Patent Publication Number: US-2023143200-A1

Title: Upf service-based packet delay status event exposure service method and device

Description:
TECHNICAL FIELD 
     The disclosure relates to a communication system, and more particularly, to a method and device for requesting a packet delay status using a UPF event exposure service. 
     BACKGROUND ART 
     In order to satisfy increases in demand for wireless data traffic now that a 4G communication system is commercially available, efforts are being made to develop an enhanced 5G communication system or a pre-5G communication system. Therefore, a 5G communication system or a pre-5G communication system is referred to as a beyond 4G network communication system or a post long term evolution (LTE) system. 
     In order to achieve a high data transmission rate, consideration is being given to implementing the 5G communication system in a mmWave band (e.g., 60 GHz band). In order to mitigate any route loss of electronic waves in a mmWave band and to increase transmission distances of electronic waves, the technologies of beamforming, massive multiple input and multiple output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna are being discussed for the 5G communication system. 
     Further, in order to enhance networks in the 5G communication system, the technologies of an innovative small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device to device communication (D2D), wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), and interference cancellation are being developed. 
     Further, hybrid frequency shift keying and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) methods; and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), which are advanced access technologies, are being developed for the 5G system. 
     The 5G system is considering support for various services compared to the existing 4G system. For example, the most representative services may include an enhanced mobile broad band (eMBB), ultra-reliable and low latency communication (URLLC), massive machine type communication (mMTC), evolved multimedia broadcast/multicast service (eMBMS), and the like. A system providing the URLLC service may be referred to as a URLLC system, and a system providing the eMBB service may be referred to as an eMBB system. Further, terms service and system may be used interchangeably. 
     The URLLC service is a service newly considered in the 5G system, unlike the existing 4G system and requires a service newly considered in the 5G system, and requires ultra-high reliability (e.g., about 10-5 packet error rate) and low latency (e.g., about 0.5 msec) requirements compared to other services. In order to satisfy these strict requirements, the URLLC service may need to apply a shorter transmission time interval (TTI) than the eMBB service, and various operating methods are being considered using this. 
     Innovation of Internet from a human-centered connection network in which a human generates and consumes information to an Internet of Things (IoT) network that gives and receives and processes information to and from distributed constituent elements such as things has occurred. Internet of everything (IoE) technology in which big data processing technology through connection to a cloud server is combined with IoT technology has been appeared. In order to implement the IoT, technology elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required; thus, nowadays, research is being carried out on technology of a sensor network, machine to machine (M2M), and machine type communication (MTC) for connection between things. 
     In an IoT environment, an intelligent Internet technology (IT) service that collects and analyzes data generated in connected things to provide a new value to human lives may be provided. 
     The IoT may be applied to the field of a smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliances, and high-tech medical service through fusion and complex connections between existing information technology (IT) and various industries. 
     Accordingly, various attempts for applying a 5G communication system to an IoT network are being made. For example, 5G communication technologies such as a sensor network, machine to machine (M2M), and machine type communication (MTC) have been implemented by the technique of beamforming, MIMO, and array antenna. Application of a cloud RAN as the foregoing big data processing technology may be an example of convergence of 5G technology and IoT technology. 
     As various services may be provided according to the above-mentioned description and the development of mobile communication systems, a method for efficiently using a non-public network (NPN) is particularly required. 
     DISCLOSURE 
     Technical Problem 
     The disclosure provides a method and device for effectively providing a service in a wireless communication system. 
     The technical problems to be achieved in the disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the disclosure belongs from the description below. 
     Solution to Problem 
     An embodiment of the disclosure proposes a method of providing packet delay status monitoring for an URLLC service based on an UPF event exposure service. 
     According to an embodiment of the disclosure, a method performed by a network exposure function (NEF) in a wireless communication system may include receiving, from an application function (AF), a first message requesting registration of an event subscription service to a user plane function (UPF); transmitting, to another network entity, a second message requesting information on the UPF; receiving, from the another network entity, a third message including the information on the UPF; and transmitting, to the UPF selected based on the information on the UPF, a fourth message requesting registration of the event subscription service. 
     Further, the second message may include at least one of a generic public subscription identifier (GPSI), an Internet protocol (IP) address of a terminal, a medium access control (MAC) address of the terminal, a data network name (DNN), slice information, or a subscription permanent identifier (SUPI). 
     Further, the another network entity may be a binding support function (BSF) or a policy control function (PCF). 
     Further, the method may further include receiving, from the UPF, a fifth message including information indicating occurrence of the subscribed event; and transmitting, to the AF, a sixth message including the information indicating occurrence of the event. 
     Further, at least one of a case that information indicating that information on the UPF is requested is included in the second message, information for identifying the UPF is included in the second message, or the second message is a preconfigured message requesting information on the UPF, the another network entity recognizes that the second message requests information on the UPF. 
     According to an embodiment of the disclosure, a method performed by an application function (AF) in a wireless communication system may include transmitting, to a binding support function (BSF), a first message requesting information on a user plane function (UPF); receiving, from the BSF, a second message including the information on the UPF; and transmitting, to the UPF selected based on the information on the UPF, a third message requesting registration of an event subscription service. 
     Further, the first message may include at least one of a generic public subscription identifier (GPSI), an Internet protocol (IP) address of a terminal, a medium access control (MAC) address of the terminal, a data network name (DNN), slice information, or a subscription permanent identifier (SUPI). 
     Further, the method may further include receiving, from the UPF, a fourth message including information indicating occurrence of the subscribed event. 
     According to an embodiment of the disclosure, a network exposure function (NEF) of a wireless communication system may include a transceiver; and a controller configured to control to receive, from an application function (AF) via the transceiver, a first message requesting registration of an event subscription service to a user plane function (UPF), transmit, to another network entity via the transceiver, a second message requesting information on the UPF, receive, from the another network entity via the transceiver, a third message including the information on the UPF, and transmit, to the UPF selected based on the information on the UPF via the transceiver, a fourth message requesting registration of the event subscription service. 
     According to an embodiment of the disclosure, an application function (AF) of a wireless communication system may include a transceiver; and a controller configured to control to transmit, to a binding support function (BSF) via the transceiver, a first message requesting information on a user plane function (UPF), receive, from the BSF via the transceiver, a second message including the information on the UPF, and transmit, to the UPF selected based on the information on the UPF via the transceiver, a third message requesting registration of an event subscription service. 
     Advantageous Effects of Invention 
     According to an embodiment of the disclosure, it is possible to provide a device and method for effectively providing a service in a wireless communication system. 
     The effects obtainable in the disclosure are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those of ordinary skill in the art to which the disclosure belongs from the description below. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    illustrates a structure of a 5G network according to an embodiment of the disclosure. 
         FIG.  2    illustrates a procedure for an external AF to use a packet delay status event exposure service according to an embodiment of the disclosure. 
         FIG.  3    illustrates a procedure for an internal AF to use a packet delay status event exposure service according to an embodiment of the disclosure. 
         FIG.  4    illustrates a procedure for an external AF to use a packet delay status event exposure service according to an embodiment of the disclosure. 
         FIG.  5    illustrates a procedure for storing a UPF ID in order for a PCF and a BSF to search for a UPF according to an embodiment of the disclosure. 
         FIG.  6    illustrates a procedure for updating a (PSA) UPF ID in a PCF and a BSF in the case that a PSA UPF is relocated according to an embodiment of the disclosure. 
         FIG.  7    is a block diagram illustrating a constitution of a terminal according to an embodiment of the disclosure. 
         FIG.  8    is a block diagram illustrating a constitution of a network entity according to an embodiment of the disclosure. 
     
