Method and device for terminal-based configuration in wireless communication system

Abstract

A method performed by a base station in a wireless communication system, according to embodiments of the present disclosure, may comprise the steps of: receiving a first message including first information for identifying a terminal, second information about a cell trajectory, third information about a cell-related signal pattern, and fourth information indicating a failure type; identifying that the terminal moves along the cell trajectory on the basis of the first information and the second information; identifying that a signal pattern received from the terminal is similar to the signal pattern of the third information; and transmitting, to the terminal on the basis of the fourth information, a second message including configuration information for preventing a failure of the terminal.

Description

Method and device for terminal-based configuration in a wireless communication system

[0001] The present disclosure relates to a method and apparatus for terminal-based configuration in a wireless communication system. Specifically, it relates to a method and apparatus for applying terminal-based configuration to improve the communication quality of a subscriber according to a terminal failure type determined based on history.

[0002] Looking back at the evolution of wireless communication through successive generations, technologies have been developed primarily for human-oriented services, such as voice, multimedia, and data. Following the commercialization of 5G (5th Generation) communication systems, connected devices, which have been increasing explosively, are expected to be connected to communication networks. Examples of networked objects include vehicles, robots, drones, home appliances, displays, smart sensors installed in various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve into various form factors, such as augmented reality glasses, virtual reality headsets, and holographic devices. In the 6G (6th Generation) era, efforts are underway to develop improved 6G communication systems to connect hundreds of billions of devices and objects to provide diverse services. For this reason, 6G communication systems are being referred to as "beyond 5G" systems.

[0003] In the 6G communication system predicted to be realized around 2030, the maximum transmission speed is tera (i.e., 1,000 gigabit) bps (bit per second), and the wireless latency is 100 microseconds (μsec). In other words, compared to the 5G communication system, the transmission speed in the 6G communication system is 50 times faster, and the wireless latency is reduced to one-tenth.

[0004] To achieve such high data transmission speeds and ultra-low latency, 6G communication systems are being considered for implementation in the terahertz (THz) band (e.g., the 95 gigahertz (GHz) to 3 terahertz (3THz) band). Due to more severe path loss and atmospheric absorption phenomena compared to the millimeter wave (mmWave) band introduced in 5G, the importance of technologies capable of guaranteeing signal reach, or coverage, is expected to increase in the terahertz band. As key technologies to ensure coverage, new waveforms, beamforming, and multi-antenna transmission technologies such as massive Multiple-Input and Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas, which are superior in terms of coverage compared to RF (Radio Frequency) devices, antennas, and OFDM (Orthogonal Frequency Division Multiplexing), must be developed. In addition, new technologies such as metamaterial-based lenses and antennas, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS) are being discussed to improve the coverage of terahertz band signals.

[0005] In addition, to improve frequency efficiency and system network, development is underway in 6G communication systems for full duplex technology, in which uplink and downlink simultaneously utilize the same frequency resources at the same time; network technology that integrates satellites and HAPS (High-Altitude Platform Stations); network structure innovation technology that supports mobile base stations and enables network operation optimization and automation; dynamic spectrum sharing technology through collision avoidance based on spectrum usage prediction; AI-based communication technology that utilizes AI (Artificial Intelligence) from the design stage and internalizes end-to-end AI support functions to realize system optimization; and next-generation distributed computing technology that realizes services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high performance communication and computing resources (Mobile Edge Computing (MEC), cloud, etc.). In addition, attempts are continuing to further strengthen connectivity between devices, further optimize networks, promote the softwareization of network entities, and increase the openness of wireless communication through the design of new protocols to be used in 6G communication systems, the implementation of hardware-based security environments, the development of mechanisms for the safe utilization of data, and the development of technologies regarding privacy maintenance methods.

[0006] Due to the research and development of such 6G communication systems, it is expected that a new dimension of hyper-connected experience will become possible through the hyper-connectivity of 6G communication systems, which encompasses not only connections between objects but also connections between people and objects. Specifically, it is projected that 6G communication systems will enable the provision of services such as truly immersive eXtended Reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, services such as remote surgery, industrial automation, and emergency response, which are provided through 6G communication systems with enhanced security and reliability, will be applied in various fields including industry, healthcare, automotive, and home appliances.

[0007] One objective of the present disclosure may be to provide a method and apparatus for terminal-based configuration in communication systems such as 5G, 5G-Advanced, and 6G.

[0008] A method performed by a first base station in a wireless communication system according to embodiments of the present disclosure may include: receiving a first message comprising first information for identifying a terminal, second information regarding a cell trajectory, third information regarding a cell-related signal pattern, and fourth information indicating a type of failure; identifying that the terminal is moving along the cell trajectory based on the first information and the second information; identifying that the signal pattern received from the terminal is similar to the signal pattern of the third information; and transmitting a second message to the terminal, comprising setting information for preventing failure of the terminal, based on the fourth information.

[0009] In one embodiment, the first message is received from the NWDAF (network data analytics function) entity via the AMF (access and mobility management function) entity, and the first message may include any one of an INITIAL CONTEXT SETUP message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message.

[0010] In one embodiment, the first message is received from the second base station based on the Xn interface, and the first message may include either a HANDOVER REQUEST message or a RETRIEVE UE CONTEXT RESPONSE message.

[0011] In one embodiment, the failure type includes a first type indicating frequent cell changes, a second type indicating repetitive handover between two cells, or a third type indicating a connection failure. If the failure type is the first type, the configuration information may include configuration information for moving the terminal to a specific cell. If the failure type is the second type, the configuration information includes fifth information for adjusting the evaluation of signal quality regarding the cell, and the fifth information may include a cell individual offset (CIO). If the failure type is the third type, the configuration information may include information excluding cells where a connection failure occurs from the candidate cells selectable by the terminal.

[0012] In one embodiment, the signal pattern received from the terminal may include a signal pattern measured for the terminal's serving cell and a signal pattern measured for the terminal's neighboring cell.

[0013] In one embodiment, the signal pattern received from the terminal may include a pattern for at least one of RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), or SINR (signal to interference plus noise ratio).

[0014] The method and apparatus according to the embodiments of the present disclosure can more efficiently improve the communication quality of a subscriber in a wireless communication system.

[0015] Specifically, embodiments of the present disclosure may improve communication quality by applying terminal-based settings based on the terminal's history before the terminal experiences a failure.

[0016] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0017] The features and advantages of the embodiments of the present disclosure will become more apparent from the following description together with the accompanying drawings.

[0018] FIG. 1 illustrates a wireless communication system according to embodiments of the present disclosure.

[0019] FIG. 2 is a drawing for explaining the structure of a terminal according to embodiments of the present disclosure.

[0020] FIG. 3 is a drawing for explaining the structure of a network entity (or base station) according to embodiments of the present disclosure.

[0021] FIG. 4 illustrates examples of various failures experienced by a terminal according to embodiments of the present disclosure.

[0022] FIG. 5 illustrates an example of the operation of a network entity (core network, RAN) according to embodiments of the present disclosure.

[0023] FIG. 6 shows a cell signal pattern according to embodiments of the present disclosure.

[0024] FIG. 7 illustrates a method for terminal-based configuration according to embodiments of the present disclosure.

[0025] FIG. 8 illustrates a method for terminal-based configuration according to embodiments of the present disclosure.

[0026] FIG. 9 illustrates a method for terminal-based configuration according to embodiments of the present disclosure.

[0027] FIG. 10 shows an example of information for terminal-based configuration according to embodiments of the present disclosure.

[0028] FIG. 11 shows an example of information for terminal-based configuration according to embodiments of the present disclosure.

[0029] FIG. 12 shows an example of information for terminal-based configuration according to embodiments of the present disclosure.

[0030] FIG. 13 shows an example of a cell path history of a terminal according to embodiments of the present disclosure.

[0031] FIG. 14 illustrates the operation of a base station according to embodiments of the present disclosure.

[0032] FIG. 15 illustrates the operation of a network entity according to embodiments of the present disclosure.

[0033] Figure 16 shows an example of subscriber-level network optimization.

[0034] Figure 17 shows an example of an operation flowchart between a network, a RAN, and a UE.

[0035] Figure 18 shows a subscriber-specific mobility setting.

[0036] Figure 19 shows the results of a performance evaluation based on drive test data.

[0037] Figure 20 shows the problem situation and the extracted reference patterns.

[0038] Embodiments of the present disclosure may solve the problems and / or disadvantages described above and provide the advantages described below. One aspect of the present disclosure may provide a network entity (or node) and a method of communication thereof in a wireless communication system.

[0039] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art described in this disclosure. Terms used in this disclosure that are defined in a general dictionary may be interpreted as having the same or similar meaning as they have in the context of the relevant technology, and are not to be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure. In some cases, even terms defined in this disclosure are not to be interpreted to exclude the embodiments of this disclosure.

[0040] The various embodiments of the present disclosure described below illustrate a hardware-based approach. However, since the various embodiments of the present disclosure include techniques using both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0041] Additionally, various embodiments of the present disclosure describe various embodiments using terms used in some communication standards (e.g., 3GPP (3rd generation partnership project)), but this is merely for illustrative purposes. Various embodiments of the present disclosure can be easily modified and applied to other communication systems.

[0042] Various embodiments of the present disclosure are described below.

[0043] FIG. 1 illustrates a wireless communication system according to embodiments of the present disclosure.

[0044] FIG. 1 illustrates a base station (110), a first terminal (120), and / or a second terminal (130) as part of nodes utilizing a wireless channel in a wireless communication system. FIG. 1 illustrates only one base station, but this is merely an example. The wireless communication system of FIG. 1 may include other base stations identical or similar to the base station (110).

[0045] A base station (110) is a network infrastructure that provides wireless access to terminals (120, 130). The base station (110) has coverage defined as a certain geographical area based on the distance at which it can transmit signals. In addition to being a base station, the base station (110) may be referred to as an 'access point (AP)', 'evolved Node B (eNB)', 'next generation node B (gNB)', '5G node (5th generation node)', 'wireless point', 'transmission / reception point (TRP)', or other terms having an equivalent technical meaning.

[0046] Each of the first terminal (120) and the second terminal (130) is a device used by a user and can perform communication with the base station (110) via a wireless channel. At least one of the first terminal (120) or the second terminal (130) can be operated without user involvement. For example, at least one of the first terminal (120) or the second terminal (130) may be a device that performs machine type communication (MTC) and may not be carried by the user. Each of the first terminal (120) and the second terminal (130) may be referred to as 'user equipment (UE)', 'mobile station', 'subscriber station', 'customer premises equipment (CPE)', 'remote terminal', 'wireless terminal', 'electronic device', or 'user device' or other terms having an equivalent technical meaning.

[0047] The base station (110), the first terminal (120), and the second terminal (130) can transmit and / or receive wireless signals in a millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz). At this time, to improve channel gain, the base station (110), the first terminal (120), and / or the second terminal (130) can perform beamforming.

[0048] Beamforming may include transmitting beamforming and / or receiving beamforming. That is, the base station (110), the first terminal (120), and / or the second terminal (130) may give directivity to the transmitted signal or the received signal. To give directivity to the received signal, the base station (110) and / or the terminals (120, 130) may select serving beams (112, 113, 121, 131) through a beam search or beam management procedure. After the serving beams (112, 113, 121, 131) are selected, subsequent communication may be performed through a resource that is in a quasi-co-located (QCL) relationship with the resource that transmitted the serving beams (112, 113, 121, 131).

[0049] The base station (110), the first terminal (120), and the second terminal (130) of the present disclosure may each be a transmitting apparatus, a transmitting node, a receiving apparatus, and / or a receiving node. For example, the base station (110) may transmit a radio frequency (RF) signal to the first terminal (120). The base station (110) may receive an RF signal from the first terminal (120). As another example, the first terminal (120) may transmit an RF signal to the base station (110) or the second terminal (130). The first terminal (120) may receive an RF signal from the base station (110) or the second terminal (130).

[0050] FIG. 2 is a drawing for explaining the structure of a terminal according to embodiments.

[0051] Referring to FIG. 2, a terminal (200) according to embodiments may include a transceiver (transmitter / receiver) (210), a memory (220), and / or a processor (230). Although the present disclosure describes the terminal (200) as including a transceiver (210), a memory (220), and / or a processor (230), this is merely an example. For example, the terminal (200) may include additional components other than the transceiver (210), the memory (220), and the processor (230).

[0052] According to the embodiments, the transceiver (210), memory (220), and processor (230) may each be implemented or formed as separate chips. However, this is merely an example, and the transceiver (210), memory (220), and / or processor (230) may be implemented or formed as a single chip.

[0053] According to embodiments, the transceiver (210) may include at least one transmitter and / or at least one receiver. For example, the transceiver (210) may include an RF transmitter for amplifying and up-converting the frequency of a transmitted signal. The transceiver (210) may include an RF receiver for down-converting the frequency of a received signal and amplifying low-noise.

[0054] The configurations of the transceiver (210) described in this disclosure are merely examples and the configuration of the transceiver (210) is not limited to an RF transmitter and an RF receiver. For example, the transceiver (210) may further include a coupler to ensure isolation between the RF transmitter and the RF receiver.

[0055] According to the embodiments, the transceiver (210) can transmit or receive a signal to or from the processor (230). For example, the transceiver (210) can transmit or deliver an RF signal received through a wireless communication channel to or from the processor (230). The transceiver (210) can receive or receive an RF signal from or from the processor (230).

[0056] According to the embodiments, the transceiver (210) may be referred to as a UE transmitter or a UE receiver.

[0057] According to embodiments, the transceiver (210) may transmit a signal to a base station (e.g., base station (110) of FIG. 1) or a network entity (e.g., an access and mobility management function (AMF) entity) or receive a signal from a base station or a network entity. In embodiments, the transmitted or received signal may include control signals and data.

