Method, apparatus and computer program

Abstract

There is provided an apparatus comprising means for: sending an identifier of a network slice and an identifier of at least one alternative network slice to a network repository function (NRF); receiving, from the NRF, information identifying at least one of: a first set of one or more SMFs, a supporting network slice, and at least one alternative network slice; a second set of one or more SMFs supporting network slicing; a third set of one or more SMFs supporting at least one alternative network slice; wherein the component is further configured to select an SMF for a protocol data unit (PDU) session based on the information.

Description

Technical Field

[0001] Various example embodiments of the present disclosure relate to methods, apparatus, systems, and computer programs for communication networks. Some examples may be used to select an appropriate network function for a data session in a communication network. Background Art

[0002] A communication network can be seen as a facility that enables communication between two or more communication devices, or provides access of communication devices to a data network. A mobile or wireless communication network is an example of a communication network. Communication devices may be served by application servers.

[0003] Such communication networks operate according to standards such as those provided by 3GPP (3rd Generation Partnership Project) or ETSI (European Telecommunications Standards Institute).An example of a standard is the so-called 5G (fifth generation) standard provided by 3GPP. Summary of the invention

[0004] Some example embodiments of the present disclosure will be described with respect to certain aspects. These aspects are not intended to indicate the key or essential features of the embodiments of the present disclosure, nor are they intended to be used to limit the scope thereof. In view of the present disclosure, other features, aspects and elements will be apparent to those skilled in the art.

[0005] A device comprising a component for: sending an identifier of a network slice and an identifier of at least one alternative network slice to a network repository function (NRF); receiving information from the NRF for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; and a third set of one or more SMFs that support at least one alternative network slice; wherein the component is also used to: select an SMF for a protocol data unit (PDU) session based on the information.

[0006] According to some examples, selecting the SMF for the PDU session based on the information includes: when the information indicates at least one SMF in the first set, selecting the SMF in the first set for the PDU session.

[0007] According to some examples, selecting an SMF for a PDU session based on information includes: when the information does not indicate an SMF in the first set or the second set but indicates at least one SMF in the third set, selecting an SMF from the third set, wherein the component is also configured to execute: sending a PDU session establishment request to the selected SMF to establish the PDU session.

[0008] According to some examples, the information includes: load information for SMFs in at least one of the first set, the second set, and the third set, and wherein selecting the SMF for a protocol data unit (PDU) session is based on the load information.

[0009] According to some examples, the apparatus is located in a home public land mobile network (PLMN) and the NRF is located in a virtual PLMN.

[0010] In some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are sent to the NRF in a network function discovery request message.

[0011] According to some examples, the component is used to: send an identifier of a network slice and an identifier of at least one alternative network slice to a network slice selection function (NSSF); and receive information from the NSSF that identifies the NRF as serving both the network slice and the alternative network slice.

[0012] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are sent to the NSSF in a network slice selection request message.

[0013] According to some examples, at least one alternative network slice includes two or more alternative network slices.

[0014] According to some examples, sending an identifier of a network slice and an identifier of at least one alternative network slice to an NRF includes sending an identifier of the network slice and an identifier of at least one alternative network slice in an Nnrf_NFDiscovery_Request service operation.

[0015] According to one aspect, a device is provided, comprising at least one processor and at least one memory, wherein the at least one memory stores instructions which, when executed by the at least one processor, cause the device to at least: send an identifier of a network slice and an identifier of at least one alternative network slice to an NRF; receive information from the NRF for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; and a third set of one or more SMFs that support at least one alternative network slice; wherein the at least one processor is configured to cause the device to: select an SMF for a PDU session based on the information.

[0016] According to some examples, selecting the SMF for the PDU session based on the information includes: when the information indicates at least one SMF in the first set, selecting the SMF in the first set for the PDU session.

[0017] According to some examples, based on the information, selecting an SMF for a PDU session includes: when the information does not indicate an SMF in the first set or the second set but indicates at least one SMF in the third set, selecting an SMF from the third set, wherein at least one processor is configured to cause the device to: send a PDU session establishment request to the selected SMF to establish the PDU session.

[0018] According to some examples, the information includes: load information for SMFs in at least one of the first set, the second set, and the third set, and wherein selecting the SMF for a protocol data unit (PDU) session is based on the load information.

[0019] According to some examples, the apparatus is located in a home public land mobile network (PLMN) and the NRF is located in a virtual PLMN.

[0020] In some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are sent to the NRF in a network function discovery request message.

[0021] According to some examples, at least one processor is configured to cause the device to: send an identifier of a network slice and an identifier of at least one alternative network slice to the NSSF; and receive information from the NSSF identifying the NRF as serving both the network slice and the alternative network slice.

[0022] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are sent to the NSSF in a network slice selection request message.

[0023] According to some examples, at least one alternative network slice includes two or more alternative network slices.

[0024] According to some examples, sending an identifier of a network slice and an identifier of at least one alternative network slice to an NRF includes sending an identifier of the network slice and an identifier of at least one alternative network slice in an Nnrf_NFDiscovery_Request service operation.

