Patent Publication Number: US-2023147538-A1

Title: Session management method according to application of user equipment policy in wireless communication system

Description:
TECHNICAL HELD 
     The present disclosure relates to a method and apparatus for providing a service in a wireless communication system, and more particularly, to a method and apparatus for providing a service requested by a user equipment, in a wireless communication system. 
     BACKGROUND ART 
     To meet the ever-increasing demand with respect to wireless data traffic since the commercialization of the 4th generation (4G) communication system, there have been efforts to develop an advanced 5th generation (5G) or pre-5G communication system. This is one reason why ‘5G communication systems’ or ‘pre-5G communication systems’ are called ‘beyond 4G network communication systems’ or ‘post Long-Term Evolution (LTE) systems.’ In order to achieve a high data rate, consideration is given to implementing 5G communication systems in millimeter wave (mmW) frequency bands (e.g., 60 gigahertz (GHz) bands), In order to reduce path loss of radio waves and increase a propagation distance of radio waves in superhigh frequency bands, in 5G communication systems, discussions are underway about technologies such as beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large scale antennas. Also, in order to improve networks of systems, in 5G communication systems, development of technologies such as evolved small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (COMP), and received-interference cancellation is underway. In addition, for 5G systems, advanced coding modulation (ACM) technologies such as hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) (FOAM) and sliding window superposition coding (MSC), and advanced access technologies such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), have been developed. 
     The Internet has evolved from a human-based connection network, where humans create and consume information, to the Internet of things (IoT), where distributed elements such as objects exchange information with each other to process the information. Internet of Everything (IoE) technology, which is a combination of IoT technology and big data processing technology through connection with a cloud server, is also emerging. In order to implement the IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and thus technology for inter-object connection, such as sensor network, machine to machine (M2M) communication, or machine-type communication (MTC), has recently been studied. In an IoT environment, intelligent Internet technology (IT) services that collect and analyze data generated by connected objects and create new value in human life may be provided. IoT may be applied to a variety of areas, such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grid, health care, smart home appliances and advanced medical services through convergence and combination between existing information technologies (IT) and various industrial applications. 
     Various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies related to sensor networks, M2M communication, and MTC are being implemented by using 5G communication technology including beamforming, MIMO, and array antennas. The application of a cloud RAN as big data processing technology may also be considered as an example of convergence of 5G technology and IoT technology. 
     As described above, various services may be provided due to the development of wireless communication systems, and thus, there is a need for methods of seamlessly providing such services. 
     DESCRIPTION OF EMBODIMENTS 
     Technical Problem 
     Provided are an apparatus and method for effectively providing a service in a wireless communication system. 
     Solution to Problem 
     According to an embodiment of the present disclosure, a policy control function (PCF) entity for managing policies may be provided. The PCF entity may be configured to transmit User Equipment Route Selection Policy (URSP) information including first Data Network Name (DNN) information to a user equipment through an Access and Mobility management Function (AMF), identify a triggering event to update the URSP, transmit, based on the identified triggering event, updated URSP information including second DNN information to the user equipment through the AMF, transmit a Session Management Function (SMF) selection management trigger message to the AMF, when transmitting the updated URSP information including the second DNN information, and receive a user equipment policy update request message from the AMF when a request from the AMF for at least one of a first DNN corresponding to the first DNN information or a third DNN is detected. 
     Advantageous Effects of Disclosure 
     The disclosed embodiments provide apparatuses and methods capable of effectively providing services in a wireless communication system. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a view illustrating a network structure of a 5G system (5GS) according to an embodiment of the present disclosure. 
         FIG.  2    is a sequence diagram illustrating a user equipment registration procedure according to an embodiment of the present disclosure. 
         FIG.  3    is a sequence diagram illustrating a UE policy update procedure according to an embodiment of the present disclosure. 
         FIG.  4    is a sequence diagram illustrating a UE policy update procedure according to an embodiment of the present disclosure. 
         FIG.  5    is a sequence diagram illustrating a policy update procedure according to an embodiment of the present disclosure. 
         FIG.  6    is a sequence diagram illustrating a policy update procedure according to an embodiment of the present disclosure. 
         FIG.  7    is a sequence diagram illustrating a PDU session establishment procedure according to an embodiment of the present disclosure. 
         FIG.  8    is a block diagram illustrating a structure of a user equipment according to an embodiment of the present disclosure. 
         FIG.  9    is a block diagram illustrating a structure of a core network entity according to an embodiment of the present disclosure. 
         FIG.  10    is a flowchart of an operating method of a user equipment, according to an embodiment of the present disclosure. 
         FIG.  11    is a flowchart of an operating method of a policy control function (PCF), according to an embodiment of the present disclosure. 
     
    
    
