Method and apparatus for handover using artificial intelligence in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate beyond a 4G communication system such as LTE. This method performed by a terminal in a wireless communication system comprises the steps of: transmitting, to a base station for a serving cell, a first message including capability information of the terminal associated with an artificial intelligence model; receiving, from the base station, a second message including an indication of a first handover for a first target cell, and configuration information related to the artificial intelligence model; predicting the first handover by using the artificial intelligence model on the basis of the configuration information; and if the prediction is a success, performing a procedure of the first handover for the first target cell.

Description

Method and device for handover using artificial intelligence in a wireless communication system

[0001] The present disclosure relates to a method and device for handover using artificial intelligence in a wireless communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of wireless interface architecture / protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It could serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing this technology.

[0008] Various embodiments of the present disclosure may have as a first object a device and method for performing handover using an artificial intelligence model (e.g., a machine learning or deep learning model, etc.) in a wireless communication system.

[0009] The problems that the various embodiments of the present disclosure seek to solve are not limited by the contents mentioned in the present disclosure.

[0010] According to one embodiment of the present disclosure, a method performed by a terminal of a wireless communication system comprises the steps of: transmitting a first message including capability information of a terminal associated with an artificial intelligence model to a base station for a serving cell; receiving a second message including an instruction for a first handover to a first target cell and configuration information regarding an artificial intelligence model from the base station; performing a prediction for the first handover using the artificial intelligence model based on the configuration information; and performing a procedure for the first handover to the first target cell when the prediction is successful.

[0011] Various embodiments of the present disclosure can provide a device and method capable of effectively providing a service in a wireless communication system.

[0012] The effects that can be obtained from the present disclosure are not limited to the effects mentioned in the various embodiments, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0013] FIG. 1 is a diagram illustrating the structure of a wireless communication system according to one embodiment of the present disclosure.

[0014] FIG. 2 is a diagram for explaining a wireless connection state transition of a terminal in a wireless communication system according to one embodiment of the present disclosure.

[0015] FIG. 3 is a flowchart illustrating a process in which a terminal performs cell measurement and reporting operations according to one embodiment of the present disclosure.

[0016] FIG. 4 is a diagram for explaining an operation of a terminal reporting cell measurement results when a specific condition is satisfied according to one embodiment of the present disclosure.

[0017] FIG. 5 is a diagram illustrating an example of input information (Input) and output information (Output) of an artificial intelligence model used by a terminal according to one embodiment of the present disclosure.

[0018] FIG. 6 is a diagram illustrating a procedure for handover between a terminal and a base station according to one embodiment of the present disclosure.

[0019] FIG. 7 is a diagram illustrating a procedure for handover based on prediction and related reporting using an artificial intelligence model between a terminal and a base station according to one embodiment of the present disclosure.

[0020] FIG. 8 is a diagram illustrating a procedure for handover based on prediction and related reporting using an artificial intelligence model between a terminal and a base station according to one embodiment of the present disclosure.

[0021] FIG. 9 is a diagram illustrating a procedure for handover based on prediction and related reporting using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0022] FIG. 10 is a diagram illustrating a procedure for prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0023] FIG. 11 is a diagram illustrating a procedure for prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0024] FIG. 12 is a diagram illustrating a procedure for prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0025] FIG. 13 is a diagram illustrating a procedure for prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0026] FIG. 14 is a diagram illustrating a procedure for prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0027] FIG. 15 is a diagram illustrating the structure of a terminal according to one embodiment of the present disclosure.

[0028] FIG. 16 is a diagram illustrating the structure of a base station according to one embodiment of the present disclosure.

[0029] In describing the embodiments of this disclosure, descriptions of technical details that are well-known in the technical field to which this disclosure pertains and are not directly related to this disclosure will be omitted. This is to avoid obscuring the gist of this disclosure by omitting unnecessary explanations and to convey it more clearly. Furthermore, the terms described below are defined based on their functions in this disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents throughout this specification.

[0030] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0031] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Like reference numerals designate like elements throughout the disclosure.

[0032] At this time, it will be understood that each block of the processing flow diagrams and combinations of the flow diagrams can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flow diagram block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flow diagram block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0033] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0034] Here, the term '~ unit' used in the present embodiment means a software or hardware component such as an FPGA or ASIC, and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Accordingly, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0035] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided for convenience of explanation. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0036] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although the LTE or LTE-A system may be described below as an example, the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, the 5th generation mobile communication technology (5G, new radio, NR) or the 5G advanced system developed after LTE-A may be included in a system to which the embodiments of the present disclosure may be applied, and 5G below may also be a concept that includes existing LTE, LTE-A, and other similar services.

[0037] For convenience of explanation, this disclosure uses terms and names defined in the 5GS and NR standards defined by the 3rd Generation Partnership Project (3GPP). However, the present invention is not limited to these terms and names and can be equally applied to wireless communication networks conforming to other standards. For example, the present invention can be applied to the 3GPP 5GS / NR (5th generation mobile communication standard) or the 3GPP 5G advanced standard.

[0038] FIG. 1 is a diagram illustrating the structure of a wireless communication system according to one embodiment of the present disclosure.

[0039] Referring to FIG. 1, a wireless access network of a mobile communication system (New Radio, NR) according to an embodiment of the present disclosure may be composed of a base station (next generation Node B, hereinafter referred to as gNB) (110) and an AMF (105, access and mobility management function or New Radio Core Network). A user terminal (New Radio User Equipment, hereinafter referred to as (NR) UE or terminal) (115) may access an external network through the gNB (110) and the AMF (105). The mobile communication system according to an embodiment of the present disclosure may be a next generation wireless mobile communication system, and the base station may be a next generation wireless base station.

[0040] In FIG. 1, the gNB (110) may correspond to the eNB (130) (Evolved Node B) of the existing LTE system. The gNB is connected to the NR UE (115) through a wireless channel (120) and may provide a service that is superior to the existing Node B. In the next-generation wireless mobile communication system according to an embodiment of the present disclosure, since all user traffic is serviced through a shared channel, a device that collects status information such as buffer status, available transmission power status, and channel status of UEs and performs scheduling is required, and the gNB (110) may be in charge of this. One gNB can typically control multiple cells. In order to implement ultra-high-speed data transmission compared to the existing LTE, it may have a bandwidth higher than the existing maximum bandwidth, and beamforming technology may be additionally grafted using the orthogonal frequency division multiplexing (OFDM) scheme as a wireless access technology. Additionally, an adaptive modulation and coding (AMC) method that determines the modulation scheme and channel coding rate according to the channel status of the terminal can be applied.

[0041] AMF (105) can perform functions such as mobility support, bearer setup, and QoS (quality of service) setup. AMF (105) is a device that is responsible for various control functions as well as mobility management functions for terminals and can be connected to multiple base stations.

[0042] In addition, the mobile communication system according to one embodiment of the present disclosure can be interoperable with an existing LTE system, and the AMF (105) can be connected to an MME (mobility management entity) (125) through a network interface. The MME (125) can be connected to an eNB (130), which is an existing base station. An NR UE (115) supporting LTE-NR Dual Connectivity can transmit and receive data while maintaining a connection (135) with not only the gNB (110) but also the eNB (130).

[0043] FIG. 2 is a diagram for explaining a wireless connection state transition of a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0044] In a wireless communication system according to an embodiment of the present disclosure, a terminal may have three radio connection states (RRC (radio resource control) states) or RRC modes. The connected mode (RRC_CONNECTED, 205) is a radio connection state in which the terminal can transmit and receive data. The idle mode (RRC_IDLE, 230) is a radio connection state in which the terminal monitors whether paging is transmitted to itself. The two modes (connected mode and idle mode) are radio connection states that can also be applied to an LTE system, and the detailed technology is the same as that of the LTE system. The wireless communication system according to an embodiment of the present disclosure may be a next-generation mobile communication system.

[0045] In a wireless communication system according to an embodiment of the present disclosure, an inactive (RRC_INACTIVE) radio connection state (215) may be defined. In the inactive radio connection state, the UE context is maintained between the base station and the terminal, and RAN (radio access network)-based paging may be supported. The characteristics of the inactive radio connection state are listed below.

[0046] - Cell re-selection mobility;

[0047] - CN - NR RAN connection (both C / U-planes (control plane / user plane)) has been established for UE;

[0048] - The UE AS (Access Stratum) context is stored in at least one gNB and the UE;

[0049] - Paging is initiated by NR RAN;

[0050] - RAN-based notification area is managed by NR RAN;

[0051] - NR RAN knows the RAN-based notification area which the UE belongs to;

[0052] According to one embodiment of the present disclosure, a terminal in an inactive wireless connection state can transition to a connected mode or a standby mode using a specific procedure. The transition (210) between the connected mode and the inactive mode can be performed through Resume or Release with suspend. For example, the terminal can transition from INACTIVE mode to connected mode through the Resume procedure, and can transition from connected mode to INACTIVE mode by receiving a Release message including suspend configuration information (210). The above procedure is performed by transmitting and receiving one or more RRC messages between the terminal and the base station, and can consist of one or more operations. In addition, the terminal can transition from INACTIVE mode to standby mode through the Release procedure after Resume (220). The transition (225) between the connected mode and the standby mode can follow the existing LTE technology. For example, the transition between modes can be performed through the establishment or release procedure.

[0053] FIG. 3 is a flowchart illustrating a process in which a terminal performs cell measurement and reporting operations according to an embodiment of the present disclosure.

[0054] According to one embodiment of the present disclosure, in operation 315, the terminal (305) may report its capability information to the base station (310). In operation 320, the base station (310) may transmit an RRCReconfiguration message including configuration information (measConfig IE) related to cell measurement operation to the terminal (305).

[0055] The configuration information (measConfig IE) may include information necessary for reporting the results measured by the terminal (305) to the base station (310) depending on the type of measurement report (e.g., periodical, event-triggered, event-triggered periodical). For example, in the case of “event-triggered” or “event-triggered periodical,” the terminal (305) may report a predetermined measurement result when a specific event set based on the configuration information (measConfig IE) is satisfied. For example, the following events may be set in the NR system.

[0056] - Event(s) related to intra- / inter-RAT measurements are as shown in Table 1 below.

[0057] Event A1: Serving becomes better than absolute threshold;Event A2: Serving becomes worse than absolute threshold;Event A3: Neighbour becomes amount of offset better than PCell / PSCell;Event A4: Neighbour becomes better than absolute threshold;Event A5: PCell / PSCell becomes worse than absolute threshold1 AND Neighbour / SCell becomes better than another absolute threshold2;Event A6: Neighbour becomes amount of offset better than SCell;Event D1: Distance between UE and a reference location referenceLocation1 becomes larger than configured threshold distanceThreshFromReference1 and distance between UE and a reference location referenceLocation2 becomes shorter than configured threshold distanceThreshFromReference2;Event B1: Neighbour becomes better than absolute threshold;Event B2: PCell becomes worse than absolute threshold1 AND Neighbour becomes better than another absolute threshold2;

[0058] - Similar to condition-based measurement reporting, in condition-based handover, when a specific event is satisfied, the terminal (305) can perform a handover according to condition-based handover configuration information. Event(s) related to condition-based handover are as shown in Table 2 below.

[0059] CondEvent A3: Conditional reconfiguration candidate becomes amount of offset better than PCell / PSCell;CondEvent A4: Conditional reconfiguration candidate becomes better than absolute threshold;CondEvent A5: PCell / PSCell becomes worse than absolute threshold1 AND Conditional reconfiguration candidate becomes better than another absolute threshold2;CondEvent D1: Distance between UE and a reference location referenceLocation1 becomes larger than configured threshold distanceThreshFromReference1 and distance between UE and a reference location referenceLocation2 of conditional reconfiguration candidate becomes shorter than configured threshold distanceThreshFromReference2;CondEvent T1: Time measured at UE becomes more than configured threshold t1-Threshold but is less than t1-Threshold + duration;

[0060] - (Sidelink) When a specific event is satisfied in the Relay, the terminal (305) can perform a specific action. Event(s) related to the Relay are as shown in Table 3 below.

[0061] Event X1: Serving L2 U2N Relay UE becomes worse than absolute threshold1 AND NR Cell becomes better than another absolute threshold2;Event

[0062] - In the case of NR-U (Unlicensed), when a specific event is satisfied, the terminal (305) can perform a specific action. Event(s) related to NR-U are as shown in Table 4 below.

[0063] Event I1: Interference becomes higher than absolute threshold.

[0064] In operation 325, the terminal (305) can evaluate whether the set events are satisfied. If the events described above are continuously satisfied with a predetermined condition for a predetermined time interval (time-to-trigger), the terminal (305) can consider the event to be satisfied.

[0065] In operation 330, the terminal (305) may report a MeasurementReport message containing the measurement result to the base station (310) when the set condition is satisfied. Alternatively, the terminal (305) may perform a predetermined operation corresponding to the condition, for example, a condition-based handover.

[0066] The base station (310) that receives the measurement result from the terminal (305) can use the measurement result for a predetermined purpose. For example, in operation 335, the base station (310) can determine whether to trigger a handover (HO) of the terminal (305). In operation 340, if the base station (310) triggers a handover, it can request a handover to the target cell(s). In operation 345, the base station (310) can transmit handover configuration information configured based on predetermined configuration information received from the target cell(s) to the terminal (305). In operation 350, the terminal (305) that received the handover configuration information can perform a handover.

[0067] FIG. 4 is a diagram for explaining an operation of a terminal reporting cell measurement results when a specific condition is satisfied according to an embodiment of the present disclosure.