    
    
     MODE FOR INVENTION 
     Hereinafter, preferred embodiments of the disclosure will be described in detail with reference to the accompanying drawings. In this case, it should be noted that in the accompanying drawings, the same components are denoted by the same reference numerals if possible. Further, detailed descriptions of well-known functions and configurations that may obscure the gist of the disclosure will be omitted. 
     In describing embodiments in this specification, descriptions of technical contents that are well known in the technical field to which the disclosure pertains and that are not directly related to the disclosure will be omitted. This is to more clearly convey the gist of the disclosure without obscuring the gist of the disclosure by omitting unnecessary description. For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings. Further, the size of each component does not fully reflect the actual size. In each drawing, the same reference numerals are given to the same or corresponding components. 
     Advantages and features of the disclosure, and a method of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the disclosure is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only embodiments of the disclosure enable the disclosure to be complete, and are provided to fully inform the scope of the disclosure to those of ordinary skill in the art to which the disclosure belongs, and the disclosure is only defined by the scope of the claims. Like reference numerals refer to like components throughout the specification. 
     In this case, it will be understood that each block of message flow diagrams and combinations of the message flow diagrams may be performed by computer program instructions. Because these computer program instructions may be mounted in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, the instructions performed by a processor of a computer or other programmable data processing equipment generate a means that performs functions described in the message flow diagram block(s). Because these computer program instructions may be stored in a computer usable or computer readable memory that may direct a computer or other programmable data processing equipment in order to implement a function in a particular manner, the instructions stored in the computer usable or computer readable memory may produce a production article containing instruction means for performing the function described in the message flow diagram block(s). 
     Because the computer program instructions may be mounted on a computer or other programmable data processing equipment, a series of operational steps are performed on the computer or other programmable data processing equipment to generate a computer-executed process; thus, instructions for performing a computer or other programmable data processing equipment may provide steps for performing functions described in the message flow diagram block(s). 
     Further, each block may represent a module, a segment, or a portion of a code including one or more executable instructions for executing a specified logical function(s). Further, it should be noted that in some alternative implementations, functions recited in the blocks may occur out of order. For example, two blocks illustrated one after another may in fact be performed substantially simultaneously, or the blocks may be sometimes performed in the reverse order according to the corresponding function. 
     In this case, the term ‘-unit’ used in this embodiment means software or hardware components such as FPGA or ASIC, and ‘-unit’ performs certain roles. However, ‘-unit’ is not limited to software or hardware. ‘-unit’ may be configured to reside in an addressable storage medium or may be configured to reproduce one or more processors. Therefore, as an example, ‘-unit’ includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuit, data, databases, data structures, tables, arrays, and variables. Functions provided in the components and ‘-units’ may be combined into a smaller number of components and ‘-units’ or may be further separated into additional components and ‘-units’. Further, components and ‘-units’ may be implemented to reproduce one or more CPUs in a device or secure multimedia card. 
     Hereinafter, the base station is a subject performing resource allocation of the terminal and may be at least one of a node B, base station (BS), eNode B (eNode B), gNB (gNode B), radio access unit, base station controller, or a node on the network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. Further, the embodiment of the disclosure may be applied to other communication systems having a similar technical background or channel type to the embodiment of the disclosure described below. Further, the embodiments of the disclosure may be applied to other communication systems through some modifications within a range that does not significantly depart from the scope of the disclosure as determined by a person having skilled technical knowledge. 
     A term for identifying an access node used in the following description, a term referring to a network entity or a network function (NF), a term referring to messages, a term referring to an interface between network objects, and terms referring to various identification information are exemplified for convenience of description. Accordingly, the disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used. 
     Hereinafter, for convenience of description, some terms and names defined in the 3rd generation partnership project long term evolution (3GPP) standard may be used. However, the disclosure is not limited by the above terms and names, and may be equally applied to systems conforming to other standards. 
     Embodiments of the disclosure provide a method in which an external/internal application function (AF)  160  in a 5G core (5GC) may use a packet delay status service provided to a user plane function (UPF) event exposure service using a service-based interface (SBI). 
       FIG.  1    illustrates a structure of a 5G network according to an embodiment of the disclosure. With reference to  FIG.  1   , descriptions of network entities or network nodes constituting a 5G network are as follows. 
