Patent Publication Number: US-2023147622-A1

Title: Apparatus and method for supporting continuity of edge computing service in mobile network

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 17/444,886, filed Aug. 11, 2021, now U.S. Pat. No. 11,553,560 issued Jan. 10, 2023, which is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2020-0102073, filed on Aug. 13, 2020, in the Korean Intellectual Property Office, the disclosure of which are herein incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     The disclosure relates to a method and an apparatus for providing an edge computing service to a user equipment (UE) in a mobile communication network and, more particularly, to a method and an apparatus for providing the continuity of an edge computing service to a UE. 
     2. Description of Related Art 
     To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. 
     The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. 
     In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. 
     In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
     The disclosure relates to a communication system, in which a terminal, for example, a user equipment (UE), may establish a data connection to an edge data network at a location close to the location thereof in order to use a low-latency or broadband service. Further, in the edge computing system, the terminal may access an application server run in an edge hosting environment or an edge computing platform operated by an edge enabler server of the edge data network, thereby being provided with a data service. Here, the terminal to access the edge computing system may be a mobile communication terminal that is provided with a mobile communication service. 
     A mobile communication terminal provides the mobility of a user. Thus, a UE may move along with a moving user. In this case, a mobile edge computing (MEC) system needs to provide the continuity of an edge computing system service to the UE. 
     However, a specific procedure for a method for providing the continuity of an edge computing service is not defined. 
     The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure. 
     SUMMARY 
     The disclosure discloses a procedure necessary for a user equipment to provide continuity of an edge computing service to the user equipment. 
     The disclosure discloses a procedure necessary for a network node to provide continuity of an edge computing service to a user equipment. 
     The disclosure discloses a procedure necessary in an edge computing system to provide continuity of an edge computing service to a user equipment. 
     According to an embodiment of the disclosure, a method by a user equipment (UE) for maintaining a mobile edge computing (MEC) service in a mobile communication system includes: receiving, from an access and mobility management function (AMF) in the mobile communication system, a protocol data unit (PDU) session modification command including first information instructing modification of a PUD session for the MEC service and valid time of the PDU session; transmitting, to the AMF, a PDU session modification command NACK message including second information indicating a wait until transmission of an ACK, when relocation of an application context corresponding to the PDU session is possible within the valid time of the PDU session; transmitting, to an MEC system providing the service, an application context relocation request message; and transmitting, to the AMF, a PDU session modification command ACK in response to receiving an application context relocation complete message from the MEC system, wherein the PDU session modification command and the PDU session modification command NACK message are non-access-stratum (NAS) messages. 
     According to an embodiment of the disclosure, a user equipment (UE) for maintaining a mobile edge computing (MEC) service in a mobile communication system includes: a modem configured to communicate with the mobile communication system and an MEC system; an application client configured to process data received from the MEC system; and an edge enabler client (EEC), wherein the EEC receives, from an access and mobility management function (AMF) in the mobile communication system, a protocol data unit (PDU) session modification command including first information instructing modification of a PUD session for the MEC service and valid time of the PDU session through the modem, controls the modem to transmit, to the AMF, a PDU session modification command NACK message including second information indicating a wait until transmission of an ACK, when relocation of an application context corresponding to the PDU session is possible within the valid time of the PDU session, controls the modem to transmit, to the MEC system providing the service, an application context relocation request message, and controls the modem to transmit, to the AMF, a PDU session modification command ACK in response to receiving an application context relocation complete message from the MEC system, and wherein the PDU session modification command and the PDU session modification command NACK message are non-access-stratum (NAS) messages. 
     According to the disclosure, it is possible to perform run time coordination between an application context information relocation operation for mobility support in an edge computing system and a user plane path management operation in a 3GPP network without a service level agreement between an edge computing server provider and a mobile communication network operator. In addition, an edge computing server does not need to subscribe to a user plane path change event notification to a 3GPP network function and may link a context information relocation operation between edge computing servers and a user plane path management operation of a 3GPP network without needing to reserve related resources. Accordingly, the disclosure may provide continuity of an edge computing service to a UE. 
     Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. 
     Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device. 
     Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
         FIG.  1    is a view illustrating a connection between a 3GPP network and an edge computing system network and movement of a terminal according to various embodiments of the disclosure; 
         FIG.  2    is a structural diagram illustrating interworking of a mobile communication network, an edge computing network, and an edge enabling layer according to various embodiments of the disclosure; 
         FIG.  3    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure; 
         FIG.  4    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure; 
         FIG.  5    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure; 
         FIG.  6 A  illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure, and  FIG.  6 B  illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure; 
         FIG.  7    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure; 
         FIG.  8    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure; and 
         FIG.  9    illustrates a functional block diagram of a network function, an EAS, or an EES according to various embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS.  1  through  9   , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device. 
     Hereinafter, principles of operating the disclosure will be described in detail with reference to the accompanying drawings. Terms used below are defined in view of functions in the disclosure and may thus be changed depending on a user, the intent of an operator, or the custom. Accordingly, the terms should be defined, based on the following overall description of this specification. 
     As used herein, terms referring to network entities, terms referring to entities of an edge computing system, terms referring to messages, terms referring to pieces of identification information, and the like are used for convenience of explanation. Therefore, the disclosure is not limited by the following terms, and other terms having equivalent technical meanings may be used. 
     Hereinafter, for convenience of explanation, terms and designations defined in 3GPP system standards are used in the disclosure. However, the disclosure is not limited by those terms and designations but may be equally applied to systems in accordance with other standards. 
     The disclosure described below relates to a communication system, in which a user terminal may establish a data connection to an edge data network at a location close to the location thereof in order to use a low-latency or broadband service. Further, disclosed is a technology for mobile edge computing that enables the user terminal to access an application server, for example, an edge application server, run in an edge hosting environment or an edge computing platform operated by an edge enabler server of the edge data network to use a data service. In particular, a technology related to communication between an edge computing system and a mobile network device for supporting mobility of the user terminal and procedures therefor will be described. 
     The disclosure provides an interworking method between an edge enabling layer related to mobility support and a NAS layer, which is a security layer of a mobile communication network. 
     The disclosure also provides a method of performing runtime coordination between an application function (EES/EAS) of an edge computing network and a specific node (SMF) of a mobile communication network through interworking between a terminal and the SMF. 
     In addition, the disclosure provides a method of providing information about user plane path management from an edge enabling layer to a mobile communication network, for example, a 3GPP network. 
     According to the disclosure, to perform run time coordination between an application context information relocation operation for mobility support in an edge computing system and a user plane path management operation in a 3GPP network, an edge computing server needs to directly interwork with the 3GPP network while serving as an application function. For this method, a service level agreement between an edge computing server provider and a network operator needs to be guaranteed in advance. Further, the edge computing server needs to always subscribe a user plane path change event notification to a mobile communication network, for example, a 3GPP network function. For this reason, the 3GPP network function and the edge computing server need to always reserve resources, causing overheads. To minimize reservation of resources and to reduce overheads for the edge computing server to directly interwork with the 3GPP network, the disclosure provides a method for terminal-based runtime coordination between the application context information relocation operation and the user plane path management operation. 
       FIG.  1    is a view illustrating a connection between a 3GPP network and an edge computing system network and movement of a terminal according to the disclosure. 