[0068] Referring to FIG. 4, the terminal (410) can evaluate the signal strength or quality of the base station (405) signal based on the SSB (synchronization signal block or SS / PBCH block) or CSI-RS (channel state information reference singal) transmitted from the base station (405). Hereinafter, for convenience of explanation, the cell measurement result reporting operation of the terminal (410) is described mainly with respect to SSB, but the same can be applied to CSI-RS.

[0069] In the case of SSB, the transmission cycle of SSB can be determined according to the settings of the base station (405). Generally, the transmission cycle of SSB can be set to 20 ms, and the base station (405) can transmit SSB with a cycle of up to 160 ms.

[0070] When the base station (405) sets Event A2 to the terminal (410), the terminal (410) can continuously evaluate whether the RSRP value measured based on SSB is lower than the threshold during a predetermined time period (time-to-trigger, TTT) from the time point (415) when the RSRP (reference signal received power) value measured based on SSB by the terminal (410) becomes lower than the set absolute threshold value.

[0071] If the RSRP value measured based on SSB is continuously lower than the threshold from the initial point (415) when the RSRP value becomes lower than the set absolute threshold value to the point (420) when a predetermined time-to-trigger (TTT) has elapsed, the terminal (410) may consider that the Event A2 has been satisfied and may report a measurement report triggered by the Event A2 to the base station (405). As described above, by considering the TTT in determining whether the conditions for performing the measurement report are satisfied, the variability of the measurement signal may be corrected. The TTT value may be set by the base station (405) for each Event.

[0072] If the Events continuously satisfy a predetermined condition for a predetermined time interval (TTT), the terminal (410) can perform an action corresponding to the purpose of the Event according to the purpose of the configured Event. If the type of measurement report according to the measurement-related setting information received by the terminal (410) is set to “periodical” or “event-triggered periodical,” the terminal (410) can perform a measurement report periodically.

[0073] In the existing L3 (Layer 3) handover mechanism, handover can be triggered and executed by the network or base station based on historical cell measurement results and / or cell measurement event(s) reported in the past. That is, it can be understood as a kind of reactive manner.

[0074] Reactive handover schemes can be effective for existing services, such as when terminals move between macro cells or when they have low mobility. However, reactive handover schemes can be problematic when terminals have high mobility, move between dense micro cells, or for future services such as XR. For example, unintended consequences such as handover failures, radio link failures, ping-pong behavior, throughput loss, or premature / late handovers can occur.

[0075] Accordingly, conditional handover was introduced in Rel-16 to improve handover robustness, and lower-layer triggered mobility (LTM) handover was introduced in Rel-18 to reduce service interruption due to frequent handovers between small cells. However, these two handover mechanisms (conditional handover and LTM) may not be sufficient because they are still based on a reactive approach.

[0076] On the other hand, handover mechanisms based on artificial intelligence (AI / ML) algorithms can enable proactive approaches. For example, a UE can generate predicted cell measurement information for the future using an AI / ML model and report this predicted cell measurement information to the base station (or network). This allows the base station to prepare for handovers in advance, preventing delays. Furthermore, by proactively instructing the UE to perform a handover, the UE can be handed over to another base station or cell before a problem (e.g., radio link failure (RLF)) occurs. Furthermore, by receiving predicted cell measurement information for the UE, the base station can achieve improved handover and / or radio resource management (RRM) performance compared to reactive approaches. For example, the base station can make better network operation / configuration decisions or take proactive measures to avoid unintended events. Alternatively, the base station or network may generate predictive information by running an artificial intelligence model (machine learning or deep learning) using the report information received from the terminal, and the base station or network may instruct the terminal to perform a preemptive handover using the generated predictive information.

[0077] FIG. 5 is a diagram illustrating an example of input information (Input) and output information (Output) of an artificial intelligence model used by a terminal according to one embodiment of the present disclosure.

[0078] In step 505, the terminal may use L3 (Layer 3) and / or L1 (Layer 1) measurement information (e.g., measured cell information, measured time information, measured RSRP value, measured RSRQ value, measured SINR value) for the serving cell and / or neighboring cells (from the past to the present or present) as input information of the artificial intelligence model.

[0079] In step 510, the terminal may use a reference time or a predicted time (T) as input information for the AI ​​model. The reference time may indicate a specific time in the future. In one embodiment of the present disclosure, the terminal may use a reference time period or a predicted time period (T) as input information for the AI ​​model. The reference time period may indicate a specific time period in the future.

[0080] In one embodiment of the present disclosure, when predicting / deriving a cell measurement value as an output, the artificial intelligence model of the terminal can derive a cell measurement value predicted at a time point (or time interval) (T) indicated by an input reference time point (or time interval).

[0081] In one embodiment of the present disclosure, when predicting / deriving the Handover Failure (HOF) probability as an output, the AI ​​model of the terminal can derive the predicted HOF probability at a time point (T) indicated by the input reference time point. For example, the derived HOF probability here may mean at least one of the following:

[0082] For example, the HOF probability may represent the probability that the UE will not complete the handover to the target cell (e.g., not complete the transmission of the RRCReconfigurationComplete message) (e.g., within a fixed or configured time interval) when it is assumed that the UE receives a handover command (e.g., an RRCReconfiguration message including reconfigurationWithSync) at a reference time (or time interval) T.

[0083] The HOF probability according to embodiments of the present disclosure may indicate any one of 1) a probability of detecting or declaring an RLF (e.g., within a fixed or set time interval) before and / or after the terminal receives a handover command at a reference time point (or time interval) T, 2) a probability of timer T304 expiring, 3) a probability of timer T311 expiring, 4) a probability of timer T310 expiring, 5) a probability of timer T312 expiring, and / or 6) a probability of receiving (X consecutive) out-of-sync indicators from L1 (Layer 1) (e.g., from L3).

[0084] The HOF probability according to embodiments of the present disclosure may indicate any one of: 1) a probability of detecting or declaring an RLF (e.g., within a fixed or set time interval), 2) a probability of timer T304 expiring, 3) a probability of timer T311 expiring, 4) a probability of timer T310 expiring, 5) a probability of timer T312 expiring, and / or 6) a probability of receiving (X consecutive) out-of-sync indicators from L1 (Layer 1) (e.g., from L3), after the UE performs a successful handover to the target cell (e.g., after successfully completing transmission of an RRCReconfigurationComplete message) after receiving a handover command at a reference time point (or time interval) T.

[0085] In one embodiment of the present disclosure, when predicting / deriving an RLF (Radio link failure) probability as an output, the terminal can derive the predicted RLF probability at a time point (or time interval) (T) indicated by an input reference time point (or time interval).

[0086] For example, the RLF probability here may indicate any one of: 1) the probability that the terminal detects or declares an RLF at a reference time (or time interval) T or within a fixed or set time interval relative to T, 2) the probability that timer T304 expires, 3) the probability that timer T311 expires, 4) the probability that timer T310 expires, 5) the probability that timer T312 expires, and / or 6) the probability that (X consecutive) out-of-sync indicators are received from L1 (Layer 1) (e.g., from L3).

[0087] In one embodiment of the present disclosure, when predicting / deriving a TOS (Time of Stay, time to stay in a connected cell) value as an output, the terminal can derive the predicted TOS value at a time point (or time interval) (T) indicated by the input reference time point (or time interval).

[0088] For example, the TOS value here may mean any one of the following: 1) a time until the UE detects or declares an RLF (e.g., within a fixed or configured time interval), 2) a time until timer T304 expires, 3) a time until timer T311 expires, 4) a time until timer T310 expires, 5) a time until timer T312 expires, 6) a time until it receives (X consecutive) out-of-sync indicators from L1 (Layer 1) (e.g., from L3), 7) a time until it receives a handover command to another cell, 8) a time until it completes a handover to another cell, and / or 9) a time until it transitions to an inactive or standby mode.

[0089] In one embodiment of the present disclosure, when predicting / deriving the probability of a specific event (e.g., Event A3 or Event X' or RLF or HOF) as an output, the terminal can derive the probability of occurrence of the predicted event at a time point (or time interval) (T) indicated by the input reference time point (or time interval).

[0090] In one embodiment of the present disclosure, when predicting / deriving the occurrence time or interval of a specific event (e.g., Event A3 or Event X') or RLF or HOF as an output, the terminal can derive the predicted occurrence time or interval within the time (or time interval) (T) indicated by the input reference time (or time interval).

[0091] In one embodiment of the present disclosure, when predicting / deriving network configuration parameters (e.g., RRC parameters) to be used in the future as output, the terminal can derive optimal (or appropriate or recommended) network configuration parameters (e.g., RRC parameters) predicted at a time point (or time interval) (T) indicated by an input reference time point (or time interval).

[0092] In step 515, the terminal may use at least one of the following as input information of the artificial intelligence model: RLF or handover-related timer setting information and history (from the past to the present or present) (e.g., timer length and expiration history for timers T304, T310, T311, T312), RLF or handover-related counter value (e.g., N310, N311) information and history, RLF report (e.g., RLF-Report)-related information and history (from the past to the present or present), successful HO (Handover) report (e.g., SuccessHO-Report)-related information and history, RA (Random access) report (e.g., RA-Report)-related information and history, and / or CEF (Connection establishment failure) report (e.g., ConnEstFailReport)-related information and history (from the past to the present or present).

[0093] In step 520, the terminal can use the terminal's status information (from the past to the present or present) as input information of the artificial intelligence model.

[0094] For example, the status information of the terminal may include at least one of the following: information on the remaining power (remaining battery capacity) of the terminal, whether the terminal is charged, location information of the terminal, moving speed of the terminal, moving path information of the terminal, pose and direction information of the terminal, manufacturer and / or model information of the terminal, information (e.g., performance) related to the hardware (e.g., RAM, CPU, GPU, graphic card, memory) of the terminal, parameter information set to the terminal (e.g., event setting value, TTT (Time to trigger) length setting value, timer length setting value, type of timer or TTT set to the terminal, etc.), or information related to settings that the terminal stores, maintains, and / or manages (e.g., type of timer or TTT operated by the terminal, whether the timer or TTT has started, information on how much time has passed since the timer or TTT was started, information on the remaining time until the timer expires, information on the remaining time until the TTT ends).

[0095] In step 525, the terminal can use the setting parameter information (from the past to the present or present) as input information of the AI / ML model.

[0096] For example, the configuration parameter information may include at least one of configuration information and parameter values ​​for each layer (e.g., RRC, SDAP, PDCP, RLC, MAC, PHY) set by a base station or a network, or configuration information and parameter values ​​set by AMF through NAS signaling.

[0097] In step 530, the terminal can predict / derive L3 (Layer 3) and / or L1 (Layer 1) measurement information (e.g., measured cell information, measured time information, measured RSRP value, measured RSRQ value, measured SINR value) for a serving cell and / or neighboring cells predicted at a future point in time as output information of an artificial intelligence model.

[0098] In step 535, the terminal can predict / derive the aforementioned HOF probability (e.g., cell-specific HOF probability) as output information of the artificial intelligence model.

[0099] In step 540, the terminal can predict / derive the aforementioned RLF probability (e.g., cell-specific RLF probability) as output information of the artificial intelligence model.

[0100] In step 545, the terminal can predict / derive the aforementioned TOS value (e.g., TOS value per cell) as output information of the artificial intelligence model.

[0101] In step 547, the terminal can predict / derive the probability of the aforementioned specific event (e.g., Event A3 or Event X' or RLF or HOF) as output information of the artificial intelligence model.

[0102] In step 548, the terminal can predict / derive the occurrence time or section of the aforementioned specific event (e.g., Event A3 or Event X') or RLF or HOF as output information of the artificial intelligence model.

[0103] In step 550, the terminal can derive setting parameter information that can be used at a future point in time or at a value derivation point in time as output information of the artificial intelligence model.

[0104] For example, the terminal may use the derived values ​​instead of the layer-specific (e.g., RRC, SDAP, PDCP, RLC, MAC, PHY) configuration information and parameter values ​​set by the base station or the network and / or the configuration information and parameter values ​​set by the AMF through NAS signaling.

[0105] FIG. 6 is a diagram illustrating a procedure for performing handover between a terminal and a base station according to one embodiment of the present disclosure.

[0106] In step 605, the base station may transmit a UE capability enquiry message requesting the transmission of support capability (e.g., Capability) information to a terminal in connected mode. Upon receiving this message, the terminal may transmit a UE capability information message containing the terminal's support capability information to the base station. At this time, the UE capability information message may include support capability information of the terminal related to the terminal performing a handover (e.g., presence or absence of support capability).

[0107] In step 607, the terminal in connected mode can receive configuration information regarding cell measurement report (e.g., Measurement report or MR) from the base station through an RRC Reconfiguration message.

[0108] In step 610, the terminal may perform cell measurement according to configuration information regarding cell measurement report (e.g., Measurement report or MR) and report the resulting generated measurement report information to the base station via a Measurement Report message.

[0109] In step 615, the base station or source base station may transmit a HANDOVER REQUEST message requesting a handover of the terminal to the target base station. The source base station may decide to transmit the HANDOVER REQUEST message after receiving a cell measurement report from the terminal (e.g., after receiving a measurement report triggered by event A3).

[0110] In step 620, the target base station that received the HANDOVER REQUEST message may transmit a HANDOVER REQUEST ACKNOWLEDGE message to the source base station to allow the handover of the terminal. The HANDOVER REQUEST ACKNOWLEDGE message may include configuration information about the target cell to which the terminal performs the handover.

[0111] At step 622, the source base station may start running Timer 1 (e.g., TXnRELOCoveral) after receiving the HANDOVER REQUEST ACKNOWLEDGE message.