     An (radio) access network ((R)AN)  115  is a subject that performs radio resource allocation of a terminal  110  and may be an at least one of an eNode B, a node B, a base station (BS), a next generation radio access network (NG-RAN), a 5G-AN, a radio access unit, a base station controller, or a node on a network. The terminal  110  may include a user equipment (UE), a next generation UE (NG UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. Hereinafter, although the embodiment of the disclosure is described by taking the 5G system as an example, the embodiment of the disclosure may be applied to other communication systems having a similar technical background. Further, the embodiments of the disclosure may be applied to other communication systems through some modifications within a range that does not significantly depart from the scope of the disclosure as determined by a person having skilled technical knowledge. 
     The wireless communication system defines a next generation (gen) core (NG core) or a 5G core network (5GC), which is a new core network as it evolves from a 4G system to a 5G system. The new core network virtualized all the existing network entities (NEs) and made it into a network function (NF). According to an embodiment of the disclosure, a network function may mean a network entity, a network component, and a network resource. 
     According to an embodiment of the disclosure, a 5GC may include NFs illustrated in  FIG.  1   . The 5GC is not limited to an example of  FIG.  1    and may include a larger number of NFs or a smaller number of NFs than that illustrated in  FIG.  1   . 
     According to an embodiment of the disclosure, an access and mobility management function (AMF)  120  may be a network function for managing the mobility of the terminal  110 . 
     According to an embodiment of the disclosure, a session management function (SMF)  130  may be a network function for managing a packet data network (PDN) connection provided to the terminal  110 . The PDN connection may be referred to as a protocol data unit (PDU) session. 
     According to an embodiment of the disclosure, a policy control function (PCF)  150  may be a network function that applies a service policy of a mobile communication operator to a terminal, a charging policy, and a policy for a PDU session. 
     According to an embodiment of the disclosure, unified data management (UDM)  155  may be a network function for storing information on a subscriber. 
     According to an embodiment of the disclosure, a network exposure function (NEF)  140  may be a function of providing information on the terminal to a server outside the 5G network. Further, the NEF  140  may provide a function of providing information necessary for providing a service to the 5G network and storing the information in a user data repository (UDR) (not illustrated). 
     According to an embodiment of the disclosure, a user plane function (UPF)  125  may be a function that serves as a gateway for transferring user data (PDU) to a data network (DN)  175 . 
     In particular, in the disclosure, Nupf, which is an SBI interface, is defined to the UPF  125 , thereby providing an event exposure service to other NFs. 
     According to an embodiment of the disclosure, a network repository function (NRF)  145  may perform a function of discovering the NF. 
     According to an embodiment of the disclosure, an authentication server function (AUSF)  165  may perform terminal authentication in a 3GPP access network and a non-3GPP access network. 
     According to an embodiment of the disclosure, a network slice selection function (NSSF)  135  may perform a function of selecting a network slice instance provided to the terminal  140 . 
     According to an embodiment of the disclosure, a service communication proxy (SCP)  170  may provide an indirect communication method that substitutes for service search, call, response, and the like in interworking between NFs. 
     According to an embodiment of the disclosure, the DN  175  may be a data network in which the terminal  110  transmits and receives data in order to use a service of a network provider or a 3rd party service. 
       FIG.  2    illustrates a procedure for an external AF to use a packet delay status event exposure service according to an embodiment of the disclosure. 
     With reference to  FIG.  2   , in step  210 , in order to subscribe or cancel a subscription to a packet delay status event exposure service, an AF  201  may transmit a service subscription request or cancellation message (Nnef_EventExposure_Subscribe/Unsubscribe request) to an NEF  203 . 
     In order to cancel a subscription, a subscription correlation ID that identifies the existing event service subscription should be sent together. The subscription request message may include at least one of the following parameters.
         Event ID(s)
           Packet Delay Status (PDS)   
           Target of Event Reporting
           It may be any combination of a generic public subscription identifier (GPSI), external group identifier, UE IP address (IPv4 address or IPv6 prefix), UE medium access control (MAC) address, AF-Service-Identifier, or data network name (DNN)/S-NSSAI (network slice selection assistance information) combination information.   QoS Flow Detection Information (Traffic Descriptor Information)   Source address: UE IP address(IPv4 address or IPv6 prefix), UE MAC address   Destination address: Server IP address(IPv4 address or IPv6 prefix), UE MAC address   Source(UE) port number   Destination(Server) port number   Protocol ID (IPv4) or Next Header type (IPv6)   Flow Label(IPv6)   Ethertype(Ethernet)   
           Event Reporting Information
           Event reporting mode   Periodic, one time, on event detection   Immediate reporting flag   Minimum waiting time if reporting frequency: event detection   
           Notification Target Address(+Notification Correlation ID)
           AF ID(address), NEF ID(address)   Event Filter Information   Reporting frequency: event detection   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (threshold of the DL packet delay)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (threshold of the UL packet delay)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (threshold of the round trip packet delay)   Reporting frequency: periodic   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (reporting time period)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (reporting time period)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (reporting time period)   Reporting frequency: one time   Event Parameter Type1 (Event Parameter Value1)   
           DL packet delay (PDU Session is released)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (PDU Session is released)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (PDU Session is released)   Expiry time   The time up to which the subscription is desired to be kept as active       