[0058] According to embodiments, the memory (220) may include or store programs and data necessary for the operations of the terminal (200). For example, the memory (220) may be a non-transitory memory, and a program stored in the non-transitory memory may be organically coupled with the hardware configuration of the terminal (200) (e.g., a processor (230) or a transceiver (210)). The memory (220) may store control information or data including signals obtained by the terminal (200). In embodiments, the memory (220) may include a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, a DVD, and / or a storage medium.

[0059] According to the embodiments, the processor (230) may include one processor or a plurality of processors. For example, the processor (230) may include a communication processor. For example, the processor (230) may include a communication processor and / or an application processor.

[0060] According to embodiments, the processor (230) can control a series of processes performed by the terminal (200). For example, the transceiver (210) can receive a data signal containing control information transmitted by a base station or network entity. The processor (230) can process the received control signal and data signal.

[0061] The term processor in the present disclosure may be replaced with various terms referring to a configuration that executes or performs operations of the terminal (200). For example, the processor may be replaced with a controller or a computing circuit.

[0062] The terminal (200) of the present disclosure may correspond to the first terminal (120) and / or the second terminal (130) of FIG. 1.

[0063] FIG. 3 is a diagram illustrating the structure of a network entity (or base station) according to embodiments.

[0064] Referring to FIG. 3, a network entity (300) according to embodiments may include a transceiver (transmitter / receiver) (310), a memory (320), and / or a processor (330). Although the present disclosure describes the network entity (300) as including a transceiver (310), a memory (320), and / or a processor (330), this is merely an example. For example, the network entity (300) may include additional components other than the transceiver (310), the memory (320), and the processor (330). The network entity (300) may represent network functions included in a base station or other core network.

[0065] According to the embodiments, the transceiver (310), memory (320), and processor (330) may each be implemented or formed as separate chips. However, this is merely an example, and the transceiver (310), memory (320), and / or processor (330) may be implemented or formed as a single chip.

[0066] According to embodiments, the transceiver (310) may include at least one transmitter and / or at least one receiver. For example, the transceiver (310) may include an RF transmitter for amplifying and up-converting the frequency of a transmitted signal. The transceiver (310) may include an RF receiver for down-converting the frequency of a received signal and amplifying low-noise.

[0067] The configurations of the transceiver (310) described in this disclosure are merely examples and are not limited to an RF transmitter and an RF receiver. For example, the transceiver (310) may further include a coupler to ensure isolation between the RF transmitter and the RF receiver.

[0068] According to the embodiments, the transceiver (310) can transmit or receive a signal to or from the processor (330). For example, the transceiver (310) can transmit or deliver an RF signal received through a wireless communication channel to or from the processor (330). The transceiver (310) can receive or receive an RF signal from the processor (230).

[0069] According to the embodiments, the transceiver (310) may be referred to as a network entity transmitter or a network entity receiver.

[0070] According to embodiments, the transceiver (310) may transmit a signal to the terminal (200) or another network entity or receive a signal from the terminal (200) or another network entity. In embodiments, the transmitted or received signal may include control signals and data.

[0071] According to embodiments, the memory (320) may contain programs and data necessary for the operations of the network entity (300). For example, the memory (320) may be a non-transitory memory, and a program stored in the non-transitory memory may be organically coupled with the hardware configuration of the network entity (300) (e.g., a processor (330) or a transceiver (310)). The memory (320) may store control information or data including signals obtained by the network entity (300). In embodiments, the memory (320) may include read-only memory (ROM), random access memory (RAM), a hard disk, a CD-ROM, a DVD, and / or storage media.

[0072] According to the embodiments, the processor (330) may include one processor or a plurality of processors. For example, the processor (330) may include a communication processor. For example, the processor (330) may include a communication processor and / or an application processor.

[0073] According to embodiments, the processor (330) can control a series of processes performed by the network entity (300). For example, the transceiver (310) can receive a data signal containing control information transmitted by a terminal or another network entity. The processor (330) can process the received control signal and data signal.

[0074] The term processor in the present disclosure may be replaced with various terms referring to a configuration that executes or performs operations of a network entity (300). For example, processor may be replaced with a controller or a computing unit.

[0075] The network entity (300) of the present disclosure may correspond to the base station (110) of FIG. 1.

[0076] The device described in FIGS. 2 and 3 may correspond to a device of a transmitting end or a receiving end. A terminal or network entity according to embodiments of the present disclosure may be a transmitting end when it is a transmitting end, and may be a receiving end when the terminal or network entity is a receiving end.

[0077] The terminal, base station, or network entity described in FIGS. 1 to 3 can perform operations to apply terminal-based settings in relation to repetitive failures experienced by the terminal.

[0078] FIG. 4 illustrates examples of various failures experienced by a terminal according to embodiments of the present disclosure.

[0079] Referring to FIG. 4, scenarios for various failure cases experienced by a terminal (or user equipment) (UE) are illustrated. In FIG. 4, 410 represents the location or activity over time for the user (or subscriber) of the terminal. Specifically, the user is at home from 0:00 to 8:00, is on their way to work from 8:00 to 9:00, and is at the office from 9:00 to 12:00. Then, the user spends time for lunch and a walk from 12:00 to 13:00, is at the office from 13:00 to 18:00, and may be moving out of the office from 18:00 to 19:00. Then, the user spends time for dinner from 19:00 to 21:00, is on their way home from 21:00 to 22:00, and is at home from 22:00 to 24:00.

[0080] In this scenario, the terminal between 8:00 and 9:00 performs frequent handovers while the user is commuting to work (432), and the terminal between 12:00 and 13:00 experiences a ping-pong problem (434). The ping-pong problem can manifest as a phenomenon where the terminal repeatedly performs handovers between two cells. Additionally, the terminal between 21:00 and 22:00 fails to connect to a specific cell while the user is moving home (436).

[0081] In connection with the failure of terminals such as 432, 434 and 436, traffic problems may occur (440), and the interference of data due to the failure and the burden of transmission and reception operations for control plane signaling may cause such traffic degradation.

[0082] Cell-based settings are applied when a terminal moves between cells; however, since these settings do not take into account the specific circumstances of each terminal connected to a cell, failures experienced by a particular terminal may occur repeatedly. For example, similar failures may occur repeatedly every day for a terminal that travels along a similar route. However, if terminal-based settings are applied before a specific terminal fails, the failure can be prevented.

[0083] The method and apparatus according to the embodiments of the present disclosure can prevent failure of a terminal and improve user satisfaction with communication services by ensuring that terminal-based settings are applied in advance before the terminal experiences failure.

[0084] FIG. 5 illustrates an example of the operation of a network entity (core network or RAN) according to embodiments of the present disclosure.

[0085] Referring to FIG. 5, an example of the operation of a core network (510) and a RAN (radio access network) (520) is illustrated. The core network (510) may represent a network data analytics function (NWDAF) entity or other network entities. The RAN (520) is 3GPP (3 rd It can be referred to as the gNB (next generation node B) of the NR (new radio) network of the generation partnership project, the eNB (evolved node B) of the LTE (long term evolution) network, or a base station.

[0086] The core network (510) may receive information related to the history of the terminal. Information related to the history of the terminal may include information about the terminal's path, that is, the cell trajectory to which the terminal is connected, and information about the terminal's failures and / or traffic information. Information about the cell trajectory may indicate the cells to which the terminal is connected in order and may include information about the time the connection to the cell was maintained. The cells may be indicated by cell identifiers. Information about failures may indicate information about the type of failure experienced by the terminal. For example, failures may include frequent handovers, ping-pong problems, or connection failure problems of the terminal. Connection failure problems may include connection failures or re-establishment failures for specific cells. The core network (510) may identify what failures the terminal has experienced by receiving information indicating the type of failure experienced by the terminal or by receiving information related to the terminal's failures.

[0087] Additionally, the core network (510) may receive information regarding cell signal patterns measured by the terminal. For example, the core network (510) may receive information regarding cell signal patterns, such as RSRP (reference signal received power) or RSRQ (reference signal received quality), measured by the terminal. The cell signal pattern may include continuous measurement values ​​for the terminal's serving cell or neighboring cell. The pattern of signals for the serving cell or neighboring cell measured by the terminal while moving may be formed in a specific shape according to the terminal's movement path. A sequence of measurement values ​​for the serving cell and neighboring cell continuously measured by the terminal over a specific period of time may correspond to the terminal's movement path. Therefore, the terminal's movement path and the pattern of cell signals measured by the terminal may correspond to each other, and the measured signal pattern may be understood as information representing the terminal's movement path.

[0088] Information regarding the failure of a terminal may indicate the type of failure experienced by the terminal, or may indicate relevant information capable of analyzing or identifying the type of failure experienced by the terminal. The failure of the terminal may include frequent handovers, ping-pong, or connection failures. However, the failure of the terminal is not limited to the aforementioned cases and may include various additional cases.

[0089] In various embodiments, the core network (510) may define frequent handover based on the number of terminal handovers per unit time, or define frequent handover based on the average connection maintenance time per cell. Additionally, the core network (510) may define a ping-pong problem based on the number of times a handover is repeated between two cells.

[0090] In various embodiments, the core network (510) may define a connection failure based on the number of connection failures of terminals per unit time, or based on the average time taken until re-establishment. Additionally, the core network (510) may define a connection failure based on the ratio of cases where the failed cell and the re-established cell are different.

[0091] In various embodiments, terminal failure may be defined by considering traffic information. For example, since the user may feel significant inconvenience when a terminal is interrupted while using meaningful traffic, the core network (510) may analyze terminal failure by considering the history of the terminal's traffic.

[0092] In various embodiments, the core network (510) may receive information related to the history of the terminal based on a minimization of drive test (MDT). An MDT may refer to physically collecting data using a vehicle or equipment (such as a terminal) to measure the quality of a communication network, and the collected data related to the history of the terminal may be transmitted to the core network (510). The information related to the history of the terminal may be referred to as MDT data.

[0093] The core network (510) can determine the failure path of a terminal regarding a failure that the terminal repeatedly experiences from information related to the terminal's history. For example, if the terminal experiences a failure in cell C while moving in the order of cell A, cell B, and cell C, and the failure occurs repeatedly when the terminal moves along the same path, the core network (510) can analyze that the same problem is repeated when the terminal moves along a specific path based on information related to the terminal's history, and can identify the path of the terminal that causes the repeated failure.

[0094] The core network (510) can determine the failure path of a terminal related to the failure of a terminal based on information related to the history of the terminal. The core network (510) can also generate information for identifying the terminal experiencing failure (e.g., terminal identifier), the failure path of the terminal, and information about the type of failure. In this case, the failure path of the terminal may represent the cell trajectory and / or cell signal pattern of the terminal.

[0095] The core network (510) can generate a representative cell trajectory to indicate the failure path of the terminal. For example, the core network (510) can generate a representative cell trajectory to indicate the failure path of the terminal based on cell trajectories that are repeatedly received according to the repeated failures of the terminal. The representative cell trajectory can be used to identify whether the terminal is moving along the failure path by comparing it with the cell trajectory that the terminal actually moved along by the base station.

[0096] The core network (510) can generate a representative cell signal pattern to indicate the failure path of the terminal. For example, the core network (510) can generate a representative cell signal pattern to indicate the failure path of the terminal based on a cell-related signal pattern that is repeatedly received according to the repeated failure of the terminal. The representative cell signal pattern can be used to identify whether the terminal is moving along the failure path by comparing it with a cell signal pattern measured at the terminal by a base station.

[0097] In various embodiments, the core network (510) may output an identifier of a terminal related to failure, information about the failure path of the terminal (representative cell trajectory or representative cell signal pattern), and / or information about the type of failure based on an artificial intelligence model from the collected information. Additionally, pre-processing of the collected information and post-processing of the output information may be performed for data processing based on the artificial intelligence model.

[0098] In various embodiments, even if the history information obtained by the core network (510) does not include a history of a specific failure for a specific terminal, the core network (510) may anticipate that a specific terminal will fail if it follows a certain failure path. For example, even if the history information obtained by the core network (510) includes a history of a first failure for terminal A but does not include a history of a first failure for terminal B, the core network (510) may derive a failure path for a first failure for terminal B.

[0099] The core network (510) can transmit information for identifying a terminal, the terminal's failure path, and the failure type to the RAN (520). The RAN (520) can receive the terminal's identifier related to the failure and the terminal's failure path and / or failure type from the core network (510). Additionally, the RAN (520) can receive information related to the cell to which the terminal is connected and / or the cell signal pattern measured by the terminal from the terminal. Furthermore, the RAN (520) can calculate the similarity between the information received from the core network (510) and the information received from the terminal, and the RAN (520) can transmit terminal-based configuration information to the terminal based on the similarity. For example, if the RAN (520) determines that there is a high similarity between the received information, the RAN (520) determines that the terminal is moving along the failure path and is likely to experience a failure, and can transmit terminal-based configuration information to the terminal. On the other hand, if the RAN (520) determines that there is not a high degree of similarity between the received information, the RAN (520) may not transmit terminal-based configuration information to the terminal, as it determines that the terminal does not move along the failure path and is unlikely to experience failure. The operation of calculating similarity may be performed based on an artificial intelligence model or algorithm, and the similarity may be determined by comparing the calculated similarity with an arbitrary threshold.

[0100] In various embodiments, the core network may transmit information to the base station through the access and mobility management function (AMF) or other management servers.

[0101] The apparatus and method according to the embodiments of the present disclosure can derive a failure path of a terminal for failures that the terminal repeatedly experiences in a core network and identify whether the terminal moves along the failure path in a RAN, thereby performing terminal-based configuration before the terminal fails. Accordingly, the quality of communication services experienced by the user of the terminal can be improved.

