WO2025066509A1

WO2025066509A1 - Method and apparatus for charging

Info

Publication number: WO2025066509A1
Application number: PCT/CN2024/108095
Authority: WO
Inventors: Zhansheng WEI; Jiehong YANG; Robert TÖERNKVIST; Chunmiao LIU
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-09-28
Filing date: 2024-07-29
Publication date: 2025-04-03
Anticipated expiration: 2026-03-28

Abstract

Embodiments of the present disclosure provide method and apparatus for charging. A method performed by a first network node implementing a session management function (SMF) may comprise sending, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging. The initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. The method may further comprise sending, during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

Description

METHOD AND APPARATUS FOR CHARGING

PRIORITY CLAIM

This present application claims priority from PCT international application No. PCT/CN2023/122627, filed on September 28, 2023, the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The non-limiting and exemplary embodiments of the present disclosure generally relate to the technical field of communications, and specifically to methods and apparatuses for charging.

BACKGROUND

This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

In various communication networks such as fifth generation system (5GS) as defined by 3rd Generation Partnership Project (3GPP) , there is provided a network node that implements charging. For example, in 5GS, the charging may be performed by the Session Management Function (SMF) interacting with Charging Function (CHF) using a service-based interface Nchf specified in 3GPP Technical Specification (TS) 32.290 V18.3.0 and 3GPP TS 32.291 V18.2.0, the disclosures of which are incorporated by reference herein in their entirety.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

There may be some problems for existing charging procedures.

During a charging procedure, the network node that implements charging and/or the network node that implements session management may be inserted, changed or removed due to various reasons e.g. user equipment (UE) 's mobility.

For example, for home routed roaming protocol data unit (PDU) session, during a mobility procedure, a visited SMF (V-SMF) may change. According to clauses 5.2.2.14.9 and 5.2.2.14.10 of 3GPP TS 32.255 V18.0.1, the disclosure of which is incorporated by reference herein in its entirety, when a V-SMF is changed, the charging session between the old V-SMF and old visited (V-CHF) is released, and a new charging session is established between the new V-SMF and new V-CHF.

From an old V-CHF’s point of view, it can’t distinguish whether it’s a PDU session release procedure or a mobility procedure with V-SMF removal when receives a Charging Data Request [Terminate] message.

From a new V-CHF’s point of view, it can’t distinguish whether it’s a PDU session establishment procedure or a mobility procedure with V-SMF insertion when receives a Charging Data Request [Initial] message.

In a live network, when the V-SMF is changed, no matter whether the new V-CHF and the old V-CHF are the same or not, a post-processing system is not able to put together the true history of the PDU session based on received charging records from V-SMFs.

CHF Charging Data Records (CDRs) for the same user’s PDU session may be dispersed in different V-CHFs and there is no explicit indication that these CDRs are generated for the same user’s PDU session e.g. because of UE’s mobility. In a home CHF (H-CHF) , the CDRs may be generated for the same user’s PDU session with mobility event triggers. So it's not convenient to do the charging coordination between the operation in Visited Public Land Mobile Network (V-PLMN or VPLMN) and Home Public Land Mobile Network (H-PLMN or HPLMN) based on the event triggers causing CDR closure. For example, when the CDRs are for statistical purposes, it is counted as create and release in V-CHF but it's counted as mobility in H-CHF.

To overcome or mitigate at least one above mentioned problems or other problems, an improved solution for charging may be desirable.

In a first aspect of the disclosure, there is provided a method performed by a first network node implementing a session management function (SMF) . The method may comprise sending, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging. The initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. The method may further comprise sending, during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

In a second aspect of the disclosure, there is provided method performed by a second network node implementing charging. The method may comprise receiving, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request from a first network node implementing a session management function (SMF) . The initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. The method may further comprise receiving, during a mobility procedure of a terminal device with visited SMF change, a termination data request from a first network node implementing a SMF. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

In a third aspect of the disclosure, there is provided a first network node implementing a session management function (SMF) . The first network node comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said first network node is operative to send, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging. The initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. Said first network node is further operative to send, during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

In a fourth aspect of the disclosure, there is provided a second network node implementing charging. The second network node comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said second network node is operative to receive, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request from a first network node implementing a session management function (SMF) . The initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. Said second network node is further operative to receive, during a mobility procedure of a terminal device with visited SMF change, a termination data request from a first network node implementing a SMF. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

In a fifth aspect of the disclosure, there is provided a computer program comprising instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of the first or second aspect.

In a sixth aspect of the disclosure, there is provided a computer-readable storage medium storing instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of the first or second aspect.

Embodiments herein may provide many advantages, of which a non-exhaustive list of examples follows. In some embodiments herein, when a terminal device moves to a new network node implementing session management e.g. because of mobility, the operator can identify it’s not a new attach but a mobility procedure from other radio access technology (RAT) types/Access Type or from an old network node implementing session management. In some embodiments herein, when a terminal device leaves from an old network node implementing session management because of mobility, the operator can identify it’s not a PDU session release but a mobility procedure to other RAT type/Access Type or to a new network node implementing session management. In some embodiments herein, for inter-operator charging settlement, the charging records from the visited network will be consistent when comparing with the charging records from the home network. The embodiments herein are not limited to the features and advantages mentioned above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent, by way of example, from the following detailed description with reference to the accompanying drawings, in which like reference numerals or letters are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and not necessarily drawn to scale, in which:

FIG. 1a shows a flowchart of Roaming Home routed PDU session inter-PLMN V-SMF change;

FIG. 1b shows a flowchart of Roaming Home routed PDU session intra-PLMN V-SMF change;

FIG. 2 schematically shows a high level architecture in a 5G network according to an embodiment of the present disclosure;

FIG. 3 schematically shows a reference architecture for the Nchf interface;

FIGs. 4-6 show flowcharts of methods according to embodiments of the present disclosure;

FIG. 7 shows a flowchart of 5GS to EPS handover using N26 interface with V-SMF removal according to another embodiment of the present disclosure; and

FIGs. 8a, 8b and 8c are block diagrams showing an apparatus, a first network node and a second network node according to embodiments of the disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

As used herein, the term “network” refers to a network following any suitable communication standards such as new radio (NR) , long term evolution (LTE) , LTE-Advanced, wideband code division multiple access (WCDMA) , high-speed packet access (HSPA) , Code Division Multiple Access (CDMA) , Time Division Multiple Address (TDMA) , Frequency Division Multiple Access (FDMA) , Orthogonal Frequency-Division Multiple Access (OFDMA) , Single carrier frequency division multiple access (SC-FDMA) and other wireless networks. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , etc. UTRA includes WCDMA and other variants of CDMA. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, Ad-hoc network, wireless sensor network, etc. In the following description, the terms “network” and “system” can be used interchangeably. Furthermore, the communications between two devices in the network may be performed according to any suitable communication protocols, including, but not limited to, the communication protocols as defined by a standard organization such as Third Generation Partnership Project (3GPP) . For example, the communication protocols may comprise the first generation (1G) , 2G, 3G, 4G, 4.5G, 5G, 6G communication protocols, and/or any other protocols either currently known or to be developed in the future.