     BEST MODE 
     A policy control function (PCF) entity for managing policies, according to an embodiment of the present disclosure, may include a transceiver and at least one processor. The at least one processor may be configured to transmit User Equipment Route Selection Policy (URSP) information including first Data Network Name (DNN) information to a user equipment through an Access and Mobility management Function (AMF), identify a triggering event to update the URSP, transmit, based on the identified triggering event, updated URSP information including second DNN information to the user equipment through the AMF, transmit a Session Management Function (SMF) selection management trigger message to the AMF, when transmitting the updated URSP information including the second DNN information, and receive a user equipment policy update request message from the AMF when a request from the AMF for at least one of a first DNN corresponding to the first DNN information or a third DNN is detected. 
     In an embodiment, the at least one processor may be further configured to select a DNN based on the received user equipment policy update request message, and provide the selected DNN to the AMF, wherein the selected DNN includes the second DNN. 
     In an embodiment, a Protocol Data Unit (PDU) session between the user equipment and a network may be established based on the selected DNN information, after a Session Management Function (SMF) has received, from the AMF, a PDU session management context request message including information about the selected DNN and user equipment-requested DNN information. 
     In an embodiment, the SMF selection management trigger message may include the first Data Network Name (DNN) information. 
     In an embodiment, the updated URSP information and the SMF selection management trigger message may be included in a single message and transmitted or are included in different messages and transmitted. 
     In an embodiment, the triggering event to update the URSP may be identified based on at least one of user equipment subscription information, operator policy information, information received from the user equipment, or information received from the AMF. 
     In an embodiment, a PDU session between the user equipment and a network 
     may be established based on a result of comparing at least one of the first DNN information received by the AMF from the PCF or information received by the AMF from a Unified Data Management (UDM) with user equipment-requested DNN information received from the user equipment. 
     A user equipment in a wireless communication system, according to another embodiment of the present disclosure, includes: a transceiver; and at least one processor, wherein the at least one processor is configured to: receive, from an Access and Mobility management Function (AMF), User Equipment Route Selection Policy (URSP) information including first data Network Name (DNN) information provided by a policy control function (PCF), transmit, to the AMF based on the received URSP information, a protocol data unit (PDU) session establishment request message including user equipment-requested DNN information about at least one of a first DNN corresponding to the first DNN information or a third DNN, wherein a PDU session between the user equipment and a network is established based on the selected DNN information, after a Session Management Function (SMF) has received, from the AMF, a PDU session management context request message including information about a DNN selected by the PCF and the user equipment-requested DNN information, and the information about the DNN selected by the PCF includes second DNN information that is different from the first DNN and the third DNN. 
     In an embodiment, the PDU session may be established based on a result of comparing at least one of the first DNN information received by the AMF from the PCF or information received from a Unified Data Management (UDM) with the user equipment-requested DNN information. 
     An Access and Mobility management function (AMF) entity for managing policies, according to another embodiment of the present disclosure, includes: a transceiver; and at least one processor, wherein the at least one processor is configured to receive a Session Management Function (SMF) selection management trigger message, when receiving updated URSP information including second DNN information from a policy control function (PCF), transmit the received updated URSP information to a user equipment, receive, from the user equipment, a protocol data unit (PDU) session establishment request message including user equipment-requested DNN information corresponding to a first DNN, detect, based on the received PDU session establishment request message, the user equipment requesting the first DNN, and transmit a user equipment policy update request message to the PCF. 
     In an embodiment, the at least one processor may be further configured to transmit, to the Session Management Function (SMF), a session management context request message including DNN information selected by the PCF or the user equipment-requested DNN information. 
     In an embodiment, the at least one processor may be further configured to receive, from the PCF, DNN information selected based on the user equipment policy update request message, wherein the selected DNN includes the second DNN. 
     In an embodiment, the at least one processor may be further configured to receive, from the PCF, in response to the user equipment policy update request message, a user equipment policy update response message including DNN information selected by the PCF, transmit, to an Session Management Function (SMF), a protocol data unit (PDU) session management context request message including information about the selected DNN and user equipment-requested DNN information, wherein a PDU session between the user equipment and a network is established based on the selected DNN information after the Session Management Function (SMF) has received the PDU session management context request message from the AMF. 
     In an embodiment, the SMF selection management trigger message may include the first DNN information. 
     In an embodiment, the updated URSP information and the SMF selection management trigger message may be included in a single message and transmitted or are included in different messages and transmitted. 
     In an embodiment, the at least one processor may be configured to identify that the second DNN information does not match the user equipment-requested DNN information, and transmit a user equipment policy update request message to the PCF based on a result of the identifying. 
     An operating method of a policy control function (PCF) entity for managing policies, according to another embodiment of the present disclosure, includes transmitting, to a user equipment, User Equipment Route Selection Policy (URSP) information including first Data Network Name (DNN) information to a user equipment through an Access and Mobility management Function (AMF), identifying a triggering event to update the URSP, transmitting, based on the identified triggering event, updated URSP information including second DNN information to the user equipment through the AMF, transmitting a Session Management Function (SMF) selection management trigger message to the AMF, when transmitting the updated URSP information including the second DNN information, and receiving a user equipment policy update request message from the AMF when a request from the AMF for at least one of a first DNN corresponding to the first DNN information or a third DNN is detected. 
     An operating method of a user equipment in a wireless communication system, according to another embodiment of the present disclosure, includes receiving, from an Access and Mobility management Function (AMF), User Equipment Route Selection Policy (URSP) information including first data Network Name (DNN) information provided by a policy control function (PCF), and transmitting, to the AMF based on the received URSP information, a protocol data unit (PDU) session establishment request message including user equipment-requested DNN information about at least one of a first DNN corresponding to the first DNN information or a third DNN, wherein a PDU session between the user equipment and a network is established based on the selected DNN information, after a Session Management Function (SMF) has received, from the AMF, a PDU session management context request message including information about a DNN selected by the PCF and the user equipment-requested DNN information, and the information about the DNN selected by the PCF includes second DNN information that is different from the first DNN and the third DNN. 
     An operating method of an Access and Mobility management Function (AMF) entity for managing policies, according to another embodiment of the present disclosure, includes receiving a Session Management Function (SMF) selection management trigger message, when receiving updated URSP information including second DNN information from a policy control function (PCF), transmitting the received updated URSP information to a user equipment, receiving, from the user equipment, a protocol data unit (PDU) session establishment request message including user equipment-requested DNN information corresponding to a first DNN, detecting, based on the received PDU session establishment request message, the user equipment requesting the first DNN, and transmitting a user equipment policy update request message to the PCF. 
     Mode of Disclosure 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. While describing the present disclosure, detailed descriptions of related well-known functions or configurations that may blur the points of the present disclosure are omitted. The terms used herein are those defined in consideration of functions in regard to the present disclosure, but the terms may vary according to the intention of users or operators, precedents, etc, Thus, the terms used in the specification should be understood based on the overall description of the present disclosure. 
     The advantages and features of the present disclosure and methods of achieving them will become apparent with reference to embodiments of the present disclosure described in detail below along with the attached drawings. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to embodiments of the present disclosure set forth herein; rather these embodiments of the present disclosure are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to one of ordinary skill in the art, and the scope of the present disclosure is defined only by the accompanying claims. In the specification, the same reference numerals denote the same elements. 
     It will be understood that blocks in flowcharts or combinations of the flowcharts may be performed by computer program instructions, Because these computer program instructions may be loaded into a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus, the instructions, which are executed via the processor of the computer or other programmable data processing apparatus generate means for implementing the functions specified in the flowchart block(s), These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable memory produce a manufactured article including instruction means that perform the functions specified in the flowchart block(s). The computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable data processing equipment to produce a computer-executable process such that the instructions that are executed on the computer or other programmable data processing equipment provide steps for implementing the functions specified in the flowchart block(s). 
     Also, each block of the flowchart illustrations may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order shown. For example, two consecutive blocks may also be executed simultaneously or in reverse order depending on functions corresponding thereto. 
     As used herein, the term “ . . . unit” denotes a software element or a hardware element such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), and performs a certain function. However, “ . . . unit” does not mean to be limited to software or hardware. The term “ . . . unit” may be configured to be in an addressable storage medium or configured to operate one or more processors. Thus, the term ‘ . . . unit’ or ‘ . . . er(or)’ may include, by way of example, object-oriented software components, class components, and task components, and processes, functions, attributes, procedures, subroutines, segments of a program code, drivers, firmware, a micro code, a circuit, data, a database, data structures, tables, arrays, and variables. The functionality provided in components and “ . . . units” may be combined into fewer components and “ . . . units” or further separated into additional components and “ . . . units”. Further, components and “ . . . units” may be implemented to operate one or more central processing units (CPUs) in a device or a secure multimedia card. Also, the “ . . . unit” may include at least one processor. 
     In the description of the present disclosure, certain detailed explanations of related art are omitted when it is deemed that they may unnecessarily obscure the essence of the present disclosure. Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. 
     Hereinafter, terms indicating a connection node, terms indicating network entities, terms indicating messages, terms indicating an interface between network entities, and terms indicating various pieces of identification information used herein are exemplified for convenience of description. Thus, the present disclosure is not limited by the following terms, and other terms having equivalent technical meaning may be used. 
     Hereinafter, some terms and names defined in the 3rd generation partnership project long term evolution (3GPP LTE) standard or 5G standards may be used for convenience of description. The present disclosure is not, however, limited by the terms and definitions, and may be equally applied to any systems that conform to other standards. In particular, the present disclosure may be applied to a 3GPP New Radio (NR, 5th Generation mobile communication standards). In the present disclosure, an evolved node B (eNB) may be interchangeably used with a next generation node B (gNB) for convenience of description. That is, a base station described as an eNB may refer to a gNB. Alternatively, a base station described as a gNB may refer to an eNB. Alternatively, a node described as a base station may refer to eNB or gNB. Also, the term “user equipment” may refer to other wireless communication devices as well as mobile phones, NB-IoT devices, and sensors. 
     Hereinafter, a base station is an entity that assigns resources of a user equipment, and may be at least one of a gNode B, an eNode B, a base station (BS), a wireless access unit, a base station controller, or a node on a network. Examples of a user equipment may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. However, the present disclosure is not limited to the above examples. 
     In the present disclosure, the term “service” may be interchangeably used to refer to a specific communication equipment (or a Network Function (NF)) performing a request of another communication equipment (or an NF) (that is, referring to an NF service), services provided by a mobile communication operator (i.e., voice service, text service, data service, etc.), and services provided by Over The Top (OTT) operators (i.e., messenger service, game service, etc.). 
     The wireless communication system may provide access/registration (attach, registration) and session connection (PDN connection, PDU session) of a user equipment to provide a service. To this end, a protocol between a user equipment (UE) and a Network Function (NF) of a mobile communication system may be defined, and the user equipment and the NF may exchange various parameters defined by a control plane signaling protocol. 
     According to embodiments of the present disclosure, when the parameters (e.g., Data Network Name (DNN), Single Network Slice Selection Assistance Information (S-NSSAI), etc.) transmitted by the user equipment to the NF are not valid, or when the parameters are not available for provision in a wireless communication system (e.g., 5GS, EPS, etc.), instead of rejecting a request from the user equipment (session release), the parameters transmitted by the user equipment may be replaced by available parameters to thereby prevent service errors or a decrease in customer service quality. Alternatively, according to the embodiments of the present disclosure, service errors or a decrease in customer service quality may be prevented by temporarily granting a request from the user equipment, instead of rejecting the request (session release). Alternatively, according to the embodiments of the present disclosure, the user equipment may be induced to use the correct parameters by notifying, by a network, the user equipment of the cause of rejecting the request from the user equipment (session release). 
       FIG.  1    is a view illustrating a network structure of a 5G system (5GS) according to an embodiment of the present disclosure. 
     Referring to  FIG.  1   , a 5G core network may be composed of an Access and Mobility Management Function (AMF)  120 , a Session Management Function (SMF)  135 , a User Plane Function (UPF)  130 , Policy Control Functions (PCF)  140 ,  141 , a Unified Data Management (UDM)  145 , a Network Slice Selection Function (NSSF)  160 , an Authentication Server Function (AUSF)  165 , a Unified Data Repository (UDR)  150 , and the like. The user equipment  100  may access the 5G core network through a base station  110 . Hereinafter, the UE  100  may be referred to as a user equipment  100 , and a (R)AN  110  may be referred to as the base station  110 . In addition, the 5G core network may further include an Application Function (AF)  170  and a Data Network (DN)  175 . 
     According to an embodiment, the AMF  120  is a network function (NF) that manages wireless network access and mobility for the user equipment  100 . 
     The SMF  135  is an NF that manages a session for the user equipment  100 , and session information thereof includes Quality of Service (QoS) information, charging information, and packet processing information. 
     The UPF  130  is an NF that processes user traffic (e.g., user plane traffic), and is controlled by the SMF  135 . 
     The PCFs  140  and  141  are NFs that manage operator policy (PLMN policy) for providing a service in a wireless communication system. In addition, the PCFs may be divided into a PCF  140  which is in charge of Access and Mobility (AM) policy and UE policy, and a PCF  141  which is in charge of Session Management (SM) policy. The PCF  140  and the PCF  141  may be logically or physically separated NFs or may be logically or physically one single NF. [Table 1] shows examples of AM policies managed by the PCF  140 . [Table 2-1], [Table 2-2], and [Table 2-3] show examples of UE policies managed by the PCF  140 . [Table 3] shows examples of SM policies managed by the PCF  141 . 
     As a method of managing the UE policy, the PCF  140  may divide the UE policy into one or more policy sections. One policy section may be divided or indicated by a Policy Section Identifier (PSI). For example, the PCF  140  may allocate the entire UE policy for the user equipment (i.e., all UE route selection policy (URSP) rules) to one policy section. Alternatively, the PCF  140  may allocate one or several URSP rules among the UE policy for the user equipment  100 , to one policy section. The PCF  140  may store and manage latest UE policy-related information (e.g., a list of PSIs) of the user equipment  100 . 
     The user equipment  100  may transmit, to the AMF  120 , information related to UE policy stored in the user equipment  100  (e.g., a list of PSIs), during a registration procedure. The AMF  120  may transmit the received UE policy-related information (e.g., a list of PSIs) to the PCF  140 . The PCF  140  may compare the received UE policy-related information with the latest UE policy-related information stored in the PCF  140  or obtained from the UDR  150  (e.g., the latest list of PSIs). When the UE policy-related information received from the user equipment does not match the latest UE policy-related information, the PCF  140  may determine that the user equipment  100  is not storing the latest UE policy information, and transmit the latest UE policy information to the user equipment  100 . 
     Alternatively, the PCF  140  may determine a new UE policy based on a change in user equipment subscription information, operator policy, and the like. The PCF  140  may allocate a PSI indicating a new UE policy. The PCF  140  may transmit, to the user equipment  100 , the new UE policy and latest PSI first information corresponding thereto. When user equipment transmission is successful, the PCF  140  may store the new UE policy and the latest PSI list information corresponding thereto, in the UDR  150 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Access and mobility related policy control information 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 PCF permitted 
                   
               
               
                   
                   
                   
                 to modify in a 
               
               
                 Information 
                   
                   
                 UE context in 
               
               
                 name 
                 Description 
                 Category 
                 the AMF 
                 Scope 
               
               
                   
               
               
                 Service Area 
                 This part defines the service 
                   
                   
                   
               
               
                 Restrictions 
                 area restrictions. 
               
               
                 List of allowed 
                 List of allowed TAIs 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 TAIs. 
                 (NOTE 3) (NOTE 4). 
                 (NOTE 1) 
               
               
                 List of non- 
                 List of non-allowed TAIs 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 allowed TAIs. 
                 (NOTE 3). 
                 (NOTE 1) 
               
               
                 Maximum number 
                 The maximum number of 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 of allowed TAIs 
                 allowed TAIs. 
                 (NOTE 1) 
               
               
                   
                 (NOTE 4) 
               
               
                 RFSP Index 
                 This part defines the RFSP 
               
               
                   
                 index 
               
               
                 RFSP Index 
                 Defines the RFSP Index that 
                 Conditional 
                 Yes 
                 UE context 
               
               
                   
                 applies for a UE 
                 (NOTE 2) 
               
               
                 UE-AMBR 
                 This defines the UE-AMBR 
                 Conditional 
                 Yes 
                 UE context 
               
               
                   
                 value that applies for a UE 
                 (NOTE 5) 
               
               
                 SMF selection 
                 This part defines the SMF 
               
               
                 management 
                 selection management 
               
               
                   
                 instructions 
               
               
                 DNN replacement 
                 Defines if a UE requested 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 of unsupported 
                 unsupported DNN is requested 
                 (NOTE 6) 
               
               
                 DNNs 
                 for replacement by PCF 
               
               
                 List of 
                 Defines the list of S-NSSAIs 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 S-NSSAIs 
                 containing DNN candidates for 
                 (NOTE 6) 
               
               
                   
                 replacement by PCF 
                 (NOTE 7) 
               
               
                 Per S-NSSAI: 
                 Defines UE requested DNN 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 List of DNNs 
                 candidates for replacement by 
                 (NOTE 6) 
               
               
                   
                 PCF 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2-1 
               
             
            
               
                   
               
               
                 UE Route Selection Policy (URSP) 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 PCF permitted 
                   
               
               
                 Information 
                   
                   
                 to modify in a 
               
               
                 name 
                 Description 
                 Category 
                 URSP 
                 Scope 
               
               
                   
               
               
                 URSP rules 
                 1 or more URSP rules as 
                 Mandatory 
                 Yes 
                 UE context 
               
               
                   
                 specified in table 6.6.2.1-2 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2-2 
               
             
            
               
                   
               
               
                 UE Route Selection Policy Rule 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 PCF permitted 
                   
               
               
                 Information 
                   
                   
                 to modify in a 
               
               
                 name 
                 Description 
                 Category 
                 UE context 
                 Scope 
               
               
                   
               
               
                 Rule 
                 Determines the order the 
                 Mandatory 
                 Yes 
                 UE context 
               
               
                 Precedence 
                 URSP rule is enforced in the 
                 (NOTE 1) 
               
               
                   
                 UE. 
               
               
                 Traffic 
                 This part defines the Traffic 
                 Mandatory 
               
               
                 descriptor 
                 descriptor components for the 
                 (NOTE 3) 
               
               
                   
                 URSP rule. 
               
               
                 Application 
                 It consists of OSId and 
                 Optional 
                 Yes 
                 UE context 
               
               
                 descriptors 
                 OSAppId(s). (NOTE 2) 
               
               
                 IP 
                 Destination IP 3 tuple(s) (IP 
                 Optional 
                 Yes 
                 UE context 
               
               
                 descriptors 
                 address or IPv6 network prefix, 
               
               
                 (NOTE 5) 
                 port number, protocol ID of the 
               
               
                   
                 protocol above IP). 
               
               
                 Domain 
                 Destination FQDN(s) 
                 Optional 
                 Yes 
                 UE context 
               
               
                 descriptors 
               
               
                 Non-IP 
                 Descriptor(s) for destination 
                 Optional 
                 Yes 
                 UE context 
               
               
                 descriptors 
                 information of non-IP traffic 
               
               
                 (NOTE 5) 
               
               
                 DNN 
                 This is matched against the 
                 Optional 
                 Yes 
                 UE context 
               
               
                   
                 DNN information provided by 
               
               
                   
                 the application. 
               
