Method and apparatus for controlling network congestion in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for providing a higher data transmission rate than a previous 4G communication system, such as LTE. A method performed by a user plane function (UPF) entity in a wireless communication system according to the present disclosure may comprise the steps of: receiving, from a session management function (SMF) entity, N4 session information including an explicit congestion notification (ECN) activation indicator and an ECN tuning parameter; identifying a QoS flow to which activation of an ECN-related function is to be applied on the basis of the ECN activation indicator; and performing data communication on the basis of the ECN activation indicator and the ECN tuning parameter. Various other embodiments identified through the specification are possible.

Description

Method and device for controlling network congestion in wireless communication system The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for controlling network congestion in a wireless communication system. Looking back at the development process over the generations of wireless communication, technologies have been developed primarily for human-targeted services such as voice, multimedia, and data. After the commercialization of the 5G (5th Generation) communication system, it is expected that connected devices, which are increasing explosively, will be connected to the communication network. Examples of objects connected to the network include vehicles, robots, drones, home appliances, displays, smart sensors installed in various infrastructures, construction equipment, and factory equipment. Mobile devices are expected to evolve into various form factors such as augmented reality glasses, virtual reality headsets, and holographic devices. In the 6G (6th Generation) era, efforts are being made to develop an improved 6G communication system in order to connect hundreds of billions of devices and objects and provide various services. For this reason, the 6G communication system is called a system beyond 5G. The maximum transmission speed in the 6G communication system, which is expected to be realized around 2030, is tera (i.e., 1,000 giga) bps (bits per second), and the wireless delay time is 100 microseconds (μsec). In other words, the transmission speed in the 6G communication system is 50 times faster than that of the 5G communication system, and the wireless delay time is reduced to one-tenth. To achieve such high data rates and ultra-low latency, 6G communication systems are being considered for implementation in the terahertz (THz) band (e.g., from 95 gigahertz (GHz) to 3 terahertz (THz) band). Compared to the millimeter wave (mmWave) band introduced in 5G, the terahertz band is expected to have more serious path loss and atmospheric absorption phenomena, and thus the importance of technologies that can guarantee signal reach, or coverage, is expected to increase. Key technologies to ensure coverage include RF (Radio Frequency) components, antennas, new waveforms that are better than OFDM (Orthogonal Frequency Division Multiplexing) in terms of coverage, beamforming, and multiple antenna transmission technologies such as massive Multiple-Input and Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and large scale antennas. In addition, new technologies such as metamaterial-based lenses and antennas, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surfaces (RIS) are being discussed to improve the coverage of terahertz band signals. In addition, in order to improve frequency efficiency and system network, 6G communication systems are being developed with full duplex technology that utilizes the same frequency resources at the same time for uplink and downlink, network technology that comprehensively utilizes satellites and HAPS (High-Altitude Platform Stations), network structure innovation technology that supports mobile base stations and enables optimization and automation of network operation, dynamic spectrum sharing technology through collision avoidance based on spectrum usage prediction, AI-based communication technology that utilizes AI (Artificial Intelligence) from the design stage and internalizes end-to-end AI support functions to realize system optimization, and next-generation distributed computing technology that realizes services with complexity that exceeds the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources (Mobile Edge Computing (MEC), cloud, etc.). In addition, efforts are being made to further strengthen connectivity between devices, further optimize networks, promote softwareization of network entities, and increase the openness of wireless communications by designing new protocols to be used in 6G communication systems, implementing hardware-based security environments, developing mechanisms for safe use of data, and developing technologies for maintaining privacy. These research and developments in 6G communication systems are expected to enable the next hyper-connected experience through the hyper-connectivity of 6G communication systems that include not only connections between things but also connections between people and things. Specifically, 6G communication systems are expected to enable the provision of services such as truly immersive eXtended Reality (XR), high-fidelity mobile holograms, and digital replicas. In addition, services such as remote surgery, industrial automation, and emergency response through enhanced security and reliability will be provided through 6G communication systems, which will be applied in various fields such as industry, medicine, automobiles, and home appliances. Various embodiments disclosed in this document provide methods and devices for controlling network congestion situations that may occur within a wireless communication system network. According to various embodiments disclosed in the present document, a method performed by a user plane function (UPF) entity in a wireless communication system may include the steps of receiving, from a session management function (SMF) entity, N4 session information including an explicit congestion notification (ECN) activation indicator and an ECN tuning parameter, identifying a QoS flow to which activation of an ECN related function is to be applied based on the ECN activation indicator, and performing data communication based on the ECN activation indicator and the ECN tuning parameter. According to various embodiments disclosed in the present document, a method performed by a user equipment in a wireless communication system includes the steps of transmitting, to a session management function (SMF) entity via a base station, a PDU session establishment request message including ECN information supportable in a PDU session connection, receiving, from the SMF entity via the base station, a PDU session establishment response message including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter, and performing data communication based on the PDU session establishment response message, wherein the PDU session establishment response message may include information identifying a QoS flow to which the base station applies activation of an ECN related function based on the ECN activation indicator. According to various embodiments disclosed in the present document, in a wireless communication system, a user plane function (UPF) entity may include at least one transceiver and a controller coupled with the at least one transceiver. The controller may be configured to receive N4 session information including an explicit congestion notification (ECN) activation indicator and an ECN tuning parameter from a session management function (SMF) entity, identify a QoS flow to which activation of an ECN related function is to be applied based on the ECN activation indicator, and perform data communication based on the ECN activation indicator and the ECN tuning parameter. According to various embodiments disclosed in the present document, a user equipment in a wireless communication system may include at least one transceiver and a controller coupled with the at least one transceiver. The controller may transmit, to a session management function (SMF) entity via a base station, a PDU session establishment request message including ECN information supportable in a PDU session connection, and receive, from the SMF entity via the base station, a PDU session establishment response message including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter, and is configured to perform data communication based on the PDU session establishment response message, wherein the PDU session establishment response message may include information identifying a QoS flow to which the base station applies activation of an ECN related function based on the ECN activation indicator. FIG. 1 illustrates an environment for deploying a 5G network on a cloud according to one embodiment of the present disclosure. FIG. 2 illustrates the relationship between a 5G network and a virtual network according to one embodiment of the present disclosure. FIG. 3 illustrates an operation of controlling congestion by utilizing ECN (explicit congestion notification) of TCP (transport control protocol) in a wireless communication system according to one embodiment of the present disclosure. FIG. 4 illustrates the structure of a user plane packet header of a 5G network operating on a cloud according to one embodiment of the present disclosure. FIG. 5 illustrates an operation of activating an ECN function according to one embodiment of the present disclosure. FIG. 6 illustrates an operation of performing downlink transmission according to one embodiment of the present disclosure. FIG. 7 illustrates an operation of performing uplink transmission according to one embodiment of the present disclosure. FIG. 8 illustrates an operation of performing congestion control using a transmission control rule according to one embodiment of the present disclosure. FIG. 9 illustrates the operation of a user plane function (UPF) entity according to one embodiment of the present disclosure. FIG. 10 illustrates the operation of a terminal according to one embodiment of the present disclosure. FIG. 11 illustrates the structure of a core network entity according to one embodiment of the present disclosure. FIG. 12 illustrates the structure of a base station according to one embodiment of the present disclosure. FIG. 13 illustrates the structure of a terminal according to one embodiment of the present disclosure. In connection with the description of the drawings, the same or similar reference numerals may be used for identical or similar components. Various aspects of the claimed subject matter are described with reference to the drawings, wherein like reference numerals are used to refer to like elements. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that the embodiment(s) may be practiced without these specific details. The terms used in this disclosure are only used to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include the plural expression unless the context clearly indicates otherwise. The terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by a person having ordinary skill in the art described in this disclosure. Among the terms used in this disclosure, terms defined in general dictionaries may be interpreted as having the same or similar meaning as the meaning they have in the context of the related technology, and shall not be interpreted in an ideal or excessively formal meaning unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure. In the following description, terms referring to signals (e.g., message, signal, signaling, sequence, stream), terms referring to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), Occasion), terms for operations (e.g., step, method, process, procedure), terms referring to data (e.g., information, parameter, variable, value, bit, symbol, codeword), terms referring to channels, terms referring to control information (e.g., downlink control information (DCI), medium access control element (MAC CE), radio resource control (RRC) signaling), terms referring to network entities, terms referring to device components, etc. are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. Various embodiments of the present disclosure are described herein in connection with a wireless terminal and / or a base station. A wireless terminal may refer to a device that provides voice and / or data connectivity to a user. A wireless terminal may be connected to a computing device, such as a laptop computer or a desktop computer, or may be a self-contained device, such as a personal digital assistant (PDA). A wireless terminal may also be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile, a mobile device, a remote station, a remote terminal, an access terminal, a user terminal, a terminal, a wireless communication device, a user agent, a user device, or a user equipment. A wireless terminal may be a subscriber station, a wireless device, a cellular telephone, a PCS telephone, a cordless telephone, a Session Initiation Protocol (SIP) telephone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless connectivity capabilities, or other processing device connected to a wireless modem. A base station (e.g., an access point) may refer to a device within an access network that communicates with wireless terminals over a wireless interface through one or more sectors. The base station may comprise an Internet Protocol (IP) network by converting received air interface frames into IP packets and may act as a router between the wireless terminals and the rest of the access network. The base station may also coordinate management of properties for the air interface. With the introduction of 5G communication technology, mobile communication networks have been developed based on the softwareization / virtualization of network functions. Existing network functions were developed / distributed in a closed form consisting of dedicated hardware and software, but with the introduction of 5G communication technology, hardware and software were separated, and network functions for providing actual mobile communication network services have evolved into a form that operates on the cloud in the form of software. One of the major characteristics of the cloud environment is that software is executed in a virtualized environment. This virtualization includes virtualization of computing resources for computing, and the