[0112] In step 625, the source base station may transmit target cell configuration information to the terminal via an RRC Reconfiguration message (e.g., including a reconfigurationWithSync configuration).

[0113] At step 627, the terminal may start running the T304 timer after receiving the RRC Reconfiguration message.

[0114] In step 630, the terminal may receive an RRC Reconfiguration message including target cell configuration information and then attempt a handover to the target cell using the configuration information. To this end, the terminal may perform random access to the target cell and transmit an RRC Reconfiguration Complete message to the target cell.

[0115] In step 632, if the terminal successfully completes random access, T304 may be terminated. If the terminal fails to successfully complete random access, T304 may expire and the terminal may perform an RRC Re-establishment procedure.

[0116] In step 635, the target base station may transmit a UE CONTEXT RELEASE (COMMAND) message to the source base station to notify the source base station of a successful handover. Before transmitting the UE CONTEXT RELEASE (COMMAND) message, the target base station may change the downlink data path and establish an NG interface by exchanging a PATH SWITCH REQUEST message (e.g., a message transmitted from the target base station to the AMF) and a PATH SWITCH REQUEST ACKNOWLEDGE message (e.g., a message transmitted from the AMF to the target base station) with the AMF.

[0117] At step 637, the source base station may release the configuration information or context regarding the terminal after receiving the UE CONTEXT RELEASE (COMMAND) message (e.g., after a successful handover). The source base station may stop the timer 1 (e.g., TXnRELOCoveral) after receiving the UE CONTEXT RELEASE (COMMAND) message.

[0118] In one embodiment of the present disclosure, if the terminal reconnects to the source base station or source cell (e.g., after a handover failure) before the timer expires (e.g., before receiving a UE CONTEXT RELEASE message), the source base station may stop Timer 1.

[0119] In one embodiment of the present disclosure, if timer 1 expires (e.g., if the source base station did not release the configuration information or context regarding the terminal before timer 1 expired), the source base station may release the configuration information or context regarding the terminal.

[0120] In one embodiment of the present disclosure, if timer 1 expires (e.g., if the source base station did not release the configuration information or context regarding the UE before timer 1 expires), the source base station may request the AMF to release the UE-associated configuration and connection (UE-associated logical NG-connection) information. That is, timer 1 may be a timer for the source base station and / or the AMF to release the configuration and / or connection and / or context information regarding the UE without continuing to store it (e.g., when the UE connects to another base station through an RRC Reestablishment procedure after a handover failure).

[0121] FIG. 7 is a diagram illustrating a procedure for performing a handover based on prediction and related reporting using an artificial intelligence model between a terminal and a base station according to one embodiment of the present disclosure.

[0122] In step 705, the base station may transmit a UE capability enquiry message requesting transmission of support capability (e.g., Capability) information to a terminal in connected mode. Upon receiving this, the terminal may transmit a UE capability information message containing the terminal's support capability information to the base station. At this time, the UE capability information message may include at least one of the following terminal support capability information (information 1 to 8).

[0123] - Information 1. Whether the terminal supports prediction and / or reporting of HOF-related information (e.g., HOF probability) (using artificial intelligence)

[0124] - Information 2. Whether the terminal supports prediction and / or reporting of RLF-related information (e.g., RLF probability) (using artificial intelligence)

[0125] - Information 3. Whether the terminal supports prediction and / or reporting of TOS-related information (e.g., RLF probability) (using artificial intelligence)

[0126] - Information 4. Whether the terminal supports prediction and / or reporting of handover-related information (e.g., handover interruption time) (using artificial intelligence). Handover interruption time may refer to the time during which uplink and / or downlink data transmission is temporarily interrupted during handover from the source base station to the target base station.)

[0127] - Information 5. Whether the terminal supports a response (e.g., handover acceptance or rejection, or preference for handover acceptance or preference for handover rejection) to a handover instruction (e.g., RRC Reconfiguration message including reconfigurationWithSync) (using artificial intelligence).

[0128] - Information 6. Whether the terminal supports requests for desired or preferred network settings (using artificial intelligence)

[0129] - Information 7. Whether the terminal supports an action to perform prediction and / or related reporting on (existing or new) events (e.g., Event A3 or Event X' or RLF or HOF) (e.g., based on measured / predicted values ​​or information) (using artificial intelligence)

[0130] - Information 8. Whether the terminal supports prediction and / or reporting of information (e.g., probability of event occurrence or predicted time of event occurrence) related to an event (e.g., Event A3 or Event X' or RLF or HOF) (using artificial intelligence)

[0131] A terminal can indicate to a base station that it supports a specific capability by including or setting (e.g., setting to “true”) a specific indicator of the capability in a UE capability information message. A terminal can indicate to a base station that it does not support a specific capability by omitting or setting (e.g., setting to “false”) a specific indicator of the capability in a UE capability information message.

[0132] In step 710, the base station may transmit cell measurement report related settings to the terminal (e.g., via MeasConfig in an RRC Reconfiguration message). For example, the base station may provide the terminal with cell measurement report settings associated with event A3.

[0133] In one embodiment, if the terminal supports the artificial intelligence-based prediction capability (described above in 705), the base station may set a prediction request and / or prediction request-related settings for the terminal together with or including the cell measurement report settings. The prediction request-related settings may include at least one of the following information (information 1 to 9).

[0134] - Information 1. HOF probability threshold

[0135] - Information 2. RLF probability threshold

[0136] - Information 3. TOS threshold

[0137] - Information 4. The aforementioned reference time, for example, may be a value indicating an absolute time point in time. For example, this value may be a relative time value based on when the terminal received the cell measurement report related settings and / or the prediction request related settings (e.g., 710). For example, when the terminal received the cell measurement report related settings and / or the prediction request related settings at the absolute time of 10:05:03 and the reference time was set to 10 seconds, the reference time point, which is the time point predicted by the terminal, may be 10:05:13. Furthermore, in one embodiment, this value may be a relative time value based on when the terminal transmitted the cell measurement report and / or the prediction report (e.g., 715). For example, when the terminal receives a reference time set to 10 seconds in step 710 and transmits a cell measurement report and / or a prediction report at an absolute time of 10:05:03 in step 715, the reference time, which is the time point predicted by the terminal, may be 10:05:13. After receiving the cell measurement report and / or the prediction report in step 715, the base station may perform an operation of determining and preparing a handover of the terminal by using the same (e.g., exchanging a HANDOVER REQEUST and a HANDOVER REQUEST ACKNOWLEDGEMENT with the target cell through the Xn interface, steps 725 and 730), and an operation of transmitting a handover instruction to the terminal (e.g., an RRC Reconfiguration message including a reconfigurationwithsync, step 735) for a reference time length (e.g., 10 seconds). That is, the reference time (e.g., 10:05:13) predicted by the terminal and the time (e.g., 10:05:13) at which the base station issues a handover instruction may coincide. For example, if the reference time is 10 seconds, the base station can perform operations from 715 to 735 over a 10-second period. Through this, the terminal can perform predictions assuming that it will receive a handover instruction at the time indicated by the reference time.For example, a base station that receives a prediction report (predicting the time point of 10:05:13) transmitted from a terminal at 10:05:03 can complete a handover decision / preparation based on this for a reference time length of 10 seconds (from 10:05:03 to 10:05:13) and transmit a handover instruction to the terminal at 10:05:13.

[0138] In one embodiment, steps 712 and 715 may be performed almost simultaneously. That is, the terminal may perform prediction (e.g., step 712) and report the prediction result to the base station at the moment when the condition is triggered (e.g., step 715). Since the terminal continuously and repeatedly performs prediction, it can report the predicted result to the base station at the time closest to the time when the reporting condition is satisfied. Therefore, for example, if the reference time is 10 seconds, the terminal may perform prediction for a time point at least 10 seconds after the prediction, and the prediction result of the terminal may be a prediction for a time point 10 seconds after the time point reported to the base station.

[0139] Additionally, in one embodiment, steps 712 and 715 may be integrated, i.e., the terminal may perform prediction based on a reference time when a reporting condition is triggered, and report the prediction result to the base station. Since the difference between the time the terminal performs the prediction and the time it transmits the report is very small, the terminal may be considered to be predicting the result at a point in time that has elapsed from the time it transmits the report.

[0140] - Information 5. Whether to include each piece of information that the terminal can include in the prediction report, for example, the base station can instruct the terminal to include the corresponding prediction report information in the prediction report by including or setting (e.g., setting to "true") a specific indicator for each piece of information that can be included in the prediction report. For example, the base station can instruct the terminal not to include the corresponding prediction report information in the prediction report by omitting or setting (e.g., setting to "false") a specific indicator for each piece of information that can be included in the prediction report.

[0141] - Information 6. Length value for a timer (e.g., timer 2) related to prediction and / or related reporting of the terminal, for example, if the terminal receives a length value for timer 2, the terminal may start timer 2 upon receiving a prediction request related configuration. If the terminal performs or finishes reporting (e.g., 715) on the prediction request, the timer 2 may be terminated. If the terminal does not perform reporting on the prediction request until timer 2 expires (i.e., upon timer expiration), the terminal may no longer perform prediction and / or related reporting or may not include it in the cell measurement report (e.g., 715). If the terminal does not perform reporting on the prediction request until timer 2 expires (i.e., upon timer expiration), the terminal may release the prediction request related configuration.

[0142] - Information 7. Event setting information and parameters required for the terminal to perform prediction and / or related reporting on (existing or new) events (e.g., Event A3 or Event X' or RLF or HOF) (e.g., based on measured / predicted values ​​or information) (using artificial intelligence).

[0143] Prediction request related settings may be transmitted to the terminal by being included in an RRC Reconfiguration message, a UE Information Request message, or a new RRC message. In one embodiment of the present disclosure, the prediction request related settings may be transmitted to the terminal from an AMF or OAM (e.g., via NAS signaling) rather than from a base station.

[0144] - Information 8. The aforementioned reference time interval. For example, the base station may indicate the nearest future time point (lower bound) and / or the furthest future time point (upper bound) within the time interval. For example, each time point may be indicated as an absolute time point. For example, similar to the aforementioned reference time, each time point may be a relative time value based on when the terminal received the cell measurement report-related configuration and / or prediction request-related configuration (e.g., 710). Additionally, each time point may be a relative time value based on when the terminal transmitted the cell measurement report and / or prediction report (e.g., 715).

[0145] In one embodiment of the present disclosure, a base station may indicate a reference time interval by indicating a time period from a fixed point in time. For example, the fixed point in time may be a point in time at which the terminal receives prediction and / or measurement-related settings (e.g., 710), a point in time at which the terminal performs prediction or derives a prediction value (e.g., 712), or a point in time at which the terminal performs prediction and / or measurement reporting (e.g., 715).

[0146] - Information 9. Threshold probability of occurrence of an event (e.g., Event A3 or Event X' or RLF or HOF)

[0147] In step 712, the terminal can predict / derive information to be used in the prediction report (715) by running an artificial intelligence model based on the prediction request related setting information (710).

[0148] In step 715, the terminal may report predicted / derived information to the base station (e.g., prediction report or prediction report) if at least one of the following conditions (conditions 1 to 22) is satisfied.

[0149] - Condition 1. If the prediction request-related settings are linked to a cell measurement report, and the cell measurement report is triggered (e.g., if an event set for the cell measurement report is triggered or a periodic cell measurement report is set / triggered).

[0150] - Condition 2. When an event set to predictive reporting is triggered or when periodic predictive reporting is set / triggered.

[0151] - Condition 3. When the predicted / derived HOF probability for the target cell is greater than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard). If a prediction report is triggered under this condition, the base station can know that HOF will occur with a relatively high probability when the terminal performs a handover to a specific cell, so this can be useful information for the base station to decide / instruct the terminal to handover to the corresponding cell. For example, the base station may not decide / instruct the terminal to handover to the corresponding cell.

[0152] - Condition 4. When the predicted / derived HOF probability is less than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard). If the predicted report is triggered under this condition, the base station can know that the HOF will occur with a relatively low probability when the terminal performs a handover to a specific cell, so this can be useful information for the base station to decide / instruct the terminal to handover to the corresponding cell. For example, the base station can decide / instruct the handover to the corresponding cell.

[0153] - Condition 5. When the predicted / derived RLF probability is greater than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard). If a prediction report is triggered under this condition, the base station can know that RLF will occur with a relatively high probability when the terminal performs a handover to a specific cell (or stays in the current cell), so this can be useful information for the base station to decide / instruct the terminal to handover to the corresponding cell (or stay in the current cell). For example, the base station may not decide / instruct the terminal to handover to the corresponding cell.

[0154] - Condition 6. When the predicted / derived RLF probability is less than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard). When the predicted report is triggered under this condition, the base station can know that RLF will occur with a relatively low probability when the terminal performs a handover to a specific cell (or stays in the current cell), so this can be useful information for the base station to decide / instruct the terminal to handover to the corresponding cell (or stay in the current cell). For example, the base station can decide / instruct the handover to the corresponding cell.

[0155] - Condition 7. When the predicted / derived TOS value is less than a certain threshold value (e.g., a threshold value set by the base station in 710 or a fixed value defined in the standard). When the predicted reporting is triggered by this condition, the base station can know that the TOS will be relatively low (e.g., another handover is required) when the terminal performs a handover to a specific cell (or stays in the current cell), so this can be useful information for the base station to decide / instruct the terminal to handover to that cell (or stay in the current cell). For example, the base station may not decide / instruct the terminal to handover to that cell.

