Method and apparatus for selecting network slice admission control function

Abstract

The present disclosure provides a network slice admission control function selection method and device, and relates to the field of communication. The technical scheme of the present application is mainly that the SMF selects the NSACF for the network slice based on the service area information of the NSACF. The NSACF is selected by considering the service area information of the NSACF, so that the appropriate NSACF can be selected more accurately and with less signaling and function interaction.

Description

Technical Field

[0001] This disclosure relates to the field of mobile communication technology, and in particular to a method and apparatus for selecting a Network Slice Admission Control Function (NSACF). Background Technology

[0002] Network slicing technology allows operators to provide various customized networks, such as networks with different functional requirements or different performance requirements, such as different latency, mobility, availability, reliability, and data rate bandwidth requirements; or to provide network functions only for specific users, such as multimedia system users, public safety users, corporate customers, roamers, or mobile virtual network operator (MVNO) hosting.

[0003] Currently, Network Functions (NFs) typically utilize Network Repository Functions (NRFs) for discovery and selection. However, selecting a suitable NSACF that facilitates the monitoring and statistical execution of network slice UE counts and slice session counts—for example, reducing signaling interactions, minimizing function switching due to UE mobility, and optimizing function execution—remains a critical issue that urgently needs to be addressed. Summary of the Invention

[0004] This disclosure presents a method and apparatus for selecting NSACFs, which can select the appropriate NSACF more accurately and with less signaling and functional interaction.

[0005] A first aspect of this disclosure provides a method for selecting an NSACF, the method being executed by a first session management function (SMF), the method comprising: selecting an NSACF for a network slice based on the service area information of the NSACF, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0006] Optionally, the service area information includes any one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0007] Optionally, selecting an NSACF for a network slice includes: if an NSACF has already been selected for the network slice and the service area information of the NSACF indicates that the selected NSACF can be used for the network slice, maintaining the selected NSACF for the network slice.

[0008] Optionally, selecting an NSACF for a network slice includes: if multiple NSACFs have been selected for the network slice and the service area information of the multiple NSACFs indicates that the selected multiple NSACFs can be used for the network slice, selecting an NSACF for the network slice from the multiple selected NSACFs.

[0009] Optionally, selecting an NSACF for the network slice from a plurality of selected NSACFs includes: selecting an NSACF for the network slice based on the service capabilities of the NSACF; wherein the service capabilities include at least one of the following: a first service capability that supports monitoring the number of registered user equipment (UE) of the network slice, and a second service capability that supports monitoring the number of PDU creation sessions of the network slice.

[0010] Optionally, selecting an NSACF for a network slice includes: if one or more NSACFs have been selected for the network slice and the service area information of the one or more NSACFs indicates that none of the selected one or more NSACFs should be used for the network slice, selecting an NSACF that does not belong to the one or more selected NSACFs for the network slice.

[0011] Optionally, if there is an operator service area policy, selecting an NSACF for the network slice includes: selecting an NSACF for the network slice based on the service area information of the NSACF and the operator service area policy; wherein the operator service area policy includes specific rules formulated by the operator to perform NSACF selection based on the service area information.

[0012] Optionally, the operator service area policy is pre-configured in at least one of the first SMF and network storage function NRF.

[0013] Optionally, selecting an NSACF for a network slice includes: selecting an NSACF for the network slice from the registered NSACFs in the NRF, wherein the NRF stores configuration information of the registered NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

[0014] Optionally, selecting an NSACF for a network slice includes: selecting an NSACF for the network slice from the pre-configured NSACFs of the first SMF, wherein the first SMF stores configuration information of the pre-configured NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

[0015] Optionally, selecting an NSACF for a network slice includes: after receiving a PDU session creation request or a PDU session update request from a UE via the Access and Mobility Management Function (AMF), selecting an NSACF for a network slice, wherein the PDU session creation request and the PDU session update request carry S-NSSAIs.

[0016] Optionally, after selecting an NSACF for the network slice, the method further includes: sending a session count validity check and update request to the selected NSACF, the session count validity check and update request including the S-NSSAIs and an update flag, wherein the update flag indicates an increase in the number of PDU sessions created; and receiving a session count validity check and update response message from the selected NSACF, and performing PDU session creation or PDU session update based on the session count validity check and update response message.

[0017] Optionally, the step of creating or updating a PDU session based on the session count validity check and update response message includes: if the session count validity check and update response message indicates that the validity check is successful, executing the PDU session creation process, and returning a session creation acceptance message or a session update acceptance message to the UE via the AMF after completing the PDU session creation; and if the session count validity check and update response message indicates that the validity check fails, returning a session creation rejection message or a session update rejection message to the UE via the AMF.

[0018] Optionally, the method further includes: receiving a PDU session release request from a UE via an AMF, wherein the PDU session release request carries S-NSSAIs; in response to the PDU session release request, sending a session count validity check and update request to an NSACF selected for the network slice identified by the S-NSSAIs, the session count validity check and update request including the S-NSSAIs and an update flag, wherein the update flag indicates a reduction in the number of PDU sessions created; and receiving a session count validity check and update response message from the selected NSACF, and releasing the PDU session according to the session count validity check and update response message.

[0019] A second aspect of this disclosure provides an NSACF selection apparatus applied to a first session management function (SMF). The apparatus includes a processing module configured to select an NSACF for a network slice based on NSACF service area information, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0020] Optionally, the service area information includes any one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0021] Optionally, the processing module is configured to: if an NSACF has been selected for the network slice and the service area information of the NSACF indicates that the selected NSACF can be used for the network slice, maintain the selected NSACF being selected for the network slice.

[0022] Optionally, the processing module is configured to: if multiple NSACFs have been selected for the network slice and the service area information of the multiple NSACFs indicates that the selected multiple NSACFs can be used for the network slice, select an NSACF for the network slice from the selected multiple NSACFs.

[0023] Optionally, the processing module is configured to: select an NSACF for the network slice from a plurality of selected NSACFs based on the service capabilities of the NSACF; wherein the service capabilities include at least one of the following: a first service capability that supports monitoring the number of registered user equipment (UE) of the network slice, and a second service capability that supports monitoring the number of PDU creation sessions of the network slice.

[0024] Optionally, the processing module is configured to: if one or more NSACFs have been selected for the network slice and the service area information of the one or more NSACFs indicates that none of the selected one or more NSACFs should be used for the network slice, select an NSACF that does not belong to the one or more selected NSACFs for the network slice.

[0025] Optionally, the processing module is configured to: select an NSACF for the network slice based on the NSACF service area information and the operator's service area policy; wherein the operator's service area policy includes specific rules formulated by the operator to perform NSACF selection based on the service area information.

[0026] Optionally, the operator service area policy is pre-configured in at least one of the first SMF and network storage function NRF.

[0027] Optionally, the processing module is configured to: select an NSACF for the network slice from the registered NSACFs of the NRF, wherein the NRF stores configuration information of the registered NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

[0028] Optionally, the processing module is configured to: select an NSACF for the network slice from the pre-configured NSACFs of the first SMF, wherein the first SMF stores configuration information of the pre-configured NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

[0029] Optionally, the apparatus further includes: a transceiver module configured to receive a PDU session creation request or a PDU session update request from a UE via an Access and Mobility Management Function (AMF), wherein the PDU session creation request and the PDU session update request carry S-NSSAIs; wherein the processing module is configured to: select an NSACF for a network slice after the transceiver module receives the PDU session creation request or the PDU session update request.

[0030] Optionally, the transceiver module is further configured to: send a session count validity check and update request to a selected NSACF, the session count validity check and update request including the S-NSSAIs and an update flag, wherein the update flag indicates an increase in the number of PDU sessions created; and receive a session count validity check and update response message from the selected NSACF; and the processing module is further configured to perform PDU session creation or PDU session update based on the session count validity check and update response message.

[0031] Optionally, the processing module is further configured to: if the session count validity check and update response message indicates that the validity check is successful, execute the PDU session creation procedure or the PDU session update procedure, and after completing the PDU session creation or PDU session update, instruct the transceiver module to return a session creation acceptance message or a session update acceptance message to the UE via the AMF; and if the session count validity check and update response message indicates that the validity check fails, instruct the transceiver module to return a session creation rejection message or a session update rejection message to the UE via the AMF.

[0032] Optionally, the apparatus further includes a transceiver module configured to receive a PDU session release request from a UE via an AMF, wherein the PDU session release request carries S-NSSAIs; in response to the PDU session release request, send a session count validity check and update request to an NSACF selected for the network slice identified by the S-NSSAIs, the session count validity check and update request including the NSSAIs and an update flag, wherein the update flag indicates a reduction in the number of PDU sessions created; and receive a session count validity check and update response message from the selected NSACF; wherein the processing module is configured to release the PDU session according to the session count validity check and update response message.

[0033] A third aspect of this disclosure provides a communication device, including: a transceiver; a memory; and a processor, respectively connected to the transceiver and the memory, configured to control the transmission and reception of wireless signals of the transceiver by executing computer-executable instructions on the memory, and capable of implementing the NSACF selection method of the first aspect embodiment described above.

[0034] A fourth aspect of this disclosure provides a computer storage medium storing computer-executable instructions; when executed by a processor, the computer-executable instructions can implement the NSACF selection method of the first aspect embodiment described above.