       FIG.  1    illustrates a service area  1  of a mobile network operator (MNO). The service area  1  of the mobile network operator may include edge data networks separated to provide an edge computing service to an electronic device. The respective edge data networks may include areas  10  and  20  for providing an edge computing service to an electronic device 1 (UE1)  50 . For example,  FIG.  1    shows an example in which a service area  10  of a first edge data network includes a first base station  111 , a second base station  112 , a third base station  113 , and a fourth base station  114 , and a service area  20  of a second edge data network includes a fifth base station  211  and a sixth base station  212 . 
     As illustrated in  FIG.  1   , two different user plane function (UPF) devices  121  and  122  are included in the service area  10  of the first edge data network including the first base station  111  to the fourth base station  1114 . In the following description, the UPFs  121  and  122  may be logically understood as one network device unless otherwise specified. Therefore, in the following description, the UPFs  121  and  122  will be referred to as a UPF device or a UPF. Further, as illustrated, the service area  20  of the second edge data network includes only one user plane function 1 (UPF1)  221 . As illustrated in  FIG.  1   , one edge data network may include one or more UPFs. 
     The service area  10  of the first edge data network may be an area managed by one edge enabler server  100 . The service area  20  of the second edge data network may be an area managed by another edge enabler server  200 . In this manner, the service areas  10  and  20  of the edge data networks may be configured as areas that can be managed by the edge enabler servers  100  and  200 . In another example, the service areas  10  and  20  of the edge data networks may be defined as areas of edge application servers connected to the edge enabler servers. In addition, as illustrated in  FIG.  1   , the service areas  10  and  20  of the edge data networks of a mobile communication system and an MEC system may be an area that enables a UE  50  to be served by at least one UPF (as indicated by reference numeral  20 ) or may be an area that enables the UE  50  to be served by two or more UPFs (as indicated by reference numeral  10 ). When associated with the mobile communication system, the service areas  10  and  20  of the edge data networks of the MEC system may be a single base station or a combination of two or more base station areas. Although  FIG.  1    shows that a service area of an edge data network is not only one base station area, one base station area may be a service area of one edge data network if necessary. 
     As illustrated in  FIG.  1   , the edge enabler servers  100  and  200  may be connected to the same or different edge application servers  101 ,  102 , and  201 . First edge application servers  101  and  201  and a second edge application server  102  may provide different edge computing services, respectively. A first application server  201  located in the service area  20  of the second edge data network that provides the same service as a first edge application server  101  located in the service area  10  of the first edge data network may provide an edge computing service to the electronic device  50  through the different edge enabler servers  100  and  200 . As illustrated in  FIG.  1   , the first edge application server  101  located in the service area  10  of the first edge data network may provide an edge computing service to the electronic device  50  connected to any one of the base stations  111 ,  112 ,  113 , and  114  located in the first edge data network. The second edge application server  102  may provide an edge computing service to the electronic device  50  connected to any one of the base stations  111 ,  112 ,  113 , and  114  located in the first edge data network. 
     The electronic device  50  may be a mobile terminal that can be provided with an edge computing service according to the disclosure and is capable of accessing a mobile communication network through a wireless network. The electronic device  50  may include a variety of mobile electronic devices, such as a smartphone, a tablet computer, a smartwatch, a game console, an automobile, a motorcycle, a bicycle, an airplane, and a ship, and/or various types of electronic devices capable of providing an IoT service. In a specific case, the electronic device  50  may be a device, such as a personal computer (PC). In this case, the personal computer needs to include a function of connecting to the mobile communication network. The electronic device  50  may have at least one edge computing service application  53  mounted according to the disclosure, may include an edge enabler client  52  according to the disclosure, and may include a mobile terminal  51 , for example, a communication layer, to perform a wireless communication function. The communication layer of the mobile terminal  51  may include a communication processor or a modem. Therefore, the mobile terminal  51  may be interchangeably referred to as a communication processor or a modem hereinafter. 
     Mounting the edge computing service application may mean that the application for receiving an edge computing service may be installed (or stored) in a memory (not shown in the drawing) of the electronic device  50 . Further, mounting the edge computing service application may mean that the application installed in the electronic device  50  is loaded into at least one processor to perform an operation for providing the edge computing service. 
     The edge enabler client  52  may be installed in the memory (not shown in the drawing) of the electronic device  50  in which the application for receiving the edge computing service is mounted. The edge enabler client  52  may be loaded into at least one processor instead of the installed application to perform at least part of an operation required by the edge computing service application. 
     The mobile terminal (MT)  51  may include a communication layer capable of communicating with a specific wireless communication network, for example, a 3GPP communication network, in a configured mode. The communication layer may include at least one communication processor and/or a modem, and may include a logic and at least one antenna for transmitting and receiving a wireless signal. 
     For convenience of explanation, the electronic device  50  is referred to as a user equipment (UE) hereinafter. Further, unless specifically limited, a terminal or a mobile terminal that is not designated by reference numeral  51  may be understood as an electronic device or a user equipment. 
     The base stations  111 ,  112 ,  113 ,  114 ,  211 , and  212  have a predetermined area for communicating with the UE  50  in a wireless communication mode established with the UE. For example, when the established wireless communication mode uses a mode of a 3GPP mobile communication network, the base stations  111 ,  112 ,  113 ,  114 ,  211 , and  212  may be base stations of the 3GPP mobile communication network. 
     The foregoing configuration of  FIG.  1    illustrates an edge computing deployment and a case of interworking with a 5G network among mobile communication networks. 
     The user plane function (UPF) devices  121 ,  122 , and  221  may serve as gateways transmitting a packet corresponding to user data transmitted or received by the UE. According to an embodiment of the disclosure, the UPFs  121 ,  122 , and  221  may be located physically and/or logically close to the edge enabler servers  100  and  200  to support an edge computing service. By configuring the UPFs  121 ,  122 , and  221  and the edge enabler servers  100  and  200  to be located physically and/or logically close to each other, a data packet to be provided to (or received from) a user may be transmitted directly to the edge data networks without passing through the Internet, thus reducing transmission. That is, low-delay transmission is possible. According to another embodiment of the disclosure, the UPFs  121 ,  122 , and  221  may also be connected with the edge enabler servers  100  and  200  via a data network connected to the Internet. 
     According to an embodiment of the disclosure, an edge computing system may include the edge enabler servers  100  and  200 , an edge configuration server  30 , and the edge enabler client (EEC)  52 . According to various embodiments of the disclosure, the edge enabler servers  100  and  200  may establish edge hosting environments  110  and  210  or edge computing platforms. Establishing an edge hosting environment or an edge computing platform means that an edge enabler server and at least one edge application server are connected or that at least one edge application server is running on a computing platform of an edge enabler server. Accordingly, the edge enabler servers  100  and  200  may know information about an edge application server running in the edge hosting environments or running on the edge computing platforms. 
     According to various embodiments of the disclosure, the edge enabler servers  100  and  200  may negotiate with the UE  50  and may connect an application client  53  running in the UE  50  and the edge application server in the edge hosting environments. According to various embodiments of the disclosure, as described above, the UE  50  supporting the edge computing system may have the edge enabler client  52  embedded or mounted therein. According to an embodiment of the disclosure, a negotiation between the UE  50  and the edge application server may be performed through interworking between the edge enabler client  52  in the UE  50  and the edge enabler servers  100  and  200 . According to an embodiment of the disclosure, a layer in which interworking between the edge enabler client  52  and the edge enabler servers  100  and  200 , such as the negotiation, is performed may be referred to as an edge enabling layer. The terminal or the UE  50  according to the disclosure may include an IoT device and a vehicle in addition to the aforementioned smartphone. 