     In step  220 , in order to find a UPF through which a specific service data flow (SDF) or packet flow passes, the NEF  203  may transmit an Nbsf_Management_Discovery request message to a binding support function (BSF)  205 . The operation provides a search for a PCF or an UPF in charge of a specific PDU session. An input value may be a combination of an UE IP address (IPv4 address or IPv6 prefix), an UE MAC address, DNN, DN information (e.g., S-NSSAI), subscription permanent identifier (SUPI), GPSI, and the like. In step  210 , when the NEF  203  receives an AF-service-identifier as a target of event reporting value, the NEF  203  may change the AF-service-identifier to a DNN/S-NSSAI combination. Further, in order to designate a discovering NF to be searched, (PCF or UPF) may be designated as an input value of the function. Alternatively, in the case that the Nbsf_Management_Discovery request message includes information that may use for identifying the UPF, the Nbsf_Management_Discovery request message is a message requesting information on the UPF (e.g., UPF ID), and the BSF that has received this may recognize it. Another method is to differentiate the discovering NF to change a name of a service operation. That is, when searching for the UPF, the Nbsf_management_Discovery_UPF request (GPSI, UE IP address) service operation is used, and when searching for a PCF, an Nbsf_management_Discovery_PCF request (GPSI, UE IP address) is used. Another method is to differentiate the search target NF using a “TYPE” parameter. For example, there may be a method in which TYPE1 is defined as a PCF, TYPE2 is defined as a UPF, and TYPE3 is defined when both a PCF and a UPF are searched at the same time. For example, when searching for a UFP, it is used as in an Nbsf_management_Discovery_Request (GPSI, UE IP address, TYPE2). When the NEF  203  receives an external group identifier as an input value in step  210 , the NEF  203  may search for all UPFs in charge of all UEs belonging to the group and send a service subscription request. 
     In step  230 , the BSF  205  may transmit identification information (e.g., ID of a UPF  207 ) of the UPF  207  requested to search using the GPSI and the UE IP address to the NEF  203  through the Nbsf_management_Discovery response message. In order to search for the UPF  207 , the NEF  203  may use any combination of a UE IP address (IPv4 address or IPv6 prefix), UE MAC address, AF-service-identifier, DNN, DN information (e.g., S-NSSAI), SUPI, or GPSI values. 
     In step  240 , in order to subscribe or cancel a subscription to the packet delay status event exposure service, the NEF  203  may transmit a service subscription request or cancellation message (Nupf_EventExposure_Subscribe/Unsubscribe request) to the UPF  207 . In order for the NEF  203  to cancel a subscription, the NEF  203  may send together a subscription correlation ID identifying an existing event service subscription to the UPF  207 . When the NEF  203  receives an AF-service-identifier as the target of event reporting value in step  210 , the NEF  203  may change the AF-service-identifier to a DNN/S-NSSAI combination. The NEF  203  may add an address thereof to the notification target address and information received from the AF  201  in step  210  and transmit it to the UPF  207 . This is for the NEF  203  to receive a notification on a change when a change of information subscribed to the UPF  207  occurs. When the service subscription is authorized by the UPF  207 , the UPF  207  may store the event trigger and the identity of the requester. 
     The UPF  207  may perform a packet delay status event exposure service for a specific QoS flow of a specific UE through target of event reporting information. The specific QoS flow may be specified through traffic detection information in target of event reporting information. The UPF  207  may report to an event exposure service subscriber at an event detection/periodic/one time period according to the reporting frequency in event filter information. The UPF  207  may report the DL packet delay/UL packet delay/round trip packet delay value to the subscriber every corresponding period. The event detection period may be notified to the subscriber when the packet delay is a threshold or more. The periodic period may be reported to the subscriber at every reporting time period interval. One time period may be reported to the subscriber when a PDU session in which the corresponding QoS flow flows is released. Event reporting information may include an event reporting mode and include an immediate reporting flag indicating whether to immediately send reporting to the subscriber. A minimum waiting time if reporting frequency indicates a time value to wait until at least the next report after detecting an event and reporting it to the subscriber in the event detection period. This is to prevent frequent reports due to events occurring too frequently. 
     The UPF  207  may measure the DL, UL and round trip packet delay of an N3 interface with the NG-RAN in order to measure the packet delay for a specific QoS flow, and the packet delay between the UE and the NG-RAN may be measured by requesting to the NG-RAN. 
     In step  250 , the UPF  207  may transmit a Nupf_EventExposure_Subscribe/Unsubscribe response message to the NEF  203  in response to a subscription or cancellation of a subscription to the service. The message may include a subscription correlation ID and an expiry time. 
     In step  260 , the NEF  203  may transmit a Nnef_EventExposure_Subscribe/Unsubscribe response message to the AF  201  in response to a subscription or cancellation of a subscription to the service. The message may include a subscription correlation ID and an expiry time. 
     In step  270 , the UPF  207  may detect occurrence of an event and transmit the event report together with a time stamp to the NEF  203  through a Nupf_EventExposure_Notify message. 
     The NEF  203  may store event report information together with the time stamp in a UDR (not illustrated) using a Nudr_DM_Create or Nudr_DM_Update message. 
     In step  280 , the NEF  203  may transmit the received event report to the AF  201  through Nnef_EventExposure_Notify. 
       FIG.  3    illustrates a procedure for an internal AF to use a packet delay status event exposure service according to an embodiment of the disclosure. 
     The embodiment illustrated in  FIG.  3    is similar to the procedure of the embodiment illustrated in  FIG.  2   , except that the NEF  203  is not used for subscribing to a packet delay status event exposure service because an AF  301  is in a network. 
     With reference to  FIG.  3   , in step  310 , in order to find a UPF through which a specific SDF or packet flow passes, the AF  301  may transmit an Nbsf_Management_Discovery request message to a binding support function (BSF)  303 . The operation provides a search for a PCF or a UPF in charge of a specific PDU session. An input value may be a combination of an UE IP address (IPv4 address or IPv6 prefix), an UE MAC address, a DNN, DN information (e.g., S-NSSAI), SUPI, GPSI, and the like. Further, in order to designate a discovering NF to be searched, (PCF or UPF) may be designated as an input value of the function. Another method may be to differentiate the discovering NF to change the name of the service operation. That is, there may be a method of using an Nbsf_management_Discovery_UPF request (GPSI, UE IP address) service operation when searching for the UPF and using an Nbsf_management_Discovery_PCF request (GPSI, UE IP address) when searching for the PCF. As another method, there may be a method of differentiating a search target NF using a “TYPE” parameter. For example, TYPE1 may be defined as the PCF, TYPE2 may be defined as the UPF, and TYPE3 may be defined when both the PCF and the UPF are searched at the same time. For example, when searching for the UFP, it may be used as in Nbsf_management__Discovery_Request (GPSI, UE IP address, TYPE2). 
     In step  320 , the BSF  303  may transmit the identification information (e.g., ID of a UPF  305 ) of the UPF  305  requested to search using the GPSI and the UE IP address to the AF  301  through the Nbsf_management_Discovery response message. In order to search for the UPF  305 , the AF  301  may use any combination of a UE IP address (IPv4 address or IPv6 prefix), UE MAC address, AF-Service-Identifier, DNN, DN information (e.g., S-NSSAI), SUPI, or GPSI values. 
     In step  340 , in order to subscribe or unsubscribe to the packet delay status event exposure service, the AF  301  may transmit a service subscription request or cancellation message (Nupf_EventExposure_Subscribe/Unsubscribe request) to the UPF  305 . In order to cancel a subscription, the AF  301  may send a subscription correlation ID that identifies an existing event service subscription together with the service subscription cancellation message to the UPF  305 . When the service subscription is authorized by the UPF  305 , the UPF  305  may store the event trigger and the identity of the requester. The subscription request message may include at least one of the following parameters.
         Event ID(s)   Packet Delay Status (PDS)   Target of Event Reporting   It may be any combination of a generic public subscription identifier (GPSI), external group identifier, UE IP address (IPv4 address or IPv6 prefix), UE MAC address, AF-Service-Identifier, or DNN/S-NSSAI combination information.       

