Patent ID: 12256322

DETAILED DESCRIPTION

Terms used in the present disclosure are used merely to describe specific embodiments, and may not intend to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as those commonly understood by a person of ordinary skill in the technical field described in the present disclosure. Among the terms used in the present disclosure, terms defined in a general dictionary may be interpreted as having the same or similar meanings as those in the context of the related art, and unless explicitly defined in the present disclosure, may not be interpreted as ideal or excessively formal meanings. In some cases, even terms defined in the present disclosure may not be interpreted to exclude embodiments of the present disclosure.

A hardware-based approach will be described as an example in various embodiments of the present disclosure to be described hereafter. However, various embodiments of the present disclosure include technology which uses both hardware and software, and accordingly various embodiments of the present disclosure do not exclude a software-based approach.

Terms indicating signals, terms indicating channels, terms indicating control information, terms indicating network entities, and terms indicating components of a device used in the following explanation are illustrated for convenience of description. Accordingly, the present disclosure is not limited to the terms to be described, and other terms having the same technical meaning may be used.

In addition, the present disclosure describes various embodiments using terms used in some communication standard (e.g., 3rd generation partnership project (3GPP)), but this is only an example for description. Various embodiments of the present disclosure may be easily modified and applied in other communication systems.

Hereinafter, the present disclosure describes a technique for supporting slice federation between public land mobile network (PLMN) operators in a wireless communication system.

Network equipment evolves to a virtualized network function (NF—may be used interchangeably with a ‘network element’ in the following) by applying virtualization technology due to development of various information technology (IT), and the virtualized NFs may be implemented in software beyond physical restrictions to be installed/operated in various clouds or data centers (DCs). In particular, the NF may be freely scaled, installed or terminated according to service requirements, system capacity, and network load. Since such NFs, which are implemented in software, are basically driven on a physical configuration, for example, specific equipment, it should be noted that the physical configuration is not excluded. Also, the NFs may be implemented simply with a physical configuration, that is, in hardware.

A network slicing technology has been introduced to support various services in these various network structures. The network slicing is a technology which logically configures a network with a set of NFs for supporting a specific service, and separates it from other slices. One terminal may access two or more slices if receiving various services.

FIG.1illustrates a wireless communication system according to various embodiments of the present disclosure.

Referring toFIG.1, a radio access node (RAN)110and a user equipment (UE)120are illustrated, as two of nodes using a radio channel in the wireless communication system. WhileFIG.1illustrates only one RAN110and one UE120, other base stations identical or similar to the RAN station110may be further included. Also,FIG.1illustrates that only one UE120communicates within one RAN110. However, it is apparent that a plurality of UEs may actually communicate within one RAN110.

The RAN110is a network infrastructure for providing radio access to the UE120. The RAN110has coverage defined as a specific geographic region based on a signal transmission distance (not shown inFIG.1). Besides a base station, the RAN110may be referred to as an ‘access point (AP)’, an ‘eNodeB (eNB)’, a ‘5th generation (5G) node’, a ‘wireless point’, and a ‘transmission/reception point (TRP)’ or other term having the equivalent technical meaning.

The UE120is a device used by a user, and communicates with the RAN110over a radio channel. In some cases, the UE120may be operated without user's involvement. For example, the UE120is a device which performs machine type communication (MTC), and is not necessarily carried by the user. The UE120shown inFIG.1may include at least one user portable device, and may include at least one MTC. The UE120ofFIG.1may be referred to as a ‘terminal’, a ‘mobile station’, a ‘subscriber station’, a ‘remote terminal’, a ‘wireless terminal’, a ‘UE’ or a ‘user device’ or other term having the equivalent technical meaning.

An access and mobility management function (AMF)131may be a network entity which manages wireless network access and mobility for the UE120. A session management function (SMF)132may be a network entity which manages connection of a packet data network for providing packet data to the UE120. The connection between the UE120and the SMF132may be a packet data unit (PDU) session.

A user plane function (UPF)133may be a gateway for forwarding packets transmitted and received by the UE120or a network entity serving as the gateway. The UPF133may be connected to a data network (DN)140over an internet, and provide a path for data transmission/reception between the UE120and the DN140. Hence, the UPF133may route data to be delivered over the internet among packets transmitted by the UE120to an internet data network.

A network slice selection function (NSSF)134may be a network entity which performs a network selection operation, for example, an operation of selecting a network slice described in the present disclosure. The operation of the NSSF134will be described in more detail in the drawings to be described.

