Method and apparatus for supporting conditional LTM operation in wireless communication system

Abstract

An operation of a wireless user device comprises acquiring LTM configuration information from a source cell on the basis of conditional LTM, wherein: the LTM configuration information comprises information about one or more candidate cells and event condition information for performing LTM; the wireless user device performs uplink / downlink pre-synchronization with the one or more candidate cells; and the wireless user device performs measurement by acquiring a reference signal from the one or more candidate cells, checks whether an event condition is satisfied on the basis of a result of the measurement, and completes an LTM procedure by transmitting an RRC reconfiguration message to a target cell satisfying the event condition, from among the one or more candidate cells, wherein the wireless user device may complete the LTM procedure by transmitting the RRC reconfiguration message to the target cell via a TAC for each of the one or more candidate cells acquired from the source cell.

Description

Method and device for supporting conditional LTM operation in a wireless communication system

[0001] The present invention relates to a method and apparatus for supporting a conditional LTM (L1 / L2 layer triggered mobility) operation in a wireless communication system. Specifically, the invention relates to a method and apparatus for a terminal to receive timing advance command (TAC) information of one or more candidate cells from a source cell during a conditional LTM operation.

[0002]

[0003] The International Telecommunication Union (ITU) is developing the International Mobile Telecommunication (IMT) framework and standards, and recently, discussions for 5th generation (5G) communication are underway through a program called "IMT for 2020 and beyond."

[0004] In order to meet the requirements presented in "IMT for 2020 and beyond," discussions are underway to support various numerologies for time-frequency resource unit standards in 3GPP (3rd Generation Partnership Project) NR (New Radio) systems, taking into account various scenarios, service requirements, and potential system compatibility.

[0005] Mobility support measures may be necessary in wireless communication systems, and the following describes measures for this purpose.

[0006]

[0007] The present invention can provide a method and apparatus that support conditional LTM operation in a wireless communication system.

[0008] The present invention may provide a method and apparatus for a terminal to receive TAC information of one or more candidate cells from a source cell in a conditional LTM operation.

[0009] The present invention can provide a method and apparatus for checking TAT (time alignment timer) information when a terminal receives TACs of one or more candidate cells in a conditional LTM operation.

[0010] The present invention can provide a method and apparatus for checking the validity of a configured grant (CG) occasion of a target cell in a conditional LTM operation.

[0011]

[0012] According to one embodiment, in a wireless user device, a wireless transceiver, one or more processors, and a memory that stores instructions for the wireless device when executed by one or more processes, the operation of the wireless device comprises: obtaining LTM configuration information based on conditional LTM (L1 / L2 layer triggered mobility) from a source cell, wherein the LTM configuration information includes information on one or more candidate cells and event condition information for performing LTM, the wireless user device performs uplink / downlink pre-synchronization with one or more candidate cells, the wireless user device obtains a reference signal from one or more candidate cells and performs a measurement, checks whether the event condition is satisfied based on the measurement result, and completes the LTM procedure by transmitting a radio resource control (RRC) reconstruction message to a target cell among one or more candidate cells that satisfies the event condition, wherein the wireless user device can complete the LTM procedure by transmitting an RRC reconstruction message to the target cell through a timing advance command (TAC) for each of the one or more candidate cells obtained from the source cell.

[0013] Additionally, according to one embodiment, a method of operation of a wireless user device comprises the steps of: obtaining LTM configuration information based on conditional LTM from a source cell, wherein the LTM configuration information includes information about one or more candidate cells and event condition information for performing LTM; performing uplink / downlink pre-synchronization with one or more candidate cells; the wireless user device obtaining a reference signal from one or more candidate cells and performing a measurement, and verifying whether the event condition is satisfied based on the measurement result; and transmitting an RRC reconstruction message to a target cell among one or more candidate cells that satisfies the event condition to complete the LTM procedure, wherein the wireless user device may complete the LTM procedure by transmitting an RRC reconstruction message to the target cell through the TAC for each of the one or more candidate cells obtained from the source cell.

[0014] In addition, the following points may apply in common.

[0015] According to one embodiment, a wireless user device receives a PDCCH order for each of one or more candidate cells from a source cell and then transmits a preamble to each of one or more candidate cells, wherein the source cell obtains a TAC from each of one or more candidate cells based on the preamble transmitted to each of one or more candidate cells by the wireless user device, and the wireless user device can obtain an LTM TAC MAC CE (medium access control control element) containing the TAC for each of one or more candidate cells from the source cell.

[0016] Additionally, according to one embodiment, a wireless user device receives one or more TATs from a source cell via RRC signaling, and the LTM TAC MAC CE may further include a TAT for a TAC for each of one or more candidate cells.