[0102] FIG. 6 shows a cell signal pattern according to embodiments of the present disclosure.

[0103] Referring to Fig. 6, a cell signal pattern associated with terminal failure is illustrated.

[0104] The cell signal pattern may include cell signal patterns measured by the terminal for a serving cell and / or multiple neighboring cells. Additionally, the cell signal pattern may include patterns for various reference signals, such as RSRP (reference signal received power) and RSRQ (reference signal received quality).

[0105] Figure 6 shows the RSRP signal pattern measured when the terminal experiences frequent handovers or ping-pong, and the RSRP signal pattern measured when the terminal fails to connect wirelessly.

[0106] 610 indicates the RSRP signal pattern measured when the terminal experiences frequent handovers or ping-pong, and 620 indicates when the terminal experiences a wireless connection failure.

[0107] Cell signal patterns measured by the terminal are transmitted to the core network and can be used to analyze the terminal's failure path. The core network can generate a representative cell signal pattern based on the cell signal pattern associated with the terminal's failure and transmit the generated representative cell signal pattern to the base station to which the terminal is connected. Upon receiving the representative cell signal pattern, the base station can identify whether the terminal is moving along the failure path by calculating the similarity between the representative cell signal pattern and the cell signal pattern received from the terminal.

[0108] In various embodiments, the cell signal pattern may include a measurement value for at least one of RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), or SINR (signal to interference plus noise ratio).

[0109] In various embodiments, the cell signal pattern may include measured values ​​of signals for a plurality of neighboring cells.

[0110] FIG. 7 illustrates a method for terminal-based configuration according to embodiments of the present disclosure.

[0111] Referring to FIG. 7, the operation of a network data analytic function (NWDAF), an access and mobility management function (AMF), a first base station, and a terminal for terminal-based configuration is illustrated. The NWDAF may correspond to the core network of FIG. 5, and the first base station may correspond to the RAN of FIG. 5. The terminal may correspond to the terminal of FIG. 2, and the NWDAF, AMF, or the first base station may correspond to the network entity of FIG. 3.

[0112] In step 712, the NWDAF may receive information related to the terminal's history. Information related to the terminal's history may include information about the terminal's path, i.e., the cell trajectory to which the terminal is connected, and information about the terminal's failures and / or traffic information. Information about the cell trajectory may indicate the cells to which the terminal is connected in order and may include information about the time the connection to the cell was maintained. The cells may be indicated by cell identifiers. Information about failures may indicate information about the type of failure experienced by the terminal. For example, failures may include the terminal's frequent handovers, ping-pong issues, or connection failure issues. Connection failure issues may include connection failures or re-establishment failures for specific cells. The NWDAF may identify which failures the terminal has experienced by receiving information indicating the type of failure experienced by the terminal or by receiving information related to the terminal's failures.

[0113] Additionally, the NWDAF can receive information regarding cell signal patterns measured by the terminal. For example, the NWDAF can receive information regarding cell signal patterns, such as RSRP (reference signal received power) or RSRQ (reference signal received quality), measured by the terminal. The cell signal pattern may include continuous measurement values ​​for the terminal's serving cell or neighboring cells. The signal pattern for the serving cell or neighboring cells measured by the terminal while moving may take on a specific form depending on the terminal's movement path. A sequence of measurement values ​​for the serving cell and neighboring cells continuously measured by the terminal over a specific period of time may correspond to the terminal's movement path. Therefore, the terminal's movement path and the cell signal pattern measured by the terminal may correspond to each other, and the measured signal pattern may be understood as information representing the terminal's movement path.

[0114] Information regarding the failure of a terminal may indicate the type of failure experienced by the terminal, or may indicate relevant information capable of analyzing or identifying the type of failure experienced by the terminal. The failure of the terminal may include frequent handovers, ping-pong, or connection failures. However, the failure of the terminal is not limited to the aforementioned cases and may include various additional cases.

[0115] In various embodiments, NWDAF may define frequent handover based on the number of terminal handovers per unit time, or define frequent handover based on the average connection maintenance time per cell. Additionally, NWDAF may define a ping-pong problem based on the number of times a handover is repeated between two cells.

[0116] In various embodiments, NWDAF may define a connection failure based on the number of connection failures of a terminal per unit time, or based on the average time taken until re-establishment. Additionally, NWDAF may define a connection failure based on the ratio of cases where failed cells and re-established cells are different.

[0117] In various embodiments, terminal failure can be defined by considering traffic information. For example, since user inconvenience is significant when a terminal is interrupted while using meaningful traffic, NWDAF can analyze terminal failure by considering the history of the terminal's traffic.

[0118] In various embodiments, the NWDAF may receive information related to the history of the terminal based on the minimization of drive test (MDT). The MDT may refer to physically collecting data using a vehicle or equipment (such as a terminal) to measure the quality of a communication network, and the collected data related to the history of the terminal may be transmitted to the NWDAF. The information related to the history of the terminal may be referred to as MDT data.

[0119] NWDAF can determine the failure path of a terminal regarding failures that the terminal repeatedly experiences based on information related to the terminal's history. For example, if a terminal experiences a failure in Cell C while moving in the order of Cell A, Cell B, and Cell C, and that failure occurs repeatedly when the terminal moves along the same path, NWDAF can analyze that the same problem recurs when the terminal moves along a specific path based on information related to the terminal's history, and can identify the terminal's path that causes the recurring failures.

[0120] Specifically, the NWDAF can determine the path of a terminal related to a terminal failure through information related to the terminal's history. For example, the NWDAF can generate information to identify the terminal experiencing the failure (e.g., a terminal identifier), the failure path of the terminal related to the failure, and information regarding the type of failure. In this case, the terminal's path may represent the terminal's cell trajectory or cell signal pattern. The NWDAF can generate a cell signal pattern related to the terminal's failure. For example, regarding repeated terminal failures, the NWDAF can generate a representative cell signal pattern based on multiple cell-related signal patterns measured in the relevant cell immediately before the terminal experiences the failure. The representative cell signal pattern can be compared with cell signal patterns measured by the terminal subsequently to identify whether the terminal is moving along a path where it may experience failure. Since the cell trajectory or cell signal pattern related to the terminal's failure generated by the NWDAF specifies a single failure path based on the terminal's history information repeatedly received by the NWDAF, it may be referred to as a representative cell trajectory or a representative cell signal pattern.

[0121] In various embodiments, the NWDAF may output information regarding the terminal associated with the failure, the failure path of the terminal, the type of failure, and / or the cell signal pattern associated with the failure, based on an artificial intelligence model from the collected information. The information output from the NWDAF is transmitted to a base station and can be used by the base station to identify the path along which the terminal is moving.

[0122] In step 714, the terminal may be connected to a cell operated by the first base station. For example, the terminal may be connected to the first base station by camping on the first base station, or by a handover, cell selection, or cell reselection operation. The cell operated by the first base station may be a cell associated with the terminal's failure path.

[0123] In step 716, the NWDAF may transmit information for identifying the terminal, the terminal's failure path (cell trajectory or cell signal pattern, etc.) related to the terminal's failure, and information regarding the terminal's failure type to the first base station via the AMF. Step 716 may be triggered by the terminal connecting to a cell operated by the first base station. For example, when the NWDAF recognizes that the terminal is connected to a cell operated by the first base station, the NWDAF may identify that the cell is included in the terminal's failure path and transmit information for terminal-based configuration to the first base station via the AMF. Although the transmission and reception operations between the NWDAF and the AMF are omitted in FIG. 7, operations may be included for transmitting and receiving a message to indicate that the terminal is connected to a cell included in the failure path, or for transmitting and receiving a message containing information for tracking the terminal's path (terminal identifier, failure path, and information regarding the failure type, etc.).

[0124] When a terminal is connected to a path (or cell) associated with the terminal's failure, the NWDAF can transmit information to a first base station operating the cell to which the terminal is connected (e.g., terminal identifier), the terminal's failure path associated with the terminal's failure (e.g., cell trajectory or cell signal pattern), and information regarding the type of failure of the terminal via the AMF so that the terminal can track whether the terminal is moving along the failure path. Based on the received information, the first base station can identify the terminal connected to the cell and track whether the identified terminal is moving along the failure path.

[0125] In various embodiments, when information is transmitted from the NWDAF to the base station via the AMF, the information transmitted from the AMF to the base station may be included in an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message. In this case, the INITIAL CONTEXT SETUP REQUEST message, the UE CONTEXT MODIFICATION REQUEST message, or the PATH SWITCH REQUEST ACKNOWLEDGE message may represent messages based on the NGAP (next generation application protocol). NGAP represents a protocol related to control plane communication between the base station and the core network.

[0126] The INITIAL CONTEXT SETUP REQUEST message represents a message for setting the initial context of the terminal, and the UE CONTEXT MODIFICATION REQUEST message represents a message for updating context information or settings related to the terminal. The PATH SWITCH REQUEST ACKNOWLEDGE message is a message transmitted in response to the PATH SWITCH REQUEST message and can be used to notify the base station that a new path has been established after the terminal's handover.

[0127] In step 718, the first base station may receive from the terminal information regarding the cell to which the terminal is connected and / or a cell signal pattern measured by the terminal. The cell signal pattern may include a pattern for RSRP or a pattern for RSRQ measured by the terminal, and may include measurements for the serving cell and neighboring cells. The cell signal pattern received by the first base station from the terminal may be compared with a representative cell signal pattern received by the first base station from the NWDAF to identify whether the terminal is moving along a failure path.

[0128] In various embodiments, the first base station may transmit a message to the terminal requesting measurement of a cell signal. At this time, the first base station may set the measurement period or measurement time of the cell signal to the terminal. For example, the first base station may set the terminal to measure the cell signal at a period of 120ms. Additionally, the first base station may set a period of 40ms, 64ms, 80ms, or 100ms, etc., to determine whether the conditions of Event A1 are satisfied in relation to Event A1 measurement. The first base station may separately request the terminal to measure the cell signal in order to track the terminal's path.

[0129] In step 720, the first base station can track the movement path of the terminal. Based on the information received in step 716 and the information regarding the cell trajectory the terminal actually moved, the first base station can identify whether the terminal is moving along a failure path. The information regarding the cell trajectory the terminal actually moved along may include the history of the cells to which the terminal is connected and the period during which the terminal was connected to each cell. The information regarding the cell trajectory the terminal actually moved along may be referred to as UE History Information. UE History Information is managed by the base station to which the terminal is connected and may be transmitted between base stations (or via AMF) when the terminal moves between base stations.

[0130] For example, the first base station can determine whether the path of the cell the terminal moved to matches the cell trajectory information received in step 716. In various embodiments, whether the path of the cell the terminal moved to is similar to the cell trajectory information can be determined based on an artificial intelligence model.

[0131] In step 722, the first base station can identify whether the terminal is moving along a failure path within the cell by comparing the cell signal pattern received from the terminal in step 718 with the representative cell signal pattern received from the NWDAF in step 716. Specifically, the comparison of cell signal patterns can be performed by determining the similarity between the cell signal patterns. The first base station derives the similarity between the terminal's cell signal pattern and the cell signal pattern of the failure path based on an artificial intelligence model or other algorithm, and can determine that the terminal is moving along the failure path if the similarity is greater than or equal to a specific threshold. On the other hand, if the similarity between the cell signal patterns is less than a specific threshold, the first base station can determine that the terminal is not moving along the failure path.

[0132] In various embodiments, the base station may select a cell to perform a similarity determination of cell signal patterns based on the time the terminal has maintained a connection to the cell. For example, if the time the terminal has maintained a connection to the cell is less than a specific threshold, the base station may not use the cell signal pattern measured by the terminal in that cell for similarity calculation, but may use the cell signal pattern measured in the cell to which the terminal was previously connected.

[0133] In step 724, if the first base station determines that the terminal is moving along a failure path, the first base station may transmit terminal-based configuration information to the terminal. That is, the first base station may transmit appropriate configuration information to the terminal so that the terminal does not experience a failure. Based on information regarding the type of failure among the information received in step 716, the first base station may transmit configuration information to the terminal to prevent the terminal from experiencing the corresponding failure.

[0134] In various embodiments, if the failure type received in step 716 indicates a frequent handover of the terminal, the first base station may transmit terminal-based configuration information to the terminal so that the terminal can hand over to a cell that services a wide range. The handover may include an inter-frequency handover or an inter-RAT (radio access technology) handover.

[0135] In various embodiments, if the failure type received in step 716 indicates a ping-pong (repeated handover between two cells) of the terminal, the first base station may transmit to the terminal configuration information in which the cell individual offset (CIO) is adjusted so that the terminal does not easily perform a handover to that cell. The CIO may represent information for adjusting the evaluation of signal quality regarding the cell. Thus, through the adjusted CIO, the evaluation of signal quality regarding the cell is adjusted so that the handover of the terminal to a specific cell can be suppressed.

[0136] In various embodiments, if the failure type received in step 716 indicates a terminal's repeated connection failure or a long time until re-establishment, indicating difficulty in connecting to a specific cell, the first base station may transmit configuration information to the terminal to exclude the cell from candidate cells so that the terminal does not attempt to connect to the cell.

[0137] In the embodiments of the present disclosure, the failure types of the terminal are not limited to those described above, and various failure types may be set according to the definition of failure, and various terminal-based configuration information to prevent such failure types may be applied. Even if specific names of configuration parameters are not designated in the embodiments of the present disclosure, adjustments to configuration parameters within the range applicable by a person skilled in the art may be understood as described in the present disclosure.