The term “network device” or “network node” or “network function” refers to any suitable function which can be implemented in a network entity (physical or virtual) of a communication network. For example, the network function can be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g. on a cloud infrastructure. For example, the 5G system (5GS) may comprise a plurality of NFs such as Access and Mobility Management Function (AMF) , Session Management Function (SMF) , Authentication Service Function (AUSF) , Unified Data Management (UDM) , Policy Control Function (PCF) , Application Function (AF) , Network Exposure Function (NEF) , User plane Function (UPF) and Network Repository Function (NRF) , radio access network (RAN) , service communication proxy (SCP) , network data analytics function (NWDAF) , Network Slice Selection Function (NSSF) , Network Slice-Specific Authentication and Authorization Function (NSSAAF) , etc. For example, the 4G system (such as Long Term Evolution (LTE) ) may include Mobile Management Entity (MME) , home subscriber server (HSS) , PCRF (Policy and Charging Rules Function) , PGW (Packet Data Network Gateway) , PGW control plane (PGW-C) , Serving gateway (SGW) , SGW control plane (SGW-C) , E-UTRAN Node B (eNB) , etc. In other embodiments, the network function may comprise different types of NFs for example depending on a specific network.

Virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to a provider edge node and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components (e.g., via one or more applications, components, functions, virtual machines or containers executing on one or more physical processing nodes in one or more networks) .

In some embodiments, some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines implemented in one or more virtual environments hosted by one or more of hardware nodes. Further, in embodiments in which the virtual node is not a radio access node or does not require radio connectivity (e.g., a core network node) , then the virtual node may be entirely virtualized.

The functions may be implemented by one or more applications (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc. ) operative to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein. Applications are run in virtualization environment which provides hardware comprising processing circuitry and memory. Memory contains instructions executable by processing circuitry whereby application is operative to provide one or more of the features, benefits, and/or functions disclosed herein.

Virtualization environment, comprises general-purpose or special-purpose network hardware devices comprising a set of one or more processors or processing circuitry, which may be commercial off-the-shelf (COTS) processors, dedicated Application Specific Integrated Circuits (ASICs) , or any other type of processing circuitry including digital or analog hardware components or special purpose processors. Each hardware device may comprise memory which may be non-persistent memory for temporarily storing instructions or software executed by processing circuitry. Each hardware device may comprise one or more network interface controllers (NICs) , also known as network interface cards, which include physical network interface. Each hardware device may also include non-transitory, persistent, machine-readable storage media -having stored therein software and/or instructions executable by processing circuitry. Software may include any type of software including software for instantiating one or more virtualization layers (also referred to as hypervisors) , software to execute virtual machines as well as software allowing it to execute functions, features and/or benefits described in relation with some embodiments described herein.

Virtual machines, comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer or hypervisor. Different embodiments of the instance of virtual appliance may be implemented on one or more of virtual machines, and the implementations may be made in different ways.

During operation, processing circuitry executes software to instantiate the hypervisor or virtualization layer, which may sometimes be referred to as a virtual machine monitor (VMM) . Virtualization layer may present a virtual operating platform that appears like networking hardware to virtual machine.

The term “terminal device” refers to any end device that can access a communication network and receive services therefrom. By way of example and not limitation, the terminal device refers to a mobile terminal, user equipment (UE) , or other suitable devices. The UE may be, for example, a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a portable computer, an image capture terminal device such as a digital camera, a gaming terminal device, a music storage and a playback appliance, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet, a wearable device, a personal digital assistant (PDA) , a portable computer, a desktop computer, a wearable terminal device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE) , a laptop-mounted equipment (LME) , a USB dongle, a smart device, a wireless customer-premises equipment (CPE) and the like. In the following description, the terms “terminal device” , “terminal” , “user equipment” and “UE” may be used interchangeably. As one example, a terminal device may represent a UE configured for communication in accordance with one or more communication standards promulgated by the 3GPP (3rd Generation Partnership Project) , such as 3GPP LTE standard or NR standard. As used herein, a “user equipment” or “UE” may not necessarily have a “user” in the sense of a human user who owns and/or operates the relevant device. In some embodiments, a terminal device may be configured to transmit and/or receive information without direct human interaction. For instance, a terminal device may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the communication network. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but that may not initially be associated with a specific human user.

As yet another example, in an Internet of Things (IoT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed terms.

As used herein unless expressly stated to the contrary, the phrase “at least one of A and B” or “at least one of A or B” should be understood to mean any of the following “only A, only B, or both A and B. ” The phrase “A and/or B” should be understood to mean any of the following “only A, only B, or both A and B” .

As used herein unless expressly stated to the contrary, the phrase “aplurality of” followed by a conjunctive list of enumerated items (e.g., “A and B” , “A, B, and C” ) is intended to mean “multiple items, with each item selected from the list consisting of” the enumerated items. For example, “aplurality of A and B” is intended to mean any of the following: more than one A; more than one B; or at least one A and at least one B.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

It is noted that these terms as used in this document are used only for ease of description and differentiation among nodes, devices or networks etc. With the development of the technology, other terms with the similar/same meanings may also be used.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

FIG. 1a shows a flowchart of Roaming Home routed PDU session inter-PLMN (Public Land Mobile Network) V-SMF change, which is same as Figure 5.2.2.12.6.1 of 3GPP TS 32.255 V18.0.1.

Clause 5.2.2.12.6 of 3GPP TS 32.255 V18.0.1 describes the steps as following.

Step 0ch-a. Ongoing charging session in the old VPLMN for UE served by the old V-SMF, using “Charging Identifier 1” .

Step 0ch-b. Ongoing charging session for HPLMN for UE served by the old V-SMF, using “Charging Identifier 1” .

Steps 1-2. UE moves into a different PLMN, and the new AMF determines the new V-SMF based on service area.

Steps 3-4b. SM Context retrieval by the new V-SMF from the old V-SMF. The “Charging Identifier 1” is conveyed to the new V-SMF.

Step 4ch-a. The UE is identified as a roamer, the CHF is selected accordingly.

Step 4ch-b. A Charging Data Request [Initial] is sent to the new V-CHF, indicating “in-bound roamer” and “Charging Identifier 1” received on step 4b.

Step 4ch-c. The new V-CHF may open a CDR (indicating “in-bound roamer” ) .

