KPI stands for Key Performance Indicators.
Based on KPI values we can access the performance of a network.
KPI’s are based on mathematical calculations and hence it is an important aspect for checking the quality of VoLTE service.
1. TAS KPI’s
This KPI will give us idea related to signaling related KPI such as shown below:
1. CSSR: Call Setup Success Rate
2. CST: Call Setup Time
3. MHT/ACD – Mean Holding Time/ Average Call Duration.
2. SBC KPI’s
This KPI’s will give an idea related to User Plane KPI such as:
1. RSR: Registration Success Ratio
2. Mute Rate
3. MOS Score
4. RTP Packet Loss
5. One Way Calls.
3. SGW/PGW KPI’s
This KPI’s will give an idea related to Bearer specific KPI such as:
1. IMS IP POOL Utilization
2. Create Bearer Success Rate
4. MME KPI’s
This KPI’s will give an idea related to Attach, Mobility and Paging related KPI such as:
1. VoLTE ASR: VoLTE Attach Success Rate
2. VoLTE PSR: VoLTE Paging Success Rate
3. Dedicated Bearer Activation Success Rate.
5. Radio KPI’s
This KPI’s will give an idea related to HO, Call Drops KPI such as:
1. VoLTE Call Drop Rate
2. SRVCC Success Rate
3. Handover SR: S1, X2
Now let us understand in detail regarding all the above KPI’s
VoLTE Control Plane KPI’s:
1. CSSR: Call Setup Success Rate (%)
2. CST: Call Setup Time (s)
3. MHT/ACD: Average Call Duration (s)
4. RSR: Registration Success Ratio (%)
1. CSSR: Call Setup Success Rate (%)
1. It is the indicator of how easily user is able to make a call.
2. Good range is 99+.
Category Of KPI: VoLTE service Integrity and Retainability
Source: TAS.
Formula: (MO call)
(Count of (Normal End Of Call + Call failed with User Behavior) )/ (Sum of all Call Attempts ) * 100%
2. CST: Call Setup Time (s)
1. It is the time to setup a call between the users.
2. It means, the time between the start of the call till it rings to the other user.
3. Good range is <2.5 s
Category Of KPI: VoLTE service Integrity and Retainability
Source: TAS.
Formula: (MO call)
Avg of (Timer(180Ringing)) – (Timer (SIP INVITE Request))
3. MHT/ACD: Average Call Duration (s)
1. It is the average call length in the network.
Category Of KPI: VoLTE service Integrity and Retainability
Source: TAS.
Formula: (MO call)
Avg Call Duration: (Timer(BYE)) – (Timer (200 OK for SIP INVITE Request))
4. RSR: Registration Success Ratio (%)
1. This KPI will tell if the customer is successfully registered to IMS Network.
2. It is calculated on the number of users successfully completed SIP Registration.
3. Good range is 99% +. If there is a reduction, then we can see that the customers are not able to register to the network.
Category Of KPI: Accessibility
Formula:
(Count of (200 OK) for Registration Completed)/ (Count of SIP REGISTER sent from UE excluding 401 Error Attempts) * 100%
Source: PCSCF.
Let us see in details VoLTE User Plane Performance KPI’s
1. Mute Rate (%)
2. MOS Score (1-5)
3. RTP Packet Loss (%)
4. One Way Calls. (%)
1. Mute Rate (%)
1. It is the case, where the calls are getting mute in both the direction.
2. Good range is <1%
Category Of KPI: VoLTE service Integrity (Voice Quality)
Source: Packet Capture.
Formula:
Avg Call Duration: % of calls Muted
2. MOS Score (1-5): Mean Opinion Score
1. Good range is >3.5%
2. It is the measure of voice quality
Category Of KPI: VoLTE service Integrity (Voice Quality)
3. RTP Packet Loss (%)
1. Good range is <1 % Loss
Category Of KPI: VoLTE service Integrity (Voice Quality)
Source: Packet Capture or SBC.
Formula:
% of RTP Packets lost in uplink or down link direction.
4. One Way Calls. (%)
1. Good range is <1 % of total calls.
Category Of KPI: VoLTE service Integrity (Voice Quality)
Source: Packet Capture or SBC.
Formula:
% of calls having no voice packets count for 2 or 5 sec in either upstream or down stream.
Reference 3GPP 32.454, 32.409