[0025] According to one aspect, a method is provided, comprising: sending an identifier of a network slice and an identifier of at least one alternative network slice to an NRF; receiving information from the NRF for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; and a third set of one or more SMFs that support at least one alternative network slice; wherein the method comprises: selecting an SMF for a PDU session based on the information.

[0026] According to some examples, selecting the SMF for the PDU session based on the information includes: when the information indicates at least one SMF in the first set, selecting the SMF in the first set for the PDU session.

[0027] According to some examples, based on the information, selecting an SMF for a PDU session includes: when the information does not indicate an SMF in the first set or the second set but indicates at least one SMF in the third set, selecting an SMF from the third set, wherein the method includes: sending a PDU session establishment request to the selected SMF to establish the PDU session.

[0028] According to some examples, the information includes: load information for SMFs in at least one of the first set, the second set, and the third set, and wherein selecting the SMF for a protocol data unit (PDU) session is based on the load information.

[0029] In some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are sent to the NRF in a network function discovery request message.

[0030] According to some examples, the method includes: sending an identifier of a network slice and an identifier of at least one alternative network slice to the NSSF; and receiving information from the NSSF identifying the NRF as serving both the network slice and the alternative network slice.

[0031] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are sent to the NSSF in a network slice selection request message.

[0032] According to some examples, at least one alternative network slice includes two or more alternative network slices.

[0033] According to some examples, sending an identifier of a network slice and an identifier of at least one alternative network slice to an NRF includes sending an identifier of the network slice and an identifier of at least one alternative network slice in an Nnrf_NFDiscovery_Request service operation.

[0034] According to one aspect, a computer-readable medium is provided, comprising instructions, which, when executed by an apparatus, cause the apparatus to perform at least the following items: sending an identifier of a network slice and an identifier of at least one alternative network slice to an NRF; receiving information from the NRF for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; a third set of one or more SMFs that support at least one alternative network slice; and selecting an SMF for a PDU session based on the information.

[0035] According to one aspect, a device is provided, comprising a component for: receiving an identifier of a network slice and an identifier of at least one alternative network slice from an AMF; determining information for identifying at least one of: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; a third set of one or more SMFs that support at least one alternative network slice; wherein the component is also used to: send information to the AMF.

[0036] According to some examples, the component is used to: receive a list of slice identifiers and an indication of a slice identifier sharing user plane function (UPF) from the SMF in the Nnrf_NFManagement_NFRegister service operation; determine that a network slice and at least one alternative network slice share a UPF; and send an indication that network slices at at least one alternative network slice share the same UPF.

[0037] According to some examples, the information also includes: load information for SMFs in at least one of the first set, the second set, and the third set.

[0038] According to some examples, the apparatus is located in a virtual public land mobile network (PLMN) and the AMF is located in a home PLMN.

[0039] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are received in a network function discovery request message.

[0040] According to one aspect, a method is provided, comprising: receiving an identifier of a network slice and an identifier of at least one alternative network slice from an AMF; determining information for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; and a third set of one or more SMFs that support at least one alternative network slice; wherein the method comprises: sending information to the AMF.

[0041] According to some examples, the method includes: in the Nnrf_NFManagement_NFRegister service operation, receiving a list of slice identifiers and an indication that the slice identifiers share a UPF from the SMF; determining that a network slice and at least one alternative network slice share a UPF; and sending an indication that the network slices at at least one alternative network slice share the same UPF.

[0042] According to some examples, the information also includes: load information for SMFs in at least one of the first set, the second set, and the third set.

[0043] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are received in a network function discovery request message.

[0044] According to one aspect, a computer readable medium is provided, the medium comprising instructions, which when executed by an apparatus causes the apparatus to perform at least the following:

[0045] According to one aspect, a device is provided, comprising at least one processor and at least one memory, the at least one memory storing instructions, which, when executed by the at least one processor, causes the device to at least: receive an identifier of a network slice and an identifier of at least one alternative network slice from an AMF; determine information for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; and a third set of one or more SMFs that support at least one alternative network slice; wherein the at least one processor can be configured to cause the device to: send information to the AMF.

[0046] According to some examples, at least one processor may be configured to cause the device to: receive a list of slice identifiers and an indication that the slice identifiers share a UPF from the SMF in an Nnrf_NFManagement_NFRegister service operation; determine that a network slice and at least one alternative network slice share a UPF; and send an indication that the network slices at at least one alternative network slice share the same UPF.

[0047] According to some examples, the information also includes: load information for SMFs in at least one of the first set, the second set, and the third set.

[0048] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are received in a network function discovery request message.

[0049] According to one aspect, a computer-readable medium is provided, comprising instructions, which, when executed by an apparatus, cause the apparatus to perform at least the following items: receive an identifier of a network slice and an identifier of at least one alternative network slice from an AMF; determine information for identifying at least one of the following items: a first set of one or more SMFs that support both the network slice and at least one alternative network slice; a second set of one or more SMFs that support the network slice; a third set of one or more SMFs that support at least one alternative network slice; and send information to the AMF.

