Electronic device and method for performing handover of packet data session

Abstract

Am electronic device comprising a communication circuit, a processor and a memory for storing instructions is disclosed. When executed by the processor, the instructions can instruct the electronic device to: establish a packet data session via a non-cellular access network and a first CN node of a cellular network; determine whether a first packet loss rate related to the packet data session exceeds a first threshold value; on the basis that the first packet loss rate exceeds the first threshold value, determine whether a second packet loss rate of the non-cellular access network exceeds a second threshold value; on the basis that the second packet loss rate exceeds the second threshold value, perform handover from the non-cellular access network to a cellular access network with respect to the packet data session; and, on the basis that the second packet loss rate does not exceed the second threshold value, perform handover from the first CN node to a second CN node with respect to the packet data session.

Description

Electronic device and method for performing packet data session handover

[0001] Embodiments of the present disclosure relate to an electronic device and method for performing a handover of a packet data session.

[0002] Following LTE (long term evolution) / LTE-Advanced (LTE-A) for 4th generation (4G) mobile communication, next-generation, namely 5th generation (5G) NR (new radio) mobile communication technology has been developed.

[0003] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands ('above 6 GHz'), known as millimeter wave (mmWave), such as 28 GHz and 39 GHz. In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, implementation in the terahertz band (e.g., the 3 terahertz (3 THz) band at 95 GHz) is being considered to achieve transmission speeds 50 times faster and ultra-low latency reduced to one-tenth compared to 5G mobile communication technology.

[0004] In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC), technologies included beamforming and massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands; support for various numerologies (such as operating multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources; initial access techniques to support multi-beam transmission and broadband; definition and operation of band-width parts (BWPs); new channel coding methods such as low-density parity check (LDPC) codes for high-volume data transmission and polar codes for reliable transmission of control information; L2 pre-processing; and networks providing dedicated networks specialized for specific services. Standardization of network slicing and the like has been carried out.

[0005] Discussions are underway to improve and enhance the performance of early 5G mobile communication technology in consideration of the requirements of 5G mobile communication technology, and physical layer standardization is in progress for technologies such as V2X (vehicle-to-everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (new radio unlicensed), which aims for system operation in unlicensed bands that meets various regulatory requirements; UE power saving, which is a terminal-satellite direct communication technology for securing coverage in areas where communication with the terrestrial network is impossible; and positioning.

[0006] The information described above may be provided as related art for the purpose of aiding understanding of the present disclosure. No claim or determination is made as to whether any of the foregoing may be applied as prior art related to the present disclosure.

[0007] Embodiments of the present disclosure may provide an electronic device and method for performing a handover of a packet data session.

[0008] Embodiments of the present disclosure may provide an electronic device and method for handing over a packet data session connected through a non-cellular access network.

[0009] Embodiments of the present disclosure may provide an electronic device and method for performing a handover based on packet loss rates of a non-cellular access network segment and a cellular network backend segment.

[0010] An electronic device according to one embodiment of the present disclosure may include a communication circuit, at least one processor, and a memory for storing instructions. When the instructions are executed individually or collectively by the at least one processor, the electronic device may establish a packet data session through the communication circuit via a first CN (core network) node of a non-cellular access network and a cellular network. When the instructions are executed individually or collectively by the at least one processor, the electronic device may determine whether a first packet loss rate associated with the packet data session exceeds a first threshold. When the instructions are executed individually or collectively by the at least one processor, the electronic device may determine whether a second packet loss rate of the non-cellular access network exceeds a second threshold based on the first packet loss rate exceeding the first threshold. When the above instructions are executed individually or collectively by the at least one processor, the electronic device may perform a handover from the non-cellular access network to the cellular access network through the communication circuit for the packet data session based on the second packet loss rate exceeding the second threshold. When the above instructions are executed individually or collectively by the at least one processor, the electronic device may perform a handover from the first CN node to the second CN node of the cellular network through the communication circuit for the packet data session based on the second packet loss rate not exceeding the second threshold.

[0011] A method performed by an electronic device according to one embodiment of the present disclosure may include: establishing a packet data session through a first CN node of a non-cellular access network and a cellular network; determining whether a first packet loss rate associated with the packet data session exceeds a first threshold; determining whether a second packet loss rate of the non-cellular access network exceeds a second threshold based on the first packet loss rate exceeding the first threshold; performing a handover from the non-cellular access network to the cellular access network through the communication circuit for the packet data session based on the second packet loss rate exceeding the second threshold; and performing a handover from the first CN node to the second CN node of the cellular network through the communication circuit for the packet data session based on the second packet loss rate not exceeding the second threshold.

[0012] In a non-transient computer-readable storage medium storing one or more programs according to one embodiment of the present disclosure, the one or more programs may include instructions that, when executed individually or collectively by at least one processor, cause an electronic device to: establish a packet data session through a first CN (core network) node of a non-cellular access network and a cellular network; determine whether a first packet loss rate associated with the packet data session exceeds a first threshold; determine whether a second packet loss rate of the non-cellular access network exceeds a second threshold based on the first packet loss rate exceeding the first threshold; perform a handover from the non-cellular access network to the cellular access network for the packet data session based on the second packet loss rate exceeding the second threshold; and perform a handover from the first CN node to the second CN node of the cellular network through the communication circuit for the packet data session based on the second packet loss rate not exceeding the second threshold.

[0013] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0014] In relation to the description of the drawings, the same or similar reference numerals may be used for identical or similar components.

[0015] FIG. 1 is a block diagram of an electronic device in a network environment according to various embodiments.

[0016] FIG. 2 illustrates a network structure for LTE mobile communication according to one embodiment of the present disclosure.

[0017] FIGS. 3a and 3b illustrate a downlink and uplink bearer structure according to one embodiment of the present disclosure.

[0018] FIGS. 4a and FIGS. 4b are drawings for illustrating packet filtering according to one embodiment of the present disclosure.

[0019] FIG. 5 illustrates a network structure for 5G mobile communication according to one embodiment of the present disclosure.

[0020] FIGS. 6a and 6b illustrate a QoS framework for an LTE network and a 5G network according to one embodiment of the present disclosure.

[0021] FIG. 7 is a sequence diagram illustrating a signaling procedure for establishing a PDU session according to one embodiment of the present disclosure.

[0022] FIG. 8 is a sequence diagram illustrating a procedure for generating an IPSec SA according to one embodiment of the present disclosure.

[0023] FIG. 9 illustrates QoS mapping in N3IWF according to one embodiment of the present disclosure.

[0024] FIG. 10 is a flowchart illustrating a handover procedure from Wi-Fi to cellular according to one embodiment of the present disclosure.

[0025] FIG. 11 is a flowchart illustrating a handover procedure from cellular to Wi-Fi according to one embodiment of the present disclosure.

[0026] FIG. 12 is a flowchart illustrating an operation to perform a handover according to one embodiment of the present disclosure.

[0027] FIG. 13 is a diagram illustrating the connectivity of a packet data session according to one embodiment of the present disclosure.

[0028] FIG. 14 is a diagram illustrating a handover determination for packet loss occurrence intervals according to one embodiment of the present disclosure.

[0029] FIG. 15 is a flowchart illustrating a procedure for handing over from N3IWF to ePDG according to one embodiment of the present disclosure.

[0030] FIG. 16 is a flowchart illustrating a procedure for handing over from ePDG to N3IWF according to one embodiment of the present disclosure.

[0031] FIG. 17 is a flowchart illustrating a communication procedure after a handover to an ePDG according to one embodiment of the present disclosure.

[0032] FIGS. 18a and FIGS. 18b are flowcharts illustrating a handover procedure based on TCP packet loss rate and DNS packet loss rate according to one embodiment of the present disclosure.

[0033] FIG. 19 is a drawing for illustrating a ping test according to one embodiment of the present disclosure.

[0034] FIG. 20 is a flowchart illustrating a handover procedure based on RTP packet loss rate and ping packet loss rate according to one embodiment of the present disclosure.

[0035] FIG. 21 is a flowchart illustrating a handover procedure based on the packet loss rate and ping packet loss rate of another PDU session according to one embodiment of the present disclosure.

[0036] FIG. 22 is a flowchart illustrating a handover procedure based on the packet loss rate and ping packet loss rate of another PDU session according to one embodiment of the present disclosure.

[0037] FIG. 23 is a block diagram showing the configuration of an electronic device according to one embodiment of the present disclosure.

[0038] FIG. 24 is a sequence diagram illustrating a handover procedure according to one embodiment of the present disclosure.

[0039] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In describing the embodiments of the present disclosure, specific descriptions of related known functions or configurations are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Furthermore, terms used below are defined considering their functions in the embodiments of the present disclosure, and these may vary depending on the intent or practice of the user or operator. Therefore, such definitions should be based on the content throughout the present disclosure.

[0040] It should be noted that technical terms used in this disclosure are used merely to describe one embodiment and are not intended to limit this disclosure. Alternatively, unless specifically defined otherwise in this disclosure, technical terms used in this disclosure shall be interpreted in the sense generally understood by those skilled in the art to which this disclosure pertains, and shall not be interpreted in an overly broad or overly narrow sense. Alternatively, technical terms used in this disclosure may be understood as being replaced by other technical terms understood by those skilled in the art. General terms used in the embodiments of this disclosure shall be interpreted according to their prior definitions or according to the context, and shall not be interpreted in an overly narrow sense.

[0041] Singular expressions used in this disclosure may include plural expressions unless the context clearly indicates otherwise. In this disclosure, terms such as “composed” or “comprising” should not be interpreted as necessarily including all of the various components or operations described in the specification, and should be interpreted as some of the components or operations may not be included, or additional components or operations may be included.

[0042] Terms including ordinal numbers, such as first or second as used in this disclosure, may be used to describe various components, but said components should not be limited by said terms. Such terms may be used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the rights of this disclosure, the first component may be named the second component, and similarly, the second component may be named the first component.

[0043] When it is stated that one component is "connected" or "connected" to another component, it may be directly connected or connected to that other component, or there may be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0044] Hereinafter, embodiments according to the present disclosure will be described with reference to the attached drawings. Identical or similar components regardless of drawing symbols are given the same reference numeral, and redundant descriptions thereof will be omitted. In describing the embodiments of the present disclosure, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions may obscure the essence of the present disclosure. It should be noted that the attached drawings are intended only to facilitate understanding of the embodiments of the present disclosure and should not be interpreted as limiting the present disclosure. The present disclosure should be interpreted as extending to all modifications, equivalents, and substitutions in addition to the attached drawings.

[0045] In this disclosure, embodiments will be described using an electronic device as an example, but the electronic device may be referred to as a terminal, mobile station, mobile equipment (ME), user equipment (UE), user terminal (UT), subscriber station (SS), wireless device, handheld device, or access terminal (AT). In the embodiments of this disclosure, the electronic device may be a device equipped with communication functions, such as a mobile phone, personal digital assistant (PDA), smartphone, wireless modem, or laptop.

[0046] FIG. 1 is a block diagram of an electronic device (101) in a network environment (100) according to various embodiments.

[0047] Referring to FIG. 1, in a network environment (100), an electronic device (101) may communicate with an electronic device (102) through a first network (198) (e.g., a short-range wireless communication network) or with an electronic device (104) or a server (108) through a second network (199) (e.g., a long-range wireless communication network). According to one embodiment, the electronic device (101) may communicate with the electronic device (104) through a server (108). According to one embodiment, the electronic device (101) may include a processor (120), memory (130), input module (150), sound output module (155), display module (160), audio module (170), sensor module (176), interface (177), connection terminal (178), haptic module (179), camera module (180), power management module (188), battery (189), communication module (190), subscriber identification module (196), or antenna module (197). In some embodiments, at least one of these components (e.g., connection terminal (178)) may be omitted from the electronic device (101), or one or more other components may be added. In some embodiments, some of these components (e.g., sensor module (176), camera module (180), or antenna module (197)) may be integrated into a single component (e.g., display module (160)).

[0048] The processor (120) can control at least one other component (e.g., hardware or software component) of the electronic device (101) connected to the processor (120) by executing software (e.g., program (140)), for example, and can perform various data processing or operations. According to one embodiment, as at least part of the data processing or operations, the processor (120) can store commands or data received from other components (e.g., sensor module (176) or communication module (190)) in volatile memory (132), process the commands or data stored in volatile memory (132), and store the resulting data in non-volatile memory (134). According to one embodiment, the processor (120) may include a main processor (121) (e.g., central processing unit or application processor) or an auxiliary processor (123) that can operate independently or together with it (e.g., graphics processing unit, neural processing unit (NPU), image signal processor, sensor hub processor, or communication processor). For example, if the electronic device (101) includes a main processor (121) and an auxiliary processor (123), the auxiliary processor (123) may be configured to use lower power than the main processor (121) or to be specialized for a designated function. The auxiliary processor (123) may be implemented separately from the main processor (121) or as part thereof.

[0049] The auxiliary processor (123) may control at least some of the functions or states associated with at least one component of the electronic device (101) (e.g., display module (160), sensor module (176), or communication module (190)) on behalf of the main processor (121) while the main processor (121) is in an inactive (e.g., sleep) state, or together with the main processor (121) while the main processor (121) is in an active (e.g., application execution) state. According to one embodiment, the auxiliary processor (123) (e.g., image signal processor or communication processor) may be implemented as part of another functionally related component (e.g., camera module (180) or communication module (190)). According to one embodiment, the auxiliary processor (123) (e.g., neural network processing unit) may include a hardware structure specialized for processing an artificial intelligence model. The artificial intelligence model may be generated through machine learning. Such learning may be performed, for example, on the electronic device (101) itself where the artificial intelligence is performed, or through a separate server (e.g., server (108)). The learning algorithm may include, for example, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning, but is not limited to the examples described above. The artificial intelligence model may include a plurality of artificial neural network layers.An artificial neural network may be a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), a deep Q-network, or a combination of two or more of the above, but is not limited to the examples described above. In addition to the hardware structure, the artificial intelligence model may include a software structure, either additionally or substantially.