     According to various embodiments of the disclosure, the edge configuration server  30  knows deployment information about the edge enabler servers  100  and  200  and may perform a function of transmitting configuration information for using an edge computing service to the UE  50 . According to an embodiment of the disclosure, the configuration information may include at least one of edge data network connection information, an edge data network service area, and edge enabler server connection information. Instead of defining an edge data network separately, a local data network in which the edge enabler servers and the edge application server exist may be considered to correspond to an edge data network. The edge configuration server may be referred to as an edge configuration server (ECS)  30 . 
     According to various embodiments of the disclosure, the edge data network connection information may include, for example, a data network name, single-network slice selection assistance information (S-NSSAI), or the like. Here, a network slice means that a device (or server) performing a specific function in a core network may be configured in the form of a slice. For example, a UPF may be configured with one server or network device. In another example, one server or network device may include two or more UPF slices therein. In yet another example, a UPF may be configured with two or more servers or may be configured with two or more network devices. A specific network slice may be logically understood as a network device that performs one specific function. 
     According to various embodiments of the disclosure, the edge data network service area (region) may include, for example, at least one or two or more cell lists, a tracking area list, and a network identifier (PLMN ID) of an operator. Further, the edge data network service area (region) may be a service area (region) of an edge enabler server configured by the edge enabler server in an edge data network. Alternatively, in an edge data network deployment scenario using a local access data network (LADN), the edge data network area (e.g., region) may be the same as an LADN service area. That is, the UE  50  may receive information about an edge enabler server connectable at a specific location from the edge configuration server  30 . When the edge configuration server  30  can know information about an edge application server running in an edge hosting environment of a specific edge enabler server, the edge enabler client  52  in the UE  50  may obtain the information from the edge configuration server  30 . According to various embodiments of the disclosure, the edge enabler server connection information may be, for example, a uniform resource identifier (URI) or an endpoint address, such as an Internet Protocol (IP) address. 
     According to various embodiments of the disclosure, the UE  50  may obtain information about a connectable edge enabler server based on specific location information, for example, a specific base station, a specific data network, or a specific physical location, from the edge configuration server  30 . According to an embodiment of the disclosure, when the edge configuration server  30  can know information about an edge application server running in an edge hosting environment of a specific edge enabler server, the UE  50  may also obtain the information through the edge enabler client  52 . 
     According to various embodiments of the disclosure, the edge application servers  101 ,  102 , and  201  may refer to third-party application servers running in the edge computing system. According to an embodiment of the disclosure, the edge application servers  101 ,  102 , and  201  may be third-party application servers running on an infrastructure provided by an edge hosting environment, and can provide a service at a location close to the UE  50 , thus providing a low-latency service. According to various embodiments of the disclosure, information about an upper layer of a service provided from an edge application server to the UE  50  may be referred to as an application context. For example, when a user uses a real-time game application, all pieces of information necessary to regenerate a screen and a play phase currently viewed by the user in the game may be included in the application context. For example, for the UE  50  to connect to another edge application server and to use an existing service without interruption, the application context needs to be relocated in the edge application server to be newly connected. In order to perform application context relocation, an edge application server capable of providing a service to an application running in the application client  53  of the UE  50  needs to be available. Availability of the edge application server in the edge data network may be determined according to whether the edge application server runs in the edge hosting environment and the state of the edge application server. 
     The edge enabler servers  100  and  200 , the edge application servers  101 ,  102 , and  201 , and the edge configuration server  30  in the edge computing system may obtain terminal-related information from the mobile communication system. In a specific example, the 3GPP system may include a network exposure function (NEF) device that is a network entity exposing a network function. In this case, at least one entity among entities forming the edge computing system may include an application program interface (API). The entity of the edge computing system including the API may obtain the terminal-related information using the API. 
     According to various embodiments of the disclosure, as described above, the UE  50  may include the application client  53 , the edge enabler client  52  that connects the application client  53  and an edge computing service, and the mobile terminal (MT)  51  connecting to the mobile communication system. According to various embodiments of the disclosure, an application of the UE  50  is an application provided by a third party and may refer to a client application program that is run in the UE  50  for a specific application service. Two or more applications may run in the UE  50 . According to an embodiment of the disclosure, at least one of the applications may use a multi-access edge computing (MEC) service. The edge enabler client  52  in the UE  50  may refer to a client that performs an operation in the UE  50  necessary to use an edge computing service. According to an embodiment of the disclosure, the edge enabler client  52  may identify which application can use the edge computing service and may perform an operation of connecting a network interface so that data of the application client of the UE  50  can be transmitted to an edge application server that provides the edge computing service. According to an embodiment of the disclosure, the UE  50  may configure a wireless channel with a base station through the mobile terminal  51  to use the edge computing service. The wireless channel may be configured in a communication layer, for example, a 3GPP communication layer, of the mobile terminal  51 . According to an embodiment of the disclosure, the communication layer of the mobile terminal  51  may serve to establish a wireless connection for data communication, to register the UE  50  in the mobile communication system, to establish a connection for data transmission to the mobile communication system, and to transmit or receive data. 
     Network functions (NFs) running in the 3GPP network illustrated in  FIG.  1    or to be described below will be described as “devices.” However, each NF may be actually configured in the form of an instance in one physical server. 
     In the disclosure, one instance may be configured as specific software, and the software performing one instance operation may be configured to run on one physical hardware device. 
     According to another embodiment of the disclosure, one instance may run in two or more hardware devices, for example, different racks forming two or more servers or one server, rather than in one physical hardware device. 
     According to yet another embodiment of the disclosure, two or more different instances may run on one physical hardware device, for example, one server. In this case, at least some of the NFs illustrated in  FIG.  1    may run in the same physical hardware. 
     According to yet another embodiment of the disclosure, two or more instances performing the same function may run in one physical hardware device. When two or more instances performing the same function run in one physical hardware device, the respective instances may control and/or serve different objects, for example, different UEs. When one instance performs a specific operation of controlling the same object, for example, the same single UE, and/or providing a service to the same object, the same single UE may have different identifiers for different services and/or controls. 
     In the following description, one NF will be described as one device only for convenience of explanation. However, as described above, each NF may be configured as one instance or two or more instances, and all of these cases may be included herein. Further, other NFs not described above will be described as devices in accordance with the foregoing description. However, each NF may be actually configured as one instance or two or more instances. 
       FIG.  2    is a structural diagram illustrating interworking of a mobile communication network, an edge computing network, and an edge enabling layer according to various embodiments of the disclosure. 
     First, for convenience of explanation, a UE is designated by reference numeral  300  in the following description. However, the UE may be the same UE designated by reference numeral  50  described in  FIG.  1   . In the internal block configuration of the UE  300  illustrated in  FIG.  2   , only components for explaining interworking of the edge enabling layer are illustrated. Accordingly, it will be apparent to those skilled in the art that the UE  300  may have components other than the components illustrated in  FIG.  2   . For example, the UE  300  may include an antenna for connecting to a mobile communication network and/or a wireless communication network and at least one RF module. The UE  300  may further include a memory, and may additionally include an input device and an output device for interfacing with a user. 