[0050] According to one aspect, an apparatus is provided, comprising means for: receiving, from an AMF, an identifier of a network slice, and an identifier of at least one alternative network slice;

[0051] Determine information identifying the NRF that serves both the network slice and the alternative network slice; send information to the AMF.

[0052] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are received from the AMF in a network slice selection request message.

[0053] According to one aspect, a method is provided, comprising: receiving, from an AMF, an identifier of a network slice, and an identifier of at least one candidate network slice;

[0054] Determine information identifying the NRF that serves both the network slice and the alternative network slice; send information to the AMF.

[0055] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are received from the AMF in a network slice selection request message.

[0056] According to one aspect, a device is provided, comprising at least one processor and at least one memory, wherein the at least one memory stores instructions which, when executed by the at least one processor, cause the device to at least: receive an identifier of a network slice and an identifier of at least one alternative network slice from an AMF; determine information identifying an NRF serving both the network slice and the alternative network slice; and send information to the AMF.

[0057] According to some examples, an identifier of a network slice, and an identifier of at least one alternative network slice are received from the AMF in a network slice selection request message.

[0058] According to one aspect, a non-transitory computer-readable medium is provided, comprising program instructions, which, when executed by an apparatus, cause the apparatus to at least perform a method according to any of the preceding aspects.

[0059] In the above, many different embodiments have been described. It should be understood that further embodiments can be provided by combining any two or more of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Some example embodiments will now be described, by way of non-limiting and illustrative examples only, with reference to the accompanying drawings, in which:

[0061] Figure 1 A representation of a fifth generation communication system is shown;

[0062] Figure 2 An example SMF selection process is shown;

[0063] Figure 3 An example SMF selection process is shown;

[0064] Figure 4 An example SMF selection process is shown;

[0065] Figure 5 An example SMF selection process is shown;

[0066] Figure 6 An example method is shown;

[0067] Figure 7 An example method is shown;

[0068] Figure 8 According to some example embodiments, Figure 1 Representation of the devices of the communication system;

[0069] Fig. 9 shows representations of apparatus according to some example embodiments;

[0070] Fig.10 A schematic representation of a non-volatile storage medium storing instructions which, when executed by a processor, allow the processor to perform one or more steps of the methods disclosed herein; and

[0071] Fig.11 Two schematic representations of non-volatile storage media are shown. DETAILED DESCRIPTION

[0072] Network slicing is a technology that allows multiple virtual networks to be created on top of a single physical infrastructure, where each virtual network (often referred to as a network slice) is optimized for specific use cases, applications or customer requirements. Network slicing enables efficient and flexible allocation of network resources, providing the necessary performance and features tailored to the needs of different services and applications.

[0073] A network slice can be identified by a single network slice selection assistance information (S-NSSAI), which consists of a slice / service type (SST) and a slice distinguisher (SD). Including SD in S-NSSAI is optional. A set of one or more S-NSSAI is called network slice selection assistance information (NSSAI).

[0074] Network slice replacement is a feature of the 5G communication system that addresses the situation when a specific S-NSSAI becomes unavailable or congested. In this case, the network slice replacement function allows the original network slice identified by the S-NSSAI to be replaced with an alternative network slice identified by the S-NSSAI. This provides continuous service availability and performance for the user or user equipment. When the 5GS supports the network slice replacement feature, the selection of the serving network function (e.g., SMF) replaces the network slice selection assistance information (S-NSSAI) with an alternative S-NSSAI. The SMF can be responsible for the management of user plane data within a specific network slice, and the SMF can participate in the process of selection and replacement of network slices.

[0075] Network slice replacement using alternative S-NSSAI is described in 3GPPP TS23.502 clause 4.3.2.2.3.2. In the current network slice replacement method, if the SMF that originally served the protocol data unit (PDU) session in the network slice identified by the first S-NSSAI does not support the alternative network slice identified by the alternative S-NSSAI for network slice replacement, a new SMF is selected based on the "alternative S-NSSAI" and a new PDU session is established by the new SMF. The establishment of a new PDU session and moving the service to the new PDU session may cause service discontinuity. The examples described in this article reduce such service discontinuity.

[0076] In the following, various exemplary embodiments are explained with reference to a communication device capable of communicating with a communication system. Before explaining the embodiments of the method and apparatus of the present disclosure in detail, a fifth generation communication system (5GS), its access network and core network (5GC), and a communication device are explained with reference to Figure 1 is briefly explained.

[0077] Figure 1 A schematic diagram of a 5G communication system (5GS) is shown. The 5GS may include a user equipment (UE), an access network (such as a 5G radio access network (5G-RAN) or a next generation radio access network (NG-RAN), a 5G core network (5GC), and one or more application functions. The application functions may be deployed in the 5GS as trusted application functions, or may be deployed or hosted on one or more application servers of a data network. Such application functions are non-trusted application functions. The 5GS connects the UE to the data network, the access network, and the 5GC (e.g., the UPF of the 5GC).

[0078] 5G-RAN may include one or more radio access nodes, such as gNodeB (GNB). gNB may include one or more gNodeB (GNB) distributed units connected to one or more gNodeB (GNB) centralized units.