network is also provided in a virtualized form. This virtualization refers to technologies for dividing physical resources and providing each user with the same function or performance as the actual physical resources. In addition, the network also provides a virtual network function so that each user can have the same function as if they own a dedicated network resource. This virtual network includes methods for isolating each virtual network in a cloud or a physical network environment shared by multiple users. These methods specifically use a method of inserting an additional header into packets generated in the virtual network to distinguish them from packets in other networks. This virtualized environment has the advantage of enabling the use of divided physical resources, but problems may arise when using functions that should be provided by non-virtualized devices or networks. Hereinafter, various embodiments disclosed in this document are intended for cases where a network function (NF) for providing 5G, particularly a user plane function (UPF) entity for transmitting user data packets, is deployed in a virtualized environment. The UPF entity may be connected to a base station (RAN) and may perform a role of transmitting user packets between the outside and a terminal. The UPF entity and the base station may generally be connected using a GTP-U (GPRS (general packet radio service) tunneling protocol-user plane) tunnel. Packets between the UPF entity and the base station operated on a virtualized network may additionally include header information for the virtualized network and GTP-U header information for operating the 5G network. In this case, in order for the functions provided to the virtual network device to perform a role in an actual user service, the information must be transmitted or the header must be changed in consideration of the modified header of the virtual network or mobile communication network. For example, as a representative example, an explicit congestion notification (ECN) marking function may be utilized as a function for the network device to support control of congestion of the user service flow. ECN marking can represent a series of operations that indicate whether there is congestion in the ECN field of the IP header of the transmitted and received data packet. In order for a network device in a virtualized network to indicate whether there is congestion while transmitting and receiving uplink data or downlink data, the ECN marking should be included in the IP header located at the innermost part so that it can be transmitted to a user terminal or an external server. Therefore, a method is required to ensure that the function provided by the virtualized network device or the mobile communication network device is transmitted inside the actual data packet. Below, this paper proposes a method to effectively perform flow control and congestion control of the transport layer in a virtualized mobile communication network. 'Virtualization' refers to the abstraction of hardware resources (e.g., computing resources, memory resources, network resources). By virtualization, hardware resources of network devices (e.g., general-purpose server devices) are abstracted and / or shared, and some of the entire hardware resources are used to perform specific network functions. For example, multiple network functions can be performed on a single network device by virtualization. The terms referring to network entities, terms referring to components of a device, etc. used in the following description are examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. For reference, the transport network devices referred to in this document may refer to devices operating on the path between the UPF and the RAN operating in the cloud. For example, virtual switches, virtual routers, physical switches, or physical routers may be considered transport network devices. The names described in this document are borrowed from the network entities used in the 5G communication system and the terms used in the 5G communication system. For example, the 5G communication system described in this document may have a UPF entity that processes data packets and an SMF (session management function) entity that controls rules related to the processing of data packets. In addition, for example, the 5G communication system described in this document may have entities that affect the selection of SMF entities and UPF entities, such as an NRF (network repository function) and an SCP (service communication proxy) to support the discovery of NFs. In addition, there may be a data session manager that performs control related to commands issued from an SMF entity to a UPF entity, and the data session manager in this case may be implemented as a part of the SMF entity or as an internal function of the SMF entity. Below, each network function described in this document is described by borrowing from a 5G communication system, and entities with similar functions can be operated by configuring a communication system according to an embodiment of the present invention in a post-5G or 6G mobile communication network. FIG. 1 illustrates an environment for deploying a 5G network on a cloud according to one embodiment of the present disclosure. Specifically, FIG. 1 illustrates an example of providing a network system for 5G mobile communications in a cloud or virtualized environment. Referring to FIG. 1, the NFV environment, which represents an environment in which a network function is performed in virtualized network equipment, may include virtualized physical resources (e.g., virtual compute, virtual storage, and virtual network) and hardware resources (e.g., physical compute, physical storage, and physical network) to provide applications, applications, or network functions (NF) operating within a virtual machine (VM) or container. A virtualized cloud platform can provide an environment in which applications can operate smoothly by supplying and connecting virtualized resources to actual virtual machines or containers. Representative cloud platforms include, for example, Redhat openshift, OCP (open compute project), and windrive. In addition, an Orchestrator or manager that is responsible for managing the entire virtualized network environment, deploying / managing applications, and managing virtual resources may exist in the NFV environment. FIG. 2 illustrates a relationship between a 5G network and a virtual network according to one embodiment of the present disclosure. Specifically, FIG. 2 illustrates a UPF entity operating in a 5G network and a next generation radio access network (NG-RAN) operating on a virtual network. Connections between network entities operating within the cloud are made through virtual networks (or overlay networks), and these virtual networks may differ from the forms recognized by actual 5G network (or underlay network) entities. For example, the configuration of a cloud node or network device providing actual resources to an actual 5G network and an application or device on which an application is used may differ from each other. Referring to (A) of FIG. 2, the UPF entity and the NG-RAN may be connected to the N3 interface, which is a link through which tunneled GTP-U packets are transmitted. The entities utilizing each N3 interface may be abstracted so that the NG-RAN and UPF entities recognize the N3 interface as a single link. However, although the N3 interface between the NG-RAN and the UPF is a single link from the perspective of the 5G user plane, from the cloud perspective, actual packets may be transmitted through a path of a virtual network embedded through multiple physical links or devices. Figure 2 (B) illustrates a case where NG-RAN and UPF are operated on different clouds or only one of them is operated on the cloud. Specifically, it illustrates a case where only a part corresponding to a core network of a mobile communication system is operated on the cloud, and the NG-RAN corresponding to a base station is operated in a different location. In this case, a cloud gateway that connects a public network and a cloud network can additionally perform operations such as deleting packet headers for a virtual network so that packets of a 5G network can operate normally on the public network. Meanwhile, in order to provide a virtual network, header information may be added to facilitate processing of virtual network packets by utilizing protocols such as VLAN (virtual local area network) and VxLAN (virtual extensible local area network). When header information is added to facilitate processing of virtual network packets, the physical network can process packets by referring only to the outermost packet header information. This will be described in detail in FIG. 4 below. FIG. 3 illustrates an operation of controlling congestion by utilizing ECN (explicit congestion notification) of TCP (transport control protocol) in a wireless communication system according to one embodiment of the present disclosure. TCP is a representative protocol that provides functions of transmission control and congestion control at the transport layer on the network. TCP is usually used with the IP (internet protocol) protocol located at the network layer. TCP provides various functions in addition to transmission control (flow control) and congestion control, and there are many versions of the algorithms that it actually provides. In a network connection based on TCP, network devices can provide information related to congestion. When transmitting data packets using a TCP connection, the network can indicate that the data packet has experienced congestion in the ECN (explicit congestion notification) field in the IP header of the data, considering internal queues, buffers, resource status, etc. Data packets that have been indicated to have experienced congestion can be transmitted from the sender side to the receiver side through a network device, and the receiver side can perform actions according to the congestion situation. If the value of bit 2 of the ECN field is 00, it may mean that the ECN function is not used. If the value of bit 2 of the ECN field is 10 or 01, the ECT (ECN capable transport) flag may be set, meaning that ECN is supported, but the current network load level of packets being transmitted and received is normal. If the value of bit 2 of the ECN field is 11, the CE (congestion experienced) flag may be set, meaning that ECN is supported, but the network load is not normal and it may be difficult to maintain the current bitrate. Referring to FIG. 3, the operation of a transmitter, a receiver, and a network device (e.g., a switch or a router) between the transmitter and receiver in a TCP-based network connection is illustrated. In operation 310, the transmitter and receiver can establish a TCP connection using TCP and transmit data packets. If the transmitter and receiver can utilize the ECN function in the TCP connection, the transmitter can mark the ECN field in the IP header of the data packet transmitted to the receiver. For example, the transmitter of FIG. 3 can mark the bit value of the ECN field located in the IP header of the data packet transmitted to the receiver as 01 or 10. The ECN field marked as 01 or 10 can indicate that the ECT flag is set. In operation 320, a network device such as a switch or a router located on a path for transmitting data packets between a transmitter and a receiver may predict that the network device will be in a congestion situation based on its own judgment. The network device may read an IP header or a TCP header, and if a congestion situation is predicted for network communication, the network device may set a CE (congestion experienced) flag by marking an ECN field located in an IP header within a data packet as 11. Accordingly, the network device may notify the receiver of the congestion situation by transmitting a data packet including the marked ECN field. In operation 330, a receiving end that receives a packet including an ECN field marked with 11 corresponding to a CE flag from a network device can set an ECE (ECN-Echo) flag in the TCP header of an uplink packet (e.g., TCP ACK) corresponding to the packet and transmit it to the transmitting end. Through this, the receiving end can transmit feedback notifying the transmitting end that congestion has occurred. In operation 340, the transmitter side, which has received feedback from the receiver side, may recognize that congestion has occurred and perform a control operation according to the congestion situation. For example, the transmitter side, which has received feedback including an ECE flag in the TCP header from the receiver side, may reduce the size of the congestion window to lower the data transmission rate. In operation 350, the transmitter may transmit a response message to the receiver including information that it has performed an operation for controlling congestion, such as reducing the size of a congestion window, according to an ECE field. For example, the transmitter may transmit information that it has reduced the size of a congestion window by setting a CWR (congestion window reduced) flag in the TCP header of data to the receiver. The receiving side can know that the congestion control operation of the sending side has been performed by receiving a packet with the CWR flag set in the TCP header. These transmitters, receivers, and network devices can control congestion situations occurring within a network using TCP. However, the algorithms and field meanings used in the process of controlling congestion situations in a network using TCP may differ depending on the version of TCP used. FIG. 4 illustrates the structure of a user plane packet header of a 5G network operating on a cloud according to one embodiment of the present disclosure. The user plane packet header transmitted over the virtual network may include additional header information to ensure smooth transmission over the virtual network. For example, a VLAN (virtual local access network) field that extends the Ethernet header may be utilized as the additional header information. In addition, VxLAN (virtual extension LAN) may be utilized as the additional header information to remove the maximum number of virtual networks that a VLAN can provide by adding a packet header corresponding to layer 3 and to provide additional information. In one example, when a 5G network is implemented on a cloud, packet headers transmitted from an N9 interface connecting a UPF entity to another