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1. LTE Call Drop Diagnosis
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2. LTE Call Drop Diagnosis
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3. LTE Call Drop Diagnosis
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4. LTE Call Drop Diagnosis
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5. LTE Call Drop Diagnosis
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6. LTE Call Drop Diagnosis
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7. In the second scenario, if 4 seconds prior to the reception of RRC Connection Release there
LTE Call Drop Diagnosis
were no RLC layer data transmitting call drop will not be counted. This consideration is
because of some special scenario, e.g. data adapter user may plug out the data adapter
without detaching it when service is done. In this case call drop is not counted.
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8. LTE Call Drop Diagnosis
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9. In FTP downloading or uploading (or packet injection), if there is not manual intervention
LTE Call Drop Diagnosis
the throughput should persist. If it suddenly dropped to bottom, call drop very much
possibly occurred.
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10. LTE Call Drop Diagnosis
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11. LTE Call Drop Diagnosis
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12. L.E-RAB.AbnormRel is the statistics of total number of eRAB abnormal releases of the cell
LTE Call Drop Diagnosis
in the eNodeB based on data transmission of different causes and users.
L.E-RAB.NormRel is the statistics of total number of eRAB normal releases.
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13. Scenario 1: as shown at point A in the left figure, when the eNodeB sends an E-RAB
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RELEASE INDICATION message and the cause value is not “Normal Release”, “User
Inactivity”, “CS fallback triggered” or “Inter-RAT redirection” this counter is incremented;
Scenario 2: as shown at point A in the right figure, when the eNodeB sends a UE CONTEXT
RELEASE REQUEST message to the MME all E-RABs of the UE will be released. If the cause
of release is not “Normal Release”, “User Inactivity”, “CS fallback triggered” or “Inter-RAT
redirection”, the counter will be incremented.
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14. LTE Call Drop Diagnosis
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15. LTE Call Drop Diagnosis
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16. LTE Call Drop Diagnosis
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17. LTE Call Drop Diagnosis
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18. According to the release cause value in message E-RAB RELEASE COMMAND(E-RAB
LTE Call Drop Diagnosis
RELEASE INDICATION) or UE CONTEXT RELEASE COMMAND(UE CONTEXT RELEASE
REQUEST), counters for various abnormal release causes count.
When the release cause is faults at the radio network layer, L.E-
RAB.AbnormRel.Radio counts.
When the release cause is faults at the radio transport layer, L.E-
RAB.AbnormRel.TNL counts.
When the release cause is network congestion, L.E-RAB.AbnormRel.Cong counts,
including the abnormal releases caused by pre-emption and resource congestion.
When the release cause is handover failure, L.E-RAB.AbnormRel.HOFailure counts.
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19. LTE Call Drop Diagnosis
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20. LTE Call Drop Diagnosis
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21. ANR：Automatic Neighbor Relation
LTE Call Drop Diagnosis
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22. LTE Call Drop Diagnosis
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23. LTE Call Drop Diagnosis
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24. LTE Call Drop Diagnosis
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25. LTE Call Drop Diagnosis
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26. LTE Call Drop Diagnosis
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27. In corner effect, because the signal of the source cell drops rapidly, the UE does not have
LTE Call Drop Diagnosis
enough time to complete the signaling process with the eNodeB, call drop occurs.
In needle-tip effect, it leads to call drop that the signal of the source cell drops rapidly or
that of the target cell increases rapidly and then decreases sharply.
In the view of signaling process, usually the UE reports neighbor cell’s A3 MRs and the
eNodeB has received it, then HO command is sent out but the UE cannot receive it. At this
time if there is UE’s context in the target cell and the reestablishment succeeds, call drop
may not occur.
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28. In the view of signaling process it is found that just after a HO the UE starts reporting new
LTE Call Drop Diagnosis
MRs and a new HO is triggered. Because there are some more reconfiguration messages
(CQP report mode, sounding, etc.) need to be delivered after the HO, in the ping-pong
area it is susceptible to call drops due to time-out of these commands.
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29. LTE Call Drop Diagnosis
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30. LTE Call Drop Diagnosis
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31. LTE Call Drop Diagnosis
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32. LTE Call Drop Diagnosis
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33. LTE Call Drop Diagnosis
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34. LTE Call Drop Diagnosis
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35. LTE Call Drop Diagnosis
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36. In general, the selection of top cells complies the below rules:
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Top cell’s call drop rate KPI is worse than the average of the whole network.
Rank the cells by the absolute call drops in descending order.
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37. LTE Call Drop Diagnosis
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38. LTE Call Drop Diagnosis
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39. The value range of CQI is from 0 to 15, the bigger value the better coverage.
LTE Call Drop Diagnosis
The value range of MCS of PDSCH and PUSCH is from 0 to 31, the bigger value the better
coverage.
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40. LTE Call Drop Diagnosis
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41. LTE Call Drop Diagnosis
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42. LTE Call Drop Diagnosis
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43. LTE Call Drop Diagnosis
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44. Congestion and user number related counter:
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L.Traffic.User.Avg: Average number of users in a cell
L.Traffic.User.Max: Maximum number of users in a cell
L.LC.ULCong.Num.Cell: Number of times uplink congestion occurs in a cell
L.LC.DLCong.Num.Cell: Number of times downlink congestion occurs in a cell
L.LC.ULCong.Dur.Cell: Duration of uplink congestion in a cell
L.LC.DLCong.Dur.Cell: Duration of downlink congestion in a cell
L.LC.User.Rel: Number of GBR service releases due to congestion in a cell
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45. Outgoing handover counters between two specific cells
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L.HHO.NCell.PrepAttOut: Number of outgoing handover attempts between two
specific cells
L.HHO.NCell.ExecAttOut: Number of outgoing handover executions between two
specific cells
L.HHO.NCell.ExecSuccOut: Number of successful outgoing handovers between two
cells
L.HHO.Ncell.PingPongHo: Number of ping-pong handovers between two specific
cells
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46. LTE Call Drop Diagnosis
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47. LTE Call Drop Diagnosis
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