[0156] - Condition 8. When the predicted / derived TOS value is greater than a certain threshold value (e.g., a threshold value set by the base station in 710 or a fixed value defined in the standard). When the predicted reporting is triggered by this condition, the base station can know that the TOS will be relatively large (e.g., no further handover is required) when the terminal performs a handover to a specific cell (or stays in the current cell), so this can be useful information for the base station to decide / instruct the terminal to handover to the corresponding cell (or stay in the current cell). For example, the base station can decide / instruct the handover to the corresponding cell.

[0157] - Condition 9. If HOF is predicted when performing a handover.

[0158] - Condition 10. When RLF is predicted when performing a handover to a specific cell (or staying in the current cell).

[0159] - Condition 11. When a short TOS is expected when performing a handover to a specific cell (or staying in the current cell), or when a handover ping-pong (e.g. between two cells or between multiple cells) is expected.

[0160] - Condition 12. If the terminal receives a setting regarding a prediction (report) request (e.g., in the reportConfig setting).

[0161] - Condition 13. If the events set based on the predicted cell measurement values ​​(instead of the actual cell measurement values) (e.g. Event A1, A2, A3, A4, A5, A6, B1, B2) are satisfied.

[0162] - Condition 14. If a (previous or new) event (e.g., Event A3 or Event X' or RLF or HOF) is predicted or detected (e.g., based on measured / predicted values ​​or information).

[0163] - Condition 15. If the predicted value for the target (candidate) cell (e.g., RLF probability) (or this value plus an offset value) is less than the predicted value for the source cell (e.g., RLF probability).

[0164] - Condition 16. If the predicted value for the target (candidate) cell (e.g., RLF probability) is greater than the predicted value for the source cell (e.g., RLF probability) (or even if an offset value is added to this value).

[0165] - Condition 17. If the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the target (candidate) cell is greater than the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the source cell (or even if an offset value is added to this value).

[0166] - Condition 18. If the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the target (candidate) cell (or this value plus an offset value) is less than the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the source cell.

[0167] - Condition 19. If the probability of occurrence of a predicted / derived event (e.g., Event A3 or Event X' or RLF or HOF) is greater than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0168] - Condition 20. If the occurrence time of the predicted / derived event (e.g., Event A3 or Event X' or RLF or HOF) is within the reference point or interval.

[0169] - Condition 21. If the predicted event or predicted value is (successfully) derived.

[0170] - Condition 22. If the probability of occurrence of a predicted / derived event (e.g., Event A3 or Event X' or RLF or HOF) is less than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0171] If the conditions are not met, the terminal may not report the predicted / derived information to the base station (e.g., a prediction report). In this case, the terminal may only transmit cell measurement values ​​(e.g., not including the prediction report) to the base station.

[0172] The prediction report transmitted by the terminal may include at least one of the following pieces of information (information 1 to 15).

[0173] - Information 1. (For the event that triggered the measurement report, or among the cells that triggered the measurement report) a list of one or more cells with a predicted HOF probability higher than a threshold (e.g., set by the base station or fixed in the standard) and related information (e.g., cell ID). For example, a base station that receives this information may not decide / instruct a handover to the corresponding cell.

[0174] - Information 2. A list of one or more cells with a predicted RLF probability higher than a threshold (e.g., set by the base station or fixed in the standard) (or predicted to have RLF) (for the event that triggered the measurement report, or among the cells that triggered the measurement report) and related information (e.g., cell ID). For example, a base station that receives this information may not decide / instruct a handover to the corresponding cell.

[0175] - Information 3. A list of one or more cells (e.g., cell IDs) with a predicted TOS value lower than a threshold (e.g., set by the base station or fixed in the standard) (or for which a handover ping-pong is expected) for the event that triggered the measurement report, or among the cells that triggered the measurement report. For example, a base station that receives this information may not decide / instruct a handover to the corresponding cell.

[0176] - Information 4. (For the event that triggered the measurement report, or among the cells that triggered the measurement report) A list of one or more cells with a predicted HOF probability lower than a threshold (e.g., set by the base station or fixed in the standard) (or for which HOF is not predicted) and related information (e.g., cell ID). For example, a base station that receives this information can decide / instruct a handover to the corresponding cell.

[0177] - Information 5. (For the event that triggered the measurement report, or among the cells that triggered the measurement report) A list of one or more cells with a predicted RLF probability lower than a threshold (e.g., set by the base station or fixed in the standard) (or where RLF is predicted) and related information. For example, a base station that receives this information can decide / instruct a handover to the corresponding cell.

[0178] - Information 6. (For the event that triggered the measurement report, or among the cells that triggered the measurement report) A list of one or more cells with a predicted TOS value higher than a threshold (e.g., set by the base station or fixed in the standard) (or for which a handover ping-pong is not expected) and related information (e.g., cell ID). For example, a base station that receives this information can decide / instruct a handover to the corresponding cell.

[0179] - Information 7. (For each cell) Whether a high HOF probability, a high RLF probability, or a low TOS is predicted. If the indicator related to this information is included in the prediction report or set to a specific value (e.g., “true”), this may mean / indicate that a high HOF probability, a high RLF probability, or a low TOS is predicted (for each cell). If the indicator related to this information is omitted from the prediction report or set to a specific value (e.g., “false”), this may mean / indicate that a low HOF probability, a low RLF probability, or a high TOS is predicted (for each cell).

[0180] - Information 8. (On a cell-by-cell basis) Whether HOF or RLF or handover ping-pong is expected. If the corresponding information-related indicator is included in the prediction report or set to a specific value (e.g., “true”), this may mean / indicate that HOF or RLF or handover ping-pong is expected (on a cell-by-cell basis). If the corresponding information-related indicator is omitted in the prediction report or set to a specific value (e.g., “false”), this may mean / indicate that HOF or RLF or handover ping-pong is not expected (on a cell-by-cell basis).

[0181] - Information 9. (For each cell) Predicted HOF probability or RLF probability or TOS value

[0182] - Information 10. (Cell-by-cell) Expected interruption time

[0183] - Information 11. (Cell-by-cell) Predicted cell measurements (e.g., RSRP, RSRQ, SINR)

[0184] - Information 12. (by cell) Terminal preference for handover (e.g., accept or reject)

[0185] - Information 13. (For each cell) Setting information (desired or preferred) by the terminal when assuming handover

[0186] - Information 14. (by cell) Event predicted / detected by the terminal, or measured / predicted value or information that triggered the event predicted / detected by the terminal.

[0187] - Information 15. (For each cell) Event probability predicted / detected by the terminal, or predicted event occurrence time and interval

[0188]

[0189] The prediction report can be transmitted to the base station via a Measurement Report message, a UE Information Response message, a UE Assistance Information message, or a new RRC message.

[0190] In one embodiment of the present disclosure, a new event may be defined to trigger cell measurement and / or prediction reporting. This may be configured in the terminal when requesting cell measurement configuration and / or prediction (e.g., reportConfig). For example, a new event called Event X' may be defined, and Event X' may be an event that is triggered when at least one of the following events (Events 1 and 2) is satisfied or triggered.

[0191] - Event 1. When Event X (e.g. Event A1, A2, A3, A4, A5, A6, B1, B2) based on cell measurement is triggered.

[0192] - Event 2. When a prediction / measurement-based condition (e.g., if the predicted HOF probability is higher or lower than the threshold, the conditions listed in 715 above) is satisfied.

[0193] In one embodiment of the present disclosure, the terminal may transmit cell measurement and / or prediction reports either one-time (e.g., upon configured event trigger) or periodically (e.g., according to network settings).

[0194] At step 720, the source base station may determine the target cell to which the terminal will be handed over. For example, the determination may be made based on the cell measurement and / or prediction report transmitted by the terminal at step 715.

[0195] The operations from steps 725 to 740 thereafter refer to the aforementioned steps from steps 615 to 637 of FIG. 6 and the related descriptions, and any redundant descriptions are omitted here.

[0196] FIG. 8 is a diagram illustrating a procedure for performing a handover based on prediction and related reporting using an artificial intelligence model between a terminal and a base station according to one embodiment of the present disclosure.

[0197] For the operation for step 805, refer to the description related to the operation (part or all) for step 705 of FIG. 7, and any duplicate description is omitted here.

[0198] For the operation for step 810, refer to the description related to the operation (part or all) for step 607 of FIG. 6, and any duplicate description is omitted here.

[0199] For the operation for step 815, refer to the description related to the operation (part or all) for step 610 of FIG. 6, and any duplicate description is omitted here.

[0200] In step 820, the base station may determine one or more target candidate cells or target candidate base stations to which to transmit a prediction request before handing over the terminal based on the cell measurement report received from the terminal. For example, instead of instructing the terminal to perform a prediction request for all surrounding cells, the base station may instruct the terminal to perform a prediction request only for some best neighboring cells (e.g., cells with the highest RSRP) based on the cell measurement report. This is because the process of the terminal running an artificial intelligence model to perform a prediction and reporting the result to the base station may result in the use and overload of a significant amount of computing resources and power (energy) resources, as well as radio resources for transmission and reception, compared to conventional wireless communication technologies, and therefore, it may be desirable for the base station to transmit such prediction requests only for some cells.

[0201] The operation for step 825 refers to the description related to the operation (partial or entire) related to the prediction request for step 710 of FIG. 7, and the redundant description is omitted here. In one embodiment of the present disclosure, the base station can request the prediction request separately from the cell measurement configuration. In one embodiment of the present disclosure, the message used for the cell measurement configuration (e.g., the RRC Reconfiguration message) and the message used for the prediction request may be different. In one embodiment of the present disclosure, the message used for the prediction request may be an RRC Reconfiguration / RRC Resume / new RRC message. In step 825, the base station can transmit the prediction request for one or more target candidate cells, and can transmit related information (e.g., cell ID) for the target candidate cells together.

[0202] The operation for step 830 refers to the description related to the operation (partial or entire) for step 712 of FIG. 7, and redundant descriptions are omitted here. In one embodiment of the present disclosure, the terminal can derive information to be used for prediction reporting for each target candidate cell set in step 825.

[0203] The operation for step 835 refers to the description of the operation (partial or entire) related to the prediction report for step 715 of FIG. 7, and the redundant description is omitted here. In one embodiment of the present disclosure, the terminal can transmit a prediction report including the above-described prediction report information (for each target candidate cell set in step 825) when the above-described prediction report transmission condition is satisfied (for each target candidate cell set in step 825).

[0204] In step 840, the source base station may determine the target cell to which the terminal will be handed over. For example, this may be determined based on the cell measurement and / or prediction report transmitted by the terminal in step 815 and / or step 825.

[0205] The operations from steps 845 to 860 thereafter refer to the description of the operations (part or all) of the aforementioned steps from steps 615 to 637 of FIG. 6, and any redundant description is omitted here.

[0206] FIG. 9 is a diagram illustrating a procedure for performing a handover based on prediction and related reporting using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0207] For the operation for step 905, refer to the description related to the operation (part or all) for step 705 of FIG. 7, and redundant description is omitted here.

[0208] The operation for step 910 refers to the description related to the operation (part or all) for step 607 of FIG. 6, and redundant description is omitted here.

[0209] The operation for step 915 refers to the description related to the operation (part or all) for step 610 of FIG. 6, and redundant description is omitted here.

[0210] In step 917, the base station may determine one or more target candidate cells or target candidate base stations to which to transmit a prediction request before handing over the terminal based on the cell measurement report received from the terminal. For example, instead of instructing the terminal to perform a prediction request for all surrounding cells, the base station may instruct the terminal to perform the prediction request only for some best neighboring cells (e.g., cells with the highest RSRP) based on the cell measurement report. This is because the process of the terminal running an artificial intelligence model to perform a prediction and reporting the result to the base station may result in the use and overload of a significant amount of computing resources and power (energy) resources, as well as radio resources for transmission and reception, compared to conventional wireless communication technologies, and therefore, it may be desirable for the base station to transmit such prediction requests only for some cells.

[0211] In FIG. 8, the base station transmits a prediction request for a target candidate cell to the terminal (step 825), the terminal performs prediction (step 830), and transmits the prediction result to the base station via a prediction report (step 835). Thereafter, the base station determines a target cell (step 840) and transmits a handover request (step 845) to the target base station. However, at this time, the target base station may not permit the handover request (e.g., by replying a HANDOVER PREPARATION FAILURE message). In this case, a series of (prediction-related) operations (steps 825, 830, and 835) of the terminal and the base station for the target cell may be meaningless operations, which may result in a waste of computing, wireless, and energy resources of the terminal and the base station. To address this issue, in FIG. 1i, before transmitting a prediction request (step 945) for the determined target candidate cell (step 917), the source base station may transmit a handover request (e.g., by transmitting a HANDOVER REQUEST message) for each target candidate cell and receive an authorization for the handover request (e.g., by receiving a HANDOVER REQUEST ACKNOWLEDGE message) (steps 920, 925, 930, and 935). In steps 920 and 925, the source base station may transmit a handover request (e.g., by transmitting a HANDOVER REQUEST message) for each target candidate cell. At this time, the source base station may indicate that the handover request is a prediction-based handover request. For example, a prediction-based handover request can be indicated by including a specific indicator (or related setting) in the HANDOVER REQUEST message or setting it to a specific value (e.g., “true”), and a non-prediction-based handover request can be indicated by omitting the indicator (or related setting) or setting it to a specific value (e.g., “false”).This may be to prevent a target candidate cell that does not support or permit a prediction-based handover from permitting the prediction-based handover request (e.g., by replying a HANDOVER PREPARATION FAILURE message). For example, a prediction-based handover, unlike a conventional handover, may incur additional time delay due to prediction-related operations (steps 945, 950, and 955) and may be later canceled (step 970) even if the target candidate base station permits the request, so the target candidate base station may not support or permit it.