UPF entity and an N3 interface connecting a UPF entity to a RAN may additionally include a VLAN header for supporting virtual networks and a GTP-U header for tunneling in a mobile communication network. FIG. 4 shows a header structure of a user plane packet that can be measured on a link of a mobile communication network operating on a virtual network. Referring to FIG. 4, a user plane packet used in a virtual network can be composed of an outer header part (410) processed in the virtual network, a GTP-U header part (420) processed in an N3 interface between a UPF entity and a base station, and an actual application packet part (430) actually used between a transmitter and a receiver (e.g., a server and a terminal). As described above, in addition to the payload including the header and data of the packet actually transmitted, a GTP-U header and a VXLAN header may be added while passing through a network device. At this time, a virtual network device that processes the packet can process the packet using the outer header including the VXLAN located on the outer side. In addition, packets transmitted and received to and from cloud applications such as UPF entities or RANs can be processed using the IP header including the GTP-U with the virtual header removed. Therefore, in packet transmission between the transmitter and receiver that actually transmit and receive packets, even if the ECN field is marked in the IP header in a network device (e.g., a switch or a router) that supports a virtualized network or a device that supports GTP-U, there may be a problem that the packet is not transmitted to the transmitter and receiver. In addition, a network device that supports a virtualized network or a device that supports GTP-U cannot determine whether to set the IP header of the VXLAN or GTP-U header to have the ECN field marked. Below, FIGS. 5 to 10 propose a method for controlling congestion by marking an ECN field in an IP header in a network device (e.g., a switch or a router) supporting a virtualized network or a device supporting GTP-U, and allowing the marked ECN field to be transmitted to the transmitter and receiver. FIG. 5 illustrates an operation for activating an ECN function according to an embodiment of the present disclosure. Specifically, FIG. 5 illustrates a procedure for activating an ECN function in order to control a congestion situation by interacting with a 5G core network entity, a terminal, and a base station. The ECN function may be a term that collectively refers to marking an ECN field in a packet header or a function required for marking an ECN field. In operation 510, the terminal may transmit a PDU session establishment request message to the SMF entity to establish a new PDU session. For example, the terminal may transmit the PDU session establishment request message to the SMF entity through the connected base station and the AMF (access and mobility management function) entity. The transmission procedure of the PDU session establishment request message may follow the message transmission procedure and method in the control plane of the 5G core network. However, the present invention is not limited thereto. According to one embodiment of the present disclosure, ECN capability information may be included in a PDU session establishment request message. The ECN capability may include ECN information that can be supported for a terminal or service in a PDU session connection. In one example, the ECN capability information may specifically include information such as whether an ECN function is supported in a PDU session connection, a TCP version, whether transmission based on RTT (round trip time) can be controlled, and a transmission or congestion control algorithm that can be supported. However, the information included in the ECN capability is not limited thereto, and information related to ECN may be included in addition to the information mentioned above. Meanwhile, the PDU session establishment request message may generally include information such as a DNN (data network name) and S-NSSAI (single network slice selection assistance information) that are included when transmitting a PDU session establishment request message, and may also include other information for establishing a PDU session. In operation 520, the SMF entity may perform an operation to determine a PDU session to be established based on a PDU session establishment request message received from the terminal. For example, the SMF entity may perform operations such as searching for data to be subscribed to, authenticating a PDU session to be established, selecting a PCF (policy control function) entity, and establishing an SM policy. According to one embodiment of the present disclosure, an SMF entity can determine whether a terminal has the authority to activate an ECN-related function through ECN capability information included in a PDU session establishment request message. However, in one example, even if the SMF entity does not explicitly receive ECN capability information through the PDU session establishment request message, it can also obtain whether a terminal or user has the authority to activate an ECN-related function and a request of the terminal or user related to the ECN function based on local data. At operation 530, the SMF entity may select a UPF entity and a path to establish a PDU session requested from the terminal. In one example, the SMF entity may select a UPF entity and a path supporting the ECN function based on the information received from the terminal at operation 510. The SMF entity may acquire candidate UPF entities according to an NRF or local policy, and may select an NF profile that can support the ECN function among NF profiles of each of the candidate UPF entities. At this time, the SMF entity may select a UPF entity matching the selected NF profile as the UPF entity used to establish the PDU session. At operation 540, the SMF entity can establish an N4 session to transmit information related to actual packet processing to the UPF entity selected at operation 530. The SMF entity can transmit rules, such as a packet detection rule (PDR), a forwarding action rule (FAR), and a QoS enforcement rule (QER), to the UPF entity as N4 session information to identify and manage QoS flows to be processed in the newly established PDU session. According to one embodiment of the present disclosure, an SMF entity may transmit to a UPF entity factors related to activation of an ECN function by including them in N4 session information. The factors related to activation of the ECN function may include a first ECN indicator for causing the UPF entity to process an ECN field and second ECN indicators for causing a network device to process the ECN field. The first ECN indicator may also be referred to as a 5G ECN indicator, and the second ECN indicator may also be referred to as a TN ECN indicator. However, the present invention is not limited thereto. Factors related to activation of the ECN function may be transmitted from the SMF entity to the UPF entity by adding a new field to existing PDR, FAR, QER, etc. However, a method of transmitting factors related to activation of the ECN function is not limited thereto, and may be transmitted separately. The first ECN indicator may instruct the UPF entity and the RAN to set the CE flag by marking 11 in the ECN field in the user packet header depending on the resource status to indicate a congestion situation. For example, if the current link utilization of the UPF entity exceeds a certain threshold, the UPF entity may set the CE flag by marking 11 in the ECN field in the header of the user packet. In one example, when the ECN field is utilized for not only congestion control but also L4S (low latency, low loss, and scalable throughput), the first ECN indicator may instruct to change the ECT flag setting to prevent an incorrect operation from being performed. For example, when the ECN field is marked with 01 to indicate L4S traffic for L4S, a collision may occur depending on whether there is L4S traffic, so it may be instructed to modify the ECT flag of the ECN field to 10 to avoid the collision. The operation to prevent the collision when the ECN field is used for L4S traffic and congestion control may be performed at a step in which a UPF entity receives a packet from a server through a link of an N6 interface, or at a step in which a RAN receives a packet from a terminal and transfers it to the UPF entity through an N3 interface. The second ECN indicator can instruct operations related to the ECN function in a transport network (TN) where the UPF processes a QoS flow or a PDU session. In one example, in order to utilize ECN in a transport network, it may need to be processed in the process of generating an additional packet header, such as VXLAN, so that a packet passes through a virtual network. The second ECN indicator can set ECT so that a UPF entity can utilize an ECN field of a packet header in the process of transmitting and receiving packets, and can instruct to copy the CE to the IP header of a user packet located at the innermost position when a CE is set in the outermost header in the process of decapsulating packets for a virtual network. In addition, the second ECN indicator can be used when a network device of a virtual network performs ECN marking on packets transmitted and received between a UPF entity and a base station. In one example, an SMF entity can transmit an ECN tuning parameter to a UPF entity by adding it to N4 session information. The ECN tuning parameter can include information on a condition for the UPF entity, RAN, and a transmission network device between the UPF entity and the RAN to perform ECN marking. For example, the ECN tuning parameter can include information on a condition for marking CE with a 30% probability when a buffer capable of accommodating packets of the UPF entity is 50% or more, or for marking CE with a 100% probability when a buffer capable of accommodating packets of the UPF entity is 80% or more. The ECN tuning parameter transmitted to the UPF entity can specifically include combinations of monitoring factors for a buffer capable of accommodating packets of the UPF or RAN, thresholds, and ECN marking probabilities according to the thresholds. In operation 545, the UPF entity can receive N4 session information including information such as a first ECN indicator, a second ECN indicator, and ECN tuning parameters from an SMF entity. The UPF entity can activate functions related to ECN so that the QoS flow associated with the received information can utilize the ECN field. In operation 550, if the PDU session is successfully established, the SMF entity may transmit a PDU session establishment success message to the terminal. In one example, the SMF entity may include factors related to the activation of the ECN function in the PDU session establishment success message and transmit it to the base station. Alternatively, the SMF entity may transmit N2 session information to the base station via the AMF entity, including factors related to the activation of the ECN function. Factors related to activation of the ECN function may include a first ECN indicator for causing the base station to process the ECN field and second ECN indicators for causing the network device to process the ECN field. The first ECN indicator and the second ECN indicator are identical to the first ECN indicator and the second ECN indicator that the SMF entity transmits to the UPF entity in operation 540, and therefore, a detailed description thereof will be omitted. In one example, an SMF entity can transmit an ECN tuning parameter in a PDU session establishment success message or N2 information. The ECN tuning parameter transmitted to the RAN may specifically include a combination of a monitoring factor for the RAN's buffer that comprehensively considers the size of the buffer, the strength of the received signal, and the mobility of the user, a threshold value, and an ECN marking probability according to the threshold value. Since the RAN can additionally consider information about radio resources compared to the UPF entity, information included in the ECN tuning parameter transmitted from the SMF entity to the UPF entity may be different from information included in the ECN tuning parameter transmitted from the SMF entity to the RAN. That is, factors to be monitored to determine whether an ECN condition is satisfied may be different between the UPF entity and the RAN. In operation 555, the RAN may receive information such as a first ECN indicator, a second ECN indicator, and an ECN tuning parameter through a PDU session establishment success message or N2 session information. The RAN may activate a function related to ECN so that a QoS flow associated with the received information may utilize the ECN field. For example, the RAN may perform ECN marking for a QoS rule based on the received first ECN indicator. In addition, the RAN entity may perform an operation of requesting ECN marking in an ECN field in a header of a packet transmitted and received from a device of a transport network based on the received second ECN indicator. Based on the above-described operation, the UPF entity and the base station can activate the ECN function in the virtualized network environment. Thereafter, the UPF entity and the base station can mark the ECN field in the packet according to the congestion status based on the activated ECN function while performing communication of uplink or downlink data. Hereinafter, the specific details will be described with reference to FIGS. 6 and 7. FIG. 6 illustrates an operation of performing downlink transmission according to one embodiment of the present disclosure. Referring to FIG. 6, in operation 605, a terminal, a server, a RAN (or base station) of a 5G network, a UPF, and a network device (e.g., a switch or a router) used in a virtualized network may activate an ECN-related function so as to perform ECN marking on an ECN field of a header in a transmitted and received packet. The process of each device activating the ECN-related function in operation 605 may follow the procedure of activating the ECN function in FIG. 5. At operation 610, the server may transmit downlink (DL) data to the UPF via the N6 interface. In one example, the downlink data may mark the ECN field as 01 or 10. An ECN field marked as 01 or 10 may indicate that the ECT flag is set. The server may transmit downlink data with the ECT flag set to the UPF entity. In operation 615, the UPF entity