     Referring to  FIG.  2   , the UE  300  may include an application processor  310  and a communication processor  330 . The communication processor  330  may include a non-access-stratum (NAS) control plane  331  therein. A NAS control plane operation may include a series of procedures required for the UE  300  to initially connect to the mobile communication network, to perform an authentication procedure, to generate a PDU session, to connect to a data network, and to exchange user plane data. For example, the NAS control plane operation includes an operation of receiving a signaling message (e.g., a PDU session modification command) related to occurrence of an event related to a user plane path from a network device (e.g., a session management function) that manages a PDU session and transmitting a necessary response message (e.g., a PDU session modification command ACK). Alternatively, the UE  300  may transmit signaling to a specific node or device of the network through the NAS control plane in order to request PDU session generation. The communication processor  330  may configure a first PDU session  500  with the mobile communication network, for example, a 5G network  400 . The first PDU session  500  may be connected to a first PDU session anchor (PSA1)  401  and a second PDU session anchor (PSA2)  402 . When there are two or more PDU session anchors for one PDU session, a PDU session anchor may be changed in the mobile communication network due to movement of the UE  300 . 
     A first application (Application #1)  301  for receiving an edge computing service may be mounted in the application processor  310  of the UE  300 . The first application  301  being mounted may mean a state in which a program is stored in a memory in the UE  300  and the first application can run on an operating system (OS). 
     The application processor  310  of the UE  300  may include a TCP/IP stack  320  in an OS kernel. The TCP/IP stack  320  may include a third layer (Layer 3)  321  and a fourth layer (Layer 4)  322  and may include an edge enabler client  52  thereabove. The edge enabler client  52  employs the same reference numeral as that described in  FIG.  1    in view of a correspondence therebetween. The third layer  321  may perform an operation necessary to enable an application client  53  and an edge application server (EAS) to communicate using an Internet protocol. Additionally, in the disclosure, the third layer  321  may serve to receive a router advertisement (RA) message including IP address configuration information and to determine and report the meaning of the information included in the RA message to an upper layer. The fourth layer  322  may perform an operation necessary to reliably and efficiently transmit data generated from the application client  53  to the edge application server. The application client  53  may be the first application (Application #1)  301 . 
     Next, edge data networks may include two or more different edge data networks.  FIG.  2    illustrates two different edge data networks EDN  1  and EDN  2 . A first edge data network EDN  1  is shown to include the first edge enabler server  100  and the first edge application server  101  described with reference to  FIG.  1   . Here, as described above in  FIG.  1   , since the UE  300  can move to a second edge data network EDN  2 , the edge enabler server  100  and the edge application server  101  of the first edge data network EDN  1  are marked with “source,” and an edge enabler server  200  and an edge application server  201  included in the second edge data network EDN  2  are marked with “target.” 
     As illustrated in  FIG.  2   , a 3GPP network  400  provides a user plane (UP) path management event notification application program interface (API) that an EAS or an EES can use. When a UP path management event (e.g., a change of a PDU session anchor user plane function (PSA UPF)) occurs due to movement of the UE  300 , the occurrence of the event may be notified to the EESs  100  and  200  or the EASs  101  and  201  outside the 3GPP network  400  through the API. To support this operation, a service level agreement is required between a provider of the EESs  100  and  200  or the EASs  101  and  201  that desire to receive a notification and a network operator and it is necessary to identify availability of the API in advance and to subscribe to a notification service. 
     Without the EESs  100  and  200  or the EASs  101  and  201  using the API provided by the 3GPP network  400  as illustrated in  FIG.  2   , the same function may be provided through an operation in the UE  300 . It is possible to detect occurrence of a UP path management through interworking of the edge enabler client (EEC)  52  of an edge enabling layer in the UE  300  and the NAS layer control plane  331  of the communication processor  330 , for example, a modem, and to perform an operation required by each of the edge enabling layer and a NAS layer. 
     Each network function (NF) described herein may run in a specific server or may be configured as one separate independent device. When an NF is configured in one server, two or more NFs may be configured in one server. When two or more NFs are configured in one server, two or more identical NFs may exist in one server. In this case, the NFs may be one method for configuring a network slice. When one NF or two or more NFs are configured in one server, a program for performing operations of the NFs may be mounted in the server. Further, one NF may be configured to run on two or more interworking servers. 
       FIG.  3    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure. 
     Referring to  FIG.  3   , in operation S 301  (Step 1), a session management function (SMF)1  441  may determine that user plane function (UPF) and/or SMF relocation needs to be performed based on movement of the UE. 
     In operation S 302  (Step 2), the SMF  441  may invoke and transmit a Namf_Communication_N1N2MessageTransfer message to an access and mobility management function (AMF)  421 . The message may include a PDU session ID, an SMF Reallocation requested indication, and an N1 SM container (PDU session modification command (cause, PDU session address lifetime, and UE upper layer coordination requested indication)). Here, the SMF1  441  may configure and operate a PDU session release timer according to a PDU session address lifetime value. 
     The configured value of the timer may be configured using a value provided from an edge enabler server  100  or  200  or an edge application server  101  or  201  or using a value provided from the UE  300  (e.g., the edge enabler client  52 ). In another method, when configuring the PDU session release timer, the SMF1  441  may determine whether to configure the value of the timer to be greater than a normal value based on a local configuration instead of being provided with the value from the edge enabler server  100  or  200  or the edge application server  101  or  201  depending on whether the relocation is performed. It is possible to determine and reconfigure whether to perform the relocation by the UE  300  transmitting a relevant indication to the SMF1  441  (via an ACK of the PDU session modification command, a relevant operation of which will be described in detail with reference to Step 3b) or depending on an application to which a corresponding session is bound. Information included in the Namf_Communication_N1N2MessageTransfer message transmitted from the SMF  441  to the AMF  421  is described in detail as follows.
         An SMF Reallocation requested indication: whether SMF Reallocation is requested. This indication may be used for the AMF  421  to determine whether to perform an operation related to SMF relocation.   A PDU session modification command (cause in PDU session modification command): information for instructing the UE  300  to modify a PDU session, which is included in the N1 SM container and may be transmitted to the UE  300 . PDU session re-establishment to the same DN is required.   A UE upper layer coordination requested indication: when a PDU session corresponding to the PDU session ID is connected to an edge data network (EDN), an indication of reporting this information and of possibly requiring interworking with the upper layer (edge enabling layer) may be included and transmitted in the N1 SM container. Instead of separately configuring this indication, it is possible to include and transmit the information in a cause parameter of the PDU session modification command. For example, information about whether support for edge application server or edge enabler server relocation can occur may be included in the cause parameter.       

     In operation S 303   a  (Step 3a), the AMF  421  may transmit the PDU session modification command to the UE  300  using the NAS message (N1 SM container) received from the SMF1  441 . 
     In operation S 303   a -E 1 , the UE  300  may perform the following operations instead of immediately transmitting a response to the received NAS message.