Step 4ch-d. The new V-CHF acknowledges by sending Charging Data Response [Initial] to new V-SMF and optionally supplies a “Roaming charging profile” to new V-SMF which overrides the default one.

Step 5-7c. Refer steps 5 to 7c in Figure 4.23.4.3-1 of 3GPP TS 23.502 V18.1.1.

Step 7ch-a. A Charging Data Request [Termination] is sent to old V-CHF, with “Charging Identifier 1” .

Step 7ch-c. The old V-CHF closes the CDR.

Step 7ch-d. The old V-CHF acknowledges by sending Charging Data Response [Initial] to old V-SMF.

Step 8a. Nsmf_PDUSession_Update Request from new V-SMF towards the H-SMF with the “Roaming Charging Profile” .

Step 8ach-a. A Charging Data Request [Update] is sent to H-CHF in HPLMN, indicating the V-SMF change and “Roaming charging profile” if received from the VPLMN. This step occurs before SMF interacts with the UPF.

Step 8ach-b. The H-CHF in HPLMN updates the CDR.

Step 8ach-c. The H-CHF in HPLMN acknowledges by sending Charging Data Response [Update] to the H-SMF and optionally supplies the HPLMN selected “Roaming Charging Profile” for this VPLMN.

Step 8c. Nsmf_PDUSession_Update Response from H-SMF to new V-SMF with the “Roaming charging profile” .

Step 8cch-a. A Charging Data Request [Update] is sent to V-CHF with charging information received from H-SMF, which includes the HPLMN selected “Roaming charging profile” if received.

Step 8cch-b. The V-CHF updates the CDR.

Step 8cch-c. The V-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

Steps 9, 17-21. Refer steps 9 and 17 to 21 in Figure 4.23.4.3-1 of 3GPP TS 23.502 V18.1.1.

FIG. 1b shows a flowchart of Roaming Home routed PDU session intra-PLMN V-SMF change, which is same as Figure 5.2.2.12.7.1 of 3GPP TS 32.255 V18.0.1.

Clause 5.2.2.12.7 of 3GPP TS 32.255 V18.0.1 describes the steps as following.

Steps 0ch-aand 0ch-b. Same as in Figure 5.2.2.12.6.1 of 3GPP TS 32.255 V18.0.1.

Steps 1-2. UE moves out of the old V-SMF service area, and the new AMF determines the new V-SMF service area in the same VPLMN.

Steps 3-4b. SM Context retrieval by new V-SMF from the old V-SMF. The "Charging Identifier 1" , the "Home roaming charging profile" , and the V-CHF address, are conveyed to the new V-SMF.

Step 4ch-a. A Charging Data Request [Initial] is sent to V-CHF, indicating "in-bound roamer" and "Charging Identifier 1" received on step 4b.

NOTE: Since the same V-CHF is used, the "Home roaming charging profile" to be used is already known by the V-CHF

Step 4ch-b. The V-CHF may open a CDR (indicating “in-bound roamer” ) .

Step 4ch-c. The V-CHF acknowledges by sending Charging Data Response [Initial] to new V-SMF.

Step 4ch-d. A Charging Data Request [Termination] is sent to V-CHF, with “Charging Identifier 1” .

Step 4ch-e. The V-CHF closes the CDR.

Step 4ch-f. The V-CHF acknowledges by sending Charging Data Response [Termination] to old V-SMF.

Steps 5-21. Same steps as in Figure 5.2.2.12.6.1 of 3GPP TS 32.255 V18.0.1, except the "Roaming charging profile" is not renegotiated, i.e., not contained in steps 8a, 8ach-a, 8ach-c, 8c and 8cch-a. clause 5.2.2.12.8 of 3GPP TS 32.255 V18.0.1 Inter-PLMN V-SMF insertion -without Charging Identifier string

The flow is the same as in clause 5.2.2.12.5 of 3GPP TS 32.255 V18.0.1, with the difference in steps:

Steps 3-4b. SM Context retrieval by V-SMF from the H-SMF. The "Charging Identifier 1" is converted from a string to an integer and conveyed to the V-SMF. The conversion needs to be done so that the new Charging Identifier is unique within the V-SMF.

Step 4ch-b. A Charging Data Request [Initial] is sent to the V-CHF, indicating "in-bound roamer" and "Charging Identifier 1" as integer received on step 4b.

Step 8ach-a. A Charging Data Request [Update] is sent to H-CHF in HPLMN (e.g. based on PLMN change trigger) , indicating the PLMN change, "Charging Identifier 1" as integer or string, and "Roaming charging profile" if received from the VPLMN.

Although the subject matter described herein may be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a communication system complied with the exemplary system architectures illustrated in FIGs. 2-3. For simplicity, the system architectures of FIGs. 2-3 only depict some exemplary elements. In practice, a communication system may further include any additional elements suitable to support communication between terminal devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or terminal device. The communication system may provide communication and various types of services to one or more terminal devices to facilitate the terminal devices’ access to and/or use of the services provided by, or via, the communication system.

FIG. 2 schematically shows a high level architecture in a 5G network according to an embodiment of the present disclosure. The architecture of FIG. 2 may be similar to Figure 4.2.3-1 of 3GPP TS 23.501 V18.1.0, the disclosure of which is incorporated by reference herein in its entirety. The system architecture of FIG. 2 may comprise some exemplary elements such as AUSF, AMF, data network (DN) , NEF, NRF, NSSF, PCF, SMF, UDM, UPF, AF, UE, (R) AN, Service Communication Proxy (SCP) , Network Slice-Specific Authentication and Authorization Function (NSSAAF) , Network Slice Admission Control Function (NSACF) , Edge Application Server Discovery Function (EASDF) , CHF, etc.

In accordance with an exemplary embodiment, the UE can establish a signaling connection with the AMF over the reference point N1, as illustrated in FIG. 2. This signaling connection may enable NAS (Non-access stratum) signaling exchange between the UE and the core network, comprising a signaling connection between the UE and the (R) AN and the N2 connection for this UE between the (R) AN and the AMF. The (R) AN can communicate with the UPF over the reference point N3. The UE can establish a protocol data unit (PDU) session to the DN (data network, e.g. an operator network or Internet) through the UPF over the reference point N6.

As further illustrated in FIG. 2, the exemplary system architecture also contains the service-based interfaces such as Nnrf, Nnef, Nausf, Nudm, Npcf, Namf, Nnsacf, Neasdf, Nchf and Nsmf exhibited by NFs such as the NRF, the NEF, the AUSF, the UDM, the PCF, the AMF, the NSACF, the EASDF, CHF and the SMF. In addition, FIG. 2 also shows some reference points such as N1, N2, N3, N4, N6 and N9, which can support the interactions between NF services in the NFs. For example, these reference points may be realized through corresponding NF service-based interfaces and by specifying some NF service consumers and providers as well as their interactions in order to perform a particular system procedure.