An authentication server function (AUSF)151may be equipment (a network entity) which provides a service for processing subscriber authentication.

A network exposure function (NEF)152may be a network entity which may access information managing the UE120in the 5G network, subscribe to a mobility management event of the corresponding UE, subscribe to a session management event of a corresponding UE, request session related information, set charging information of the corresponding UE, request to change a PDU session policy for the corresponding UE, and transmit small data of the corresponding UE.

A network repository function (NRF)153may be a network entity (NF) which stores state information of NFs, and has a function of processing requests of other NFs for discovering an accessible NF.

A policy and charging function (PCF)154may be a network entity which applies a service policy, a charging policy, and a PDU session policy of a mobile communication operator for the UE120.

A unified data management (UDM)155may be a network entity which stores information of a subscriber and/or the UE120.

An application function (AF)156may be an NF having a function for providing a service to users by interoperating with a mobile communication network.

A service communication proxy (SCP)157is an NF which provides functions such as NF discovery for communication between NFs, and message transfer between NFs. The SCP157may operate in an integrated form with the NRF153according to an operator's selection, wherein the SCP157may include the functions of the NRF153, or, conversely, the NRF153may be included as a function of the SCP157.

Hereinafter, for convenience of description, subjects which exchange information for the access control and the state management shall be described collectively as NFs. The NF may be, for example, at least one of the AMF131, the SMF132, or the NSSF134. However, the embodiments of the present invention may be equally applied even if the NF is actually implemented as an instance (an AMF instance, an SMF instance, an NSSF instance, etc.).

In various embodiments of the present disclosure, the instance may indicate a state in which a specific NF exists in the form of software code, and a physical computing system, for example, a specific computing system existing on a core network is allocated and executes physical and/or logical resources from a computing system to perform the NF function. Accordingly, the AMF instance, the SMF instance, and the NSSF instance may indicate using the physical and/or logical resources allocated for the AMF, SMF, and NSSF operations respectively from the specific computing system existing on the core network. As a result, the presence of the physical AMF, SMF, and NSSF devices and the AMF instance, the SMF instance, and the NSSF instance using the physical and/or logical resources allocated for the AMF, SMF, and NSSF operations from the specific computing system existing on the core network may perform the same operation. Hence, various embodiments of the present disclosure may be applied by replacing details described with the NF (the AMF, the SMF, the UPF, the NSSF, the NRF, the SCP, etc.) with the NF instance, or, conversely, replacing details described with the NF instance with the individual NF. Likewise, various embodiments of the present disclosure may be applied by replacing details described with a network (NW) slice with a NW slice instance, or conversely, replacing details described with the NW slice instance with the NW slice.

The 3GPP system defines conceptual links for interconnecting NFs in the 5G system as reference points. The following illustrates the reference points included in the 5G system architecture represented inFIG.1.N1: a reference point between the UE and the AMFN2: a reference point between the (R)AN and the AMFN3: a reference point between the (R)AN and the UPFN4: a reference point between the SMF and the UPFN5: a reference point between the PCF and the AFN6: a reference point between the UPF and the DNN7: a reference point between the SMF and the PCFN8: a reference point between the UDM and the AMFN9: a reference point between two core UPFsN10: a reference point between the UDM and the SMFN11: a reference point between the AMF and the SMFN12: a reference point between the AMF and the AUSFN13: a reference point between the UDM and the AUSFN14: a reference point between two AMFsN15: a reference point between the PCF and the AMF in a non-roaming scenario, and a reference point between the PCF and the AMF in a visited network in a roaming scenario

FIG.2illustrates a configuration of a network entity in a wireless communication system according to various embodiments of the present disclosure. The network entity of the present disclosure is a concept including the NF according to system implementation. A term such as ‘unit’ or ‘˜er’ used hereafter indicates a unit for processing at least one function or operation, and may be implemented using hardware, software, or a combination of hardware and software.

The network entity according to various embodiments of the present disclosure may include a communication unit210, a storage unit220, and a control unit230for controlling general operations of the network entity200.

The communication unit210transmits and receives signals with other network entities. Accordingly, whole or part of the communication unit210may be referred to as a transmitter211, a receiver213, or at least one transceiver/transceiver210.

The storage unit220stores data such as a basic program, an application program, and setting information for the operation of the network entity200. The storage unit220may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the storage unit220provides the stored data at a request of the control unit230.