               
                 Connection 
                 This is matched against the 
                 Optional 
                 Yes 
                 UE context 
               
               
                 Capabilities 
                 information provided by a UE 
               
               
                   
                 application when it requests a 
               
               
                   
                 network connection with certain 
               
               
                   
                 capabilities. (NOTE 4) 
               
               
                 List of Route 
                 A list of Route Selection 
                 Mandatory 
               
               
                 Selection 
                 Descriptors. The components 
               
               
                 Descriptors 
                 of a Route Selection Descriptor 
               
               
                   
                 are described in table 6.6.2.1-3. 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2-3 
               
             
            
               
                   
               
               
                 Route Selection Descriptor 
               
            
           
           
               
               
               
               
               
            
               
                 Information 
                   
                   
                 PCF permitted 
                   
               
               
                 name 
                 Description 
                 Category 
                 to modify in URSP 
                 Scope 
               
               
                   
               
               
                 Route Selection 
                 Determines the order in which 
                 Mandatory 
                 Yes 
                 UE context 
               
               
                 Descriptor 
                 the Route Selection 
                 (NOTE 1) 
               
               
                 Precedence 
                 Descriptors are to be applied. 
               
               
                 Route 
                 This part defines the route 
                 Mandatory 
               
               
                 selection 
                 selection components 
                 (NOTE 2) 
               
               
                 components 
               
               
                 SSC Mode 
                 One single value of SSC mode. 
                 Optional 
                 Yes 
                 UE context 
               
               
                 Selection 
                 (NOTE 5) 
               
               
                 Network Slice 
                 Either a single value or a list 
                 Optional 
                 Yes 
                 UE context 
               
               
                 Selection 
                 of values of S-NSSAI(s). 
                 (NOTE 3) 
               
               
                 DNN Selection 
                 Either a single value or a list 
                 Optional 
                 Yes 
                 UE context 
               
               
                   
                 of values of DNN(s). 
               
               
                 PDU Session 
                 One single value of PDU 
                 Optional 
                 Yes 
                 UE context 
               
               
                 Type Selection 
                 Session Type 
                 (NOTE 8) 
               
               
                 Non-Seamless 
                 Indicates if the traffic of the 
                 Optional 
                 Yes 
                 UE context 
               
               
                 Offload 
                 matching application is to be 
                 (NOTE 4) 
               
               
                 indication 
                 offloaded to non-3GPP access 
               
               
                   
                 outside of a PDU Session. 
               
               
                 Access Type 
                 Indicates the preferred Access 
                 Optional 
                 Yes 
                 UE context 
               
               
                 preference 
                 Type (3GPP or non-3GPP or 
               
               
                   
                 Multi-Access) when the UE 
               
               
                   
                 establishes a PDU Session for 
               
               
                   
                 the matching application. 
               
               
                 Route 
                 This part defines the Route 
                 Optional 
               
               
                 Selection 
                 Validation Criteria components 
               
               
                 Validation 
               
               
                 Criteria 
               
               
                 (NOTE 6) 
               
               
                 Time Window 
                 The time window when the 
                 Optional 
                 Yes 
                 UE context 
               
               
                   
                 matching traffic is allowed. 
               
               
                   
                 The RSD is not considered to be 
               
               
                   
                 valid if the current time is 
               
               
                   
                 not in the time window. 
               
               
                 Location 
                 The UE location where the 
                 Optional 
                 Yes 
                 UE context 
               
               
                 Criteria 
                 matching traffic is allowed. 
               
               
                   
                 The RSD rule is not considered 
               
               
                   
                 to be valid if the UE location 
               
               
                   
                 does not match the location 
               
               
                   
                 criteria. 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 PDU Session related policy information 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 PCF permitted 
                   
                   
               
               
                   
                   
                 to modify for 
                   
                 Differences 
               
               
                   
                   
                 dynamically 
                   
                 compared with 
               
               
                   
                   
                 provided 
                   
                 table 6.4, and 6.6 
               
               
                 Attribute 
                 Description 
                 information 
                 Scope 
                 in TS 23.203 [4] 
               
               
                   
               
               
                 Charging 
                 Defines the containing CHF 
                 No 
                 PDU 
                 None 
               
               
                 information 
                 address and optionally the 
                   
                 Session 
               
               
                   
                 associated CHF instance ID 
               
               
                   
                 and CHF set ID. 
               
               
                 Default charging 
                 Defines the default charging 
                 No 
                 PDU 
                 None 
               
               
                 method 
                 method far the PDU Session. 
                   
                 Session 
               
               
                 PDU Session 
                 Indicates that the “online” 
                 No 
                 PDU 
                 Added 
               
               
                 with offline 
                 charging method is never used 
                   
                 Session 
               
               
                 charging only 
                 for PCC rules in the PDU Session. 
               
               
                 Policy control 
                 Defines the event(s) that shall 
                 Yes 
                 PDU 
                 Explicitly 
               
               
                 request trigger 
                 cause a re-request of PCC 
                   
                 Session 
                 subscribed by 
               
               
                   
                 rules for the PDU Session. 
                   
                   
                 invoking 
               
               
                   
                   
                   
                   
                 Npcf_SMPolicyControl 
               
               
                   
                   
                   
                   
                 service operation 
               
               
                 Authorized QoS per 
                 Defines the authorised QoS for 
                 Yes 
                 IP-CAN 
                 Removed 
               
               
                 bearer (UE-initiated 
                 the IP-CAN bearer (QCI, GBR, 
                   
                 bearer 
               
               
                 IP-CAN bearer 
                 MBR). 
               
               
                 activation/modification). 
               
               
                 Authorized MBR per 
                 Defines the authorised MBR 
                 Yes 
                 IP-CAN 
                 Removed 
               
               
                 QCI (network initiated 
                 per QCI. 
                   
                 session 
               
               
                 IP-CAN bearer 
               
               
                 activation/modification) 
               
               
                 Revalidation time limit 
                 Defines the time period within 
                 Yes 
                 PDU 
                 None 
               
               
                   
                 which the SMF shall perform a 
                   
                 Session 
               
               
                   
                 PCC rules request. 
               
               
                 PRA Identifier(s) 
                 Defines the Presence 
                 Yes 
                 PDU 
                 None but only 
               
               
                   
                 Reporting Area(s) to monitor 
                   
                 Session 
                 applicable to PCF 
               
               
                   
                 for the UE with respect to 
               
               
                   
                 entering/leaving 
               
               
                 List(s) of Presence 
                 Defines the elements of the 
                 Yes 
                 PDU 
                 None but only 
               
               
                 Reporting Area 
                 Presence Reporting Area(s) 
                   
                 Session 
                 applicable to PCF 
               
               
                 elements (NOTE 14) 
               
               
                 Default NBIFOM 
                 The access to be used for all 
                 Yes (only at 
                 IP-CAN 
                 Removed 
               
               
                 access 
                 traffic that does not match any 
                 the addition of 
                 session 
               
               
                   
                 existing Routing Rule 
                 an access to the 
               
               
                   
                   
                 IP-CAN session) 
               
               
                 IP Index 
                 Provided to SMF to assist in 
                 No 
                 PDU 
                 Added 
               
               
                 (NOTE 11) 
                 determining the IP Address 
                   
                 Session 
               
               
                   
                 allocation method (e.g. which 
               
               
                   
                 IP pool to assign from) when a 
               
               
                   
                 PDU Session requires an IP 
               
               
                   
                 address - as defined in 
               
               
                   
                 TS 23.501 [2] clause 5.8.2.2.1. 
               
               
                 Explicitly signalled 
                 Defines a dynamically assigned 
                 No 
                 PDU 
                 Added 
               
               
                 QoS Characteristics 
                 5QI value (from the non- 
                   
                 Session 
               
               
                 (NOTE 1) 
                 standardized value range) and 
               
               
                   
                 the associated 5G QoS 
               
               
                   
                 characteristics as defined in 
               
               
                   
                 TS 23.501 [2] clause 5.7.3. 
               
               
                 Reflective QoS Timer 
                 Defines the lifetime of a UE 
                 No 
                 PDU 
                 Added 
               
               
                   
                 derived QoS rule belonging to 
                   
                 Session 
               
               
                   
                 the PDU Session. 
               
               
                 Authorized Session- 
                 Defines the Aggregate 
                 Yes 
                 PDU 
                 Modified 
               
               
                 AMBR 
                 Maximum Bit Rate for the Non- 
                   
                 Session 
               
               
                 (NOTE 2) (NOTE 3) 
                 GBR QoS Flows of the PDU 
               
               
                   
                 Session. 
               
               
                 Authorized default 
                 Defines the default 5QI and 
                 Yes 
                 PDU 
                 Modified 
               
               
                 5QI/ARP 
                 ARP of the QoS Flow 
                   
                 Session 
               
               
                 (NOTE 3) (NOTE 10) 
                 associated with the default 
               
               
                   
                 QoS rule. 
               
               
                 Time Condition 
                 Defines the time at which the 
                 No (NOTE 5) 
                 PDU 
                 Modified 
               
               
                 (NOTE 4) 
                 corresponding Subsequent 
                   
                 Session 
               
               
                   
                 Authorized Session-AMBR or 
               
               
                   
                 Subsequent Authorized default 
               
               
                   
                 5QI/ARP shall be applied. 
               
               
                 Subsequent 
                 Defines the Aggregate 
                 No (NOTE 5) 
                 PDU 
                 Modified 
               
               
                 Authorized Session- 
                 Maximum Bit Rate for the Non- 
                   
                 Session 
               
               
                 AMBR (NOTE 4) 
                 GBR QoS Flows of the PDU 
               
               
                 (NOTE 2) 
                 Session when the Time 
               
               
                   
                 Condition is reached. 
               
               
                 Subsequent 
                 Defines the default 5QI and 
                 No (NOTE 5) 
                 PDU 
                 Modified 
               
               
                 Authorized default 
                 ARP when the Time Condition 
                   
                 Session 
               
               
                 5QI/ARP (NOTE 4) 
                 is reached. 
               
               
                 (NOTE 10) 
               
               
                 Usage Monitoring 
                 Defines the information that is 
               
               
                 Control related 
                 required to enable user plane 
               
               
                 information 
                 monitoring of resources for 
               
               
                 (NOTE 12) (NOTE 13) 
                 individual applications/services, 
               
               
                   
                 groups of applications/services, 
               
               
                   
                 for a PDU Session. 
               
               
                 Monitoring key 
                 The PCF uses the monitoring 
                 No 
                 PDU 
                 None 
               
               
                   
                 key to group services that 
                   
                 Session 
               
               
                   
                 share a common allowed usage. 
                   
                 (NOTE 12) 
               
               
                 Volume threshold 
                 Defines the traffic volume value 
                 Yes 
                 Monitoring 
                 None 
               
               
                 (NOTE 7) 
                 after which the SMF shall 
                   
                 key 
               
               
                   
                 report usage to the PCF for this 
               
               
                   
                 monitoring key. 
               
               
                 Time threshold 
                 Defines the resource time 
                 Yes 
                 Monitoring 
                 None 
               
               
                 (NOTE 7) 
                 usage after which the SMF 
                   
                 key 
               
               
                   
                 shall report usage to the PCF. 
               
               
                 Monitoring time 
                 Defines the time at which the 
                 No (NOTE 6) 
                 Monitoring 
                 None 
               
               
                   
                 SMF shall reapply the Volume 
                   
                 Key 
               
               
                   
                 and/or Time Threshold. 
               
               
                 Subsequent Volume 
                 Defines the traffic volume value 
                 No (NOTE 6) 
                 Monitoring 
                 None 
               
               
                 threshold (NOTE 9) 
                 after which the SMF shall 
                   
                 Key 
               
               
                   
                 report usage to the PCF for this 
               
               
                   
                 Monitoring key for the period 
               
               
                   
                 after the Monitoring time. 
               