FIG. 3 schematically shows a reference architecture for the Nchf interface, which is the same as Figure 4.2.1 of 3GPP TS 32.290 V18.3.0. As shown in FIG. 3, the NFs with charging trigger function (CTF) interact with CHF using Nchf interface for converged charging or offline only charging. The NF PCF interacts with CHF using Nchf interface for Spending Limit Control. The Nchf is a service based interface for NF and CHF.

FIG. 4 shows a flowchart of a method according to an embodiment of the present disclosure, which may be performed by an apparatus implemented in or at or as a first network node or communicatively coupled to the first network node. As such, the apparatus may provide means or modules or circuits for accomplishing various parts of the method 400 as well as means or modules or circuits for accomplishing other processes in conjunction with other components.

At block 402, optionally, the first network node may send, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging.

In an embodiment, the initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure.

At block 404, optionally, the first network node may send, during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging.

In an embodiment, the termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

In an embodiment, the initial charging data request may comprise first information indicating an insertion of the first network node during a mobility procedure.

In an embodiment, the initial charging data request may comprise first information indicating an insertion of a new first network node and/or an removal of an old first network node.

In an embodiment, the initial charging data request may comprise first information indicating a change of the first network node (e.g. V-SMF change) , e.g. a new first network node is inserted and an old first network node is removed.

In an embodiment, the initial charging data request may comprise first information indicating a relocation of the first network node (e.g. V-SMF Relocation) , e.g. a new first network node is inserted and an old first network node is removed.

In an embodiment, the initial charging data request may comprise first information indicating inter serving node change.

The first network node may be any suitable network node or network function or network device which can implement a session management function (SMF) . In an embodiment, the first network node may comprise a visited session management function (SMF) as described in 3GPP TS 23.501 V18.1.0. In another embodiment, the first network node may be a visited session management node in 6G network as defined by 3GPP.

In an embodiment, the first network node may be a new (inserted) visited network node. The visited network node may be a network node in a visited network.

The second network node may be any suitable network device or network node or network function which can implement charging. In an embodiment, the second network node may comprise a visited charging function (CHF) as described in 3GPP TS 23.501 V18.1.0. In another embodiment, the second network node may be a visited charging node in 6G network as defined by 3GPP.

The initial charging data request may be the first charging data request sent by the first network node. In an embodiment, the initial charging data request may be similar to the Charging Data Request [Initial] as described in 3GPP TS 32.255 V18.0.1 except that it further comprises the first information or the trigger information.

The first information may be any suitable information such as a bit, a flag, an indicator, an indication, an enumeration value, or a Boolean value, an event trigger, etc. In an embodiment, the first information may comprise an indicator or an event trigger.

In an embodiment, the indicator may be comprised in protocol data unit session information such as PDUSessionInformation as described in clause 6.1.6.2.2.8 of 3GPP TS 32.291 V18.2.0, the disclosure of which is incorporated by reference herein in its entirety.

For example, the indicator may be a ‘vSmfChange’ indicator in information element (IE) PDUSessionInformation and the first network node may include the indicator in the initial charging data request. The indicator may be used to indicate that a new first network node (e.g. V-SMF) insertion during a mobility procedure. The second network node (e.g. V-CHF) may include the indicator in the first charging data record when generating the first charging data record with the new first network node (e.g. new V-SMF) . The data type of the indicator may be Boolean.

For example, the event trigger may be ‘VSMF_CHANGE’ which may be included in the initial charging data request. The event trigger may be used to indicate that a new first network node (e.g. V-SMF) insertion during a mobility procedure. The second network node (e.g. V-CHF) may include the new trigger type together with other trigger types that cause the charging data record closure in the first charging data record when generating the first charging data record with the new first network node (e.g. new V-SMF) . In CHF, multiple event triggers can be included in a CDR record, so the CHF can include ‘VSMF_CHANGE’ together with other trigger types that trigger the CDR closure when generating the first CDR record with the first network node (e.g. new V-SMF) . The Same event trigger ‘VSMF_CHANGE’ can be also used for the last record of the old network node.

The first network node may be inserted due to various reasons such as terminal node’s mobility, load balance, energy saving, device maintenance, etc. In an embodiment, the first network node may be inserted during a mobility procedure.

The mobility procedure may be any suitable mobility procedure for example which can cause a new first network node is inserted and/or an old first network node is removed.

In an embodiment, the mobility procedure may comprise at least one of a terminal device moves from evolved packet system (EPS) to fifth generation system (5GS) with visited SMF insertion, a terminal device moves from a non Third Generation Partnership Project (3GPP) access network to 5GS with visited SMF insertion, a terminal device moves from home public land mobile network (PLMN) to visited PLMN in 5GS with visited SMF insertion, a terminal device moves from a visited PLMN to another visited PLMN with visited SMF change, or a terminal device moves in a same visited PLMN with visited SMF change. For example, the mobility procedure may be same or similar as/to the corresponding mobility procedure as described in various 3GPP specifications such as 3GPP TS 23.502 V18.1.1, 3GPP TS 32.255 V18.0.1, etc. The non-3GPP access network may comprise wireless local area network.

The first information may be used for various purposes. In an embodiment, the first information may be used by the second network node to include the first information in a first charging data record when the second network node generates the first charging data record with the first network node.

In an embodiment, when the terminal device moves to the first network node during the mobility procedure, the trigger information is used by the second network node to include the trigger information in a first charging data record when the second network node generates the first charging data record with the first network node.

In an embodiment, when the terminal device leaves from the first network node during the mobility procedure, the trigger information is used by the second network node to include the trigger information in a last charging data record when the second network node generates the last charging data record with the first network node.

In an embodiment, the first information may be used to identify session continuity. For example, when CDRs for the same user PDU session are dispersed in different V-CHFs, the first information may be used as an explicit indication that these CDRs are generated for the same user PDU session e.g. because of UE’s mobility. In H-CHF, the CDRs are generated for the same user PDU session with mobility event triggers, so it is convenient to do the charging coordination between the operation in V-PLMN and H-PLMN based on the event triggers causing CDR closure.

In an embodiment, the trigger information may be used to identify session continuity.

The charging data record may comprise a formatted collection of information about a chargeable event (e.g. time of call set-up, duration of the call, amount of data transferred, the first network node change (e.g. V-SMF change) , etc. ) for use in billing and accounting. For each party to be charged for parts of or all charges of a chargeable event, a separate charging data record may be generated, i.e. more than one charging data record may be generated for a single chargeable event, e.g. because of its long duration, or because more than one charged party is to be charged. In an embodiment, the charging data record may be similar to the charging data record (CDR) as described in various 3GPP specifications such as 3GPP TS 23.502 V18.1.1, 3GPP TS 32.255 V18.0.1.