[0050] The memory (130) can store various data used by at least one component of the electronic device (101) (e.g., processor (120) or sensor module (176)). The data may include, for example, input data or output data for software (e.g., program (140)) and related commands. The memory (130) may include volatile memory (132) or non-volatile memory (134).

[0051] The program (140) may be stored as software in memory (130) and may include, for example, an operating system (142), middleware (144), or an application (146).

[0052] The input module (150) can receive commands or data to be used for a component of the electronic device (101) (e.g., processor (120)) from outside the electronic device (101) (e.g., user). The input module (150) may include, for example, a microphone, a mouse, a keyboard, a key (e.g., a button), or a digital pen (e.g., a stylus pen).

[0053] The sound output module (155) can output a sound signal to the outside of the electronic device (101). The sound output module (155) may include, for example, a speaker or a receiver. The speaker may be used for general purposes, such as multimedia playback or recording playback. The receiver may be used to receive incoming calls. According to one embodiment, the receiver may be implemented separately from the speaker or as part thereof.

[0054] The display module (160) can visually provide information to an external (e.g., user) of the electronic device (101). The display module (160) may include, for example, a display, a holographic device, or a projector and a control circuit for controlling said device. According to one embodiment, the display module (160) may include a touch sensor configured to detect a touch, or a pressure sensor configured to measure the intensity of the force generated by said touch.

[0055] The audio module (170) can convert sound into an electrical signal or, conversely, convert an electrical signal into sound. According to one embodiment, the audio module (170) can acquire sound through the input module (150) or output sound through the sound output module (155) or an external electronic device (e.g., electronic device (102)) (e.g., speaker or headphones) connected directly or wirelessly to the electronic device (101).

[0056] The sensor module (176) can detect the operating state of the electronic device (101) (e.g., power or temperature) or the external environmental state (e.g., user state) and generate an electrical signal or data value corresponding to the detected state. According to one embodiment, the sensor module (176) may include, for example, a gesture sensor, a gyroscope sensor, a barometric pressure sensor, a magnetic sensor, an accelerometer sensor, a grip sensor, a proximity sensor, a color sensor, an IR (infrared) sensor, a biosensor, a temperature sensor, a humidity sensor, or an illuminance sensor.

[0057] The interface (177) may support one or more specified protocols that can be used for the electronic device (101) to be connected directly or wirelessly to an external electronic device (e.g., electronic device (102)). According to one embodiment, the interface (177) may include, for example, a high definition multimedia interface (HDMI), a universal serial bus (USB) interface, an SD card interface, or an audio interface.

[0058] The connection terminal (178) may include a connector through which the electronic device (101) can be physically connected to an external electronic device (e.g., electronic device (102)). According to one embodiment, the connection terminal (178) may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector).

[0059] The haptic module (179) can convert an electrical signal into a mechanical stimulus (e.g., vibration or movement) or an electrical stimulus that the user can perceive through tactile or kinesthetic senses. According to one embodiment, the haptic module (179) may include, for example, a motor, a piezoelectric element, or an electric stimulation device.

[0060] The camera module (180) can capture still images and video. According to one embodiment, the camera module (180) may include one or more lenses, image sensors, image signal processors, or flashes.

[0061] The power management module (188) can manage the power supplied to the electronic device (101). According to one embodiment, the power management module (188) can be implemented, for example, as at least part of a power management integrated circuit (PMIC).

[0062] The battery (189) can supply power to at least one component of the electronic device (101). According to one embodiment, the battery (189) may include, for example, a non-rechargeable primary battery, a rechargeable secondary battery, or a fuel cell.

[0063] The communication module (190) can support the establishment of a direct (e.g., wired) communication channel or a wireless communication channel between an electronic device (101) and an external electronic device (e.g., electronic device (102), electronic device (104), or server (108)), and the performance of communication through the established communication channel. The communication module (190) may include one or more communication processors that operate independently of the processor (120) (e.g., application processor) and support direct (e.g., wired) communication or wireless communication. According to one embodiment, the communication module (190) may include a wireless communication module (192) (e.g., cellular communication module, short-range wireless communication module, or GNSS (global navigation satellite system) communication module) or a wired communication module (194) (e.g., LAN (local area network) communication module, or power line communication module). The corresponding communication module among these communication modules can communicate with an external electronic device (104) through a first network (198) (e.g., a short-range communication network such as Bluetooth, WiFi (wireless fidelity) direct, or IrDA (infrared data association)) or a second network (199) (e.g., a legacy cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., a LAN or WAN)). These various types of communication modules may be integrated into a single component (e.g., a single chip) or implemented as multiple separate components (e.g., multiple chips). The wireless communication module (192) can identify or authenticate the electronic device (101) within a communication network such as the first network (198) or the second network (199) using subscriber information (e.g., International Mobile Subscriber Identifier (IMSI)) stored in the subscriber identification module (196).

[0064] The wireless communication module (192) can support 5G networks and next-generation communication technologies following 4G networks, for example, new radio access technology. NR access technology can support high-speed transmission of high-capacity data (enhanced mobile broadband (eMBB)), minimization of terminal power and connection of multiple terminals (massive machine type communications (mMTC)), or high reliability and low latency (ultra-reliable and low-latency communications (URLLC)). The wireless communication module (192) can support a high-frequency band (e.g., mmWave band) to achieve a high data transmission rate, for example. The wireless communication module (192) can support various technologies for securing performance in the high-frequency band, such as beamforming, massive MIMO (multiple-input and multiple-output), full-dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, or large-scale antenna. The wireless communication module (192) can support various requirements specified in the electronic device (101), external electronic device (e.g., electronic device (104)), or network system (e.g., second network (199)). According to one embodiment, the wireless communication module (192) can support a Peak data rate (e.g., 20 Gbps or more) for realizing eMBB, loss coverage (e.g., 164 dB or less) for realizing mMTC, or U-plane latency (e.g., downlink (DL) and uplink (UL) each 0.5 ms or less, or round trip 1 ms or less) for realizing URLLC.

[0065] An antenna module (197) can transmit a signal or power to or from an external source (e.g., an external electronic device). According to one embodiment, the antenna module (197) may include an antenna comprising a radiator made of a conductor or a conductive pattern formed on a substrate (e.g., a PCB). According to one embodiment, the antenna module (197) may include a plurality of antennas (e.g., an array antenna). In this case, at least one antenna suitable for a communication method used in a communication network, such as a first network (198) or a second network (199), may be selected from the plurality of antennas, for example, by a communication module (190). A signal or power may be transmitted or received between the communication module (190) and an external electronic device through the selected at least one antenna. According to some embodiments, in addition to the radiator, other components (e.g., a radio frequency integrated circuit (RFIC)) may be additionally formed as part of the antenna module (197).

[0066] According to various embodiments, the antenna module (197) may form a mmWave antenna module. According to one embodiment, the mmWave antenna module may include a printed circuit board, an RFIC disposed on or adjacent to a first surface (e.g., bottom surface) of the printed circuit board and capable of supporting a specified high frequency band (e.g., mmWave band), and a plurality of antennas (e.g., array antennas) disposed on or adjacent to a second surface (e.g., top surface or side surface) of the printed circuit board and capable of transmitting or receiving a signal of the specified high frequency band.

[0067] At least some of the above components can be connected to each other via a communication method between peripheral devices (e.g., bus, GPIO (general purpose input and output), SPI (serial peripheral interface), or MIPI (mobile industry processor interface)) and exchange signals (e.g., commands or data) with each other.

[0068] According to one embodiment, commands or data may be transmitted or received between the electronic device (101) and an external electronic device (104) through a server (108) connected to a second network (199). Each of the external electronic devices (102, or 104) may be the same or a different type of device as the electronic device (101). According to one embodiment, all or part of the operations performed on the electronic device (101) may be performed on one or more of the external electronic devices (102, 104, or 108). For example, if the electronic device (101) needs to perform a function or service automatically or in response to a request from a user or another device, the electronic device (101) may request one or more external electronic devices to perform at least part of the function or service instead of performing the function or service itself or additionally. One or more external electronic devices that receive the above request may execute at least part of the requested function or service, or additional function or service related to the request, and transmit the result of the execution to the electronic device (101). The electronic device (101) may provide the result as is or additionally processed as at least part of the response to the request. For this purpose, for example, cloud computing, distributed computing, mobile edge computing (MEC), or client-server computing technology may be used. The electronic device (101) may provide ultra-low latency services using, for example, distributed computing or mobile edge computing. In another embodiment, the external electronic device (104) may include an Internet of Things (IoT) device. The server (108) may be an intelligent server using machine learning and / or neural networks. According to one embodiment, the external electronic device (104) or the server (108) may be included within a second network (199).The electronic device (101) can be applied to intelligent services (e.g., smart home, smart city, smart car, or healthcare) based on 5G communication technology and IoT-related technology.

[0069] Cellular wireless communication standards, such as 3GPP (3rd generation partnership project), can define cellular networks based on LTE mobile communication technology or 5G NR mobile communication technology. Cellular networks can be configured to interwork with non-cellular networks not defined in the cellular wireless communication standards. Non-cellular networks may include, for example, WiBro access networks or Wi-Fi networks. Cellular wireless communication standards may support, for example, ePDG (evolved packet data gateway) or N3IWF (non-3GPP interworking function) as network nodes for interworking between non-cellular networks and cellular core networks.

[0070] FIG. 2 illustrates a network structure for LTE mobile communication according to one embodiment of the present disclosure.

[0071] Referring to FIG. 2, an electronic device (101) (e.g., user equipment: UE) can use communication services such as calls or the internet through a cellular network (e.g., a 3GPP network (220)) and / or a non-cellular network (e.g., a non-3GPP network (210)).

[0072] In one embodiment, the 3GPP network (220) may include a 3GPP access network (AN) (222), a serving gateway (S-GW) (224), a packet data network (PDN) gateway (PGW or P-GW) (226), a home subscriber server (HSS) (228), an internet protocol (IP) service network (232), a policy and charging rules function (PCRF) (234), an authentication, authorization and accounting (AAA) server (236), and / or an ePDG (230).

[0073] A non-3GPP network (210) may include a trusted non-3GPP access network (212) and / or a non-trusted non-3GPP access network (214). A non-3GPP network (210) may mean an access network that is not standardized in a cellular wireless communication standard such as 3GPP. Network nodes constituting a non-3GPP network (210) may be classified as a trusted non-3GPP access network (212) or a non-trusted non-3GPP access network (214) depending on whether a 3GPP operator can provide trusted security.

[0074] In one embodiment, the 3GPP access network (222) may include at least one base station (e.g., eNB (evolved node B) (304) of FIG. 3a) and may correspond to a cellular access network.

[0075] In one embodiment, the serving gateway (224) acts as a boundary point between the 3GPP access network (222) and the evolved packet core (EPC) (e.g., serving gateway (224), PDN gateway (226), HSS (228), PCRF (234), AAA server (246), and / or ePDG (230)), and may be responsible for maintaining a data path between the eNB (e.g., eNB (304) in FIG. 3a) and the PDN gateway (226). When the electronic device (101) moves across the boundary of the area served by the eNB (e.g., eNB (304) in FIG. 3a), the serving gateway (224) may serve as a local mobility anchor point.

[0076] In one embodiment, the serving gateway (224) can route packets for mobility within the E-UTRAN (evolved-UMTS (universal mobile telecommunications system) terrestrial radio access network). Additionally, the serving gateway (224) can function as an anchor point for mobility with other 3GPP networks (e.g., UTRAN or GERAN (GSM (global system for mobile communication) / EDGE (enhanced data rates for global evolution) radio access network)).

[0077] In one embodiment, the PDN gateway (226) may correspond to a termination point of a data interface toward a packet data network (PDN) (e.g., the Internet). The PDN gateway (226) may support policy enforcement features, packet filtering, and charging support, etc. The PDN gateway (226) may be connected to an IP service network (232) for providing an operator's IP services (e.g., IP multimedia subsystem (IMS) and packet-switched streaming service (PSS)). Additionally, the PDN gateway (226) can serve as an anchor point for mobility management between the 3GPP network (220) and the non-3GPP network (210) (e.g., a trusted non-3GPP access network (212) such as an I-WLAN (interworking wireless local area network), or a trusted non-3GPP access network (214) such as a CDMA (code division multiple access) network).

[0078] In the example of FIG. 1, the serving gateway (224) and the PDN gateway (226) are shown as being composed of separate gateways, but the serving gateway (224) and the PDN gateway (226) may be implemented as a single gateway.

[0079] HSS (228) may be a server that stores and manages subscriber information.

[0080] The PCRF (234) can be responsible for determining policy control and billing control based on the flow. The PCRF (234) can generate PCC (policy and charging control) rules for per-user billing and transmit them to the PDN gateway (226).

[0081] In one embodiment, the ePDG (230) is a gateway that enables interoperability between a 3GPP network (220) and a non-3GPP network (210), and can provide security between a non-cellular access network (e.g., a trusted non-3GPP access network (212) or a non-trusted non-3GPP access network (214)) accessed by an electronic device (101) and a core network node of the 3GPP network (e.g., a PDN gateway (226)).

[0082] In one embodiment, an electronic device (101) having IP capability can access a 3GPP network (220) and / or a non-3GPP network (210), and can access an IP service network (232) provided by an operator via various network nodes within the EPC (e.g., a PDN gateway (226) and / or an ePDG (230)).

[0083] In one embodiment, the ePDG (230) can provide a secure communication link (e.g., an IPSec (IP security) tunnel) between the EPC and a non-3GPP network (210) (e.g., a trusted non-3GPP access network (212) or a non-trusted non-3GPP access network (214)) to which the electronic device (101) connects. The ePDG (230) can maintain quality of service even when the electronic device (101) is connected to the non-3GPP network (210) and can provide a consistent user experience to the user regardless of the connection location of the electronic device (101).