               
                 Subsequent Time 
                 Defines resource time usage 
                 No (NOTE 6) 
                 Monitoring 
                 None 
               
               
                 threshold (NOTE 9) 
                 after which the SMF shall 
                   
                 Key 
               
               
                   
                 report usage to the PCF for this 
               
               
                   
                 Monitoring key for the period 
               
               
                   
                 after the Monitoring time. 
               
               
                 Inactivity Detection 
                 Defines the period of time after 
                 Yes 
                 Monitoring 
                 None 
               
               
                 Time (NOTE 8) 
                 which the time measurement 
                   
                 Key 
               
               
                   
                 shall stop, if no packets are 
               
               
                   
                 received. 
               
               
                 Ethernet port 
               
               
                 management related 
               
               
                 Port number 
                 Port number for which Port 
                 Yes 
                 PDU 
                 New 
               
               
                   
                 Management Information 
                   
                 Session 
               
               
                   
                 Container is provided. 
               
               
                 Port Management 
                 Includes Ethernet port 
                 Yes 
                 PDU 
                 New 
               
               
                 Information Container 
                 management information 
                   
                 Session 
               
               
                   
               
            
           
         
       
     
     The UDM  145  is an NF that stores and manages subscriber information (UE subscription) of the user equipment  100 . The UDR  150  is an NF or database (DB) that stores and manages data. 
     The UDR  150  may store subscription information of the user equipment  100  and provide the subscription information of the user equipment  100  to the UDM  145 . In addition, the UDR  150  may store operator policy information and provide the operator policy information to the PCFs  140  and  141 . 
     The NSSF  160  may be an NF that performs a function of selecting network slice instances providing a service to the user equipment  100  or determining Network Slice Selection Assistance Information (NSSAI). 
     The AUSF  165  may be an NF that performs a function of supporting authentication for 3GPP access and non-3GPP access. 
     The AF  170  may be an NF that provides a function for a service according to the present disclosure. 
     The DN  175  may refer to a data network that may provide an operator service, Internet access, or a third party service. 
       FIG.  2    is a sequence diagram illustrating a user equipment registration procedure according to an embodiment of the present disclosure.  FIG.  2    illustrates an operation method of the user equipment  100 , the base station  110 , the AMF  120 , the UDM  145 , and the PCF  140 . 
     Referring to  FIG.  2   , in operation  210 , the user equipment  100  may configure a registration request message and transmit the same to the base station  110 . According to an embodiment, the registration request message may include a user equipment identifier (e.g., Subscription Permanent Identifier (SUPI), Subscription Concealed Identifier (SUCI), 5G Globally Unique Temporary Identifier (5G GUTI), etc.), a request slice (Requested NSSAI: slice information that the user equipment  100  desires to use by accessing a network), a UE policy container, UE policy-related information (e.g., a first PSI list (a list of PSIS) indicating the UE policy stored in the user equipment  100 ), and the like. The UE policy container may include UE policy-related information stored in the user equipment  100  (e.g., the first PSI list (a list of PSIS) indicating a UE policy stored in the user equipment  100 ). 
     In operation  212 , the base station  110  may select an AMF. For example, the base station  110  that has received the registration request message from the user equipment  100  may select an AMF to transmit the message received in operation  210 , based on at least one of the information (e.g., Requested NSSAI, user equipment identifier, etc.) received from the user equipment  100  in operation  210 . 
     In operation  214 , the base station  110  may transmit the registration request message to the AMF ( 120 ). For example, the base station  110  may transmit the registration request message to the AMF  120  selected in operation  212 . The AMF  120  may store information received from the user equipment  100 , for example, the first PSI list (a list of PSIS) indicating UE policy, which is stored in the user equipment  100 . The AMF  120  may store the first PSI list as a UE context. 
     In operation  216 , the AMF  120  may request the UDM  145  for user equipment subscription information (Subscription Data). 
     In operation  218 , the UDM  145  may transmit a response to the user equipment subscription information request to the AMF  120 . For example, the AMF  120  may obtain related information of the user equipment  100  from the UDM  145  (e.g., Access and Mobility Subscription data, SMF Selection Subscription data, UE context, subscribed DNNs, subscribed S-NSSAIs, etc.). 
     In operation  220 , the AMF  120  may perform a PCF selection procedure. For example, the AMF  120  may determine to select a PCF that supports a Data Network Name (DNN) replacement function or a URSP replacement function, based on at least one of information received from the user equipment  100 , information received from the UDM  145 , or a local policy of the AMF  120 . In addition, the AMF  120  may select a PCF that supports a DNN replacement function or a URSP replacement function. 
     In operation  222 , the AMF  120  may transmit an Npcf_AMPolicyControl_Create request message to the PCF  140 . For example, the AMF  120  may perform AM policy association establishment with the PCF  140  selected in operation  220 . 
     In operation  224 , the PCF  140  may determine a policy. For example, the PCF  140  may determine AM policy information to be provided to the AMF  120 , based on information received from the AMF  120 . 
     In operation  226 , the PCF  140  may transmit an Npcf_AMPolicyControl_Create response message to the AMF  120 . In an embodiment, the Npcf_AMPolicyControl_Create response message transmitted from the PCF  140  to the AMF  120  may include AM policy information determined by the PCF  140 . The AMF  120  may store the AM policy information received from the PCF  140 , and then use the stored AM policy in an operation and procedure of the AMF  120 . 
     In operation  228 ; the AMF  120  may transmit a Registration Accept message to the user equipment  100 . The AMF  120  may include, in the Registration Accept message, slice information (e.g., Allowed NSSAI, etc.) available to the user equipment  100  by accessing a network. 
     In operation  230 , the AMF  120  may transmit an Npcf_UEPolicyControl_Create request message to the PCF  140 . For example; the AMF  120  may perform UE policy association establishment with the PCF  140  that has established AM policy association. The Npcf_UEPolicyControl_Create request message transmitted by the AMF  120  to the PCF  140  may include at least one of a UE policy container or first PSI list information, which are received from the user equipment  100 . 
     In operation  232 , the PCF  140  may determine a policy. For example, the PCF  140  may compare the first PSI list among the information received from the AMF  120 , with the latest list of PSIs of the user equipment, which is stored in the PCF  140  and/or the UDR  150 , which, is a second PSI list. When the first PSI list does not match the second PSI list; the PCF  140  may determine that the user equipment  100  is not storing the latest UE policy information, and determine to transmit the latest UE policy information to the user equipment  100 . 
     According to another embodiment, in operation  232 , the PCF  140  may determine to update the UE policy based on the user equipment subscription information, the operator policy, and the like. The PCF  140  may determine the updated UE policy. Also, the PCF  140  may allocate a latest PSI indicating the update UE policy. The latest list of PSIs indicating the updated UE policy is referred to as the second PSI list. 
     In operation  234 , the PCF  140  may transmit an Npcf_UEPolicyControl_Create response message to the AMF  120 . In an embodiment, the Npcf_UEPolicyControl_Create response message transmitted from the PCF  140  to the AMF  120  may include the latest UE policy information of the user equipment  100 , that is, the second PSI list. The AMF  120  may store second PSI information received from the PCF  140 . For example, the AMF  120  may store the second PSI information as a UE context. 
     As described above in  FIG.  2   , the AMF  120  may store the UE policy-related information of the user equipment, for example, at least one of the first PSI list received from the user equipment  100  and the second PSI list received from the PCF  140 . 
       FIG.  3    is a sequence diagram illustrating a UE policy update procedure according to an embodiment of the present disclosure. 
     Referring to  FIG.  3   , the PCF  140  according to an embodiment of the present disclosure may update a UE policy according to various methods to be described later, and may determine to transmit the updated, latest UE policy to the user equipment  100 . 
     According to an embodiment of the present disclosure, during the registration procedure described above in  FIG.  2   , the PCF  140  may determine to transmit the latest UE policy to the user equipment  100  during the procedure for UE policy association establishment in operations  230  to  234 . For example, in operation  232 , the PCF  140  may compare the first PSI list with the second PSI list. When the first PSI list does not match the second PSI list, the PCF  140  may determine that the user equipment  100  is not storing the latest UE policy information, and determine to transmit the latest UE policy information to the user equipment  100 . In operation  234 , the second PSI list may be included in the Npcf_UEPolicyControl_Create response message transmitted by the PCF  140  to the AMF  120 . The AMF  120  may store the received second PSI list. For example, the AMF  120  may store the second PSI information as a UE context. 
     According to another embodiment, the PCF  140  may determine to transmit the latest UE policy to the user equipment  100  in operation  312 . In operation  310 , the AMF  120  may transmit an Npcf_UEPolicyControl_Update request message to the PCF  140 . The Npcf_UEPolicyControl_Update request message may include location information of the user equipment  100  (e.g., tracking area, Presence Reporting Area, etc.), PLMN information, connection state information of the user equipment  100 , and the like. In operation  312 , the PCF  140  may determine to update the UE policy based on the information received from the AMF  120 , and to transmit the updated, latest UE policy to the user equipment  100 . The PCF  140  may determine the updated UE policy and may allocate a latest PSI indicating the updated UE policy. The latest list of PSIs indicating the updated UE policy is referred to as the second PSI list. In operation  314 , the PCF  140  may transmit an Npcf_UEPolicyControl_Update response message to the AMF  120 . The Npcf_UEPolicyControl_Update response message may include the second PSI list. The AMF  120  may store the received second PSI list. For example, the AMF  120  may store the second PSI list as a UE context. 
     According to another embodiment, the PCF  140  may determine to transmit the latest UE policy to the user equipment  100  in operation  316 . For example, in operation  316 , the PCF  140  may determine to update the UE policy based on an operator policy, user equipment subscription information, and the like. The PCF  140  may determine the updated UE policy and may allocate the latest PSI indicating the updated UE policy. The latest list of PSIs indicating the updated UE policy is referred to as the second PSI list. 
     As described above, the PCF  140  may determine to update the UE policy according to various methods and transmit the updated, latest UE policy to the user equipment  100 . For convenience of description of the present disclosure, the operations of the PCF  140  in operations  232  and  312  to  316  have been described separately, but the operations of the PCF  140  may occur simultaneously. That is, the UE policy update-related decision by the PCF  140  may be determined based on one or more of information received from the user equipment  100 , information received from the AMF  120 , user equipment subscription information, and operator policy. Operations  318  to  330  described below describe a procedure for transmitting, by the PCF  140 , the updated, latest UE policy to the user equipment  100 . 
     In operation  318 , the PCF  140  may transmit a Namf_Communication_N1N2MessageTransfer message to the AMF  120 . Namf_Communication_N1N2MessageTransfer may include the UE policy of the user equipment  100  determined by the PCF  140 . In addition, Namf_Communication_N1N2MessageTransfer may include a second PSI list indicating the UE policy of the user equipment  100 . The AMF  120  may store the second PSI list received from the PCF  140 . For example, the AMF  120  may store the second PSI list as a UE context. 
     In operation  320 , when the user equipment  100  is in an idle mode, the AMF  120  may perform a Network Triggered Service Request procedure to wake up the user equipment. 
     When the user equipment is woken up in operation  320 , operation  322  may be performed. 
     When it is not possible to wake up the user equipment in operation  320 , operations  322  to  326  may be omitted, and the AMF  120  may transmit a Namf_Communication_N1N2MessageNotify message of operation  328 . The Namf_Communication_N1N2MessageNotify message may include information indicating that the user equipment  100  is not reachable or unreachable or information indicating that the user equipment  100  is not connected. Upon receiving the Namf_Communication_N1N2MessageNotify message, the PCF  140  may know that the UE policy transmitted in operation  318  has not been transmitted to the user equipment  100 . 
     In operation  322 , the AMF  120  may transmit a DL Non Access Stratum (NAS) Transport message to the user equipment  100 . The DL NAS Transport message may include the UE policy information and the second PSI list received by the AMF  120  from the PCF  140  in operation  318 . 
     In operation  324 , the user equipment  100  may store the UE policy information and the second PSI list received in operation  322 . In addition, the user equipment  100  may apply the received UE policy information. The user equipment  100  may determine when to apply the received UE policy. For example, the user equipment  100  may determine to apply the UE policy immediately upon receiving. Alternatively, the user equipment  100  may determine to apply the UE policy in an idle mode. Alternatively, the user equipment  100  may determine to apply the UE policy after one or more protocol data unit (PDU) sessions that are currently in use are ended. However, the present disclosure is not limited to the above example. 