[0079] 5GC may include the following network functions: network slice selection function (NSSF); network exposure function; network repository function (NRF); policy control function (PCF); unified data management (UDM); application function (AF); authentication server function (AUSF); access and mobility management function (AMF); and session management function (SMF), as well as user plane function (UPF). Figure 1 Also shown are the various interfaces (N1, N2, etc.) that may be implemented between the various elements of the system.

[0080] Figure 2 An example process is shown involving a first network function 202, a second network function 204, and a third network function 206. In some examples, each of the network functions 202, 204, and 206 may be part of the same PLMN serving the UE.

[0081] According to some examples, the first network function 202 may include an AMF, the second network function 204 may include an NSSF, and the third network function 206 may include an NRF. For ease of reference, AMF 202, NSSF 204, and NRF 206 are mentioned below, but it should be understood that other suitable network functions having the functions of AMF 202, NSSF 202, and NRF 204 may participate. Figure 2 The process shown in .

[0082] According to some examples, the SMF may provide a list of slice identifier lists and an indication of a slice identifier sharing user plane function (UPF) to the NRF 206 in the Nnrf_NFManagement_NFRegister service operation. The NRF may then use this to determine that the network slice and at least one alternative network slice share the UPF.

[0083] At 201, AMF 202 sends a request for a network slice to NSSF 204. The request may include information indicating a network slice identifier requested by the UE (e.g., S-NSSAI) and at least one alternative network slice identifier for the UE (e.g., alternative S-NSSAI). The network slice identifier (also referred to as a slice identifier) ​​requested by the UE in the request may be considered a "primary" slice identifier. In some examples, the primary slice identifier may include an identifier of a network slice that is already serving the UE. NSSF 204 may be part of a PLMN serving the UE. According to some examples, the request may be for a network slice for a specific PDU session. According to some examples, at least one alternative slice identifier may include two or more slice identifiers of corresponding alternative network slices.

[0084] The request sent at 201 may include at least one of the following: an identifier of a PLMN ("PLMN ID"), a subscription permanent identifier (SUPI) of a UE; a tracking area identity (TAI) of a UE. The request sent at 201 may include an indication that the request is within the process of PDU session establishment in non-roaming or roaming with local breakout scenario.

[0085] The request sent at 201 may include an Nnssf_NSSelection_Get request that additionally includes information indicating an alternative S-NSSAI.

[0086] In response to the request, at 203, NSSF 204 may provide information indicating an NRF 206 that supports both the primary network slice identified by the S-NSSAI (the serving network slice or the requested network slice if the network was requested at 201 but is not yet acting as a serving network slice) and at least one alternative network slice identified by (multiple) S-NSSAIs. The information indicating the NRF 206 may include an identifier of the NRF 206 (e.g., a uniform resource identifier (URI) or an IP address of the NRF 206).

[0087] The response sent at 203 may include a Nnssf_NSSelection_Get response. The response set at 203 may include a network slice instance (NSI) identifier (ID).

[0088] In some examples, AMF 202 may already know an appropriate NRF (e.g., NRF 206), which can be used to select NF / service within the corresponding network slice instance based on the configuration of AMF 202 (e.g., the configuration of AMF 202 by the network operator), or based on the network slice selection information received when the UE registers to the PLMN. In such an example, 201 and 203 can be skipped, and the process can start at 205.

[0089] At 205, AMF 202 sends a request to NRF 206 to discover SMFs. In some embodiments, the request includes at least one alternative S-NSSAI to discover SMFs that support at least one alternative S-NSSAI. The request also includes the requested (primary) S-NSSAI to be discovered. The request may include Nnrf_NFDiscovery_Request.

[0090] At 207, the NRF 206 identifies SMFs that meet the following conditions:

[0091] A) supporting both a primary S-NSSAI and at least one alternative S-NSSAI;

[0092] B) Provide support for only the primary S-NSSAI;

[0093] C) Provides support for only the alternative S-NSSAI.

[0094] At 207, the NRF 206 then sends information to the AMF 202 indicating the SMFs (if any) that support each of conditions A)-C).

[0095] Based on the information received at 207, AMF 202 may select an SMF for the established PDU session. As a first preference, AMF 202 may select an SMF that satisfies condition A (i.e., an SMF that supports both the primary S-NSSAI and the alternative S-NSSAI). Therefore, if the initial primary S-NSSAI becomes congested or unavailable, the primary network slice identified by the initial primary S-NSSAI can be easily replaced by the selected SMF with the alternative S-NSSAI. This ensures continuity for the established PDU session, because AMF 202 does not have to release the existing PDU session or establish a new PDU session for the alternative network slice, thereby reducing the signaling between AMF 202 and the selected SMF when the primary network slice is unavailable or congested.

[0096] If the AMF 202 does not receive information indicating at least one SMF satisfying condition A) or B) at 207, but receives information indicating at least one SMF satisfying condition C) at 207, the AMF 202 may determine that the primary S-NSSAI is congested or unavailable. The AMF 202 may then select an SMF indicated to satisfy condition C). The AMF 202 may then continue to send a PDU session establishment request to the selected SMF to establish a new PDU session.