[0084] In one embodiment, the ePDG (230) can protect communication between the electronic device (101) and the EPC using an IPSec tunnel, and support handover when the electronic device (220) moves from a non-3GPP network (210) to a 3GPP network to ensure service continuity.

[0085] FIGS. 3a and 3b illustrate a downlink and uplink bearer structure according to one embodiment of the present disclosure.

[0086] Referring to FIGS. 3a and 3b, an electronic device (101) (e.g., UE) can run an application (app) (302)) and establish a packet data session (e.g., PDN connection (310)) for said application. The electronic device (101) can receive downlink (DL) data or transmit uplink (UL) data from a data network (308) (e.g., the Internet) through the PDN connection (310).

[0087] In one embodiment, the PDN connection (310) may include a wireless bearer (312) between the electronic device (101) and the 3GPP access network (222) (e.g., eNB (304)) and an S5 / S8 bearer between the eNB (304) and the packet gateway (306) (e.g., PDN gateway (226)). S5 may mean an interface between the serving gateway (224) and the PDN gateway (226) when not roaming, and S8 may mean an interface between the serving gateway (224) and the PDN gateway (226) when roaming.

[0088] In one embodiment, the wireless bearer (312) may include a default bearer (312a) and / or at least one dedicated bearer (312b), and the S5 / S8 bearer (314a) may include a default bearer (314a) and / or at least one dedicated bearer (314b). The default bearers (312a, 314a) may be configured to provide best effort service, and the dedicated bearers (312b, 314b) may be configured to provide quality of service (QoS).

[0089] Referring to FIG. 3a, for a downlink, a packet gateway (306) (e.g., PDN gateway (226)) can filter (316) data traffic of one or more IP data flows (e.g., IP flow 1 (318a) and IP flow 2 (318b)) connected to a data network (308), and deliver the filtered data to bearers (e.g., default bearer (314a) and at least one dedicated bearer (314b)).

[0090] Referring to FIG. 3b, for an uplink, the electronic device (101) can filter (324) data traffic of one or more IP data flows (e.g., IP flow 3 (322a) and IP flow 4 (322b)) connected to the application (302), and transmit the filtered data to bearers (e.g., default bearer (312a) and at least one dedicated bearer (312b)).

[0091] In one embodiment, when the electronic device (101) is connected to a non-3GPP access network (e.g., Wi-Fi AP (502) of FIG. 5) rather than an eNB (304), the ePDG (230) can connect one or more bearers to the non-3GPP access network.

[0092] In one embodiment, the ePDG (230) may establish one or more IPSec security associations (SAs) per PDN connection. If one IPSec SA is established per PDN connection, all traffic between the electronic device (101) and the ePDG (230) may be transmitted through a single IPSec connection. If multiple IPSec SAs are established per PDN connection, all traffic between the electronic device (101) and the ePDG (230) may be transmitted through dedicated bearer-specific IPSec connections.

[0093] FIGS. 4a and FIGS. 4b are drawings for illustrating packet filtering according to one embodiment of the present disclosure.

[0094] Referring to FIG. 4a, an electronic device (101) (e.g., UE) can connect traffic flows (406) of an application or service layer (e.g., application / service layer (410)) to an IPSec SA (402) connected between the electronic device (101) and an ePDG (230). The ePDG (230) can filter (412) the uplink data traffic received through the IP tunnels of the IPSec SA (402) and then transmit the filtered uplink data traffic to the PDN gateway (226) through a communication link (404) (e.g., an S2b bearer or a GTP (General Packet Radio Service (GPRS) tunneling protocol) tunnel) between the ePDG (230) and the PDN gateway (226).

[0095] In one embodiment, the PDN gateway (226) can transmit the uplink data traffic to a data network (e.g., data network (308)) via traffic flows (408). In one embodiment, the PDN gateway (226) can filter (414) the downlink data traffic received from the data network (e.g., data network (308)) via traffic flows (408), and then transmit the filtered data traffic to an electronic device (101) via an ePDG (230).

[0096] Referring to FIG. 4b, an electronic device (101) (e.g., UE) can filter (422) uplink data traffic received through traffic flows (406) of an application or service layer (e.g., application / service layer (410)) and then transmit the filtered data traffic to the ePDG (230) through multiple IPSec SAs (420) connected between the electronic device (101) and the ePDG (230). The ePDG (230) can transmit uplink data traffic received through IP tunnels of the IPSec SAs (420) to the PDN gateway (226) through a communication link (404) (e.g., S2b bearer or GTP tunnel) between the ePDG (230) and the PDN gateway (226).

[0097] In one embodiment, the PDN gateway (226) can transmit the uplink data traffic to a data network (e.g., data network (308)) via traffic flows (408). In one embodiment, the PDN gateway (226) can filter (414) the downlink data traffic received from the data network (e.g., data network (308)) via traffic flows (408), and then transmit the filtered data traffic to an electronic device (101) via an ePDG (230).

[0098] [Table 1] below shows the method of connecting an IPSec SA between a terminal and an ePDG.

[0099] One IPSec SAS per PDN connection One IPSec SAS per 2b bearer IPSec SAS between UE and ePDG One or multiple operations All traffic between UE and ePDG is forwarded over a single IPSec connection IPSec is connected per dedicated bearer between UE and ePDG Uplink filter ePDGUE Downlink filter Gateway Gateway

[0100] FIG. 5 illustrates a network structure for 5G mobile communication according to one embodiment of the present disclosure. Referring to FIG. 5, an electronic device (101) (e.g., UE) is connected to a 5G Core (5G Core: 5GC) network (e.g., AMF (access and mobility management) (514) and UPF (user plane function) (516)) through a 5G access network (e.g., gNB (NR node B) (512) of FIG. 6b) as well as a non-cellular access network (e.g., Wi-Fi AP (502) of a WLAN (wireless local area network)), and can use communication services such as calls or the internet.

[0101] In one embodiment, the 5GC network may include an AMF (514), a UPF (user plane function) (516), an SMF (session management function) (518), an NSSF (network slice selection function) (522), an AUSF (authentication server function) (524), an NEF (network exposure function) (526), ​​an NRF (network function repository function) (528), a UDM (unified data management) (530), a PCF (policy control function) (532), and / or an N3IWF (non-3GPP interworking function) (510).

[0102] AMF (514) can manage network access and mobility.

[0103] The UPF (516) can provide packet routing and connectivity between an access network (e.g., a gNB (NR node B) or a Wi-Fi AP (502)) and a data network (520) (e.g., the Internet). The UPF (516) can perform all or part of the user plane functions of the serving gateway (224) and the PDN gateway (226) of the LTE network.

[0104] The SMF (518) can manage sessions between the electronic device (101) and the data network (520).

[0105] NSSF (522) can support network slicing.

[0106] AUSF (524) can authenticate and manage the electronic device (101).

[0107] NEF (526) can be responsible for service exposure in a 5G network.

[0108] NRF (528) can control the interoperability between network functions (NF) within a 5G network.

[0109] UDM (530) can store and manage user information, such as subscriber information, in a unified data repository (UDR).

[0110] PCF (532) can control the operator's policy and provide policy control over data packet flow.

[0111] The electronic device (101) can receive call and data services through a Wi-Fi network (e.g., Wi-Fi AP (502)) corresponding to a non-cellular (e.g., non-3GPP) access network. To connect the non-3GPP access to a 5G core (5GC) network (e.g., UPF (516)), an N3IWF (510) may be deployed.

[0112] N3IWF (510) can enable an electronic device (101) to access a 5G core network (e.g., UPF (516)) through a Wi-Fi network (e.g., Wi-Fi AP (502)) that corresponds to a non-3GPP access network. N3IWF (510) supports wired access networks as well as wireless access networks such as Wi-Fi, and unlike ePDG (230), can connect PDU (packet data unit) sessions through NAS (non-access stratum) signaling over a Wi-Fi network. N3IWF (510) can support network slicing and / or ATSSS (access traffic steering, switching, and splitting) for 5G mobile communication.

[0113] In one embodiment, signaling between the electronic device (101) and the AMF (514) for the control plane (CP) of the PDU session may be performed through an IPSec tunnel between the electronic device (101) and the N3IWF (510). In one embodiment, data flow for the user plane (UP) of the PDU session may be connected to the UPF (516) through an IPSec tunnel between the electronic device (101) and the N3IWF (510). The N3IWF (510) may provide GTP tunneling for the UP for connection with the UPF (516).

[0114] FIGS. 6a and 6b illustrate a QoS framework for an LTE network and a 5G network according to one embodiment of the present disclosure.

[0115] Referring to FIG. 6a, an electronic device (101) (e.g., UE) can establish a packet data session (e.g., PDN connection (610)) with a data network (e.g., data network (308)) via an eNB (304) and a packet gateway (306) (e.g., PDN gateway (226)). The PDN connection (310) can be mapped to a default bearer (612) (e.g., a data radio bearer (DRB) and an S5 / S8 bearer) and at least one dedicated bearer (614). The default bearer (612) can be mapped to an IP flow 1 (616a) between the electronic device (101) and the data network (308), and at least one dedicated bearer (614) can be mapped to at least one IP flow 2 (616b) between the electronic device (101) and the data network (308).

[0116] In one embodiment, for LTE mobile communication, each bearer (e.g., default bearer (612) or each dedicated bearer (614)) may be mapped to one QoS flow identified by a QoS class identifier (QCI), and each IP flow (e.g., IP flow 1 (616a) or IP flow 2 (616b)) may be mapped to an EPC bearer (e.g., default bearer (612) or each dedicated bearer (614)). Flow / bearer identification between the electronic device (101) and the data network (308) may be based on an EBI (EPS (evolved packet system) bearer ID).

[0117] Referring to FIG. 6b, an electronic device (101) (e.g., UE) can establish a packet data session (e.g., PDU session (620)) with a data network (e.g., data network (520)) via a gNB (512) and a UPF (516). The PDU session (620) may consist of at least one DRB (e.g., DRBs (622a, 622b)) between the electronic device (101) and the gNB (512) and an N3 tunnel (624) between the gNB (512) and the UPF (516). Here, N3 may refer to an interface between the gNB (512) and the UPF (516). IP flow 1 (626a) and IP flow 2 (626b) between the electronic device (101) and the data network (520) can be mapped to the DRB (622a) and N3 tunnel (624), and IP flow 3 (626c) and IP flow 4 (626d) between the electronic device (101) and the data network (520) can be mapped to the DRB (622b) and N3 tunnel (624).

[0118] In one embodiment, in a 5G mobile communication, each bearer (e.g., DRBs (622a, 622b)) is not coupled with a QoS flow, and each IP flow (e.g., IP flow 1 (626a), IP flow 2 (626b), IP flow 3 (626c) or IP flow 4 (626d)) can be mapped to one QoS flow (e.g., QoS flow 1, QoS flow 2, QoS flow 3, or QoS flow 4) identified by a 5G QoS identifier (5G QoS identifier: 5QI). Flow / bearer identification between the electronic device (101) and the data network (e.g., data network (520)) can be based on the QoS flow identifier (QFI).

[0119] [Table 2] below shows a comparison of QoS features in 5G networks and LTE networks.

[0120] 5G QoS SLTE QoS Mapping Decoupling QoS Flows and Bearers One-to-One Mapping Between Bearers and QoS Flows QoS Identification 5G QI QCIIP Data Flow QoS Flow EPC Bearer Flow / Bearer Identification QFIEBI Data Session PDU Session PDN Connection

[0121] FIG. 7 is a sequence diagram illustrating a signaling procedure for establishing a PDU session according to one embodiment of the present disclosure. Referring to FIG. 7, in operation 702, an electronic device (101) (e.g., a UE) may establish an IPSec security association (SA) for NAS signaling with an N3IWF (510) via a Wi-Fi AP (502). In operation 704, the electronic device (101) may transmit a PDU session establishment request message to an AMF (514) including a PDU session ID and / or a session and service continuity (SSC) mode. In operation 706, the AMF (514) may perform a local breakout (LBO) procedure or a home routing procedure with another network node of the 5G core network (e.g., a CN node (534)). The LBO procedure may be performed when the AMF (514) belongs to a visited network.

[0122] In operation 708, the AMF (514) may send an N2 PDU session request message to the N3IWF (510) that includes QoS profile(s), associated QFI, PDU session ID, and / or PDU session establishment accept. In operation 710, the N3IWF (510) may determine the number of IPSec child SA(s) for the PDU session based on the QoS profile(s). In operation 712, the N3IWF (510) may perform a procedure to establish an IPSec SA association with the electronic device (101) based on the determined number.

[0123] In operation 714, the AMF (514) may transmit to the electronic device (101) a PDU session establishment acceptance containing an IP address, an SSC mode, and / or authorized QoS rules. In operation 716, the electronic device (101) may configure QoS flows within the first IPSec child SA with the N3IWF (510). In operation 718, the electronic device (101) may configure QoS flows within the additional IPSec child SA(s) with the N3IWF (510).

[0124] FIG. 8 is a sequence diagram illustrating a procedure for generating an IPSec SA according to one embodiment of the present disclosure.

[0125] Referring to FIG. 8, in operation 800, an electronic device (101) (e.g., a UE) can perform an IPSec SA association procedure with N3IWF (510) via a Wi-Fi AP (502). In one embodiment, operation 800 may correspond to operation 712 of FIG. 7. Operation 800 may include operation 810 for establishing a first IPSec child SA and operation 820 for establishing additional IPSec child SA(s).

[0126] Operation 810 may include operations 812 and 814. In operation 812, N3IWF (510) may send an IKE_Create_Child_SA request to electronic device (101) to establish the first IPSec child SA, the request including QFI(s), PDU session ID, DSCP (differentiated services code point) value, additional QoS information, and / or UP IP address. In operation 814, electronic device (101) may send an IKE_Create_Child_SA response to N3IWF (510).