[0212] In steps 930 and 935, the source base station may receive permission for the handover request (e.g., by receiving a HANDOVER REQUEST ACKNOWLEDGE message) as a response to the handover request (e.g., by transmitting a HANDOVER REQUEST message) for each target candidate cell. The HANDOVER REQUEST ACKNOWLEDGE message may include configuration information about the target cell to which the terminal performs the handover. The terminal may store the target cell configuration information for each target candidate cell.

[0213] A target candidate base station can indicate permission for a prediction-based handover request for each target candidate cell. For example, a target candidate base station can indicate permission for a prediction-based handover request by including a specific indicator (or related setting) in a HANDOVER REQUEST ACKNOWLEDGE message or setting it to a specific value (e.g., “true”). For example, a target candidate base station can indicate disapproval for a prediction-based handover request by omitting a corresponding indicator (or related setting) in the HANDOVER REQUEST ACKNOWLEDGE message or setting it to a specific value (e.g., “false”). For example, a target candidate base station can indicate permission for a prediction-based handover request by replying a HANDOVER REQUEST ACKNOWLEDGE message, and can indicate disapproval for a prediction-based handover request by replying a HANDOVER PREPARATION FAILURE message.

[0214] In one embodiment of the present disclosure, the target base station may indicate to the source base station permission for a conventional handover (e.g., by including configuration information for the target cell in a HANDOVER REQUEST ACKNOWLEDGE message) even if the target base station indicates disallowance of a prediction-based handover request.

[0215] In step 937, if the source base station is instructed to allow the prediction-based handover request, the source base station may start running a new timer (e.g., timer 3 or TXnRELOCoveral_prediction). If the source base station is instructed to disallow the prediction-based handover request, the source base station may not start running a new timer (e.g., timer 3 or TXnRELOCoveral_prediction). The length of the timer 3 that the source base station runs may be a longer value than the conventional timer 1 (e.g., a value set by OAM or a fixed value defined in the standard). This is because the prediction-based handover may take longer time (e.g., 945, 950, 955) than the conventional handover.

[0216] At step 940, the source base station may select some or all of the target candidate cells (e.g., based on cell measurement result reports) that have been instructed to grant permission for the prediction-based handover request.

[0217] In step 945, the source base station may transmit a prediction request for the target candidate cells selected in step 940 to the terminal. The operation for step 945 refers to the description of the operation (partial or entire) related to the prediction request for step 825 of FIG. 8, and redundant description is omitted here.

[0218] The operation for step 950 refers to the description related to the operation (partial or entire) for step 830 of FIG. 8, and redundant descriptions are omitted here. In one embodiment of the present disclosure, the terminal can derive information to be used for prediction reporting for each target candidate cell set in step 945.

[0219] The operation for step 955 refers to the description related to the operation (partial or entire) for step 835, and the redundant description is omitted here. In one embodiment of the present disclosure, the terminal can transmit a prediction report including the above-described prediction report information (for each target candidate cell set in step 945) when the above-described prediction report transmission condition is satisfied (for each target candidate cell set in step 945).

[0220] In step 960, the source base station may determine the target cell to which the terminal will be handed over. For example, the source base station may determine the target cell to which the terminal will be handed over based on the cell measurement and / or prediction report transmitted by the terminal in step 915 and / or step 955.

[0221] In step 965, the source base station can transmit to the terminal an RRC Reconfiguration message including the target cell configuration information stored in step 930.

[0222] In step 970, the source base station may request (e.g., by transmitting a HANDOVER CANCEL message) to cells among the target candidate cells that are not determined as the target cell (the target cell determined in step 960). This may be for the purpose of releasing the settings and resources allocated by the cells for the handover of the terminal without further maintenance. In one embodiment of the present disclosure, the source base station may perform the operation for step 970 at a time point between (or after) steps 965 and 985.

[0223] In step 975, the terminal may receive the RRC Reconfiguration message including target cell configuration information and may attempt a handover to the target cell using the configuration information. To this end, the terminal may perform random access to the target cell and transmit an RRC Reconfiguration Complete message.

[0224] In step 980, the target base station may indicate the success of the handover to the source base station (e.g., by transmitting a HANDOVER SUCCESS message) (e.g., after a successful handover of the UE or after receiving an RRC Reconfiguration Complete message). Alternatively, the target base station may transmit a UE CONTEXT RELEASE (COMMAND) message to inform the source base station of the successful handover. The target base station may change the downlink data path and establish the NG interface by exchanging a PATH SWITCH REQUEST message (e.g., a message transmitted by the target base station to the AMF) and a PATH SWITCH REQUEST ACKNOWLEDGE message (e.g., a message transmitted by the AMF to the target base station) before transmitting the UE CONTEXT RELEASE (COMMAND) message.

[0225] In step 985, the source base station may release configuration information or context regarding the terminal after receiving a UE CONTEXT RELEASE (COMMAND) message or a HANDOVER SUCCESS message from the target cell or the target base station (e.g., after a successful handover). The source base station may stop Timer 3 for the corresponding cell after receiving a UE CONTEXT RELEASE (COMMAND) message or a HANDOVER SUCCESS message from the target cell or the target base station.

[0226] In one embodiment of the present disclosure, if the terminal reconnects to the source base station or source cell (e.g., after a handover failure) before the timer expires (e.g., before receiving a UE CONTEXT RELEASE message), the source base station may stop Timer 3.

[0227] In one embodiment of the present disclosure, if timer 3 expires (e.g., if the source base station did not release the configuration information or context regarding the terminal before timer 3 expired), the source base station may release the configuration information or context regarding the terminal.

[0228] In one embodiment of the present disclosure, if timer 3 expires (e.g., if the source base station did not release the configuration information or context regarding the UE before timer 3 expires), the source base station may request the AMF to release the UE-associated configuration and connection (UE-associated logical NG-connection) information. That is, timer 3 may be a timer for the source base station and / or the AMF to release the configuration and / or connection and / or context information regarding the UE without continuing to store it (e.g., when the UE connects to another base station through an RRC Reestablishment procedure after a handover failure).

[0229] In one embodiment of the present disclosure, a base station (e.g., step 715, step 835) that receives a prediction report including prediction information (e.g., predicted HOF probability, predicted RLF probability, predicted TOS value) from a terminal can transmit this prediction information to a target candidate base station. For example, this information can be included and transmitted when sending a HANDOVER REQUEST (e.g., step 725, step 845) or a new Xn interface message. For example, the target candidate base station that received this can make a decision by considering this information when deciding whether to permit or reject a handover request from the terminal.

[0230] In one embodiment of the present disclosure described above (e.g., FIGS. 7 and 8 and 1i), a terminal may perform prediction using artificial intelligence and transmit the resulting prediction results to a base station via a prediction report. Thereafter, the base station may instruct the terminal to perform a handover (e.g., by determining a target cell) via the received prediction report.

[0231] In one embodiment of the present disclosure, a terminal can make a handover-related decision or perform an action after performing a prediction using artificial intelligence without a prediction report. For example, the terminal and base station can perform an action as described below.

[0232] - Embodiment 1. After receiving a handover indication (e.g., to target cell 1) from a base station, the terminal performs prediction, and based on the prediction result (e.g., when the HOF probability is low), accepts the handover indication and performs handover (e.g., to target cell 1). This may be an embodiment corresponding to FIG. 1j and the related description.

[0233] - Embodiment 2-1. After receiving a handover indication (e.g., to target cell 1) from a base station, the terminal performs prediction, and based on the prediction result (e.g., when the HOF probability is low), accepts the handover indication and performs the handover, and based on the new prediction result (e.g., when the HOF probability is high), the terminal can stop the handover (e.g., to target cell 1) and perform an RRC Re-establishment procedure (e.g., before timer T304 / T310 / T312 or RLF detection / declaration). By performing the RRC Re-establishment procedure in advance, the terminal can quickly find and connect to a new cell (e.g., target cell 2) before a problem (e.g., RLF or Handover failure) occurs. This may be an embodiment corresponding to FIG. 1k and the related description.

[0234] - Embodiment 2-2. After receiving a handover indicator from the base station (e.g., to target cell 1), the terminal may perform a handover, and then, based on the prediction result (e.g., when the HOF probability is high), the handover may be stopped (e.g., before timer T304 / T310 / T312 or RLF detection / declaration) and an RRC Re-establishment procedure may be performed. By performing the RRC Re-establishment (RRE) procedure in advance, the terminal may quickly find and connect to a new cell (e.g., target cell 2) before a problem (e.g., RLF or handover failure) occurs. This may be an embodiment corresponding to FIG. 1k and the related description.

[0235] - Embodiment 3. After receiving a handover indication (e.g., to target cell 1) from the base station, the terminal performs prediction, and rejects the handover indication based on the prediction result (e.g., when the HOF probability is high) and notifies the base station of this, so that the base station can find a new target cell (e.g., target cell 2) and instruct the terminal to perform a new handover. The terminal can be instructed to a new target cell (e.g., target cell 2) from the base station before the problem occurs by predicting a problem (e.g., RLF or handover failure) in advance and notifying the base station of this. This may be an embodiment corresponding to FIG. 11 and the related description.

[0236] - Embodiment 4. After receiving a handover indication from the base station (e.g., to target cell 1), the terminal may perform prediction, and based on the prediction result (e.g., when the HOF probability is high), reject the handover indication and notify the base station of this. However, at this time, the base station may still determine that it is desirable to handover the terminal to the target cell (e.g., target cell 1). In this case, the base station may transmit an indication to the terminal not to allow the handover rejection by the terminal, and the terminal may receive this and perform a handover to the existing target cell (e.g., to target cell 1). This may be an embodiment corresponding to FIG. 1m and the related description.

[0237] - Embodiment 5. After receiving a handover indication from the base station (e.g., to target cell 1), the terminal may perform a prediction and postpone (postpone) the handover based on the prediction result (e.g., when the HOF probability is high). For example, the terminal may predict / judge that postponing the handover may lower the HOF probability. This may be an embodiment corresponding to FIG. 1n and the related description.

[0238] FIG. 10 is a diagram illustrating a procedure for performing prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0239] The operation for step 1005 refers to the description related to the operation (partial or entire) for step 705 of FIG. 7, and the redundant description is omitted here. Alternatively, the UE capability information message may include at least one of the following UE support capability information (information 1 to 2).

[0240] - Information 1. Whether the terminal supports the ability to accept and / or reject and / or postpone a handover instruction from the base station based on predictions (e.g., predictions for HOF and / or RLF and / or TOS and / or cell measurement values ​​and / or events) (using artificial intelligence)

[0241] - Information 2. Whether the terminal supports the ability to perform fast RRE during or before / after performing a handover instruction from the base station based on prediction (e.g., prediction of HOF and / or RLF and / or TOS and / or cell measurement values ​​and / or events) using artificial intelligence.

[0242] For the operation for step 1010, refer to the description related to the operation (part or all) for step 607 of FIG. 6, and redundant description is omitted here.

[0243] For the operation for step 1015, refer to the description related to the operation (part or all) for step 610 of FIG. 6, and redundant description is omitted here.

[0244] In step 1020, the source base station may determine the target cell to which the terminal will be handed over. For example, the determination may be made based on the cell measurement and / or prediction report transmitted by the terminal in step 1015.

[0245] In step 1025, the source base station may transmit a handover request (e.g., by transmitting a HANDOVER REQUEST message) to the target (candidate) cell. At this time, the source base station may indicate that the handover request is a predictive-based handover request. For example, the predictive-based handover request may be indicated by including a specific indicator (or related setting) in the HANDOVER REQUEST message or setting it to a specific value (e.g., “true”), and the non-predictive-based handover request may be indicated by omitting the indicator (or related setting) or setting it to a specific value (e.g., “false”). This may be to prevent a target candidate cell that does not support or permit predictive-based handover from permitting the predictive-based handover request (e.g., by replying a HANDOVER PREPARATION FAILURE message). For example, unlike conventional handover, prediction-based handover incurs additional time delay due to prediction-related operations (steps 1050, 1055, and 1060) and may be later canceled (e.g., step 12105 when the terminal rejects the handover instruction in FIG. 12) even if the target candidate base station grants the request, so the target (candidate) base station may not support or grant it.

[0246] In step 1030, the source base station may receive permission for the handover request (e.g., by receiving a HANDOVER REQUEST ACKNOWLEDGE message) as a response to the handover request transmitted to the target (candidate) cell (e.g., by transmitting a HANDOVER REQUEST message). The HANDOVER REQUEST ACKNOWLEDGE message may include configuration information about the target cell to which the terminal performs handover.

[0247] In one embodiment of the present disclosure, the target base station may indicate to the source base station permission for a conventional handover (e.g., by including configuration information for the target cell in a HANDOVER REQUEST ACKNOWLEDGE message) even if the target base station indicates disallowance of a prediction-based handover request.

[0248] In step 1035, if the source base station is instructed to allow the prediction-based handover request, the source base station may start running a new timer (e.g., timer 3 or TXnRELOCoveral_prediction). If the source base station is instructed to disallow the prediction-based handover request, the source base station may not start running a new timer (e.g., timer 3 or TXnRELOCoveral_prediction). The length of the timer 3 that the source base station runs may be a longer value than the conventional timer 1 (e.g., a value set by OAM or a fixed value defined in the standard). This is because the prediction-based handover may take longer time (e.g., 1050, 1055, 1060) than the conventional handover.

[0249] In step 1040, if the source base station receives permission for a prediction-based handover request from the target base station, the source base station may transmit prediction request information (e.g., HOF / RLF probability threshold, TOS threshold, cell measurement value threshold) to the terminal together with a handover instruction (including the corresponding target cell configuration information). In an embodiment of the present disclosure, an offset value may be set in 1040 for comparison between a prediction value for a target (candidate) cell (e.g., RLF probability, TOS value, cell measurement prediction value) and a prediction value for a source cell (e.g., RLF probability, TOS value, cell measurement prediction value). In one embodiment of the present disclosure, a message used for the prediction request may be an RRC Reconfiguration / RRC Resume / new RRC message.

