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UE-initiated PLR Measurement Procedure in PMFP Procedure


Author: Samuel Lin
Date: 2024/01/03


Performance measurement function protocol (PMFP) procedures are performed between a performance measurement function (PMF) in a UE and a PMF in the UPF.

The PMF can measure Round-Trip Time (RTT) and Packet Loss Rate (PLR) by exchanging information through PMFP messages to perform these calculations.

In this document, we solely introduce the UE-initiated Packet Loss Rate (PLR) Measurement Procedure.



Counting start:

  • [1-4] UE initiates measurement by sending a PMFP PLR Count Request message to the UPF. UE and UPF commence respective packet counting processes.

Reporting and Potential Restart:

  • [5, 6-2] UE sends a PMFP PLR Report Request message to request UPF's counted packets and may optionally request counting restart.
  • [7-2, 8] UPF responds with a PMFP PLR Report Response message containing counted packets and potentially restarts counting if requested and accepted.

PLR Calculation and Procedure Termination:

  • [6-1, 7-1] Procedure terminates if restart is not requested or not accepted.
  • [9] UE calculates the UL PLR (Uplink PLR) based on local and reported packet counts.
  • [10-14] Counting can be restarted multiple times upon mutual agreement between UE and UPF, enabling continuous measurement.

Key Considerations

Message Transport: All PMFP messages are transported over the same QoS flow on the same access.

PLR Calculation: UE derives the UL PLR using its own transmitted packet count and the UPF's reported received packet count.

Compliance: The procedure adheres to 3GPP specifications for packet loss management.

Additional Notes

QoS Flow Selection: The specific QoS flow for message transmission is contingent upon the measurement type (default or non-default QoS rule).

Continuous Measurement: The restart capability facilitates ongoing packet loss monitoring.


This UE-initiated PLR measurement procedure provides a standardized and coordinated approach to assess UL packet loss within 5G networks. Its adherence to 3GPP specifications ensures interoperability and consistency across network implementations.


The network-initiated PLR measurement procedure is to enable UPF to measure the PLR of DL traffic access to the UE through the MA PDU session. The process is the same as the UE-initiated PLR measurement, except that the objects are reversed.


  • 3GPP TS 24.193: 5G System; Access Traffic Steering, Switching and Splitting (ATSSS); Stage 3
  • 3GPP TS 23.501: System architecture for the 5G System (5GS)


Hello, I am Samuel Lin. I have just started making contributions to the free5GC core network. This post is my first blog, so if there are any inquiries or identification of errors within, we welcome discussion and correction. Your feedback is invaluable, so please don't hesitate to reach out via email to share your insights.

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Additionally, I have provided the graph with the network-initiated PLR measurement procedure.



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