     In operation  326 , the user equipment  100  may transmit a UL NAS Transport message to the AMF  120 . For example, after receiving the DL NAS Transport message in operation  322 , the user equipment  100  may transmit a UL NAS Transport message. The UL NAS Transport message may include information indicating that the user equipment  100  has received the UE policy. In addition, the UL NAS Transport message may include the second PSI list indicating the UE policy received by the user equipment  100 . The AMF  120  may store a PSI list received from the user equipment  120 . For example, the AMF  120  may store the PSI list as a PSI list received by the user equipment, in the UE context. 
     According to another embodiment, after applying the UE policy in operation  324 , the user equipment  100  may transmit the UL NAS Transport message in operation  326 . The UL NAS Transport message may include information indicating that the user equipment  100  has applied the UE policy. In addition, the UL NAS Transport message may include the second PSI list indicating a UE policy applied or not applied by the user equipment  100  and/or one or more PSIS among the second PSI list. The AMF  120  may store the PSI list received from the user equipment  100 . For example, the AMF  120  may store the PSI list as a PSI list, to which a policy is applied by the user equipment, in the UE context. Alternatively, the AMF  120  may store the corresponding PSI list in the UE context as a PSI list to which the user equipment does not apply a policy. 
     When the user equipment applies the received UE policy in operation  324 , the user equipment  100  may apply all the received UE policies. Alternatively, the user equipment  100  may apply some of the received UE policies, and may not apply some of the remaining UE policies. Alternatively, the user equipment  100  may not be able to apply all of the received UE policies. Accordingly, after the user equipment  100  has applied the UE policy in operation  324 , in terms of transmitting the UL NAS Transport message in operation  326 , the user equipment  100  may include, in the UL NAS Transport message, UE policy information, to which the user equipment  100  has applied a policy (e.g., one or more pieces of PSI information to which a policy is applied among the second PSI list received in operation  322 ). Alternatively, the user equipment  100  may include, in the UL NAS Transport message, UE policy information to which the user equipment  100  has failed to apply a policy (e.g., one or more pieces of PSI information to which the policy is not applied among the second PSI list received in operation  322 ). 
     In operation  328 , the AMF  120  may transmit a Namf_Communication_N1Notify message to the PCF  140 . The Namf_Communication_N1Notify message may include information indicating that the user equipment  100  has received the UE policy, information indicating that the user equipment  100  has applied the UE policy, and information indicating that the user equipment  100  has failed to apply the UE policy. In addition, the Namf_Communication_N1Notify message may include the second PSI list received from the user equipment  100  and/or one or more PSIs of the second PSI list. Upon receiving the message in operation  328 , the PCF  140  may determine whether the user equipment  100  has successfully received the latest UE policy transmitted in operation  318 , and whether or not the user equipment  100  has applied the latest UE policy. 
     In operation  330 , the PCF  140  may store, in the UDR  150 , the latest UE policy that the user equipment  100  has successfully received and applied, and the latest PSI list indicating the UE policy, that is, the second PSI list and/or at least one PSI of the second PSI list. 
       FIG.  4    is a sequence diagram illustrating a UE policy update procedure according to an embodiment of the present disclosure. 
     Referring to  FIG.  4   , in operation  410 , a change may occur in user equipment subscription information stored in the UDR  150 . 
     In operation  412 , the UDR  150  may transmit a Nudr_DM_Notify message to the PCF  140 . The Nudr_DM_Notify message may include changed user equipment subscription information. For example, the Nudr_DM_Notify message may include at least one of S-NSSAI, DNN, SSC mode, or PDU session type, to which the user equipment subscribes. 
     In operation  414 , the PCF  140  may determine to update the UE policy based on the UE subscription information received from the UDR  150 . The PCF  140  may determine the updated UE policy and may allocate the latest PSI indicating the updated UE policy. The latest list of PSIs indicating the updated UE policy may be referred to as the second PSI list. 
     In operation  416 , the PCF  140  may transmit an Npcf_UEPolicyControl_UpdateNotify request message to the AMF  120 . The Npcf_UEPolicyControl_UpdateNotify request message may include the second PSI list. The AMF  120  may store the second PSI list received from the PCF  140 . For example, the AMF  120  may store the second PSI list as a UE context. 
     In operation  418 , the AMF  120  may transmit an Npcf_UEPolicyControl_UpdateNotify response message to the PCF  140 . 
     In operation  420 , the PCF  140  may determine to transmit the updated, latest policy to the user equipment  100 . 
     In operation  422 , the PCF  140  may transmit a Namf_Communication_N1N2MessageTransfer message to the AMF  120 . The Namf_Communication_N1N2MessageTransfer may include the UE policy of the user equipment  100 , determined by the PCF  140 . In addition, Namf_Communication_N1N2MessageTransfer may include the second PSI list indicating the UE policy of the user equipment  100 . The AMF  120  may store the second PSI list received from the PCF  140 . For example, the AMF  120  may store the second PSI list as a UE context. 
     In operation  424 , when the user equipment  100  is in an idle mode, the AMF  120  may perform a Network Triggered Service Request procedure to wake up the user equipment. 
     When the user equipment is woken up in operation  424 , operation  426  may be performed. 
     When it is not possible to wake up the user equipment in operation  424 , operations  426  to  430  may be omitted, and the AMF  120  may transmit a Namf_Communication_N1N2MessageNotify message of operation  432 . The Namf_Communication_N1N2MessageNotify message may include information indicating that the user equipment  100  is not reachable or unreachable or information indicating that the user equipment  100  is not connected, Upon receiving the Namf_Communication_N1N2MessageNotify message, the PCF  140  may know that the UE policy transmitted in operation  422  has not been transmitted to the user equipment  100 . 
     In operation  426 , the AMF  120  may transmit a DL NAS Transport message to the user equipment  100 . The DL NAS Transport message may include the UE policy information and the second PSI list received by the AMF  120  from the PCF  140  in operation  422 . 
     In operation  428 , the user equipment  100  may store the UE policy information and the second PSI list received in operation  426 . In addition, the user equipment  100  may apply the received UE policy information. The user equipment  100  may determine when to apply the received UE policy. For example, the user equipment  100  may determine to apply the UE policy immediately upon receiving. Alternatively, the user equipment  100  may determine to apply the UE policy in an idle mode. Alternatively, the user equipment  100  may determine to apply the UE policy after one or more PICU sessions that are currently in use are ended. However, the present disclosure is not limited to the above example. 
     In operation  430 , the user equipment  100  may transmit a UL NAS Transport message to the AMF  120 . For example, after receiving the DL NAS Transport message in operation  426 , the user equipment  100  may transmit a UL NAS Transport message. The UL NAS Transport message may include information indicating that the user equipment  100  has received the UE policy. In addition, the UL NAS Transport message may include the second PSI list indicating the UE policy received by the user equipment  100 . The AMF  120  may store the PSI list received from the user equipment  100 . For example, the AMF  120  may store the PSI list as a PSI list received by the UE, in the UE context. 
     According to another embodiment, after applying the UE policy in operation  428 , the user equipment  100  may transmit the UL NAS Transport message in operation  430 . The UL NAS Transport message may include information indicating that the user equipment  100  has applied the UE policy. In addition, the UL NAS Transport message may include the second PSI list indicating a UE policy applied or not applied by the user equipment  100  and/or one or more PSIs of the second PSI list. The AMF  120  may store the PSI list received from the user equipment  100 . For example, the AMF  120  may store the PSI list as a PSI list, to which a policy is applied by the user equipment, in the UE context. Alternatively, the AMF  120  may store the corresponding PSI list in the UE context as a PSI list to which the user equipment does not apply a policy. 
     When the user equipment applies the received UE policy in operation  428 , the user equipment  100  may apply all the received UE policies. Alternatively, the user equipment  100  may apply some of the received UE policies, and may not apply some of the remaining UE policies. Alternatively, the user equipment  100  may not be able to apply all of the received UE policies. Accordingly, after the user equipment  100  has applied the UE policy in operation  428 , in terms of transmitting the UL NAS Transport message in operation  430 , the user equipment  100  may include, in the UL NAS Transport message. UE policy information, to which the user equipment  100  has applied a policy (e.g., one or more pieces of PSI information to which a policy is applied among the second PSI list received in operation  426 ). Alternatively, the user equipment  100  may include, in the UL NAS Transport message, UE policy information to which the user equipment  100  has failed to apply a policy (e.g., one or more pieces of PSI information to which the policy is not applied among the second PSI list received in operation  426 ). 
     In operation  432 , the AMF  120  may transmit a Namf_Communication_N1Notify message to the PCF  140 . The Namf_Communication_N1Notify message may include information indicating that the user equipment  100  has received the UE policy, information indicating that the user equipment  100  has applied the UE policy, and information indicating that the user equipment  100  has failed to apply the UE policy. In addition, the Namf_Communication_N1Notify message may include the second PSI list received from the user equipment  100  and/or one or more PSIs among the second PSI list, Upon receiving the message in operation  432 , the PCF  140  may determine whether the user equipment  100  has successfully received the latest UE policy transmitted in operation  422  and whether or not the user equipment  100  has applied the latest UE policy. 
     In operation  434 , the PCF  140  may store, in the UDR  150 , the latest UE policy that the user equipment  100  has successfully received and applied, and a latest PSI list indicating the UE policy, that is, the second PSI list and/or one or more PSIs among the second PSI list. 
       FIG.  5    is a sequence diagram illustrating a policy update procedure according to an embodiment of the present disclosure. 
     Referring to  FIG.  5   , an event of the PCF  140  (a PCF event) may occur in operation  510 . For example, after transmitting the latest UE policy to the user equipment  100  in operation  234  of  FIG.  2   , operation  314 , operation  318  of  FIG.  3   , operation  416  or  422  of  FIG.  4   , the PCF  140  may perform operations subsequent to operation  512 . Alternatively, for example, as described above with reference to  FIGS.  3  to  4   , the PCF  140  may know that the user equipment  100  failed to receive the latest UE policy transmitted to the user equipment  100  or the user equipment  100  failed to apply at least some of the latest UE policies. That is, the PCF  140  may know that a mismatch has occurred between the user equipment subscription information stored in the UDR  150  and at least some of the UE policies applied by the user equipment  100 . For example, the user equipment subscription information stored in the UDR  150  may include DNN A as a subscribed DNN, but the user equipment  100  may not apply DNN A as a UE policy. Alternatively, while DNN B is not included as a subscribed DNN in the user equipment subscription information stored in the UDR  150 , the user equipment  100  may apply DNN B as a UE policy. 
     In operation  512 , the PCF  140  may make a policy decision for resolving the mismatch between the user equipment subscription information and the UE policy application determined in operation  510 . [Table 4] illustrates examples of policies determined by the PCF  140  in operation  512 . 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Policy control information 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 PCF permitted 
                   
               
               
                   
                   
                   
                 to modify in a 
               
               
                 Information 
                   
                   
                 UE context in 
               
               
                 name 
                 Description 
                 Category 
                 the AMF 
                 Scope 
               
               
                   
               
               
                 DNN replacement 
                 Defines if a UE 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 of unsupported 
                 requested unsupported 
                 (NOTE 6) 
               
               
                 DNNs 
                 DNN is requested 
               
               
                   
                 for replacement by PCF 
               
               
                 List of S-NSSAIs 
                 Defines the list of 
                 Conditional 
                 Yes 
                 UE context 
               
               
                   
                 S-NSSAIs containing 
                 (NOTE 6) 
               
               
                   
                 DNN candidates for 
                 (NOTE 7) 
               
               
                   
                 replacement by PCF 
               
               
                 Per S-NSSAI: 
                 Defines UE requested 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 List of DNNs 
                 DNN candidates for 
                 (NOTE 6) 
               
               
                   
                 replacement by PCF 
               
               
                 For each DNN in 
                 Indicates the allowed 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 S-NSSAI level: 
                 SSC modes for the DNN, 
               
               
                 SSC modes 
                 S-NSSAI. 
               