[0138] In step 726, the terminal can apply the terminal-based configuration information received in step 724. Therefore, even if the terminal moves in a manner similar to the failure path, the expected failure can be prevented in advance by applying terminal-based configuration information (or terminal-specific configuration information) instead of cell-based configuration information.

[0139] In various embodiments, if the base station does not receive information about the terminal's failure path and failure type from the NWDAF, the base station may compare the cell signal pattern collected from the terminal with the cell signal pattern by failure type stored in itself, and perform terminal-based configuration according to the failure type corresponding to the cell signal pattern with the highest similarity.

[0140] The operations of the embodiment described in FIG. 7 may be changed in order, some operations may be omitted, separate operations may be merged to perform a single operation, or a single operation may be performed separately. Additionally, the operations of the embodiment described in FIG. 7 may be combined with operations of other embodiments described in the present disclosure to form new embodiments. Embodiments according to variations and combinations of the embodiments of the present disclosure may be understood as described by the present disclosure to the extent that they are derivable by a person skilled in the art.

[0141] FIG. 8 illustrates a method for terminal-based configuration according to embodiments of the present disclosure.

[0142] Referring to FIG. 8, the operation of a network data analytic function (NWDAF), an access and mobility management function (AMF), a first base station, a second base station, and a terminal for terminal-based configuration is illustrated. The NWDAF can correspond to the core network of FIG. 5, and the first base station and the second base station can correspond to the RAN of FIG. 5. The terminal can correspond to the terminal of FIG. 2, and the NWDAF, AMF, the first base station, and the second base station can correspond to the network entity of FIG. 3.

[0143] An embodiment of FIG. 8 illustrates the operation of each entity for terminal-based configuration when a terminal moves along a failure path through cells operated by a first base station and a second base station. Specifically, the embodiment of FIG. 8 may represent a case where the terminal's failure path includes cells operated by a first base station and cells operated by a second base station, and the terminal's failure is likely to occur in a cell operated by the first base station.

[0144] In step 812, the NWDAF may receive information related to the terminal's history. Information related to the terminal's history may include information about the terminal's path, i.e., the cell trajectory to which the terminal is connected, and information about the terminal's failures and / or traffic information. Information about the cell trajectory may indicate the cells to which the terminal is connected in order and may include information about the time the connection to the cell was maintained. The cells may be indicated by cell identifiers. Information about failures may indicate information about the type of failure experienced by the terminal. For example, failures may include the terminal's frequent handovers, ping-pong issues, or connection failure issues. Connection failure issues may include connection failures or re-establishment failures for specific cells. The NWDAF may identify which failures the terminal has experienced by receiving information indicating the type of failure experienced by the terminal or by receiving information related to the terminal's failures.

[0145] Additionally, the NWDAF can receive information regarding cell signal patterns measured by the terminal. For example, the NWDAF can receive information regarding cell signal patterns, such as RSRP (reference signal received power) or RSRQ (reference signal received quality), measured by the terminal. The cell signal pattern may include continuous measurement values ​​for the terminal's serving cell or neighboring cells. The signal pattern for the serving cell or neighboring cells measured by the terminal while moving may take on a specific form depending on the terminal's movement path. A sequence of measurement values ​​for the serving cell and neighboring cells continuously measured by the terminal over a specific period of time may correspond to the terminal's movement path. Therefore, the terminal's movement path and the cell signal pattern measured by the terminal may correspond to each other, and the measured signal pattern may be understood as information representing the terminal's movement path.

[0146] Information regarding the failure of a terminal may indicate the type of failure experienced by the terminal, or may indicate relevant information capable of analyzing or identifying the type of failure experienced by the terminal. The failure of the terminal may include frequent handovers, ping-pong, or connection failures. However, the failure of the terminal is not limited to the aforementioned cases and may include various additional cases.

[0147] In various embodiments, NWDAF may define frequent handover based on the number of terminal handovers per unit time, or define frequent handover based on the average connection maintenance time per cell. Additionally, NWDAF may define a ping-pong problem based on the number of times a handover is repeated between two cells.

[0148] In various embodiments, NWDAF may define a connection failure based on the number of connection failures of a terminal per unit time, or based on the average time taken until re-establishment. Additionally, NWDAF may define a connection failure based on the ratio of cases where failed cells and re-established cells are different.

[0149] In various embodiments, terminal failure can be defined by considering traffic information. For example, since user inconvenience is significant when a terminal is interrupted while using meaningful traffic, NWDAF can analyze terminal failure by considering the history of the terminal's traffic.

[0150] In various embodiments, the NWDAF may receive information related to the history of the terminal based on the minimization of drive test (MDT). The MDT may refer to physically collecting data using a vehicle or equipment (such as a terminal) to measure the quality of a communication network, and the collected data related to the history of the terminal may be transmitted to the NWDAF. The information related to the history of the terminal may be referred to as MDT data.

[0151] NWDAF can determine the failure path of a terminal regarding failures that the terminal repeatedly experiences based on information related to the terminal's history. For example, if a terminal experiences a failure in Cell C while moving in the order of Cell A, Cell B, and Cell C, and that failure occurs repeatedly when the terminal moves along the same path, NWDAF can analyze that the same problem recurs when the terminal moves along a specific path based on information related to the terminal's history, and can identify the terminal's path that causes the recurring failures.

[0152] Specifically, the NWDAF can determine the path of a terminal related to a terminal failure through information related to the terminal's history. For example, the NWDAF can generate information to identify the terminal experiencing the failure (e.g., a terminal identifier), the failure path of the terminal related to the failure, and information regarding the type of failure. In this case, the terminal's path may represent the terminal's cell trajectory or cell signal pattern. The NWDAF can generate a cell signal pattern related to the terminal's failure. For example, regarding repeated terminal failures, the NWDAF can generate a representative cell signal pattern based on multiple cell-related signal patterns measured in the relevant cell immediately before the terminal experiences the failure. The representative cell signal pattern can be compared with cell signal patterns measured by the terminal subsequently to identify whether the terminal is moving along a path where it may experience failure. Since the cell trajectory or cell signal pattern related to the terminal's failure generated by the NWDAF specifies a single failure path based on the terminal's history information repeatedly received by the NWDAF, it may be referred to as a representative cell trajectory or a representative cell signal pattern.

[0153] In various embodiments, the NWDAF may output information regarding the terminal associated with the failure, the failure path of the terminal, the type of failure, and / or the cell signal pattern associated with the failure, based on an artificial intelligence model from the collected information. The information output from the NWDAF is transmitted to a base station and can be used by the base station to identify the path along which the terminal is moving.

[0154] In step 814, the terminal may be connected to a cell operated by the second base station. For example, the terminal may be connected to the second base station by camping on the second base station, or based on a handover, cell selection, or cell reselection operation. The cell operated by the second base station may be a cell associated with the terminal's failure path.

[0155] In step 816, the NWDAF may transmit information for identifying the terminal, the terminal's failure path related to the terminal's failure, and information regarding the terminal's failure type to the second base station via the AMF. Step 816 may be triggered by the terminal connecting to a cell operated by the second base station. For example, when the NWDAF recognizes that the terminal is connected to a cell operated by the second base station, the NWDAF may identify that the cell is included in the terminal's failure path and transmit information for terminal-based configuration to the second base station via the AMF. Although the transmission and reception operations between the NWDAF and the AMF are omitted in FIG. 8, operations may be included for transmitting and receiving a message to indicate that the terminal is connected to a cell included in the failure path, or for transmitting and receiving a message containing information for tracking the terminal's path (such as terminal identifier, failure path, and information regarding the failure type).

[0156] When a terminal is connected to a path (or cell) associated with the terminal's failure, the NWDAF may transmit information to a second base station operating the cell to which the terminal is connected (e.g., terminal identifier), the terminal's failure path associated with the terminal's failure (e.g., cell trajectory or cell signal pattern), and information regarding the type of terminal's failure via the AMF so that the terminal can track whether the terminal is moving along the failure path. Based on the received information, the second base station can identify the terminal connected to the cell and track whether the identified terminal is moving along the failure path.

[0157] In various embodiments, when information is transmitted from the NWDAF to the base station via the AMF, the information transmitted from the AMF to the base station may be included in an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message. The INITIAL CONTEXT SETUP REQUEST message represents a message for setting the initial context of the terminal, and the UE CONTEXT MODIFICATION REQUEST message represents a message for updating context information or settings related to the terminal. The PATH SWITCH REQUEST ACKNOWLEDGE message is a message transmitted in response to the PATH SWITCH REQUEST message and may be used to notify the base station that a new path has been established after the terminal's handover.

[0158] In step 818, the second base station may receive from the terminal information regarding the cell to which the terminal is connected and / or a cell signal pattern measured by the terminal. The cell signal pattern may include a pattern for RSRP or a pattern for RSRQ measured by the terminal, and may include measurements for the serving cell and neighboring cells. The cell signal pattern received by the second base station from the terminal may be compared with a representative cell signal pattern received by the second base station from the NWDAF to identify whether the terminal is moving along a failure path.

[0159] In various embodiments, the second base station may transmit a message to the terminal requesting measurement of a cell signal. At this time, the second base station may set the measurement period of the cell signal, etc., to the terminal. For example, the first base station may set the terminal to measure the cell signal at a period of 120ms. In addition, the first base station may set a period of 40ms, 64ms, 80ms, or 100ms, etc., to the terminal for determining whether the conditions of Event A1 are satisfied in relation to Event A1 measurement. The second base station may separately request the terminal to measure the cell signal in order to track the terminal's path.

[0160] In step 820, the second base station can track the movement path of the terminal. Based on the information received in step 816 and the information regarding the cell trajectory the terminal actually moved, the second base station can identify whether the terminal is moving along a failure path. The information regarding the cell trajectory the terminal actually moved along may include the history of the cells to which the terminal is connected and the period during which the terminal was connected to each cell. The information regarding the cell trajectory the terminal actually moved along may be referred to as UE History Information. UE History Information is managed by the base station to which the terminal is connected and may be transmitted between base stations (or via AMF) when the terminal moves between base stations.

[0161] For example, the second base station can determine whether the path of the cell the terminal moved to matches the cell trajectory information received in step 816.

[0162] In various embodiments, if the failure path of the terminal includes a cell of the second base station but the failure of the terminal does not occur in the cell of the second base station, the operation of the second base station receiving a cell signal pattern (e.g., 818 operation) may be omitted. That is, the second base station may not request a cell signal pattern from the terminal. Additionally, the operation of the second base station calculating a similarity based on the cell signal pattern to track the terminal's path may be omitted.

[0163] That is, the operation of tracking the terminal's path based on the terminal's cell signal pattern can be performed when the terminal is connected to a specific cell where failure is expected. For example, if the terminal's failure path consists of Cell A, Cell B, and Cell C, and the terminal's failure is expected to occur in Cell C, and Cells A and B are operated by the second base station while Cell C is operated by the first base station, then when the terminal is connected to Cell A or Cell B, the second base station does not track the terminal based on the cell signal pattern, but when the terminal is connected to Cell C, the first base station can track the terminal based on the cell signal pattern.

[0164] In various embodiments, the base station may select a cell to perform a similarity determination of cell signal patterns based on the time the terminal maintains a connection to the cell. Since it may be expected that the time the terminal maintains a connection in a cell where terminal failure is anticipated will be very short, the base station may request and collect the terminal's cell signal patterns starting from the cell immediately preceding it.

[0165] In step 822, the terminal may be connected to a cell operated by the first base station. For example, the terminal may be connected to the first base station by camping on the first base station, or by a handover, reestablish, cell selection, or cell reselection operation. The cell operated by the first base station may be a cell associated with the terminal's failure path.

[0166] In step 824, the second base station may transmit to the first base station information for identifying the terminal (e.g., terminal identifier), information regarding the cell trajectory associated with the failure, and information regarding the cell signal pattern associated with the failure. That is, the second base station may transmit to the first base station the information received from the NWDAF in operation 816. Operation 824 may be triggered by the terminal connecting to a cell operated by the first base station. For example, if the terminal connects to a cell operated by the first base station when the cell operated by the first base station is included in the terminal's failure path, the second base station may transmit information related to the terminal's failure path to the first base station. However, if the cell operated by the first base station is not related to the terminal's failure path, the second base station may not transmit information related to the terminal's failure path to the first base station even if the terminal connects to a cell operated by the first base station.

[0167] Step 824 can be performed based on an Xn interface between base stations. Specifically, the second base station may transmit to the first base station information for identifying the terminal (e.g., terminal identifier) ​​and information about the terminal's failure path, such as information about a representative cell trajectory and a representative cell signal pattern, through a HANDOVER REQUEST message or a RETRIEVE UE CONTEXT RESPONSE.

[0168] In step 826, the NWDAF may transmit information to the first base station via the AMF for identifying the terminal, the terminal's failure path related to the terminal's failure, and information regarding the terminal's failure type. Step 826 may be triggered by the terminal connecting to a cell operated by the first base station. For example, when the NWDAF recognizes that the terminal is connected to a cell operated by the first base station, the NWDAF may identify that the cell is included in the terminal's failure path and transmit information for terminal-based configuration to the first base station via the AMF. The description of step 826 may correspond to the description of step 816 described above.

[0169] In various embodiments, either step 824 or step 826 may be omitted. That is, the first base station may receive information from the NWDAF via the AMF or receive information from the second base station.

[0170] In step 828, the first base station may receive from the terminal information regarding the cell to which the terminal is connected and / or a cell signal pattern measured by the terminal. The cell signal pattern may include a pattern for RSRP or a pattern for RSRQ measured by the terminal, and may include measurements for the serving cell and neighboring cells. In various embodiments, the first base station may transmit a message to the terminal to request a measurement of the cell signal. At this time, the first base station may set the measurement period of the cell signal, etc., for the terminal. For example, the first base station may set the terminal to measure the cell signal at a period of 120ms. Additionally, the first base station may set a period for determining whether the conditions of Event A1 are satisfied, such as 40ms, 64ms, 80ms, or 100ms, in relation to Event A1 measurement. The first base station may separately request the terminal to measure the cell signal to track the terminal's path.