In an embodiment, a termination charging data request may be sent to a third network node implementing charging. The termination charging data request may comprise second information indicating a removal of a fourth network node implementing session management during the mobility procedure.

The termination charging data request and the initial charging data request may be used in combination. The termination charging data request may indicate the termination of the charging record for the old visited network node implementing session management such as V-SMF. The initial charging data request may indicate the start of the charging record for the new visited network node implementing session management such as V-SMF.

In an embodiment, the second information may be used by the third network node to include the second information in a last charging data record when the third network node generates the last charging data record with the fourth network node. In an embodiment, the second information may comprise an event trigger. In an embodiment, the second information may be used to identify session continuity. In an embodiment, the fourth network node may comprise a visited session management function (SMF) and the third network node may comprise a visited charging function (CHF) .

In an embodiment, the second network node and the third network node may be different network nodes or a same network node.

In an embodiment, the termination charging data request may comprise second information indicating a removal of the fourth network node during a mobility procedure.

In an embodiment, the termination charging data request may comprise second information indicating an insertion of a new fourth network node and/or an removal of an old fourth network node.

In an embodiment, the termination charging data request may comprise second information indicating a change of the fourth network node (e.g. V-SMF change) , e.g. a new fourth network node is inserted and an old fourth network node is removed.

In an embodiment, the termination charging data request may comprise second information indicating a relocation of the fourth network node (e.g. V-SMF Relocation) , e.g. a new fourth network node is inserted and an old fourth network node is removed.

The fourth network node may be any suitable network node or network function or network device which can implement session management. In an embodiment, the fourth network node may comprise a visited session management function (SMF) as described in 3GPP TS 23.501 V18.1.0. In another embodiment, the fourth network node may be a visited session management node in 6G network as defined by 3GPP.

In an embodiment, the fourth network node may be an old (or removed) visited network node. The visited network node may be a network node in a visited network.

The third network node may be any suitable network device or network node or network function which can implement charging. In an embodiment, the third network node may comprise a visited charging function (CHF) as described in 3GPP TS 23.501 V18.1.0. In another embodiment, the third network node may be a visited charging node in 6G network as defined by 3GPP.

The termination charging data request may be the last charging data request sent by the fourth network node. In an embodiment, the termination charging data request may be similar to the Charging Data Request [terminate] as described in 3GPP TS 32.255 V18.0.1 except that it further comprises the second information.

The second information may be any suitable information such as a bit, a flag, an indicator, an indication, an enumeration value, or a Boolean value, etc. In an embodiment, the second information may comprise an event trigger.

For example, the event trigger may be ‘VSMF_CHANGE’ which may be included in the termination charging data request. The event trigger may be used to indicate that an old (or used) network node (e.g. V-SMF) is removed during a mobility procedure. The third network node (e.g. V-CHF) may include the new trigger type in the last charging data record when generating the last charging data record with the old fourth network node (e.g. old V-SMF) .

The fourth network node may be removed due to various reasons such as terminal node’s mobility, load balance, energy saving, device maintenance, etc. In an embodiment, the fourth network node may be removed during a mobility procedure.

The mobility procedure may be any suitable mobility procedure which can cause a new first network node is inserted and/or an old fourth network node is removed.

In an embodiment, the mobility procedure may comprise at least one of a terminal device moves from fifth generation system (5GS) to evolved packet system (EPS) with visited SMF removal, a terminal device moves from 5GS to a non Third Generation Partnership Project access network with visited SMF removal, a terminal device moves from visited public land mobile network (PLMN) to home PLMN in 5GS with visited SMF removal, a terminal device moves from a visited PLMN to another visited PLMN with visited SMF change, or a terminal device moves in a same visited PLMN with visited SMF change. For example, the mobility procedure may be same or similar as/to the corresponding mobility procedure as described in various 3GPP specifications such as 3GPP TS 23.502 V18.1.1, 3GPP TS 32.255 V18.0.1, etc.

The second information may be used for various purposes. In an embodiment, the second information may be used by the third network node to include the second information in a last charging data record when the third network node generates the last charging data record with the fourth network node.

In an embodiment, the second information may be used to identify session continuity. For example, when CDRs for the same user PDU session are dispersed in different V-CHFs, the second information may be used as an explicit indication that these CDRs are generated for the same user PDU session e.g. because of UE’s mobility. In H-CHF, the CDRs are generated for the same user PDU session with mobility event triggers, so it is convenient to do the charging coordination between the operation in V-PLMN and H-PLMN based on the event triggers causing CDR closure.

In an embodiment, an initial charging data request may be sent to a second network node implementing charging. The initial charging data request comprises first information indicating an insertion of a first network node during the mobility procedure.

In an embodiment, the first network node may comprise a visited session management function (SMF) and the second network node may comprise a visited charging function (CHF) .

FIG. 5 shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in or at or as a second network node or communicatively coupled to the second network node. As such, the apparatus may provide means or modules or circuits for accomplishing various parts of the method 600 as well as means or modules or circuits for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 502, optionally, the second network node may receive, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request from a first network node implementing a session management function (SMF) .

In an embodiment, the initial charging data request comprises trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure.

At block 504, optionally, the second network node may receive, during a mobility procedure of a terminal device with visited SMF change, a termination data request from a first network node implementing a SMF.

In an embodiment, the termination charging data request comprises trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

FIG. 6 shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in or at or as a second network node or communicatively coupled to the second network node. As such, the apparatus may provide means or modules or circuits for accomplishing various parts of the method 600 as well as means or modules or circuits for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 602, optionally, when the terminal device moves to the first network node during the mobility procedure, the second network node may include the trigger information in a first charging data record when the second network node generates the first charging data record with the first network node.

At block 604, optionally, when the terminal device leaves from the first network node during the mobility procedure, the second network node may include the trigger information in a last charging data record when the second network node generates the last charging data record with the first network node.

In an embodiment, V-SMF may indicate V-CHF whether it’s a PDU Session Establishment/Release procedure or a mobility with V-SMF insertion/removal procedure.

In an embodiment, for V-SMF insertion scenarios, the new V-SMF may include a new indicator in charging data request [initial] to indicate it’s a mobility procedure with V-SMF insertion.

In an embodiment, for V-SMF removal scenarios, the old V-SMF may include a new indicator in charging data request [terminate] to indicate it’s a mobility procedure with V-SMF removal.