[0035] This disclosure provides a method and apparatus for selecting NSACFs. The SMF selects NSACFs for network slices based on the service area information of the NSACFs. By considering the service area information of the NSACFs when selecting NSACFs, the appropriate NSACF can be selected more accurately and with less signaling and function interaction.

[0036] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0037] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0038] Figure 1 This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0039] Figure 2 This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0040] Figure 3This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0041] Figure 4 This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0042] Figure 5 This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0043] Figure 6 This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0044] Figure 7 This is a flowchart illustrating an NSACF selection method according to an embodiment of the present disclosure;

[0045] Figure 8 This is an interactive process for the selection of NSACF, validity checks on the number of PDU sessions created, and updates, according to embodiments of this disclosure.

[0046] Figure 9 This describes the interactive process for selecting NSACF, validating the number of PDU sessions created, and updating the PDU session creation process according to embodiments of this disclosure.

[0047] Figure 10 This is an interactive process for validating and updating the number of PDU sessions created in the event of PDU session release, according to embodiments of this disclosure.

[0048] Figure 11 A schematic diagram of the structure of an NSACF selection device provided in an embodiment of this disclosure;

[0049] Figure 12 A schematic diagram of the structure of an NSACF selection device provided in an embodiment of this disclosure;

[0050] Figure 13 This is a schematic diagram of the structure of a communication device provided in an embodiment of the present disclosure;

[0051] Figure 14 This is a schematic diagram of the structure of a chip provided in an embodiment of the present disclosure. Detailed Implementation

[0052] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0053] Network slicing technology allows operators to offer a variety of customized networks, for example, if there are differences in functional requirements (e.g., priority, billing, policy control, security, and mobility), if there are differences in performance requirements (e.g., latency, mobility, availability, reliability, and data speed), or if services are only available to specific users (e.g., multimedia system users, public safety users, corporate customers, roamers, or mobile virtual network operator hosting).

[0054] Network slicing can provide complete network functionality, including wireless access network functions, core network functions, and IP Multimedia Subsystem (IMS) functions. A network can support one or more network slices. Network slices differ due to variations in supported network functions and performance. A network slice instance refers to the instantiation of a network slice; that is, the set of deployed network functions that deliver the expected network slice services based on the network slice template.

[0055] Each network slice can support different features and network function optimizations. Each network slice can have different Single-Network Slice Selection Assistance Information (S-NSSAI) to identify different slices or service types, and they have different slice / service types.

[0056] Operators can deploy multiple network slices for different groups or categories of UEs that provide the same functionality, for example, by transmitting different service characteristics or providing a dedicated network for each user. In such scenarios, the slices may be of the same type but are identified separately using different S-NSSAIs.

[0057] The selection of a set of network slice instances for a UE is typically triggered by the first Access and Mobility Management Function (AMF) in the registration process, which interacts with the Network Slice Selection Function (NSSF). Slice selection may result in AMF reselection. A Protocol Data Unit (PDU) session belongs to, and belongs only to, a specific network slice instance within the Public Land Mobile Network (PLMN). Although different network slice instances may have PDU sessions using specific slices of the same DNN, different network slice instances do not share the same PDU session. During handover, the source AMF selects the target AMF by interacting with the Network Repository Function (NRF).

[0058] A Network Slice Type (NEST) is applied to network slices, and multiple network slice instances can be deployed within a single network slice. A Generic Network Slice Template (GST) defines the attributes supported by a network slice. For example, 1) Number of endpoints, which describes the maximum number of endpoints that can simultaneously use the network slice; and 2) Number of connections, which describes the maximum number of concurrent sessions supported by the network slice. This is an important input for determining the size of a network slice and providing sufficient resources for it.

[0059] Network slicing can support a limited number of user equipment (UEs) using the network slice simultaneously and a limited number of concurrent sessions. To support control over the number of terminals and Protocol Data Unit (PDU) sessions within a network slice, a Network Slice Admission Control Function (NSACF) is introduced in 5G communication systems. For network slices subject to Network Slice Admission Control (NSACF), the NSACF monitors the number of registered UEs and the number of PDU sessions in each network slice.

[0060] Multiple NSACFs or multiple NSACF instances can be deployed in a network. In carrier networks, the following different NSACF deployment schemes are possible: Multiple NSACFs deployed on a single network slice; multiple NSACFs serving multiple network slices within a large network for flexibility; single or multiple NSACFs dedicated to a specific network slice to provide customized services, such as isolated slices. Furthermore, all of these schemes can be implemented when multiple network slice instances are deployed within a single network slice.

[0061] Regarding NSACF discovery and selection, Network Functions (NFs) typically utilize Network Repository Functions (NRFs) for execution. The discovery-side network function can perform NSACF discovery and selection via NRF or operator policies such as local configuration. This approach is suitable for discovering and selecting NSACF functions or instances. However, how to more accurately select suitable NSACFs with less signaling, thereby facilitating the implementation of network slice UE number monitoring and statistics functions and slice session number monitoring and statistics functions—for example, by reducing signaling or function interactions and supporting and optimizing function execution—remains a critical issue that urgently needs to be addressed.

[0062] Multiple NSACFs can be deployed in a PLMN, but how to select the appropriate NSACF more accurately with less signaling or functional interaction remains a key issue that needs to be addressed.

[0063] Therefore, the purpose of this disclosure is to: select a suitable NSACF considering factors such as the need for an NSACF in each area; select a suitable NSACF with less signaling, such as less transmission of network slice status notifications and reports or NF device relocation; and select a suitable NSACF with greater accuracy.

[0064] This disclosure proposes a method and apparatus for selecting NSACFs. The SMF selects NSACFs for network slices based on the service area information of the NSACFs. By considering the service area information of the NSACFs, the appropriate NSACF can be selected more accurately and with less signaling and function interaction.

[0065] The method and apparatus for selecting NSACF provided in this application will be described in detail below with reference to the accompanying drawings.

[0066] Figure 1 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. Figure 1As shown, this method can be executed by a Session Management Function (SMF). In the following text, the SMF that executes the selection method of the NSACF may be referred to as the first SMF, and includes the following steps.

[0067] S101, based on the service area information of NSACF, select an NSACF for the network slice, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0068] While multiple NSACFs can be deployed in networks such as PLMNs, there is currently a lack of effective technical means to select the appropriate NSACF from a large number of NSACFs.

[0069] Therefore, this application provides a method for selecting an NSACF, wherein the first SMF selects an NSACF for a network slice based on the service area information of the NSACF.

[0070] It should be noted that the NSACF selection method in this embodiment also applies when the deployed NSACF has multiple NSACF instances. That is, the NSACF instance can be selected based on the service area information of the NSACF instance. Specific details will not be elaborated here.

[0071] In some embodiments, service area information may include one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0072] NSACF service area information can include a list of Tracking Area Identity (TAI) entries. The first SMF can select an NSACF for network slices based on the NSACF's TAI list. A Tracking Area (TA) is defined as a free-moving area where a User Equipment (UE) does not need to update services. A TA is a cell-level configuration; multiple cells can be configured with the same TA, and a cell can only belong to one TA. The TAI is the TA identifier, composed of a PLMN and a Tracking Area Code (TAC). Multiple TAs can form a TA list and be assigned to a single UE. When a UE moves within this TA list, it does not need to perform a TA update to reduce frequent interactions with the network. When a UE enters a new TA not in its registered TA list, a TA update is required, resulting in the UE being reassigned to a new set of TAs. For example, in the case of UE PDU session creation, the first SMF needs to select NSACF for the corresponding network slice (e.g., by the S-NSSAIs identifier included in the PDU session creation request from the UE). If the service area information of the NSACF includes a TAI list, the first SMF can select the NSACF based on the TAI list of the NSACF to monitor the number of PDU session creations for that network slice. The TAI list of the selected NSACF may include, for example, the identifier of the TA in the TA list assigned to the UE.

[0073] The service area information of the NSACF may include the service area information of the SMF. The first SMF selects an NSACF for the network slice based on the service area information of the SMF contained in the NSACF. For example, in the case of UE PDU session creation, the first SMF needs to select an NSACF for the corresponding network slice (e.g., by the S-NSSAIs identifier included in the PDU session creation request from the UE). If the service area information of the NSACF includes the service area information of the SMF, the first SMF can select an NSACF based on the service area information of the SMF contained in the NSACF to monitor the number of PDU sessions created for that network slice. The service area information of the SMF contained in the selected NSACF is, for example, the service area information of the first SMF.

[0074] The service area information of the NSACF may include service area information of one or more User Plane Functions (UPFs) controlled by the SMF. The first SMF selects an NSACF for a network slice based on the service area information of the UPFs possessed by the NSACF. For example, in the case of UE PDU session creation, the first SMF needs to select an NSACF for the corresponding network slice (e.g., by the S-NSSAIs identifier included in the PDU session creation request from the UE). If the service area information of the NSACF includes the service area information of the UPFs, the first SMF can select the NSACF based on the service area information of the UPFs possessed by the NSACF to monitor the number of PDU session creations for that network slice. The service area information of the UPFs possessed by the selected NSACF is, for example, the service area information of the UPFs controlled by the first SMF.