         A communication processor (e.g., a modem  51 )  330  of the UE  300  may transmit a release timer value or a PDU session address lifetime value included in the NAS message to an EEC  52  in the UE  300 .   The EEC  52  may check (identify or determine) whether application context transfer (relocation/migration) can be performed before the timer expires and may transmit a negative response to the modem  51 .   The EEC  52  may provide the timer to the S-EES  100 , the S-EAS  101 , the T-EES  200 , or the T-EAS  201  so that the application context relocation is completed before the timer expires. Upon receiving the timer, the edge computing servers may determine (identify or judge) whether a required operation can be completed before the timer expires and may then transmit a negative response to the EEC  52 . Upon receiving the negative response, the EEC  52  may report the negative response to the modem  51  or  330 , and the modem  51  or  330  may request the SMF1  441  to delay a UP path management operation. Here, as described above, the modem  51  or  330  may be interchangeably used with the communication processor or a mobile terminal (MT), all of which may refer to a processor capable of communication with a mobile communication network or a wireless communication network. Therefore, component designated by at least one of reference numeral  51  or  300  should be equally interpreted. If necessary, the EEC  52  may also transmit the corresponding value and information about whether a UP path change event occurs to an associated application client (AC)  53  or  301  through an EDGE-5 interface. Here, the application client  53  or  301  may be an application receiving an MEC service and may employ either or both of the above reference numerals.   In addition, the following pieces of information may be provided from the modem  330  to an upper layer (edge enabling layer, EEC, AC, and the like) in the UE  300 .   Information indicating that application context relocation (ACR) is required may be transmitted from the modem  51  to the EEC  52  and the application client  53  (to the application client  53  via the EEC  52  (EDGE-5)).   Timer for transmitting PDU session modification command ACK: When the timer expires, a lower layer (e.g., the modem) may transmit, to the EEC  52 , an indication that a PDU session modification command ACK is transmitted to the SMF1  441 .       

     As described above, after transmitting the necessary information to the EEC  52  of the upper layer, the modem  330  may configure a PDU session modification command response transmission timer value and may operate a transmission timer. Operating the transmission timer is for transmitting a response to a 3GPP network without waiting too long when there is no response from the upper layer. The PDU session modification command response transmission timer value may be configured based on the PDU session address lifetime value received from the network. 
     In operation S 303   a -E 2 , the modem  51  of the UE  300  may transmit a NAS message relating to PDU session modification command NACK or rejection to the SMF1  441  (here, the message may be transmitted through the AMF  421 ). The following pieces of information may be included in the PDU session modification command NACK or rejection message. 
     (1) Information indicating waiting until transmission of an ACK may be included in the cause. 
     This is for reporting that a PDU session modification command ACK may be transmitted later. This information may be used as an indication of a request of the SMF1  441  to wait for UPF configuration or activation until the transmission of the ACK. 
     (2) Preferred (or suggested) timer for PDU session release that may be determined by the modem  51  based on a PDU session release timer value suggested by the UE  300  or information provided from the EEC  52  or the application client  53  and may be included in the response to the PDU session modification command. 
     (3) Indication that the SMF is not to be changed: the indication may include indication information about a request to continue to use the SMF previously associated with the UE  300 . 
     For reference, although a negative response (NACK) or a rejection message may be transmitted in response to the PDU session modification command in operation S 303   a -E 2  as described above, the same operation (requesting a UPF configuration or activation delay or transmitting a suggested timer value) may be performed to the SMF1  441  while transmitting a positive response (ACK) and transmitting the same parameter as above. 
     In operation S 303   a -E 3 , the EEC  52  needs to enable context relocation in the S-EAS or the S-EES to be completed before transmitting a PDU session modification command ACK from the UE  300  or performing a UE-initiated PDU session establishment request with a new UPF. 
     (1) The EEC  52  receiving a notification from the modem  51  may check (identify or determine) whether there is information that needs to be relocated to ensure service continuity, such as application context information or transport layer context information stored in the S-EAS  101 , the S-EES  100 , or the application client  53 , and whether relocation is necessary/possible. To this end, the EEC  52  may identify and determine (judge) an EAS service continuity support attribute in an EAS profile or may identify application client profile information. 
     As a result of the identification, when context relocation or transfer is not required, the EEC  52  may immediately notify the modem  330  that the context relocation or transfer is not required, thereby transmitting a response to the SMF1  441  so that UP path configuration/activation may be immediately performed (perform Step 3b). For example, the EEC  52  may transmit context relocation un-required indication information to the modem so that the modem  51  may immediately transmit a response (PDU session modification command ACK or PDU session modification command complete) to the PDU session modification command to the SMF1  441  via a NAS message. 
     As a result of the identification, when the context relocation or transfer is required, the EEC  52  may interwork with an edge configuration server (ECS)  30  to be provided with new T-EES information as necessary or may utilize information previously stored in the EEC  52 . The EEC  52  may perform a T-EAS discovery procedure based on available T-EES information. The EEC  52  may perform a T-EES discovery and may then transmit a context relocation request message including obtained T-EAS information to the S-EES  100  or may request the S-EES  100  to perform a T-EES discovery without performing a T-EAS discovery procedure in advance. As a result of this procedure, the S-EES  100  may notify the S-EAS  101  and the T-EAS  201  that context information corresponding to the UE  300  needs to be relocated. Further, the S-EES  100  may give a command (or control or instruction) to perform T-EAS context relocation from the S-EAS  101 . As necessary, context information stored in the S-EES  100  may also be relocated to the T-EES  200 . After relocation of context information stored in the S-EAS  100  and the T-EES  200  is completed, the S-EES  100  may notify the EEC  52  that the relocation is completed (context relocation response or context relocation complete notification). 
     In operation S 303   a -E 4 , the application client  53  in the UE may transmit a context relocation complete notification to the lower layer. 
     When recognizing that the relocation is completed by receiving the context relocation response or the context relocation complete notification, the EEC  52  (the completion of the relocation may be notified to the application client  53  depending on application client  53  and EAS configuration methods and accordingly the EEC  52  may be notified of the completion of the relocation from the application client  53 ) may perform an operation of notifying the modem  51  that the relocation is completed. 
     The EEC  52  may transmit a notification of the completion of the relocation to the lower layer (e.g., the modem  51 ) and the application client  53  in the UE  300 . 
     In operation S 303   b , the modem may be notified of the completion of the relocation from the EEC  52  and may transmit a NAS message (PDU session modification command ACK) to the AMF  421 . The modem  51  may transmit the PDU session modification command ACK when receiving the notification of the completion of the relocation from the EEC  52  or when the timer configured in operation S 303   a -E 1  expires. The NAS message may be transmitted from the modem  51  of the UE  300  to the AMF  421 . 
     In operation S 303   c , the AMF  421  may transmit the NAS message, received from the UE  300 , to the SMF1  441 . 
     In operation S 303   d , the SMF1  441  may transmit a response to the message received from the AMF  421  to the AMF  421 . 
     When the NAS message received from the UE  300  through the AMF  421  includes the fact that the relocation has been completed or there is no negative response, the SMF1  441  may prepare to perform an operation of performing activation (new UPF activation) of a new user plane path in which the configuration is performed. Further, the SMF  441  may wait to receive a PDU session release request message from the UE  300  without waiting until the PDU session release timer expires. When the PDU session release timer expires, an old PSA UPF (e.g.,  431 ) may immediately release a resource for the UE  300 . 
     When the negative response of the UE  300  is included in the NAS message, the SMF1  441  may stop the PDU session release timer and may maintain an existing user plane path rather than releasing the same. 
     In operation S 304 , when being notified the completion of the relocation from the EEC  53  and completely transmitting the PDU session modification command ACK to the SMF1  441 , the modem  51  of the UE  300  may perform a UE-initiated PDU session establishment request to configure a new user plane path to the T-EAS  201  and the T-EES  200 . Here, a new SMF may be selected and a UPF2  432  may be configured and activated. 
     In operation S 305 , the UE  300  may continue communication between the T-EAS  201  and the application client through the newly configured/activated user plane path. 