[0097] According to some examples, at 207, the NRF may also provide load information of at least some of the SMFs indicated at 207. This information may be used to help the AMF 202 select an appropriate SMF.

[0098] Figure 3 An example of the SMF selection process for a home-routed roaming scenario is shown.

[0099] The virtual PLMN (VPLMN) may include an AMF 302, a virtual NSSF (VNSSF) 304a, and a virtual NRF (vNRF) 306a. The home PLMN (HPLMN) may include a home NRF (hNRF) 306b and a home NSSF (hNSSF) 304b.

[0100] At 311, AMF 302 sends a request for network slice selection to vNSSF 304a. The request may include information indicating the S-NSSAI requested by the UE and at least one alternative S-NSSAI for the UE.

[0101] The request sent at 311 may include at least one of: a PLMN ID of a Subscription Permanent Identifier (SUPI); a Tracking Area Identity (TAI) of the UE.

[0102] The request sent at 311 may include an Nnssf_NSSelection_Get request that additionally includes information indicating an alternative S-NSSAI.

[0103] At 313, vNSSF 304a forwards the request received at 311 to hNSSF 304b.

[0104] At 315, in response to the request received at 313, the hNSSF 304b may provide information indicating the hNRF 306b, which supports both the primary network slice identified by the S-NSSAI (the serving network slice or the requested network slice if the network was requested at 311 but is not yet acting as a serving network slice) and at least one alternative network slice identified by the S-NSSAI. The information indicating the hNRF 306b may include an identifier of the hNRF 306b (e.g., a uniform resource identifier (URI) or an IP address of the hNRF 306b).

[0105] The response sent at 315 may include a Nnssf_NSSelection_Get response. The response set at 315 may include a network slice instance (NSI) ID.

[0106] At 317 , vNSSF 304a may forward the response received at 315 to AMF 302 .

[0107] In some examples, AMF 302 may already know the appropriate hNRF (e.g., hNRF 306b), which can be used to select NF / service within the corresponding network slice instance based on configuration or based on network slice selection information received during registration. In such an example, 311 to 317 can be skipped and the message flow can start at 319.

[0108] At 319, the AMF 302 sends a request to the vNRF 306a and includes at least one alternative S-NSSAI. The request also includes a primary S-NSSAI for the AMF 302. The request may also include information identifying the hNRF 306b. The request may include an Nnrf_NFDiscovery_Request.

[0109] At 321, the vNRF 306q forwards the request received at 319 to the hNRF 306b.

[0110] The hNRF 306b then determines the SMF in the HPLMN that satisfies the following conditions:

[0111] A) supporting both a primary S-NSSAI and at least one alternative S-NSSAI;

[0112] B) Provide support for only the primary S-NSSAI;

[0113] C) Provides support for only the alternative S-NSSAI.

[0114] At 323, the hNRF 306b then sends information to the vNRF 306a indicating the SMFs (if any) that support each of the conditions A) - C).

[0115] At 325, the vNRF 306a then sends information to the AMF 302 indicating the SMFs (if any) that support each of conditions A)-C).

[0116] Based on the information received at 325, the AMF 302 may select an SMF for the established PDU session. As a first preference, the AMF 302 may select an SMF based on satisfying condition A) (i.e., an SMF that supports both the primary S-NSSAI and the alternative S-NSSAI). Therefore, if the initial primary S-NSSAI becomes congested or unavailable, the primary network slice identified by the initial primary S-NSSAI can be easily replaced by the selected SMF with the alternative S-NSSAI. This ensures continuity for the established PDU session because the AMF 302 does not have to release the existing PDU session or establish a new PDU session for the alternative network slice, thereby reducing the signaling between the AMF 302 and the selected SMF when the primary network slice is unavailable or congested.

[0117] If the AMF 302 does not receive information indicating at least one SMF satisfying condition A) or B) at 325, but receives information indicating at least one SMF satisfying condition C) at 307, the AMF 302 may determine that the primary S-NSSAI is congested or unavailable. The AMF 302 may then select an SMF indicated to satisfy condition C). The AMF 302 may then continue to send a PDU session establishment request to the selected SMF to establish a new PDU session.

[0118] According to some examples, at 323, hNRF 306b may also provide load information of at least some of the SMFs indicated at 323. This information may be sent at 325 to help AMF 302 select an appropriate SMF.

[0119] Figure 4 An example message flow for a home-routed roaming scenario is shown.

[0120] A virtual PLMN (VPLMN) may include a virtual AMF (vAMF) 402a and a vNRF 406a. HPLMN may include an hNRF 406b and a local NRF 406c in the HPLMN.

[0121] At 431, vAMF 402a sends a request to vNRF 406a and includes at least one alternative S-NSSAI. The request also includes a primary S-NSSAI for vAMF 402a. The request may include Nnrf_NFDiscovery_Request.

[0122] At 433, the vNRF 306q forwards the request received at 431 to the hNRF 406b.

[0123] The method can then continue via two options 434 and 438 .