The control unit230controls the general operations of the network entity200. For example, the control unit230transmits and receives signals through the communication unit210. In addition, the control unit230records and reads data in the storage unit220. The control unit230may perform functions of a protocol stack required by a communication standard. For doing so, the control unit230may include a circuit, an application-specific circuit, at least one processor or a micro-processor, or may be a part of a processor. Also, part of the communication unit210and the control unit230may be referred to as a communication processor (CP). The control unit230may control the network entity200to perform any one operation of the various embodiments of the present disclosure.

It is noted that the communication unit210and the control unit230are not implemented necessarily as separate modules, and may be implemented as a single component in the form of a single chip or a software block. The communication unit210, the storage unit220, and the control unit230may be electrically connected. In addition, the operations of the network entity200may be realized by including the storage unit220which stores corresponding program code in the network entity200.

The network entity200includes a network node, and may be any one of a RAN, a UE, an NF, an AMF, an SMF, a UPF, an NEF, an NRF, a CF, an NSSF, a UDM, an AF, an AUSF, an SCP, a UDSF, a context storage, an operations-administration-management (OAM), an element management system (EMS), a configuration server, and an ID management server.

The 5G system according to various embodiments of the present disclosure may include a terminal, a base station, and a 5G core network. The 5G core network may include network functions (NFs) such as AMF, SMF, PCF, UPF, UDM, UDR, NEF, NSSF, NRF, and SCP. According to various embodiments of the present disclosure, the NF may indicate the NE or the network resource. A next generation-radio access network (NG-RAN), a 5G-RAN, or a RAN indicate a base station which provides a wireless communication function to the terminal. The UE may access the 5G core network through the base station.

In addition, various NFs described below may be configured with one specific physical device or two or more physical devices. In addition, the physical devices each may include a program, or software for executing the methods described below under control of a processor included therein. The following description presents only names for the NFs respectively for convenience of explanation, but it is apparent to those skilled in the art that they are implemented as physical devices including at least one processor as above, and are equipped with a program or software for the operations explained in the present disclosure. Accordingly, the expression ‘device’ shall be omitted in the following, and only a specific NF name will be described.

FIG.3illustrates an operation process of a terminal in a wireless communication system according to various embodiments of the present disclosure.

The embodiment ofFIG.3includes a process of selecting a public land mobile network (PLMN) for registering and operating the terminal, and selecting a slice. The embodiment ofFIG.3assumes a condition for the PLMN selection, for example, occurrence of a situation where power on and airplane mode off of the terminal are satisfied, and the PLMN selection is required.

Referring toFIG.3, in step301, the terminal obtains information for the PLMN selection. The information for the PLMN selection may be pre-stored in the terminal, received from a home PLMN (HPLMN), or delivered to the terminal in another separate manner.

In step302, the terminal discovers PLMN candidates accessible at a current location for the PLMN selection. This may be implemented by repeating scanning a frequency band accessible by the terminal, receiving system information broadcast by a base station of an operator in a corresponding band, and detecting a PLMN identifier (ID) included therein.

In step303, the terminal selects at least one PLMN from among the candidate PLMNs. In addition, the terminal selects a PLMN ID of at least one selected PLMN. At this time, the terminal may select the HPLMN first of all, first select a registered PLMN (RPLMN), or select the PLMN of the highest priority among the discovered candidate PLMNs using the aforementioned PLMN selection information (in general, a priority list per PLMN ID).

In step304, the terminal may select a slice to request in a registration process using, if any, information available for the slice selection with respect to the selected PLMN, for example, configured network slice selection assistance information (NSSAI) or allowed NSSAI and otherwise using default configured NSSAI.

In step305, the terminal performs the registration process with the selected PLMN. In addition, if there is the selected slice information, the terminal includes and transmits it in requested NSSAI of a registration request message.

The process described in the embodiment ofFIG.3is based on the process of first selecting the PLMN using the information possessed by the terminal and then selecting the slice to use. However, in some cases, there may exist a basic roaming agreement for a specific subscriber between the HPLMN and a visited PLMN (VPLMN)), but there may be no roaming agreement for the specific slice to be used by the terminal. In this case, since the terminal does not consider the slice information in the PLMN selection, an optimal slice may not be used for the terminal or the registration itself may fail. To address these, the operation process of the terminal according to other embodiments of the present disclosure may include a process where the terminal receives the slice information according to the roaming agreement, and the terminal selects the PLMN having the roaming agreement for the slice to use first by considering the slice information with the roaming agreement in the PLMN selection process.