     In operation S 306 , after identifying that the communication between the application client  53  and the T-EAS  201  is successfully performed and that data is successfully transmitted and received via an uplink and a downlink, the UE  300  may perform a procedure for PDU session release from the previous UPF1 ( 431 ). 
       FIG.  4    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure. 
     Respective operations S 401 , S 402 , S 403   a , and S 403   a -E 1  are performed respectively in the same manner as operations S 301 , S 302 , S 303   a , and S 303   a -E 1  described above aforementioned embodiment of  FIG.  3   . Therefore, a redundant description will be omitted. 
     In operation S 403   a -E 2 , upon receiving a PDU session modification command and related information from a modem  51 , an EEC  52  may instruct (notify or request) an application client (edge-aware application)  53  to perform application context relocation. If necessary, before transmitting the instruction to perform the application context relocation, the EEC  52  performs a service provisioning operation (obtaining T-EES information from an ECS  30 ) and a T-EAS discovery operation with respect to a T-EES (e.g., the T-EES  200  described in  FIG.  1    to  FIG.  3   ) obtained from the ECS  30 . Here, the T-EAS discovery operation with respect to the T-EES  200  may be an operation of the EEC  52  requesting (instructing) the T-EAS discovery operation from the T-EES  200  and an operation of receiving a response thereto. For example, a T-EAS  201  may not exist in the T-EES  200  or may be in an inactive state. In this case, when receiving a T-EAS discovery request (instruction) from the EEC  52 , the T-EES  200  may activate the T-EAS  201  in response or may provide a response that there is no T-EAS. In another example, there may be a case where the T-EAS  201  is activated in the T-EES  200  but cannot accommodate a service anymore. In this case, the T-EES  200  may activate a new T-EAS  201  as a response or may transmit a response message of being impossible to accommodate (including rejection). In the following description, it is assumed that the EEC  52  receives a positive response to the discovery of the T-EAS  201  from the T-EES  200 , receives a response that the T-EAS  201  exists, or receives a response that the T-EAS  201  can accommodate a service. 
     The EEC  52  may transmit T-EAS address information or the like obtained through the T-EAS discovery operation to the application client  53 . Upon receiving this information, the application client  53  may provide information about an S-EAS (e.g., the S-EAS  201  described in  FIG.  1    to  FIG.  3   ) to the T-EAS  201  through the T-EAS address information and may request application context retrieval. After receiving the request, the T-EAS  201  may receive application context from the S-EAS  101  and may then notify the application client  53  of completion of context relocation, and the application client  53  may transmit this fact to the EEC  52 . Although  FIG.  4    illustrates only operations performed between the AC  53  and the EEC  52  among the foregoing operations, all or at least part of the foregoing operations may be included. 
     In operation S 403   a -E 3 , the EEC  53  may notify the modem  51  of the completion of the application context relocation. The modem  51  waits without transmitting a PDU session modification command ACK until being notified of the completion of the application context relocation. 
     The modem  51  may be notified of the completion of the application context relocation and may perform operation S 403   b . Operations, for example, operation S 403   c , operation  403   d , and operation S 404  to operation S 406 , following operation S 403   b  are also those of  FIG.  3    described above. The operation may be the same as operation S 303   c , operation  303   d , and operation S 304  to operation S 306  of  FIG.  3    described above. Since these operations are performed in the same procedure as described above, a redundant description will be omitted. Through the above operations, UP path management for the UE  300  may be completed. 
       FIG.  5    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure. 
     Respective operations S 501 , S 502 , S 503   a , and S 503   a -E 1  are performed in the same manner as operations S 301 , S 302 , S 303   a , and S 303   a -E 1  described above aforementioned embodiment of  FIG.  3   . Therefore, a redundant description will be omitted. 
     In operation S 503   a -E 2 , an EEC  52  may immediately transmit a response to a notification from a modem  51  and may provide a PDU session address lifetime value. For example, when the EEC  52  determines that an application context relocation operation needs to be performed, the EEC  52  may request update of a PDU session release timer while providing a timer value greater than a PDU session address life timer value of an SMF1  441  to the modem  51 . 
     After receiving (or in response to receiving) a PDU session modification command message in previous operation S 503   a , the modem  51  may configure a suggested (preferred) timer value in a PDU session modification command ACK message and may immediately transmit the message to the SMF1  441  through an AMF  421  in response to the NAS message in operation S 503   b . Upon receiving the message, the AMF  421  may transmit the NAS message received from the modem  51  of the UE  300  to the SMF1  441  in operation S 503   c.    
     In operation S 503   a -E 3 , the EEC  52  may notify (or instruct, direct, or transmit) an application client  53  that application context relocation is necessary and may perform a related procedure simultaneously with or after previous operation S 503   a -E 2 . For example, the EEC  52  may sequentially perform service provisioning and EAS discovery operations or may transmit a context relocation request message to an S-EES (e.g., the S-EES  100  described in  FIG.  1    to FIG.  3 ). Although  FIG.  5    illustrates only operations performed in the UE  300 , the foregoing operations may be performed together, previously, or subsequently. 
     In operation S 503   a -E 4 , after an application context relocation procedure is completed (a notification of completion of the procedure may be received from the S-EES  100 , the T-EES  200 , or the application client  53 ), the EEC  52  may notify the modem  51  of the completion of the procedure (or provide a notification). 
     In operation S 504 , after receiving the notification of the completion of the application context relocation from the EEC  52 , the modem  51  may transmit a request message for performing a UE-initiated PDU session establishment procedure to the SMF1  441  through NAS signaling. For continuity of a service, the modem  51  may wait until receiving a notification of the completion of the application context relocation from the EEC  52  of an upper layer without performing the UE-initiated PDU session establishment procedure. As described above, since operation S 505  and operation S 506  are respectively the same as operation S 305  and operation S 306  described above with reference to  FIG.  3    according to the aforementioned embodiments, an additional description will be omitted. 
     In addition to the embodiment described with reference to  FIG.  5   , the modem  51  and the EEC  52  in the UE  50  may operate as follows. The modem  51  and the EEC  52  may perform NAS control plane operation and an edge enabling layer operation in parallel. Accordingly, the UE  50  may perform the application context relocation procedure in an edge enabling layer while performing an operation of generating a new PDU session. Here, even though the operation of generating the new PDU session is completed first, the UE  50  may wait until the application context relocation procedure is completed and may then start to use the new PDU session. A specific operation is as follows. The modem  51  may receive the PDU session modification command (operation S 503   a ), may transmit the PDU session modification command ACK (operation S 503   b ), and may perform the operation of generating the new session by transmitting the UE-initiated PDU session establishment request message (operation S 504 ) in parallel with performing the application context relocation procedure through the EEC  52  in the edge enabling layer. After the new PDU session is generated (after operation S 504  is completed), the UE  50  may identify the completion of the application context relocation procedure through the EEC  52  and may then perform communication with the application client  53  and the T-EAS  201  through the newly generated PDU session (operation S 505 ). 
       FIG.  6 A  illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure, and  FIG.  6 B  is a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to yet another embodiment of the disclosure. 
       FIG.  6 A  and  FIG.  6 B  are signal flowcharts including an operation in which an operating system kernel  333  including a network stack in the UE  300  receives new IP address configuration information through a router advertisement (RA) message and the network stack provides the information included in the received message to an AC  53  or an EEC  52 . Here, the network stack is a device that manages operations related to third and fourth layers. 