               
                 For each DNN in 
                 Indicates the allowed 
                 Conditional 
                 Yes 
                 UE context 
               
               
                 S-NSSAI level: 
                 PDU Session Types 
               
               
                 PDU Session Types 
                 (IPv4, IPv6, IPv4v6, 
               
               
                   
                 Ethernet, and 
               
               
                   
                 Unstructured) for the 
               
               
                   
                 DNN, S-NSSAI. 
               
               
                   
               
            
           
         
       
     
     In operation  514 , the PCF  140  may transmit an Npcf_AMPolicyControl_UpdateNotify Request message and/or an Npcf_UEPolicyControl_UpdateNotify Request message to the AMF  120 . The Npcf_AMPolicyControl_UpdateNotify Request message and/or the Npcf_UEPolicyControl_UpdateNotify Request message may include the policies determined by the PCF  140  in operation  512 . 
     In operation  516 , the AMF  120  may transmit an Npcf_AMPolicyControl_UpdateNotify Response message and/or an Npcf_UEPolicyControl_UpdateNotify Response message to the PCF  140 . 
     In operation  518 , the AMF  120  may apply the policies received from the PCF  140  in operation  514 . The policy application method in operation  518  will be described in detail with reference to  FIG.  7   . 
       FIG.  6    is a sequence diagram illustrating a policy update procedure according to an embodiment of the present disclosure. 
     Referring to  FIG.  6   , an event of the AMF  120  (an AMF event) may occur in operation  610 . For example, for example, as described above with reference to  FIGS.  3  to  4   , the AMF  120  may know that the user equipment  100  failed to receive the latest UE policy transmitted to the user equipment  100  or the user equipment  100  failed to apply at least some of the latest UE policies, That is, the AMF  120  may know that a mismatch has occurred between the user equipment subscription information stored in the UDR  150  and the UE policies applied by the user equipment  100 . For example, the user equipment subscription information stored in the UDR  150  may include DNN A as a subscribed DNN, but the user equipment  100  may not apply DNN A as a UE policy. Alternatively, while DNN B is not included as a subscribed DNN in the user equipment subscription information stored in the UDR  150 , the user equipment  100  may apply DNN B as a UE policy. 
     In operation  612 , the AMF  120  may transmit an Npcf_AMPolicyControl_Update Request message and/or an Npcf_UEPolicyControl_Update Request message to the PCF  140  in order to resolve the mismatch between the user equipment subscription information and the UE policy application, determined in operation  610 . The Npcf_AMPolicyControl_Update Request message and/or the Npcf_UEPolicyControl_Update Request message may include information indicating the mismatch between user equipment subscription information and the UE policy application and/or information requesting URSP replacement. 
     In operation  614 , the PCF  140  may make a policy decision for resolving the mismatch between user equipment subscription information and the UE policy application. [Table 4] shows examples of the policies determined by the PCF  140  in operation  512 . 
     In operation  616 , the PCF  140  may transmit an Npcf_AMPolicyControl_Update Response message and/or an Npcf_UEPolicyControl_Update Response message to the AMF  120 . The Npcf_AMPolicyControl_Update Response message and/or the Npcf_UEPolicyControl_Update Response message may include the policies determined by the PCF  140  in operation  614 . 
     In operation  618 , the AMF  120  may apply the policies received from the PCF  140  in operation  616 . The policy application method in operation  618  will be described in detail with reference to  FIG.  7   . 
       FIG.  7    is a sequence diagram illustrating a PDU session establishment procedure according to an embodiment of the present disclosure.  FIG.  7    illustrates an operating method of the user equipment  100 , the base station  110 , the AMF  120 , the SMF  135 , the PCFs  140 ,  141 , and the UDM  145 , In an embodiment, the PCFs  140 ,  141  may be divided into the PCF  140  responsible for Access and Mobility (AM) policy and UE policy and the PCF  141  for Session Management (SM) policy. The PCF  140  and the PCF  141  may be logically or physically separated NFs or may be logically or physically one single NF. 
     According to an embodiment of the present disclosure, in operation  710 , the user equipment  100  may transmit a PDU Session Establishment Request message to the AMF  120 , The PDU Session Establishment Request message may include at least one among DNN, S-NSSAI, SSC mode, and PDU session type determined by the user equipment  100  based on the UE policy applied by the user equipment  100  by using the method described with reference to  FIGS.  3  to  4   . In addition, the PDU Session Establishment Request message may include a PSI referred by the user equipment  100  to determine the DNN, S-NSSAI, SSC mode, PDU session type, etc, determined by the user equipment  100  based on the UE policy applied by the user equipment  100 . 
     The AMF  120  may compare the PSI list stored in the AMF  120  with the PSI received from the user equipment  100  in operation  710 . 
     When the PSI received in operation  710  is included in the PSI list stored in the AMF  120  (the latest PSI list), the AMF  120  may know that the user equipment  100  has applied a valid UE policy, and perform operation  712  and subsequent operations. 
     When the PSI received in operation  710  is a value that is not included in the PSI list stored in the AMF  120  (the latest PSI list), the AMF  120  may know that the user equipment  100  has applied an invalid UE policy and reject the request from the user equipment in operation  710 . That is, the AMF  120  may transmit a PDU Session Establishment Reject message to the user equipment  100 . The PDU Session Establishment Reject message may include a cause value indicating a reason the request was rejected, and the cause value may include a value indicating that the user equipment  100  did not use a valid UE policy (e.g., PSI is not valid, not valid). PSI, etc.). Upon receiving the PDU Session Establishment Reject message, the user equipment  100  may know the reason for rejection based on the cause value included in the received message. For example, when the cause value includes a value indicating that the user equipment  100  did not use a valid UE policy, the user equipment  100  may determine that that the UE policy that is currently used by the user equipment  100  is not the latest UE policy, and may perform a user equipment registration procedure in order to receive the latest UE policy. Alternatively, the user equipment  100  may apply a UE policy that has been received in operation  322  of  FIG.  3    or in operation  426  of  FIG.  4    but has not yet been applied. The user equipment  100  may perform the registration procedure to receive the latest UE policy or, after applying the previously received UE policy, may perform the PDU session establishment procedure of  FIG.  7    again based on the applied latest UE policy. 
     According to another embodiment of the present disclosure, in operation  710 ; the user equipment  100  may transmit the PDU Session Establishment Request message to the AMF  120 . The PDU Session Establishment Request message may include at least one among DNN, S-NSSAI, SSC mode, and PDU session type determined by the user equipment  100  based on the UE policy applied by the user equipment  100  by using the method described with reference to  FIGS.  3  to  4   . 
     The AMF  120  may determine whether to carry out URSP replacement, based on at least one of information received from the user equipment  100  in operation  710 , information received from the PCF  140  in operation  514  of  FIG.  5   , information received from the PCF  140  in operation  616  of  FIG.  6   , local configuration information of the AMF  120 , or mobile operator policy information. For example, when the AMF  120  has received the policy illustrated in [Table 4] from the PCF  140  in operation  514  of  FIG.  5    and/or operation  616  of  FIG.  6   , and at least one of the DNN S-NSSAI, SSC mode, or PDU session type received from the user equipment  100  in operation  710  is included in the policy illustrated in [Table 4], the AMF  120  may determine to perform URSP replacement. That is, the policy received from the PCF  140  in operation  514  of  FIG.  5    and/or operation  616  of  FIG.  6    may include UE policy-related information which is transmitted by the PCF  140  to the user equipment  100 , but which the user equipment  100  failed to receive or apply. For example, the corresponding policy may include a previous UE policy corresponding to the latest UE policy which the user equipment  100  failed to apply. Accordingly, at least one of DNN, S-NSSAI, SSC mode, or PDU session type being received from the user equipment  100  and included in the corresponding policy received from the PCF  140  may indicate that the user equipment  100  used the previous UE policy instead of using the latest UE policy. The AMF  120  may determine to perform URSP replacement because the user equipment  100  did not use the latest UE policy. 
     According to an embodiment, the AMF  120  that has determined to perform the URSP replacement may perform operation  712  described below, to request the PCF  140  for the URSP replacement, the PCF  140  having established AM policy association or UE policy association with the AMF  120 . 
     In operation  712 , the AMF  120  may transmit an Npcf_AMPolicyControl_Update request message and/or an Npcf_UEPolicyControl_Update request message to the PCF  140 . The Npcf_AMPolicyControl_Update request message or the Npcf_UEPolicyControl_Update request message may include at least one of a requested DNN, a requested S-NSSAI, a requested SSC mode, or a requested PDU session type received from the user equipment  100  in operation  710 . 
     In operation  714 , the PCF  140  may determine a policy. For example, the PCF  140  may determine a URSP replacement policy based on the information received from the AMF  120 , local configuration information of the PCF  140 , operator policy information, the latest UE policy of the user equipment  100 , determined in operation  232  of  FIG.  2   , operation  312  of  FIG.  3   , and/or operations  414  to  420  of  FIG.  4   . For example, the PCF  140  may determine a selected DNN to replace the requested DNN. Alternatively, the PCF  140  may determine a selected S-NSSAI to replace the requested S-NSSAI. Alternatively, the PCF  140  may determine a selected SSC mode to replace the requested SSC mode. Alternatively, the PCF  140  may determine a selected PDU session type to replace the requested PDU session type. The selected DNN, selected S-NSSAI, selected SSC mode, and selected PDU session type may be information included in the latest UE policies determined by the PCF  140  for the user equipment  100 . 
     In operation  716 , the PCF  140  may transmit an Npcf_AMPolicyControl_Update response message and/or an Npcf_UEPolicyControl_Update response message to the AMF  120 . The Npcf_AMPolicyControl_Update response message and/or the Npcf_UEPolicyCtonrol_Update response message may include at least one of the selected DNN, selected S-NSSAI, selected SSC mode, or selected PDU session type determined by the PCF  140  in operation  714 . The AMF  120  that has received the Npcf_AMPolicyControl_Update response message and/or the Npcf_UEPolicyCtonrol_Update response message may store the information received from the PCF  140 . For example, the AMF  120  may store the information in association with a PDU session (for example, referred to as a PDU session ID). 
     In operation  718 , the AMF  120  may select an SMF. For example, the AMF  120  may process a PDU session establishment by using information received from the PCF  140  (e.g., selected DNN, selected S-NSSAI, selected SSC mode, selected PDU session type) instead of information received from the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type). For example, the AMF  120  may select an SMF supporting the selected DNN. 
     In operation  720 , the AMF  120  may transmit a Nsmf_PDUSession_CreateSMContext Request message to the selected SMF  135 . The Nsmf_PDUSession_CreateSMContext Request message may include at least one of information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type), information determined by the PCF  140  (e.g., selected DNN, selected S-NSSAI), selected SSC mode, selected PDU session type). The information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type) may be information included in the PDU Session Establishment Request included in an SM Container included in the Nsmf_PDUSession_CreateSMContext Request or a Nsmf_PDUSession_UpdateSMContext Request message in operation  720 . The information determined by the PCF  140  (e.g., selected DNN, selected S-NSSAI, selected SSC mode, selected PDU session type) may be information included in the Nsmf_PDUSession_CreateSMContext Request to Nsmf_PDUSession_UpdateSMContext Request message of operation  720 . The SMF  135  may proceed with the PDU session establishment procedure as follows by using the information received from the AMF  120 . 
     In operation  722 , the SMF  135  may obtain Session Management Subscription Data from the UDM  145 . The SMF  135  may authenticate a PDU session establishment request based on the information received from the AMF  120  and the subscription data obtained from the UDM  145 . 
     The SMF  135  may proceed with a subsequent PDU session establishment procedure based on the information received from the AMF  120 . The information received from the AMF  120  may include at least one of the information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type) and the information determined by the PCF  140  (e.g., selected DNN, selected S-NSSAI, selected SSC mode, selected PDU session type), In this case, the SMF  135  may proceed with the subsequent PDU session establishment procedure based on the information received from the AMF  120 . 
     The information received from the AMF  120  may include both the information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type) and the information determined by the PCF  140  (e.g., selected DNN, selected S-NSSAI, selected SSC mode, selected PDU session type), In this case, among the information received from the AMF  120 , the SMF  135  may determine priorities of the information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type) and the information determined by the PCF  140  (e.g., selected DNN, selected S-NSSAI), selected SSC mode, and selected PDU session type). The SMF  135  may proceed with, based on the priority determination, the subsequent PDU session establishment procedure by using at least one of the information requested by the user equipment  100  or the information determined by the PCF  140 . 