[0075] According to the NSACF selection method of this implementation, the SMF can select an NSACF for network slices based on the NSACF's service area information. By taking into account the NSACF's service area information, a suitable NSACF can be selected more accurately and with less signaling and function interaction.

[0076] Figure 2 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. This method can be executed by a first SMF, such as... Figure 2 As shown, the method may include the following steps.

[0077] S201, Based on the service area information of NSACF, select an NSACF for the network slice, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0078] In some embodiments, service area information may include one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0079] For specific details about S201, please refer to [link / reference]. Figure 1 Step S101 and its related descriptions will not be repeated here.

[0080] In this embodiment, step S201 may include any of the following steps.

[0081] S2011, if an NSACF has been selected for network slicing and the service area information of the NSACF indicates that the selected NSACF can be used for network slicing, maintain the selected NSACF for network slicing.

[0082] When the first SMF selects an NSACF for a network slice, there is a situation where an NSACF has already been selected for that network slice. For example, since an NSACF may have been selected for the corresponding network slice during the UE's PDU session creation process, the above situation may occur if the S-NSSAIs carried in the PDU session update request still identify the network slice in the case of UE PDU session update.

[0083] In this case, if the service area information of the selected NSACF indicates that it can be used for the network slice, the first SMF will still select the NSACF to monitor the number of PDU creation sessions for the network slice, that is, maintain the selected NSACF for the network slice.

[0084] For example, as referenced Figure 1 As shown in the embodiments, when the service area information of the selected NSACF is a TAI list, if the TAI list includes the identifier of the TA in the TA list allocated to the UE of the service requesting to monitor the number of PDU creation sessions for the network slice, it indicates that the selected NSACF can be used for the network slice, and the first SMF maintains the number of PDU creation sessions for the selected NSACF used to monitor the network slice. Similarly, when the service area information of the selected NSACF is the service area information of an SMF, if the service area information of the SMF possessed by the selected NSACF is the service area information of the first SMF, it indicates that the selected NSACF can be used for the network slice, and the first SMF maintains the number of PDU creation sessions for the selected NSACF used to monitor the network slice. For example, when the selected NSACF service area information is the UPF service area information, if the selected NSACF has UPF service area information that is a UPF service area information controlled by the first SMF, it means that the selected NSACF can be used for the network slice, and the first SMF maintains the number of PDU creation sessions used by the selected NSACF to monitor the network slice.

[0085] S2012, if multiple NSACFs have been selected for network slicing and the service area information of the multiple NSACFs indicates that the selected multiple NSACFs can be used for network slicing, select an NSACF for network slicing from the selected multiple NSACFs.

[0086] When the first SMF selects an NSACF for a network slice, there may be a situation where multiple NSACFs have already been selected for that network slice.

[0087] In this case, if the service area information of the selected NSACFs indicates that the selected NSACFs can be used for the network slice, then the first SMF can select from the selected NSACFs the NSACFs used to monitor the number of PDU creation sessions for the network slice.

[0088] In some embodiments, step S2012 may include the following steps:

[0089] S20121, based on the service capabilities of NSACF, selects an NSACF for network slicing from multiple selected NSACFs.

[0090] The service capabilities include at least one of the following: a first service capability that supports the number of registered user equipment (UE) devices for monitoring network slices, and a second service capability that supports the number of PDU sessions created for monitoring network slices.

[0091] NSACFs can have various service capabilities. For example, an NSACF might only support the number of registered UEs monitoring a network slice, or it might only support the number of PDU session creations for monitoring a network slice, or it might support both the number of registered UEs monitoring a network slice and the number of PDU session creations for monitoring a network slice. If an NSACF is selected directly without considering its service capabilities, it's possible to choose an NSACF that doesn't meet the requirements. For instance, in the PDU session creation scenario, if the first SMF directly selects an NSACF for a network slice without considering its service capabilities, it might select an NSACF that doesn't have the capability to support the number of PDU session creations for monitoring a network slice, thus selecting an NSACF that doesn't meet the requirements.

[0092] Therefore, when the first SMF selects an NSACF for a network slice from multiple selected NSACFs, it can also consider the service capabilities of the NSACF to achieve the selection of the NSACF.

[0093] Specifically, the first SMF can select an NSACF from among the selected NSACFs that has the service capability to only support monitoring the number of PDU creation sessions for the network slice, or select an NSACF that has the service capability to support both the number of registered UEs monitoring the network slice and the number of PDU creation sessions for the network slice, for monitoring the number of PDU creation sessions for that network slice.

[0094] S2013, if one or more NSACFs have been selected for network slicing and the service area information of one or more NSACFs indicates that none of the selected one or more NSACFs should be used for network slicing, select an NSACF that does not belong to the one or more selected NSACFs for network slicing.

[0095] As mentioned above, when the first SMF selects an NSACF for a network slice, there is a situation where one or more NSACFs have already been selected for that network slice.

[0096] In this case, if the service area information of the selected one or more NSACFs indicates that none of the selected one or more NSACFs should be used for the network slice, then the first SMF selects a new NSACF for the network slice to monitor the number of PDU creation sessions for the network slice. This new NSACF does not belong to the selected one or more NSACFs.

[0097] For example, as referenced Figure 1 As shown in the embodiments, when the service area information of one or more NSACFs is a TAI list, if the TAI list of each of the selected one or more NSACFs does not include the identifier of the TA in the TA list allocated to the UE of the service requesting to monitor the number of PDU creation sessions for the network slice, it indicates that the selected one or more NSACFs are not suitable for the network slice, and the first SMF selects a new, more suitable NSACF for the network slice to monitor the number of PDU creation sessions for the network slice. Similarly, when the service area information of one or more NSACFs is the service area information of an SMF, if the service area information of the SMF possessed by each of the selected one or more NSACFs is not the service area information of the first SMF, it indicates that the selected one or more NSACFs are not suitable for the network slice, and the first SMF selects a new, more suitable NSACF for the network slice to monitor the number of PDU creation sessions for the network slice. For example, when the service area information of one or more NSACFs is selected as the service area information of UPFs, if the UPF service area information of each of the selected one or more NSACFs is not the service area information of the UPF controlled by the first SMF, it means that the selected one or more NSACFs are not suitable NSACFs for the network slice. The first SMF selects a new and more suitable NSACF for the network slice to monitor the number of PDU sessions created for the network slice.

[0098] According to the NSACF selection method of this implementation, SMF can select an NSACF for network slicing by considering the service area information of the selected NSACF when an existing NSACF has been selected for network slicing. This allows for more accurate selection of a suitable NSACF with less signaling and function interaction.

[0099] Figure 3 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. This method can be executed by a first SMF, such as... Figure 3As shown, the method may include the following steps.

[0100] S301, Based on the service area information of NSACF, select an NSACF for the network slice, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0101] In some embodiments, service area information may include one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0102] For specific details about the S301, please refer to [link / reference]. Figure 1 The relevant description of step S101 will not be repeated here.

[0103] In this embodiment, when there is an operator service area policy, the following steps can be used to select NSACF for network slices.

[0104] S3011 selects NSACF for network slicing based on NSACF service area information and operator service area policies.

[0105] The operator service area policy includes specific rules formulated by the operator to perform NSACF selection based on the service area information.

[0106] In this embodiment, when there is an operator service area policy, the first SMF selects an NSACF for the network slice based on the operator service area policy and the service area information of the NSACF, so that the selected NSACF can meet the operator service area policy.

[0107] Operator service area policies may include TAI lists, SMF service area information, policy priorities for service area information of one or more UPFs controlled by the SMF, priorities of various NSACFs with service capabilities supporting the monitoring of the number of PDU creation sessions for network slices, location information of UEs requesting monitoring of the number of PDU creation sessions for network slices, or registration tracking area information of UEs requesting monitoring of the number of PDU creation sessions for network slices, etc. It should be noted that the operator service area policies listed herein are merely examples. In practical applications, each operator can formulate various different operator service area policies according to its own needs, and this application does not impose any restrictions on this.

[0108] For example, as referenced Figure 1As shown in the embodiment, when the service area information of NSACF is a TAI list, if the operator's service area policy is to select an NSACF whose TAI list completely matches the number of PDU creation sessions of the UE requesting to monitor the network slice, then the first SMF selects an NSACF that satisfies the operator's service area policy for the network slice based on the TAI list of the NSACF. Specifically, for example, if there are three NSACFs, denoted as NSACF1-NSACF3, where the TAI list of NSACF1 includes the identifier TAI1 of TA1, the identifier TAI2 of TA2, and the identifier TAI3 of TA3; the TAI list of NSACF2 includes the identifier TAI1 of TA1, the identifier TAI2 of TA2, and the identifier TAI4 of TA4; and the TAI list of NSACF3 includes the identifier TAI1 of TA1, the identifier TAI3 of TA3, and the identifier TAI4 of TA4, and the TA list assigned to the UE requesting to monitor the number of PDU creation sessions for the network slice includes TA1, TA2, and TA3, then the first SMF will select NSACF1 to monitor the number of PDU creation sessions for that network slice because the TAI list of NSACF1 completely matches the TA list assigned to the UE, which conforms to the operator's service area policy.