[0017] Additionally, according to one embodiment, a wireless user device has a configured grant (CG) for a conditional LTM and a CG occasion based on the CG, wherein the CG occasion is associated with at least one reference signal, and the wireless user device receives the reference signal from one or more candidate cells to perform a measurement, checks whether an event condition is satisfied based on the measurement, and checks whether the CG occasion is valid based on whether the event condition is satisfied.

[0018] In addition, according to one embodiment, the wireless user device can complete the LTM procedure by transmitting an RRC reconstruction message through the first arriving CG occupation among the CG occupations associated with the reference signal satisfying the event condition.

[0019] Additionally, according to one embodiment, the wireless user device transmits a measurement report for one or more candidate cells to a source cell based on at least one of periodic and event-based reporting, and receives conditional LTM information and one or more TCI status information related to the candidate cells from the source cell, wherein the TCI status information related to the one or more candidate cells may include a list of TCI status IDs for each of the candidate cells or a current TCI status ID.

[0020]

[0021] According to the present disclosure, there is an effect of providing a method to support conditional LTM operation in a wireless communication system.

[0022] According to the present disclosure, there is an effect of providing a method in which a terminal receives TAC information of one or more candidate cells from a source cell in a conditional LTM operation.

[0023] According to the present disclosure, there is an effect of providing a method for checking TAT information when a terminal receives TACs of one or more candidate cells in a conditional LTM operation.

[0024] According to the present disclosure, there is an effect of providing a method to check whether the CG occupancy of a target cell is valid in a conditional LTM operation.

[0025]

[0026] FIG. 1 is a drawing for illustrating an NR frame structure to which the present disclosure can be applied.

[0027] FIG. 2 is a diagram showing an NR resource structure to which the present disclosure can be applied.

[0028] FIG. 3 is a diagram showing cell-level mobility and beam-level mobility applicable to the present disclosure.

[0029] FIG. 4 is a diagram showing an LTM scenario applicable to the present disclosure.

[0030] FIG. 5 is a diagram showing signaling and setting information in the LTM preparation stage applicable to the present disclosure.

[0031] FIG. 6 is a diagram illustrating the signaling and setting procedure for an initial synchronization step applicable to the present disclosure.

[0032] FIG. 7 is a diagram illustrating a method by which a terminal applicable to the present disclosure performs uplink synchronization.

[0033] FIG. 8 is a diagram showing signaling for an LTM cell change execution procedure applicable to the present disclosure.

[0034] FIG. 9 is a drawing showing a cell change MAC CE applicable to the present disclosure.

[0035] FIG. 10 is a diagram showing the signaling of the LTM cell change completion step applicable to the present disclosure.

[0036] FIG. 11 is a diagram illustrating an inter-base station handover procedure applicable to the present disclosure.

[0037] FIG. 12 is a diagram illustrating a procedure for performing an intra-AMF / UPF conditional handover applicable to the present disclosure.

[0038] FIG. 13 is a diagram showing a cell switch command MAC CE applicable to the present disclosure.

[0039] FIG. 14 is a diagram showing a candidate cell TCI state activation / deactivation MAC CE applicable to the present disclosure.

[0040] FIG. 15 is a diagram illustrating a conditional LTM operation applicable to the present disclosure.

[0041] FIG. 16 is a diagram illustrating a method in which an LTM TAC MAC CE is transmitted to a terminal based on a conditional LTM applicable to the present disclosure.

[0042] FIG. 17 is a drawing showing an LTM TAC MAC CE applicable to the present disclosure.

[0043] FIG. 18 is a diagram showing the LTM TAC MAC CE format when a plurality of TAT RRC parameters applicable to the present disclosure are set as terminals.

[0044] FIG. 19 is a diagram showing the relationship between SSB and CG occupations applicable to the present disclosure.

[0045] FIG. 20 is a diagram illustrating a RACH-less conditional handover procedure applicable to the present disclosure.

[0046] FIG. 21 is a diagram illustrating a RACH-less conditional handover procedure applicable to the present disclosure.

[0047] FIG. 22 is a diagram showing a case where TCI state IDs corresponding to beams possible in candidate cells applicable to the present disclosure are indicated to each candidate cell.

[0048] FIG. 23 is a diagram showing a case where TCI state IDs corresponding to beams possible in candidate cells applicable to the present disclosure are indicated to each candidate cell.

[0049] FIG. 24 is a diagram showing a MAC CE for indicating the TCI status for one or more candidate cells applicable to the present disclosure.

[0050] FIG. 25 is a diagram showing the operation of a wireless user device applicable to the present disclosure.

[0051] FIG. 26 is a drawing showing a device configuration applicable to the present disclosure.

[0052]

[0053] Hereinafter, embodiments of the present disclosure are described in detail with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein.