[0250] In one embodiment of the present disclosure, if a disallowance instruction is received for a prediction-based handover request, the source base station and the terminal and the target base station may perform a handover operation (e.g., operation from FIG. 622 onward) according to FIG. 6.

[0251] At step 1045, the terminal may start driving T304 (e.g., because it has received a handover instruction).

[0252] In step 1050, the terminal can derive prediction information (e.g., predicted HOF / RLF probability, predicted TOS value, cell measurement predicted value) by running an artificial intelligence model based on prediction request-related setting information (1040).

[0253] In step 1055, if the terminal satisfies at least one of the following conditions (conditions 1 to 12), the terminal may accept the handover instruction of the base station in step 1060.

[0254] - Condition 1. If the predicted / derived HOF probability is less than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0255] - Condition 2. When the predicted / derived RLF probability for the target cell is less than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0256] - Condition 3. When the predicted / derived value (e.g., RSRP, RSRQ, SINR, TOS value) for the target cell is greater than a specific threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0257] - Condition 4. When HOF is not predicted when performing a handover.

[0258] - Condition 5. When RLF is not expected when performing a handover to a specific cell (or when RLF is expected when staying in the current cell).

[0259] - Condition 6. If a long TOS is expected when performing a handover to a specific cell (or a short TOS is expected when staying in the current cell), or if a handover ping-pong (e.g., between two cells or between multiple cells) is not expected.

[0260] - Condition 7. If an event (e.g. Event A3) is satisfied (indicating that a handover needs to be performed) based on the predicted cell measurement value (instead of the actual cell measurement value).

[0261] - Condition 8. If a (previous or new) event (e.g. Event A3 or Event X' or RLF or HOF) is predicted or detected (e.g. based on measured / predicted values ​​or information) that implies the need to perform a handover.

[0262] - Condition 9. If the predicted value for the target (candidate) cell (e.g., RLF probability) (or even if an offset value is added to this value) is less than the predicted value for the source cell (e.g., RLF probability).

[0263] - Condition 10. If the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the target (candidate) cell is greater than the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the source cell (or even if an offset value is added to this value).

[0264] - Condition 11. If the probability of occurrence of a predicted / derived event (e.g., Event A3 or Event X') is greater than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0265] - Condition 12. If the occurrence time of the predicted / derived event (e.g., Event A3 or Event X') is within the reference point or interval.

[0266] In step 1065, the terminal may attempt handover to the target cell using the target cell configuration information received in step 1040. To this end, the terminal may perform random access to the target cell and transmit an RRC Reconfiguration Complete message.

[0267] For the operation for step 1070, refer to the description related to the operation (part or all) for step 632 of FIG. 6, and redundant description is omitted here.

[0268] For the operation for step 1075, refer to the description related to the operation (part or all) for step 635 of FIG. 6, and redundant description is omitted here.

[0269] For the operation for step 1080, refer to the description related to the operation (part or all) for step 985 of FIG. 9, and redundant description is omitted here.

[0270] FIG. 11 is a diagram illustrating a procedure for performing prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0271] The operation for step 1105 refers to the description related to the operation (partial or entire) for step 705 of FIG. 7, and the redundant description is omitted here. Alternatively, the UE capability information message may include at least one of the following UE support capability information (information 1 to 2).

[0272] - Information 1. Whether the terminal supports the ability to accept and / or reject and / or postpone a handover instruction from the base station based on predictions (e.g., predictions for HOF and / or RLF and / or TOS and / or cell measurement values ​​and / or events) (using artificial intelligence)

[0273] - Information 2. Whether the terminal supports the ability to perform fast RRE during or before / after performing a handover instruction from the base station based on prediction (e.g., prediction of HOF and / or RLF and / or TOS and / or cell measurement values ​​and / or events) using artificial intelligence.

[0274] The operation for step 1110 refers to the description related to the operation (part or all) for step 607 of FIG. 6, and redundant description is omitted here.

[0275] The operation for step 1115 refers to the description related to the operation (part or all) for step 610 of FIG. 6, and redundant description is omitted here.

[0276] At step 1120, the source base station may determine the target cell to which the terminal will be handed over. For example, this may be determined based on the cell measurement and / or prediction report transmitted by the terminal at step 1115.

[0277] For the operation for step 1125, refer to the description related to the operation (part or all) for step 1025 of FIG. 10, and redundant description is omitted here.

[0278] For the operation for step 1130, refer to the description related to the operation (part or all) for step 1030 of FIG. 10, and redundant description is omitted here.

[0279] For the operation for step 1135, refer to the description related to the operation (part or all) for step 1035 of FIG. 10, and redundant description is omitted here.

[0280] For the operation for step 1140, refer to the description related to the operation (part or all) for step 1040 of FIG. 10, and redundant description is omitted here.

[0281] For the operation for step 1145, refer to the description related to the operation (part or all) for step 1045 of FIG. 10, and redundant description is omitted here.

[0282] For the operation for step 1150, refer to the description related to the operation (part or all) for step 1050 of FIG. 10, and redundant description is omitted here.

[0283] For the operation for step 1155, refer to the description related to the operation (part or all) for step 1055 of FIG. 10, and redundant description is omitted here.

[0284] For the operation for step 1160, refer to the description related to the operation (part or all) for step 1060 of FIG. 10, and redundant description is omitted here.

[0285] In step 1165, the terminal may attempt a handover to the target cell (e.g., target cell 1) or target base station (e.g., target base station 1) using the target cell configuration information received in step 1140. To this end, the terminal may perform random access to the target cell and transmit an RRC Reconfiguration Complete message. If the terminal attempting to transmit the RRC Reconfiguration Complete message through random access satisfies at least one of the following conditions (conditions 1 to 11) (e.g., if the conditions listed in 1055 are not satisfied), the terminal may stop the ongoing handover or random access or RRC Reconfiguration Complete transmission and perform step 1170.

[0286] - Condition 1. When the predicted / derived HOF probability is greater than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0287] - Condition 2. When the predicted / derived RLF probability for the target cell is greater than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0288] - Condition 3. When the predicted / derived value (e.g., RSRP, RSRQ, SINR, TOS value) for the target cell is less than a specific threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0289] - Condition 4. If HOF is predicted when performing a handover.

[0290] - Condition 5. If RLF is expected when performing a handover to a specific cell (or if RLF is not expected when staying in the current cell).

[0291] - Condition 6. If a short TOS is expected when performing a handover to a specific cell (or a long TOS is expected when staying in the current cell), or if a handover ping-pong (e.g., between two cells, or between multiple cells) is expected.

[0292] - Condition 7. If an event (e.g. Event A1) is satisfied (implying that a handover is not required) based on the predicted cell measurement value (instead of the actual cell measurement value).

[0293] - Condition 8. If a (traditional or new) event (e.g. Event A1 or Event X' or RLF or HOF) is predicted or detected (e.g. based on measured / predicted values ​​or information) that implies that no handover is required.

[0294] - Condition 9. If the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the target (candidate) cell (or even if an offset value is added to this value) is less than the predicted value (e.g., RSRP, RSRQ, SINR, TOS value) for the source cell.

[0295] - Condition 10. If the predicted value for the target (candidate) cell (e.g., RLF probability) is greater than the predicted value for the source cell (e.g., RLF probability) (or even if an offset value is added to this value).

[0296] - Condition 11. If the probability of occurrence of a predicted / derived event (e.g., Event A3 or Event X') is less than a certain threshold (e.g., a threshold set by the base station in 710 or a fixed value defined in the standard).

[0297] At step 1170, the terminal may perform the RRE procedure (e.g., before T304 expiration, before T310 expiration, before T312 expiration, or before RLF detection). While performing the RRE procedure, the terminal may stop / terminate any running T304 timer.

[0298] In one embodiment of the present disclosure, the terminal can skip steps 1155 and 1160 and perform steps 1165 and 1170. That is, rather than performing RRE while receiving a handover instruction (1140) and performing a handover to a target cell, the terminal can perform RRE immediately after receiving a handover instruction (1140) (without a handover attempt or random access attempt procedure).

[0299] At step 1175, the terminal may receive an RRC Reestablishment Request from a new cell (e.g., target cell 2) or base station (e.g., target base station 2) as part of the RRE procedure. At this time, the terminal may indicate to the base station the reason for performing the RRE procedure or transmitting the RRC Reestablishment Request. The reason may be at least one of the following reasons (reasons 1 to 5).

[0300] - Reason 1. The predicted HOF probability for the handover instruction is high or HOF is predicted.

[0301] - Reason 2. The probability of RLF for the target cell predicted for the handover instruction is high or RLF is predicted.

[0302] - Reason 3. Low RSRP / RSRQ / SINR / TOS values ​​for the target cell predicted for the handover instruction.

[0303] - Reason 4. (Regarding handover instructions) Handover ping-pong is expected.

[0304] - Reason 5. An event (e.g., Event A1) that is set based on cell prediction / measurement values ​​(indicating that no handover is required) is satisfied.

[0305] At step 1180, the terminal may receive an RRC Reestablishment Complete message as part of the RRE procedure.

[0306] At step 1185, the new base station (e.g., target base station 2) may transmit a UE CONTEXT RELEASE (COMMAND) message to the source base station to notify the successful connection or RRE with the terminal. Target base station 2 may change the downlink data path and establish an NG interface by exchanging a PATH SWITCH REQUEST message (e.g., a message transmitted from the target base station to the AMF) and a PATH SWITCH REQUEST ACKNOWLEDGE message (e.g., a message transmitted from the AMF to target base station 2) with the AMF before transmitting the UE CONTEXT RELEASE (COMMAND) message.

[0307] At step 1190, the source base station may release the configuration information or context about the terminal after receiving the UE CONTEXT RELEASE (COMMAND) message from the target base station 2 (e.g., after a successful RRE). The source base station may stop Timer 3 for the corresponding cell after receiving the UE CONTEXT RELEASE (COMMAND) message from the target base station 2.

[0308] FIG. 12 is a diagram illustrating a procedure for performing prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0309] The operation for step 1205 refers to the description related to the operation (partial or entire) for step 705 of FIG. 7, and the redundant description is omitted here. Alternatively, the UE capability information message may include at least one of the following UE support capability information (information 1 to 2).

[0310] - Information 1. Whether the terminal supports the ability to accept and / or reject and / or postpone a handover instruction from the base station based on predictions (e.g., predictions for HOF and / or RLF and / or TOS and / or cell measurement values ​​and / or events) (using artificial intelligence)

[0311] - Information 2. Whether the terminal supports the ability to perform fast RRE during or before / after performing a handover instruction from the base station based on prediction (e.g., prediction of HOF and / or RLF and / or TOS and / or cell measurement values ​​and / or events) using artificial intelligence.

[0312] For the operation for step 1210, refer to the description related to the operation (part or all) for step 607 of FIG. 6, and redundant description is omitted here.

[0313] The operation for step 1215 refers to the description related to the operation (part or all) for step 610 of FIG. 6, and redundant description is omitted here.

[0314] At step 1220, the source base station may determine the target cell to which the terminal will be handed over. For example, this may be determined based on the cell measurement and / or prediction report transmitted by the terminal at step 1215.

[0315] For the operation for step 1225, refer to the description related to the operation (part or all) for step 1025 of FIG. 10, and redundant description is omitted here.

[0316] For the operation for step 1230, refer to the description related to the operation (part or all) for step 1030 of FIG. 10, and redundant description is omitted here.

[0317] For the operation for step 1235, refer to the description related to the operation (part or all) for step 1035 of FIG. 10, and redundant description is omitted here.

[0318] The operation for step 1240 refers to the description related to the operation (partial or entire) for step 1040 of FIG. 10, and redundant description is omitted here. The terminal may store the received target cell configuration information.

[0319] For the operation for step 1245, refer to the description related to the operation (part or all) for step 1045 of FIG. 10, and redundant description is omitted here.

[0320] For the operation for step 1250, refer to the description related to the operation (part or all) for step 1050 of FIG. 10, and redundant description is omitted here.

[0321] At step 1255, the terminal may perform step 1260 if at least one of the conditions described above at 1165 is satisfied.

[0322] At step 1260, the terminal may reject (or reject or ignore) a handover instruction to a target cell (e.g., target cell 1) or a target base station (e.g., target base station 1) received from the base station.

[0323] At step 1265, the terminal may stop the running timer T304.

[0324] In step 1270, the terminal may request the base station to reject the handover instruction to the target cell. For example, the terminal may transmit an instruction (e.g., within a Measurement report message, a UE Assistance information message, or a UE information response message) or a message (e.g., a Handover rejection request message) to the base station requesting rejection of the handover instruction. At this time, the terminal may indicate to the base station the reason for rejecting the handover instruction. The reason may be at least one of the reasons listed in 1175 described above. The terminal may report predicted / derived information to the base station. For example, the terminal may report the information listed in 715 (for the source cell, the target cell, or each neighboring cell) for reporting predicted information.

[0325] At step 1275, the source base station may stop running Timer 3.

[0326] At step 1280, the source base station may make a handover decision of the terminal to a new target cell (e.g., target cell 2) or target base station (e.g., target base station 2). This decision may be based on a cell measurement report (e.g., 1215) and / or a prediction report (e.g., 1270) received from the terminal.

[0327] For the operation for step 1285, refer to the description related to the operation (part or all) for step 1025 of FIG. 10, and redundant description is omitted here.