In an embodiment, the V-SMF insertion/removal may happen during at least one of the following procedures:

UE moves between EPS/wireless local area network (WLAN) and 5GS with V-SMF insertion,

UE moves from H-PLMN to V-PLMN in 5GS with V-SMF insertion,

UE moves from V-PLMN to H-PLMN in 5GS with V-SMF removal, or

UE moves intra/inter V-PLMN intra 5GS with V-SMF insertion and removal.

In an embodiment, the CHF may generate CDRs including the new attribute or new even trigger received from V-SMF. The post-processing system can identify the session continuity based on the new attribute or event trigger of the CHF-CDRs.

In an embodiment, it is provided proposal 1 as bellow.

It can add an indicator such as ‘vSmfChange’ in IE PDUSessionInformation and include it in charging data request [initial] . It may be used to indicate that a new V-SMF insertion during mobility procedure. The V-CHF may include this new attribute when generating the first charging data record with the new V-SMF.

In an embodiment, the indicator such as ‘vSmfChange’ may be added in PDUSessionInformation of Table 6.1.6.2.2.8-1 of 3GPP TS 32.291 V18.2.0.

Table 6.1.6.2.2.8-1: Definition of type PDUSessionInformation

In an embodiment, it may introduce a new event trigger such as ‘VSMF_CHANGE’ and include it in the charging data request [terminate] request. The V-CHF may include this new trigger type in the last charging data record with the old V-SMF.

In an embodiment, the new event trigger such as ‘VSMF_CHANGE’ may be added in Enumeration TriggerType of Table 6.1.6.3.6-1 of 3GPP TS 32.291 V18.2.0.

Table 6.1.6.3.6-1: Enumeration TriggerType

In an embodiment, it is provided proposal 2 as bellow.

It can use only one attribute (e.g. new value of TriggerType ‘VSMF_CHANGE’ ) to identify session continuity.

In an embodiment, it can include an event trigger such as ‘VSMF_CHANGE’ in charging data request [initial] . It may be used to indicate that a new V-SMF insertion during mobility procedure. The V-CHF may include this new trigger type together with other trigger types that cause the charging data record closure when generating the first charging data record with the new V-SMF because CHF-CDR supports including multiple event triggers in a CDR records.

In an embodiment, it can include the event trigger such as ‘VSMF_CHANGE’ in charging data request [terminate] . It may be used to indicate that a used V-SMF removal during mobility procedure. The V-CHF may include this new trigger type when generating the last charging data recode with the old V-SMF.

Table 6.1.6.3.6-1: Enumeration TriggerType

In an embodiment, the new attribute of proposal 1 or 2 can be applied to the Charging Data Request message between new/old V-SMF and new/old V-CHF.

FIG. 7 shows a flowchart of 5GS to EPS handover using N26 interface with V-SMF removal according to another embodiment of the present disclosure.

Step 1. The UE performs the PDU Session Setup procedure with EPS Bearer Identity (EBI) in the 5GS.

Step 2. The NG-RAN may send the Handover Required message to the AMF.

Step 3. The AMF may send the Nsmf_PDUSession_RetrieveSMContext Request message to the V-SMF.

Step 4. The V-SMF may respond with the Nsmf_PDUSession_RetrieveSMContext Response message to the AMF.

Step 5. The AMF may send the Relocation Request message to the MME.

Step 6. The MME may send the Create Session Request message to the SGW-C.

Step 7. The SGW-C may send the Session Establishment Request to the AMF.

Step 8. The SGW-U may respond with the Session Establishment Response message to the SGW-C.

Step 9. The SGW-C may respond with the Create Session Response message to the MME.

Step 10. The MME may send the Handover Request message to the E-UTRAN.

Step 11. The E-UTRAN may respond with the Handover Request Acknowledge message to the MME.

Step 12. The MME may send the Relocation Response message to the AMF.

Step 13. The AMF may send the Handover Command message to the NG-RAN.

Step 14. The NG-RAN may send the Handover Command message to the UE.

Step 15. The UE may send the Handover Complete message to the NG-RAN.

Step 16. The E-UTRAN may send the Handover Notify message to the MME.

Step 17. The MME may send the Relocation Complete Notification message to the AMF.

Step 18. The AMF may respond with the Relocation Complete Acknowledge message to the MME.

Step 19. The AMF may send the Nsmf_PDUSession_ReleaseSMContext Request message to the V-SMF.

Step 20. The V-SMF selects a V-UPF and may send the PFCP Session Release Request message to the V-UPF.

Step 21. The V-UPF may respond with the PFCP Session Release Response message to the V-SMF. The message can include termination usage reports.

Step 22. The V-SMF may send the Charging Data Request [Terminate] message to the V-CHF with volume usage and the trigger set to FINAL. The old V-SMF can indicate V-CHF that it’s the last record in the old V-SMF after inter serving node change e.g. by VSMF_CHANGE trigger. For example, the Charging Data Request [Termination] may comprise the second information e.g. indicating a removal of the old V-SMF during the mobility procedure.

Step 23. The V-CHF may respond with the Charging Data Response (Terminate) message to the V-SMF.

Step 24. The V-SMF may respond with the Nsmf_PDUSession_ReleaseSMContext Response message to the AMF.

Step 25. The MME may send the Modify Bearer Request message to the SGW-C.

Step 26. The SGW-C may send the Modify Bearer Request message to the H-SMF.

Step 27. The H-SMF may send the Npcf_SMPolicyControl_Update_Request message to the H-PCF.

Step 28. The H-PCF may respond with

the Npcf_SMPolicyControl_Update_Response message to the H-SMF.

Step 29. The H-SMF may send the PFCP Session Modification Request message to the H-UPF.

Step 30. The H-UPF may respond with the PFCP Session Modification Response message to the H-SMF.

Step 31. The H-SMF may respond with the Modify Bearer Response message to the SGW-C.

Step 32. The H-SMF may send the Charging Data Request (Update) message to the H-CHF.

Step 33. The H-CHF may respond with the Charging Data Response (Update) message to the H-SMF.

Step 34. The H-SMF may send the PFCP Session Modification Request message to the H-UPF.

Step 35. The H-UPF may respond with the PFCP Session Modification Response message to the H-SMF.

Step 36. The SGW-C may send the Sx Session Modification Request message to the SGW-U.

Step 37. The SGW-U may respond with the Sx Session Modification Response message to the SGW-C.

Step 38. The SGW-C may send the Modify Bearer Response message to the MME.

The step 22 of FIG. 7 may be enhanced according to various embodiments of the present disclosure, the other steps of FIG. 7 may be similar to the corresponding steps as described in various 3GPP specification such as 3GPP TS 32.255 V18.0.1, 3GPP TS 23.502 V18.1.1, 3GPP TS 23.401 V18.2.0, etc.

In an embodiment, handover from 5GS to evolved Packet Data Gateway (ePDG) with V-SMF removal may be same as handover from 5GS with V-SMF to EPS.