     QoS Flow Detection Information (traffic Descriptor Information)
         Source address: UE IP address(IPv4 address or IPv6 prefix), UE MAC address   Destination address Server IP address(IPv4 address or IPv6 prefix), UE MAC address   Source(UE) port number   Destination(Server) port number   Protocol ID (IPv4) or Next Header type (IPv6)   Flow Label(IPv6)   Ethertype(Ethernet)   Event Reporting Information   Event reporting mode   Periodic, one time, on event detection   Immediate reporting flag   Minimum waiting time if reporting frequency: event detection   Notification Target Address(+Notification Correlation ID)   AF ID(address), NEF ID(address)   Event Filter Information   Reporting frequency: event detection   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (threshold of the DL packet delay)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (threshold of the UL packet delay)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (threshold of the round trip packet delay)   Reporting frequency: periodic   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (reporting time period)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (reporting time period)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (reporting time period)   Reporting frequency one time   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (PDU Session is released)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (PDU Session is released)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (PDU Session is released)   Expiry time   The time up to which the subscription is desired to be kept as active       

     The UPF  305  may perform a packet delay status event exposure service for a specific QoS flow of a specific UE through target of event reporting information. The specific QoS flow may be specified through traffic detection information in target of event reporting information. The UPF  305  may report to the event exposure service subscriber at an event detection/periodic/one time period according to the reporting frequency in the event filter information. The UPF  305  may report the DL packet delay/UL packet delay/round trip packet delay value to the subscriber every corresponding period. The event detection period may be notified to the subscriber when the packet delay is a threshold or more. The periodic period may be reported to the subscriber at every reporting time period interval. One time period may be reported to the subscriber when a PDU session in which the corresponding QoS flow flows is released. Event reporting information may include an event reporting mode and include an immediate reporting flag indicating whether to immediately send reporting to the subscriber. A minimum waiting time if reporting frequency indicates a time value to wait until at least the next report after detecting an event and reporting it to the subscriber in the event detection period. This is to prevent frequent reports due to events occurring too frequently. 
     The UPF  305  may measure DL, UL, and round trip packet delay of an N3 Interface with the NG-RAN in order to measure packet delay for a specific QoS flow, and packet delay between the UE and the NG-RAN may be measured by requesting to the NG-RAN. 
     In step  340 , the UPF  305  may transmit a Nupf_EventExposure_Subscribe/Unsubscribe response message to the AF  301  in response to a subscription or cancellation of a subscription to a service. 
     The message may include a subscription correlation ID and an expiry time. 
     In step  350 , the UPF  305  may detect occurrence of an event and transmit the event report together with a time stamp to the AF  301  through a Nupf_EventExposure_Notify message. 
       FIG.  4    illustrates a procedure for an external AF to use a packet delay status event exposure service according to an embodiment of the disclosure. 
     All procedures of the embodiment illustrated in  FIG.  4    are basically the same as those in  FIG.  2   , but are different from those in  FIG.  2    in that the PCF instead of the BSF is used for searching for the UPF. That is, the embodiment of  FIG.  4    is similar to the embodiment illustrated in  FIG.  2    except for steps  420  and  430 . 
     With reference to  FIG.  4   , in step  410 , in order to subscribe or cancel a subscription to a packet delay status event exposure service, an AF  401  may transmit a service subscription request or cancellation message (Nnef_EventExposure_Subscribe/Unsubscribe request) to an NEF  403 . In order to cancel a subscription, a subscription correlation ID that identifies the existing event service subscription should be sent together. The subscription request message may include at least one of the following parameters.
         Event ID(s)   Packet Delay Status (PDS)   Target of Event Reporting   It may be any combination of a generic public subscription identifier (GPSI), external group identifier, UE IP address (IPv4 address or IPv6 prefix), UE MAC address, AF-Service-Identifier, and DNN/S-NSSAI combination information.   QoS Flow Detection Information (Traffic Descriptor Information)   Source address: UE IP address(IPv4 address or IPv6 prefix), UE MAC address   Destination address Server IP address(IPv4 address or IPv6 prefix), UE MAC address   Source(UE) port number   Destination(Server) port number   Protocol ID (IPv4) or Next Header type (IPv6)   Flow Label(IPv6)   Ethertype(Ethernet)   Event Reporting Information   Event reporting mode   Periodic, one time, on event detection   Immediate reporting flag   Minimum waiting time if reporting frequency: event detection   Notification Target Address(Notification Correlation ID)   AF ID(address), NEF ID(address)   Event Filter Information   Reporting frequency: event detection   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (threshold of the DL packet delay)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (threshold of the UL packet delay)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (threshold of the round trip packet delay)   Reporting frequency: periodic   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (reporting time period)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (reporting time period)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (reporting time period)   Reporting frequency: one time   Event Parameter Type1 (Event Parameter Value1)   DL packet delay (PDU Session is released)   Event Parameter Type2 (Event Parameter Value2)   UL packet delay (PDU Session is released)   Event Parameter Type1 (Event Parameter Value1)   Round trip packet delay (PDU Session is released)   Expiry time   The time up to which the subscription is desired to be kept as active       