FIG.4illustrates a process of delivering slice roaming information to a terminal in a wireless communication system according to various embodiments of the present disclosure.

An AMF420and a UDM430ofFIG.4may be NFs of the HPLMN or NFs of the VPLMN. The PLMN may be at least one of the HPLMN or the VPLMN, and each network entity may be applied according to the PLMN.

Referring toFIG.4, in step401, a terminal410performs a registration procedure. The terminal410transmits a registration request message to the AMF420. The PLMN for the registration may be at least one of the HPLMN or the VPLMN.

In step402, the AMF420processes the registration request of the terminal, and transmits a request message for receiving subscription information from the UDM430to the UDM430. At this time, the information requested by the AMF420to the UDM430may include slice roaming information. The request message may be a Nudm_SDM_Get request message, and includes an ID of the terminal (subscriber)410. If UE context of the AMF420includes information that the AMF420should receive the slice roaming information, the AMF420may explicitly notify the UDM430of the slice roaming information request. The slice roaming information may be configured as separate information or may be included in steering of roaming (SoR).

In step403, the UDM430generates and includes a response containing the subscription information of the terminal (subscriber)410, particularly in this embodiment, information for supporting the slice roaming for the subscriber410in a slice roaming container according to the request of the AMF420. The corresponding slice roaming container may include a list of PLMN IDs to be accessed by the terminal410(listed in priority), and a list of slice IDs (S-NSSAI) roaming agreed in each PLMN ID. A specific configuration of the corresponding slice roaming container shall be described in a separate embodiment. In this process, the UDM430may perform a query and response process for receiving information from an NF containing separate subscription information or slice roaming information, for example, a unified data repository (UDR). The slice roaming information may be configured as separate information or may be included in the SoR.

In step403, the PLMN ID to be included by the UDM430in the list may be selected using information received from the AMF420(a country code currently selected by the terminal410or included in a serving PLMN ID or the PLMN ID of the AMF420, or location information of the terminal410) or preset information. For example, using the country code of the serving PLMN ID received from the AMF420, the slice roaming information may be generated based on the PLMN ID accessible in the country where the terminal410is currently located, or the PLMN ID of a neighboring country. Alternatively, the UDM430may generate the slice roaming information based on the roaming service information requested by the subscriber (if the roaming service is requested in advance), the PLMN ID accessible by the subscriber in a country to travel, and the PLMN ID of the neighboring country.

In step404, the UDM430responds to the AMF420with the subscription information of the terminal (subscriber)410, wherein the message used at this time may be a Nudm_SDM_Get response message, and the response message includes the container including the PLMN ID and the slice ID list.

In step405, other steps for the registration may be performed.

In step406, the AMF420transmits a registration response message to the terminal410, and this message includes the container received by the AMF420in step404.

In step407, the terminal410stores the slice roaming or the SoR container received from the AMF420. In addition, the terminal410updates the slice roaming information including the list for the PLMN selection by using the information included in the container. Also, the terminal410may perform an additional operation using the updated slice roaming information. For example, the terminal410may perform the PLMN selection using the updated slice roaming information.

FIG.5illustrates a process of delivering slice roaming information to a terminal in a wireless communication system according to various embodiments of the present disclosure.

Specifically,FIG.5shows the process in which after a registration procedure501of a terminal510is completed, an AMF520forwards slice roaming information to the terminal510using a separate message.

The AMF520and a UDM530ofFIG.5may be NFs of the HPLMN or NFs of the VPLMN. The PLMN may be at least one of the HPLMN or the VPLMN, and each network entity may be applied according to the PLMN.

Referring toFIG.5, in step501, the terminal510is registered at a specific PLMN.

In step502, the UDM530includes and generates information for supporting the slice roaming in the slice roaming container. The corresponding slice roaming container may include a list of PLMN IDs to be accessed by the terminal510and a list of slice IDs (S-NSSAI) roaming-agreed in each PLMN ID. The list of the PLMN IDs to be accessed by the terminal510may be contained in the slice roaming container based on the priority. A specific configuration of the corresponding slice roaming container will be described in a separate embodiment. During the process of step502, the UDM530may perform a query response process for receiving information from the NF containing the separate subscription information or the slice roaming information, for example, the UDR. The slice roaming information may be configured as separate information or may be included in the SoR.