[0328] For the operation for step 1290, refer to the description related to the operation (part or all) for step 1030 of FIG. 10, and redundant description is omitted here.

[0329] For the operation for step 1295, refer to the description related to the operation (part or all) for step 1035 of FIG. 10, and redundant description is omitted here.

[0330] The operation for step 12100 refers to the description related to the operation (partial or entire) for step 1040 of FIG. 10, and redundant description is omitted here. The terminal may receive configuration information for a new target cell (e.g., target cell 2). The terminal receiving configuration information for a new target cell (e.g., target cell 2) may mean that the (source) base station permits / allows the terminal's request to reject a handover instruction (for target cell 1). Alternatively, the (source) base station may transmit an indicator (e.g., an indicator in a RRC Reconfiguration / RRC Resume / new RRC message) to the terminal, indicating that the terminal permits / allows the request to reject the handover instruction. In one embodiment of the present disclosure, the message used in step 12100 may be an RRC Reconfiguration / RRC Resume / new RRC message. Alternatively, the base station may transmit a message (e.g., a Handover reject accept message) permitting / allowing the terminal's request to reject the handover instruction.

[0331] In step 12105, the source base station may request the target cell 1 to cancel the handover (e.g., by sending a HANDOVER CANCEL message). This may be for the purpose of releasing the settings and resources allocated by the cell for the handover of the terminal without further maintenance. In one embodiment of the present disclosure, the source base station may perform the operation for step 12105 before or after step 12100.

[0332] For the operation for step 12110, refer to the description related to the operation (part or all) for step 1045 of FIG. 10, and redundant description is omitted here.

[0333] At step 12115, the terminal (which has received permission for the handover rejection request to target cell 1) may release the configuration information for target cell 1 received at 1240 without storing it any further.

[0334] The operation for step 12120 refers to the description related to the operation (part or all) for step 1050 of FIG. 10, and redundant description is omitted here.

[0335] For the operation for step 12125, refer to the description related to the operation (part or all) for step 1055 of FIG. 10, and redundant description is omitted here.

[0336] For the operation for step 12130, refer to the description related to the operation (part or all) for step 1060 of FIG. 10, and redundant description is omitted here.

[0337] The operation for step 12135 refers to the description related to the operation (part or all) for step 1065 of FIG. 10, and redundant description is omitted here.

[0338] For the operation for step 12140, refer to the description related to the operation (part or all) for step 1070 of FIG. 10, and redundant description is omitted here.

[0339] For the operation for step 12145, refer to the description related to the operation (part or all) for step 1075 of FIG. 10, and redundant description is omitted here.

[0340] For the operation for step 12150, refer to the description related to the operation (part or all) for step 1080 of FIG. 10, and redundant description is omitted here.

[0341] FIG. 13 is a diagram illustrating a procedure for performing prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0342] For the operations from step 1305 to step 1375, refer to the description of the operations (partial or entire) from step 1205 to step 1275 of FIG. 12, and any duplicate description is omitted here.

[0343] At step 1380, the source base station may or may not approve or disallow the terminal's request for rejection of the handover instruction. That is, the source base station may still want the terminal to follow the handover instruction to the target cell (e.g., the handover instruction transmitted by the base station to the terminal at step 1340). To this end, the source base station may first start running Timer 1. The source base station may start running Timer 1 because the terminal can perform the handover according to the base station's rejection without performing any more prediction.

[0344] In step 1385, the source base station may transmit to the terminal an indication (e.g., within an RRC Reconfiguration or RRC Resume message) or a message (e.g., a Handover rejection denial message) indicating that the terminal does not accept the request for rejection of the handover instruction. In one embodiment of the present disclosure, if the terminal receives a message (e.g., an RRC Reconfiguration message) from the base station that does not include configuration information for a new target cell, this may mean that the base station does not accept the terminal's request for rejection of the handover instruction.

[0345] At step 1390, the terminal may start driving T304 before performing the handover to the target cell (after receiving a disallowance for the handover rejection request).

[0346] In step 1395, the terminal may apply the target cell configuration information received and stored in step 1340 (for handover). The terminal may attempt a handover to the target cell using the target cell configuration information received in step 1340.

[0347] At step 13100, the terminal may perform random access to the target cell and transmit an RRC Reconfiguration Complete message.

[0348] For the operation for step 13105, refer to the description related to the operation (part or all) for step 632 of FIG. 6, and redundant description is omitted here.

[0349] The operation for step 13110 refers to the description related to the operation (part or all) for step 635 of FIG. 6, and redundant description is omitted here.

[0350] For the operation for step 13115, refer to the description related to the operation (part or all) for step 637 of FIG. 6, and redundant description is omitted here.

[0351] In one embodiment of the present disclosure, the terminal may start the operation of timer A when transmitting a handover rejection request (e.g., 1270 or 1370). The length of timer A may be information received at 1240. The terminal may stop or end the operation of timer A when the base station grants or denies the handover rejection request (e.g., 12100 or 1385). If the base station does not grant or deny the handover or timer A expires, the terminal may perform a RRE procedure, perform a handover to target cell 1, or remain connected to the current source cell.

[0352] FIG. 14 is a diagram illustrating a signaling procedure for performing prediction-based handover using artificial intelligence between a terminal and a base station according to one embodiment of the present disclosure.

[0353] For the operations from step 1405 to step 1450, refer to the description of the operations (partial or entire) from step 1305 to step 1350 of FIG. 13, and redundant descriptions are omitted here.

[0354] In step 1455, the terminal may perform step 1465 if at least one of the conditions described above related to step 1165 of FIG. 11 is satisfied. Alternatively, the terminal may perform step 1465 if at least one of the following conditions (conditions 1 to 6) is satisfied.

[0355] - Condition 1. When the terminal performs (current) handover, if any one of the conditions (conditions 1 to 11) described above related to step 1165 is satisfied.

[0356] - Condition 2. If the terminal postpones the handover (for a certain period of time (T)) and does not satisfy any of the conditions (conditions 1 to 11) mentioned above in relation to step 1165.

[0357] - Condition 3. If the predicted HOF probability is lower (by a certain offset value or more) when the handover is postponed (for a certain period of time (T)) compared to the predicted HOF probability when the terminal (currently) performs a handover.

[0358] - Condition 4. If the predicted RLF probability is lower (by a certain offset value or more) than the predicted RLF probability when the terminal performs the (current) handover and postpones the handover (for a certain period of time (T)).

[0359] - Condition 5. When the terminal performs a handover (currently), if the handover is postponed (for a certain period of time (T)) compared to the predicted TOS or RSRP or RSRQ or SINR value (for the target cell), and the predicted TOS or RSRP or RSRQ or SINR value is higher (than a certain offset value)

[0360] - Condition 6. If the probability of occurrence of the predicted event (e.g., Event A3) when the handover is postponed (for a certain period of time (T)) is higher (by a certain offset value or more) than the probability of occurrence of the predicted event (e.g., Event A3) when the terminal performs the (current) handover.

[0361] In one embodiment of the present disclosure, the offset value may be a fixed value in the standard or a variable value set by the base station to the terminal (e.g., at 1440).

[0362] At step 1465, the terminal may decide to postpone performing the handover. That is, the terminal may remain connected to the current source cell without performing the handover immediately.

[0363] In step 1470, the terminal may request the base station to postpone the handover instruction to the target cell. For example, the terminal may transmit an instruction (e.g., within a Measurement report message, a UE Assistance information message, or a UE information response message) or a message (e.g., a Handover postpone request message) to the base station requesting the postponement of the handover instruction. At this time, the terminal may indicate to the base station the reason for postponing the handover. The terminal may indicate at least one of the following reasons (reasons 1 to 10).

[0364] - Reason 1. (Currently) When handover is performed, the predicted HOF probability is high or HOF is predicted.

[0365] - Reason 2. (Currently) When handover is performed, the probability of RLF for the predicted target cell is high or RLF is predicted.

[0366] - Reason 3. (Currently) When handover is performed, the RSRP / RSRQ / SINR / TOS values ​​for the predicted target cell are low.

[0367] - Reason 4. (Currently) Handover ping-pong is expected when handover is performed.

[0368] - Reason 5. (Currently) When a handover is performed, an event (e.g., Event A1) set based on cell prediction / measurement values ​​(indicating that a handover is not required) is satisfied or the probability of occurrence increases.

[0369] - Reason 6. When the handover is postponed, the predicted HOF probability is low or HOF is not predicted.

[0370] - Reason 7. When handover is postponed, the predicted RLF probability for the target cell is low or RLF is not predicted.

[0371] - Reason 8. When handover is postponed, the predicted RSRP / RSRQ / SINR / TOS values ​​for the target cell are high.

[0372] - Reason 9. Handover ping-pong is not expected when handover is postponed.

[0373] - Reason 10. When a handover is postponed, the event (e.g., Event A3) set based on the cell prediction / measurement value (indicating that a handover is required) is satisfied or the probability of occurrence increases.

[0374] The terminal may report predicted / derived information to the base station. For example, the terminal may report the information described above in relation to step 715 of FIG. 7 (for the source cell, the target cell, or each neighboring cell) for reporting predicted information.

[0375] In one embodiment of the present disclosure, a terminal may report to a base station a (preferred) handover postponement time (T) or a point in time at which a postponed handover is to be performed. The time or point in time information may be a value derived by running an artificial intelligence model of the terminal.

[0376] At step 1475, the source base station may make a decision to allow the terminal's handover postponement request. The source base station may then stop or terminate the operation of Timer 3.

[0377] In step 1480, the source base station may transmit an indication (e.g., within an RRC Reconfiguration or RRC Resume message) or a message (e.g., a Handover postpone accept message) to the terminal indicating that it allows / permits the terminal's request to postpone the handover. The source base station may set a handover postponement time (T') or a time point at which the postponed handover is to be performed to the terminal.

[0378] In one embodiment of the present disclosure, the source base station may transmit an indication (e.g., within an RRC Reconfiguration or RRC Resume message) or a message (e.g., a Handover Postpone Accept message) to the terminal, indicating that it permits / accepts a handover postponement request, at the time of the postponed handover. The terminal and base station receiving this may perform the procedures after step 1490.

[0379] In one embodiment of the present disclosure, after the source base station makes a decision to reject the handover postponement request of the terminal at 1475, the source base station may transmit an indication (e.g., in an RRC Reconfiguration or RRC Resume message) or a message (e.g., a Handover postpone denial message) to the terminal at 1480, indicating that the handover postponement request of the terminal is rejected. After this, the terminal may not postpone the handover and may immediately perform a handover to the target cell (e.g., may perform operations after 1390 in FIG. 1m).

[0380] In step 1485, the terminal may stop or terminate the T304 timer and postpone the handover. The terminal may perform the handover after the handover postponement time (T') (e.g., 1487) set by the base station, or may perform the handover at the (postponed) handover time point set by the base station. Alternatively, the terminal may perform the handover after the handover postponement time (T) it has derived itself, or may perform the handover at the (postponed) handover time point it has derived itself.

[0381] At step 1490, the source base station may start running Timer 1 to coincide with the delayed handover timing.

[0382] At step 1495, the terminal may apply the target cell configuration information received and stored at step 1440 (for handover) in accordance with the delayed handover timing. The terminal may attempt a handover to the target cell using the target cell configuration information received at step 1440.

[0383] At step 14100, the terminal may start running the T304 timer.

[0384] In step 14105, the terminal may perform random access to the target cell and transmit an RRC Reconfiguration Complete message.

[0385] For the operation for step 14115, refer to the description related to the operation (part or all) for step 632 of FIG. 6, and redundant description is omitted here.

[0386] For the operation for step 14120, refer to the description related to the operation (part or all) for step 635 of FIG. 6, and redundant description is omitted here.

[0387] For the operation for step 14125, refer to the description related to the operation (part or all) for step 637 of FIG. 6, and redundant description is omitted here.

[0388] In one embodiment of the present disclosure, the terminal may start the operation of timer B when transmitting a handover postponement request (e.g., 1470). The length of timer B may be information received at 1440. The terminal may stop or end the operation of timer B when the base station grants or denies the handover postponement request (e.g., 1480). If the base station does not grant or deny the request or timer B expires, the terminal may perform an RRE procedure, perform a handover to target cell 1, or remain connected to the current source cell.

[0389] FIG. 15 is a diagram illustrating the structure of a terminal according to one embodiment of the present disclosure.

[0390] Referring to FIG. 15, a terminal according to one embodiment of the present disclosure may include an RF (Radio Frequency) processing unit (1510), a baseband processing unit (1520), a storage unit (1530), and a control unit (1540).

[0391] The RF processing unit (1510) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (1510) up-converts the baseband signal provided from the baseband processing unit (1520) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1510) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In FIG. 15, only one antenna is illustrated, but the terminal may be equipped with multiple antennas. In addition, the RF processing unit (1510) may include multiple RF chains. Furthermore, the RF processing unit (1510) may perform beamforming. For beamforming, the RF processing unit (1510) can adjust the phase and amplitude of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit can perform MIMO and receive multiple layers when performing MIMO operations.

[0392] The baseband processing unit (1520) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (1520) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (1520) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (1510). For example, in the case of an orthogonal frequency division multiplexing (OFDM) method, when transmitting data, the baseband processing unit (1520) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols by performing an inverse fast Fourier transform (IFFT) operation and inserting a cyclic prefix (CP). In addition, when receiving data, the baseband processing unit (1520) divides the baseband signal provided from the RF processing unit (1510) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform) operation, and then restores the received bit string through demodulation and decoding.

