue can be high utilization in target cell.

7

check if there is ping between serving cell and colocated nb cell (below counter)

L.HHO.Ncell.PingPongHo

8

I found that the reason could be that the cell have 2 neighbors in the neighboring table with the same PCI and the same EARFCN, so the serving cell does not know what is exactly the target cell, so the handover is not triggered. But I am not sur of that

9

That makes sense
please what was the reason?

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10

The reason was PCI conflict. When the A3 event is triggred the UE reports only the PCI and earfcn of the target cell, when the source enodeb reads the message it check the pci and the earfcn reported and search enodeb ID of that pci and earfcn in its neighboring table, if it founds two or more different enodeb IDs, the HO will not occur. Because the source endb does not know to which target it will send the HO request.

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11

In such condition, there is a feature/ parameter by which enb sends a request to UE to send ecgi also.
As pci-earfcn was same in both the cells and enb gets confused to decide target cell, ecgi solves this confusion and enb sends handover msg to correct target.