[0127] Operation 820 may include operations 822 and 824. In operation 822, N3IWF (510) may send an IKE_Create_Child_SA request to electronic device (101) including QFI(s), PDU session ID, DSCP value, additional QoS information, and / or UP IP address to establish an additional IPSec child SA. In operation 824, electronic device (101) may send an IKE_Create_Child_SA response to N3IWF (510).

[0128] FIG. 9 illustrates QoS mapping in N3IWF (510) according to one embodiment of the present disclosure.

[0129] Referring to FIG. 9, an electronic device (101) (e.g., a UE) can establish a PDU session (910) with a UPF (516) via an N3IWF (510). The PDU session (910) can be mapped to IPSec tunnels (912a, 912b) between the electronic device (101) and the N3IWF (510), and to a GTPU (GTP user plane) tunnel (914) between the N3IWF (510) and the UPF (516). QoS flow 1 between the electronic device (101) and the UPF (516) can be mapped to the IPSec tunnel (912a) and the GTPU tunnel (914), and QoS flow 2 and QoS flow 3 between the electronic device (101) and the UPF (516) can be mapped to the IPSec tunnel (912b) and the GTPU tunnel (914).

[0130] The electronic device (101) (e.g., UE) marks DSCP values ​​on uplink traffic and can map uplink traffic to QoS flows (e.g., QoS flows 1, 2, 3) using QoS rules.

[0131] N3IWF (510) marks DSCP values ​​on uplink traffic and downlink traffic and can map data (e.g., PDUs) from QoS flows 1, 2, and 3 to IPSec SAs based on QFI.

[0132] UPF (516) marks DSCP values ​​on downlink traffic and can map downlink traffic to QoS flows 1, 2, and 3 using PDR (packet detection rule).

[0133] In one embodiment, when an electronic device (101) uses a call or data service through a non-cellular access network (e.g., a Wi-Fi network), the electronic device (101) may select either an ePDG (230) or an N3IWF (510) to connect the non-cellular access network to a packet gateway (e.g., a PDN gateway (226) or a UPF (516)) of a cellular core network (e.g., an EPC or 5GC). In one embodiment, to use an IMS service for a voice call, the electronic device (101) may refer to a preference parameter within non-3GPP ANSI (access node selection information) and select an N3IWF (510) if the preference parameter indicates N3IWF preference, and select an ePDG (230) if the preference parameter indicates ePDG preference. In one embodiment, the electronic device (101) may preferentially select N3IWF (510) regardless of the preference parameter to use non-IMS services.

[0134] In one embodiment, the ePDG (230) may be used to support voice over Wi-Fi (or Wi-Fi calling) over a Wi-Fi network. The electronic device (101) may determine whether to connect to the ePDG (230) via a Wi-Fi network or to use a cellular network (e.g., an eNB (304) and an LTE core network) according to specified conditions (e.g., policy or wireless signal quality).

[0135] In one embodiment, the electronic device (101) may use an IMS service that supports VoLTE (voice over LTE) based on a session initiation protocol (SIP). In an LTE connection environment, the electronic device (101) may establish a PDN connection (e.g., an IMS PDN connection) with a data network (e.g., the Internet) to support the IMS service. That is, the VoLTE service may be performed based on the IMS PDN connection. When the electronic device (101) is connected to a Wi-Fi network, the electronic device (101) may decide whether to support the VoLTE service according to a policy, or to use the voice service through the ePDG (230) via the Wi-Fi network. If necessary, the electronic device (101) may perform a handover between the ePDG (230) and a network node of the LTE network (e.g., a PDN gateway (226)).

[0136] In one embodiment, the electronic device (101) can perform a handover between the ePDG (230) and a network node of the LTE network (e.g., PDN gateway (226)) according to specified conditions, whether in a call state or not in a call state (e.g., idle state).

[0137] In one embodiment, a handover between the ePDG (230) of an IMS PDN connection and the PDN gateway (226) may be triggered based on the signal strength of the wireless network. In one embodiment, the electronic device (101) may determine a handover between a non-cellular access network (e.g., Wi-Fi network) and a cellular access network (e.g., eNB) based on a wireless signal threshold (e.g., ROVEOUT_TH) for determining that the wireless network condition is bad and a wireless signal threshold (e.g., ROVEIN_TH) for determining that the wireless network condition is good.

[0138] FIG. 10 is a flowchart illustrating a handover procedure from Wi-Fi to cellular according to one embodiment of the present disclosure.

[0139] Referring to FIG. 10, in operation 1002, the electronic device (101) can determine whether the received signal quality of the Wi-Fi network is poor and the received signal quality of the cellular access network is good while performing a voice call over the Wi-Fi network. In one embodiment, the electronic device (101) can determine that the received signal quality of the Wi-Fi network is poor if the received signal quality (e.g., Wi-Fi RSSI (received signal strength indicator)) measured for the Wi-Fi network (e.g., Wi-Fi AP (502)) is smaller than a specified threshold (e.g., WIFI_ROVEOUT_TH). In one embodiment, the electronic device (101) may determine that the received signal quality of the cellular access network (e.g., eNB (304) or gNB (512)) is good if the received signal quality (e.g., RSRP (reference signals received power), RSRQ (reference signal received quality), and / or SNR (signal to noise ratio)) measured for the cellular access network is greater than a specified threshold (e.g., CELLULAR_ROVEIN_TH).

[0140] In one embodiment, the electronic device (101) may decide to hand over from the Wi-Fi network to the cellular access network when the real-time transport protocol (RTP) packet loss rate of a voice call is greater than a specified threshold (e.g., RTP_PACKET_LOSS_TH), regardless of the reception signal quality of the Wi-Fi network or the reception signal quality of the cellular access network.

[0141] In one embodiment, if the reception signal quality of the Wi-Fi network is poor and the reception signal quality of the cellular access network is good, or if the RTP packet loss rate of the voice call is greater than RTP_PACKET_LOSS_TH, the electronic device (101) may proceed to operation 1004 and hand over from the Wi-Fi network to the cellular access network. If the reception signal quality of the Wi-Fi network is good or the reception signal quality of the cellular access network is poor, or if the RTP packet loss rate of the voice call is not greater than RTP_PACKET_LOSS_TH, the electronic device (101) may proceed to operation 1006 and remain on the Wi-Fi network.

[0142] FIG. 11 is a flowchart illustrating a handover procedure from cellular to Wi-Fi according to one embodiment of the present disclosure.

[0143] Referring to FIG. 11, in operation 1102, the electronic device (101) can determine whether the received signal quality of the cellular access network is poor while performing a voice call (e.g., voice service over IMS). In one embodiment, the electronic device (101) can determine that the received signal quality of the cellular access network is poor if the received signal quality (e.g., RSRP, RSRQ, and / or SNR) measured for the cellular access network (e.g., eNB (304) or gNB (512)) is smaller than a specified threshold (e.g., CELLULAR_ROVEIN_TH).

[0144] In one embodiment, if the reception signal quality of the cellular access network is poor, the electronic device (101) may proceed to operation 1104 to hand over from the cellular access network to the Wi-Fi network. If the reception signal quality of the cellular access network is not poor, the electronic device (101) may proceed to operation 1106 to remain in the cellular access network.

[0145] In one embodiment, the electronic device (101) performs a handover according to the reception signal quality of a Wi-Fi network or a cellular access network, thereby supporting a calling service using Wi-Fi in a dead zone of a cellular network and enabling a seamless calling service through the handover.

[0146] In one embodiment, even if the RSSI of the Wi-Fi network measured by the electronic device (101) is good (e.g., greater than WIFI_ROVEOUT_TH), the quality of the voice call may be degraded if the packet loss rate of the voice call is high. Non-IMS PDU sessions using TCP (transmission control protocol) or QUIC (quick UDP (user data gram protocol) internet connections) may be very sensitive to packet loss rates compared to IMS PDU sessions using UDP.

[0147] [Table 3] below shows a comparison between IMS PDU sessions and non-IMS PDU sessions.

[0148] IMS PDU Session Rate - Purpose of IMS PDU Session Usage Call Services Internet Services (Games, Cloud Storage, Video, Browser, etc.) Sensitivity to Packet Loss Rate Low (UDP) High (TCP / QUIC) APP Yield (Throughput) Low High Cellular Core Network Usage

[0149] As an example, [Table 4] below shows TCP performance according to RTT (round trip time) and packet loss rate, and it can be seen that TCP performance decreases significantly as the packet loss rate increases.

[0150] Packet Loss Rate (%) RTT = 20ms RTT = 40ms RTT = 100ms 0.000 1940 Mbps 934 Mbps 915 Mbps 0.00 1931 Mbps 930 Mbps 897 Mbps 0.01 449 Mbps 354 Mbps 289 Mbps 0.163 Mbps 51 Mbps 21 Mbps

[0151] In one embodiment, the factors that increase the packet loss rate may be in the non-cellular access network segment (e.g., Wi-Fi network) or in the backend segment (e.g., ePDG (230) / PDN gateway (226) or N3IWF (510) / UPF (516)). When packet loss occurs in the backend segment, performing a handover from the Wi-Fi network to the cellular access network may increase the load on the cellular access network, leading to a waste of resources for the cellular access network, which is more expensive than Wi-Fi. In one embodiment, the electronic device (101) may decide to perform a handover within the cellular core network while maintaining the Wi-Fi network if the reception signal quality of the Wi-Fi network is good. FIG. 12 is a flowchart illustrating the operation of performing a handover according to one embodiment of the present disclosure. According to the embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0152] Referring to FIG. 12, in operation 1202, an electronic device (101) (e.g., processor (120)) may establish a packet data session (e.g., PDN connection or PDU session) through a first CN node (e.g., ePDG (230) or N3IWF (510)) of a non-cellular access network (e.g., Wi-Fi AP (502)) and a cellular network (e.g., a 3GPP network, an LTE network, or a 5G network). In one embodiment, the electronic device (101) (e.g., processor (120)) may establish the packet data session through the first CN node of the non-cellular access network and the cellular network, or perform a handover from the cellular access network to the non-cellular access network after establishing the packet data session through the cellular access network. When handing over from a cellular access network to a non-cellular access network, the electronic device (101) (e.g., processor (120)) can select and connect to either the ePDG (230) or the N3IWF (510) according to a specified algorithm.

[0153] In one embodiment, the packet data session may include a session for non-IMS services (e.g., a non-IMS PDU session) or a session for IMS services (e.g., an IMS PDU session). In one embodiment, the packet data session may include a PDN connection.

[0154] In operation 1204, the electronic device (101) (e.g., processor (120)) can determine whether the first packet loss rate measured for the packet data session exceeds the first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the first packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and terminate the procedure. If the first packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1206.

[0155] In one embodiment, the first packet loss rate may be determined based on at least one of a DNS (domain name system) packet loss rate, a TCP packet loss rate, a RTP (real-time transport protocol) packet loss rate, or a ping packet loss rate. In one embodiment, an electronic device (101) (e.g., a processor (120)) may transmit DNS packets to a DNS server through the packet data session and measure the packet loss rate (e.g., DNS packet loss rate) for the DNS packets. In one embodiment, an electronic device (101) (e.g., a processor (120)) may transmit TCP packets to an application server through the IMS PDU session while in a call through the IMS PDU session and measure the packet loss rate (e.g., TCP packet loss rate) for the TCP packets. In one embodiment, an electronic device (101) (e.g., a processor (120)) may transmit ping packets to a designated server (e.g., an IMS server) through the packet data session and measure the packet loss rate (e.g., ping packet loss rate) for the ping packets.

[0156] In operation 1206, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate measured for the non-cellular access network exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the non-cellular access network is poor and proceed to operation 1208. If the second packet loss rate does not exceed the second threshold, the electronic device can determine that the communication quality of the non-cellular access network is good and proceed to operation 1210.

[0157] In one embodiment, the second packet loss rate may be measured through a pure Wi-Fi connection (e.g., the second packet data session) connected by the electronic device (101) through a non-cellular access network without passing through a CN node of a cellular network. In one embodiment, the second packet loss rate may be determined based on at least one of a DNS packet loss rate, a TCP packet loss rate, an RTP packet loss rate, or a ping packet loss rate.

[0158] In operation 1208, the electronic device (101) (e.g., processor (120)) may perform a handover from a non-cellular access network to an access network of a cellular network (e.g., eNB (304) or gNB (512)) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) may perform the handover by sending a handover request to the access network of the cellular network. In one embodiment, the electronic device (101) (e.g., processor (120)) may connect to a cellular core network through the access network of the cellular network after the handover.

[0159] In operation 1210, the electronic device (101) (e.g., processor (120)) may perform a handover from a first CN node of a cellular network (e.g., ePDG (230) or N3IWF (510)) to a second CN node of a cellular network (e.g., N3IWF (510) or ePDG (230)) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) may perform the handover by sending a handover request to the first CN node or the second CN node.

[0160] In one embodiment, when the electronic device (101) connects to a non-cellular access network via Wi-Fi, it may establish a pure Wi-Fi connection that connects to a data network (e.g., the Internet) via a Wi-Fi AP (502), and / or establish a non-cellular packet data session that connects to a data network (e.g., the Internet) via a CN node of a cellular network (e.g., an ePDG (230) or an N3IWF (510)). To establish a non-cellular packet data session, the electronic device (101) may select and connect to either the ePDG (230) or the N3IWF (510).

[0161] In one embodiment, since a non-cellular packet data session established via either the ePDG (230) or the N3IWF (510) passes through a cellular network, the electronic device (101) can use services of the cellular network, such as QoS, network slicing, and / or ATSSS, through the non-cellular packet data session. Even after the electronic device (101) handes over the packet data session initially connected through the cellular network to a non-cellular access network, it can be assured of the continuity of services supported on the cellular network via the ePDG (230) or the N3IWF (510).

[0162] FIG. 13 is a diagram illustrating the connectivity of a packet data session according to one embodiment of the present disclosure.