[0393] The baseband processing unit (1520) and the RF processing unit (1510) transmit and receive signals as described above. Accordingly, the baseband processing unit (1520) and the RF processing unit (1510) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (1520) and the RF processing unit (1510) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (1520) and the RF processing unit (1510) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. Additionally, different frequency bands may include super high frequency (SHF) (e.g., 2.NRHz, NRhz) bands, millimeter wave (mm wave) (e.g., 60GHz) bands.

[0394] The storage unit (1530) stores data such as basic programs, application programs, and setting information for the operation of the terminal according to one embodiment of the present disclosure. The storage unit (1530) provides the stored data upon request from the control unit (1540). The storage unit (1530) may be referred to as a memory.

[0395] The control unit (1540) controls the overall operations of the terminal. For example, the control unit (1540) transmits and receives signals through the baseband processing unit (1520) and the RF processing unit (1510). In addition, the control unit (1540) records and reads data in the storage unit (1530). For this purpose, the control unit (1540) may include at least one processor. For example, the control unit (1540) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs, and may include a multi-connection processing unit (1542) as illustrated in the drawing.

[0396] The processor (1540) may include various processing circuits and / or multiple processors. For example, the term “processor” as used herein, including in the claims, may include various processing circuits, including at least one processor. At least one processor, one or more processors may be configured to perform various functions described herein, individually and / or collectively, in a distributed fashion. As used herein, “processor,” “at least one processor,” and “one or more processors” may be configured to perform multiple functions. However, these terms encompass, without limitation, situations where one processor performs some of the functions and other processor(s) perform other parts of the functions, and situations where a single processor may perform all of the functions. Furthermore, the at least one processor may include a combination of processors that perform various of the disclosed functions in a distributed manner. The at least one processor may execute program instructions to achieve or perform various functions.

[0397] In one embodiment, at least one processor (1540) may be a general-purpose processor, such as a CPU, AP, or DSP (Digital Signal Processor), a graphics-only processor, such as a GPU or VPU (Vision Processing Unit), or an AI-only processor, such as an NPU. For example, if one or more processors are AI-only processors, the AI-only processors may be designed with a hardware structure specialized for processing a specific AI model.

[0398] The predefined operation rules or artificial intelligence model are characterized by being created through learning. Here, being created through learning means that a basic artificial intelligence model (or deep learning model) is trained using a plurality of learning data by a learning algorithm, thereby creating a predefined operation rule or artificial intelligence model set to perform a desired characteristic (or purpose). This learning may be performed on the device itself on which the artificial intelligence according to the present disclosure is performed, or may be performed through a separate server and / or system. Examples of the learning algorithm include, but are not limited to, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning.

[0399] An artificial intelligence model (or deep learning model) may be composed of multiple neural network layers. Each of the multiple neural network layers has multiple weight values, and performs neural network operations through operations between the operation results of the previous layer and the multiple weights. The multiple weights of the multiple neural network layers may be optimized based on the learning results of the artificial intelligence model. For example, the multiple weights may be updated so that the loss value or cost value obtained from the artificial intelligence model is reduced or minimized during the learning process. The artificial neural network may include a deep neural network (DNN), and examples thereof include, but are not limited to, a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), or deep Q-networks.

[0400] FIG. 16 is a diagram illustrating the structure of a base station according to one embodiment of the present disclosure.

[0401] Referring to FIG. 16, a base station according to an example of the present disclosure may include an RF processing unit (1610), a baseband processing unit (1620), a backhaul communication unit (1630), a storage unit (1640), and a control unit (1650).

[0402] The RF processing unit (1610) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (1610) up-converts the baseband signal provided from the baseband processing unit (1620) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1610) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In FIG. k, only one antenna is illustrated, but the base station may have multiple antennas. In addition, the RF processing unit (1610) may include multiple RF chains. Furthermore, the RF processing unit (1610) may perform beamforming. For beamforming, the RF processing unit (1610) may adjust the phase and magnitude of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit can perform downlink MIMO operations by transmitting one or more layers.

[0403] The baseband processing unit (1620) performs a conversion function between baseband signals and bit streams according to the physical layer specifications of the wireless access technology. For example, when transmitting data, the baseband processing unit (1620) generates complex symbols by encoding and modulating the transmission bit stream. In addition, when receiving data, the baseband processing unit (1620) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (1610). For example, in the case of OFDM, when transmitting data, the baseband processing unit (1620) generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (1620) divides the baseband signal provided from the RF processing unit (1610) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operation, and then restores the received bit string through demodulation and decoding. The baseband processing unit (1620) and the RF processing unit (1610) transmit and receive signals as described above. Accordingly, the baseband processing unit (1620) and the RF processing unit (1610) may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0404] The backhaul communication unit (1630) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (1630) converts a bit string transmitted from a base station to another node, such as an auxiliary base station or core network, into a physical signal, and converts a physical signal received from another node into a bit string.

[0405] The storage unit (1640) stores data such as basic programs, application programs, and configuration information for the operation of the base station. In particular, the storage unit (1640) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, and the like. Furthermore, the storage unit (1640) can store information that serves as a basis for determining whether to provide or terminate multiple connections to a terminal. Furthermore, the storage unit (1640) provides the stored data upon request from the control unit (1650). The storage unit (1640) may be referred to as a memory.

[0406] The control unit (1650) controls the overall operations of the base station. For example, the control unit (1650) transmits and receives signals through the baseband processing unit (1620) and the RF processing unit (1610) or through the backhaul communication unit (1630). In addition, the control unit (1650) records and reads data from the storage unit (1640). For this purpose, the control unit (1650) may include at least one processor and, as illustrated in the drawing, a multi-connection processing unit (1652).

[0407] The processor (1650) may include various processing circuits and / or multiple processors. For example, the term “processor” as used herein, including in the claims, may include various processing circuits, including at least one processor. One or more processors in at least one processor may be configured to perform various functions described herein, individually and / or collectively, in a distributed fashion. As used herein, “processor,” “at least one processor,” and “one or more processors” may be configured to perform various functions. However, these terms encompass, without limitation, situations where one processor performs some of the functions and other processor(s) perform other parts of the functions, and situations where a single processor may perform all of the functions. Furthermore, the at least one processor may include a combination of processors that perform various functions of the disclosed functions in a distributed manner. The at least one processor may execute program instructions to achieve or perform various functions.

[0408] In one embodiment, at least one processor (1y-50) may be a general-purpose processor, such as a CPU, AP, or DSP (Digital Signal Processor), a graphics-only processor, such as a GPU or VPU (Vision Processing Unit), or an AI-only processor, such as an NPU. For example, if one or more processors are AI-only processors, the AI-only processor may be designed with a hardware structure specialized for processing a specific AI model.

[0409] The predefined operation rules or artificial intelligence model are characterized by being created through learning. Here, being created through learning means that a basic artificial intelligence model (or deep learning model) is trained using a plurality of learning data by a learning algorithm, thereby creating a predefined operation rule or artificial intelligence model set to perform a desired characteristic (or purpose). This learning may be performed on the device itself on which the artificial intelligence according to the present disclosure is performed, or may be performed through a separate server and / or system. Examples of the learning algorithm include, but are not limited to, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning.

[0410] An artificial intelligence model (or machine learning or deep learning model) may be composed of multiple neural network layers. Each of the multiple neural network layers has multiple weight values, and performs neural network operations through operations between the operation results of the previous layer and the multiple weights. The multiple weights of the multiple neural network layers may be optimized based on the learning results of the artificial intelligence model. For example, the multiple weights may be updated so that the loss value or cost value obtained from the artificial intelligence model is reduced or minimized during the learning process. The artificial neural network may include a deep neural network (DNN), and examples thereof include, but are not limited to, a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), or deep Q-networks.

[0411] Meanwhile, the embodiments of the present disclosure disclosed in this disclosure and the drawings are merely specific examples presented to easily explain the technical content of the present disclosure and aid in understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art to which the present disclosure pertains that other modified examples based on the technical concepts of the present disclosure are possible.

[0412] Furthermore, the above embodiments may be combined and operated as needed. For example, parts of one embodiment of the present disclosure and parts of another embodiment may be combined to operate a base station and a terminal. Furthermore, the embodiments of the present disclosure are applicable to other communication systems, and other modifications based on the technical concepts of the embodiments may also be implemented. For example, the embodiments may be applied to LTE systems, 5G, NR systems, or 6G systems. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the following claims but also by equivalents thereof.

[0413] The specific examples used to illustrate embodiments according to the present disclosure are merely one combination of each criterion, method, detailed method, and operation. By combining at least two of the various techniques described, a terminal or base station can perform an AI-based handover operation in a next-generation mobile communication system. Furthermore, the handover operation may be performed according to a method determined through one or a combination of at least two of the aforementioned techniques. For example, it may be possible to perform a portion of the operation of one embodiment in combination with a portion of the operation of another embodiment.

[0414] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, a 'non-transitory storage medium' means only that it is a tangible device and does not contain signals (e.g., electromagnetic waves), and this term does not distinguish between cases where data is permanently stored in the storage medium and cases where it is temporarily stored. For example, a 'non-transitory storage medium' may include a buffer in which data is temporarily stored. In one embodiment, the method according to various embodiments disclosed in the present document may be provided as a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a device-readable storage medium (e.g., a compact disc read only memory (CD-ROM)), or may be distributed online (e.g., by download or upload) through an application 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 (e.g., a downloadable app) 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 an intermediary server.

Claims

1. In a method performed by a terminal of a wireless communication system, A step of transmitting a first message including capability information of the terminal associated with the artificial intelligence model to a base station for a serving cell; A step of receiving, from the base station, a second message including an instruction for a first handover to a first target cell and configuration information regarding the artificial intelligence model; A step of performing a prediction for the first handover using the artificial intelligence model based on the above setting information; and A method comprising the step of performing a first handover procedure for the first target cell if the above prediction is successful.

2. In paragraph 1, A method further comprising the step of performing an RRC (radio resource control) re-establishment procedure before the expiration of the timer for the first handover if the above prediction fails.

3. In paragraph 1, If the above prediction fails: A step of transmitting a third message to the base station for reporting the prediction; receiving a fourth message from the base station, the fourth message including an instruction for a second handover to a second target cell; and A method further comprising the step of performing a prediction for the second handover.

4. In paragraph 1, If the above prediction fails: A step of determining whether to postpone the first handover; A step of transmitting a fifth message to the base station for requesting postponement of the first handover; and Further comprising the step of receiving a sixth message including acceptance of the delay request from the base station, A method wherein the sixth message includes a delay time of the first handover.

5. In paragraph 1, The above capability information includes first information indicating whether the terminal can accept, reject, or postpone a handover instruction based on a prediction of the artificial intelligence model, or second information indicating whether the terminal can perform a fast RRE (RRC re-establishment) procedure based on a prediction of the artificial intelligence model. A method wherein the above configuration information includes at least one of a threshold of a handover failure probability, a threshold of a wireless connection failure probability, a threshold of a cell measurement value, or a threshold of a time of stay (TOS).

6. A method performed by a base station for a serving cell in a wireless communication system, A step of receiving a first message from a terminal, the first message including capability information of the terminal related to an artificial intelligence model; and A method comprising the step of transmitting, to the terminal, a second message including an instruction for a first handover to a first target cell and configuration information regarding the artificial intelligence model.

7. In paragraph 6, A step of receiving a third message including a prediction result for the first handover from the terminal; A method comprising the step of transmitting, to the terminal, a fourth message including an instruction for a second handover to a second target cell.

8. In paragraph 6, A step of receiving a fifth message for requesting postponement of the first handover from the terminal; and Further comprising the step of transmitting a sixth message including acceptance of the delay request to the terminal, A method wherein the sixth message includes a delay time of the first handover.

9. In the terminal of a wireless communication system, Transmitter and receiver; and Includes a control unit connected to the above transmitter and receiver, The above control unit: Transmitting a first message to a base station for a serving cell, the first message including capability information of the terminal associated with the artificial intelligence model, Receive from the base station a second message including an instruction for a first handover to a first target cell and configuration information regarding the artificial intelligence model, Predicting the first handover is performed using the artificial intelligence model based on the above setting information, and A terminal configured to perform a first handover procedure for the first target cell if the above prediction is successful.

10. In paragraph 9, the control unit, A terminal configured to perform an RRC (radio resource control) re-establishment procedure before the expiration of the timer for the first handover if the above prediction fails.

11. In paragraph 9, the control unit, If the above prediction fails: Transmitting a third message to the base station to report the prediction, Receive a fourth message from the base station including an instruction for a second handover to a second target cell, and A terminal configured to perform prediction for the second handover.

12. In paragraph 9, the control unit, If the above prediction fails: Decide on the postponement of the above first handover, Transmitting a fifth message to the base station for requesting a postponement of the first handover, and is configured to receive a sixth message from the base station, including acceptance of the delay request; The terminal, wherein the sixth message includes the delay time of the first handover.

13. In a base station of a wireless communication system, Transmitter and receiver; and Includes a control unit connected to the above transmitter and receiver, The above control unit: Receive a first message from a terminal, including capability information of the terminal associated with an artificial intelligence model, and A base station configured to transmit, to the terminal, a second message including an instruction for a first handover to the first target cell and configuration information regarding the artificial intelligence model.

14. In the 13th paragraph, the control unit, Receive a third message including a prediction result for the first handover from the terminal, A base station configured to transmit, to the terminal, a fourth message including an instruction for a second handover to a second target cell.

15. In the 13th paragraph, the control unit, Receive a fifth message for requesting postponement of the first handover from the terminal, and is set to transmit a sixth message including acceptance of the delay request to the terminal; The base station, wherein the sixth message includes the delay time of the first handover.

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