that receives the packet through the N6 interface may perform its own ECN function related algorithm and mark the ECN field in the IP header of the packet as 11 based on the result to set the CE flag. At this time, the criterion for performing ECN marking on the IP header of the packet of downlink data by the UPF entity may be based on the ECN tuning parameter received by the UPF entity from the SMF entity. For example, the UPF entity may perform ECN marking based on the ECN tuning parameter received in operation 540 of FIG. 5. In one example, when a feature using ECN fields such as L4S is enabled in a mobile communication network, the UPF entity may set the ECT flag to a field value other than the field value set by L4S among 01 or 10 to avoid collision with the ECN field marked in the IP header of the packet of downlink data. In one example, a packet of downlink data transmitted by a UPF entity to a base station may have an additional external header, such as VXLAN, attached to it so that a virtual network device or a network interface device of a virtual machine or virtual container running the UPF entity can transmit the packet to the base station in a virtual network. In one example, if the second ECN indicator received from the SMF entity in operation 605 is true, the UPF entity may perform ECN marking with 01 or 10 as an ECT flag on an IP header of the additionally attached VXLAN header. In operation 620, the UPF entity can encapsulate downlink data to transmit the downlink data to the base station through a virtual network. The virtual network can be abstracted as an N3 interface utilizing a GTP-U tunnel in a mobile communication network. In operation 625, a virtual network device located between a UPF entity and a base station may perform ECN marking on a packet if the packet of received downlink data satisfies an ECN-related condition using its own algorithm. For example, a virtual network device such as a virtual switch or a virtual router located between a UPF entity and a base station may perform ECN marking of CE (11) on an outer header of the packet if the IP header of the packet of data received from the UPF entity is ECN-marked with ECT (01) or ECT (10) using its own algorithm. Here, the outer header may indicate a header that is outer than an actual application packet (e.g., FIG. 430) or a GTP-U header (e.g., FIG. 420). For example, the outer header may indicate an outer header (410) for a virtual network of FIG. 4. At operation 630, the virtual network device can forward downlink data encapsulated by the UPF entity to the base station. In operation 635, the base station can receive downlink data encapsulated by a UPF entity from a virtual network. The base station can remove a packet header, such as VXLAN, added by the UPF entity to transmit data to the base station through the virtual network. The downlink data received by the base station may have the ECN field of the outer header marked as CE(11) by the device of the virtual network. In one example, if the base station receives a second ECN indicator from the SMF entity in operation 605 (in particular, for example, operation 550 of FIG. 5), the base station may copy the ECN field value of the outer header of the packet of the downlink data marked as CE(11) to the IP header of the GTP-U header if the second ECN indicator is true. Meanwhile, this copying operation of the base station may be performed while the base station removes a packet header, such as VXLAN, added to the packet of the encapsulated downlink data. In one example, the base station may perform an operation to remove the GTP-U header from a packet from which an outer header such as VXLAN has been removed, according to its own algorithm, and transmit the packet to the terminal through the radio interface. In one example, the base station may perform ECN marking with CE (11) on the inner header of the packet to be transmitted to the terminal based on its own algorithm or an ECN tuning parameter received from an SMF entity through an AMF entity in operation 605. Here, the inner header may indicate a header part corresponding to an actual application packet (e.g., 430 of FIG. 4). In operation 640, the base station may transmit downlink data to the terminal. In one example, the downlink data transmitted by the base station to the terminal may be a packet with an ECN marking of CE (11) in the inner header. In operation 645, a terminal that has received downlink data from a base station can check an ECN field marked in an inner header within a packet of the downlink data. In one example, the terminal can control a congestion situation according to the checked ECN field value. For example, a terminal that has checked an ECN field marked as CE (11) in an inner header can perform an operation for controlling a congestion situation, such as reducing the size of a congestion window. In this way, when congestion is expected depending on the network situation, the ECN field can be marked on the data transmitted and received between the terminal and the server to explicitly recognize the congestion situation. Through this, the terminal can perform congestion control operations according to the congestion situation and prevent the congestion situation in advance. FIG. 7 illustrates an operation of performing uplink transmission according to one embodiment of the present disclosure. Referring to FIG. 7, in operation 705, a terminal, a server, a RAN (or base station) of a 5G network, a UPF, and a device (e.g., a switch or a router) of a virtualized transport network may activate an ECN-related function so as to perform ECN marking on an ECN field of a header in a transmitted and received packet. The process of each device activating the ECN-related function in operation 605 may follow the procedure of activating the ECN function in FIG. 5. In operation 710, the terminal may transmit uplink (UL) data to the base station. In one example, the uplink data may mark the ECN field as 01 or 10. An ECN field marked as 01 or 10 may indicate that the ECT flag is set. The terminal may transmit downlink data with the ECT flag set to the base station. In operation 715, the base station (or RAN) that receives the packet from the terminal may perform its own ECN function related algorithm and mark the ECN field in the IP header of the packet as 11 based on the result to set the CE flag. At this time, the criterion for the base station to perform ECN marking on the IP header of the packet of uplink data may be based on the ECN tuning parameter received by the base station from the SMF entity. For example, the UPF entity may perform ECN marking based on the ECN tuning parameter received in operation 550 of FIG. 5. In one example, when a function using an ECN field such as L4S is enabled in a mobile communication network, the base station may set the ECT flag to a field value other than the field value set by L4S among 01 or 10 to avoid collision with the ECN field marked in the IP header of the packet of uplink data. In one example, a packet of downlink data transmitted by a base station to a UPF entity may have an additional external header, such as VXLAN, attached to it so that a virtual network device or a network interface device of a virtual machine or virtual container running the UPF entity can transmit the packet to the UPF entity in the virtual network. In one example, the base station may perform ECN marking with ECT(01) or ECT(10) on an IP header of a VXLAN header additionally attached to a packet of uplink data if the second ECN indicator received from the SMF entity in operation 605 is true. In operation 720, the base station may encapsulate uplink data to transmit uplink data to a UPF entity through a virtual network. The virtual network may be abstracted in the mobile network as an N3 interface utilizing a GTP-U tunnel. In operation 725, a virtual network device located between a UPF entity and a base station may perform ECN marking on a packet if the packet of uplink data received satisfies an ECN-related condition using its own algorithm. For example, a virtual network device such as a virtual switch or a virtual router located between a UPF entity and a base station may perform ECN marking on an ECN field of an outer header of the packet as CE (11) using its own algorithm if the IP header of a packet of uplink data received from the base station is ECN-marked as ECT (01) or ECT (10). Here, the outer header may indicate a header that is outer than an actual application packet (e.g., FIG. 430) or a GTP-U header (e.g., FIG. 420). For example, the outer header may indicate an outer header (410) for a virtual network of FIG. 4. At operation 730, the virtual network device may forward uplink data encapsulated by the base station to the UPF entity. At operation 735, the UPF entity may receive uplink data encapsulated by the base station from the virtual network. The UPF entity may remove a packet header, such as VXLAN, added by the base station to transmit data to the UPF entity through the virtual network. The uplink data received by the UPF entity may have the ECN field of the outer header marked as CE(11) by the device of the virtual network. In one example, if the UPF entity receives a second ECN indicator from the SMF entity in operation 605 (in particular, for example, operation 540 of FIG. 5), the UPF entity may copy the ECN field value of the outer header of the packet of the uplink data marked as CE(11) to the IP header of the GTP-U header if the second ECN indicator is true. Meanwhile, this copying operation of the UPF entity may be performed while the UPF entity removes a packet header, such as VXLAN, added to the packet of the encapsulated uplink data. In one example, the UPF entity may perform an operation to remove the GTP-U header from a packet from which an outer header such as VXLAN has been removed, according to its own algorithm, and transmit the packet to a data network (DN) (or a server of the data network) through the N6 interface. In one example, the UPF entity may perform ECN marking with CE (11) on the inner header of a packet to be transmitted to a terminal, based on its own algorithm or an ECN tuning parameter received from an SMF entity in operation 605. Here, the inner header may indicate a header part corresponding to an actual application packet (e.g., 430 of FIG. 4). In operation 740, the UPF entity may transmit uplink data to the data network. In one example, the uplink data transmitted by the UPF entity to the data network may be a packet with an ECN marking of CE (11) in the cabinet header. In operation 745, a server of a data network that has received uplink data from a UPF entity may check an ECN field marked in an inner header within a packet of the uplink data. In one example, the server of the data network may control a congestion situation based on the checked ECN field value. In this way, when congestion is expected depending on the network situation, the ECN field can be marked in the data transmitted and received between the terminal and the server to explicitly recognize the congestion situation. Through this, the server of the data network can perform congestion control operations according to the congestion situation, thereby preventing the congestion situation in advance. FIG. 8 illustrates an operation of performing congestion control using a transmission control rule according to one embodiment of the present disclosure. When a protocol supporting flow control or congestion control, such as TCP or QUIC (quick UDP internet connection), is used, congestion can be efficiently resolved or prevented by detecting congestion in the network or transmitting information notifying of congestion. When performing congestion control using TCP, the size of the TCP congestion control window must first be determined. As a method for determining the size of the TCP congestion control window, the AIMD (addictive increase multiplicative decrease) method, which calculates by adding or decreasing the speed when the data speed exceeds or falls below a threshold, or the method of calculating by utilizing the minimum round trip time (RTT_min) and bandwidth information by utilizing the RTT (round trip time), can be utilized. Network operators can drop packets, set the ECN field in packets of data being transmitted or received, or intentionally delay packets to address situations of increased traffic, resource exhaustion, or congestion. According to one embodiment of the present disclosure, in addition to data processing rules such as packet detection rule (PDR), forwarding action rule (FAR), and QoS enforcement rule (QER), a flow control rule (FCR) can be defined so that actions are performed to resolve specific situations (e.g., situations of increased traffic, exhaustion of resources, or occurrence of congestion). A PDR can define an FCR by limiting the specificity of target traffic to which the FCR should be applied. Table 1 below describes a structure in which an identifier for an FCR is added so that traffic corresponding to a PDR defined in 3GPP can apply the FCR. However, an FCR can also be defined by adding action conditions and action contents of an FCR to existing rules in addition to a method of newly defining the FCR separately from existing rules. AttributeDescriptionCommentN4 Session IDIdentifies the N4 session associated to this PDR. NOTE 5.Rule IDUnique identifier to identify this rule.PrecedenceDetermines the order, in which the detection information of all rules is applied.PacketSource interfaceContains the values "access side", "core side", "SMF", "N6-LAN", "5G VN internal".Combination of UE IP address (together with Network instance, if necessary), CN tunnel info,DetectionUE IP addressOne IPv4 address and / or one IPv6 prefix with prefix length (NOTE 3).packet filter set, application identifier, Ethernet PDU SessionInformation.NOTE 4.Network instance (NOTE 1)Identifies the Network instance associated with the incoming packet.Information and QFI are used for traffic detection.Source interface identifies theCN tunnel infoCN tunnel info on N3, N9 interfaces, i.e. F-TEID.interface for incoming packetsPacket Filter SetDetails see clause 5.7.6.where the PDR applies, e.g. from access side (i.e.up-link),Application identifierfrom core side (i.e. down-link),QoS Flow IDContains the value of 5QI or non-standardized QFI.from SMF, from N6-LAN (i.e. theEthernet PDU Session InformationRefers to all the (DL) Ethernet packets matching an Ethernet PDU session, as further described in clause 5.6.10.2 and in TS 29.244 .