[0109] For example, if the operator's service area policy prioritizes the service area information of one or more UPFs controlled by the SMF, then the first SMF will select an NSACF for the network slice based on the TAI list of the NSACF, considering the service area information of the UPF controlled by the first SMF. Specifically, since the operator's service area policy prioritizes the service area information of the UPF, the first SMF can select an NSACF whose TAI list matches the service area information of the UPF controlled by the first SMF.

[0110] In some embodiments, the operator service area policy is pre-configured in at least one of the first SMF and NRF.

[0111] The carrier service area policy can be pre-configured in the first SMF or in the NRF. When the carrier service area policy is pre-configured in the NRF, the first SMF can obtain the carrier service area policy by accessing the NRF.

[0112] In some embodiments, if an NSACF has been selected for network slicing and both the NSACF's service area information and the operator's service area policy indicate that the selected NSACF can be used for network slicing, then the first SMF maintains that the selected NSACF has been selected for network slicing.

[0113] For example, when the service area information of the selected NSACF is a TAI list and the operator's service area policy is to select an NSACF whose TAI list completely matches the TA list of the UE that requests to monitor the number of PDU creation sessions for the network slice, if the TAI list of the selected NSACF completely matches the TA list assigned to the UE, it means that the selected NSACF can be used for the network slice, and the first SMF maintains the number of PDU creation sessions for the selected NSACF to monitor the network slice.

[0114] In some embodiments, if multiple NSACFs have been selected for network slicing and both the NSACF service area information and the operator service area policy indicate that the selected multiple NSACFs can be used for network slicing, then the first SMF selects an NSACF for network slicing from the selected multiple NSACFs. Specifically, the first SMF can select an NSACF for network slicing based on the service capabilities of the NSACF; relevant details can be found in [reference needed]. Figure 2 The relevant description of step S2012 in the document.

[0115] In some embodiments, if one or more NSACFs have been selected for network slicing but the service area information of the NSACFs or the operator's service area policy indicates that each selected NSACF should not be used for network slicing, then the first SMF selects an NSACF that does not belong to the one or more selected NSACFs for network slicing based on the operator's service area policy and the service area information of the NSACFs.

[0116] For example, when one or more service area information is selected as a TAI list and the operator's service area policy is to select an NSACF with a TAI list that completely matches the TA list of the UE requesting to monitor the number of PDU creation sessions of the network slice, if the TAI list of each of the selected NSACFs does not include the identifier of the TA in the TA list assigned to the UE requesting to monitor the number of PDU creation sessions of the network slice, or if the TAI list of some of the selected NSACFs includes the identifier of the TA in the TA list assigned to the UE but does not completely match the TA list assigned to the UE, it means that none of the selected NSACFs are suitable for the network slice. The first SMF selects a new, more suitable NSACF for the network slice to monitor the number of PDU creation sessions of the network slice.

[0117] According to the NSACF selection method of this implementation, if there is an operator service area policy, the SMF will select an NSACF based on the service area information of the NSACF according to the operator service area policy, so that the selected NSACF can meet the operator service area policy.

[0118] Figure 4 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. This method can be executed by a first SMF, such as... Figure 4 As shown, the method may include the following steps.

[0119] S401, Based on the service area information of NSACF, select an NSACF for the network slice, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0120] In some embodiments, service area information may include one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0121] For specific details about the S401, please refer to [link / reference]. Figure 1 The relevant description of step S101 will not be repeated here.

[0122] In this embodiment, step S401 may include any of the following steps.

[0123] S4011, Select an NSACF for network slices from the registered NSACFs in the NRF. The NRF stores the configuration information of the registered NSACFs, including network slice selection assistance information S-NSSAIs and the service area information of the registered NSACFs.

[0124] NSACFs can register with the NRF. NSACFs provide their configuration information to the NRF, which then marks the NSACF as available. During registration, the NSACF provides S-NSSAIs and its service area information; that is, the configuration information of an NSACF registered with the NRF can include S-NSSAIs and their service area information. The first SMF can utilize the NRF to discover and select NSACFs.

[0125] S-NSSAIs can include multiple S-NSSAIs. An S-NSSAI identifies a network slice and is auxiliary information used by the network to select a specific network slice instance. Available S-NSSAI information includes: Slice / Service Type (SST), indicating network slices with different functions and services; and a Serving Differentiator, optional supplementary SST information used to further differentiate network slice instances from all SST-type network slice instances.

[0126] In some embodiments, the first SMF selects an NSACF for network slicing from the registered NSACFs in the NRF based on the NSACF's service area information.

[0127] For details on how the first SMF selects an NSACF based on NSACF service area information, please refer to [link / reference]. Figure 1 The relevant description of step S101 will not be repeated here.

[0128] In some embodiments, if one or more NSACFs have been selected for network slicing and the service area information of one or more NSACFs indicates that none of the selected one or more NSACFs should be used for network slicing, the first SMF selects an NSACF that does not belong to the one or more selected NSACFs from the registered NSACFs in the NRF for network slicing based on the service area information of the NSACFs.

[0129] For specific details on how the first SMF selects an NSACF that does not belong to one or more NSACFs already selected in this situation, please refer to [link / reference]. Figure 2 The relevant description of step S2013 in the process will not be repeated here.

[0130] In some embodiments, when there is an operator service area policy, the first SMF selects an NSACF from the registered NSACFs in the NRF based on the NSACF's service area information and the operator service area policy. Specifically, if one or more NSACFs have already been selected for network slicing, and the service area information or operator service area policy of one or more NSACFs indicates that none of the selected NSACFs should be used for network slicing, the first SMF selects an NSACF from the registered NSACFs in the NRF that does not belong to the one or more selected NSACFs for the network slice, based on the NSACF's service area information and the operator service area policy.

[0131] For details on how the first SMF selects an NSACF based on NSACF service area information and operator service area policies, please refer to [link / reference]. Figure 3 The relevant description of step S3011 will not be repeated here.

[0132] S4012, Select an NSACF from the pre-configured NSACFs of the first SMF, wherein the first SMF stores the configuration information of the pre-configured NSACFs, including S-NSSAIs and service area information of the registered NSACFs.

[0133] The NSACF can be locally configured within the first SMF. The NSACF configuration information can indicate the NSACF's service area information and S-NSSAIs. The first SMF can use the configuration information to discover and select the NSACF.

[0134] In some embodiments, the first SMF selects an NSACF from its pre-configured NSACFs based on the NSACF's service area information.

[0135] For details on how the first SMF selects an NSACF based on NSACF service area information, please refer to [link / reference]. Figure 1 The relevant description of step S101 will not be repeated here.

[0136] In some embodiments, if one or more NSACFs have been selected for network slicing and the service area information of one or more NSACFs indicates that none of the selected one or more NSACFs should be used for network slicing, the first SMF selects an NSACF that does not belong to the one or more selected NSACFs from the pre-configured NSACFs of the first SMF for network slicing based on the service area information of the NSACFs.

[0137] For specific details on how the first SMF selects an NSACF that does not belong to one or more NSACFs already selected in this situation, please refer to [link / reference]. Figure 2 The relevant description of step S2013 in the process will not be repeated here.

[0138] In some embodiments, when there is an operator service area policy, the first SMF selects an NSACF from its pre-configured NSACFs based on the NSACF service area information and the operator service area policy. If one or more NSACFs have already been selected for network slicing, and the service area information or operator service area policy of one or more NSACFs indicates that none of the selected NSACFs should be used for network slicing, the first SMF selects an NSACF from its pre-configured NSACFs that does not belong to the one or more selected NSACFs, based on the NSACF service area information and the operator service area policy.

[0139] For details on how the first SMF selects NSACF service area information and operator service area policies, please refer to [link / reference]. Figure 3 The relevant description of step S3011 will not be repeated here.

[0140] According to the NSACF selection method of this implementation, the SMF can select the appropriate NSACF from the NRF or from local preference, thereby avoiding a complex NSACF selection process and reducing signaling transmission.

[0141] Figure 5 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. This method can be executed by a first SMF, such as... Figure 5 As shown, the method may include the following steps.

[0142] S501, based on the service area information of NSACF, select an NSACF for the network slice, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0143] In some embodiments, service area information may include one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0144] For specific details about the S501, please refer to [link / reference]. Figure 1 The relevant description of step S101 will not be repeated here.

[0145] In this embodiment, NSACF can be selected for network slices through the following steps.

[0146] S5011 After receiving a PDU session creation request or PDU session update request from the UE via the Access and Mobility Management Function (AMF), the NSACF is selected for the network slice, wherein the PDU session creation request and PDU session update request carry S-NSSAIs.

[0147] When a UE requests to create a PDU session, the UE can send a PDU session creation request to the AMF. In response to the PDU session creation request, the AMF sends a PDU session establishment request message to the first SMF. In response to the PDU session establishment request message, the first SMF selects the NSACF for the network slice identified by S-NSSAI based on the service area information of the NSACF.

[0148] When a UE requests to update its PDU session, the UE can send a PDU session update request to the AMF. In response to the PDU session update request, the AMF sends a PDU session update request message to the first SMF. In response to the PDU session update request message, the first SMF selects the NSACF for the network slice identified by S-NSSAI based on the NSACF's service area information.