     In step  420 , in order to find a UPF through which a specific SDF or packet flow passes, the NEF  403  may transmit an Npcf_Management_Discovery request message to a policy control function (PCF)  405 . The operation provides a search for a UPF  407  in charge of a specific PDU session. An input value may be a combination of an UE IP address (IPv4 address or IPv6 prefix), an UE MAC address, a DNN, DN information (e.g., S-NSSAI), SUPI, GPSI, and the like. In step  410 , when the NEF  403  receives an AF-Service-Identifier as a target of event reporting value, the NEF  403  may change the AF-Service-Identifier to a DNN/S-NSSAI combination. When the NEF  403  receives the external group identifier as an input value in step  410 , the NEF  403  may search for all UPFs in charge of all UEs belonging to a group and send a service subscription request. 
     In step  430 , the PCF  405  may transmit the identification information (e.g., the ID of the UPF  407 ) of the UPF  407  requested to search using the GPSI and the UE IP address to the NEF  403  through the Npcf_management_Discovery response message. In order to search for the UPF  407 , the NEF  403  may use any combination of an UE IP address (IPv4 address or IPv6 prefix), an UE MAC address, an AF-Service-Identifier, a DNN, DN information (e.g., S-NSSAI), SUPI, or GPSI values. 
     In step  440 , in order to subscribe or cancel a subscription to the packet delay status event exposure service, the NEF  403  may transmit a service subscription request or cancellation message (Nupf_EventExposure_Subscribe/Unsubscribe request) to the UPF  407 . In order for the NEF  403  to cancel a subscription, the NEF  403  may transmit together a subscription correlation ID identifying an existing event service subscription to the UPF  407 . When the NEF  403  receives an AF-Service-Identifier as a target of event reporting value in step  410 , the NEF  403  may change the AF-Service-Identifier to a DNN/S-NSSAI combination. The NEF  403  may add an address thereof to the information received from the AF  401  and notification target address in step  410  and transmit it to the UPF  407 . This is for the NEF  403  to receive a notification of a change when a change occurs in information subscribed to the UPF  407 . When the service subscription is authorized by the UPF  407 , the UPF  407  may store the event trigger and the identity of the requester. 
     The UPF  407  may perform a packet delay status event exposure service for a specific QoS flow of a specific UE through target of event reporting information. The specific QoS flow may be specified through traffic detection information in target of event reporting information. The UPF  407  may report to the event exposure service subscriber at an event detection/periodic/one time period according to the reporting frequency in the event filter information. The UPF  407  may report a DL packet delay/UL packet delay/round trip packet delay value to the subscriber every corresponding period. The event detection period may be notified to the subscriber when the packet delay is a threshold or more. The periodic period may be reported to the subscriber at every reporting time period interval One time period may be reported to the subscriber when a PDU session in which the corresponding QoS flow flows is released. Event reporting information may include an event reporting mode and include an immediate reporting flag indicating whether to immediately send reporting to the subscriber. A minimum waiting time if reporting frequency indicates a time value to wait until at least the next report after detecting an event and reporting it to the subscriber in an event detection period. This is to prevent frequent reports due to events occurring too frequently. 
     The UPF  407  may measure the DL, UL, and round trip packet delay of an N3 interface with the NG-RAN in order to measure the packet delay for a specific QoS flow, and the packet delay between the UE and the NG-RAN may be measured by requesting to the NG-RAN. 
     In step  450 , the UPF  407  may transmit a Nupf_EventExposure_Subscribe/Unsubscribe response message to the NEF  403  in response to a subscription or cancellation of a subscription to a service. The message may include a subscription correlation ID and an expiry time. 
     In step  460 , the NEF  403  may transmit an Nnef_EventExposure_Subscribe/Unsubscribe response message to the AF  401  in response to a subscription or cancellation of a subscription to a service. The message may include a subscription correlation ID and an expiry time. 
     In step  470 , the UPF  407  may detect occurrence of an event to transmit the event report together with a time stamp to the NEF  403  through a Nupf_EventExposure_Notify message. The NEF  403  may store event report information together with a time stamp in a UDR (not illustrated) using a Nudr_DM_Create or Nudr_DM_Update message. 
     In step  480 , the NEF  403  may transmit the received event report to the AF  401  through Nnef_EventExposure_Notify. 
       FIG.  5    illustrates a procedure for storing a UPF ID in order for a PCF and a BSF to search for a UPF according to an embodiment of the disclosure. 
     The procedure of the embodiment illustrated in  FIG.  5    may be performed by an SMF initiated SM policy association modification procedure performed during a PDU session establishment procedure. 
     With reference to  FIG.  5   , in step  510 , a PDU session establishment procedure may be performed between an SMF  501 , a PCF  503 , and a BSF  505 . 
     In step  520 , in order to update the SM policy association of the generated PDU session, the SMF  501  transmits an Npcf_SMPolicyControl_Update request message to the PCF  503 . Parameters included in the message may include at least one of an SM policy association ID, IPv4 address and/or IPv6 network prefix, user location information, UE time zone, serving network, RAT type, session AMBR, or subscribed default QoS information, DN authorization profile index, MAC address, port number of manageable Ethernet port, UE-DS-TT residence time and port management information container, MA PDU request indication, or MA PDU network-upgrade allowed indication. In particular, the SMF  501  may add a (PSA) UPF ID and a (PSA) UPF address in charge of the corresponding PDU session to the message and transmit the message to the PCF  503 . Thereby, the PCF  503  may store the UPF ID and UPF address in charge of the generated PDU session. 
     In step  530 , the PCF  503  may transmit an Npcf_SMPolicyControl_Update response message to the SMF  501  in response to the Npcf_SMPolicyControl_Update request message. 
     In step  540 , the PCF  503  may register PDU session related information to the BSF  505  through the Nbsf_Management_Register request message. The registration information may include at least one of an UE address(es), SUPI, GPSI, DNN, DN information (e.g, S-NSSAI), PCF address(es), PCF id, or PCF set ID. In order to register UPF information in the BSF  505 , the PCF  503  may additionally provide the UPF address (es) and the UPF id to the BSF  505 . Thereby, the BSF  505  may store the UPF ID and UPF address in charge of the generated PDU session. 
     In step  550 , the BSF  503  may transmit an Nbsf_Management_Register response message to the PCF  503  in response to the Nbsf_Management_Register request message. 
       FIG.  6    illustrates a procedure for updating a (PSA) UPF ID in a PCF and a BSF in the case that a PSA UPF is relocated according to an embodiment of the disclosure With reference to  FIG.  6   , in step  610 , the PSA UPF may be relocated. 
     In step  620 , after the PSA UPF is relocated, in order to update the SM policy association of a PDU session, an SMF  601  may transmit an Npcf_SMPolicyControl_Update request message to a PCF  603 . Parameters included in the message may include at least one of an SM policy association ID, IPv4 address and/or IPv6 network prefix, user location information, UE time zone, serving network, RAT type, session AMBR, or subscribed default QoS information, DN authorization profile index, MAC address, port number of manageable Ethernet port, UE-DS-TT residence time and port management information container, MA PDU request indication, or MA PDU network-upgrade allowed indication. In particular, the SMF  601  may add the (PSA) UPF ID and (PSA) UPF address changed by PSA UPF relocation to the message to transmit the message to the PCF  603 . Thereby, the PCF  603  may store the UPF ID and UPF address changed by the PSA UPF relocation. 
     In step  630 , the PCF  603  may transmit an Npcf_SMPolicyControl_Update response message to the SMF  601  in response to the Npcf_SMPolicyControl_Update request message. 
     In step  640 , the PCF  603  may update the PDU session related information to a BSF  605  through the Nbsf_Management_Update request message. Parameters included in the message may include at least one of a binding identifier for a PDU session, a UE address(es), or a PCF id. In order to update the UPF information to the BSF  605 , the PCF  603  may additionally provide an UPF address (es) and an UPF id to the BSF  605 . Thereby, the BSF  605  may store the UPF ID and UPF address changed by PSA UPF relocation. 
     In step  550 , the BSF  605  may transmit an Nbsf_Management_Register response message to the PCF  603  in response to the Nbsf_Management_Update request message. 
     Hereinafter, the event exposure service parameters that should be added to support the packet delay status event exposure service will be described. 
     [Table 1] Enumeration UpfEvent 
       