[0065] .DN), or from "5G VN internal" (i.e. local switch).Framed Route InformationRefers to Framed Routes defined in clause 5.6.14.Details like all the combination possibilities on N3, N9 interfaces are left for stage 3 decision.FQDN Filter for DNS QueryContains one or more FQDN, FQDN range, and / or any FQDN.The FQDN or FQDN range only used for detection of plain DNS Query message (i.e. not subject to ciphering). The usage is described in TS 23.548

[0130] .Protocol DescriptionIndicates service protocol used by the flow (NOTE 8).Packet replication and detection carry on informationPacket replication skip information NOTE 7Contains UE address indication or N19 / N6 indication. If the packet matches the packet replication skip information, i.e. source address of the packet is the UE address or the packet has been received on the interface in the packet replication skip information, the UP function neither creates a copy of the packet nor applies the corresponding processing (i.e. FAR, QER, URR).Otherwise the UPF performs a copy and applies the corresponding processing (i.e. FAR, QER, URR).NOTE 6Carry on indicationInstructs the UP function to continue the packet detection process, i.e. lookup of the other PDRs.Outer header removalInstructs the UP function to remove one or more outer header(s) (e.g. IP+UDP+GTP, IP + possibly UDP, VLAN tag), from the incoming packet.Any extension header shall be stored for this packet.Forwarding Action Rule ID (NOTE 2)The Forwarding Action Rule ID identifies a forwarding action that has to be applied.Multi-Access Rule ID (NOTE 2)The Multi-Access Rule ID identifies an action to be applied for handling forwarding for a MA PDU Session.List of Usage Reporting Rule ID(s)Every Usage Reporting Rule ID identifies a measurement action that has to be applied.List of QoS Enforcement Rule ID(s)Every QoS Enforcement Rule ID identifies a QoS enforcement action that has to be applied.List of Flow Control Rule ID(s)Describe flow control mechanisms applied to QoS flow such as packet drop, ECN marking, Traffic Shaping, AQM strategy. describes information about FCR. FCR can include information about performance indicators or parameters to be monitored, conditions for performing actions, and actions or action IDs to be applied. AttributeDescriptionCommentN4 Session IDIdentifies the N4 session associated to this FCR.Rule IDUnique identifier to identify this information.Monitoring ParametersIdentifies the parameters to monitor, and this parameter will be used by condition check.ConditionDescribe when the action will be triggered, by the combination of Monitoring parameters. It could contain threshold, range, and logical statements.e.g.)UPF - Buffer Size, Burstiness, Average Queuing delay, CPU / Memory resource usageActionDescribe the action. Action could be referred using Action ID, or Action can be described. Action can contain probability how much portion of packets will be applied for this action.e.g.) if Queuing delay > 1ms, then mark CE(11) with 50% probability. The performance indicators or parameters to be monitored may include, for example, buffer size, buffer usage, total queuing delay, CPU / memory usage, etc. The conditions for performing an action may be composed of a combination of performance indicators or parameters to be monitored. If the conditions for performing an action are satisfied, the defined action may be performed. For example, if the total queuing delay exceeds 1 ms, an action may be performed to mark a CE (11) indicating a congestion situation in the ECN field of the header in the packet of data transmitted and received with a 50% probability. FIG. 8 illustrates a method for controlling QoS flow, TCP flow, or QUIC flow by utilizing the above-described FCR. Referring to FIG. 8, in operation 805, a terminal may transmit a PDU session establishment request message to an SMF entity to establish a new PDU session. For example, the terminal may transmit the PDU session establishment request message to the SMF entity through a connected base station and an AMF (access and mobility management function) entity. The transmission procedure of the PDU session establishment request message may follow the message transmission procedure and method in the control plane of the 5G core network. However, the present invention is not limited thereto. According to one embodiment of the present disclosure, the PDU session establishment request message may include information such as a version of TCP or QUIC supported by the terminal, whether an ECN function is supported in a PDU session connection, a queue control indicator based on RTT, etc. Such information may be information necessary for interworking between the terminal and a network entity, and not all of the information must be included in the PDU session establishment request message and may be included selectively. Meanwhile, such information may be different from the information included in the PDU session establishment request message of operation 510 of FIG. 5. In addition, the PDU session establishment request message may include information of DNN and S-NSSAI that are generally included when transmitting a PDU session establishment request message, and may also include other information for establishing a PDU session. In operation 810, the SMF entity may perform an operation to determine a PDU session to be established based on a PDU session establishment request message received from the terminal. For example, the SMF entity may perform operations such as searching for data to be subscribed to, authenticating a PDU session to be established, selecting a PCF (policy control function) entity, and establishing an SM policy. In operation 815, the SMF entity can generate PDR and FCR for QoS flow that may exist in PDU session to be generated for throughput control or congestion control. The SMF entity can generate PDR and FCR by adding an identifier for FCR to PDR defined in existing 3GPP as in described above and defining monitoring factors, conditions, actions, etc. of FCR as in . Unlike the SMF entity in FIG. 5, the SMF entity in FIG. 8 defines FCR as a new data control rule and can additionally define information about FCR in PDR to utilize it. UPF entity and base station set by FCR or new data control rule similar to FCR can monitor data transmission status, etc. and control throughput accordingly. In addition, the SMF entity can select a UPF entity and a path to establish a PDU session requested from the terminal. In one example, the SMF entity can select a UPF entity and a path supporting the ECN function based on the information received from the terminal in operation 805. The SMF entity can acquire candidate UPF entities according to an NRF or local policy, and select an NF (network function) profile that can support the ECN function among the NF profiles of each of the candidate UPF entities. At this time, the SMF entity can select a UPF entity matching the selected NF profile as the UPF entity used to establish the PDU session. At operation 820, the SMF entity can establish an N4 session to transmit rules related to actual packet processing to the UPF entity selected at operation 815. The SMF entity can transmit rules such as PDR, FCR generated at operation 815, as N4 session information to the UPF entity, such as FAR (forwarding action rule) and QER (QoS enforcement rule) to identify and manage QoS flows to be processed in the newly established PDU session. In one example, an SMF entity may transmit to a UPF entity factors related to activation of an ECN function, including the factors in the N4 session information. The factors related to activation of the ECN function may include a first ECN indicator for causing the UPF entity to process an ECN field and second ECN indicators for causing a network device to process the ECN field. The first ECN indicator may also be referred to as a 5G ECN indicator, and the second ECN indicator may also be referred to as a TN ECN indicator. However, the invention is not limited thereto. Factors related to activation of the ECN function may be transmitted from the SMF entity to the UPF entity by adding a new field to existing PDR, FAR, QER, etc. However, a method of transmitting factors related to activation of the ECN function is not limited thereto, and may be transmitted separately. The first ECN indicator may instruct the UPF entity and the RAN to set the CE flag by marking 11 in the ECN field in the header of the user packet, depending on the resource status, to indicate a congestion condition. For example, if the current link utilization of the UPF entity exceeds a certain threshold, the UPF entity may set the CE flag by marking 11 in the ECN field in the header of the user packet. In one example, when the ECN field is utilized for not only congestion control but also L4S (low latency, low loss, and scalable throughput), the first ECN indicator may instruct to change the ECT flag setting to prevent an incorrect operation from being performed. For example, when the ECN field is marked with 01 to indicate L4S traffic for L4S, a collision may occur depending on whether there is L4S traffic, so it may be instructed to modify the ECT flag of the ECN field to 10 to avoid the collision. The operation to prevent the collision when the ECN field is used for L4S traffic and congestion control may be performed at a step in which a UPF entity receives a packet from a server through a link of an N6 interface, or at a step in which a RAN receives a packet from a terminal and transfers it to the UPF entity through an N3 interface. The second ECN indicator can instruct operations related to the ECN function in a transport network (TN) where the UPF processes a QoS flow or a PDU session. In one example, in order to utilize ECN in a transport network, it may need to be processed in the process of generating an additional packet header, such as VXLAN, so that a packet passes through a virtual network. The second ECN indicator can set ECT so that a UPF entity can utilize an ECN field of a packet header in the process of transmitting and receiving packets, and can instruct to copy the CE to the IP header of a user packet located at the innermost position when a CE is set in the outermost header in the process of decapsulating packets for a virtual network. In addition, the second ECN indicator can be used when a network device of a virtual network performs ECN marking on packets transmitted and received between a UPF entity and a base station. In one example, an SMF entity can transmit an ECN tuning parameter to a UPF entity by adding it to N4 session information. The ECN tuning parameter can include information on a condition for performing ECN marking by the UPF entity, the RAN, or a transmission network device between the UPF entity and the RAN. For example, the ECN tuning parameter can include information on a condition for marking CE with a 30% probability when a buffer capable of accommodating packets of the UPF entity is 50% or more, or for marking CE with a 100% probability when a buffer capable of accommodating packets of the UPF entity is 80% or more. The ECN tuning parameter transmitted to the UPF entity can specifically include combinations of monitoring factors, thresholds, and ECN marking probabilities according to the thresholds for buffers capable of accommodating packets of the UPF or RAN. In operation 825, if the PDU session is successfully established, the SMF entity may transmit a PDU session establishment success message to the terminal. In one example, the SMF entity may include factors related to the activation of the ECN function transmitted in operation 820 in the PDU session establishment success message and transmit it to the base station. Alternatively, the SMF entity may transmit N2 session information to the base station via the AMF entity, including factors related to the activation of the ECN function. In one example, an SMF entity can transmit an ECN tuning parameter in a PDU session establishment success message or N2 information. The ECN tuning parameter transmitted to the RAN may specifically include combinations of a buffer size, a received signal strength, a monitoring factor for the RAN's buffer that comprehensively considers user mobility, a threshold value, and an ECN marking probability according to the threshold value. Since the RAN can additionally consider information about radio resources compared to the UPF entity, information included in the ECN tuning parameter transmitted from the SMF entity to the UPF entity in operation 820 may be different from information included in the ECN tuning parameter transmitted from the SMF entity to the RAN in operation 825. That is, factors to be monitored to determine whether an ECN condition is satisfied may be different between the UPF entity and the RAN. In one example, the SMF entity may additionally transmit information about factors to be monitored, conditions, and actions to be taken when conditions are satisfied for packets in the QoS flow that are the target of the PDU session establishment success message or N2 information. The transmitted information may include different contents from the monitoring factors, conditions, and actions included in the FCR transmitted by the SMF entity to the UPF entity in operation 820. In operation 830, in addition to transmitting the PDU session establishment success message or separate N2 session information in operation 825, the SMF entity may transmit a message requesting PDU session modification, including a first ECN indicator, a second ECN indicator, an ECN tuning parameter, and a rule for performing congestion control. Operations 825 and 830 are not sequential operations and are illustrated in FIG. 8 to explain methods for transmitting the first ECN indicator, the second ECN indicator, the ECN tuning parameter, and the rule for performing congestion control to the base station. The SMF may transmit the information, including the first ECN indicator, the second ECN indicator, the ECN tuning parameter, and the rule for performing congestion control, to the base station through at least one of operations 825 or 830. Thereafter, when uplink data or downlink data is transmitted and received between entities of a terminal, a base station, and a core network, an operation that explicitly indicates a congestion control situation may be performed. Since this operation is the same as the operations in FIGS. 6 and 7 described above, a detailed description thereof will be omitted. In operation 835, the UPF entity that receives rules related to congestion control from the SMF entity can apply the rules to the QoS flow. The UPF entity can search for resource conditions based on the rules. For example, the UPF entity can search for resources such as buffer size, buffer usage, total queuing delay, and CPU / memory usage based on the received FCR, and among these, the UPF entity can search for a situation in which a condition in which the total queuing delay exceeds 1ms occurs. In operation 840, the UPF entity may perform an action defined in the rules related to congestion control if a condition defined in the rules related to congestion control