[0124] Option 434 includes 435 and 437. At 435, hNRF 406b determines an SMF that satisfies the following conditions:

[0125] A) supporting both a primary S-NSSAI and at least one alternative S-NSSAI;

[0126] B) Provide support for only the primary S-NSSAI;

[0127] C) Provides support for only the alternative S-NSSAI.

[0128] At 435, the hNRF 346b then sends information to the vNRF 406a indicating the SMFs (if any) that support each of conditions A) - C).

[0129] At 437, the vNRF 406a then sends information to the vAMF 402a indicating the SMFs (if any) that support each of conditions A)-C).

[0130] Option 438 includes 439 , 441 , 443 , and 445 .

[0131] At 439, hNRF 406b sends a request to the local NRF in the home PLMN 406c and includes at least one alternative S-NSSAI. The request also includes the primary S-NSSAI for vAMF 402a. The request may include Nnrf_NFDiscovery_Request.

[0132] At 441, the local NRF 406c determines an SMF that satisfies the following conditions:

[0133] A) supporting both a primary S-NSSAI and at least one alternative S-NSSAI;

[0134] B) Provide support for only the primary S-NSSAI;

[0135] C) Provides support for only the alternative S-NSSAI.

[0136] At 441, the local NRF 406c then sends information to the hNRF 406b indicating the SMFs (if any) that support each of the conditions A)-C). At 443, the information is forwarded from the hNRF 406b to the vNRF 406a. At 445, the information is forwarded from the vNRF 406a to the vAMF 402a.

[0137] In another example embodiment, during the PDU session establishment process (before remapping of the alternative S-NSSAI has occurred), neither the UE nor the AMF is aware of the alternative S-NSSAI. In the example, the AMF may use a UE indication of support for the "network slice replacement" feature. The indication may be received during the registration process. For example, the indication may be sent by the UE. Feature support may be included in the 5G Mobility Management (5GMM) core network function information received during the registration process. Upon receiving an indication of support for the "network slice replacement" feature, the AMF may provide a similar indication to the NSSF or NRF, indicating that the UE supports the "network slice replacement" feature. The NSSF / NRF uses this indication and provides an NRF / SMF (if configured by the network operator of the PLMN) that can support both the primary / requested S-NSSAI and its mapped alternative S-NSSAI.

[0138] Figure 5An example SMF selection process is shown for the case where both the UE 500 and the AMF 502 are unaware of the alternative S-NSSAI during the PDU session establishment process (before remapping of the alternative S-NSSAI to the S-NSSAI has occurred at the UE 500 or the AMF 502).

[0139] At 551, UE 500 sends an indication of support for the feature of "network slice replacement" to AMF 502. According to some examples, the indication may be sent during the registration process. According to some examples, the feature support may be included in the indication in the 5G Mobility Management (5GMM) core network capability information received during the registration process.

[0140] After 551, if AMF 502 knows a suitable NRF 506 for the UE that supports the “network slice replacement” feature, AMF 502 may perform 557. However, if AMF 502 does not know a suitable NRF 506 or wants to obtain updated information of NRF 506, then at 553, AMF 502 sends an indication of support of the “network slice replacement” feature of UE 500.

[0141] At 555, NSSF 502 provides an indication (e.g., an identifier) ​​of an NRF (in this example, NRF 506) that can support both the primary / requested S-NSSAI and the alternate S-NSSAI mapped to the primary S-NSSAI. The mapping between the primary S-NSSAI and the alternate S-NSSAI may have been previously performed (e.g., by a network operator).

[0142] At 557, the AMF 502 sends an indication of UE support for the "network slice replacement" feature to the NRF 506. At 557, the AMF 602 may also send an identifier of the primary network slice and an identifier of the alternative network slice.

[0143] At 559, the NRF 506 provides information to the AMF 502 indicating the SMFs that can support both the primary / requested S-NSSAI and the alternative S-NSSAI mapped to the S-NSSAI.

[0144] Figure 6 An example method flow is shown. For example, the method may be performed by an AMF.

[0145] At 600, the method includes sending an identifier of a network slice and an identifier of at least one alternative network slice to an NRF.

[0146] At 602, the method includes: receiving information from the NRF identifying at least one of the following items: a first set of one or more SMFs that support both network slicing and at least one alternative network slice; a second set of one or more SMFs that support network slicing; and a third set of one or more SMFs that support at least one alternative network slice.

[0147] At 604, the method includes selecting an SMF for the PDU session based on the information.

[0148] Figure 7 An example method flow is shown. The method may be performed by, for example, an NRF.

[0149] At 700, the method includes receiving, from an AMF, an identifier of a network slice and an identifier of at least one alternative network slice.

[0150] At 702, the method includes: determining information for identifying at least one of the following items: a first set of one or more SMFs that supports both network slicing and at least one alternative network slice; a second set of one or more SMFs that supports network slicing; and a third set of one or more SMFs that supports at least one alternative network slice.

[0151] At 704, the method includes sending the information to the AMF.

[0152] Figure 8 An example method flow is shown. For example, the method may be performed by NSSF.

[0153] At 800, the method includes receiving, from an AMF, an identifier of a network slice and an identifier of at least one alternative network slice.

[0154] At 802, the method includes determining information identifying an NRF serving both a network slice and an alternative network slice.