[0171] In step 830, the first base station can track the movement path of the terminal. Based on the information received in step 824 or 826 and the information regarding the cell trajectory the terminal actually moved, the first base station can identify whether the terminal is moving along a failure path. The information regarding the cell trajectory the terminal actually moved along may include the history of the cells to which the terminal is connected and the period during which the terminal was connected to each cell. The information regarding the cell trajectory the terminal actually moved along may be referred to as UE History Information. UE History Information is managed by the base station to which the terminal is connected and may be transmitted between base stations (or via AMF) when the terminal moves between base stations.

[0172] For example, the first base station can determine whether the path of the cell the terminal moved to matches the cell trajectory information received in step 828.

[0173] In step 832, the first base station can identify whether the terminal is moving along a failure path within the cell by comparing the cell signal pattern received from the terminal in step 828 with the representative cell signal pattern received in step 824 or 826. Specifically, the comparison of cell signal patterns can be performed by determining the similarity between the cell signal patterns. The first base station derives the similarity between the terminal's cell signal pattern and the cell signal pattern of the failure path based on an artificial intelligence model or other algorithm, and can determine that the terminal is moving along the failure path if the similarity is greater than or equal to a specific threshold. On the other hand, if the similarity between the cell signal patterns is less than a specific threshold, the first base station can determine that the terminal is not moving along the failure path.

[0174] In various embodiments, the base station may select a cell to perform a similarity determination of cell signal patterns based on the time the terminal has maintained a connection to the cell. For example, if the time the terminal has maintained a connection to the cell is less than a specific threshold, the base station may not use the cell signal pattern measured by the terminal in that cell for similarity calculation, but may use the cell signal pattern measured in the cell to which the terminal was previously connected.

[0175] In step 834, if the first base station determines that the terminal is moving along a failure path, the first base station may transmit terminal-based configuration information to the terminal. That is, the first base station may transmit appropriate configuration information to the terminal so that the terminal does not experience a failure. The first base station may transmit configuration information to the terminal to prevent the terminal from experiencing the failure based on information regarding the type of failure among the information received in step 824 or 826.

[0176] In various embodiments, if the failure type received in step 824 or step 826 indicates a frequent handover of the terminal, the first base station may transmit terminal-based configuration information to the terminal so that the terminal can hand over to a cell that services a wide range. The handover may include an inter-frequency handover or an inter-RAT (radio access technology) handover.

[0177] In various embodiments, if the failure type received in step 824 or step 826 indicates a ping-pong (repeated handover between two cells) of the terminal, the first base station may transmit to the terminal configuration information in which the cell individual offset (CIO) is adjusted so that the terminal does not easily perform a handover to another cell. The CIO may represent information for adjusting the evaluation of signal quality regarding a cell. Thus, through the adjusted CIO, the evaluation of signal quality regarding a cell is adjusted so that the handover of the terminal to a specific cell can be suppressed.

[0178] In various embodiments, if the failure type received in step 824 or step 826 indicates a terminal's repeated connection failure or a long time until re-establishment, indicating difficulty in connecting to a specific cell, the first base station may transmit configuration information to the terminal in which the cell is excluded from candidate cells so that the terminal does not attempt to connect to the cell.

[0179] In the embodiments of the present disclosure, the failure types of the terminal are not limited to those described above, and various failure types may be set according to the definition of failure, and various terminal-based configuration information to prevent such failure types may be applied. Even if specific names of configuration parameters are not designated in the embodiments of the present disclosure, adjustments to configuration parameters within the range applicable by a person skilled in the art may be understood as described in the present disclosure.

[0180] In step 836, the terminal can apply the terminal-based configuration information received in step 834. Therefore, even if the terminal moves in a manner similar to the failure path, the expected failure can be prevented in advance by applying terminal-based configuration information (or terminal-specific configuration information) instead of cell-based configuration information.

[0181] The operations of the embodiments described in FIG. 8 may be changed in order, some operations may be omitted, separate operations may be merged to perform a single operation, or a single operation may be performed separately. Additionally, the operations of the embodiments described in FIG. 8 may be combined with operations of other embodiments described in the present disclosure to form new embodiments. Embodiments according to variations and combinations of the embodiments of the present disclosure may be understood as described by the present disclosure to the extent that they are derivable by a person skilled in the art.

[0182] FIG. 9 illustrates a method for terminal-based configuration according to embodiments of the present disclosure.

[0183] Referring to FIG. 9, the operation of a network data analytics function (NWDAF), an access and mobility management function (AMF), a first base station, and a terminal for terminal-based configuration is illustrated. The NWDAF may correspond to the core network of FIG. 5, and the first base station may correspond to the RAN of FIG. 5. The terminal may correspond to the terminal of FIG. 2, and the NWDAF, AMF, or the first base station may correspond to the network entity of FIG. 3.

[0184] The embodiment of FIG. 9 may show the operations performed by each entity for terminal-based configuration when a terminal moves between multiple cells (e.g., A and B) operated by a single base station.

[0185] In step 912, the NWDAF may receive information related to the terminal's history. Information related to the terminal's history may include information about the terminal's path, i.e., the cell trajectory to which the terminal is connected, and information about the terminal's failures and / or traffic information. Information about the cell trajectory may indicate the cells to which the terminal is connected in order and may include information about the time the connection to the cell was maintained. The cells may be indicated by cell identifiers. Information about failures may indicate information about the type of failure experienced by the terminal. For example, failures may include the terminal's frequent handovers, ping-pong issues, or connection failure issues. Connection failure issues may include connection failures or re-establishment failures for specific cells. The NWDAF may identify which failures the terminal has experienced by receiving information indicating the type of failure experienced by the terminal or by receiving information related to the terminal's failures.

[0186] Additionally, the NWDAF can receive information regarding cell signal patterns measured by the terminal. For example, the NWDAF can receive information regarding cell signal patterns, such as RSRP (reference signal received power) or RSRQ (reference signal received quality), measured by the terminal. The cell signal pattern may include continuous measurement values ​​for the terminal's serving cell or neighboring cells. The signal pattern for the serving cell or neighboring cells measured by the terminal while moving may take on a specific form depending on the terminal's movement path. A sequence of measurement values ​​for the serving cell and neighboring cells continuously measured by the terminal over a specific period of time may correspond to the terminal's movement path. Therefore, the terminal's movement path and the cell signal pattern measured by the terminal may correspond to each other, and the measured signal pattern may be understood as information representing the terminal's movement path.

[0187] Information regarding the failure of a terminal may indicate the type of failure experienced by the terminal, or may indicate relevant information capable of analyzing or identifying the type of failure experienced by the terminal. The failure of the terminal may include frequent handovers, ping-pong, or connection failures. However, the failure of the terminal is not limited to the aforementioned cases and may include various additional cases.

[0188] In various embodiments, NWDAF may define frequent handover based on the number of terminal handovers per unit time, or define frequent handover based on the average connection maintenance time per cell. Additionally, NWDAF may define a ping-pong problem based on the number of times a handover is repeated between two cells.

[0189] In various embodiments, NWDAF may define a connection failure based on the number of connection failures of a terminal per unit time, or based on the average time taken until re-establishment. Additionally, NWDAF may define a connection failure based on the ratio of cases where failed cells and re-established cells are different.

[0190] In various embodiments, terminal failure can be defined by considering traffic information. For example, since user inconvenience is significant when a terminal is interrupted while using meaningful traffic, NWDAF can analyze terminal failure by considering the history of the terminal's traffic.

[0191] In various embodiments, the NWDAF may receive information related to the history of the terminal based on the minimization of drive test (MDT). The MDT may refer to physically collecting data using a vehicle or equipment (such as a terminal) to measure the quality of a communication network, and the collected data related to the history of the terminal may be transmitted to the NWDAF. The information related to the history of the terminal may be referred to as MDT data.

[0192] NWDAF can determine the failure path of a terminal regarding failures that the terminal repeatedly experiences based on information related to the terminal's history. For example, if a terminal experiences a failure in Cell C while moving in the order of Cell A, Cell B, and Cell C, and that failure occurs repeatedly when the terminal moves along the same path, NWDAF can analyze that the same problem recurs when the terminal moves along a specific path based on information related to the terminal's history, and can identify the terminal's path that causes the recurring failures.

[0193] Specifically, the NWDAF can determine the path of a terminal related to a terminal failure through information related to the terminal's history. For example, the NWDAF can generate information to identify the terminal experiencing the failure (e.g., a terminal identifier), the failure path of the terminal related to the failure, and information regarding the type of failure. In this case, the terminal's path may represent the terminal's cell trajectory or cell signal pattern. The NWDAF can generate a cell signal pattern related to the terminal's failure. For example, regarding repeated terminal failures, the NWDAF can generate a representative cell signal pattern based on multiple cell-related signal patterns measured in the relevant cell immediately before the terminal experiences the failure. The representative cell signal pattern can be compared with cell signal patterns measured by the terminal subsequently to identify whether the terminal is moving along a path where it may experience failure. Since the cell trajectory or cell signal pattern related to the terminal's failure generated by the NWDAF specifies a single failure path based on the terminal's history information repeatedly received by the NWDAF, it may be referred to as a representative cell trajectory or a representative cell signal pattern.

[0194] In various embodiments, the NWDAF may output information regarding the terminal associated with the failure, the path of the terminal, the type of failure, and / or the cell signal pattern associated with the failure, based on an artificial intelligence model from the collected information. The information output from the NWDAF is transmitted to a base station and can be used by the base station to identify the path the terminal is traveling.

[0195] In step 914, the terminal may be connected to cell A operated by the first base station. For example, the terminal may be connected to the first base station by camping on the first base station, or by a handover, cell selection, or cell reselection operation. Cell A operated by the first base station may be a cell associated with the terminal's failure path.

[0196] In step 916, the NWDAF may transmit information for identifying the terminal, the terminal's failure path (cell trajectory or cell signal pattern, etc.) related to the terminal's failure, and information regarding the terminal's failure type to the first base station via the AMF. Step 916 may be triggered by the terminal being connected to cell A operated by the first base station. For example, when the NWDAF recognizes that the terminal is connected to a cell operated by the first base station, the NWDAF may identify that the cell is included in the terminal's failure path and transmit information for terminal-based configuration to the first base station via the AMF. Although the transmission and reception operations between the NWDAF and the AMF are omitted in FIG. 9, operations may be included for transmitting and receiving a message to indicate that the terminal is connected to a cell included in the failure path, or for transmitting and receiving a message containing information for tracking the terminal's path (terminal identifier, failure path, and information regarding the failure type, etc.).

[0197] When a terminal is connected to a path (or cell) associated with the terminal's failure, the NWDAF can transmit information to a first base station operating the cell to which the terminal is connected (e.g., terminal identifier), the terminal's failure path associated with the terminal's failure (e.g., cell trajectory or cell signal pattern), and information regarding the type of failure of the terminal via the AMF so that the terminal can track whether the terminal is moving along the failure path. Based on the received information, the first base station can identify the terminal connected to the cell and track whether the identified terminal is moving along the failure path.

[0198] In various embodiments, when information is transmitted from the NWDAF to the base station via the AMF, the information transmitted from the AMF to the base station may be included in an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message. The INITIAL CONTEXT SETUP REQUEST message represents a message for setting the initial context of the terminal, and the UE CONTEXT MODIFICATION REQUEST message represents a message for updating context information or settings related to the terminal. The PATH SWITCH REQUEST ACKNOWLEDGE message is a message transmitted in response to the PATH SWITCH REQUEST message and may be used to notify the base station that a new path has been established after the terminal's handover.

[0199] In step 918, the first base station can track the path of the terminal based on the information received in step 916. That is, the first base station can monitor which cell the terminal is connected to or how the terminal is moving.

[0200] In step 920, the terminal may be connected to Cell B operated by the first base station. For example, the terminal may be connected to the first base station by camping on the first base station, or by a handover, cell selection, or cell reselection operation. Cell B operated by the first base station may be a cell associated with the terminal's failure path.

[0201] The first base station can identify that the terminal has moved from cell A to cell B, and can identify that the terminal has moved along a failure path based on information about the cell trajectory received in step 916.

[0202] In step 922, if cell B is a cell where failure of the terminal is expected, the first base station may request the terminal to measure the cell signal pattern when the terminal is connected to cell B. That is, the measurement of the cell signal pattern may be requested when the terminal is connected to a cell where failure is expected. Therefore, when the terminal is connected to cell A, the first base station does not request the terminal to measure the cell signal pattern, but when the terminal is connected to cell B, the first base station may request the terminal to measure the cell signal pattern.

[0203] In step 924, the first base station may receive from the terminal information regarding the cell to which the terminal is connected and / or a cell signal pattern measured by the terminal. The cell signal pattern may include a pattern for RSRP or a pattern for RSRQ measured by the terminal, and may include measurements for the serving cell and neighboring cells. The cell signal pattern received by the first base station from the terminal may be compared with a representative cell signal pattern received by the first base station from the NWDAF to identify whether the terminal is moving along a failure path.

[0204] In various embodiments, the first base station may transmit a message to the terminal requesting measurement of a cell signal. At this time, the first base station may set the measurement period or measurement time of the cell signal to the terminal. For example, the first base station may set the terminal to measure the cell signal at a period of 120ms. Additionally, the first base station may set a period of 40ms, 64ms, 80ms, or 100ms, etc., to determine whether the conditions of Event A1 are satisfied in relation to Event A1 measurement. The first base station may separately request the terminal to measure the cell signal in order to track the terminal's path.