     In the following description, the flow of  FIG.  6 B  will be described after the flow of  FIG.  6 A , and these operations may be performed sequentially. Therefore, in the following description, for convenience of explanation,  FIG.  6 A  and  FIG.  6 B  are not separately designated but will be collectively referred to as  FIG.  6   . 
     In one embodiment, a method of determining whether application context relocation is necessary using a procedure for a change of session and service continuity (SSC) mode 3 PSA with an IPv6 multi-home PDU session is provided. 
     Operation S 601  to operation S 605  may correspond to a procedure in which a 3GPP network function (NF) device detects a need for UPF relocation and performs an operation for new UP path configuration. For example, in operation S 601 , an SMF  441  may determine that UPF relocation needs to be performed when one of various preset reasons occurs. In operation S 602   a , based on this determination, the SMF  441  may transmit and receive an N4 session establishment request/response with a UPF2  432 , which is a new UPF. In operation S 602   b , the SMF  441  may perform an operation for session management policy modification with a PCF  451 . Accordingly, in operation S 603 , the SMF  441  may select a branching point (BP) UPF  433 . When the BP UPF  433  is selected, the SMF  441  may configure a configuration for the BP UPF  433  and the UPF2  432  in operation S 604 . When the configuration is completed, the SMF  441  may configure a UP path of a base station ((R)AN)  114  that communicates with the UE  300 , the BP UPF  433 , a UPF1  431  as an existing UPF, and the new UPF2  432  in operation S 605 . 
     In operation S 606 , the SMF  441  may transmit a new IP prefix address (IP@2) corresponding to the UPF2  432  on the newly configured UP path to the UE  300 . Specifically, new IP prefix information may be input to the operating system kernel  333  including the network stack in the UE  300 , and may be provided from the network stack to the AC  53  or the EEC  52 . Here, the network stack may be a block (or device) that manages the operations related to the third and fourth layers. The SMF  441  may transmit the new IP prefix address (IP@2) to the UE  300  through a router advertisement (RA) via the UPF2  432 . 
     In operation S 607 , the SMF  441  may transmit an RA for updating an existing IP prefix address (IP@1) to the UE  300  via the UPF1  431 . Here, in the RA for updating the existing IP prefix address, a preferred lifetime field is configured to be a value of 0, and a valid lifetime field may be configured to be a valid value (how long the SMF  441  maintains the existing IP prefix address (IP@1)). When determining the value of the valid lifetime field, a value suggested by a device (e.g., an EES (reference numeral  100  or  200  described in  FIG.  1    to  FIG.  3   ) or an EAS (reference numeral  101  or  201  described in  FIG.  1    to  FIG.  3   )) of an edge enabling layer may also be used. For example, the EES  100  or  200  or the EAS  101  or  201  may specify the UE  300  including the EEC  52  providing the service with a UE ID and may transmit an application function request message to a mobile communication network, for example, a 3GPP network, thereby suggesting a lifetime timer value in the mobile communication network. 
     When receiving the RA of operation S 606  and operation S 607 , a modem  51  in the UE  300  or the operating system kernel  333 , which is an IP layer of an application processor  310 , may notify the application client  53  or  301  or the EEC  52  in an upper layer of the RA in operation S 608 .
         According to an RA notification method, the IP layer or the modem  51  may directly transmit a notification of the RA to the EEC  52  (operation S 608   a ), or the IP layer or the modem  51  may transmit a notification of the RA to the application client  53 , after which the application client  53  transmit the notification to the EEC  52  through EDGE-5, thereby reporting that application context relocation may be necessary (operation S 608   b ).   The message reported to the EEC  52  or AC  53  may include timer information indicating when the existing UP path (UPF1) or the old IP prefix (IP@1) is released.       

     In operation S 609 , the EEC  52  or the application client  53  may determine a need to perform application context relocation based on operation S 607  and may start a related procedure.
         The EEC  52  may detect the need to perform application context relocation and may start a context relocation-related procedure by performing a context relocation request or performing a service provisioning/EAS discovery operation.   When the message reported to the EEC  52  or AC  53  includes the timer information indicating when the existing UP path (UPF1) is released, the following operations may be performed.       

     (1) The EEC  52  or the AC  53  may check a timer and may determine whether context relocation can be completed before the predetermined timer expires. 
     (2) A new timer value may be suggested to the modem  51  so that the existing UP path (UPF1) is not released, and accordingly a NAS message may be transmitted to the SMF  441  (a UPF1 release or old IP prefix (IP@1) release timer extension request or a terminal-suggested release timer may be included). The SMF  441  may receive the timer value suggested by the UE  300  and may delay the release time of the existing old IP prefix (IP@1) or the UPF1  431 . 
     After completing the context relocation procedure, the EEC  52  may interwork with the application client and a lower layer to transfer existing application data traffic to the new IP prefix (IP@2) in operation S 610 . The EEC  52  may transmit a NAS message to the SMF  441  through the modem  51  so that the existing UP path (UPF1) is not released until the application data traffic is successfully transferred (an old UPF release timer extension request or a terminal-suggested release timer may be included). When starting communication with a T-EAS (e.g., the T-EAS  201  described in  FIG.  1    to  FIG.  3   ) through the new IP prefix address, implicit release from the existing IP prefix (IP@1) may be performed. In operation S 610 , the AC  53  and/or the EES  52  may interwork with the operating system kernel  333  to transmit and receive the message. 
     After operation S 610 , an operation related to UP path management may be performed between the UE  300 , the UPF1  431 , and the UPF2  432 . Further, the operation related to UP path management may also be performed between a RAN  114 , the SMF  441 , the UPF1  431 , and the AMF  421 . 
     When the operation related to UP path management is completed, data transmission/reception may be performed through the UP path configured between the UE  300  and the UPF2  432 . 
       FIG.  7    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure. 
     The aforementioned embodiments of  FIG.  7    illustrates a method in which an edge enabling layer device provides a timer value related to UP path management to a mobile communication network, for example, a 3GPP network. 
     In operation S 701 , an S-EES  100  of the UE  300  may receive an early notification message for a UP path change from a 3GPP network  400 . As illustrated in  FIG.  7   , the early notification message for the UP path change may be transmitted, for example, by an SMF among various network function devices of the 3GPP network  400 . 
     Upon receiving the early notification message for the UP path change from the 3GPP network  400 , the S-EES  100  may transmit the early notification message for the UP path change to the UE  300  in operation S 70 E1. Upon receiving the early notification for the UP path change, an EEC  52  of the UE  300  may transmit a response to the S-EES  100  while providing a suggested (preferred) timer value for UP path management (e.g., a PSA release timer value or an old IP prefix release timer value). 
     In operation S 70 E2, the S-EES  100  may transmit a notification for context relocation to be required to an S-EAS  101  in response to the received early notification from the 3GPP network. 
     In operation S 70 E3, the S-EAS  101  may provide a suggested (preferred) timer value for UP path management (e.g., a PSA release timer value or an old IP prefix release timer value) or estimated time required for application context relocation while transmitting an acknowledgment of the notification received from the S-EES  100  to the S-EES  100 . 
     In operation S 70 E4, the S-EES  100  may provide the timer value provided from the UE  300  or the S-EAS  101  in the previous operation while transmitting a response (AF acknowledgement) message to the early notification to the 3GPP network  400 . The SMF of the 3GPP network  400  provided with the timer value may use the timer value received from the S-EES  100  to configure an old PSA release timer, a PDU session address lifetime, an old IP prefix release timer, or the like when performing UP path management. 
