6 owo203030 wcdma ran call drop kpi and relative counters ra

WCDMA RAN Call Drop KPI and Relative

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Confidential Information of Huawei. No Spreading Without Permission


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� Generally, the release of RABs or IU is initiated by the CN. However, in the following conditions, the RNC triggers the release.


conditions, the RNC triggers the release.

� If RNC triggers IU release or RAB release ，and the cause is:

� User Inactivity

� Normal Release

� Successful Relocation

� Network Optimization

� UE Generated Signaling Connection Release

� In some abnormal cases, for example, when an AAL2 link over the Iu interface is abnormal, the RNC sends a RAB RELEASE REQUEST message to the CN to trigger the release of RABs. These kinds of RNC-Triggered RAB Release are taken as call drops.


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� Call drop KPI should be calculated for CS and PS domain separately.


� For analyze, there are call drop counters based on reasons, including RF reasons and Non-RF reasons.

� For CS domain, there are call drop counters for AMR service and video call service.


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� If the RNC has sent an IU RELEASE REQUEST message or a RAB RELEASE REQUEST message with the release cause of "Radio Connection With UE Lost" or


REQUEST message with the release cause of "Radio Connection With UE Lost" or "Failure in the Radio Interface Procedure", RNC measures these by RF reason counters.

� After the RABs have been successfully set up, the RNC releases the related RABs if an exception occurs .These abnormal released RABs include all released RABs except the following causes: Normal Release, RF Failures . For example, the AAL2 link on the Iu interface becomes abnormal, RNC measures these by abnormal reason counters.

� After call drop , according to different services, RNC measures the counters for AMR services and video call services also.

� The counters for normal RAB release are used to calculate call drop rate.


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� Similar counters are defined for PS services based on release reason and Max bit rate.


rate.

� Because of some specific UE, UE signaling trigged releases are not taken as call drop. That means “VS.RAB.Loss.PS.Abnorm.RNC” exclude UE signaling trigged releases .


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� After call drop , according to different services, RNC measures the counters for AMR services and video call services.


services and video call services.

� Here , the RNC level “service normal releases” is the sum of the cell level counters.


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� RNC level AMR call drop rate:


� RNC level VP call drop rate:

AMRs.CS.Norm.VS.RAB.Los NCs.CS.AMR.RVS.RAB.Los

NCs.CS.AMR.RVS.RAB.Los

∑+

RB.64l.CS.Conv.VS.Norm.Re 4K.RNCs.CS.Conv6VS.RAB.Los

4K.RNCs.CS.Conv6VS.RAB.Los

∑+


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� For PS domain, there are call drop counters for services with different typical rates.


� For analyze, same as the CS counters ,there are call drop counters based on reasons, include RF reasons and Non-RF reasons.


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� Similar counters are defined for PS services based on release reason .



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� Similar counters are defined for PS services based on release reason and Max bit rate.


rate.

� Because of some specific UE, UE signaling trigged releases are not taken as call drop. That means “VS.RAB.Loss.PS.Abnorm.RNC” exclude UE signaling trigged releases .


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� After a call drop, according to the call drop reason, RNC measure these counters in the best cell.


the best cell.

� The call drop reasons include RF reasons , abnormal reasons.


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� RF call drop may be caused by several reasons:

RLC layer reset


� RLC layer reset

� Physical layer Uplink Synchronization Fail

� Failure in the Radio Interface Procedure

� Based on these reasons, three counters are defined.


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� Cause of "O&M Intervention“: by LMT, any user or service can be released manually.


� Cause of "RAB pre-empted“ and “CELL Congestion” are related to load control algorithm.

� Cause of “Iu Interface AAL2 Link Failure” is related to the Iu transmission.


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� After a call drop, according to the call drop reason, RNC measure these counters in the best cell.


the best cell.

� The call drop reasons include RF reasons , abnormal reasons.


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� RF call drop can be caused by several reasons:


� RLC layer reset

� Physical layer Uplink Synchronization Fail

� RRC layer procedure failure

� Based on these reasons, three counters are defined.

� Because of PS traffic and signaling are configured with RLC AM ,so “RLC reset” for PS include SRB reset and TRB reset, measured by “VS.RAB.Loss.PS.SRBReset” and “VS.RAB.Loss.PS.TRBReset”.


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� The counters for abnormal failures are similar with the CS counters.



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� Missing neighbors may cause RF call drops.



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� If the RAB is set up for the HSDPA service, the RNC measures the items in the HSDPA cell that the UE camps on after HSDPA call drop.


HSDPA cell that the UE camps on after HSDPA call drop.

� The call drop reasons could be RF or abnormal (Non-RF) reasons.

� Because of some specific UE, UE signaling trigged releases are not taken as call drops, these releases are included in “VS.HSDPA.RAB.Loss.Norm”


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� “VS.HSUPA.RAB.Loss.Abnorm” , this measurement item takes statistics of the number of all HSUPA RABs abnormally released by the RNC in a cell.


number of all HSUPA RABs abnormally released by the RNC in a cell.


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6 owo203030 wcdma ran call drop kpi and relative counters ra

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