[0155] At 804, the method includes sending the information to the AMF.

[0156] Fig. 9 Shows Figure 1900 for one or more network functions. The device 900 may include at least one random access memory (RAM) 811a, at least one read-only memory (ROM) 911b, at least one processor 912, 913, and a network interface 914. At least one processor 912, 913 may be coupled to the RAM 911a and the ROM 911b. At least one processor 912, 913 may be configured to execute appropriate software code 915. The execution of the software code 915 may, for example, cause the device to perform operations for one or more network functions. The software code 915 may be stored in the ROM 911b. The device 900 may be interconnected with another device 900 for controlling other network functions of the 5GC. In some embodiments, one or more network functions of the 5GC are deployed or hosted on the device 900. In an alternative embodiment, two or more functions of the 5GC may share the device 900.

[0157] Fig.10 An example of a communication device 1000 is shown, such as Figure 1 The terminal shown in . The communication device 1000 can be provided by any device capable of sending and receiving radio signals. Non-limiting examples of the communication device 1000 include user equipment, a mobile station (MS) or a mobile device, such as a mobile phone or a so-called "smartphone", a computer provided with a wireless interface card or other wireless interface facilities (e.g., a USB dongle), a personal data assistant (PDA) or tablet computer provided with wireless communication capabilities, a machine type communication (MTC) device, an Internet of Things (IoT) type communication device, or any combination of these, etc. The communication device 1000 may include a transceiver for sending and / or receiving wireless signals, such as radio signals, for example, carrying communications. The communication may be one or more of voice, electronic mail (email), text message, multimedia data, machine data, etc.

[0158] The communication device 1000 may receive wireless signals (eg, radio signals) over the air or radio interface 1007 via appropriate means for receiving, and may transmit wireless signals via appropriate means for transmitting radio signals. Fig.10 1006. The transceiver 1006 may include, for example, a radio portion and an associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device and may include one or more antenna elements. The antenna arrangement may be a multiple-input multiple-output (MIMO) antenna.

[0159] The communication device 1000 may be provided with at least one processor 1001, at least one memory ROM 1002a, at least one RAM 1002b and other possible components 1003 for software and hardware assistance to perform the tasks it is designed to perform, including accessing a network (e.g., Figure 1 The at least one processor 901 is coupled to the RAM 1002b and the ROM 1002a. The at least one processor 1001 may be configured to execute appropriate software code 1008. The software code 1008 may, for example, allow execution of one or more operations of the communication device. The software code 1008 may be stored in the ROM 1002a.

[0160] The processor, ROM, RAM, transceiver and other circuit systems (e.g., modem) of the communication device may be provided on a circuit board, a chipset, or a system on a chip. The circuit board, chipset, or system on a chip is represented by reference numeral 1004. The communication device 1000 may optionally have a user interface, such as a keyboard 1005, a touch screen or a touch pad, a combination thereof, etc. Depending on the type of communication device, one or more of a display, a speaker, and a microphone may be provided optionally.

[0161] Fig.11 A schematic diagram of non-volatile storage media 1100a (e.g., a computer compact disc (CD) or digital versatile disc (DVD)) and 1100b (e.g., a universal serial bus (USB) memory stick) is shown, storing instructions and / or parameters 1102, which, when executed by a processor, allow the processor to perform one or more steps of any method flow described herein.

[0162] It should be understood that the references to various network functions (e.g., AMF, SMF, TNF, etc.) above may include devices that perform at least some functions associated with those network functions. In addition, the device including the network function may include a virtual network function instance of the network function.

[0163] It should be understood that these devices may include or be coupled to other units or modules for transmission and / or reception, such as radio components or radio heads. Although these devices have been described as one entity, different modules and memories may be implemented in one or more physical or logical entities.

[0164] It should be noted that although some embodiments have been described in relation to 5G networks, similar principles may be applied in relation to other networks and communication systems. Thus, although certain embodiments are described above by reference to examples of certain example architectures for wireless networks, technologies, and standards, the embodiments may be applied to any other suitable form of communication system other than those shown and described herein.

[0165] It is also noted herein that while the above describes exemplifying embodiments, there are numerous variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0166] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is connected by “and” or “or”, mean at least any one element, or at least any two or more elements, or at least all elements.

[0167] In general, various embodiments may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects of the present disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device, although the present disclosure is not limited thereto. Although various aspects of the present disclosure may be illustrated and described by block diagrams, flow charts, or using some other graphical representations, it is fully understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof.

[0168] As used herein, the term "circuitry" may refer to one or more or all of the following:

[0169] (a) implemented solely in hardware circuitry (e.g., implemented solely in analog and / or digital circuitry) and

[0170] (b) a combination of hardware circuitry and software such as (where applicable):

[0171] (i) a combination of analog and / or digital hardware circuits and software / firmware and

[0172] (ii) any portion of hardware processor(s) (including digital signal processor(s)) with software, software and memory(s) that work together to enable a device (such as a mobile phone or server) to perform various functions;

[0173] as well as

[0174] (c) Hardware circuit(s) and / or processor(s) (such as microprocessor(s) or portion(s) of microprocessor(s)) that require software (e.g., firmware) to operate, but the software may not be present when the software is not required for operation.