[0149] For specific details on choosing NSACF for network slices, please refer to [link / reference]. Figure 1 Step S101 in Figure 2 Steps S201 and S2011-S2013 in the process Figure 3 Steps S301 and S3011 in the process Figure 4The relevant descriptions of steps S401 and S4011-S4012 are not repeated here.

[0150] According to the NSACF selection method of this embodiment, the SMF can perform NSACF selection in response to a PDU session creation request or a PDU session update request.

[0151] Figure 6 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. This method can be executed by a first SMF, such as... Figure 6 As shown, the method may include the following steps.

[0152] S601 After receiving a PDU session creation request or PDU session update request from the UE via the Access and Mobility Management Function (AMF), the NSACF is selected for the network slice, wherein the PDU session creation request and the PDU session update request carry S-NSSAIs.

[0153] For specific details about the S601, please refer to [link / reference]. Figure 5 The relevant description of step S5011 in the process will not be repeated here.

[0154] S602, send a session count validity check and update request to the selected NSACF. The session count validity check and update request includes S-NSSAIs and an update flag, where the update flag indicates an increase in the number of PDU sessions created.

[0155] After selecting an NSACF, the first SMF can send a session count validity check and update request message to the selected NSACF, so that the NSACF can perform a check on the number of PDU sessions created based on the session count validity check and update request message.

[0156] S603, receive a session count validity check and update response message from the selected NSACF, and perform PDU session creation or PDU session update based on the session count validity check and update response message.

[0157] In the case of PDU session creation, after receiving the session count validity check and update request message, the NSACF responds to the request message by performing a check on the number of PDU sessions to be created, and updates the number of PDU sessions to be created based on the check result and / or sends a session count validity check and update response message. After receiving the session count validity check and update response message, the first SMF can create a PDU session based on the response message.

[0158] In the case of PDU session updates, after receiving a session count validity check and update request message, the NSACF responds to the request message by checking the number of PDU sessions created, and updates the number of PDU sessions created based on the check result and / or sends a session count validity check and update response message. After receiving the session count validity check and update response message, the first SMF can update the PDU sessions based on the response message.

[0159] In some embodiments, step S603 may include the following steps.

[0160] S6031, if the session validity check and update response message indicate that the validity check is successful, execute the PDU session creation procedure or the PDU session update procedure, and after completing the PDU session creation or PDU session update, return a session creation acceptance message or a session update acceptance message to the UE via the AMF.

[0161] In the case of PDU session creation, if the session count validity check and update response message indicates that the validity check is successful, it means that a PDU session can be created for that network slice. The first SMF then executes the PDU session creation process based on the session count validity check and update response message and returns a session creation acceptance message to the UE via the AMF after completing the PDU session creation process.

[0162] In the case of PDU session update, if the session count validity check and update response message indicate that the validity check is successful, it means that the PDU session can be updated with respect to the network slice. The first SMF then performs the PDU session update procedure based on the session count validity check and update response message and returns a session update acceptance message to the UE via the AMF after the PDU session update procedure is completed.

[0163] S6032, if the session count validity check and update response message indicate that the validity check failed, a session creation rejection message or a session update rejection message is returned to the UE via the AMF.

[0164] In the case of PDU session creation, if the session count validity check and update response message indicates that the validity check has failed, it means that a PDU session cannot be created for that network slice, for example, because the number of PDU sessions to be created for that network slice has reached the maximum. In this case, the first SMF returns a session creation rejection message to the UE via the AMF based on the session count validity check and update response message.

[0165] In the case of PDU session updates, if the session count validity check and update response message indicate that the validity check has failed, it means that the PDU session cannot be updated for that network slice, for example, because the number of PDU sessions created for that network slice has reached the maximum. In this case, the first SMF returns a session update rejection message to the UE via the AMF based on the session count validity check and update response message.

[0166] According to the NSACF selection method in this embodiment, after selecting an NSACF, the SMF can use that NSACF to monitor the number of PDU sessions created for the corresponding network slice.

[0167] Figure 7 A flowchart illustrating an NSACF selection method according to an embodiment of this disclosure is shown. This method can be executed by a first SMF, such as... Figure 7 As shown, the method may include the following steps.

[0168] S701, based on the service area information of NSACF, select an NSACF for the network slice, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0169] In some embodiments, service area information may include one or more of the following: a list of tracking area identifiers; service area information of the SMF; or service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0170] For specific details about the S701, please refer to [link / reference]. Figure 1 Step S101 in Figure 2 Steps S201 and S2011-S2013 in the process Figure 3 Steps S301 and S3011 in the process Figure 4 Steps S401 and S4011-S4012 in the process Figure 5 In the middle steps S501 and S5011, Figure 6 The relevant description of step S601 in the process will not be repeated here.

[0171] S702, receives a PDU session release request from the UE via the AMF, wherein the PDU session release request carries S-NSSAIs.

[0172] When a UE requests to release a PDU session, the UE can send a PDU session release request to the AMF. In response to the PDU session release request, the AMF sends a PDU session release request message to the first SMF.

[0173] S703, in response to the PDU session release request, sends a session count validity check and update request to the NSACF selected for the network slice identified by S-NSSAI. The session count validity check and update request includes the NSSAI and an update flag, wherein the update flag indicates a reduction in the number of PDU sessions created.

[0174] In response to a PDU session release request from a UE, the first SMF locates the NSACF selected for the network slice identified by the S-NSSAI included in the PDU session release request, and sends a session count validity check and update request message to the located NSACF so that the NSACF can perform a check on the number of PDU sessions created based on the session count validity check and update request message.

[0175] S704, receive a session count validity check and update response message from the selected NSACF, and release the PDU session based on the session count validity check and update response message.

[0176] Upon receiving a session count validity check and update request message, the NSACF responds by checking the number of PDU sessions to be created, and updates the number of PDU sessions to be created and / or sends a session count validity check and update response message based on the check result. In this embodiment, since the update flag in the validity check and update request indicates a reduction in the number of PDU sessions to be created, the NSACF reduces the number of PDU sessions to be created according to the update flag, and sends a validity check and update response message to the first SMF after completing the reduction. After receiving the session count validity check and update response message, the first SMF can confirm that the NSACF has updated the number of PDU sessions to be created for the corresponding network slice, thereby releasing the PDU sessions.

[0177] According to the NSACF selection method in this embodiment, after selecting an NSACF, the SMF can use that NSACF to monitor the number of PDU sessions created for the corresponding network slice.

[0178] Figure 8 An interactive process regarding the selection of NSACF, validity checks on the number of PDU sessions created, and updates, according to an embodiment of this disclosure, is illustrated. Figure 8 As shown, the SMF selects the NSACF and interacts with the NSACF to perform validity checks and updates regarding the number of PDU sessions created. Specifically, this includes the following process.

[0179] S801 triggers a validity check and update regarding the number of PDU sessions created.

[0180] The validity check and update of the number of PDU sessions created can be triggered in response to messages received by the SMF from other devices or by the SMF based on a certain preset triggering mechanism.

[0181] For example, validity checks and updates regarding the number of PDU sessions created can be triggered in response to a PDU session creation request from the UE. In the case of PDU session creation, the SMF can consider the S-NSSAIs carried in the PDU session creation request and perform NSACF selection based on the NSACF's service area information. The NSACF's service area information may include one or more of the following: a list of tracking area identifiers; the SMF's service area information; and service area information of one or more User Plane Functions (UPFs) controlled by the SMF. During the NSACF selection process, if an NSACF has already been selected for a network slice and the NSACF's service area information indicates that the selected NSACF can be used for the network slice, the SMF will still select that selected NSACF for the number of PDU sessions created to monitor that network slice. If multiple NSACFs have been selected for network slicing, and the service area information of these NSACFs indicates that they can be used for network slicing, the SMF selects an NSACF from the selected NSACFs to monitor the number of PDU creation sessions for that network slice. For example, the SMF selects an NSACF based on its service capabilities. Furthermore, if there is an operator service area policy, the SMF selects an NSACF for monitoring the number of PDU creation sessions for that network slice based on the NSACF's service area information and the operator service area policy. NSACF selection can be performed during PDU session creation or updating. Additionally, the NSACF selection method described herein also applies to NSACF instance selection.

[0182] An NSACF can register with an NRF. The NSACF provides its configuration information to the NRF, which then marks the NSACF as available. For the PDU session creation process, the NSACF can provide S-NSSAIs and its service area information as input. If the NSACF is registered with the NRF, the SMF can use the NRF to select the NSACF.

[0183] NSACF can be configured within SMF. NSACF configuration information can indicate NSACF service area information and S-NSSAIs. If NSACF is configured within SMF, SMF can use the NSACF configuration information within SMF to select the appropriate NSACF.

[0184] Carrier service area policies can be pre-configured in SMF and / or NRF.

[0185] In another example, a validity check and update regarding the number of PDU sessions created can be triggered in response to a PDU session release request from the UE.

[0186] In yet another example, a validity check and update of the number of PDU sessions created can be triggered in response to a PDU session creation failure.

[0187] S802, SMF sends a validity check and update request message to the selected NSACF.