     In operation S 704 , the S-EES  100  may determine a T-EES. To determine the T-EES, various factors may be used. For example, the S-EES  100  may determine the T-EES  200  by asking an ECS  30  using movement information and identification information about the UE  300 , edge computing service identification information, or the like or based on information provided by the UE  300 . 
     In addition, the S-EES  100  may receive a late notification message for a UP path change from the 3GPP network  400 . 
     After receiving the late notification message for the UP path change from the 3GPP network  400 , the S-EES  100  may transmit a timer value while transmitting a response ACK message to the notification message in operation S 70 E5. If necessary, even though the suggested (preferred) timer value for UP path management has already been transmitted in previous operation S 70 E4, the timer value may be transmitted again (the timer value may be modified and transmitted again for reconfirmation or updating). 
     In operation S 705 , the S-EES  100  may transmit a context relocation request message to the T-EES  200 . In response, the T-EES  200  may check (or identify or verify) availability of a T-EAS  201  and may select a T-EAS  201  to which context can be relocated in operation S 706 . In selecting the T-EAS  201 , when there is only one T-EAS  201 , the T-EAS may be selected, and when there are two or more selectable T-EASs, one of the T-EASs may be selected. When the selection of the T-EAS is completed, the T-EES  200  may transmit a context relocation response message to the S-EES  100  in operation S 707 . The context relocation response message may include at least one of the availabilities of the T-EAS and information about the selected T-EAS. 
     After the context relocation operation is completed, the S-EES  100  may transmit an AF request message for providing N6 routing information to be applied to a newly configured UP path to the 3GPP network  400  in operation S 70 E6. The N6 routing information to be included in the AF request message may include routing information that needs to be applied to a UP path connected to the T-EAS  201  and the T-EES  200 . Therefore, the information may be included in the AF request message provided by the S-EES  100  from the T-EES  200  or the T-EAS  201  and provided to the 3GPP network  400  (e.g., the S-EES  100  may receive the N6 routing information when receiving a message from the T-EES  200  in operation S 707 ). Operation S 70 E6 of transmitting the AF request message may be performed in operation S 712  after application context relocation is completed. 
     In operation S 708 , the S-EES  100  may transmit a context relocation response message to the S-ESA  101 . 
     In operation S 709 , the S-EAS  101  may transmit application context to the T-EAS  201  upon receiving the context relocation response message. In operation S 710 , the S-EAS  101  may transmit an application context transfer complete notification message to the S-EES  100 . 
     In operation S 711 , the S-EES  100  may transmit the complete notification message of operation S 710  to the UE  300 . 
     The N6 routing information included in the AF request message is routing information corresponding to the T-EES  200  or the T-EAS  201  to which the UE  300  needs to be newly connected to receive a service, and needs to be transmitted to the 3GPP network function (NEF, PCF, or SMF) through the EES or EAS serving as an AF until a new UPF is activated after the application context relocation is completed. In addition to the operations illustrated above in the embodiment, an operation of transmitting the N6 routing information from the T-EES  200  to the S-EES  100  is also included in the disclosure. Further, instead of the S-EES  100 , the T-EES  200  or the T-EAS  201  may perform an AR request operation (AF request to influence traffic routing) to directly transmit the N6 routing information to the 3GPP network function. 
       FIG.  8    illustrates a signal flowchart for providing continuity of an edge computing service based on movement of a UE according to various embodiments of the disclosure. 
     The aforementioned embodiments of  FIG.  8    illustrates a method in which an EAS provides a timer value for UP path management to an EES and a 3GPP network  400  while transmitting a UP path management event API request message. 
     In operation S 801 , an EAS  101  may transmit a user plane path management event API request to an EES  100  and may also provide a suggested (preferred) timer value for UP path management (e.g., a PSA release timer value or an old IP prefix release timer value) or an estimated time required for application context relocation. Alternatively, the EAS  101  may transmit the request including a UP path management coordination indication to the EES  100  without suggesting a specific timer value. The UP path management coordination indication may include a meaning of requesting an SMF (e.g.,  441  in  FIG.  3   ) of the 3GPP network  400  to use a PSA release timer value or an old prefix release timer value that is greater than a normal value (may request use of a great value among values in a local configuration in the SMF). 
     In operation S 802 , the EES  100  may store the provided timer value and may transmit a subscription request to a UP path management event notification service using an API provided by the 3GPP network, thus providing the timer value provided from the EAS  101 . When no timer value is provided from the EAS  101 , the EES  100  may determine a timer value based on the local configuration and may transmit the timer value. The SMF  441  of the 3GPP network provided with the timer value may use the timer value received from the EES  100  to configure an old PSA release timer, a PDU session address lifetime, an old IP prefix release timer, or the like when performing UP path management. When receiving the UP path management coordination indication, the EES  100  may transmit the indication to the SMF  441 , and the 3GPP network  400  or a function device (e.g., the SMF) may receive the indication and may then configure the PSA release timer value or the old IP prefix release timer value to be greater than the normally used value. 
     When failing to receive the suggested timer value for UP path management or the UP path management coordination indication from the EAS  101 , the EES  100  may configure a suggested timer value, a UP path management coordination indication, or an indication of AF acknowledgment to be expected according to an EAS profile or a local configuration stored in the EES  100  and may transmit the same to the 3GPP network  400 . When these parameters are included in an AF request message, a function device (e.g., an NEF, a PCF, or the SMF) of the 3GPP network  400  may perform an early notification or a late notification and may adjust the configured value of a PSA release timer or an old IP prefix release timer (e.g., use the received suggested timer value or configure the timer using a value greater than the normal configured value) to achieve runtime coordination with an AF. 
     In operation S 803 , the EES  100  may transmit a user plane path management event API subscribe/unsubscribe response to the EAS  101 . 
     Although the disclosure illustrates an example in which the EEC  52  is configured separately from the modem, the same operations in various configuration methods are also included in suggestions of the disclosure without departing from the scope of the disclosure. For example, the operations described in the embodiments of the disclosure may also be applied to an EEC  52  being configured in a modem  51  and interworking with a lower layer within the modem. In addition, although the disclosure illustrates an embodiment of separately configuring the communication processor in which the modem  51  is configured and the application processor in which the upper layer is configured as an example, the same operations suggested in the disclosure may be applied when the communication processor and the application processor are configured together in the same processor chip. 
       FIG.  9    illustrates a functional block diagram of a network function, an EAS, or an EES according to various embodiments of the disclosure. 
     Referring to  FIG.  9   , the network function, the EAS, or the EES may include a communication circuit  901 , a processor  902 , and a memory  903 . Each of the network function, the EAS, or the EES may include an additional component and may be configured to run in the form of software in a specific server. When running in the form of software, the network function, the EAS, or the EES may be configured in a separate slice form. 
     The communication circuit  901  may perform conversion and encoding/decoding in accordance with a protocol in order to communicate with a different node in a network. 
     The processor  902  may be configured as at least one processor and may perform an operation according to each network function. 
     The memory  903  may store pieces of information required for each network function and may temporarily or semi-statically store the messages described above. 
     Although specific embodiments have been described in the detailed description of the disclosure, various modifications are possible without departing from the scope of the disclosure. Therefore, the scope of the disclosure should not be limited to the described embodiments and should be defined not only by the claims described below but also by the claims and equivalents thereof. 
     Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.