[0175] This definition of circuitry applies to all uses of the term "component" herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (their) accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0176] Embodiments of the present disclosure may be implemented by computer software executable by a data processor of a mobile device (such as in a processor entity), or by hardware, or by a combination of software and hardware. Computer software or programs (also referred to as program products) include software routines, applets and / or macros, which may be stored in a data storage medium readable by any device, and they include program instructions for performing specific tasks. A computer program product may include one or more computer executable components, which are configured to perform an embodiment when the program is run. One or more computer executable components may be at least one software code or a portion thereof.

[0177] In this regard, it should also be noted that any block of the logic flow shown in the figure can represent a program step, or an interconnected logic circuit, block and function, or a combination of a program step and a logic circuit, block and function. The software can be stored on a physical medium, such as a memory chip or a memory block implemented in a processor, a magnetic medium (such as a hard disk or a floppy disk), and an optical medium (such as, for example, a DVD and its data variant CD). A physical medium is a non-transient medium.

[0178] The term "non-transitory" as used herein is a limitation on the medium itself (ie, tangible, as opposed to a signal), not a limitation on the persistence of data storage (eg, RAM vs. ROM).

[0179] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The data processor may be of any type suitable for the local technical environment and may include, as non-limiting examples, one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an FPGA, a gate-level circuit, and a processor based on a multi-core processor architecture.

[0180] Various example embodiments of the present disclosure can be practiced in various components, such as integrated circuit modules. The design of integrated circuits is generally a highly automated process. Complex and powerful software tools can be used to convert a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0181] The scope of protection sought by various exemplary embodiments of the present disclosure is set forth by the independent claims. The exemplary embodiments described in the present disclosure and their features (if any) that do not fall within the scope of the independent claims should be interpreted as examples that help understand the various exemplary embodiments of the present disclosure.

[0182] The foregoing description provides a complete and informative description of various example embodiments of the present disclosure by way of non-limiting and illustrative examples. However, various modifications and adaptations may become apparent to those skilled in the relevant art in view of the above description when read in conjunction with the accompanying drawings and claims. However, all such and similar modifications of the teachings will still fall within the various example embodiments of the present disclosure set forth in the claims. As non-limiting and illustrative examples, there are additional example embodiments, including combinations of one or more example embodiments with any other example embodiments previously discussed.

Claims

1. An apparatus for communication, comprising means for: sending an identifier of the network slice and an identifier of at least one alternative network slice to a network repository function (NRF); Receiving from the NRF information identifying at least one of: a first set of one or more SMFs supporting both the network slice and the at least one alternative network slice; a second set of one or more SMFs supporting the network slice; and a third set of one or more SMFs supporting the at least one alternative network slice; The component is further configured to: select an SMF for a protocol data unit (PDU) session based on the information.

2. The apparatus of claim 1 , wherein the selecting the SMF for the PDU session based on the information comprises: When the information indicates at least one SMF in the first set, an SMF in the first set is selected for the PDU session.

3. The apparatus of claim 1 , wherein the selecting the SMF for the PDU session based on the information comprises: When the information does not indicate an SMF in the first set or the second set but indicates at least one SMF in the third set, selecting an SMF from the third set, wherein the component is further configured to perform: Send a PDU session establishment request to the selected SMF to establish the PDU session.

4. An apparatus according to any preceding claim, wherein the information comprises: Load information for SMFs in at least one of the first set, the second set, and the third set, and wherein the selecting the SMF for the protocol data unit (PDU) session is based on the load information.

5. An apparatus according to any preceding claim, wherein the apparatus is located in a home Public Land Mobile Network (PLMN) and the NRF is located in a virtual PLMN.

6. An apparatus according to any preceding claim, wherein the identifier of the network slice, and the identifier of the at least one alternative network slice are sent to the NRF in a network function discovery request message.

7. An apparatus for communication, comprising means for: receiving, from an access and mobility management function (AMF), an identifier of the network slice and an identifier of at least one alternative network slice; Determining information identifying at least one of: a first set of one or more SMFs that support both the network slice and the at least one alternative network slice; a second set of one or more SMFs that support the network slice; and a third set of one or more SMFs that support the at least one alternative network slice; The component is also used to: send the information to the AMF.

8. The device according to claim 7, wherein the component is used for: In the Nnrf_NFManagement_NFRegister service operation, receiving from the SMF a list of slice identifiers and an indication that the slice identifiers share a user plane function (UPF); Determining that the network slice and the at least one candidate network slice share the UPF; Sending an indication that the network slices at at least one alternative network slice share the same UPF.

9. An apparatus for communication, comprising means for: receiving, from an access and mobility management function (AMF), an identifier of the network slice and an identifier of at least one alternative network slice; determining information identifying a network repository function (NRF) serving both the network slice and the alternative network slice; Send the information to the AMF.

10. The apparatus according to claim 9, wherein the identifier of the network slice and the identifier of the at least one alternative network slice are received from the AMF in a network slice selection request message.

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