[0188] The validity check and update request (Nnsacf_NumberOfPDUsPerSliceAvailabilityCheckAndUpdate_Request) message includes S-NSSAIs and an update flag. This update flag can indicate an increase in the number of PDU sessions created if the validity check and request is triggered at the start of the PDU session creation process, or a decrease in the number of PDU sessions created if the validity check and request is triggered at the end of the PDU session release process.

[0189] S803, NSACF performs checks and updates on the number of PDU sessions created based on the validity check and update request messages provided by SMF.

[0190] If the update flag in the validity check and update request message indicates an increase in the number of PDU sessions to be created, and NSACF finds that the number of PDU sessions to be created for the network slice identified by S-NSSAI in the validity check and update request message has not yet reached the maximum, then NSACF will increase the number of PDU sessions to be created.

[0191] If the update flag in the validity check and update request message indicates an increase in the number of PDU sessions to be created, and NSACF finds that the number of PDU sessions to be created for the network slice identified by S-NSSAI in the validity check and update request message has already reached the maximum, then NSACF will not increase the number of PDU sessions to be created and will return a result parameter indicating that the number of PDU sessions to be created for the corresponding network slice has reached the maximum.

[0192] If the update flag in the validity check and update request message indicates a reduction in the number of PDU creation sessions, NSACF will reduce the number of PDU creation sessions for the corresponding network slice.

[0193] S804, NSACF sends a validity check and update response message to SMF.

[0194] When NSACF discovers that the number of PDU sessions created for the corresponding network slice has reached the maximum, the validity check and update response (Nnsacf_NumberOfPDUsPerSliceAvailabilityCheckAndUpdate_Response) message that NSACF sends back to SMF may include the result parameters as described above.

[0195] In the case of PDU session creation, if the NSACF feedback indicates that the number of PDU sessions created for the network slice has reached the maximum number, the SMF will reject the PDU session creation request and return a session creation rejection message to the UE.

[0196] In the event that PDU session creation fails, SMF can trigger a validity check and update on the number of PDU sessions created again, and the validity check and update request message includes an update flag indicating a reduction in the number of PDU sessions created so that the number of PDU sessions created can be readjusted in NSACF.

[0197] For example, Figure 9 This illustration depicts the interactive process of selecting NSACF and checking and updating the validity of the number of PDU sessions created in the context of PDU session creation, according to embodiments of this disclosure. Figure 9 As shown, the SMF selects the NSACF and interacts with the NSACF to perform validity checks and updates on the number of PDU sessions created for that slice. Specifically, this includes the following process.

[0198] S901, the UE sends a PDU session establishment request to the AMF, which carries S-NSSAIs.

[0199] S902, AMF sends a PDU session establishment request message (Nsmf_PDUSession_CreateSMContext_Request) to SMF, which carries S-NSSAIs.

[0200] After receiving a PDU session establishment request message, the SMF may consider the S-NSSAIs carried in the PDU session creation request and perform NSACF selection based on the NSACF service area information. The NSACF service area information may include one or more of the following: a list of tracking area identifiers; the SMF's service area information; and service area information of one or more User Plane Functions (UPFs) controlled by the SMF. In performing NSACF selection, if an NSACF has already been selected for a network slice and its service area information indicates that the selected NSACF can be used for the network slice, the SMF will still select the number of PDU session creations using that selected NSACF to monitor the network slice. If multiple NSACFs have been selected for a network slice and their service area information indicates that multiple NSACFs can be used for the network slice, the SMF will select the number of NSACFs from the selected multiple NSACFs to monitor the network slice's PDU session creation capabilities. For example, the SMF may select the number of NSACFs from the selected multiple NSACFs to monitor the network slice's PDU session creation capabilities. Furthermore, if there is an operator service area policy, the SMF selects an NSACF (Network Service Area Provider) for the network slice based on the NSACF's service area information and the operator's service area policy. This NSACF selection can be performed during PDU session creation or updating. Additionally, the NSACF selection method described herein also applies to the selection of NSACF instances.

[0201] An NSACF can register with an NRF. The NSACF provides its configuration information to the NRF, which then marks the NSACF as available. For the PDU session creation process, the NSACF can provide S-NSSAIs and its service area information as input. If the NSACF is registered with the NRF, the SMF can use the NRF to select the NSACF.

[0202] NSACF can be configured within SMF. NSACF configuration information can indicate NSACF service area information and S-NSSAIs. If NSACF is configured within SMF, SMF can use the NSACF configuration information within SMF to select the appropriate NSACF.

[0203] Carrier service area policies can be pre-configured in SMF and / or NRF.

[0204] S903, SMF performs NSACF discovery.

[0205] If the SMF does not have an NSACF address, it queries the NRF to obtain one. The SMF provides information including the S-NSSAI type and other details to the NRF to retrieve the NSACF address. The NRF obtains the NSACF address for monitoring the number of slice sessions performed on the S-NSSAI and returns it to the SMF. If the SMF already has an NSACF address, this step can be skipped.

[0206] S904, SMF sends a validity check and update request message (Nnsacf_NumberOfPDUsPerSliceAvailabilityCheckAndUpdate_Request) to the selected NSACF.

[0207] S905, NSACF performs a check and update of the number of PDU sessions created.

[0208] S906, NSACF sends a validity check and update response message (Nnsacf_NumberOfPDUsPerSliceAvailabilityCheckAndUpdate_Response) to SMF.

[0209] S907, SMF sends a PDU session establishment response message (Nsmf_PDUSession_CreatSMContext_Response) to AMF.

[0210] S908, the AMF sends a PDU session establishment acceptance / reject message to the UE.

[0211] For example, Figure 10 The interactive process for checking and updating the validity of the number of PDU sessions created in the case of PDU session release, according to an embodiment of this disclosure, is illustrated. Figure 10 As shown, SMF and NSACF interact to perform validity checks and updates regarding the number of PDU sessions created. Specifically, this includes the following procedures.

[0212] S1001, the UE sends a PDU session release request to the AMF.

[0213] S1002, AMF sends a PDU session release request message (Nsmf_PDUSession_ReleaseSMContext_Request) to SMF.

[0214] S1003, SMF sends a validity check and update request message (Nnsacf_NumberOfPDUsPerSliceAvailabilityCheckAndUpdate_Request) to the selected NSACF.

[0215] S1004, NSACF performs a check and update of the number of PDU sessions created.

[0216] S1005, NSACF sends a validity check and update response message (Nnsacf_NumberOfPDUsPerSliceAvailabilityCheckAndUpdate_Response) to SMF.

[0217] S1006, SMF sends a PDU session release response message (Nsmf_PDUSession_ReleaseSMContext_Response) to AMF.

[0218] S1007, the AMF sends a PDU session release message to the UE.

[0219] The methods provided in the embodiments of this application above are described from the perspective of a network device. To implement the functions of the methods provided in the embodiments of this application above, the network device may include hardware structures and software modules, implementing the above functions in the form of hardware structures, software modules, or a combination of hardware structures and software modules. One of the above functions can be executed in the form of hardware structures, software modules, or a combination of hardware structures and software modules.

[0220] Corresponding to the NSACF selection methods provided in the above embodiments, this disclosure also provides an NSACF selection device. Since the NSACF selection device provided in this disclosure corresponds to the NSACF selection methods provided in the above embodiments, the implementation of the NSACF selection methods is also applicable to the NSACF selection device provided in this embodiment, and will not be described in detail in this embodiment.

[0221] Figure 11 This is a schematic diagram of the structure of an NSACF selection device 1100 provided in an embodiment of this disclosure.

[0222] like Figure 11As shown, the device 1100 is applied to a first session management function (SMF) and may include a processing module 1101. The processing module 1101 is configured to select an NSACF for a network slice based on NSACF service area information, wherein the selected NSACF is used to monitor the number of creation protocol data unit (PDU) sessions of the network slice.

[0223] According to the NSACF selection apparatus of the present disclosure, the SMF selects an NSACF for a network slice based on the service area information of the NSACF. By considering the service area information of the NSACF when selecting an NSACF, the appropriate NSACF can be selected more accurately and with less signaling and function interaction.

[0224] In some embodiments, the service area information includes one or more of the following: a list of tracking area identifiers; service area information of the SMF; and service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

[0225] In some embodiments, the processing module 1101 is configured to: if an NSACF has been selected for the network slice and the service area information of the NSACF indicates that the selected NSACF can be used for the network slice, maintain the selected NSACF being selected for the network slice.

[0226] In some embodiments, if multiple NSACFs have been selected for the network slice and the service area information of the multiple NSACFs indicates that the multiple selected NSACFs can be used for the network slice, the processing module 1101 selects an NSACF for the network slice from the multiple selected NSACFs.

[0227] In some embodiments, the processing module 1101 selects an NSACF for the network slice from a plurality of selected NSACFs based on the service capabilities of the NSACF; wherein the service capabilities include at least one of the following: a first service capability that supports monitoring the number of registered user equipment (UE) of the network slice, and a second service capability that supports monitoring the number of PDU creation sessions of the network slice.

[0228] In some embodiments, if one or more NSACFs have been selected for the network slice and the service area information of the one or more NSACFs indicates that none of the selected one or more NSACFs should be used for the network slice, the processing module 1101 selects an NSACF that does not belong to the one or more selected NSACFs for the network slice.