     According to an embodiment, the SMF  135  may determine priorities based on an operator policy (local policy) configured in the SMF  135 . For example, the SMF  135  may proceed with the subsequent PDU session establishment procedure by using the information determined by the PCF  140  according to the operator policy. Alternatively, for example, the SMF  135  may proceed with the subsequent PDU session establishment procedure by using the information requested by the user equipment  100  according to the operator policy. 
     According to another embodiment, the SMF  135  may determine priorities based on the information received from the UDM  145  in operation  722  or the information received from the AMF  120  in operation  720 . For example, the subscription data received from the UDM  145  in operation  722  may include an indicator indicating to use user equipment-requested information or an indicator indicating to use network (e.g., PCF, AMF, etc.) determination information. Alternatively, for example, the message received from the AMF  120  in operation  720  may include an indicator indicating to use user equipment-requested information or an indicator to use network (e.g., PCF, AMF, etc.) determination information. When receiving, from the AMF  120 , an indicator indicating to use the user equipment-requested information or an indicator to use the network (e.g., PCF, AMF, etc.) determination information decision information, the SMF  135  may determine priorities based on at least one of the operator policy configured in the AMF  120 , the subscription data received by the AMF  120  from the UDM  145 , or policy information received by the AMF  120  from the PCF  140 . The operator policy configured in the AMF  120  may include priority between the user equipment-requested information and the network (e.g., PCF, AMF, etc.) determination information. The subscription data received by the AMF  120  from the UDM  145  or the policy information received by the AMF  120  from the PCF  140  may include an indicator indicating to use user equipment-requested information or an indicator indicating to use network (e.g., PCF, AMF, etc.) determination information. 
     According to another embodiment, the SMF  135  may determine to preferentially use information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type). The SMF  135  may perform, based on the priority determination, a subsequent PDU session establishment procedure by using the information requested by the user equipment  100 . 
     According to another embodiment, the SMF  135  may determine to preferentially use the information determined by the PCF  140  (e.g., selected DNN, selected S-NSSAI, selected SSC mode, selected PDU session type). The SMF  135  may perform, based on the priority determination, a subsequent PDU session establishment procedure by using information determined by the PCF  140 . 
     According to an embodiment of the present disclosure, the information received by the SMF  135  from the AMF  120  may include DNN A as a requested DNN and DNN B as a selected DNN. Also, a subscribed DNN of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include DNN A but include DNN B. In this case, the SMF  135  may determine that the DNN requested by the user equipment is not included the user equipment subscription information, but the DNN replaced by the PCF  140  is included in the user equipment subscription information, and perform a subsequent procedure by using the DNN replaced by the PCF  140 . 
     According to another embodiment, the information received by the SMF  135  from the AMF  120  may include DNN A as a requested DNN and DNN B as a selected DNN. Also, a subscribed DNN of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include DNN A but include DNN B. The SMF  135  may perform a subsequent PDU session establishment procedure by using at least one of information requested by the user equipment  100  or information determined by the PCF  140 , based on priorities of the information requested by the user equipment  100  (requested DNN) and the information determined by the PCF  140  (selected DNN). For example, when it is determined to use the information requested by the user equipment  100 , because DNN A, which is the requested DNN, is not included in the user equipment subscription information, the SMF  135  may determine that the request is not a valid request, and determine to reject the PDU session establishment request. Alternatively, for example, when it is determined to use the information determined by the PCF  140 , because DNN B, which is the selected DNN, is included in the user equipment subscription information, the SMF  135  may determine that the request is a valid request, and determine to accept the PDU session establishment request. 
     According to an embodiment of the present disclosure, the information received by the SMF  135  from the AMF  120  may include S-NSSAI A as requested S-NSSAI and S-NSSAI B as selected S-NSSAI. In addition, the subscribed S-NSSAI of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include S-NSSAI A, but may include S-NSSAI B. In this case, the SMF  135  may determine that the S-NSSAI requested by the user equipment is not included the user equipment subscription information, but the S-NSSAI replaced by the PCF  140  is included in the user equipment subscription information, and perform a subsequent procedure by using the S-NSSAI replaced by the PCF  140 . 
     According to another embodiment, the information received by the SMF  135  from the AMF  120  may include S-NSSAI A as requested S-NSSAI and S-NSSAI B as selected S-NSSAI. Also, subscribed S-NSSAI of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include from the S-NSSAI A but include S-NSSAI B. The SMF  135  may perform a subsequent PDU session establishment procedure by using at least one of information requested by the user equipment  100  or information determined by the PCF  140 , based on the priority of the information requested by the user equipment  100  (requested S-NSSAI) and the information determined by the PCF  140  (selected S-NSSAI). For example, when the user equipment  100  has determined to use the requested information, because S-NSSAI A, which is the requested S-NSSAI, is not included in the user equipment subscription information, the SMF  135  may determine that the request is not a valid request, and determine to reject the PDU session establishment request. Alternatively, for example, when the PCF  140  has determined to use the determined information, because S-NSSAI B, which is the selected S-NSSAI, is included in the user equipment subscription information, the SMF  135  may determine that the request is a valid request, and determine to accept the PDU session establishment request. 
     According to an embodiment of the present disclosure, the information received by the SMF  135  from the AMF  120  may include SSC mode A as a requested SSC mode and S-NSSAI B as a selected SSC mode. Also, a subscribed SSC mode of user equipment subscription information received by the SMF  135  from the UDM  145  does not include SSC mode A but may include SSC mode B. In this case, the SMF  135  may determine that the SSC mode requested by the user equipment is not included in the user equipment subscription information, but the SSC mode replaced by the PCF  140  is included in the user equipment subscription information, and perform a subsequent procedure by using the SSC mode replaced by the PCF  140 . 
     According to another embodiment, the information received by the SMF  135  from the AMF  120  may include SSC mode A as the requested SSC mode and S-NSSAI B as the selected SSC mode. Also, a subscribed SSC mode of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include SSC mode A but may include SSC mode B. The SMF  135  may perform a subsequent PDU session establishment procedure by using at least one of information requested by the user equipment  100  or information determined by the PCF  140 , based on the priority of the information requested by the user equipment  100  (requested SSC mode) and the information determined by the PCF  140  (selected SSC mode). For example, when it is determined to use the information requested by the user equipment  100 , because SSC mode A, which is the requested SSC mode, is not included in the user equipment subscription information, the SMF  135  may determine that the request is not a valid request, and determine to reject the PDU session establishment request. Alternatively, for example, when it is determined to use the information determined by the PCF  140 , because SSC mode B, which is the selected SSC mode, is included in the user equipment subscription information, the SMF  135  may determine that the request is a valid request, and determine to accept the PDU session establishment request. 
     According to an embodiment of the present disclosure, the information received by the SMF  135  from the AMF  120  may include PDU session type A as a requested PDU session type and PDU session type B as a selected PDU session type. Also, the subscribed PDU session type of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include PDU session type A, but may include PDU session type B. In this case, the SMF  135  may determine that the PDU session type requested by the user equipment is not included in the user equipment subscription information, but the PDU session type replaced by the PCF  140  is included in the user equipment subscription information, and may perform a subsequent procedure by using the PDU session type replaced by the PCF  140 . 
     According to another embodiment, the information received by the SMF  135  from the AMF  120  may include PDU session type A as the requested PDU session type and PDU session type B as the selected PDU session type. In addition, the subscribed PDU session type of the user equipment subscription information received by the SMF  135  from the UDM  145  does not include PDU session type A, but may include PDU session type B. The SMF  135  may perform a subsequent PDU session establishment procedure by using at least one of information requested by the user equipment  100  or information determined by the PCF  140 , based on the priority of the information requested by the user equipment  100  (requested PDU session type) and the information determined by the PCF  140  (selected PDU session type), For example, when it is determined to use the information requested by the user equipment  100 , because PDU session type A, which is the requested PDU session type, is not included in the user equipment subscription information, the SMF  135  may determine that the request is not a valid request, and determine to reject the PDU session establishment request. Alternatively, for example, when it is determined to use the information determined by the PCF  140 , because the PDU session type B, which is the selected PDU session type, is included in the user equipment subscription information, the SMF  135  may determine that the request is a valid request, and may determine to accept the PDU session establishment request. 
     In operation  724 , the SMF  135  may transmit an Nsmf_PDUSession_CreateSMContext Response message to the AMF  120 . 
     In operation  726 , the SMF  135  may select a PCF for SM policy. 
     In operation  728 , the SMF  135  may perform an S0M policy association establishment with the selected PCF  140 . 
     In operation  730 , the SMF  135  may select an UPF. For example, the SMF  135  may select an UPF based on at least one of the selected DNN, selected S-NSSAI, selected SSC mode, or selected PDU session type replaced by the PCF  140 . The SMF  135  may establish an N4 session with the selected UPF  130 . 
     In operation  732 , the SMF  135  may perform an SM policy association establishment with the PCF  140 . 
     In operation  734 , the SMF  135  may transmit a Namf_Communication_N1N2MessageTransfer Request message to the AMF  120 . The Namf_Communication_N1N2MessageTransfer Request message may include a PDU Session Establishment Accept message. The PDU Session Establishment Accept message may include information requested by the user equipment (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type). 
     In operation  736 , the AMF  120  may transmit an N2 PDU Session Request message to the base station  110 . The N2 PDU Session Request message may include a PDU Session Establishment Accept message received by the AMF  120  from the SMF  135 , 
     In operation  738 , the base station  110  may perform AN-specific resource setup with the user equipment  100 . The base station  110  may transmit an RRC message to the user equipment  100  for AN-specific resource setup. Here, the RRC message transmitted by the base station  110  to the user equipment  100  for AN-specific resource setup may include a PDU Session Establishment Accept message received by the base station  110  from the AMF  120 . 
     The PCF  140  according to an embodiment of the present disclosure may determine to no longer apply the policy being applied to resolve the mismatch between the use equipment subscription information and the UE policy application. 
     The PCF  140  may receive UE policy information (e.g., a PSI list) currently applied by the user equipment  100 , from the AMF  120  in operation  230  of  FIG.  2    or operation  310  of  FIG.  3   . The PCF  140  may compare the user equipment information stored in the PCF  140  (e.g., a PSI list indicating the latest UE policy information of the user equipment  100 ) or user equipment information received from the UDR  150  (e.g., a PSI list indicating the latest UE policy information of the user equipment  100 ) with the UE policy information that is received from the AMF  120  and is currently applied by the user equipment  100  (e.g., a PSI list indicating the UE policy information that the user equipment  100  is currently applying). When the user equipment information stored in the PCF  140  (e.g., a PSI list indicating the latest UE policy information of the user equipment  100 ) or the user equipment information received from the UDR  150  (e.g., a PSI list indicating the latest UE policy information of the user equipment  100 ) is the same as the UE policy information that is received from the AMF  120  and is currently applied by the user equipment  100  (e.g., a PSI list indicating the UE policy information that the user equipment  100  is currently applying), the PCF  140  may determine that the user equipment  100  is currently applying the latest UE policy information. 
     In addition, the PCF  140  may determine, based on the information stored in the PCF  140  (e.g., user equipment context information stored in the PCF  140 , etc.), whether the policies shown in [Table 4] (e.g., referred to as SMF selection management policies) are currently applied for the user equipment  100 . 
     When it is determined that the user equipment  100  is applying the latest UE policy information in a state in which the policies shown in [Table 4] are currently being applied for the user equipment  100 , the PCF  140  may determine that the mismatch between the user equipment subscription information and the UE policy application has been resolved. Accordingly, the PCF  140  may determine to no longer apply the policies shown in [Table 4] that are being applied to resolve the mismatch between the UE subscription information and the UE policy application. 