In an embodiment, for a Roaming Home routed PDU session moving from V-PLMN to H-PLMN with V-SMF removal, the old V-SMF can indicate V-CHF that it’s the last record in the old V-SMF after inter serving node change e.g. by VSMF_CHANGE trigger.

In an embodiment, for a non-roaming PDU session moving from H-PLMN to V-PLMN with V-SMF insertion, the new V-SMF can indicate V-CHF that it’s the first record in new V-SMF after inter serving node change e.g. by vSmfChange indicator or VSMF_CHANGE trigger.

In an embodiment, A. 2 Nchf_ConvergedCharging API of 3GPP TS 32.291 release 17 or 18 (e.g. 3GPP TS 32.291 V18.2.0) may add the following content.

In an embodiment, Table 5.2.1.6.1 of 3GPP TS 32.255 release 17 or 18 (e.g. 3GPP TS 32.255 V18.0.1) may add the following underlined content. QBC denotes QoS Flow Based Charging.

Table 5.2.1.6.1: Default Chargeable events in SMF for QBC

In an embodiment, Table 5.2.1.6.2 of 3GPP TS 32.255 release 17 or 18 (e.g. 3GPP TS 32.255 V18.0.1) may add the following underlined content.

Table 5.2.1.6.2: Chargeable events and their related actions in SMF for QBC

In an embodiment, Table 6.2.1.2.1 of 3GPP TS 32.255 release 17 or 18 (e.g. 3GPP TS 32.255 V18.0.1) may add the following underlined content.

Table 6.2.1.2.1: Structure of PDU Session Charging Information

In an embodiment, CHF CDRs of 3GPP TS 32.298 release 17 or 18 (e.g. 3GPP TS 32.298 V18.2.0) may add the following underlined content.

vsmfChangeFlag : : = BOOLEAN

FIG. 8a is a block diagram showing an apparatus suitable for practicing some embodiments of the disclosure. For example, any one of the first network node, the second network node, the third network node or the fourth network node described above may be implemented as or through the apparatus 800.

The apparatus 800 comprises at least one processor 821, such as a digital processor (DP) , and at least one memory (MEM) 822 coupled to the processor 821. The apparatus 800 may comprise a transmitter TX and receiver RX 823 coupled to the processor 821. The MEM 822 stores a program (PROG) 824. The PROG 824 may include instructions that, when executed on the associated processor 821, enable the apparatus 800 to operate in accordance with the embodiments of the present disclosure. A combination of the at least one processor 821 and the at least one MEM 822 may form processing means 825 adapted to implement various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented by computer program executable by one or more of the processor 821, software, firmware, hardware or in a combination thereof.

The MEM 822 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memories and removable memories, as non-limiting examples.

The processor 821 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples.

In an embodiment where the apparatus is implemented as or at the first network device, the memory 822 contains instructions executable by the processor 821, whereby the first network device operates according to any of the methods performed by the first network device as described above.

In an embodiment where the apparatus is implemented as or at the second network device, the memory 822 contains instructions executable by the processor 821, whereby the second network device operates according to any of the methods performed by the second network device as described above.

FIG. 8b is a block diagram showing a first network node implementing a session management function (SMF) according to another embodiment of the disclosure. As shown, the first network node 830 may comprise a first sending module 831 configured to send, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging. The initial charging data request comprises trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. The first network node 830 may comprise a second sending module 832 configured to send, during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

FIG. 8c is a block diagram showing a second network node implementing charging according to another embodiment of the disclosure. As shown, the second network node 850 may comprise a first receiving module 851 configured to receive, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request from a first network node implementing a session management function (SMF) . The initial charging data request may comprise trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure. The second network node 850 may comprise a second receiving module 852 configured to receive, during a mobility procedure of a terminal device with visited SMF change, a termination data request from a first network node implementing a SMF. The termination charging data request may comprise trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.

In an embodiment, when the terminal device moves to the first network node during the mobility procedure, the second network node 850 may comprise a first including module 853 configured to include the trigger information in a first charging data record when the second network node generates the first charging data record with the first network node.

In an embodiment, when the terminal device leaves from the first network node during the mobility procedure, the second network node 850 may comprise a first including module 854 configured to include the trigger information in a last charging data record when the second network node generates the last charging data record with the first network node.

The term unit or module may have conventional meaning in the field of electronics, electrical devices and/or electronic devices and may include, for example, electrical and/or electronic circuitry, devices, modules, processors, memories, logic solid state and/or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and/or displaying functions, and so on, as such as those that are described herein.

With function units, the first network node or the second network node may not need a fixed processor or memory, any computing resource and storage resource may be arranged from the first network node or the second network node in the communication system. The introduction of virtualization technology and network computing technology may improve the usage efficiency of the network resources and the flexibility of the network.

According to an aspect of the disclosure it is provided a computer program being tangibly stored on a computer readable storage medium and including instructions which, when executed on at least one processor, cause the at least one processor to carry out any of the methods as described above.

According to an aspect of the disclosure it is provided a computer-readable storage medium storing instructions which when executed by at least one processor, cause the at least one processor to carry out any of the methods as described above.

In addition, the present disclosure may also provide a carrier containing the computer program as mentioned above, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium. The computer readable storage medium can be, for example, an optical compact disk or an electronic memory device like a RAM (random access memory) , a ROM (read only memory) , Flash memory, magnetic tape, CD-ROM, DVD, Blue-ray disc and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may comprise separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses) , firmware (one or more apparatuses) , software (one or more modules) , or combinations thereof. For a firmware or software, implementation may be made through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Exemplary embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatuses. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the subject matter described herein, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any implementation or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular implementations. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The above described embodiments are given for describing rather than limiting the disclosure, and it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the disclosure as those skilled in the art readily understand. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The protection scope of the disclosure is defined by the accompanying claims.

In an embodiment, a change of 3GPP TS 32.255 releases 17 and 18 (such as 3GPP TS 32.255 V17.11.0, V18.0.1, V18.1.0, V17.8.0, etc. ) may be as following. The underlined descriptions are newly amended based on the mentioned current specification. The omitted parts can be referred to in the mentioned current specification.

First change

5.2.1.6 QoS flow Based Charging (QBC)

The omitted part can be referred to corresponding part in 3GPP TS 32.255 V17.11.0, V18.0.1, V18.1.0 or V17.8.0.

Table 5.2.1.6.1: Default Chargeable events in SMF for QBC

Table 5.2.1.6.2: Chargeable events and their related actions in SMF for QBC

5.2.2.11.7 EPS to 5GS handover for roaming in Home routed scenario

2ch-a. SMF in VPLMN creates a Charging Identifier (visited created Charging Identifier) for the PDU session and sends the Charging Data Request [Initial] to CHF in VPLMN. The new V-SMF can indicate V-CHF that it’s the first record in new V-SMF after inter serving node change.