[0229] In some embodiments, the processing module 1101 selects an NSACF for the network slice based on the NSACF service area information and the operator service area policy; wherein the operator service area policy includes specific rules specified by the operator for performing NSACF selection based on the service area information.

[0230] In some embodiments, the operator service area policy is pre-configured in at least one of the first SMF and network storage function NRF.

[0231] In some embodiments, the processing module 1101 selects an NSACF for the network slice from the registered NSACFs of the NRF, wherein the NRF stores configuration information of the registered NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

[0232] In some embodiments, the processing module 1101 selects an NSACF for the network slice from the pre-configured NSACFs of the first SMF, wherein the first SMF stores configuration information of the pre-configured NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

[0233] In some embodiments, such as Figure 12 As shown, the apparatus 1100 further includes a transceiver module 1102. The transceiver module 1102 is configured to receive a PDU session creation request or a PDU session update request from a UE via an Access and Mobility Management Function (AMF), wherein the PDU session creation request and the PDU session update request carry S-NSSAIs. The processing module 1101 is configured to select an NSACF for the network slice after the transceiver module receives the PDU session creation request or the PDU session update request.

[0234] In some embodiments, the transceiver module 1102 is further configured to: send a session count validity check and update request to a selected NSACF, the session count validity check and update request including the S-NSSAIs and an update flag, wherein the update flag indicates an increase in the number of PDU sessions created; and receive a session count validity check and update response message from the selected NSACF; and the processing module 1101 is further configured to perform PDU session creation or PDU session update based on the session count validity check and update response message.

[0235] In some embodiments, the processing module 1101 is further configured to: if the session count validity check and update response message indicates that the validity check is successful, execute the PDU session creation process or the PDU session update process, and after completing the PDU session creation or PDU session update, instruct the transceiver module 1102 to return a session creation acceptance message or a session update acceptance message to the UE via the AMF; and if the session count validity check and update response message indicates that the validity check fails, instruct the transceiver module 1102 to return a session creation rejection message or a session update rejection message to the UE via the AMF.

[0236] In some embodiments, the transceiver module 1102 is configured to receive a PDU session release request from a UE via an AMF, wherein the PDU session release request carries S-NSSAIs; in response to the PDU session release request, send a session count validity check and update request to an NSACF selected for the network slice identified by the S-NSSAIs, the session count validity check and update request including the NSSAIs and an update flag, wherein the update flag indicates a reduction in the number of PDU sessions created; and receive a session count validity check and update response message from the selected NSACF; wherein the processing module 1101 is configured to release the PDU session according to the session count validity check and update response message.

[0237] Please see Figure 13 , Figure 13 This is a schematic diagram of the structure of a communication device 1300 provided in an embodiment of this application. The communication device 1300 can be a network device, a user equipment, a chip, chip system, or processor that supports the network device in implementing the above methods, or a chip, chip system, or processor that supports a terminal device in implementing the above methods. This device can be used to implement the methods described in the above method embodiments; for details, please refer to the descriptions in the above method embodiments.

[0238] The communication device 1300 may include one or more processors 1301. The processor 1301 may be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the communication device (e.g., base station, baseband chip, terminal equipment, terminal equipment chip, DU or CU, etc.), execute computer programs, and process data from the computer programs.

[0239] Optionally, the communication device 1300 may further include one or more memories 1302, which may store a computer program 1304. The processor 1301 executes the computer program 1304 to cause the communication device 1300 to perform the methods described in the above method embodiments. Optionally, the memory 1302 may also store data. The communication device 1300 and the memory 1302 may be provided separately or integrated together.

[0240] Optionally, the communication device 1300 may also include a transceiver 1305 and an antenna 1306. The transceiver 1305 may be referred to as a transceiver unit, transceiver, or transceiver circuit, etc., and is used to implement the transmission and reception functions. The transceiver 1305 may include a receiver and a transmitter. The receiver may be referred to as a receiver or receiving circuit, etc., and is used to implement the receiving function; the transmitter may be referred to as a transmitter or transmitting circuit, etc., and is used to implement the transmitting function.

[0241] Optionally, the communication device 1300 may further include one or more interface circuits 1307. The interface circuits 1307 are used to receive code instructions and transmit them to the processor 1301. The processor 1301 executes the code instructions to cause the communication device 1300 to perform the methods described in the above method embodiments.

[0242] Communication device 1300 is a network device: processor 1301 is used to execute Figure 1 Step S101 in Figure 2 Steps S201 and S2011-S2013 in the process Figure 3 Steps S301 and S3011 in the process Figure 4 Steps S401 and S4011-S4012 in the process Figure 5 Steps S501 and S5011 in the process Figure 6 Steps S601, S603, and S6031 in the process Figure 7 Steps S701 and S704 are performed by transceiver 1305. Figure 6 Steps S602-S603 and S6031-S6032 in the process Figure 7 Steps S702-S704 in the process.

[0243] In one implementation, the processor 1301 may include a transceiver for implementing receive and transmit functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit can be used for reading and writing code / data, or it can be used for transmitting or relaying signals.

[0244] In one implementation, processor 1301 may store computer program 1303, which runs on processor 1301 and causes communication device 1300 to perform the methods described in the above method embodiments. Computer program 1303 may be embedded in processor 1301, in which case processor 1301 may be implemented in hardware.

[0245] In one implementation, the communication device 1300 may include circuitry capable of performing the functions of transmitting, receiving, or communicating as described in the foregoing method embodiments. The processor and transceiver described in this application can be implemented on integrated circuits (ICs), analog ICs, radio frequency integrated circuits (RFICs), mixed-signal ICs, application-specific integrated circuits (ASICs), printed circuit boards (PCBs), electronic devices, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal-oxide-semiconductor (CMOS), n-metal-oxide-semiconductor (NMOS), p-type metal-oxide-semiconductor (PMOS), bipolar junction transistors (BJTs), bipolar CMOS (BiCMOS), silicon-germanium (SiGe), gallium arsenide (GaAs), etc.

[0246] The communication device described in the above embodiments may be a network device or a terminal device (such as the first terminal device in the foregoing method embodiments), but the scope of the communication device described in this application is not limited thereto, and the structure of the communication device may vary. Figure 13 The communication device may be a standalone device or part of a larger device. For example, the communication device may be:

[0247] (1) Independent integrated circuit IC, or chip, or chip system or subsystem;

[0248] (2) A collection of one or more ICs, optionally including storage components for storing data and computer programs;

[0249] (3) ASIC, such as modem;

[0250] (4) Modules that can be embedded in other devices;

[0251] (5) Receivers, terminal equipment, smart terminal equipment, cellular phones, wireless equipment, handheld devices, mobile units, vehicle-mounted equipment, network equipment, cloud equipment, artificial intelligence equipment, etc.

[0252] (6) Others, etc.

[0253] For cases where the communication device can be a chip or a chip system, please refer to [link / reference]. Figure 14 The diagram shows the structure of the chip. Figure 14 The chip shown includes a processor 1401 and an interface 1402. There can be one or more processors 1401, and multiple interfaces 1402.

[0254] In the case where the chip is used to implement the functions of the network device in the embodiments of this application: the processor 1401 is used to execute... Figure 1 Step S101 in Figure 2 Steps S201 and S2011-S2013 in the process Figure 3 Steps S301 and S3011 in the process Figure 4 Steps S401 and S4011-S4012 in the process Figure 5 Steps S501 and S5011 in the process Figure 6 Steps S601, S603, and S6031 in the process Figure 7 Steps S701 and S704 are described in the text; interface 1402 is used to execute... Figure 6 Steps S602-S603 and S6031-S6032 in the process Figure 7 Steps S702-S704 in the process.

[0255] Optionally, the chip also includes a memory 1403 for storing necessary computer programs and data.

[0256] Those skilled in the art will also understand that the various illustrative logical blocks and steps listed in the embodiments of this application can be implemented by electronic hardware, computer software, or a combination of both. Whether such functionality is implemented through hardware or software depends on the specific application and the overall system design requirements. Those skilled in the art can implement the described functionality using various methods for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of this application.

[0257] This application also provides a readable storage medium having instructions stored thereon that, when executed by a computer, implement the functions of any of the above method embodiments.

[0258] This application also provides a computer program product that, when executed by a computer, implements the functions of any of the above method embodiments.

[0259] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer programs. When the computer program is loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer program can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program can be transferred from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0260] Those skilled in the art will understand that the various numerical designations such as "first," "second," etc., involved in this application are merely for the convenience of description and are not intended to limit the scope of the embodiments of this application, nor do they indicate the order of sequence.

[0261] At least one in this application can also be described as one or more, and multiple can be two, three, four or more, and this application does not impose any limitation. In the embodiments of this application, for a technical feature, the technical features in that technical feature are distinguished by "first", "second", "third", "A", "B", "C" and "D", and there is no order or size among the technical features described by "first", "second", "third", "A", "B", "C" and "D".