is satisfied. The type of the action may be, for example, setting a packet hold time, ECN marking, or randomly dropping a packet. In one example, if a condition occurs in which the total queuing delay defined in the FCR exceeds 1 ms, the UPF entity may perform an action of marking a CE (11) indicating a congestion situation in an ECN field of a header in a packet of data transmitted and received with a probability of 50%. In operation 845, the base station, which has received rules related to congestion control from the SMF entity, such as the operation of the UPF entity in operation 835, can apply the rules to the QoS flow. The base station can search for resource conditions based on the rules. However, the rules related to congestion control received by the base station may be different from the rules received by the UPF entity. In addition, the base station can limit the QoS flow to be searched based on the QFI (QoS flow identifier) ​​received in operation 825 or operation 830. In operation 850, the base station may perform an action defined in the rules related to congestion control if a condition defined in the rules related to congestion control is satisfied, such as the operation of the UPF entity in operation 850. The type of action may be, for example, setting a packet hold time, ECN marking, or randomly dropping a packet. UPF entities or base stations can detect situations where traffic increases, resources are exhausted, or congestion is expected through rules related to congestion control, and can effectively prevent congestion in the network by controlling congestion or controlling transmission volume in such situations. Through this, the network can prevent problems such as service quality degradation and service delay that may occur due to congestion. FIG. 9 illustrates the operation of a user plane function (UPF) entity according to one embodiment of the present disclosure. In operation 910, the UPF entity may receive N4 session information including an ECN activation indicator and an ECN tuning parameter from the SMF entity. At this time, the UPF entity receiving information about the ECN activation indicator and the ECN tuning parameter from the SMF entity may mean a UPF entity selected based on ECN information that the SMF entity can support in a PDU session connection. In one example, the ECN information that the SMF entity can support in a PDU session connection may include at least one of whether the terminal supports ECN, information about a TCP (transmission control protocol) version, or whether to control transmission based on a round trip time (RTT). According to one embodiment of the present disclosure, the ECN activation indicator may include a first ECN indicator and a second ECN indicator. The first ECN indicator may instruct a UPF entity or a base station to perform ECN marking for indicating congestion in an ECN field of an inner header within a packet of data. The second ECN indicator may instruct a UPF entity or a base station to perform ECN marking for indicating congestion in an ECN field of an outer header within a packet of data, or to copy a value on which ECN marking is performed in an ECN field of an outer header to an ECN field of an inner header. ECN tuning parameters may include information about the conditions under which a UPF entity, a RAN, or a transport network device between a UPF entity and a RAN performs ECN marking. At operation 920, the UPF entity can identify a QoS flow to which activation of ECN related functions is to be applied based on an ECN activation indicator received from an SMF entity. At operation 930, the UPF entity can perform data communication based on the ECN activation indicator and ECN tuning parameters. In one example, a UPF entity may receive downlink data from a server. Thereafter, the UPF entity, which receives a packet through the N6 interface, may perform its own ECN function related algorithm and, based on the result, mark the ECN field in the IP header of the packet as 11 to set the CE flag. The UPF entity may encapsulate the downlink data and transmit it to the base station in order to transmit the downlink data to the base station through the virtual network. In one example, a UPF entity can receive uplink data from a base station through a virtual network. The UPF entity can remove a packet header, such as VXLAN, added by the base station to transmit data to the UPF entity through the virtual network. In addition, the UPF entity can copy an ECN field value of an outer header of a packet of uplink data marked with CE (11) to an IP header of a GTP-U header if the second ECN indicator is true. Thereafter, the UPF entity can perform ECN marking with CE (11) on the inner header of a packet to be transmitted to a terminal based on its own algorithm or an ECN tuning parameter received from the SMF entity in operation 910. The UPF entity can transmit uplink data with ECN marking with CE on the inner header to a server of a data network. FIG. 10 illustrates the operation of a terminal according to one embodiment of the present disclosure. In operation 1010, the terminal may transmit a PDU session establishment request message including ECN information supportable in the PDU session connection to the SMF entity through the base station. In operation 1020, the terminal may receive a PDU session establishment response message including an ECN activation indicator and ECN tuning parameters from an SMF entity through a base station. According to one embodiment of the present disclosure, the ECN activation indicator may include a first ECN indicator and a second ECN indicator as described in operation 920 of FIG. 9. Descriptions of the first ECN indicator and the second ECN indicator have been described above, and are therefore omitted. In operation 1030, the terminal can perform data communication based on the received PDU session establishment response message. In one example, a terminal may receive downlink data from a server through a UPF entity, a base station, connected to a virtual network. The downlink data received by the terminal may be a packet whose inner header is marked with ECN as CE(11) by the base station. The terminal may check the ECN field marked in the inner header of the packet of the downlink data and control the congestion situation according to the ECN field value. For example, a terminal that checks the ECN field marked with CE(11) in the inner header may perform an operation for controlling the congestion situation, such as reducing the size of a congestion window. In one example, a server of a data network can receive uplink data from a terminal through a UPF entity or a base station connected to a virtual network. The uplink data received by the server can be a packet whose inner header is marked with ECN (11) by the UPF entity. The server can check the ECN field marked in the inner header of the uplink data packet and control the congestion situation according to the ECN field value. FIG. 11 illustrates the structure of a core network entity according to one embodiment of the present disclosure. A network entity according to one embodiment of the present disclosure may include a processor (1120) that controls the overall operation of the network entity, a transceiver (1100) including a transmitter and a receiver, and a memory (1110). Of course, the present invention is not limited to the above example, and the network entity may include more or fewer components than the configuration illustrated in FIG. 11. According to one embodiment of the present disclosure, the transceiver (1100) can transmit and receive signals with at least one of other network entities or terminals. The signals transmitted and received with at least one of other network entities or terminals can include control information and data. According to one embodiment of the present disclosure, the processor (1120) can control a network entity to perform any one of the operations of the above-described embodiments. Meanwhile, the processor (1120), the memory (1110), and the transceiver (1100) do not necessarily have to be implemented as separate modules, and of course, they can be implemented as a single component in the form of a single chip. In addition, the processor (1120) and the transceiver (1100) can be electrically connected. In addition, the processor (1120) can be an AP (Application Processor), a CP (Communication Processor), a circuit, an application-specific circuit, or at least one processor. According to one embodiment of the present disclosure, the memory (1110) can store data such as a basic program, an application program, and setting information for the operation of a network entity. In particular, the memory (1110) provides the stored data upon a request of the processor (1120). The memory (1110) can be configured as a storage medium or a combination of storage media such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, the memory (1110) can be plural. In addition, the processor (1120) can perform the above-described embodiments based on a program for performing the above-described embodiments of the present disclosure stored in the memory (1110). FIG. 12 illustrates the structure of a base station (1200) according to various embodiments of the present disclosure. Referring to FIG. 12, the base station (1200) includes a communication unit (1210), a storage unit (1220), and a control unit (1230). The communication unit (1210) performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit (1210) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the communication unit (1210) encodes and modulates a transmission bit stream to generate complex symbols. In addition, when receiving data, the communication unit (1210) restores a reception bit stream by demodulating and decoding a baseband signal. In addition, the communication unit (1210) up-converts a baseband signal into an RF (radio frequency) band signal and transmits it through an antenna, and down-converts an RF band signal received through the antenna into a baseband signal. To this end, the communication unit (1210) may include a transmitting filter, a receiving filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In addition, the communication unit (1210) may include a plurality of transmission and reception paths. Furthermore, the communication unit (1210) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit (1210) may be composed of a digital unit and an analog unit, and the analog unit may be composed of a plurality of sub-units according to operating power, operating frequency, etc. The communication unit (1210) can transmit and receive signals. To this end, the communication unit (1210) can include at least one transceiver. For example, the communication unit (1210) can transmit a synchronization signal, a reference signal, system information, a message, control information, or data. In addition, the communication unit (1210) can perform beamforming. The communication unit (1210) transmits and receives signals as described above. Accordingly, all or part of the communication unit (1210) may be referred to as a 'transmitter', a 'receiver', or a 'transmitter-receiver'. In addition, in the following description, transmission and reception performed through a wireless channel are used to mean that processing as described above is performed by the communication unit (1210). The storage unit (1220) stores data such as basic programs, application programs, and setting information for the operation of the base station. The storage unit (1220) may include a memory. The storage unit (1220) may be composed of volatile memory, nonvolatile memory, or a combination of volatile memory and nonvolatile memory. In addition, the storage unit (1220) provides stored data according to a request from the control unit (1230). The control unit (1230) controls the overall operations of the base station (1200). For example, the control unit (1230) transmits and receives signals through the communication unit (1210). In addition, the control unit (1230) records and reads data in the storage unit (1220). In addition, the control unit (1230) can perform functions of a protocol stack required by a communication standard. To this end, the control unit (1230) can include at least one processor. The configuration of the base station (1200) illustrated in FIG. 12 is only an example of a base station, and examples of base stations that perform various embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 12. That is, some configurations may be added, deleted, or changed according to various embodiments. In FIG. 12, the base station (1200) is described as a single entity, but the present disclosure is not limited thereto. The base station (1200) according to various embodiments of the present disclosure may be implemented to form an access network having not only an integrated deployment but also a distributed deployment. According to one embodiment, the base station may be divided into a central unit (CU) and a digital unit (DU), and the CU may be implemented to perform upper layer functions (e.g., packet data convergence protocol (PDCP), RRC)) and the DU may be implemented to perform lower layer functions (e.g., medium access control (MAC), physical (PHY)). The DU of the base station may form beam coverage on a wireless channel. FIG. 13 illustrates the structure of a terminal (1300) according to various embodiments of the present disclosure. The configuration illustrated in Fig. 13 can be understood as the configuration of a terminal (1300). Terms such as '... unit', '... device', etc. used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software. Referring to FIG. 13, the terminal (1300) includes a communication unit (1310), a storage unit (1320), and a control unit (1330). The communication unit (1310) performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit (1310) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the communication unit (1310) encodes and modulates a transmission bit stream to generate complex symbols. In addition, when receiving data, the communication unit (1310) restores a reception bit stream by demodulating and decoding a baseband signal. In addition, the communication unit (1310) up-converts a baseband signal into an RF band signal and then transmits it through an antenna, and down-converts an RF band signal received through the antenna into a baseband signal. For example, the communication unit (1310) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In addition, the communication unit (1310) may include a plurality of transmission / reception paths. Furthermore, the communication unit (1310) may include an antenna unit. The communication unit (1310) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit (1310) may be composed of digital circuits and analog circuits (e.g., radio frequency integrated circuits (RFICs)). Here, the digital circuits and analog circuits may be implemented in one package. In addition, the communication unit (1310) may include a plurality of RF chains. The communication unit (1310) may perform beamforming. The communication unit (1310) may apply beamforming weights to a signal to be