5.2.2.14.9 Roaming Home routed PDU session -inter-PLMN V-SMF change

“”“” “”

4ch-b. A Charging Data Request [Initial] is sent to new V-CHF, indicating "in-bound roamer" and "Charging Identifier 1" received on step 4b. The new V-SMF can indicate V-CHF that it’s the first record in new V-SMF after inter serving node change.

7ch-a. A Charging Data Request [Termination] is sent to old V-CHF, with "Charging Identifier 1" . The old V-SMF can indicate V-CHF that it’s the last record in the old V-SMF after inter serving node change by VSMF_CHANGE trigger.

“

5.2.2.14.10 Roaming Home routed PDU session -intra-PLMN V-SMF change

4ch-a. A Charging Data Request [Initial] is sent to V-CHF, indicating "in-bound roamer" and "Charging Identifier 1" received on step 4b. The new V-SMF can indicate V-CHF that it’s the first record in new V-SMF after inter serving node change.

“”“”

4ch-d. A Charging Data Request [Termination] is sent to V-CHF, with "Charging Identifier 1" . The old V-SMF can indicate V-CHF that it’s the last record in the old V-SMF after inter serving node change.

6.2.1.2 Definition of PDU session charging information

Table 6.2.1.2.1: Structure of PDU Session Charging Information

In an embodiment, a change of 3GPP TS 32.291 releases 17 and 18 (such as 3GPP TS 32. 291 V18.2.0, V18.3.0, V17.8.0, etc. ) may be as following. The underlined descriptions are newly amended based on the mentioned current specification. The omitted parts can be referred to in the mentioned current specification.

First change

6.1.6.2.2.8 Type PDUSessionInformation

6.1.6.3.6 Enumeration: TriggerType

Table 6.1.6.3.6-1: Enumeration TriggerType

A.2 Nchf_ConvergedCharging API

In an embodiment, a change of 3GPP TS 32.298 releases 17 and 18 (such as 3GPP TS 32. 298 V18.2.0, V18.3.0, V17.8.0, etc. ) may be as following. The underlined descriptions are newly amended based on the mentioned current specification. The omitted parts can be referred to in the mentioned current specification.

5.2.5.2 CHF CDRs

This subclause contains the abstract syntax definitions that are specific to the CHF CDR types defined in this document.

Claims

A method (400) performed by a first network node implementing a session management function (SMF) , comprising:

sending (402) , during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging, wherein the initial charging data request comprises trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure; and/or

sending (404) , during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging, wherein the termination charging data request comprises trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.
The method according to claim 1, wherein when the terminal device moves to the first network node during the mobility procedure, the trigger information is used by the second network node to include the trigger information in a first charging data record when the second network node generates the first charging data record with the first network node.
The method according to claim 1, wherein when the terminal device leaves from the first network node during the mobility procedure, the trigger information is used by the second network node to include the trigger information in a last charging data record when the second network node generates the last charging data record with the first network node.
The method according to any of claims 1-3, wherein the trigger information comprises an event trigger.
The method according to any of claims 1-4, wherein the mobility procedure comprises at least one of:

the terminal device moves from evolved packet system (EPS) to fifth generation system (5GS) with visited SMF insertion,

the terminal device moves from a non Third Generation Partnership Project access network to 5GS with visited SMF insertion,

the terminal device moves from home public land mobile network (PLMN) to visited PLMN in 5GS with visited SMF insertion,

the terminal device moves from a visited PLMN to another visited PLMN with visited SMF change, or

the terminal device moves in a same visited PLMN with visited SMF change.
The method according to any of claims 1-5, wherein the first network node comprises a visited session management function (SMF) and the second network node comprises a visited charging function (CHF) .
The method according to any of claims 1-6, wherein the trigger information is used to identify session continuity.
A method (500) performed by a second network node implementing charging, comprising:

receiving (502) , during a mobility procedure of a terminal device with visited SMF change, an initial charging data request from a first network node implementing a session management function (SMF) , wherein the initial charging data request comprises trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure; and/or

receiving (504) , during a mobility procedure of a terminal device with visited SMF change, a termination data request from a first network node implementing a SMF, wherein the termination charging data request comprises trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.
The method according to claim 8, further comprising: when the terminal device moves to the first network node during the mobility procedure,

including (602) the trigger information in a first charging data record when the second network node generates the first charging data record with the first network node.
The method according to claim 8, further comprising: when the terminal device leaves from the first network node during the mobility procedure,

including (604) the trigger information in a last charging data record when the second network node generates the last charging data record with the first network node.
The method according to any of claims 8-10, wherein the trigger information comprises an event trigger.
The method according to any of claims 8-11, wherein the mobility procedure comprises at least one of:

the terminal device moves from evolved packet system (EPS) to fifth generation system (5GS) with visited SMF insertion,

the terminal device moves from a non Third Generation Partnership Project access network to 5GS with visited SMF insertion,

the terminal device moves from home public land mobile network (PLMN) to visited PLMN in 5GS with visited SMF insertion,

the terminal device moves from a visited PLMN to another visited PLMN with visited SMF change, or

the terminal device moves in a same visited PLMN with visited SMF change.
The method according to any of claims 8-12, wherein the first network node comprises a visited session management function (SMF) and the second network node comprises a visited charging function (CHF) .
The method according to any of claims 8-13, wherein the trigger information is used to identify session continuity.
A first network node implementing a session management function (SMF) (800) , comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said first network node (800) is operative to:

send, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request to a second network node implementing charging, wherein the initial charging data request comprises trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure; and/or

send, during a mobility procedure of a terminal device with visited SMF change, a termination charging data request to a second network node implementing charging, wherein the termination charging data request comprises trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.
The first network node according to claim 15, wherein the first network node is further operative to perform the method of any one of claims 2 to 7.
A second network node implementing charging (800) , comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said second network node (800) is operative to:

receive, during a mobility procedure of a terminal device with visited SMF change, an initial charging data request from a first network node implementing a session management function (SMF) , wherein the initial charging data request comprises trigger information as an indication of insertion of the first network node when the terminal device moves to the first network node during the mobility procedure; and/or

receive, during a mobility procedure of a terminal device with visited SMF change, a termination data request from a first network node implementing a SMF, wherein the termination charging data request comprises trigger information as an indication of removal of the first network node when the terminal device leaves from the first network node during the mobility procedure.
The second network node according to claim 17, wherein the second network node is further operative to perform the method of any one of claims 9-14.
A computer-readable storage medium storing instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 1-14.
A computer program product comprising instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 1-14.