[0262] As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, device, and / or apparatus (e.g., disk, optical disk, memory, programmable logic device (PLD)) used to provide machine instructions and / or data to a programmable processor, including machine-readable media that receive machine instructions as machine-readable signals. The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0263] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as a data server), or computing systems that include middleware components (e.g., an application server), or computing systems that include frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., a communication network). Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0264] Computer systems can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other.

[0265] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0266] Furthermore, it should be understood that the various embodiments described in this application can be implemented individually or in combination with other embodiments, where the scheme allows.

[0267] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0268] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0269] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for selecting a Network Slice Admission Control Function (NSACF), characterized in that, The method is executed by the first session management function (SMF), and the method includes: After receiving a Protocol Data Unit (PDU) session update request from a User Equipment (UE) via the Access and Mobility Management Function (AMF), the NSACF is selected for the network slice based on the NSACF's service area information and the operator's service area policy. The selected NSACF is used to monitor the number of PDU sessions created for the network slice. The NSACF selection for network slices includes: If one or more NSACFs have been selected for the network slice and the service area information of the one or more NSACFs indicates that none of the selected one or more NSACFs should be used for the network slice, select an NSACF that does not belong to the one or more selected NSACFs for the network slice. If multiple NSACFs have been selected for the network slice and the service area information of the multiple NSACFs indicates that the selected multiple NSACFs can be used for the network slice, an NSACF is selected for the network slice from the multiple selected NSACFs based on the service capabilities of the NSACFs; wherein the service capabilities include at least one of the following: The first service capability supports monitoring the number of registered user equipment (UEs) in the network slice, and A second service capability supports monitoring the number of PDU sessions created in the network slice; The operator service area policy includes specific rules formulated by the operator to perform NSACF selection based on the service area information. The operator service area policy includes the tracking area identifier (TAI) list, the service area information of the SMF, and the policy priority of the service area information of one or more user plane function (UPF) controlled by the SMF. The operator service area policy also includes at least one of the following: Prioritize each NSACF that has the service capability to support monitoring the number of PDU sessions created for network slices; Request the location information of the UEs of the service that are monitoring the number of PDU sessions created in the network slice; Request the registration tracking area information of the UE that monitors the number of PDU sessions created for the network slice.

2. The method as described in claim 1, characterized in that, The service area information includes one or more of the following: List of tracking area identifiers; SMF's service area information; Service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

3. The method as described in claim 1 or 2, characterized in that, The selection of NSACF for network slices includes: If an NSACF has been selected for the network slice and the service area information of the NSACF indicates that the selected NSACF can be used for the network slice, the selected NSACF is maintained as the selected NSACF for the network slice.

4. The method as described in claim 1, characterized in that, The operator service area policy is pre-configured in at least one of the first SMF and network storage function NRF.

5. The method according to any one of claims 1, 2, and 4, characterized in that, The selection of NSACF for network slices includes: Select an NSACF for the network slice from the registered NSACFs in the NRF, wherein the NRF stores configuration information of the registered NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

6. The method according to any one of claims 1, 2, and 4, characterized in that, The selection of NSACF for network slices includes: The network slice is selected from the pre-configured NSACFs of the first SMF, wherein the first SMF stores the configuration information of the pre-configured NSACFs, and the configuration information includes network slice selection assistance information S-NSSAIs and service area information of registered NSACFs.

7. The method as described in claim 1, characterized in that, After selecting an NSACF for the network slice, the method further includes: Send a session count validity check and update request to the selected NSACF. The session count validity check and update request includes S-NSSAIs and an update flag, wherein the update flag indicates an increase in the number of PDU sessions created; and Receive session count validity check and update response messages from the selected NSACF, and perform PDU session updates based on the session count validity check and update response messages.

8. The method as described in claim 7, characterized in that, The step of updating the PDU session based on the session validity check and update response message includes: If the session count validity check and update response message indicate that the validity check was successful, the PDU session update procedure is executed, and after the PDU session update is completed, a session update acceptance message is returned to the UE via the AMF; and If the session count validity check and update response message indicates that the validity check has failed, a session update rejection message is returned to the UE via the AMF.

9. The method as described in claim 1, characterized in that, Also includes: The PDU session release request is received from the UE via the AMF, wherein the PDU session release request carries S-NSSAIs; In response to the PDU session release request, a session count validity check and update request is sent to the NSACF selected for the network slice identified by the S-NSSAIs. The session count validity check and update request includes the S-NSSAIs and an update flag, wherein the update flag indicates a reduction in the number of PDU sessions created; and Receive session count validity check and update response messages from the selected NSACF, and release PDU sessions based on the session count validity check and update response messages.

10. A selection device for a Network Slice Admission Control Function (NSACF), characterized in that, The apparatus is used in a first session management function (SMF), and the apparatus includes: The processing module is configured to select an NSACF for a network slice based on the NSACF's service area information and the operator's service area policy after receiving a Protocol Data Unit (PDU) session update request from a User Equipment (UE) via the Access and Mobility Management Function (AMF). The selected NSACF is used to monitor the number of PDU sessions created for the network slice. The NSACF selection for network slices includes: If one or more NSACFs have been selected for the network slice and the service area information of the one or more NSACFs indicates that none of the selected one or more NSACFs should be used for the network slice, select an NSACF that does not belong to the one or more selected NSACFs for the network slice. If multiple NSACFs have been selected for the network slice and the service area information of the multiple NSACFs indicates that the selected multiple NSACFs can be used for the network slice, an NSACF is selected for the network slice from the multiple selected NSACFs based on the service capabilities of the NSACFs; wherein the service capabilities include at least one of the following: The first service capability supports monitoring the number of registered user equipment (UEs) in the network slice, and A second service capability supports monitoring the number of PDU sessions created in the network slice; The operator service area policy includes specific rules formulated by the operator to perform NSACF selection based on the service area information. The operator service area policy includes the tracking area identifier (TAI) list, the service area information of the SMF, and the policy priority of the service area information of one or more user plane function (UPF) controlled by the SMF. The operator service area policy also includes at least one of the following: Prioritize each NSACF that has the service capability to support monitoring the number of PDU sessions created for network slices; Request the location information of the UEs of the service that are monitoring the number of PDU sessions created in the network slice; Request the registration tracking area information of the UE that monitors the number of PDU sessions created for the network slice.

11. The apparatus as claimed in claim 10, characterized in that, The service area information includes one or more of the following: List of tracking area identifiers; SMF's service area information; Service area information of one or more User Plane Functions (UPFs) controlled by the SMF.

12. The apparatus as claimed in claim 10 or 11, characterized in that, The processing module is configured as follows: If an NSACF has been selected for the network slice and the service area information of the NSACF indicates that the selected NSACF can be used for the network slice, the selected NSACF is maintained as the selected NSACF for the network slice.

13. The apparatus as claimed in claim 10, characterized in that, The operator service area policy is pre-configured in at least one of the first SMF and network storage function NRF.

14. The apparatus as claimed in any one of claims 10, 11, and 13, characterized in that, The processing module is configured as follows: Select an NSACF for the network slice from the registered NSACFs in the NRF, wherein the NRF stores configuration information of the registered NSACFs, the configuration information including network slice selection assistance information S-NSSAIs and service area information of the registered NSACFs.

15. The apparatus as claimed in any one of claims 10, 11, and 13, characterized in that, The processing module is configured as follows: The network slice is selected from the pre-configured NSACFs of the first SMF, wherein the first SMF stores the configuration information of the pre-configured NSACFs, and the configuration information includes network slice selection assistance information S-NSSAIs and service area information of registered NSACFs.

16. The apparatus as claimed in claim 10, characterized in that, The device also includes a transceiver module. The transceiver module is configured to send a session count validity check and update request to the selected NSACF, the session count validity check and update request including S-NSSAIs and an update flag, wherein the update flag indicates an increase in the number of PDU sessions created; and receive session count validity check and update response messages from the selected NSACF; and The processing module is also configured to perform PDU session updates based on the session validity check and update response message.

17. The apparatus as claimed in claim 16, characterized in that, The processing module is configured as follows: If the session validity check and update response message indicate that the validity check is successful, the PDU session update procedure is executed, and after the PDU session update is completed, the transceiver module is instructed to return a session update acceptance message to the UE via the AMF; as well as If the session count validity check and update response message indicates that the validity check has failed, the transceiver module is instructed to return a session update rejection message to the UE via the AMF.

18. The apparatus as claimed in claim 10, characterized in that, Also includes: The transceiver module is configured to receive a PDU session release request from a UE via an AMF, wherein the PDU session release request carries S-NSSAIs; in response to the PDU session release request, send a session count validity check and update request to an NSACF selected for the network slice identified by the S-NSSAIs, the session count validity check and update request including the S-NSSAIs and an update flag, wherein the update flag indicates a reduction in the number of PDU sessions created; and receive a session count validity check and update response message from the selected NSACF. The processing module is configured to release PDU sessions based on the validity check of the session count and the update response message.

19. A communication device, wherein, include: transceiver; Memory; A processor, connected to both the transceiver and the memory, is configured to control the wireless signal transmission and reception of the transceiver by executing computer-executable instructions on the memory, and to implement the method described in any one of claims 1-9.

20. A computer storage medium, wherein, The computer storage medium stores computer-executable instructions; when the computer-executable instructions are executed by a processor, they can implement the method described in any one of claims 1-9.

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