[0163] Referring to FIG. 13, an electronic device (101) (e.g., UE) may include a first application (APP1) (1302), a second application (APP2) (1304), and a selection module (1306). In one embodiment, the selection module (1306) may be a software module or a process. The electronic device (101) may establish at least one non-cellular packet data session (e.g., Session 1 (1308a) and Session 2 (1308b)) for the first application (1302) via a Wi-Fi AP (502), and the selection module (1306) may select whether to use IPSec tunnels connected to an ePDG (230) and a PDN gateway (226) or IPSec tunnels connected to an N3IWF (510) and a UPF (516) for each of Session 1 (1308a) and Session 2 (1308b). In one embodiment, Session 1 (1308a) may be connected to the ePDG (230) via the Wi-Fi AP (502) through IPSec tunnels. In one embodiment, Session 2 (1308b) may be connected to the N3IWF (510) via the Wi-Fi AP (502) through IPSec tunnels. In one embodiment, Session 1 (1308a) and Session 2 (1308b) may be connected to the first application server (APP1 server) (1322) via the data network (1320) (e.g., the Internet).

[0164] In one embodiment, the electronic device (101) may establish a pure Wi-Fi packet data session (e.g., Session 3 (1308c)) for the second application (1304) through a Wi-Fi AP (502). Session 3 (1308c) for the second application (1304) may be connected to the second application server (1312) through at least one network element (e.g., at least one router) (not shown).

[0165] In one embodiment, the electronic device (101) establishes a packet data session (e.g., Session 1 (1308a) or Session 2 (1308b)) for a first application (1302) connected to a first application server (1322) via a cellular access network (e.g., eNB (304) or gNB (512)) and a cellular core network (e.g., PDN gateway (226) or UPF (516)), and may decide to switch the Session 1 (1308a) or Session 2 (1308b) to a non-cellular packet data session when handing over the Session 1 (1308a) or Session 2 (1308b) from the cellular access network to the Wi-Fi AP (502) due to signal quality degradation of the cellular access network or detection of the Wi-Fi AP (502). The electronic device (101) can select either the ePDG (230) or the N3IWF (510) through the selection module (1306) to switch the session 1 (1308a) or session 2 (1308b) to a non-cellular packet data session.

[0166] In one embodiment, the electronic device (101) establishes a packet data session (e.g., session 3 (1308c)) for a second application (1304) connected to a second application server (1312) via a cellular access network (e.g., eNB (304) or gNB (512)) and a cellular core network (e.g., PDN gateway (226) or UPF (516)), and may decide to switch the session 3 (1308c) to a pure Wi-Fi connection when the session 3 (1308c) is handed over from the cellular access network to the Wi-Fi AP (502) due to signal quality degradation of the cellular access network or detection of the Wi-Fi AP (502).

[0167] In one embodiment, the electronic device (101) can determine whether to perform a handover when the quality of experience (QoE) required for a non-cellular packet data session (e.g., a first packet data session) through a non-cellular access network (e.g., Wi-Fi AP (502)) and a cellular core network is not provided (e.g., a decrease in packet loss rate).

[0168] In one embodiment, the electronic device (101) may determine to perform a handover based on the packet loss rate of the first packet data session (e.g., the first packet loss rate). The electronic device (101) may determine to perform a handover if the first packet loss rate is greater than a first threshold. In one embodiment, the electronic device (101) may use the minimum required packet loss rate of the QoS profile specified for the first packet data session as the first threshold.

[0169] In one embodiment, the electronic device (101) may determine to perform a handover for the first packet data session based on a packet data session other than the first packet data session (e.g., a second packet data session). When the electronic device (101) is connecting multiple packet data sessions (e.g., a first packet data session and a second packet data session) through a non-cellular access network (e.g., Wi-Fi), the electronic device (101) may determine to perform a handover for the first packet data session based on the state (e.g., a second packet loss rate) of another packet data session (e.g., a second packet data session) where traffic is occurring. In one embodiment, if there is an IMS PDU session (e.g., a second packet data session) in call, the electronic device (101) may determine to perform a handover for the IMS PDU session (e.g., a first packet data session) based on the RTP packet loss rate of the IMS PDU session. In one embodiment, the electronic device (101) can determine the handover of an IMS PDU session (e.g., a first packet data session) based on the packet loss rate of a non-IMS PDU session (e.g., a second packet data session).

[0170] In one embodiment, the electronic device (101) may determine a handover target (e.g., a cellular access network, or a cellular core network) based on the section where network performance is degraded (e.g., a Wi-Fi section or a backend section). In one embodiment, if the packet loss rate of the pure Wi-Fi connection exceeds a specified threshold (e.g., a second threshold), the electronic device (101) may determine that there is a problem with the Wi-Fi section and perform a handover from the non-cellular access network to the cellular access network. In one embodiment, if the packet loss rate of the pure Wi-Fi connection does not exceed the second threshold, the electronic device (101) may determine that there is a problem with the backend network (e.g., a cellular core network) and perform a handover from the first CN node (e.g., N3IWF or ePDG) of the cellular network to the second CN node (e.g., ePDG or N3IWF) while maintaining the non-cellular access network.

[0171] In one embodiment, the electronic device (101) may identify a QoS profile for QoS flows supported by a non-cellular packet data session and determine a threshold value (e.g., a first threshold value) for determining a handover of the non-cellular packet data session based on a packet loss rate parameter (e.g., minimum required packet loss rate) indicated by the QoS profile. In one embodiment, if the non-cellular packet data session supports QCI 1 and 2 among the guaranteed bit rate (GBR) profiles of an LTE network, the electronic device (101) may set the first threshold value (e.g., PACKET_LOSS_RATE_TH_NON_IMS) to MIN(10 -2 , 10 -3 It can be decided as ).

[0172] [Table 5] below shows examples of minimum required packet loss rates according to QCI.

[0173] QCI Resource Type Priority Level Packet Delay Budget Minimum Required Packet Loss Rate Example Services 1GBR 2100 ms 10 -2 Voice call (conversational voice) 24150 ms10 -3 Video call (conversational video) (e.g., live streaming) 3350 ms 10 -3 Real-time gaming, V2X Message 45300 ms10 -6 Non-conversational video (e.g., buffering streaming)

[0174] FIG. 14 is a diagram illustrating a handover determination for packet loss occurrence intervals according to an embodiment of the present disclosure. Referring to FIG. 14, when the first packet loss rate of a non-cellular packet data session is greater than a first threshold and the second packet loss rate of a pure Wi-Fi connection is greater than a second threshold, the electronic device (101) determines that there is a network problem within the non-cellular interval (1402) between the electronic device (101) and the Wi-Fi AP (502), and can perform a handover from the Wi-Fi AP (502) to a cellular access network (e.g., eNB (304) or gNB (512)). If the electronic device (101) determines that there is a network problem within the backend section (1404) between the Wi-Fi AP (502) and the application server (e.g., the first application server (1322)) when the first packet loss rate of the non-cellular packet data session is greater than the first threshold but the second packet loss rate of the pure Wi-Fi connection is not greater than the second threshold, it can perform a handover between the ePDG (230) and the N3IWF (510).

[0175] FIG. 15 is a flowchart illustrating a procedure for handing over from N3IWF (510) to ePDG (230) according to one embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0176] Referring to FIG. 15, in operation 1502, an electronic device (101) (e.g., processor (120)) can establish a packet data session (e.g., a non-IMS PDU session) through a Wi-Fi AP (e.g., Wi-Fi AP (502)) and an N3IWF (510). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the non-IMS PDU session anew through the Wi-Fi AP (502) and the N3IWF (510), or hand over the non-IMS PDU session established through the gNB (512) to the Wi-Fi AP (502) so that the non-IMS PDU session is connected via the N3IWF (510). In one embodiment, an electronic device (101) (e.g., a processor (120)) can establish the non-IMS PDU session for a first application (e.g., a first application (1302)).

[0177] In operation 1504, the electronic device (101) (e.g., processor (120)) can collect network metrics of the pure Wi-Fi. In one embodiment, the electronic device (101) (e.g., processor (120)) can identify that a PDU session (e.g., session 3 (1308c)) connected via the Wi-Fi AP (502) is connected without passing through a cellular core network (e.g., 5GC) and can collect network metrics of the pure Wi-Fi from said session 3 (1308c). In one embodiment, the network metrics of the pure Wi-Fi may include the Wi-Fi packet loss rate (e.g., second packet loss rate).

[0178] In operation 1506, the electronic device (101) (e.g., processor (120)) can collect network metrics of the non-IMS PDU session. In one embodiment, the network metrics of the non-IMS PDU session may include the packet loss rate of the non-IMS PDU session (e.g., a first packet loss rate) (e.g., at least one of a DNS packet loss rate, a TCP packet loss rate, an RTP packet loss rate, or a ping packet loss rate).

[0179] In operation 1508, the electronic device (101) (e.g., processor (120)) can determine whether the first packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the first packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 1504 or terminate the procedure. If the first packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1510.

[0180] In operation 1510, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 1512. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 1514.

[0181] In operation 1512, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and N3IWF (510) to a cellular network (e.g., gNB (512) and UPF (516)) for the non-IMS PDU session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the gNB (512).

[0182] In operation 1514, the electronic device (101) (e.g., processor (120)) can perform a handover from the N3IWF (510) to the ePDG (230) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., ePDG (230)) through a Wi-Fi AP (502).

[0183] FIG. 16 is a flowchart illustrating a procedure for handing over from ePDG (230) to N3IWF (510) according to one embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0184] Referring to FIG. 16, in operation 1602, an electronic device (101) (e.g., processor (120)) can establish a packet data session (e.g., a non-IMS PDU session) through a Wi-Fi AP (e.g., Wi-Fi AP (502)) and an ePDG (230). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the non-IMS PDU session anew through the Wi-Fi AP (502) and an N3IWF (510), or hand over a non-IMS PDU session established through an eNB (304) to the Wi-Fi AP (502) so that the non-IMS PDU session is connected via the ePDG (230). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the non-IMS PDU session for a first application (e.g., first application (1302)).

[0185] In operation 1604, the electronic device (101) (e.g., processor (120)) can collect network metrics of the pure Wi-Fi. In one embodiment, the electronic device (101) (e.g., processor (120)) can identify that a PDU session (e.g., session 3 (1308c)) connected via the Wi-Fi AP (502) is connected without passing through a cellular core network (e.g., EPC) and can collect network metrics of the pure Wi-Fi from said session 3 (1308c). In one embodiment, the network metrics of the pure Wi-Fi may include the Wi-Fi packet loss rate (e.g., second packet loss rate).

[0186] In operation 1606, the electronic device (101) (e.g., processor (120)) can collect network metrics of the non-IMS PDU session. In one embodiment, the network metrics of the non-IMS PDU session may include the packet loss rate of the non-IMS PDU session (e.g., a first packet loss rate) (e.g., at least one of a DNS packet loss rate, a TCP packet loss rate, an RTP packet loss rate, or a ping packet loss rate).

[0187] In operation 1608, the electronic device (101) (e.g., processor (120)) can determine whether the first packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the first packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 1604 or terminate the procedure. If the first packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1610.

[0188] In operation 1610, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 1612. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 1514.

[0189] In operation 1612, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and ePDG (230) to a cellular network (e.g., eNB (304) and PDN gateway (226)) for the non-IMS PDU session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the eNB (304).

[0190] In operation 1614, the electronic device (101) (e.g., processor (120)) can perform a handover from the ePDG (230) to the N3IWF (510) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., N3IWF (510)) via a Wi-Fi AP (502).

[0191] In one embodiment, the electronic device (101) may perform a handover from the N3IWF (510) to the ePDG (230) and, while connecting a non-IMS PDU session through the ePDG (230), if the first packet loss rate of the non-IMS PDU session exceeds a first threshold, it may not perform a handover to the N3IWF (510) again, but instead perform a handover from the Wi-Fi AP (502) to a cellular access network (e.g., eNB (304)).

[0192] In one embodiment, the electronic device (101) may perform a handover from the ePDG (230) to the N3IWF (620) when, while connecting a non-IMS PDU session through the ePDG (230) after handing over from the N3IWF (510) to the ePDG (230), the first packet loss rate of the non-IMS PDU session exceeds a first threshold.

[0193] FIG. 17 is a flowchart illustrating a communication procedure following a handover to an ePDG (230) according to one embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0194] Referring to FIG. 17, in operation 1702, the electronic device (101) (e.g., processor (120)) can hand over a packet data session (e.g., a non-IMS PDU session) from the N3IWF (510) to the ePDG (230). In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover from the N3IWF (510) to the ePDG (230) through the procedure of FIG. 15 (e.g., operation 1514).

[0195] In operation 1704, the electronic device (101) (e.g., processor (120)) can collect network metrics of the pure Wi-Fi. In one embodiment, the electronic device (101) (e.g., processor (120)) can collect network metrics of the pure Wi-Fi from a PDU session (e.g., session 3 (1308c)) connected through the Wi-Fi AP (502) without passing through a cellular core network (e.g., EPC), rather than the non-IMS PDU session. In one embodiment, the network metrics of the pure Wi-Fi may include the Wi-Fi packet loss rate (e.g., second packet loss rate).

[0196] In operation 1706, the electronic device (101) (e.g., processor (120)) can collect network metrics of the non-IMS PDU session. In one embodiment, the network metrics of the non-IMS PDU session may include the packet loss rate of the non-IMS PDU session (e.g., a first packet loss rate) (e.g., at least one of a DNS packet loss rate, a TCP packet loss rate, an RTP packet loss rate, or a ping packet loss rate).

[0197] In operation 1708, the electronic device (101) (e.g., processor (120)) can determine whether the first packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the first packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 1704 or terminate the procedure. If the first packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1710.

