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TR 28.826
Study on Nchf charging services Phase 2 improvements and optimizations

V18.0.0 (Wzip)2023/12  62 p.
Mr. Törnkvist, Robert
Ericsson LM

full Table of Contents for  TR 28.826  Word version:  18.0.0

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1  Scopep. 8

The present document studies the potential use cases, requirements, and solutions for the enhancements of the Nchf converge charging service.
The study will cover and identify gaps for:
  • optimizations regarding amount of information in the request and number of requests;
  • enhancement of input to rating;
  • cancelling of chargeable events for unsuccessful scenarios;
  • enhancement of non-blocking mechanism;
  • enhancements of triggers having more consistent triggers and use of NF specific triggers.
Improvements on how to maintain the source code presentations (yaml and ASN.1) the document structure for these will be studied,

2  Referencesp. 8

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
TR 21.905: "Vocabulary for 3GPP Specifications".
TS 32.255: "5G data connectivity domain charging; stage 2".
TS 23.503: "Policy and charging control framework for the 5G System (5GS); Stage 2".
TS 29.500: "5G System; Technical Realization of Service Based Architecture; Stage 3".
TS 32.240: "Telecommunication management; Charging management; Charging architecture and principles".
TS 32.291: "Telecommunication management; Charging management; 5G system; Charging service, stage 3".
TS 32.298: "Telecommunication management; Charging management; Charging Data Record (CDR) parameter description".
TS 32.299: "Telecommunication management; Charging management; Diameter charging application".
TS 23.501: "3GPP TS 23.501:"System Architecture for the 5G System".
TS 23.203: "Policy and charging control architecture".
TS 29.594: "5G System; Spending Limit Control Service; Stage 3".
TS 32.290: "Telecommunication management; Charging management; 5G system; Services, operations and procedures of charging using Service Based Interface (SBI)".
RFC 4006  (2005): "Diameter Credit-Control Application".
RFC 8506  (2019): "Diameter Credit-Control Application".
TS 29.513: "5G System; Policy and Charging Control signalling flows and QoS parameter mapping; Stage 3".
TS 29.594: "5G System; Spending Limit Control Service; Stage 3".
TS 32.254: "Telecommunication management; Charging management; Exposure function Northbound Application Program Interfaces (APIs) charging".
TS 32.256: "Telecommunication management; Charging management; 5G Data connectivity domain charging; stage 2".
TS 29.244: "Technical Specification Group Core Network and Terminals; Interface between the Control Plane and the User Plane Nodes; Stage 3".
TS 29.591: "5G System; Network Exposure Function Southbound Services; Stage 3".
TS 29.541: "5G System; Network Exposure (NE) function services for Non-IP Data Delivery (NIDD) and Short Message Services (SMS); Stage 3".
TS 29.542: "5G System; Session management services for Non-IP Data Delivery (NIDD); Stage 3".
TS 38.300: "NR; NR and NG-RAN Overall description; Stage-2".
TS 32.251: "Telecommunication management; Charging management; Packet Switched (PS) domain charging".

3  Definitions of terms, symbols and abbreviationsp. 9

3.1  Termsp. 9

For the purposes of the present document, the terms given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

3.2  Symbolsp. 9


3.3  Abbreviationsp. 9

For the purposes of the present document, the abbreviations given in 3GP TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.

4  Overviewp. 9

The Nchf converged charging services was first released in Rel-15. This first iteration was to a large extent, with some minor exceptions, copying and combining its predecessors, Ro and Rf, based on Diameter to a Service Based Interface (SBI) supporting converged charging service. The depiction of the internal architecture of the Converged Charging System (CCS) was to a large extent based on the Online Charging System (OCS).
The combination of the Diameter Ro and Rf interfaces into one converged charging service together with the move of the integration point for CDRs have led to that all the information previously reported and transported over two or more interfaces now needs to be transported over a single interface. This makes it essential that the converged charging interface is optimized in regard to the amount of information and number of reports sent, or at least allows for such an optimization if needed.
The information that may be used to assist the determine of reservation in the CCS is not defined except for the rating group. This means that for an immediate event or in an initial request the information about the event or session is limited and lacks accuracy.
Low latency requirements increased by new business cases may need enhancements to the non-blocking mechanism.
Charging of new service together with converged charging have increased the need for more information in the input to rating.
The use of event-based charging has led to a need for cancelling the charging for the chargeable event, e.g. refund, for unsuccessful scenarios or cases not possible to fulfil.
The document structure of the actual service, i.e. yaml, followed the handling of Ro and Rf, based on Diameter, which may need improvements.

5  Charging scenarios and key issuesp. 10

5.1  Charging information optimizationp. 10

5.1.1  Generalp. 10

5.1.2  Use casesp. 10

5.1.3  Potential charging requirementsp. 12

5.1.4  Key issuesp. 12

5.1.5  Solutionsp. 13  Solution #1.1: New immediate trigger variantp. 13  Solution #1.2: Keep rating group information togetherp. 16  Solution #1.3: NF consumer ensuring accuracy of locationp. 16  Solution #1.4: Stop and discard the used units during re-authorizationp. 16  Solution #1.5: Stop and report the used units during re-authorizationp. 16  Solution #1.6: CHF control of granted quota during re-authorizationp. 17  Solution #1.7: Continue and report the used units during re-authorizationp. 17  Solution #1.8: CHF control of ChargingInformationData sizep. 17  Solution #1.9: CHF control of chargingdata sizep. 18  Solution #1.10: Bitrate Charging supported by SMFp. 19  Solution #1.11 New attribute on all levels of the CDR structurep. 20  Solution #1.12 New attribute in the ChargingRecord, using sequence number for multiple attributesp. 21  Solution #1.13 New attribute in the ChargingRecord, using hash value for multiple attributesp. 22  Solution #1.14: NF consumer reporting accuracy of locationp. 23  Solution #1.15: IoT Charging information Optimizationp. 24  Solution #1.16: Without addition of undefined CDR parametersp. 25  Solution #1.17: Vendor special for undefined CDR parametersp. 25  Solution #1.18: Introduce a container referencep. 25  Solution #1.19: IoT NEF charging information optimizationp. 26  Solution #1.20: Reserve a range of special numbers for undefined valuesp. 28  Solution #1.21: Bitrate charging supported by CHFp. 28  Solution #1.22: Bitrate charging using volume and time measurementp. 30

5.1.6  Evaluationp. 31

5.1.7  Conclusionsp. 32

5.2  Charging request optimizationp. 32

5.3  Rating input enhancementp. 36

5.4  Chargeable events and sessions cancellingp. 42

5.5  Non-blocking mechanism enhancementp. 45

6  Documentation improvementsp. 51

7  Conclusions and recommendationsp. 59

$  Change historyp. 60

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