[0205] In step 926, the first base station can identify whether the terminal is moving along a failure path within the cell by comparing the cell signal pattern received from the terminal in step 924 with the representative cell signal pattern received from the NWDAF in step 916. Specifically, the comparison of cell signal patterns can be performed by determining the similarity between the cell signal patterns. The first base station derives the similarity between the terminal's cell signal pattern and the cell signal pattern of the failure path based on an artificial intelligence model or other algorithm, and can determine that the terminal is moving along the failure path if the similarity is greater than or equal to a specific threshold. On the other hand, if the similarity between the cell signal patterns is less than a specific threshold, the first base station can determine that the terminal is not moving along the failure path.

[0206] In various embodiments, the base station may derive the similarity of cell signal patterns based on the time the terminal maintained a connection to the cell. For example, if the time the terminal maintained a connection to the cell is less than a specific threshold, the base station may not use the cell signal pattern measured by the terminal in that cell for the similarity calculation, but may use the cell signal pattern measured in the cell to which the terminal was previously connected.

[0207] In step 928, if the first base station determines that the terminal is moving along a failure path, the first base station may transmit terminal-based configuration information to the terminal. That is, the first base station may transmit appropriate configuration information to the terminal so that the terminal does not experience a failure. Based on the information regarding the type of failure among the information received in step 916, the first base station may transmit configuration information to the terminal to prevent the terminal from experiencing the corresponding failure.

[0208] In various embodiments, if the failure type received in step 916 indicates a frequent handover of the terminal, the first base station may transmit terminal-based configuration information to the terminal so that the terminal can hand over to a cell that services a wide range. The handover may include an inter-frequency handover or an inter-RAT (radio access technology) handover.

[0209] In various embodiments, if the failure type received in step 916 indicates a terminal's ping-pong (repeated handover between two cells), the first base station may transmit to the terminal configuration information in which the cell individual offset (CIO) is adjusted so that the terminal does not easily perform a handover to that cell. The CIO may represent information for adjusting the evaluation of signal quality regarding the cell. Thus, through the adjusted CIO, the evaluation of signal quality regarding the cell is adjusted so that the terminal's handover to a specific cell can be suppressed.

[0210] In various embodiments, if the failure type received in step 916 indicates a terminal's repeated connection failure or a long time until re-establishment, indicating difficulty in connecting to a specific cell, the first base station may transmit configuration information to the terminal to exclude the cell from candidate cells so that the terminal does not attempt to connect to the cell.

[0211] In the embodiments of the present disclosure, the failure types of the terminal are not limited to those described above, and various failure types may be set according to the definition of failure, and various terminal-based configuration information to prevent such failure types may be applied. Even if specific names of configuration parameters are not designated in the embodiments of the present disclosure, adjustments to configuration parameters within the range applicable by a person skilled in the art may be understood as described in the present disclosure.

[0212] In step 930, the terminal can apply the terminal-based configuration information received in step 928. Therefore, even if the terminal moves in a manner similar to a failure path, the expected failure can be prevented in advance by applying terminal-based configuration information (or terminal-specific configuration information) instead of cell-based configuration information.

[0213] The operations of the embodiment described in FIG. 9 may be changed in order, some operations may be omitted, operations shown separately may be merged into a single operation, or operations shown as a single operation may be performed separately. Additionally, the operations of the embodiment described in FIG. 9 may be combined with operations of other embodiments described in the present disclosure to form new embodiments. Embodiments according to variations and combinations of the embodiments of the present disclosure may be understood as described by the present disclosure to the extent that they are derivable by a person skilled in the art.

[0214] FIG. 10 shows an example of information for terminal-based configuration according to embodiments of the present disclosure.

[0215] Referring to FIG. 10, information transmitted from an NWDAF or another base station to a base station is illustrated. In FIG. 10, UE level opt selected and UE level opt information may be included in a message transmitted from the NWDAF to the base station via the AMF, or may be included in a message based on the Xn interface between base stations. Specifically, UE level opt selected and UE level opt information may be transmitted by being included in messages transmitted from the AMF to the base station, such as the INITIAL CONTEXT SETUP REQUEST message, the INITIAL CONTEXT SETUP REQUEST message, or the PATH SWITCH REQUEST ACKNOWLEDGE. Additionally, UE level opt selected and UE level opt information may be transmitted by being included in messages transmitted based on the Xn interface, such as the HANDOVER REQUEST message or the RETRIEVE UE CONTEXT RESPONSE message.

[0216] UE level opt selected may indicate whether terminal-based settings (or terminal-specific settings) are applied. If UE level opt selected is present, UE level opt information is included in the message, and UE level opt information includes information for tracking the terminal for terminal-based settings and information regarding the terminal's failure type.

[0217] UE level opt information may include problem type, trajectory where the problem occurs, or measurement sequence.

[0218] Problem type may indicate a type of failure of the terminal. For example, it may indicate problems such as frequent handovers, ping-pong handovers, and connection failures. The types of failure are not limited to those described above and may be defined more specifically or more comprehensively.

[0219] "Trajectory where the problem occurs" represents information about the path where the terminal experiences failure and may include cell information. Cell information may represent a cell trajectory associated with the path where the terminal experiences failure. For example, cell information may be information that can identify the cell to which the terminal is connected and the time during which the connection between the terminal and the cell was maintained in sequence. In this case, the cell trajectory may include a cell identifier. Cell information may be specified in FIG. 11.

[0220] The measurement sequence may represent information about cell signal patterns. For example, it may represent the sequence of RSRP or RSRQ for a serving cell or neighboring cell. The measurement sequence may include measurement information, which may be specified in FIG. 12.

[0221] According to an embodiment of the present disclosure, a base station can perform tracking of a terminal based on the information of FIG. 10, and if it identifies that the terminal is following a failed path, it can perform terminal-based configuration.

[0222] FIG. 11 shows an example of information for terminal-based configuration according to embodiments of the present disclosure.

[0223] Specifically, FIG. 11 illustrates specific information regarding the cell information of FIG. 10.

[0224] Referring to FIG. 11, FIG. 11 may include information about an NG-RAN cell or an E-UTRAN cell. An NG-RAN cell may represent information about a cell of a 5G NR (new radio) network, and an E-UTRAN cell may represent information about a cell of an LTE (long term evolution) network.

[0225] NG-RAN Cell information or E-UTRAN Cell information may include a cell identifier (e.g., cell global identifier, CGI) as information for identifying a cell.

[0226] Time UE Stayed in Cell can indicate the length of time the terminal is connected to the cell. In other words, it can indicate the duration during which the terminal is connected to the cell.

[0227] Problem occurrence can indicate whether it is a cell where terminal failure is expected to occur.

[0228] Based on NG-RAN cell information, time UE stays in cell and / or problem occurrence, the base station can identify cell trajectories, the duration for which a terminal is connected to each cell, and cells where terminal failure is expected.

[0229] Therefore, the Cell information in Fig. 11 can represent information about the cell trajectory related to the failure of the terminal.

[0230] In various embodiments, the information regarding the cell trajectory may include information regarding at least three or more cells.

[0231] In various embodiments, the names of the parameters described in FIG. 11 are not limited to the illustrated names and may be referred to by various terms depending on the meaning and / or use of the parameters.

[0232] FIG. 12 shows an example of information for terminal-based configuration according to embodiments of the present disclosure.

[0233] Specifically, FIG. 12 illustrates specific details regarding the Measurement information of FIG. 10.

[0234] Referring to FIG. 12, the measurement information may include an RSRP serving and an RSRP neighbor list for the RSRP. Also, the measurement information may include an RSRQ serving and an RSRQ neighbor list for the RSRQ.

[0235] RSRP serving may represent an RSRP value associated with the terminal's serving cell. The RSRP value may include a continuous pattern or sequence.

[0236] The RSRP neighbor list may include identifiers for neighbor cells of the terminal (e.g., neighbor cell identity) and RSRP values ​​for neighbor cells (e.g., RSRP neighbor).

[0237] RSRQ serving can represent an RSRQ value associated with the terminal's serving cell. The RSRQ value may include a continuous pattern or sequence.

[0238] The RSRQ neighbor list may include identifiers for neighbor cells of the terminal (e.g., neighbor cell identity) and RSRQ values ​​for neighbor cells (e.g., RSRQ neighbor).

[0239] Therefore, the measurement information of Fig. 12 can represent the pattern of cell signals related to terminal failure.

[0240] In various embodiments, the cell signal pattern may include a pattern or sequence for at least one of RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), or SINR (signal to interference plus noise ratio).

[0241] FIG. 13 shows an example of a cell path history of a terminal according to embodiments of the present disclosure.

[0242] Referring to FIG. 13, the cell trajectory of the terminal is illustrated in sequence. The terminal may be connected to cell A for 600 seconds, to cell B for 100 seconds, to cell C for 50 seconds, and then to cell B again for 50 seconds. Additionally, the terminal may be connected to cell D for 20 seconds and to cell E for 300 seconds. As the terminal moves along this path, the terminal may repeatedly experience failure at cell D. Here, cells A, B, and C can be assumed to be cells operated by the first base station, and cells D and E can be assumed to be cells operated by the second base station.

[0243] The history of repeated failures of the terminal in Cell D is transmitted to NWDAF, and NWDAF can derive the terminal's failure path based on the collected history information. At this time, the terminal's failure path may include information about the terminal's cell trajectory and cell signal patterns.

[0244] When a terminal connects to Cell A, and it is identified that the terminal is connected to a failure path, the NWDAF may transmit information regarding the terminal's identifier, the terminal's failure path, and the failure type to the first base station via the AMF. Based on the received information, the first base station may track whether the identified terminal is moving along the failure path. If the terminal moves along the failure path through the cells (A, B, C) operated by the first base station, and subsequently moves to a cell (e.g., Cell D) operated by the second base station, the first base station may transmit information regarding the terminal's identifier, the terminal's failure path, and the failure type to the second base station. Alternatively, the second base station may receive information regarding the terminal's identifier, the terminal's failure path, and the failure type from the NWDAF via the AMF. Consequently, even if the base station providing the serving cell to the terminal changes, tracking of the terminal can be continuously performed by the changed base station.

[0245] Based on the received information, the second base station can anticipate that a terminal connected to Cell D has been moving along a failure path and that a failure of the terminal may occur in Cell D. The second base station can determine how the terminal connected to Cell D is moving within Cell D based on the cell signal pattern. The second base station can identify whether the terminal is moving along a failure path based on the similarity between the cell signal pattern received from the terminal and the cell signal pattern received from the first base station or the NWDAF. If it is determined that the terminal is moving along a failure path in Cell D, the second base station can anticipate that the terminal will fail and perform terminal-based configuration. On the other hand, if it is determined that the terminal is not moving along a failure path in Cell D, the second base station can maintain the existing cell-based configuration.

[0246] In various embodiments, when determining similarity for cell signal patterns, the base station may consider the length of time the terminal is currently connected to the cell. For example, if the length of time the terminal is connected to the cell (e.g., stay time) is less than an arbitrary threshold, the cell signal pattern measured by the terminal in that cell may not be considered for similarity determination. The base station may refer to the cell signal pattern measured by the terminal in the previous cell for similarity determination. On the other hand, if the length of time the terminal is connected to the cell is greater than or equal to an arbitrary threshold, the base station may consider the cell signal pattern measured by the terminal in that cell for similarity determination.

[0247] For example, in FIG. 13, if the time the terminal is connected to cell D is 20 seconds and 20 seconds is less than the threshold, the base station does not consider the cell signal pattern measured by the terminal in cell D for similarity determination, but may consider the cell signal pattern measured by the terminal in cell C for similarity determination.

[0248] FIG. 14 illustrates the operation of a base station according to embodiments of the present disclosure.

[0249] Referring to FIG. 14, the operation of a base station for terminal-based configuration is illustrated. The base station may correspond to the RAN of FIG. 5 or to the base station of FIG. 6 through FIG. 8. The base station may correspond to the network entity of FIG. 3.

[0250] Referring to FIG. 14, in step 1412, a base station may receive a first message comprising first information for identifying a terminal, second information regarding a cell trajectory, third information regarding a signal pattern associated with a cell, and fourth information indicating a type of failure. The first information may include a terminal identifier, the second information may include cell information regarding the failure path of the terminal, and the third information may include a cell signal pattern regarding the failure path. Additionally, the first message may include a message transmitted from the NWDAF via the AMF or a message based on the Xn interface from another base station.

[0251] Step 1412 may correspond to Step 716 of FIG. 7, Step 816 of FIG. 8, Step 824 or Step 826 of FIG. 9, and Step 916 of FIG. 9. Additionally, Step 1412 may be triggered by a terminal connecting to a cell operated by a base station.

[0252] In step 1414, the base station can identify whether the terminal is moving along the failure path based on the first information and the second information. That is, the base station can identify the terminal based on the first information and identify whether the identified terminal is moving along the failure path based on the second information.

[0253] Step 1414 can correspond to Step 720 of FIG. 7, Step 820 or Step 830 of FIG. 8, and Step 918 of FIG. 9.

[0254] In step 1416, the base station can identify that the cell signal pattern received from the terminal and the cell signal pattern of the third information related to the failure path are similar.

[0255] Step 1416 can correspond to Step 722 of FIG. 7, Step 832 of FIG. 8, or Step 926 of FIG. 9.

[0256] In step 1418, the base station may transmit a second message containing terminal-based configuration information to the terminal identified based on the fourth information.

[0257] Step 1418 can correspond to Step 724 of FIG. 7, Step 834 of FIG. 8, or Step 928 of FIG. 9.

[0258] FIG. 15 illustrates the operation of a network entity according to embodiments of the present disclosure.