[0198] In operation 1710, the electronic device (101) (e.g., processor (120)) can perform a handover from a non-cellular access network to an access network of a cellular network (e.g., eNB (304)) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the cellular access network (e.g., eNB (304)). In one embodiment, the electronic device (101) (e.g., processor (120)) can connect to a cellular core network (e.g., PDN gateway (226)) through the access network of the cellular network after the handover.

[0199] FIG. 17 illustrates the procedure following the handover from the N3IWF (510) to the ePDG (230), but similar operations may be performed after the handover from the ePDG (230) to the N3IWF (510). In one embodiment, the electronic device (101) may perform a handover to the ePDG (230) again, or perform a handover from the Wi-Fi AP (502) to a cellular access network (e.g., gNB (512)) without handing over to the ePDG (230) if the first packet loss rate of a non-IMS PDU session connected through the N3IWF (510) exceeds a first threshold after handing over from the ePDG (230) to the N3IWF (510).

[0200] In one embodiment, the first packet loss rate of a non-IMS PDU session may include either or both of the DNS packet loss rate or the TCP packet loss rate. The TCP packet loss rate may represent the packet loss rate to the application server (e.g., the first application server (1322)). The DNS packet loss rate may represent the packet loss rate to the DNS server. In one embodiment, the electronic device (101) may determine that a handover is required due to a problem in the backend network if both the DNS packet loss rate and the TCP packet loss rate are greater than the first threshold.

[0201] FIG. 18a is a flowchart illustrating a handover procedure based on TCP packet loss rate and DNS packet loss rate according to an embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0202] Referring to FIG. 18a, in operation 1802, an electronic device (101) (e.g., processor (120)) can establish a packet data session (e.g., a non-IMS PDU session) through a Wi-Fi AP (e.g., Wi-Fi AP (502)) and an N3IWF (510). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the non-IMS PDU session anew through the Wi-Fi AP (502) and the N3IWF (510), or allow the non-IMS PDU session established through the gNB (512) to be connected via the N3IWF (510) while handing over the Wi-Fi AP (502) to the non-IMS PDU session. In one embodiment, an electronic device (101) (e.g., a processor (120)) can establish the non-IMS PDU session for a first application (e.g., a first application (1302)).

[0203] In operation 1804, the electronic device (101) (e.g., processor (120)) can collect network metrics of the pure Wi-Fi. In one embodiment, the electronic device (101) (e.g., processor (120)) can identify that a PDU session (e.g., session 3 (1308c)) connected via the Wi-Fi AP (502) is connected without passing through a cellular core network (e.g., 5GC) and can collect network metrics of the pure Wi-Fi from said session 3 (1308c). In one embodiment, the network metrics of the pure Wi-Fi may include the Wi-Fi packet loss rate (e.g., second packet loss rate).

[0204] In operation 1806, the electronic device (101) (e.g., processor (120)) can collect network metrics of the non-IMS PDU session. In one embodiment, the network metrics of the non-IMS PDU session may include DNS packet loss rates and TCP packet loss rates measured through the non-IMS PDU session.

[0205] In operation 1808, the electronic device (101) (e.g., processor (120)) can determine whether the TCP packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the TCP packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 1804 or terminate the procedure. If the TCP packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1810.

[0206] In operation 1810, the electronic device (101) (e.g., processor (120)) can determine whether the DNS packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the DNS packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 1804 or terminate the procedure. If the DNS packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1812.

[0207] In operation 1812, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 1814. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 1816.

[0208] In operation 1814, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and N3IWF (510) to a cellular network (e.g., gNB (512) and UPF (516)) for the non-IMS PDU session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the gNB (512).

[0209] In operation 1816, the electronic device (101) (e.g., processor (120)) can perform a handover from the N3IWF (510) to the ePDG (230) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., ePDG (230)) via a Wi-Fi AP (502).

[0210] FIG. 18b is a flowchart illustrating a handover procedure based on a TCP packet loss rate or a DNS packet loss rate according to an embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0211] Referring to FIG. 18b, in operation 1822, an electronic device (101) (e.g., processor (120)) can establish a packet data session (e.g., a non-IMS PDU session) through a Wi-Fi AP (e.g., Wi-Fi AP (502)) and an N3IWF (510). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the non-IMS PDU session anew through the Wi-Fi AP (502) and the N3IWF (510), or allow the non-IMS PDU session established through the gNB (512) to be connected via the N3IWF (510) while handing over the non-IMS PDU session established through the gNB (512) to the Wi-Fi AP (502). In one embodiment, an electronic device (101) (e.g., a processor (120)) can establish the non-IMS PDU session for a first application (e.g., a first application (1302)).

[0212] In operation 1824, the electronic device (101) (e.g., processor (120)) can collect network metrics of the pure Wi-Fi. In one embodiment, the electronic device (101) (e.g., processor (120)) can identify that a PDU session (e.g., session 3 (1308c)) connected via the Wi-Fi AP (502) is connected without passing through a cellular core network (e.g., 5GC) and can collect network metrics of the pure Wi-Fi from said session 3 (1308c). In one embodiment, the network metrics of the pure Wi-Fi may include the Wi-Fi packet loss rate (e.g., second packet loss rate).

[0213] In operation 1826, the electronic device (101) (e.g., processor (120)) can collect network metrics of the non-IMS PDU session. In one embodiment, the network metrics of the non-IMS PDU session may include DNS packet loss rates and TCP packet loss rates measured through the non-IMS PDU session.

[0214] In operation 1828, the electronic device (101) (e.g., processor (120)) can determine whether the TCP packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS) or whether the DNS packet loss rate of the non-IMS PDU session exceeds a first threshold (TH1) (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the TCP packet loss rate does not exceed the first threshold and the DNS packet loss rate does not exceed the first threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 1824 or terminate the procedure. If the TCP packet loss rate exceeds the first threshold or the DNS packet loss rate exceeds the first threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 1830.

[0215] In operation 1830, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 1832. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 1834.

[0216] In operation 1832, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and N3IWF (510) to a cellular network (e.g., gNB (512) and UPF (516)) for the non-IMS PDU session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the gNB (512).

[0217] In operation 1834, the electronic device (101) (e.g., processor (120)) can perform a handover from the N3IWF (510) to the ePDG (230) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., ePDG (230)) via a Wi-Fi AP (502).

[0218] In one embodiment, the electronic device (101) may determine whether to hand over the non-IMS PDU session based on the RTP packet loss rate of the IMS PDU session instead of using the first packet loss rate measured for the non-IMS PDU session. Since the RTP packet loss rate represents the end-to-end packet loss rate between the electronic device (101) and the call partner, the electronic device (101) may evaluate the quality of the non-IMS PDU session through a separate ping test.

[0219] FIG. 19 is a drawing for illustrating a ping test according to one embodiment of the present disclosure.

[0220] Referring to FIG. 19, an electronic device (101) (e.g., UE) may include a first application (APP1) (1902), a call application (1904), a handover management module (1906), and an IMS management module (1908). In one embodiment, at least one of the handover management module (1906) or the IMS management module (1908) may be a software module or process executable by a processor (e.g., processor (120)).

[0221] In one embodiment, the electronic device (101) may be connected to a UPF (516a) via a wireless access network (RAN) (1910) (e.g., gNB (512)) or to an ePDG (230) / PDN gateway (226) or N3IWF (510) / UPF (516b, 516c) via a Wi-Fi AP (502).

[0222] In one embodiment, the electronic device (101) may connect a non-IMS PDU session (1910a) for a first application (1902) to a data network 1 (1920) (e.g., the Internet) via a Wi-Fi AP (502) and an N3IWF (510). In one embodiment, the non-IMS PDU session (1910a) may be connected to a first application server (APP1 server) (1922) via the data network 1 (1920). In one embodiment, the electronic device (101) may connect an IMS PDU session (1910b) for a second application (e.g., a call application (1904)) to a data network 2 (1924) (e.g., the Internet) via a Wi-Fi AP (502) and an N3IWF (510). In one embodiment, the IMS PDU session (1910b) may be connected to an IMS server (1926) via the data network 2 (1924). In one embodiment, the electronic device (101) can manage an IMS PDU session (1910b) through an IMS management module (1908).

[0223] In one embodiment, the electronic device (101) can hand over a non-IMS session (1910a) to the ePDG (230) or to the wireless access network (1910) via a handover management module (1906). In one embodiment, the handover management module (1906) can collect RTP metrics (e.g., RTP packet loss rate) for an IMS PDU session (1910b) from an IMS management module (1908). In one embodiment, the handover management module (1906) can collect the ping packet loss rate through a ping test for the non-IMS PDU session (1910a). In one embodiment, the handover management module (1906) can trigger the handover of the non-IMS session (1910a) to the ePDG (230) or to the wireless access network (1910) based on the RTP packet loss rate and the packet loss rate from the ping test.

[0224] FIG. 20 is a flowchart illustrating a handover procedure based on RTP packet loss rate and ping packet loss rate according to an embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0225] Referring to FIG. 20, in operation 2002, an electronic device (101) (e.g., a processor (120)) can establish a packet data session (e.g., a non-IMS PDU session (1910a)) through a Wi-Fi AP (e.g., a Wi-Fi AP (502)) and an N3IWF (510). In one embodiment, the electronic device (101) (e.g., a processor (120)) can establish the non-IMS PDU session (1910a) anew through the Wi-Fi AP (502) and the N3IWF (510), or allow the non-IMS PDU session (1910a) established through the gNB (512) to be connected via the N3IWF (510) while handing over the Wi-Fi AP (502) to the non-IMS PDU session (1910a). In one embodiment, an electronic device (101) (e.g., a processor (120)) can establish the non-IMS PDU session for a first application (e.g., a first application (1902)).

[0226] In operation 2004, an electronic device (101) (e.g., a processor (120)) can collect network metrics of an IMS PDU session (1910b). In one embodiment, the electronic device (101) (e.g., a processor (120)) can identify that the IMS PDU session (1910b) is connected via a Wi-Fi AP (502) and an N3IWF (510) for a call application (1904) and can collect network metrics of the IMS PDU session (1910b). In one embodiment, the network metrics of the IMS PDU session (1910b) may include the RTP packet loss rate measured through the IMS PDU session (1910b).

[0227] In operation 2006, the electronic device (101) (e.g., processor (120)) can determine whether the RTP packet loss rate of the IMS PDU session (1910b) exceeds a specified threshold (e.g., PACKET_LOSS_RATE_TH_RTP). If the RTP packet loss rate does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 2004 or terminate the procedure. If the RTP packet loss rate exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2008.

[0228] In operation 2008, the electronic device (101) (e.g., processor (120)) may collect network metrics of a non-IMS PDU session through a ping test. In one embodiment, the network metrics of the non-IMS PDU session may include the ping packet loss rate collected through the ping test. Although operation 2008 is depicted as being performed after operation 2006, the electronic device (101) (e.g., processor (120)) may perform operation 2008 at any time before operation 2010.

[0229] In operation 2010, the electronic device (101) (e.g., processor (120)) can determine whether the ping packet loss rate of the non-IMS PDU session exceeds a specified threshold (e.g., PACKET_LOSS_RATE_TH_PING). If the ping packet loss rate does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 2004 or terminate the procedure. If the ping packet loss rate exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2012.

[0230] In operation 2012, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 2014. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 2016.

[0231] In operation 2014, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and N3IWF (510) to a cellular network (e.g., gNB (512) and UPF (516)) for the non-IMS PDU session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the gNB (512).

[0232] In operation 2016, the electronic device (101) (e.g., processor (120)) can perform a handover from the N3IWF (510) to the ePDG (230) for the packet data session. In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., ePDG (230)) through a Wi-Fi AP (502).

[0233] In one embodiment, when an IMS PDU session connected to an electronic device (101) is not being used for a call, the electronic device (101) may determine a handover of the IMS PDU session based on the packet loss rate of the non-IMS PDU session. In one embodiment, the electronic device (101) may determine a handover of the IMS PDU session based on the packet loss rate of the non-IMS PDU session and the ping packet loss rate of the IMS PDU session.

[0234] FIG. 21 is a flowchart illustrating a handover procedure based on the packet loss rate and ping packet loss rate of another PDU session according to one embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0235] Referring to FIG. 21, in operation 2102, an electronic device (101) (e.g., processor (120)) can establish a packet data session (e.g., IMS PDU session (1910b)) through a Wi-Fi AP (e.g., Wi-Fi AP (502)) and an N3IWF (510). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the IMS PDU session (1910b) anew through the Wi-Fi AP (502) and the N3IWF (510), or allow the IMS PDU session (1910b) established through the gNB (512) to be connected via the N3IWF (510) while handing over the Wi-Fi AP (502) to the IMS PDU session (1910b).

[0236] In operation 2104, an electronic device (101) (e.g., a processor (120)) can obtain the reception signal quality (e.g., RSSI) of a Wi-Fi network (e.g., a Wi-Fi AP (502)). In one embodiment, the electronic device (101) (e.g., a processor (120)) can evaluate the RSSI of the Wi-Fi network (e.g., Wi-Fi RSSI) based on identifying that an IMS PDU session (1910b) is not being used for a call.

[0237] In operation 2106, the electronic device (101) (e.g., processor (120)) can determine whether the Wi-Fi RSSI exceeds a specified threshold (e.g., WIFI_ROVEOUT_TH). If the Wi-Fi RSSI does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2108 to perform a legacy handover according to the conventional method, or determine that a handover is unnecessary and terminate the procedure. If the Wi-Fi RSSI exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2110.

[0238] In operation 2110, the electronic device (101) (e.g., processor (120)) can collect network metrics of a non-IMS PDU session (e.g., non-IMS PDU session (1910a)). In one embodiment, the electronic device (101) (e.g., processor (120)) can collect network metrics of a non-IMS PDU session (1910a) based on identifying that, in addition to the IMS PDU session (1910b), there exists a non-IMS PDU session (1910b) connected via a Wi-Fi AP (502) and an N3IWF (510). Network metrics of a non-IMS PDU session (1910a) may include packet loss rates (e.g., DNS packet loss rates and / or TCP packet loss rates) measured through the non-IMS PDU session (1910a).