In step502, the PLMN ID to be included by the UDM530in the list may be selected using information pre-received from the AMF520which serves the terminal510(a country code included in the serving PLMN ID or the PLMN ID of the AMF520, or location information stored of the terminal510), or preset information. For example, using the country code of the serving PLMN ID received from the AMF520, the slice roaming information may be generated based on the PLMN ID accessible in the country where the terminal410is currently located, or a PLMN ID of a neighboring country. Alternatively, the UDM430may generate the slice roaming information based on the roaming service information requested by the subscriber510(if the roaming service is requested in advance), the PLMN ID accessible by the subscriber510in a country to travel, and the PLMN ID of the neighboring country.

In step503. the UDM530performs notification for forwarding the slice roaming information of the terminal (subscriber)510to the AMF520. At this time, the notification message used may be an Ndum_SDM_Notification message. According to an embodiment, the Ndum_SDM_Notification message may include the slice roaming container including the PLMN ID and the slice ID list.

In step504, the AMF520receiving the notification message from the UDM530transmits a downlink (DL) non-access-stratum (NAS) transport message including the received slice roaming container to the terminal510.

In step505, the terminal510may transmit an acknowledgment (ACK) for the received DL NAS transmission message. Specifically, the terminal510may transmit an uplink (UL) NAS transport message to the AMF520.

In step506, the AMF520may transmit a notification result to the UDM530. Specifically, the AMF520may transmit a Nudm_SDM_info message to the UDM530.

In step507, the terminal510stores the slice roaming or the SoR container received from the AMF520. In addition, the terminal510updates the slice roaming information including the list for the PLMN selection by using the information included in the container. Also, the terminal510may perform an additional operation using the updated slice roaming information. For example, the terminal510may perform the PLMN selection using the updated slice roaming information.

In various embodiments of the present disclosure, a method of configuring and transferring slice roaming information to a terminal is as follows.a first method: using a transparent container for slice roaming; ora second method: including slice roaming information in a SoR container

In the first method, information indicating that a container type is the transparent container including the information for the slice roaming may be included in the delivery from the UDM to the AMF and from the AMF to the terminal.

The following [Table 1] shows an example of a configuration of the transparent container. Referring to [Table 1], the container may be expressed as a list of one or more slice IDs (S-NSSAI or slice ID of other type) for supporting the roaming per PLMN ID. The priority increases as approaching 1.

TABLE 1PLMN ID 1Slice identifier 1. . .PLMN ID nSlice identifier n

The following [Table 2] shows another example of the configuration of the transparent container. Referring to [Table 2], the container may be expressed as a list indicating only whether the slice roaming is supported per PLMN ID. The priority increases from 1 to n.

TABLE 2PLMN ID 1Slice roaming supported indicator. . .PLMN ID nSlice roaming supported indicator

In [Table 1] or [Table 2], the information delivered through the transparent container may be delivered using the SoR container rather than a separate container for the slice roaming. If the SoR container needs to include an access technology ID list for each PLMN ID, pieces of two information (i.e., the access technology ID list per PLMN ID and the slice ID list with the roaming agreed per PLMN ID) may be included in separate SoR containers, or may be included in one SoR container.

The following [Table 3] shows an example of the configuration of the SoR container. Referring to [Table 3], the access technology ID per PLMN ID and the slice ID or the slice roaming indicator are delivered together through the SoR container.

TABLE 3PLMN ID 1access technology identifier 1Slice roaming support indicator or supported slice ID 1. . .PLMN ID naccess technology identifier nSlice roaming support indicator or supported slice ID n

Yet another method is to use two SoR containers, by separating the SoR container which contains the access technology ID per PLMN ID and the SoR container which contains the slice information.

Meanwhile, a header of an information element (IE) containing the SoR or the slice roaming information may include information indicating the type of the current container (i.e., whether the current container is the SoR, the slice roaming, the ACK, etc.), and information indicating the type of the list included in the actual container, that is, a secured packet, the PLMN ID and the access technology ID, the PLMN ID and the slice roaming support indicator, the PLMN ID and the slice identifier supporting the roaming, or whether the PLMN ID, the access technology ID, and the slice roaming information are included.

