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View Full Version : Original PARAMETER CHECK LIST FOR HIGH CALL DROPS CELLS



rfexpert
2011-11-25, 05:35 PM
What is Call Drop?
The TCH call drop rate refers to the ratio of call drops to successful TCH seizures after the BSC successfully assigns TCHs to MSs. The TCH call drop rate can be measured from the following aspects:

TCH call drop rate (including handover)
TCH call drop rate (excluding handover)



Formulas for Call Drop including handovers:
TCH call drop rate (including handover) = Number of call drops on TCH/(Number of successful TCH seizures (signaling channel) + Number of successful TCH seizures (TCH) + Number of successful TCH Seizures in TCH handovers (TCH)) x 100%


Formulas for Call Drop excluding handovers:
TCH call drop rate (excluding handover) = Number of call drops on TCH/Number of successful TCH seizures (TCH) x 100%

Parameter Check list for Call Drop:
These parameters are common for all the vendors the only difference is its name will be different.
The settings of some parameters on the BSC and MSC sides may affect the TCH call drop rate. If the following situations occur, the TCH call drop rate may increase:
1. The parameters SACCH Multi-Frames and Radio Link Timeout are set to too small values.
2. The parameter RXLEV_ACCESS_MIN is set to a too small value.
3. The parameter RACH Min.Access Level is set to a too small value.
4. The parameters Min DL Power on HO Candidate Cell and Min Access Level Offset are inappropriately set.
5. The length of timer T3103 (this timer is set to wait for a Handover Complete message) is set to a too small value.
6. The length of timer T3109 (this timer is set to wait for a Release Indication message) is set to a too small value.
7. The length of timer T3111 (this timer specifies the connection release delay) is set to a too small value.
8. The length of timer T305/T308 is set to an invalid or too great value.
9. The parameter TCH Traffic Busy Threshold is set to a too small value.
10. The parameter Call Reestablishment Forbidden is set to Yes.
11. The parameters related to edge handover are inappropriately set.
12. The parameters related to BQ handover are inappropriately set.
13. The parameters related to interference handover are inappropriately set.
14. The parameters related to concentric cell handover are inappropriately set.
15. The parameters related to power control are inappropriately set.
16. T200 and N200 are set to too small values.
17. Some neighboring cell relations are not configured.
18. The parameter MAIO is inappropriately set.
19. The parameter Disconnect Handover Protect Timer is set to a too small value.
20. The parameter TR1N is set to a too small value.
21. The parameters Software Parameter 13 and MAX TA are set to too small values.
22. If a repeater is used, the parameter Directly Magnifier Site Flag is set to No.