[0239] In operation 2112, the electronic device (101) (e.g., processor (120)) can determine whether the packet loss rate of the non-IMS PDU session (1910a) exceeds a specified threshold (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the packet loss rate of the non-IMS PDU session (1910a) does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 2104 or terminate the procedure. If the packet loss rate of the non-IMS PDU session (1910a) exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2114.

[0240] In operation 2114, the electronic device (101) (e.g., processor (120)) may collect network metrics of the IMS PDU session (1910b). In one embodiment, the network metrics of the IMS PDU session (1910b) may include ping packet loss rates collected through ping tests. Although operation 2114 is shown here as being performed after operation 2112, the electronic device (101) (e.g., processor (120)) may perform operation 2114 at any time before operation 2116.

[0241] In operation 2116, the electronic device (101) (e.g., processor (120)) can determine whether the ping packet loss rate of the IMS PDU session (1910b) exceeds a specified threshold (e.g., PACKET_LOSS_RATE_TH_PING). If the ping packet loss rate does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 2104 or terminate the procedure. If the ping packet loss rate exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2118.

[0242] In operation 2118, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 2120. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 2122.

[0243] In operation 2120, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and N3IWF (510) to a cellular network (e.g., gNB (512) and UPF (516)) for the IMS PDU session (1910b). In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the gNB (512).

[0244] In operation 2122, the electronic device (101) (e.g., processor (120)) can perform a handover from the N3IWF (510) to the ePDG (230) for the IMS PDU session (1910b). In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., ePDG (230)) via a Wi-Fi AP (502).

[0245] FIG. 22 is a flowchart illustrating a handover procedure based on the packet loss rate and ping packet loss rate of another PDU session according to one embodiment of the present disclosure. According to embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order. In one embodiment, at least one of the operations described below may be executed by a processor (e.g., processor (120) of FIG. 1) of an electronic device (200) (e.g., electronic device (101) of FIG. 1). In one embodiment, a memory of the electronic device (200) (e.g., memory (130) of FIG. 1) may store instructions that cause the electronic device (200) to operate according to at least one of the operations described below.

[0246] Referring to FIG. 22, in operation 2202, an electronic device (101) (e.g., processor (120)) can establish a packet data session (e.g., IMS PDU session (1910b)) through a Wi-Fi AP (e.g., Wi-Fi AP (502)) and an ePDG (230). In one embodiment, the electronic device (101) (e.g., processor (120)) can establish the IMS PDU session (1910b) anew through the Wi-Fi AP (502) and the ePDG (230), or allow the IMS PDU session (1910b) established through the eNB (304) to be connected via the ePDG (230) while handing over the Wi-Fi AP (502) to the IMS PDU session (1910b).

[0247] In operation 2204, an electronic device (101) (e.g., a processor (120)) can obtain the reception signal quality (e.g., RSSI) of a Wi-Fi network (e.g., a Wi-Fi AP (502)). In one embodiment, the electronic device (101) (e.g., a processor (120)) can evaluate the RSSI of the Wi-Fi network (e.g., a Wi-Fi RSSI) based on identifying that an IMS PDU session (1910b) is not being used for a call.

[0248] In operation 2206, the electronic device (101) (e.g., processor (120)) can determine whether the Wi-Fi RSSI exceeds a specified threshold (e.g., WIFI_ROVEOUT_TH). If the Wi-Fi RSSI does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2208 to perform a legacy handover according to the conventional method, or determine that a handover is unnecessary and terminate the procedure. If the Wi-Fi RSSI exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2210.

[0249] In operation 2210, the electronic device (101) (e.g., processor (120)) can collect network metrics of a non-IMS PDU session. In one embodiment, the electronic device (101) (e.g., processor (120)) can collect network metrics of the non-IMS PDU session based on identifying that, in addition to the IMS PDU session (1910b), there exists a non-IMS PDU session connected via the Wi-Fi AP (502) and ePDG (230). The network metrics of the non-IMS PDU session may include packet loss rates (e.g., DNS packet loss rates and / or TCP packet loss rates) measured through the non-IMS PDU session.

[0250] In operation 2212, the electronic device (101) (e.g., processor (120)) can determine whether the packet loss rate of the non-IMS PDU session exceeds a specified threshold (e.g., PACKET_LOSS_RATE_TH_NON_IMS). If the packet loss rate of the non-IMS PDU session does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 2204 or terminate the procedure. If the packet loss rate of the non-IMS PDU session exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2214.

[0251] In operation 2214, the electronic device (101) (e.g., processor (120)) may collect network metrics of the IMS PDU session (1910b). In one embodiment, the network metrics of the IMS PDU session (1910b) may include ping packet loss rates collected through ping tests. Although operation 2214 is shown here as being performed after operation 2212, the electronic device (101) (e.g., processor (120)) may perform operation 2214 at any time before operation 2216.

[0252] In operation 2216, the electronic device (101) (e.g., processor (120)) can determine whether the ping packet loss rate of the IMS PDU session (1910b) exceeds a specified threshold (e.g., PACKET_LOSS_RATE_TH_PING). If the ping packet loss rate does not exceed the threshold, the electronic device (101) (e.g., processor (120)) can determine that a handover is unnecessary and return to operation 2204 or terminate the procedure. If the ping packet loss rate exceeds the threshold, the electronic device (101) (e.g., processor (120)) can proceed to operation 2218.

[0253] In operation 2218, the electronic device (101) (e.g., processor (120)) can determine whether the second packet loss rate of pure Wi-Fi exceeds a second threshold (TH2) (e.g., PACKET_LOSS_RATE_TH_PURE_WIFI). If the second packet loss rate exceeds the second threshold, the electronic device (101) (e.g., processor (120)) can determine that the communication quality of the Wi-Fi AP (502) is poor and proceed to operation 2220. If the second packet loss rate does not exceed the second threshold, the communication quality of the Wi-Fi AP (502) can determine that the communication quality of the Wi-Fi AP (502) is good and proceed to operation 2222.

[0254] In operation 2220, the electronic device (101) (e.g., processor (120)) can perform a handover from the Wi-Fi AP (502) and ePDG (230) to a cellular network (e.g., eNB (304) and packet gateway (306)) for the IMS PDU session (1910b). In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to the eNB (304).

[0255] In operation 2222, the electronic device (101) (e.g., processor (120)) can perform a handover from the ePDG (230) to the N3IWF (510) for the IMS PDU session (1910b). In one embodiment, the electronic device (101) (e.g., processor (120)) can perform the handover by sending a handover request to a cellular core network (e.g., N3IWF (510)) via a Wi-Fi AP (502).

[0256] FIG. 23 is a block diagram showing the configuration of an electronic device according to one embodiment of the present disclosure.

[0257] Referring to FIG. 23, an electronic device (101) (e.g., UE) may include at least one of an IMS service module (2302), a network metric manager module (2304), a non-cellular handover manager module (2306), a telephony manager module (2316), a radio interface layer (RIL) (2324), an IPSec management module (2326), a kernel (2328), a cellular modem (2330), or a Wi-Fi communication circuit (2332). At least one of the above components may be composed of software, a process, hardware, or firmware.

[0258] In one embodiment, the IMS service module (2302) includes an IMS stack and can perform IMS-related operations by supporting SIP and / or RTP.

[0259] In one embodiment, a network metric management module (2304) may collect and manage network-related information (e.g., network metrics) from a kernel (2308) or an operating system (OS) framework (not shown). The network metrics may include TCP statistics (e.g., at least one of a TCP connection error rate, a TCP packet error rate, a total lost, or a round trip time (RTT)), and / or DNS statistics (e.g., DNS RTT, and / or DNS packet error rate).

[0260] In one embodiment, the non-cellular handover management module (2306) may include at least one of a handover event receiver module (2308), a handover decision maker module (2310), a handover stats tracker module (2312), or a ping checker module (2314) to manage handovers of a non-cellular access network (e.g., a non-3GPP access network).

[0261] In one embodiment, the handover stat tracking module (2312) receives network metrics from the IMS service module (2302) and / or the network metric management module (2304) and can manage the received information. Network metrics received from the IMS service module (2302) may include calling status and / or RTP packet loss rate. Network metrics received from the network metric management module (2304) may include DNS packet loss rate, TCP connection error information, TCP packet loss rate (e.g., average loss rate), and / or TCP packet total lost information.

[0262] In one embodiment, the handover decision module (2310) may receive network metrics from the handover stat tracking module (2312) and determine a handover based on the network metrics. When the handover decision module (2310) determines a handover, it may send a handover request to the call management module (2316). The handover decision module (2310) may request a ping test from the ping test module (2314). When a ping test is requested, the handover decision module (2310) may provide gateway information assigned to a packet data session (e.g., a PDU session) to the ping test module (2314).

[0263] In one embodiment, the ping test module (2314) may receive a ping test request from the handover decision module (2310) and perform a ping test. The ping test may be performed using ICMP (Internet Control Message Protocol), DNS request / response, and / or TCP synchronization / ac. The ping test module (2314) may receive information about the target server (e.g., IMS server) for which the ping test is being performed from the handover event receiving module (2308). The ping test module (2314) may measure the packet loss rate of the ping packets by sending ping packets (e.g., ICMP request message, DNS request message, or TCP synchronization message) to the server indicated by the handover event receiving module (2308) and receiving a response from the server.

[0264] In one embodiment, the handover event receiving module (2308) may receive a handover result from the call management module (2316). The handover result may include information about the handovered PDU session (e.g., at least one of an IP address, DNS information, gateway address, access network type, or non-3GPP access network type).

[0265] In one embodiment, the call management module (2316) may include at least one of an access network (AN) manager module (2318), a cellular access network connection management module (2320), or a non-cellular access network connection management module (2322). The access network connection management module (2318) manages the connection status to the access network and can perform a handover at the request of the non-cellular access network connection management module (2322). The cellular access network connection management module (2320) can manage a connection with the cellular access network (e.g., an LTE wireless connection or a 5G wireless connection). The non-cellular access network connection management module (2322) can manage a connection between the non-cellular access network and a cellular core network (e.g., an N3IWF (510) or an ePDG (230)).

[0266] In one embodiment, the RIL (2324) may provide an interface for controlling the cellular modem (2330). In one embodiment, the IPSec management module (2326) may manage IPSec connections for connection with the N3IWF (510) or ePDG (230). Although not illustrated, the electronic device (101) may further include a NAS signaling module for communication with the N3IWF (510).

[0267] In one embodiment, the cellular modem (2330) may perform a connection procedure with a cellular access network (e.g., eNB (304) or gNB (512)) or disconnect from the cellular access network under the control of the cellular access network connection management module (2320). In one embodiment, the Wi-Fi communication circuit (2332) may perform a connection procedure with a non-cellular access network (e.g., Wi-Fi AP (502)) or disconnect from the non-cellular access network under the control of the non-cellular access network connection management module (2322).

[0268] FIG. 24 is a sequence diagram illustrating a handover procedure according to one embodiment of the present disclosure. Depending on the embodiments, at least one of the operations described below may be omitted, modified, or executed in a different order.

[0269] Referring to FIG. 24, in operation 2402, the IMS service module (2302) may transmit a notification message to the handover stat tracking module (2312) containing a calling state and / or a packet error rate (e.g., a packet error rate of an IMS PDU session). In one embodiment, the IMS service module (2302) may transmit the notification message periodically or upon request. In operation 2404, the network metric management module (2304) may transmit a notification message to the handover stat tracking module (2312) containing a packet error rate (e.g., a packet error rate of a non-IMS PDU session and a pure Wi-Fi packet error rate). In one embodiment, the network metric management module (2304) may transmit the notification message periodically or upon request.

[0270] In operation 2406, the handover stat tracking module (2312) can send a metric notification (e.g., notifyMetric()) message to the handover decision module (2310) containing network metrics collected from the IMS service module (2302) and the network metric management module (2304) (e.g., packet error rate of an IMS PDU session, packet error rate of a non-IMS PDU session, and / or pure Wi-Fi packet error rate).

[0271] In one embodiment, the handover determination module (2310) may perform operations 2408 and 2410 based on determining that a ping test is necessary to determine the handover. In operation 2410, the handover determination module (2310) may send a ping test request (e.g., requestPingCheck()) message containing gateway information and PDU session information to the ping test module (2314). Based on the ping test request message, the ping test module (2314) may measure the packet loss rate of the ping packets (e.g., ping packet loss rate) by sending ping packets to a designated server (e.g., IMS server) and receiving a response. In operation 2410, the ping test module (2314) may send a ping result (e.g., onPingResult()) message containing the ping packet loss rate to the handover determination module (2310).

[0272] In operation 2412, the handover decision module (2310) may determine whether to perform a handover for a packet data session (e.g., a non-IMS PDU session or an IMS PDU session) connected through a non-cellular access network and a cellular core network, based on the network metric and / or the ping packet loss rate. In one embodiment, the handover decision module (2310) may perform any one of the procedures of FIG. 12, FIG. 15, FIG. 16, FIG. 17, FIG. 18, FIG. 20, FIG. 21, or FIG. 22. The handover decision module (2310) may proceed to operation 2414 based on the determination to perform a handover.

[0273] In operation 2414, the handover decision module (2310) may transmit a handover request (e.g., requesthandover()) message to the call management module (2316), which includes current PDU session information indicating the PDU session to be handed over, and / or information indicating the target access network to be handed over. Based on the handover request message, the call management module (2316) may perform a handover from a non-cellular access network (e.g., Wi-Fi AP (502)) to a cellular access network (e.g., eNB (304) or gNB (512)), or perform a handover between CN nodes (e.g., ePDG (230) and N3IWF (510)) within a cellular core network.