                             TABLE 1                       Appli-       Enumeration value   Description   cability                  PDS   Packet Delay Status   PacketDelayStatus                    
[Table 1] adds a PDS, which is a new event ID to a UPF event table for the packet delay status event. [Table 2] Definition of type NupfEventExposure
 
                                         TABLE 2               Attribute                           name   Data type   P   Cardinality   Description   Applicability                  Supi   Supi   C   0 . . . 1   Subscription Permanent                           Identifier (NOTE)       Gpsi   Gpsi   C   0 . . . 1   Generic Public Subscription                       Identifier (NOTE)       anyUeInd   boolean   C   0 . . . 1   This IE shall be present if the                       event subscription is                       applicable to any UE.                       Default value “FALSE” is                       used, if not present (NOTE)       groupId   GroupId   C   0 . . . 1   Identifies a group of UEs.                       (NOTE)       pduSeId   PduSessionId   C   0 . . . 1   PDU session ID (NOTE)       maxWaitTime   DateTime   C   0.1   Maximum wait time after   PacketDelayStatus                       reporting                    
[Table 2] adds a maxWaitTime, which is a new type for the packet delay status event to a type definition table. [Table 3] Type EventSubscription
 
                                         TABLE 3               Attribute name   Data type   P   Cardinality   Description   Applicability                  event   SmfEvent   M   1   Subscribed events           dnaiChType   DnaiChangeType   C   0 . . . 1   For event UP path change,                       this attribute indicates                       whether the subscription is                       for early, late, or early and                       late DNAI change                       notification shall be                       supplied.       dddTraDes   DddTrafficDescriptor   C   0 . . . 1   The traffic descriptor of the   DownlinkDataDeliveryStatus                       downlink data source. May                       be included for event                       “downlink data delivery                       status”.       dddStati   array(DddStatus)   C   1 . . . N   May be included for event   DownlinkDataDeliveryStatus                       “downlink data delivery                       status”. The subscribed stati                       (discarded, transmitted,                       buffered) for the event. If                       omitted all stati are                       subscribed.       pdsTraDes   PdsTrafficDescirptor   C       The traffic descriptor of the   PacketDelayStatus                       target QoS Flow.       pdsNotEve   PdsTrafficDescirptor   C       For which Event Item is   PacketDelayStatus                       needed for detection.       pdsNotThr   Notification_threshold   C       Frequency for Event   PacketDelayStatus                       detection                    
[Table 3] adds PdsTrafticDescirptor, PdsTrafticDescirptor, and Notification_threshold types, which are new EventSubscription types for a packet delay status event. [Table 4] Enumeration Notification Method-PDS
 
     
       
         
           
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                 Appli- 
               
               
                 Enumeration value 
                 Description 
                 cability 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 PERIODIC 
                 The notification is 
               
               
                   
                 periodically sent. 
               
               
                 PDU_SESSION_RELEASE 
                 The notification is 
               
               
                   
                 only sent when 
               
               
                   
                 PDU Session is released 
               
               
                 ON_EVENT_DETECTION 
                 The notification is 
               
               
                   
                 sent each time 
               
               
                   
                 the event is detected. 
               
               
                   
               
            
           
         
       
     
     [Table 5] Enumeration NotificationEventItem 
       
     
       
         
           
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                   
                 Appli- 
               
               
                 Enumeration value 
                 Description 
                 cability 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 DL_PACKET_DELAY 
                 Downlink packet delay 
               
               
                   
                 between UE and PSA UPF 
               
               
                 UP_PACKET_DELAY 
                 Uplink packet delay 
               
               
                   
                 between UE and PSA UPF 
               
               
                 ROUND_TRIP_DELAY 
                 Round trip packet delay 
               
               
                   
                 between UE and PSA UPF 
               
               
                   
               
            
           
         
       
     
     [Table 6] Enumeration Notification_threshold 
       
                             TABLE 6                       Appli-       Enumeration value   Description   cability                                        DL_PACKET_DELAY_threshold   Threshold for           Downlink packet delay       UP_PACKET_DELAY_threshold   Threshold for           Uplink packet delay       ROUND_TRIP_DELAY_threshold   Threshold Round           trip packet delay                    
[Table 4], [Table 5], and [Table 6] define a new enumeration type for event filter information (frequency and event items) of a packet delay status event. [Table 7] Definition of type PdsTrafficDescriptor
 
                                         TABLE 7               Attribute name   Data type   P   Cardinality   Description   Applicability                  ipv4Addr   Ipv4Addr   C   0 . . . 1   Ipv4 address of the source (UE IP   PacketDelayStatus                       address)       ipv6Addr   Ipv6Addr   C   0 . . . 1   Ipv6 address of the source (UE IP   PacketDelayStatus                       address)       port   Uinteger   O   0 . . . 1   Port number of the of the source   PacketDelayStatus                       (UE)       ipv4Addr   Ipv4Addr   C   0 . . . 1   Ipv4 address of the destination   PacketDelayStatus                       (Server)       ipv6Addr   Ipv6Addr   C   0 . . . 1   Ipv6 address of the destination   PacketDelayStatus                       (Server)       port   Uinteger   O   0 . . . 1   Port number of the of destination   PacketDelayStatus                       (Server)       Protocol ID                   PacketDelayStatus               NOTE:       At least one of the “ipv4Addr” attribute or the “ipv6Addr” attribute shall be included.            
[Table 7] defines a PdsTrafficDescriptor type for the packet delay status event. Through the information, the UPF may search for specific QoS flow. [Table 8] Nupf_EventExposure specific Data Types
 
                                 TABLE 8                   Section               Data type   defined   Description   Applicability                  PdsTrafficDescirptor   x.x.x.x   Traffic descriptor   PacketDelayStatus               of the target QoS               Flow       NotificationEventItem   x.x.x.x   Notification   PacketDelayStatus               Event Item       Notification_threshold   x.x.x.x   Threshold value   PacketDelayStatus               for frequency               (event detection)                    
[Table 8] defines newly defined data types for a packet delay status event. [Table 9] Definition of type EventNotification
 