[0259] Referring to FIG. 15, the operation of NWDAF for terminal-based configuration is illustrated. NWDAF can correspond to the core network of FIG. 5 and can correspond to the network entity of FIG. 3.

[0260] In step 1512, NWDAF can receive first information about the cell trajectory of the terminal, second information about the signal pattern associated with the cell, and third information about the failure of the terminal.

[0261] Step 1512 can correspond to Step 712 of FIG. 7, Step 812 of FIG. 8, or Step 912 of FIG. 9.

[0262] In step 1514, NWDAF may generate, based on the first information, the second information, and the third information, fourth information indicating a representative cell trajectory for a terminal failure, fifth information indicating a representative cell signal pattern for a failure, and sixth information indicating a type of failure. Here, the fourth information, the fifth information, and / or the sixth information may be generated based on the operation of an artificial intelligence model.

[0263] In step 1516, NWDAF can transmit the fourth information, fifth information, and sixth information to the base station connected to the terminal expected to fail.

[0264] Step 1516 may correspond to Step 716 of FIG. 7, Step 816 or Step 826 of FIG. 8, or Step 916 of FIG. 9.

[0265] Meanwhile, a method performed by a first base station in a wireless communication system according to embodiments of the present disclosure may include: receiving a first message comprising first information for identifying a terminal, second information regarding a cell trajectory, third information regarding a cell-related signal pattern, and fourth information indicating a type of failure; identifying that the terminal is moving along a cell trajectory based on the first information and the second information; identifying that the signal pattern received from the terminal and the signal pattern of the third information are similar; and transmitting a second message to the terminal comprising setting information for preventing failure of the terminal based on the fourth information.

[0266] In one embodiment, the first message is received from the NWDAF (network data analytics function) entity via the AMF (access and mobility management function) entity, and the first message may include any one of an INITIAL CONTEXT SETUP message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message.

[0267] In one embodiment, the first message is received from the second base station based on the Xn interface, and the first message may include either a HANDOVER REQUEST message or a RETRIEVE UE CONTEXT RESPONSE message.

[0268] In one embodiment, the failure type of the terminal includes a first type indicating frequent cell changes, a second type indicating repetitive handover between two cells, or a third type indicating connection failure. If the failure type is the first type, the configuration information may include configuration information for moving the terminal to a specific cell. If the failure type is the second type, the configuration information includes fifth information for adjusting the evaluation of signal quality regarding the cell, and the fifth information may include a cell individual offset (CIO). If the failure type is the third type, the configuration information may include information for excluding a cell where a connection failure occurs from the candidate cells selectable by the terminal.

[0269] In one embodiment, the signal pattern received from the terminal may include a signal pattern measured for the terminal's serving cell and a signal pattern measured for the terminal's neighboring cell.

[0270] In one embodiment, the signal pattern received from the terminal may include a pattern for at least one of RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), or SINR (signal to interference plus noise ratio).

[0271] According to embodiments of the present disclosure, a path causing repeated failures of a terminal is analyzed and derived through a core network, and whether the terminal moves along the failure path is tracked by a base station, and terminal-based settings are performed before the terminal experiences failure, thereby having the effect of preventing failure of the terminal.

[0272] Although the embodiments of the present disclosure have been described in detail to explain the technical concept of the present disclosure, the individual operations constituting each embodiment may be changed in order or parts of which may be omitted. Accordingly, an embodiment in which the order of operations is changed or some operations are omitted may be understood as having been described by the present disclosure. Furthermore, the embodiments of the present disclosure may be modified in various ways according to the content described in the present disclosure.

[0273] Although the operations of the method according to the embodiments of the present disclosure have been described separately for each embodiment, the operations included in each embodiment may be combined with the operations of other embodiments to form new embodiments. Accordingly, embodiments in which the embodiments of the present disclosure are combined may also be understood as being described by the present disclosure.

[0274] The various embodiments of the present disclosure and the terms used therein are not intended to limit the technical features described in the present disclosure 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 items unless the relevant context clearly indicates otherwise. In the present disclosure, each of the 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 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 a component from another component and do not limit the components in any other aspect (e.g., importance or order). Where a component (e.g., the first) is referred to as "coupled" or "connected" to another component (e.g., the second), with or without the terms "functionally" or "communicationally," it means that the component may be connected to the other component directly (e.g., via a wire), wirelessly, or through a third component.

[0275] As used in this disclosure, the term "module" 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. A module may be a component formed integrally, or a minimum unit of a component or 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).

[0276] Various embodiments of the present disclosure may be implemented as software (e.g., a program) comprising one or more instructions stored in a storage medium (e.g., internal memory or external memory) readable by a machine (e.g., an electronic device). For example, a machine (e.g., a processor of an electronic device (e.g., processor (230)) may call at least one of the one or more instructions stored from the storage medium and execute it. This enables the machine to operate to perform at least one function according to at least one called instruction. 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-transitory" simply means that the storage medium is a tangible device and does not contain a signal (e.g., an EM wave), and this term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily in the storage medium.

[0277] 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., CD-ROM (compact disc read-only memory)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) 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 in a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0278] According to various embodiments, each component (e.g., module or program) of the described components may include a singular or multiple entities. According to various embodiments, one or more of the components or operations among 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 they were performed by the corresponding component among the multiple components prior to integration. According to various embodiments, operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically; one or more of the operations may be executed in a different order; omitted; or one or more other operations may be added.

[0279] Hereinafter, in FIGS. 16 to 20, further descriptions, evaluation methods, and results regarding embodiments of the present disclosure are described. The following content may be combined with the content described in FIGS. 1 to 15 in relation to the present disclosure to constitute embodiments of the present disclosure.

[0280] AI-based subscriber-level mobility optimization

[0281] Each subscriber may experience recurring service interruptions due to their individual behavioral patterns and movement paths. However, existing cell-level optimization methods, such as Self-Organizing Network (SON) functions, operate based on overall cell performance metrics. Consequently, there may be limitations in addressing issues arising from subscriber-specific paths or behavioral patterns. These subscriber-specific issues can have a significant impact on the quality of service perceived by users, extending beyond existing cell performance metrics. This disclosure proposes a method to extract recurring problem patterns experienced by individual subscribers by utilizing their historical data. This can be achieved through AI-based clustering of subscriber information related to the paths where problems occur, specifically through cell trajectories and radio signal volume measurements. Furthermore, based on the derived problem patterns, an active approach can be proposed to predict and avoid potential problems that may occur in the problematic paths. While avoidance strategies vary depending on the type of problem, they can generally be implemented through handover to an alternative frequency band. Performance evaluation can be performed in collaboration with network operators using data collected from commercial networks. This result indicates that the proposed subscriber-level optimization method can predict and solve up to 89% of recurring problems in the problem path with 94% accuracy.

[0282] 1. Introduction

[0283] Service interruptions in mobile networks can primarily occur due to wireless link failures (RLF) and handover (HO) issues. The most common HO problems include ping-pong style HO, frequent HO, too early HO, and too late HO. RLF is caused by various factors, among which the degradation of received signal quality is a common cause. To address these RLF and HO problems, self-organizing network (SON) functions can be widely used for cell-level network optimization. Specifically, Mobility Robustness Optimization (MRO) functions can minimize service interruptions caused by incorrect HO timing by adjusting handover-related cell parameters.

[0284] However, such cell-level network optimization mechanisms have limitations in that they cannot solve problems specific to individual subscribers. Some subscribers may repeatedly experience service interruptions even when overall cell performance appears satisfactory. While these issues can significantly impact the quality of service perceived by actual users, they cannot be detected by cell-level optimization. This is because problems are detected based on average cell key performance indicators (KPIs), but KPIs are insufficient to capture problems that individual subscribers repeatedly experience. Therefore, to address these issues, the present disclosure proposes subscriber-level network optimization, a conceptual example of which is shown in FIG. 16.

[0285] One of the characteristics of subscriber-specific issues is that they are influenced by contextual factors, such as user behavior patterns. In particular, these problems can occur repeatedly along specific routes that users frequently take. In addition to mobility, these issues are also affected by factors related to the devices used by the users. Since features such as wireless measurement can vary by device, the same route may repeatedly cause problems only for subscribers using specific device types.

[0286] AI / ML is one of the core components of 5G and 6G and higher networks. Because AI learns by extracting patterns from data, it can make more accurate decisions even in complex situations that are difficult to resolve with rule-based approaches. Furthermore, it provides data-driven automation solutions that enable efficient operations and support continuous improvement over time.

[0287] Therefore, by utilizing AI for subscriber-level optimization, it is possible to extract subscriber-specific features that are impossible with cell-level optimization. Furthermore, this can serve as an efficient solution as it eliminates the need to establish clear rules for each subscriber. Currently, LTE / NR networks collect extensive data through trace servers for network maintenance and management. In 6G networks, this data can be leveraged to provide various customized services, and subscriber-level optimization is one of the key application areas.

[0288] This disclosure proposes a novel end-to-end framework for solving subscriber-specific problems in which a Radio Access Network (RAN) and a Core Network (CN) operate cooperatively. The CN can collect historical data at the subscriber level and use AI / ML to extract subscriber-specific patterns. The RAN can predict and resolve recurring problems based on real-time measurement data and patterns extracted by the CN. The key contributions of this disclosure are as follows:

[0289] An AI-based subscriber-level mobility optimization framework is proposed. This can provide a solution to subscriber-specific problems that could not be sufficiently resolved by cell-level optimization methods. A clustering-based pattern extraction model is also proposed as a data-driven approach. A detailed operational flow including CN and RAN operations can be presented.

[0290] • Performance evaluation results can be presented based on commercial network data. The proposed solution can be verified using data collected from commercial networks. The evaluation focuses on identifying connection failures repeatedly experienced by specific subscribers. As a result, it can be confirmed that subscriber-specific problems can be effectively resolved. The results indicate that performance varies depending on each user's behavioral patterns, namely how often they visit problem paths and experience recurring problems.

[0291] The remainder of this initiation can be structured as follows. Chapter 2 proposes a subscriber-level mobility optimization framework and an overall operational flow. Chapter 3 presents the results of the performance evaluation.

[0292] 2. Subscriber-Level Mobility Optimization Framework

[0293] Figure 17 illustrates the overall operational flow of subscriber-level mobility optimization. The operational flow consists of operations performed in the CN and RAN.

[0294] In CN, various historical data can be collected for each subscriber. Based on recorded data representing connection failure scenarios, target subscribers can be selected to apply subscriber-level optimization. Subsequently, data patterns can be extracted from problem cases using AI / ML. The extracted patterns are transmitted to the base station (BS) to which the target subscriber is connected.

[0295] In the RAN, when a subscriber connects, the BS predicts recurring problems based on real-time measurement results and patterns transmitted from the CN. If the prediction results determine that the subscriber is highly likely to experience a problem, mobility-related configurations can be applied to the target user to avoid the problem.

[0296] 2.1. Data Collection

[0297] First, the CN can collect historical data for each subscriber. The 3GPP specification defines Minimizing Operational Tests (MDT) procedures to facilitate this data collection. Through these procedures, the CN can collect user-related data periodically or upon the occurrence of specific events. The collected data may be stored in a Trace Collection Entity (TCE). The following describes the data collection messages and the types of information collected:

[0298] ㆍ Immediate MDT (M1): Provides downlink (DL) signal measurement results for the service cell and neighboring cells measured by the user equipment (UE). The BS can collect this information periodically or on an event basis and transmit it to the TCE.

[0299] ㆍ RLF Report: Provides information about RLF and HO failures experienced by the UE. When a failure occurs, the cell where the failure occurred, the time of the failure, and the cell where the RRC connection is re-established are transmitted by the UE to the base station via an RRC signal. The BS can transmit this information to the TCE.

[0300] • Location Report: Provides location information of the UE. The user can obtain cell trajectory information, which includes the order of connected cells prior to failure and the order of time spent in each cell. This procedure can be performed via S1AP between the BS and the Mobility Management Entity (MME), or via NGAP between the BS and the Access and Mobility Management Function (AMF).

[0301] Data collected by TCE can be utilized in a data analysis server that includes network data analysis functions (NWDAF) or operations, management, and maintenance (OAM) functions.

[0302] 2.2. Select Target Subscribers

[0303] Next, the CN selects target subscribers to whom subscriber-level optimization will be applied based on collected historical data. Specifically, problematic subscriber-cell pairs are selected, where the subscriber represents the target for optimization and the cell represents the location where optimization should be performed. To identify problems that cannot be resolved by cell-level optimization, the CN may select subscribers who experience below-average network quality and have encountered recurring problems in specific paths or locations. For example, the following criteria may be considered when selecting target subscribers.

[0304] ㆍ Handover performance metrics

[0305] [Mathematical Formula 1]

[0306]

[0307] Here represents the HO attempt rate of u of a subscriber within cell k, and represents the average HO attempt rate of cell k. represents the threshold of the HO attempt rate, which indicates the maximum performance margin between individual subscribers and the cell average.

[0308] [Mathematical Formula 2]

[0309]

[0310] Here represents the HO failure rate of subscriber u within cell k, and represents the average HO failure rate of cell k. represents the threshold for HO failure, which indicates the maximum performance margin between the individual subscriber and the cell average.

[0311] ㆍ RLF performance metrics

[0312] [Mathematical Formula 3]

[0313]

[0314] Here represents the RLF rate of subscriber u within cell k, and represents the average RLF rate of cell k. represents the threshold of the RLF rate, which indicates the maximum performance margin between individual subscribers and the cell average.