[0274] In operation 2416, the call management module (2316) can send a handover result (e.g., onHandoverResult()) message containing information indicating handover success or failure, IP address, gateway information, and / or DNS information to the handover event receiving module (2308).

[0275] According to embodiments of the present disclosure, the electronic device (101) can determine a handover using the packet loss rate as well as the signal strength of the access network, and can dynamically adjust the handover threshold by determining the threshold that serves as the criterion for the handover as the minimum required packet loss rate indicated by the QoS profile. According to embodiments of the present disclosure, the electronic device (101) can determine a handover using not only the packet data session to be handed over, but also other packet data sessions (e.g., a session of a pure Wi-Fi connection, a non-IMS PDU session, or an IMS PDU session). For example, the electronic device (101) can determine whether to hand over a non-IMS PDU session based on the network metric (e.g., packet loss rate) of the IMS PDU session. For example, the electronic device (101) can determine whether to hand over an IMS PDU session based on the network metric (e.g., packet loss rate) of the non-IMS PDU session.

[0276] Embodiments of the present disclosure can enable efficient use of network resources by supporting handover from N3IWF (510) to ePDG (230) or from ePDG (230) to N3IWF (510) depending on network segments where packet loss occurs. Embodiments of the present disclosure can improve the user's network usage experience by using network metrics of other PDU sessions to determine the handover of a PDU session.

[0277] An electronic device (101) according to one embodiment of the present disclosure may include a communication circuit (192), at least one processor (120), and a memory (130) for storing instructions. When the instructions are executed individually or collectively by the at least one processor, the electronic device may establish a packet data session through the communication circuit via a first CN (core network) node of a non-cellular access network and a cellular network. When the instructions are executed individually or collectively by the at least one processor, the electronic device may determine whether a first packet loss rate associated with the packet data session exceeds a first threshold. When the instructions are executed individually or collectively by the at least one processor, the electronic device may determine whether a second packet loss rate of the non-cellular access network exceeds a second threshold based on the first packet loss rate exceeding the first threshold. When the above instructions are executed individually or collectively by the at least one processor, the electronic device may perform a handover from the non-cellular access network to the cellular access network through the communication circuit for the packet data session based on the second packet loss rate exceeding the second threshold. When the above instructions are executed individually or collectively by the at least one processor, the electronic device may perform a handover from the first CN node to the second CN node of the cellular network through the communication circuit for the packet data session based on the second packet loss rate not exceeding the second threshold.

[0278] In one embodiment, the instructions may enable the electronic device to obtain network metrics of a first packet data session connected through the non-cellular access network without passing through the cellular network, and to identify the second packet loss rate based on the collected network metrics.

[0279] In one embodiment, the instructions may cause the electronic device to determine the first threshold value based on the minimum required packet loss rate parameter indicated by the quality of service (QoS) profile of the packet data session.

[0280] In one embodiment, the instructions may cause the electronic device to perform a handover from the non-cellular access network to the cellular access network for the packet data session based on the third packet loss rate associated with the packet data session after the handover to the second CN node exceeding the first threshold.

[0281] In one embodiment, the first packet loss rate may be determined based on at least one of a DNS (domain name system) packet loss rate or a TCP (transmission control protocol) packet loss rate measured through the packet data session.

[0282] In one embodiment, the first packet loss rate may be determined based on at least one of the real-time transport protocol (RTP) packet loss rate measured through a second packet data session connected to the non-cellular access network and the first CN node, rather than the packet data session, or the ping packet loss rate measured through a ping test via the packet data session.

[0283] In one embodiment, the packet data session may be a non-IMS (Internet Protocol (IP) Multimedia Subsystem) PDU (packet data unit) session and the second packet data session may be an IMS PDU session. In one embodiment, the packet data session may be an IMS PDU session and the second packet data session may be a non-IMS PDU session.

[0284] In one embodiment, the non-cellular access network may include a Wi-Fi access point (AP).

[0285] In one embodiment, either the first CN node or the second CN node may be an N3IWF (non-3GPP (3rd generation partnership project) interworking function) and the other may be an ePDG (evolved packet data gateway).

[0286] In one embodiment, the cellular network may include at least one of an LTE (long term evolution) network or a 5G (5th generation) network.

[0287] A method performed by an electronic device (101) according to one embodiment of the present disclosure may include: an operation (1202) of establishing a packet data session through a first CN (core network) node of a non-cellular access network and a cellular network; an operation (1204) of determining whether a first packet loss rate associated with the packet data session exceeds a first threshold; an operation (1206) of determining whether a second packet loss rate of the non-cellular access network exceeds a second threshold based on the first packet loss rate exceeding the first threshold; an operation (1208) of performing a handover from the non-cellular access network to the cellular access network for the packet data session based on the second packet loss rate exceeding the second threshold; and an operation (1210) of performing a handover from the first CN node to the second CN node of the cellular network for the packet data session based on the second packet loss rate not exceeding the second threshold.

[0288] In one embodiment, the method may further include the operation of obtaining a network metric of a first packet data session connected through a non-cellular access network without passing through the cellular network, and the operation of identifying the second packet loss rate based on the collected network metric.

[0289] In one embodiment, the method may further include an operation to determine the first threshold value based on a minimum required packet loss rate parameter indicated by the quality of service (QoS) profile of the packet data session.

[0290] In one embodiment, the method may further include the operation of performing a handover from the non-cellular access network to the cellular access network for the packet data session based on the third packet loss rate associated with the packet data session after the handover to the second CN node exceeding the first threshold.

[0291] In one embodiment, the first packet loss rate may be determined based on at least one of a DNS (domain name system) packet loss rate or a TCP (transmission control protocol) packet loss rate measured through the packet data session.

[0292] In one embodiment, the first packet loss rate may be determined based on at least one of the real-time transport protocol (RTP) packet loss rate measured through a second packet data session connected to the non-cellular access network and the first CN node, rather than the packet data session, or the ping packet loss rate measured through a ping test via the packet data session.

[0293] In one embodiment, the packet data session may be a non-IMS (Internet Protocol (IP) Multimedia Subsystem) PDU (packet data unit) session, and the second packet data session may be an IMS PDU session. In one embodiment, the packet data session may be an IMS PDU session, and the second packet data session may be a non-IMS PDU session.

[0294] In one embodiment, the non-cellular access network may include a Wi-Fi access point (AP).

[0295] In one embodiment, either the first CN node or the second CN node may be an N3IWF (non-3GPP (3rd generation partnership project) interworking function) and the other may be an ePDG (evolved packet data gateway).

[0296] In one embodiment, the cellular network may include at least one of an LTE (long term evolution) network or a 5G (5th generation) network.

[0297] The electronic device according to the various embodiments disclosed in this document may be of various forms. The electronic device may include, for example, a portable communication device (e.g., a smartphone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, or a consumer electronics device. The electronic device according to the embodiments of this document is not limited to the devices described above.

[0298] The various embodiments of this document and the terms used therein are not intended to limit the technical features described in this document to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of said embodiments. In connection with the description of the drawings, similar reference numerals may be used for similar or related components. The singular form of a noun corresponding to an item may include one or more of said items unless the relevant context clearly indicates otherwise. In this document, phrases such as "A or B," "at least one of A and B," "at least one of A or B," "A, B or C," "at least one of A, B and C," and "at least one of A, B, or C" may each include any one of the items listed together in the corresponding phrase, or all possible combinations thereof. Terms such as "first," "second," or "first" or "second" may be used simply to distinguish said components from other said components and do not limit said components in any other aspect (e.g., importance or order). Where any (e.g., 1st) component is referred to as “coupled” or “connected” to another (e.g., 2nd) component, with or without the terms “functionally” or “communicationly,” it means that said any component may be connected to said other component directly (e.g., via a wire), wirelessly, or through a third component.

[0299] The term “module” as used in the various embodiments of this document may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with terms such as logic, logic block, component, or circuit, for example. A module may be a component formed integrally, or a minimum unit of said component or a part thereof that performs one or more functions. For example, according to one embodiment, a module may be implemented in the form of an application-specific integrated circuit (ASIC).

[0300] Various embodiments of the present document may be implemented as software (e.g., program (140)) comprising one or more instructions stored in a storage medium (e.g., internal memory (136) or external memory (138)) readable by a machine (e.g., electronic device (101)). For example, a processor (e.g., processor (120)) of the machine (e.g., electronic device (101)) may call at least one of the one or more instructions stored from the storage medium and execute it. This enables the machine to be operated to perform at least one function according to the at least one called instruction. The one or more instructions may include code generated by a compiler or code that can be executed by an interpreter. The storage medium readable by the machine may be provided in the form of a non-transitory storage medium. Here, 'non-temporary' simply means that the storage medium is a tangible device and does not contain a signal (e.g., electromagnetic waves), and the term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily.

[0301] According to one embodiment, the method according to the various embodiments disclosed herein may be provided by being included in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)) or an application store (e.g., Play Store). TM It can be distributed online (e.g., downloaded or uploaded) through ) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0302] According to various embodiments, each component (e.g., module or program) of the components described above may include a singular or multiple entities, and some of the multiple entities may be separated and placed in other components. According to various embodiments, one or more of the components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Generally or additionally, multiple components (e.g., module or program) may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the multiple components in the same or similar manner as those performed by the corresponding component among the multiple components prior to integration. According to various embodiments, operations performed by the module, program, or other components may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

Claims

1. In an electronic device (101), Communication circuit (192); At least one processor (120); and The electronic device includes a memory (130) for storing instructions, wherein the instructions are executed individually or collectively by the at least one processor, A packet data session is established through the first CN (core network) node of a non-cellular access network and a cellular network via the above communication circuit, and Determining whether the first packet loss rate related to the above packet data session exceeds the first threshold, Based on the fact that the first packet loss rate exceeds the first threshold, it is determined whether the second packet loss rate of the non-cellular access network exceeds the second threshold, and Based on the second packet loss rate exceeding the second threshold, a handover from the non-cellular access network to the cellular access network is performed for the packet data session through the communication circuit, and An electronic device that performs a handover from the first CN node to the second CN node of the cellular network through the communication circuit for the packet data session based on the fact that the second packet loss rate does not exceed the second threshold.

2. In claim 1, the instructions cause the electronic device, Obtaining network metrics of a first packet data session connected through the non-cellular access network without passing through the cellular network, and An electronic device that identifies the second packet loss rate based on the above network metric.

3. In claim 1 or 2, the instructions cause the electronic device, An electronic device that determines the first threshold value based on the minimum required packet loss rate parameter indicated by the quality of service (QoS) profile of the above packet data session.

4. In any one of claims 1 to 3, the instructions cause the electronic device, An electronic device that performs a handover from the non-cellular access network to the cellular access network for the packet data session based on the third packet loss rate associated with the packet data session exceeding the first threshold value after the handover to the second CN node.

5. In any one of claims 1 to 4, the first packet loss rate is An electronic device determined based on at least one of a DNS (domain name system) packet loss rate or a TCP (transmission control protocol) packet loss rate measured through the above packet data session.

6. In any one of claims 1 to 5, the first packet loss rate is An electronic device determined based on at least one of a real-time transport protocol (RTP) packet loss rate measured through a second packet data session connected to the non-cellular access network and the first CN node, rather than the packet data session, or a ping packet loss rate measured through a ping test via the packet data session.

7. In claim 6, the packet data session is a non-IMS (Internet Protocol (IP) Multimedia Subsystem) PDU (Packet Data Unit) session and the second packet data session is an IMS PDU session, or An electronic device in which the above packet data session is an IMS PDU session and the above second packet data session is a non-IMS PDU session.

8. In any one of claims 1 to 7, the non-cellular access network is an electronic device comprising a Wi-Fi access point (AP).

9. An electronic device according to any one of claims 1 to 8, wherein either the first CN node or the second CN node is an N3IWF (non-3GPP (3rd generation partnership project) interworking function) and the other is an ePDG (evolved packet data gateway).

10. An electronic device according to any one of claims 1 to 9, wherein the cellular network comprises at least one of an LTE (long term evolution) network or a 5G (5th generation) network.

11. In a method performed by an electronic device (101), Operation (1202) of establishing a packet data session through a first CN (core network) node of a non-cellular access network and a cellular network; An operation (1204) to determine whether the first packet loss rate related to the above packet data session exceeds a first threshold; An operation (1206) to determine whether the second packet loss rate of the non-cellular access network exceeds the second threshold based on the first packet loss rate exceeding the first threshold; An operation (1208) of performing a handover from the non-cellular access network to the cellular access network for the packet data session based on the second packet loss rate exceeding the second threshold; and A method comprising an operation (1210) of performing a handover from the first CN node to the second CN node of the cellular network for the packet data session based on the second packet loss rate not exceeding the second threshold.

12. In Paragraph 11, An operation to obtain network metrics of a first packet data session connected through the non-cellular access network without passing through the cellular network; An operation to identify the second packet loss rate based on the above network metric; and A method further comprising the operation of determining the first threshold value based on the minimum required packet loss rate parameter indicated by the quality of service (QoS) profile of the packet data session.

13. In Paragraph 11 or 12, A method further comprising the operation of performing a handover from the non-cellular access network to the cellular access network for the packet data session based on the third packet loss rate associated with the packet data session after the handover to the second CN node exceeding the first threshold.

14. In any one of claims 11 to 13, the first packet loss rate is Determined based on at least one of the DNS (domain name system) packet loss rate or the TCP (transmission control protocol) packet loss rate measured through the above packet data session, or A method determined based on at least one of a real-time transport protocol (RTP) packet loss rate measured through a second packet data session connected to the non-cellular access network and the first CN node, rather than the packet data session, or a ping packet loss rate measured through a ping test via the packet data session.

15. In Paragraph 14, The above packet data session is a non-IMS (Internet Protocol (IP) Multimedia Subsystem) PDU (Packet Data Unit) session, and the above second packet data session is an IMS PDU session, or A method in which the above packet data session is an IMS PDU session and the above second packet data session is a non-IMS PDU session.

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