                                         TABLE 9               Attribute name   Data type   P   Cardinality   Description   Applicability                  event   SmfEvent   M   1   Event that is notified.           timeStamp   DateTime   M   1   Time at which the event is                       observed.       supi   Supi   C   0 . . . 1   Subscription Permanent Identifier.                       It is included when the                       subscription applies to a group of                       UE(s) or any UE.       gpsi   Gpsi   C   0 . . . 1   Identifies a GPSI. It shall contain                       an MSISDN. It is included when                       it is available and the subscription                       applies to a group of UE(s) or any                       UE.       sourceDnai   Dnai   C   0 . . . 1   Source DN Access Identifier.                       Shall be included for event                       “UP_PATH_CH” if the DNAI                       changed (NOTE 1, NOTE 2).       targetDnai   Dnai   C   0 . . . 1   Target DN Access Identifier. Shall                       be included for event                       “UP_PATH_CH” if the DNAI                       changed (NOTE 1, NOTE 2).       dnaiChgType   DnaiChangeType   C   0 . . . 1   DNAI Change Type. Shall be                       included for event                       “UP_PATH_CH”.       sourceUeIpv4Addr   Ipv4Addr   O   0 . . . 1   The IPv4 Address of the served                       UE for the source DNAI. May be                       included for event                       “UP_PATH_CH”.       dlPacketDelay   DateTime   C   0 . . . 1   Downlink Packet Delay time   PacketDelayStatus                       between UE and PSA UPF. Shall                       be included for event “PDS” if                       DLPacketDelay is requested       ulPacketDelay   DateTime   C   0 . . . 1   Uplink Packet Delay time   PacketDelayStatus                       between UE and PSA UPF. Shall                       be included for event “PDS” if                       ULPacketDelay is requested.       roundtripPacketDelay   DateTime   C   0 . . . 1   RoundTrip Packet Delay time   PacketDelayStatus                       between UE and PSA UPF. Shall                       be included for event “PDS” if                       RoundTirpPacketDelay is                       requested.                    
[Table 9] defines newly defined EventNotification types for a packet delay status event.  FIG.  7    is a block diagram illustrating a constitution of a terminal according to an embodiment of the disclosure.
 
     With reference to  FIG.  8   , the terminal according to an embodiment of the disclosure may include a transceiver  710  and a controller  710  for controlling overall operations thereof. The transceiver  710  may include a transmitter and a receiver. The terminal may include a storage  730 . 
     The transceiver  710  may transmit and receive signals to and from other network entities. 
     The storage  730  may store various types of information such as information for an operation of the terminal and information received from other network entities. 
     The controller  720  may control the terminal to perform any one operation of the above-described embodiments. The controller  720  and the transceiver  710  do not necessarily have to be implemented into separate modules, and may be implemented into a single component in the form of a single chip. The controller  720  and the transceiver  710  may be electrically connected. For example, the controller  720  may be a circuit, an application-specific circuit, or at least one processor. Further, operations of the terminal may be realized by providing the memory device  730  storing the corresponding program code in an arbitrary component in the terminal. 
       FIG.  8    is a block diagram illustrating a constitution of a network entity according to an embodiment of the disclosure. 
     The network entity of the disclosure is a concept including a network function according to a system implementation. 
     With reference to  FIG.  8   , a network entity according to an embodiment of the disclosure may include a transceiver  810  and a controller  820  for controlling overall operations of the network entity. The transceiver  810  may include a transmitter and a receiver. The network entity may include a storage  830 . 
     The transceiver  810  may transmit and receive signals to and from other network entities. 
     The storage  830  may store various types of information such as information for an operation of the network entity and information received from other network entities. 
     The controller  820  may control the network entity to perform any one operation of the above-described embodiments. The controller  820  and the transceiver  810  do not necessarily have to be implemented into separate modules, and may be implemented into a single component in the form of a single chip. The controller  820  and the transceiver  810  may be electrically connected. For example, the controller  820  may be a circuit, an application-specific circuit, or at least one processor. Further, operations of the network entity may be realized by providing the memory device  830  storing the corresponding program code in an arbitrary component in the network entity. 
     The network entity may be any one of a base station (RAN, NG-RAN, eNB, gNB, NB), AMF, SMF, PCF, UDM, AUSF, AF, BSF, NEF, or UPF. 
     It should be noted that the constitution diagrams illustrated in  FIGS.  1  to  8   , diagrams of a control/data signal transmission method, operation procedure diagrams, and constitution diagrams are not intended to limit the scope of the disclosure. That is, all components, entities, or steps of operation described in  FIGS.  1  to  8    should not be construed as essential components for implementation of the disclosure, and the disclosure may be implemented within a range that does not impair the essence of the disclosure even by including only some components. 
     The operations of the base station or the terminal described above may be realized by providing a memory device storing the corresponding program code in an arbitrary component in the base station or the terminal device. That is, a controller of the base station or the terminal device may execute the above-described operations by reading and executing the program code stored in the memory device by a processor or a central processer (CPU). 
     Various components and modules of the entity, base station, or terminal device described in this specification may be operated using a hardware circuit such as a combination of a complementary metal oxide semiconductor-based logic circuit, firmware, software, and/or hardware and firmware and/or software inserted into a machine readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates, and application specific integrated circuits. 
     In the specific embodiments of the disclosure described above, components included in the disclosure were expressed in the singular or plural according to the presented specific embodiments. However, the singular or plural expression is appropriately selected for a situation presented for convenience of description, and the disclosure is not limited to the singular or plural components, and even if a component is represented in the plural, it may be formed with the singular, or even if a component is represented in the singular, it may be formed with the plural. 
     Embodiments of the disclosure disclosed in this specification and drawings present specific examples to easily describe the technical content of the disclosure and to help the understanding of the disclosure, and are not intended to limit the scope of the disclosure. That is, it is apparent to those of ordinary skill in the art to which other modifications based on the technical spirit of the disclosure may be implemented. Further, each of the above embodiments may be operated in combination with each other, as needed. For example, an embodiment of the disclosure and parts of another embodiment may be combined to operate a base station and a terminal. Further, the embodiments of the disclosure are applicable to other communication systems, and other modifications based on the technical spirit of the embodiments may also be implemented.