Call Drop Rate (VoIP)
Description
The Call Drop Rate (VoIP) KPI indicates the call drop rate of the VoIP services in a cell or radio network. A VoIP call drop occurs when the VoIP E-RAB is abnormally released. Each E-RAB is associated with QoS information. Usually, the QCI of VoIP services is 1.An E-RAB consists of a radio bearer and a corresponding S1 bearer. Any abnormal release of either bearer causes a call drop. A release is defined as abnormal by its release cause according to 3GPP TS 36.413.
Abnormal E-RAB releases can be classified into the following two scenarios, as shown in Figure 1.
Figure 1 Abnormal E-RAB release
- Scenario 1: When the eNodeB sends an E-RAB Release Indication message to the MME, the abnormal E-RAB release counter is incremented if the bearer to be released carries data and the release cause is not "Normal Release", "Detach", "User Inactivity", "CS Fallback triggered", "UE Not Available for PS Service", or "Inter-RAT Redirection".
- Scenario 2: When the eNodeB sends a UE Context Release Request message to the MME, the abnormal E-RAB release counter is incremented if the bearer to be released carries data and the release cause is not "Normal Release", "Detach", "User Inactivity", "CS fallback triggered", "UE Not Available For PS Service", "Inter-RAT redirection", "Time Critical Handover", "Handover Cancelled".
NOTE:
- Except for the preceding two scenarios, the normal E-RAB release counter is incremented.
- If the message contains several E-RAB ID IEs (in the E-RAB To Be Released List IE), the counter will be incremented for each individual E-RAB.
Definition
The Call Drop Rate (VoIP) KPI is defined in Table 1.| Name | Call Drop Rate (VoIP) |
|---|---|
| Object | Cell or radio network |
| Formula | VoIP_CDR = (VoIPERABAbnormalRelease/VoIPERABRelease) x 100% |
| Associated Counters | Call Drop Rate (VoIP) = [L.E-RAB.AbnormRel.QCI.1/(L.E-RAB.AbnormRel.QCI.1 + L.E-RAB.NormRel.QCI.1)] x 100% |
| Unit/Range | Percentage (%) |
| Note | None |
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