transmitted / received in order to impart directionality to the signal according to the settings of the control unit (1330). According to one embodiment, the communication unit (1310) may include an RF (radio frequency) block (or RF unit). The RF block may include first RF circuitry associated with the antenna and second RF circuitry associated with baseband processing. The first RF circuitry may be referred to as RF-A (antenna). The second RF circuitry may be referred to as RF-B (baseband). In addition, the communication unit (1310) can transmit and receive signals. To this end, the communication unit (1310) can include at least one transceiver. The communication unit (1310) can receive a downlink signal. The downlink signal may include a synchronization signal (SS), a reference signal (RS) (e.g., demodulation (DM)-RS, phase tracking reference signal (PTRS), system information (e.g., MIB, SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, or downlink data, etc.). In addition, the communication unit (1110) may transmit an uplink signal. The uplink signal may include a random access related signal (e.g., a random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), a reference signal (e.g., a sounding reference signal (SRS), DMRS, PTRS), or a power headroom report (PHR). Additionally, the communication unit (1310) may include different communication modules to process signals of different frequency bands. Furthermore, the communication unit (1310) may include multiple communication modules to support multiple different wireless access technologies. For example, the different wireless access technologies may include bluetooth low energy (BLE), wireless fidelity (Wi-Fi), wifi gigabyte (WiGig), cellular networks (e.g., long term evolution (LTE), new radio (NR), etc.). In addition, the different frequency bands may include super high frequency (SHF) (e.g., 2.5 GHz, 5 GHz) bands, millimeter wave (mm wave) (e.g., 38 GHz, 60 GHz, etc.) bands. In addition, the communication unit (1310) may use the same type of wireless access technology on different frequency bands (e.g., unlicensed bands for licensed assisted access (LAA), citizen broadband radio service (CBRS) (e.g., 3.5 GHz)). The communication unit (1310) transmits and receives signals as described above. Accordingly, all or part of the communication unit (1310) may be referred to as a 'transmitter', a 'receiver', or a 'transmitter-receiver'. In addition, in the following description, transmission and reception performed through a wireless channel are used to mean that processing as described above is performed by the communication unit (1310). The storage unit (1320) stores data such as basic programs, application programs, and setting information for the operation of the terminal (1300). The storage unit (1320) may be composed of volatile memory, nonvolatile memory, or a combination of volatile memory and nonvolatile memory. In addition, the storage unit (1320) provides stored data according to a request from the control unit (1330). The control unit (1330) controls the overall operations of the terminal (1300). For example, the control unit (1330) transmits and receives signals through the communication unit (1310). In addition, the control unit (1330) records and reads data in the storage unit (1320). In addition, the control unit (1330) can perform functions of a protocol stack required by a communication standard. To this end, the control unit (1330) can include at least one processor. The control unit (1330) can include at least one processor or microprocessor, or can be a part of a processor. In addition, a part of the communication unit (1310) and the control unit (1330) can be referred to as a CP. The control unit (1330) can include various modules for performing communication. According to various embodiments, the control unit (1330) can control the terminal to perform operations according to various embodiments. Meanwhile, the embodiments of the present invention disclosed in this specification and drawings are only specific examples presented to easily explain the technical content of the present invention and help in understanding the present invention, and are not intended to limit the scope of the present invention. In other words, it is obvious to those skilled in the art that other modified examples based on the technical idea of ​​the present invention are possible. In addition, each of the above embodiments can be combined and operated as needed. As described above, a method performed by a user plane function (UPF) entity in a wireless communication system according to various embodiments disclosed in the present document may include the steps of receiving, from a session management function (SMF) entity, N4 session information including an explicit congestion notification (ECN) activation indicator and an ECN tuning parameter, identifying a QoS flow to which activation of an ECN related function is to be applied based on the ECN activation indicator, and performing data communication based on the ECN activation indicator and the ECN tuning parameter. According to various embodiments disclosed in the present document, an ECN activation indicator includes a first ECN indicator and a second ECN indicator, wherein the first ECN indicator instructs a UPF entity or a base station to perform ECN marking to indicate whether an ECN field of an inner header of data is congested, and the second ECN indicator can instruct the UPF entity or the base station to perform ECN marking to indicate whether an ECN field of an outer header of the data is congested, or to copy a value ECN-marked in the ECN field of the outer header to the ECN field of the inner header of the data. According to various embodiments disclosed in the present document, the method may further include the steps of receiving downlink data from a server, identifying whether an ECN marking condition is satisfied for the downlink data, performing ECN marking on an ECN field of an outer header in the downlink data if the ECN marking condition is satisfied, and transmitting the ECN-marked downlink data to a base station through a virtual network. According to various embodiments disclosed in the present document, a method may include the steps of receiving uplink data with ECN marking in an ECN field of an outer header from a base station through a virtual network, performing a step of copying a value with ECN marking in the ECN field of the outer header in the uplink data to an ECN field of an inner header in the uplink data, performing ECN marking in the ECN field of the inner header in the uplink data if the received uplink data satisfies an ECN marking condition indicated by an ECN tuning parameter, and transmitting the uplink data with ECN marking in the ECN field of the inner header to a server. According to various embodiments disclosed in this document, a UPF entity represents a UPF entity selected based on ECN information supportable in a PDU session connection received by an SMF entity from a user equipment, and the ECN information supportable in the PDU session connection may include at least one of whether the terminal supports ECN, information about a transmission control protocol (TCP) version, or whether transmission is controlled based on a round trip time (RTT). As described above, a method performed by a user equipment in a wireless communication system according to various embodiments disclosed in the present document includes the steps of transmitting a PDU session establishment request message including ECN information supportable in a PDU session connection to a session management function (SMF) entity via a base station, receiving a PDU session establishment response message including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter from the SMF entity via the base station, and performing data communication based on the PDU session establishment response message, wherein the PDU session establishment response message may be characterized in that it includes identification information for a QoS flow to which the base station applies activation of an ECN related function based on the ECN activation indicator. According to various embodiments disclosed in the present document, an ECN activation indicator includes a first ECN indicator and a second ECN indicator, wherein the first ECN indicator instructs a user plane function (UPF) entity or a base station to perform ECN marking for indicating congestion in an ECN field of an inner header of data, and the second ECN indicator instructs the UPF entity or the base station to perform ECN marking for indicating congestion in an ECN field of an outer header of the data, or to copy a value marked ECN in the ECN field of the outer header to the ECN field of the inner header of the data. According to various embodiments disclosed in the present document, a method includes the steps of receiving downlink data from a base station, identifying an ECN field of an inner header in the received downlink data, and controlling a congestion situation according to the identified ECN field, wherein the ECN field of the inner header in the downlink data may be marked by the base station with ECN marking to indicate whether there is congestion. According to various embodiments disclosed in this document, the received downlink data may be ECN marked by the UPF entity to indicate congestion in the ECN field of the outer header. According to various embodiments disclosed in this document, the step of controlling a congestion situation may include the step of identifying a congestion situation when an ECN marking is indicated by a predetermined value, and the step of performing an operation of reducing the size of a congestion window according to the identified congestion situation. As described above, in a wireless communication system according to various embodiments disclosed in the present document, a user plane function (UPF) entity may include at least one transceiver and a controller coupled with the at least one transceiver. The controller may be configured to receive N4 session information including an explicit congestion notification (ECN) activation indicator and an ECN tuning parameter from a session management function (SMF) entity, identify a QoS flow to which activation of an ECN related function is to be applied based on the ECN activation indicator, and perform data communication based on the ECN activation indicator and the ECN tuning parameter. According to various embodiments disclosed in the present document, an ECN activation indicator includes a first ECN indicator and a second ECN indicator, wherein the first ECN indicator instructs a UPF entity or a base station to perform ECN marking to indicate whether an ECN field of an inner header of data is congested, and the second ECN indicator can instruct the UPF entity or the base station to perform ECN marking to indicate whether an ECN field of an outer header of the data is congested, or to copy a value ECN-marked in the ECN field of the outer header to the ECN field of the inner header of the data. According to various embodiments disclosed in the present document, the controller may be further configured to receive downlink data from a server, identify whether an ECN marking condition is satisfied for the downlink data, perform ECN marking on an ECN field of an outer header in the downlink data if the ECN marking condition is satisfied, and transmit the ECN-marked downlink data to a base station through a virtual network. According to various embodiments disclosed in the present document, a controller may be further configured to receive uplink data with ECN marking in an ECN field of an outer header from a base station through a virtual network, copy a value with ECN marking in the ECN field of the outer header in the uplink data to an ECN field of an inner header in the uplink data, and perform ECN marking on the ECN field of the inner header in the uplink data if the received uplink data satisfies an ECN marking condition indicated by an ECN tuning parameter, and transmit the uplink data with ECN marking performed in the ECN field of the inner header to a server. According to various embodiments disclosed in this document, a UPF entity represents a UPF entity selected based on ECN information supportable in a PDU session connection received by an SMF entity from a user equipment, and the ECN information supportable in the PDU session connection may include at least one of whether the terminal supports ECN, information about a transmission control protocol (TCP) version, or whether transmission is controlled based on a round trip time (RTT). As described above, in a wireless communication system according to various embodiments disclosed in the present document, a user equipment may include at least one transceiver and a controller coupled with the at least one transceiver. The controller may transmit, to a session management function (SMF) entity via a base station, a PDU session establishment request message including ECN information supportable in a PDU session connection, and receive, from the SMF entity via the base station, a PDU session establishment response message including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter, and is configured to perform data communication based on the PDU session establishment response message, and the PDU session establishment response message may be characterized in that it includes identification information for a QoS flow to which the base station applies activation of an ECN related function based on the ECN activation indicator. According to various embodiments disclosed in the present document, an ECN activation indicator includes a first ECN indicator and a second ECN indicator, wherein the first ECN indicator instructs a user plane function (UPF) entity or a base station to perform ECN marking for indicating congestion in an ECN field of an inner header of data, and the second ECN indicator instructs the UPF entity or the base station to perform ECN marking for indicating congestion in an ECN field of an outer header of the data, or to copy a value marked ECN in the ECN field of the outer header to the ECN field of the inner header of the data. According to various embodiments disclosed in the present document, the controller is further configured to receive downlink data from a base station, identify an ECN field of an inner header in the received downlink data, and control a congestion situation according to the identified ECN field, wherein the ECN field of the inner header in the downlink data may be marked by the base station to indicate whether there is congestion. According to various embodiments disclosed in this document, the received downlink data may be ECN marked by the UPF entity to indicate congestion in the ECN field of the outer header. According to various embodiments disclosed in this document, the controller may be further configured to identify a congestion situation when the ECN marking is indicated by a predetermined value, and perform an operation of reducing the size of a congestion window according to the identified congestion situation.