[0315] [Mathematical Formula 4]

[0316]

[0317] Here represents the average duration until the RRC connection is re-established after subscriber u experiences RLF in cell k, and represents the average duration until the RRC connection is re-established after RLF for cell k. represents the threshold for RRC re-establishment time, which represents the maximum performance margin between individual subscribers and the cell average.

[0318] In addition, target subscribers can be identified by applying a series of statistical analyses that consider user behavior patterns in multiple stages.

[0319] 2.3. AI-based Problematic Pattern Extraction

[0320] The data experienced by selected target subscribers prior to the occurrence of recurring problems exhibits common spatial and trajectory-related characteristics. Accordingly, common patterns associated with these problems are extracted using AI / ML-based approaches. For this purpose, two types of historical data can be used.

[0321] ㆍ Cell Trajectory: The sequence of cells connected by the user before failure.

[0322] As a cell identifier, a Cell Global Identifier (CGI) or a combination of the Absolute Radio Frequency Channel Number (ARFCN) and the Physical Cell Identifier (PCI) can be used.

[0323] ㆍ DL signal quantity measurement: This is the result of a sequence of radio measurements for the service cell and neighboring cells prior to the failure. Reference signal received power (RSRP), reference signal received quality (RSRQ), and signal-to-interference plus noise ratio (SINR) can be used as measurement metrics.

[0324] Clustering can be utilized to extract patterns based on similarities between time-series data observed prior to the occurrence of these problems. In a specific problem cell, multiple distinct patterns may coexist when target subscribers repeatedly experience the issue. Clustering algorithms can identify these multiple patterns by separating samples into distinct groups. The following procedures may be considered in the clustering process.

[0325] 1) Preprocessing: Time series data collected by MDT may exhibit non-uniform temporal structures. To enable further analysis, the time series must be preprocessed into uniformly sampled time series. If multiple samples exist within a predetermined time interval, they are aggregated into a single representative value. Aggregation methods may vary depending on the data type. For numerical variables, the mean is widely used. For categorical variables, a mode can be used. Alternatively, categorical variables can be aggregated into a set value by removing duplicates. In the case of cell trajectory data, set-based aggregation can minimize information loss by preserving information on all visited cells.

[0326] Even after uniform resampling, missing values ​​may still exist within sparse data. Imputation strategies vary depending on the data type.

[0327] 2) Similarity evaluation: The similarity between two time series can be evaluated using the Dynamic Time Warp (DTW) algorithm.

[0328] 3) Clustering method: A two-stage time-series clustering system can be proposed as a clustering strategy.

[0329] 4) Extraction of reference patterns: When clusters are formed by a clustering method, reference patterns for each cluster can be derived.

[0330] 2.4. Problem Prediction

[0331] Problem prediction aims to detect whether there is a possibility of recurring problems occurring to the target subscriber based on extracted patterns. To this end, extracted patterns are transmitted from the CN to the RAN. Specifically, when the target subscriber enters a specific cell, the extracted pattern information is transmitted from the MME to the BS via S1AP or from the AMF to the BS via NGAP. Problem prediction can be performed through a two-stage similarity check between the extracted patterns and real-time measurement data.

[0332] In the first step, BS can perform a primary similarity check by comparing the reference cell trajectory pattern with the user's current cell trajectory. Similarity is quantified as the distance between the two sequences. If the distance score is below a predefined threshold, BS determines whether the UE followed the expected cell trajectory pattern and initiates a secondary similarity check.

[0333] The secondary similarity check calculates the distance between the reference DL measurement pattern and the current DL measurement history. This comparison can be performed using a sliding window method. Once the secondary similarity check is initiated, it can be performed at each time interval until the UE leaves the target cell.

[0334] Therefore, if the current cell trajectory and DL measurement results are similar to the results extracted from the problem path, it can be inferred that the target subscriber is heading toward the problem path.

[0335] 2.5. Subscriber-Only Mobility Configuration

[0336] If the RAN predicts that there is a possibility of a recurring problem occurring for a target subscriber, it can avoid this by selectively reconfiguring the subscriber's mobility-related parameters. One common avoidance strategy is to transfer the target subscriber to a cell with an alternate band. To this end, a user-customized measurement configuration can be delivered via an RRC reconfiguration message. An example of a subscriber-specific mobility configuration is shown in Fig. 21. However, parameter configuration strategies to avoid the problem may vary depending on the type of problem. For example, if the problem is caused by a ping-pong HO, the offset of individual cells in the measurement configuration can be increased, or the cell causing the ping-pong can be excluded from the subscriber's HO candidate set.

[0337] 3. Performance Evaluation

[0338] This section presents details of a performance evaluation performed based on commercial network data for subscriber-level optimization. The evaluation is based on the following two types of data:

[0339] ㆍ Driving test data

[0340] Commercial subscriber data

[0341] An evaluation was conducted to verify how effectively the proposed system can detect RLF and HO failure problems that specific subscribers repeatedly experience. Accordingly, the prediction accuracy was evaluated based on extracted reference patterns and similarity check procedures.

[0342] [Table 1]

[0343]

[0344] Since the similarity check uses a sliding window method, prediction accuracy is also evaluated at the group level. A session is defined as the total duration from the start to the end of the sliding window, and accuracy is evaluated for each session. Specifically, prediction accuracy is first evaluated at each individual time step, and the results are aggregated at the session level. This approach helps minimize redundant evaluations for a single true RLF event. Definitions of grouped metrics, such as Group True Positive (TP), Group False Negative (FN), Group False Positive (FP), and Group True False (TN), are provided in Table 1. The prediction window is defined as the time interval between the moment a prediction is made and the maximum expected time of a potential failure event.

[0345] Recall and precision can be derived based on the above metrics. Recall and precision exhibit a trade-off relationship, and overall performance is considered higher the closer the result is to the upper right corner of the precision-recall curve.

[0346] Recall: This performance metric is defined as TP_Grouped / (TP_Grouped+FN_Grouped). It represents the rate at which connection failure events are detected in the problem path. Low recall can lead to missed failure detections and result in connection failures.

[0347] Precision: This performance metric is defined as TP_Grouped / (TP_Grouped+FP_Grouped). It indicates the accuracy of detection. Low precision can lead to unnecessary HOs, resulting in resource usage and signal overhead.

[0348] In addition, prediction performance is influenced by the following variables.

[0349] ㆍ Decision Threshold: Used to determine whether a connection has failed based on a similarity check. As the threshold increases, cases with relatively low similarity may also be classified as failures. As a result, recall tends to increase, but accuracy tends to decrease.

[0350] ㆍ Sequence Length: This parameter is the length of the input time series used for prediction. The appropriate sequence length may vary depending on the problem context. Cell trajectory data may require a longer input length than DL measurement data.

[0351] ㆍ Prediction Length: This parameter is the valid time window in which failure is expected to occur. This interval can be adjusted to account for variations in user speed. Increasing the prediction length can improve the robustness of the model.

[0352] 3.1. Evaluation Results: Driving Test Data

[0353] Driving test data was collected through repeated measurements. Using this dataset, it was investigated whether problems repeatedly experienced in specific cells could be characterized by specific RSRP measurement sequence patterns. Additionally, the validity of predicting these problems based on the extracted patterns was verified. Since the user's movement paths were predefined, cell path patterns were not considered; instead, similarity checks were performed using only RSRP measurement patterns.

[0354] Performance evaluation was performed on the top 3 and top 6 cells with the highest number of RLF or HO failures. For each test, performance was evaluated by varying key parameters such as decision threshold, sequence length, and prediction length. The results were derived based on the precision-recall curve shown in Figure 19.

[0355] A performance evaluation was conducted on how well connection failures, namely RLF and HO failures, can be predicted based on RSRP measurement patterns for problem paths. As a result, it was confirmed that when parameters such as the sequence length of the data and the similarity check threshold are optimally set, 91% of connection failures occurring in the path are detected with 88% accuracy.

[0356] 3.2. Evaluation Results: Commercial Subscriber Data

[0357] When conducting performance evaluations using commercial subscriber data, the following additional factors may be considered when compared to evaluations based on drive test data.

[0358] ㆍ Target subscriber selection: Since data is collected from thousands of subscribers via unrestricted paths, target subscribers can be selected based on the performance indicators described in Section 2.2. Additionally, before extracting RSRP measurement patterns, actual problem paths can be classified based on cell trajectories.

[0359] • Non-uniform and sparse data: RSRP measurement results are collected using the commercial network MDT procedure described in Section 2.1. However, the measurement period rate set in the MDT may be longer than the measurement period rate typically set at base stations. This is due to capacity limitations of the analysis server, as it must manage results collected from the entire network. To overcome this, the data is pre-processed before clustering is performed.

[0360] A performance evaluation was conducted to assess how well connection failures are predicted based on the cell trajectory and RSRP measurement patterns of the problem path. As shown in Table 2, it was confirmed that up to 89% of connection failures among RLF and HO failures in the problem path were detected with 94% accuracy. Detection performance may vary depending on the subscriber's behavioral patterns, namely how often they visit the problem path and experience problems.

[0361] [Table 2]

[0362]

[0363] 4. Conclusion

[0364] This disclosure proposes a solution for subscriber-specific problems that cannot be resolved by existing cell-level optimization methods. A subscriber-level mobility optimization framework and a complete operational flow are introduced. Furthermore, a method for extracting problematic path patterns using AI-based clustering applied to data is proposed. Based on the extracted patterns, it is demonstrated that subscriber-specific problems can be predicted and resolved in advance by detecting whether a subscriber is moving along a problematic path. Performance evaluation was performed using commercial network data. The results confirm that the proposed solution can significantly reduce connectivity failures caused by subscriber-specific problems.

Claims

1. A method performed by a first base station in a wireless communication system, A step of receiving a first message comprising first information for identifying a terminal, second information regarding a cell trajectory, third information regarding a cell-related signal pattern, and fourth information indicating a failure type; A step of identifying that the terminal moves along the cell trajectory based on the first information and the second information; A step of identifying that the signal pattern received from the terminal and the signal pattern of the third information are similar; and Based on the fourth information above, the method comprises the step of transmitting a second message to the terminal, the second message including setting information for preventing failure of the terminal. method.

2. In Claim 1, The above first message is received from the NWDAF (network data analytics function) entity via the AMF (access and mobility management function) entity, and The first message above includes any one of an INITIAL CONTEXT SETUP message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message. method.

3. In Claim 1, The above first message is received from the second base station based on the Xn interface, and The first message above includes either a HANDOVER REQUEST message or a RETRIEVE UE CONTEXT RESPONSE message, method.

4. In Claim 1, The above types of failure are, A first type indicating frequent cell changes, a second type indicating repeated handovers between two cells, or a third type indicating connection failure, comprising at least one of these. method.

5. In Claim 4, If the above failure type is the first type, the above setting information includes setting information for moving the terminal to a specific cell, method.

6. In Claim 4, If the above failure type is a second type, the above setting information includes fifth information for adjusting the evaluation of signal quality regarding the cell, and The above fifth information includes cell individual offset (CIO), method.

7. In Claim 4, If the above failure type is a third type, the above setting information includes information for excluding the cell where the connection failure occurs from the candidate cells selectable by the terminal. method.

8. In Claim 1, The signal pattern received from the terminal includes a signal pattern measured for the serving cell of the terminal and a signal pattern measured for the neighboring cell of the terminal, and The signal pattern received from the terminal includes a pattern for at least one of RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), or SINR (signal to interference plus noise ratio). method.

9. In the first base station of a wireless communication system, At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the first base station: Receiving a first message comprising first information for identifying a terminal, second information regarding a cell trajectory, third information regarding a cell-related signal pattern, and fourth information indicating a failure type, and Based on the first information and the second information, identifying that the terminal moves along the cell trajectory, and Identifying that the signal pattern received from the terminal and the signal pattern of the third information are similar, and Based on the above fourth information, configured to transmit a second message to the terminal that includes setting information for preventing failure of the terminal, 1st base station.

10. In Claim 9, The above first message is received from the NWDAF (network data analytics function) entity via the AMF (access and mobility management function) entity, and The first message above includes any one of an INITIAL CONTEXT SETUP message, a UE CONTEXT MODIFICATION REQUEST message, or a PATH SWITCH REQUEST ACKNOWLEDGE message. 1st base station.

11. In Claim 9, The above first message is received from the second base station based on the Xn interface, and The first message above includes either a HANDOVER REQUEST message or a RETRIEVE UE CONTEXT RESPONSE message, 1st base station.

12. In Claim 9, The above types of failure are, A first type indicating frequent cell changes, a second type indicating repeated handovers between two cells, or a third type indicating connection failure, comprising 1st base station.

13. In Claim 12, If the above failure type is the first type, the above setting information includes setting information for moving the terminal to a specific cell, and If the above failure type is a second type, the above setting information includes fifth information for adjusting the evaluation of signal quality regarding the cell, and If the above failure type is a third type, the above setting information includes information for excluding the cell where the connection failure occurs from the candidate cells selectable by the terminal, and The above fifth information includes cell individual offset (CIO), 1st base station.

14. In Claim 9, The signal pattern received from the terminal includes a signal pattern measured for the serving cell of the terminal and a signal pattern measured for the neighboring cell of the terminal, and The signal pattern received from the terminal includes a pattern for at least one of RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), or SINR (signal to interference plus noise ratio). 1st base station.

15. A method performed in the NWDAF (network data analytics function) entity of a wireless communication system, A step of receiving first information regarding the cell trajectory of the terminal, second information regarding the cell-related signal pattern measured at the terminal, and third information regarding the failure of the terminal; Based on the first information, the second information, and the third information, a step of generating fourth information representing a representative cell trajectory for the failure, fifth information representing a representative signal pattern for the failure, and sixth information indicating a type of failure; and A step comprising transmitting the above-mentioned fourth information, fifth information, and sixth information, method.

Images