The above-mentioned [Table 1] through [Table 3] are merely examples of the configuration of the transparent container or the SoR container. The configuration of the transparent container or the SoR container according to various embodiments of the present disclosure is not limited to the configurations of [Table 1] through [Table 3], and it is apparent that an additional configuration in addition to the configurations of [Table 1] through [Table 3] described above may be included in the transparent container or the SoR container.

Hereinafter, inFIG.6throughFIG.8, various embodiments of the present disclosure suggest a method for changing a PLMN selection operation of a terminal.

FIG.6illustrates a process of delivering a priority for a PLMN selection operation to a terminal in a wireless communication system according to various embodiments of the present disclosure.

An AMF620and a UDM630ofFIG.6may be NFs of the HPLMN or NFs of the VPLMN. The PLMN may be at least one of the HPLMN or the VPLMN, and each network entity may be applied according to the PLMN.

Referring toFIG.6, in step601, a terminal610transmits a registration request message to the AMF620.

In step602, the AMF620requests subscription information from the UDM630in registration processing. Specifically, it transmits a Nudm_SDM_Get request message to the AMF620. The Nudm_SDM_Get request message may include an ID of the terminal610.

In step603, the UDM630determines to forward information for setting or changing a PLMN selection mode of the terminal610, by considering subscription information of the terminal (subscriber)610, the PLMN currently accessed by the terminal610, and operator settings. The PLMN selection mode is information which notifies a preferred scheme among the existing PLMN selection operating regardless of the slice roaming, or the PLMN selection scheme considering whether the slice roaming is performed. If the information of the PLMN selection mode is absent, the existing PLMN selection is applied. According to an embodiment, the UDM630checks a preference of an operator (a PLMN operator) for the slice selection mode and subscription data of the terminal.

In step604, the UDM630forwards the information of the PLMN selection mode to the AMF620. Specifically, the UDM630transmits a Nudm_SDM_Get response message to the AMF620. The Nudm_SDM_Get response message may include the PLMN or the slice selection mode.

In step605, the UDM630may perform operations of other steps for the registration.

In step606, the AMF620forwards the PLMN selection mode to the terminal610through a response message to the registration. Specifically, the AMF620transmits a registration response message to the terminal610. The registration response message may include the PLMN or the slice selection mode.

In step607, the terminal610stores the PLMN selection mode set by the HPLMN received from the AMF620. In addition, the terminal610updates the PLMN or the slice selection mode. Also, the terminal610may perform an additional operation using the updated PLMN or slice selection mode. For example, the terminal610may perform a PLMN selection operation using the updated PLMN or slice selection mode.

FIG.7illustrates a process of delivering a priority for a PLMN selection operation to a terminal in a wireless communication system according to various embodiments of the present disclosure.

An AMF720and a UDM730ofFIG.7may be NFs of the HPLMN or NFs of the VPLMN. The PLMN may be at least one of the HPLMN or the VPLMN, and each network entity may be applied according to the PLMN.

Referring toFIG.7, in step701, a terminal710is registered at a specific PLMN.

In step702, the UDM730determines to forward information for setting or changing a PLMN selection mode of the terminal710, by considering subscription information of the terminal (subscriber)710, the PLMN currently accessed by the terminal710, and operator settings. The PLMN selection mode is information indicating a preferred scheme among the existing PLMN selection which operates regardless of the slice roaming, or the PLMN selection scheme considering whether the slice roaming is performed. If the information of the PLMN selection mode is absent, the existing PLMN selection is applied. According to an embodiment, the UDM730checks a preference of an operator (a PLMN operator) for the slice selection mode and subscription data of the terminal.

In step703, the UDM730forwards information of the PLMN selection mode to the AMF720. Specifically, the UDM730transmits a Nudm_SDM_Notification message to the AMF720. The Nudm_SDM_Notification message may include the PLMN or the slice selection mode.

In step704, the AMF720forwards the PLMN selection mode to the terminal704using a DL NAS transport message. The DL NAS transport message may include the PLMN or the slice selection mode.

In step705, the terminal710may forward an ACK to the received mode information using a UL NAS transport message.

In step706, the AMF720may notify the UDM730of the HPLMN that the received information has been forwarded to the terminal710. Specifically, the AMF720transmits a Nudm_SDM_Info message to the UDM730.

In step707, the terminal710stores the PLMN selection mode set by the HPLMN received from the AMF720. In addition, the terminal710updates the PLMN or the slice selection mode. Also, the terminal710may perform an additional operation using the updated PLMN or slice selection mode. For example, the terminal710may perform a PLMN selection operation using the updated PLMN or slice selection mode.