Claims

1. A method performed by a user plane function (UPF) entity in a wireless communication system, A step of receiving N4 session information including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter from a SMF (session management function) entity; A step for identifying a QoS flow to which activation of an ECN-related function is to be applied based on the above ECN activation indicator; and A method comprising the step of performing data communication based on the ECN activation indicator and ECN tuning parameter.

2. In claim 1, The above ECN activation indicator includes a first ECN indicator and a second ECN indicator, The above first ECN indicator instructs the UPF entity or base station to perform ECN marking indicating whether there is congestion in the ECN field of the cabinet header of the data. A method wherein the second ECN indicator instructs the UPF entity or the base station to perform ECN marking to indicate whether there is congestion in an ECN field of an outer header of the data, or to copy an ECN-marked value in the ECN field of the outer header to the ECN field of the inner header of the data.

3. In claim 1, the method comprises: A step of receiving downlink data from a server; A step for identifying whether the ECN marking condition is satisfied for the above downlink data; If the above ECN marking condition is satisfied, a step of performing ECN marking on the ECN field of the outer header in the downlink data; and A method further comprising the step of transmitting the ECN-marked downlink data to the base station through the virtual network.

4. In claim 1, the method comprises: A step of receiving uplink data with ECN marking in the ECN field of the outer header from a base station through a virtual network; A step of copying a value marked as ECN in the ECN field of the outer header in the uplink data to the ECN field of the inner header in the uplink data; If the received uplink data satisfies the ECN marking condition indicated by the ECN tuning parameter, a step of performing ECN marking on the ECN field of the cabinet header in the uplink data; and A method comprising the step of transmitting, to a server, uplink data with ECN marking performed in an ECN field of the cabinet header.

5. In claim 1, The above UPF entity represents a UPF entity selected based on ECN information that can be supported in a PDU session connection received from a terminal (user equipment) by the above SMF entity. A method in which ECN information that can be supported in the above PDU session connection includes at least one of whether the terminal supports ECN, information about the TCP (transmission control protocol) version, or whether transmission is controlled based on RTT (round trip time).

6. In a method performed by a terminal (user equipment) in a wireless communication system, A step of transmitting a PDU session establishment request message including ECN information that can be supported in a PDU session connection to a session management function (SMF) entity via a base station; A step of receiving a PDU session establishment response message including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter from the SMF entity through the base station; and A step of performing data communication based on the above PDU session establishment response message is included. A method, characterized in that the PDU session establishment response message includes identification information for a QoS flow to which the base station applies activation of an ECN-related function based on the ECN activation indicator.

7. In claim 6, The above ECN activation indicator includes a first ECN indicator and a second ECN indicator, The above first ECN indicator instructs the UPF (user plane function) entity or the base station to perform ECN marking indicating whether there is congestion in the ECN field of the inner header of the data. A method wherein the second ECN indicator instructs the UPF entity or the base station to perform ECN marking to indicate whether there is congestion in an ECN field of an outer header of the data, or to copy an ECN-marked value in the ECN field of the outer header to the ECN field of the inner header of the data.

8. In claim 6, the method comprises: A step of receiving downlink data from the base station; A step of identifying an ECN field of an inner header within the received downlink data; and According to the above identified ECN field, a step for controlling a congestion situation is included, A method wherein the ECN field of the cabinet header in the above downlink data is marked by the base station to indicate whether there is congestion.

9. In claim 8, A method wherein the received downlink data is marked with ECN marking to indicate whether there is congestion in the ECN field of the outer header by the UPF entity.

10. In claim 8, the step of controlling the congestion situation comprises: If the above ECN marking is displayed as a predetermined value, a step of identifying it as a congested situation; and A method comprising the step of performing an operation of reducing the size of a congestion window according to the identified congestion situation.

11. In a wireless communication system, for a UPF (user plane function) entity, at least one transceiver; and A controller coupled with at least one transceiver, The above controller, Receive N4 session information including ECN (explicit congestion notification) activation indicator and ECN tuning parameters from SMF (session management function) entity, Based on the above ECN activation indicator, identify the QoS flow to which activation of ECN-related functions is to be applied. A UPF entity configured to perform data communication based on the above ECN activation indicator and ECN tuning parameters.

12. In claim 11, The above ECN activation indicator includes a first ECN indicator and a second ECN indicator, The above first ECN indicator instructs the UPF entity or base station to perform ECN marking indicating whether there is congestion in the ECN field of the cabinet header of the data. The second ECN indicator instructs the UPF entity or the base station to perform ECN marking to indicate whether there is congestion in the ECN field of the outer header of the data, or to copy the ECN-marked value in the ECN field of the outer header to the ECN field of the inner header of the data.

13. In claim 1, the controller, Receive downlink data from the server, Identifies whether the ECN marking condition is satisfied for the above downlink data, If the ECN marking condition is satisfied for the above downlink data, ECN marking is performed on the ECN field of the outer header in the above downlink data, A UPF entity further configured to transmit downlink data with the ECN marking to a base station through a virtual network.

14. In a wireless communication system, in the terminal (user equipment), at least one transceiver; and A controller coupled with at least one transceiver, The above controller, Transmit a PDU session establishment request message including ECN information that can be supported in the PDU session connection to the SMF (session management function) entity via the base station, Receive a PDU session establishment response message including an ECN (explicit congestion notification) activation indicator and an ECN tuning parameter from the SMF entity through the base station, Based on the above PDU session establishment response message, data communication is set to be performed, A terminal, characterized in that the PDU session establishment response message includes identification information for a QoS flow to which the base station applies activation of an ECN-related function based on the ECN activation indicator.

15. In claim 14, The above ECN activation indicator includes a first ECN indicator and a second ECN indicator, The above first ECN indicator instructs the UPF (user plane function) entity or the base station to perform ECN marking indicating whether there is congestion in the ECN field of the inner header of the data. The second ECN indicator instructs the UPF entity or the base station to perform ECN marking to indicate whether there is congestion in the ECN field of the outer header of the data, or to copy the ECN-marked value in the ECN field of the outer header to the ECN field of the inner header of the data.

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