     The PCF  140  may transmit the message of operation  514  of  FIG.  5    to the AMF  120  to update access and mobility related policy information so that the currently applied policies shown in [Table 4] are no longer applied. For example, the message of operation  514  of  FIG.  5    may include an indicator indicating that the policies shown in [Table 4] (e.g., referred to the SMF selection management policies) are not applied. Alternatively, for example, the message of operation  514  of  FIG.  5    may not include the policies shown in [Table 4] (e.g., referred to as the SMF selection management policies). 
     Upon receiving the message of operation  514  of  FIG.  5   , the AMF  120  may determine, based on the received message, that the policies shown in [Table 4] currently being applied for the user equipment  100  are no longer applied. For example, when the message of operation  514  of  FIG.  5    includes an indicator indicating that the policies shown in [Table 4] (e.g., referred to as the SMF selection management policy) are not applied, the AMF  120  may determine, based on the received indicator, that the policies shown in [Table 4] are no longer applied. Alternatively, for example, when the policies shown in [Table 4] (e.g., referred to as the SMF selection management policy) are not included in the message of operation  514  of  FIG.  5   , the AMF  120  may determine, based on the received message not including the policies shown in [Table 4], that the policies shown in [Table 4] are no longer applied. 
     The AMF  120  may update Access and Mobility related policy information which is being applied to the user equipment  100 , based on the received message of operation  514  of  FIG.  5   . The AMF  120  may not apply the policies shown in [Table 4]. Then, when the AMF  120  receives the PDU Session Establishment Request message from the user equipment  100  in operation  710  of  FIG.  7   , as the policies shown in [Table 4] are not being applied for the user equipment  100 , operations  712  to operation  716  may be omitted. That is, the AMF  120  and the SMF  135  may perform the PDU session establishment procedure illustrated in  FIG.  7    by using the information requested by the user equipment  100  (e.g., requested DNN, requested S-NSSAI, requested SSC mode, requested PDU session type). 
       FIG.  8    is a block diagram illustrating a structure of a user equipment according to an embodiment of the present disclosure. 
     As illustrated in  FIG.  8   , the user equipment  100  of the present disclosure may include a processor  830 , a transceiver  810 , and a memory  820 . Components of the user equipment  100  are, however, not limited thereto. For example, the user equipment  100  may include more or fewer elements than described above. In addition, the processor  830 , the transceiver  810 , and the memory  820  may be implemented in the form of a single chip. 
     According to an embodiment, the processor  830  may control a series of processes in which the user equipment  100  may operate according to the embodiment of the present disclosure described above. For example, in the wireless communication system according to an embodiment of the present disclosure, components of the user equipment  100  may be controlled to provide a service requested by the user equipment  100 . The processor  830  may be provided in plurality, and the processor  830  may perform an operation for providing a service, according to the present disclosure described above, by executing a program stored in the memory  820 . 
     The transceiver  810  may transmit or receive signals with the base station. A signal transmitted or received to or from a base station may include control information and data. The transceiver  810  may include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for performing low-noise amplification on the received signal and down-converting the received signal. This is merely an example, and the elements of the transceiver  810  are not limited to the RF transmitter and RF receiver. In addition, the transceiver  810  may receive a signal via a radio channel and output the same to the processor  830 , and transmit the signal output from the processor  830 , via a radio channel. 
     According to an embodiment, the memory  820  may store program and data required for operation of the user equipment  100 . In addition, the memory  820  may store control information or data included in a signal transmitted or received by the user equipment  100 . The memory  820  may include a storage medium such as ROM, RAM, a hard disk, CD-ROM, and DVD, or a combination of storage mediums. Also, the memory  820  may refer to a plurality of memories. According to an embodiment, the memory  820  may store a program for performing a method of providing a service requested by the user equipment  100  in a wireless communication system, which are the embodiments of the present disclosure described above. 
       FIG.  9    is a block diagram illustrating a structure of a core network entity according to an embodiment of the present disclosure. 
       FIG.  9    is a block diagram illustrating a structure of a core network entity in a wireless communication system, according to an embodiment of the present disclosure. The term ‘unit’, ‘ . . . er(or)’ used herein refers to a unit for processing at least one function or operation, and may be implemented by hardware or software or a combination of hardware and software. According to an embodiment, the core network entity may include the AMF  120 , the SMF  135 , the PCF  140 , or the UDM  145 , but is not limited thereto. 
     Referring to  FIG.  9   , the core network entity may include the transceiver  910 , the memory  920 , and the processor  930 . 
     The transceiver  910  may provide an interface for performing communication with other devices in a network. That is, the transceiver  910  may convert a bit string transmitted from the core network entity to another device, into a physical signal, and convert a physical signal received from another device, into a bit string. That is, the transceiver  910  may transmit or receive a signal. Accordingly, the transceiver  910  may be referred to as a modem, a transmitter, a receiver, a communication unit, or a communication module. Here, the transceiver  910  may allow a core network entity to communicate with other apparatuses or systems via a backhaul connection (e.g., wired backhaul or wireless backhaul), or other connection methods or networks. 
     The memory  920  may store data such as a default program, an application program, or configuration information for operating the core network entity. The memory  920  may be configured with a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In particular, the memory  920  may provide stored data according to a request from the processor  930 . 
     The processor  930  may control overall operations of the core network entity. For example, the processor  930  may transmit or receive a signal via the transceiver  930 . Furthermore, the processor  930  may write or read data to or from the memory  920 . For this purpose, the processor  930  may include at least one processor. The processor  930  may control the core network entity to perform the operations according to an embodiment to be described below. For example, the processor  930  may control the components of the core network entity such that the components perform the method of providing a service requested by the user equipment, according to the present disclosure. 
       FIG.  10    is a flowchart of an operating method of a user equipment, according to an embodiment of the present disclosure. 
     Referring to  FIG.  10   , in operation  1010 , the user equipment may transmit, to a base station, a registration request including a first policy section identifier (PSI) list corresponding to a UE policy stored in the user equipment. According to an embodiment, a registration request message may include a user equipment identifier (e.g., Subscription Permanent Identifier (SUR), SUCI (Subscription Concealed Identifier (SUCI), 5G Globally Unique Temporary Identifier (5G-GUTI), etc.), a request slice (Requested NSSAI: slice information that the user equipment wants to use by accessing the network), a UE policy container, UE policy-related information (e.g., a first PSI list indicating the UE policy stored in the user equipment) (a list of PSIs)), and the like. The UE policy container may include UE policy-related information stored in the user equipment (e.g., a first PSI list indicating a UE policy stored in the user equipment (a list of PSIs)). 
     In operation  1030 , the user equipment may receive a registration approval message including a second PSI list corresponding to the updated UE policy from an Access and Mobility Management Function (AMF). In an embodiment, the latest list of PSIs indicating the updated UE policy is referred to as the second PSI list. The AMF may transmit a DL Non Access Stratum (NAS) Transport message to the user equipment. The DL NAS Transport message may include UE policy information and the second PSI list received by the AMF from the PCF in operation  318 . 
     In operation  1050 , the user equipment may update the user equipment policy based on the received second PSI list. In an embodiment, the user equipment may store the received UE policy information, the second PSI list, or the like. In addition, the user equipment may apply the received UE policy information. The user equipment may determine when to apply the received UE policy. For example, the user equipment may determine to apply the UE policy immediately upon receipt. Alternatively, the user equipment may determine to apply the UE policy in an idle mode. Alternatively, the user equipment may determine to apply the UE policy after one or more protocol data unit (PDU) sessions that are currently in use are ended. However, the present disclosure is not limited to the above example. 
       FIG.  11    is a flowchart of an operating method of a policy control function (PCF), according to an embodiment of the present disclosure. 
     Referring to  FIG.  11   , in operation  1110 , a PCF may receive, from a user equipment, a first policy section identifier (PSI) list corresponding to the UE policy stored in the user equipment. In an embodiment, the user equipment may configure a registration request message including the first PSI list and transmit the same to the base station, the base station may transmit the registration request message to the AMF, and the AMF may store information received from the user equipment, for example, the first PSI list (a list of PSIs) indicating the UE policy stored in the user equipment, as a UE context, and the AMF may transmit the first PSI list to the PCF. 
     In operation  1130 , the PCF may identify whether the received first PSI list matches the second PSI list corresponding to the updated UE policy obtained from a Unified Data Repository (UDR). 
     In an embodiment, the PCF may compare the first PSI list among the information received from the AMF with the latest list of PSIs of the user equipment, stored in the PCF and/or UDR, that is, the second PSI list. When the first PSI list does not match the second PSI list, the PCF may determine that the user equipment is not storing the latest UE policy information, and determine to transmit the latest UE policy information to the user equipment. 
     In another embodiment, the PCF may determine to update the UE policy based on user equipment subscription information, operator policy, or the like. The PCF may determine the updated UE policy. Also, the PCF may allocate a latest PSI indicating the updated UE policy. The latest list of PSIS indicating the updated UE policy is referred to as the second PSI list. 
     In operation  1150 , the PCF may transmit, based on a result of the identifying, at least one of the first PSI list and the second PSI list to an Access and Mobility Management Function (AMF). The PCF may transmit a Npcf_UEPolicyControl_Create response message to the AMF. In an embodiment, the Npcf_UEPolicyControl_Create response message transmitted by the PCF to the AMF may include the latest UE policy information of the user equipment, that is, the second PSI list. The AMF may store second PSI information received from the PCF. For example, the AMF may store the second PSI information as a UE context. Accordingly, the AMF may store UE policy-related information of the user equipment, for example, the first PSI list and the second PSI list. 
     The methods according to the embodiments disclosed in the claims or the specification of the present disclosure may be implemented as hardware, software, or a combination of hardware and software. 
     When implemented in software, a computer-readable storage medium storing one or more programs (e.g., software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions directing the electronic device to execute the methods according to the embodiments of the present disclosure as described in the claims and the specification. 
     The programs (e.g., software modules or software) may be stored in random access memory (RAM), non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), a magnetic disc storage device, a compact disc-ROM (CD-ROM), a digital versatile disc (DVD), another optical storage device, or a magnetic cassette. Alternatively, the programs may be stored in memory including a combination of some or all of the above-mentioned storage media, A plurality of such memories may be included. 
     The programs may also be stored in an attachable storage device which is accessible through a communication network such as the Internet, an intranet, a local area network (LAN), a wireless LAN (WLAN), or a storage area network (SAN), or a combination thereof. Such a storage device may access the electronic device via an external port. Furthermore, an additional storage device on a communication network may access a device that performs the embodiments of the present disclosure. 
     In the embodiments of the present disclosure described above, an element or elements included in the present disclosure are expressed in a singular or plural form depending on the described embodiments of the present disclosure. However, the singular or plural form is appropriately selected for convenience of description and the present disclosure is not limited thereto. As such, an element expressed in a plural form may also be configured as a single element, and an element expressed in a singular form may also be configured as plural elements. 
     In the detailed description of the present disclosure, a specific embodiment has been described, but it goes without saying that various modifications are possible without departing from the scope of the present disclosure. Thus, the scope of the present disclosure is not limited to the embodiments described herein and should be defined by the appended claims and their equivalents. In other words, it is obvious to those skilled in the art that other modifications based on the technical spirit of the present disclosure can be implemented. Also, when necessary, the above respective embodiments may be employed in combination. For example, portions of the methods provided by the present disclosure may be combined with each other to enable the BS and the UE to operate. Also, although the above embodiments have been presented with reference to 5G and NR systems, other modifications based on the technical idea of the embodiments may also be implemented in connection with other systems such as LTE, LTE-A, and LTE-A-Pro systems.