FIG.8illustrates a process of a terminal for selecting a PLMN or a process for selecting a PLMN in consideration of slice roaming in a wireless communication system according to various embodiments of the present disclosure.

Referring toFIG.8, in step801, the terminal obtains information for performing PLMN selection. The terminal may receive the information for performing the PLMN selection from the network. Alternatively, the information for performing the PLMN selection may be preset in the terminal. Alternatively, the information for performing the PLMN selection may be information received and stored in advance from the network through various embodiments of the present invention. According to various embodiments of the present disclosure, the information for performing the PLMN selection may be a container or a SoR container which contains a priority list of PLMN IDs or a PLMN ID list including roaming support slice information.

In step802, the terminal determines whether it is necessary to perform the PLMN selection in consideration of the slice roaming based on the information for performing the PLMN selection obtained in step801. If it is determined that it is necessary to perform the PLMN selection in consideration of the slice roaming, the terminal proceeds to step803. If it is determined that it is not necessary to perform the PLMN selection in consideration of the slice roaming, the terminal proceeds to step806.

According to various embodiments of the present disclosure, whether it is necessary to perform the PLMN selection in consideration of the slice roaming may be determined based on whether the terminal has the information for PLMN selection considering the slice roaming. Alternatively, according to various embodiments of the present disclosure, whether it is necessary to perform the PLMN selection in consideration of the slice roaming may be determined based on whether the terminal explicitly receives from the network a message that the PLMN selection mode precedes the PLMN selection considering the slice roaming in addition to the information for the PLMN selection in consideration of the slice roaming.

In step803, the terminal scans for a PLMN accessible at a current location, and discovers candidate PLMNs.

In step804, the terminal selects a PLMN/PLMN ID of the highest priority among PLMNs for supporting the slice roaming. Specifically, the terminal discovers the PLMN optimally matched to the slice roaming. The operation of step804may be performed using a priority list of PLMN/PLMN IDs in consideration of the slice roaming obtained by the terminal in advance. At this time, if the terminal may use two or more network slices, it may select one of the highest priority among PLMN IDs of PLMNs for simultaneously supporting the most slices with the high priority. In step804, the terminal may use a local configuration as priority policy (a network slice selection policy (NSSP) included in a UE route selection policy (URSP)) or configuration information of the slice to be used by the terminal.

In step805, if the terminal succeeds in selecting the available PLMN through the process of step804, it proceeds to step807and finishes the process of the PLMN selection. If the terminal does not succeed in selecting the available PLMN through the process of step804, it proceeds to step806.

In step806, the terminal performs the PLMN selection operation by applying normal PLMN selection not considering the slice roaming.

The methods according to the embodiments described in the claims or the specification of the present disclosure may be implemented in software, hardware, or a combination of hardware and software.

As for the software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured for execution by one or more processors of an electronic device. One or more programs may include instructions for controlling an electronic device to execute the methods according to the embodiments described in the claims or the specification of the present disclosure.

Such a program (software module, software) may be stored to a random access memory, a non-volatile memory including a flash memory, a read only memory (ROM), an electrically erasable programmable ROM (EEPROM), a magnetic disc storage device, a compact disc (CD)-ROM, digital versatile discs (DVDs) or other optical storage devices, and a magnetic cassette. Alternatively, it may be stored to a memory combining part or all of those recording media. A plurality of memories may be included.

Also, the program may be stored in an attachable storage device accessible via a communication network such as internet, intranet, local area network (LAN), wide LAN (WLAN), or storage area network (SAN), or a communication network by combining these networks. Such a storage device may access a device which executes an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may access the device which executes an embodiment of the present disclosure.

In the specific embodiments of the present disclosure, the components included in the present disclosure are expressed in a singular or plural form. However, the singular or plural expression is appropriately selected according to a proposed situation for the convenience of explanation, the present disclosure is not limited to a single component or a plurality of components, the components expressed in the plural form may be configured as a single component, and the components expressed in the singular form may be configured as a plurality of components.

Meanwhile, while the specific embodiment has been described in the detailed explanations of the present disclosure, it will be noted that various changes may be made therein without departing from the scope of the present disclosure.

The present disclosure generally relates to a wireless communication system, and more particularly, to an apparatus and a method for supporting slice federation between public land mobile network (PLMN) operators in the wireless communication system.