[0054] In describing the embodiments of the present disclosure, if it is determined that a detailed description of known configurations or functions may obscure the essence of the present disclosure, such detailed description is omitted. Furthermore, parts of the drawings unrelated to the description of the present disclosure have been omitted, and similar parts are denoted by similar reference numerals.

[0055] In the present disclosure, when a component is described as being "connected," "combined," or "joined" with another component, this may include not only a direct connection but also an indirect connection in which another component exists in between. Furthermore, when a component is described as "comprising" or "having" another component, this means that, unless specifically stated otherwise, it does not exclude the other component but may include an additional component.

[0056] In the present disclosure, terms such as first, second, etc. are used solely for the purpose of distinguishing one component from another and do not limit the order or importance of the components unless specifically stated otherwise. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and likewise, a second component in one embodiment may be referred to as a first component in another embodiment.

[0057] In this disclosure, distinct components are intended to clearly describe their respective features and do not imply that the components are separate. That is, multiple components may be integrated to form a single hardware or software unit, or a single component may be distributed to form multiple hardware or software units. Accordingly, such integrated or distributed embodiments are included within the scope of this disclosure, unless otherwise noted.

[0058] In the present disclosure, the components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, embodiments consisting of a subset of the components described in one embodiment are also included within the scope of the present disclosure. Furthermore, embodiments including additional components in addition to the components described in various embodiments are also included within the scope of the present disclosure.

[0059] The present disclosure describes a wireless communication network, and operations performed in the wireless communication network may be performed in the process of controlling the network and transmitting or receiving signals by a system (e.g., a base station) governing the wireless communication network, or in the process of transmitting or receiving signals by a terminal connected to the wireless network.

[0060] It is self-evident that various operations performed for communication with a terminal in a network consisting of multiple network nodes, including a base station, can be performed by the base station or other network nodes other than the base station. The term 'Base Station (BS)' may be replaced by terms such as fixed station, Node B, eNodeB (eNB), ng-eNB, gNodeB (gNB), and Access Point (AP). Additionally, the term 'terminal' may be replaced by terms such as User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS), Subscriber Station (SS), and non-AP Station (non-AP STA).

[0061] In the present disclosure, transmitting or receiving a channel includes the meaning of transmitting or receiving information or signals through said channel. For example, transmitting a control channel means transmitting control information or signals through the control channel. Similarly, transmitting a data channel means transmitting data information or signals through the data channel.

[0062] In the following description, the term NR (New Radio) system is used for the purpose of distinguishing the system to which various examples of the present disclosure are applied from existing systems, but the scope of the present disclosure is not limited by this term.

[0063] NR systems support various subcarrier spacing (SCS) while considering diverse scenarios, service requirements, and potential system compatibility. Furthermore, NR systems can support the transmission of physical signals / channels through multiple beams to overcome poor channel environments, such as high path loss, phase noise, and frequency offset occurring at high carrier frequencies. Through this, NR systems can support applications such as enhanced mobile broadband (eMBB), massive machine type communications (mMTC) / ultra machine type communications (uMTC), and ultra reliable and low latency communications (URLC).

[0064] Hereinafter, 5G mobile communication technology can be defined to include not only NR systems but also existing LTE-A (Long Term Evolution-Advanced) systems and LTE (Long Term Evolution) systems. 5G mobile communication may include not only newly defined NR systems but also technologies that operate considering backward compatibility with previous systems. Accordingly, the 5G mobile communication described below may include technologies that operate based on NR systems and technologies that operate based on previous systems (e.g., LTE-A, LTE), and is not limited to specific systems.

[0065] First, I would like to briefly explain the physical resource structure of the wireless communication system to which the present invention is applied.

[0066] FIG. 1 is a drawing for illustrating an NR frame structure to which the present disclosure can be applied.

[0067] In NR, the basic unit of the time domain is It could be, and N can be 4096. Meanwhile, the basic unit of the time domain in LTE is It could be, And, = can be 2048. The constant for the multiple relationship between the NR time base unit and the LTE time base unit is k= It can be defined as.

[0068] Referring to FIG. 1, the time structure of a frame for downlink / uplink (DL / UL) transmission is It can have. Here, one frame is It consists of 10 subframes corresponding to time. The number of consecutive OFDM symbols per subframe is = It may be possible. In addition, each frame may be divided into two half frames of the same size, half frame 1 may consist of subframes 0-4, and half frame 2 may consist of subframes 5-9.

[0069] represents the timing advance (TA) between the downlink (DL) and uplink (UL). Here, the transmission timing of the uplink transmission frame i is determined based on the downlink reception timing at the terminal and the following Equation 1.

[0070] [Mathematical Formula 1]

[0071]

[0072]

[0073] Here, can be a TA offset value resulting from duplex mode differences, etc. In FDD (Frequency Division Duplex), Although it has a value of 0, in TDD (Time Division Duplex), considering the margin for DL-UL switching time, It can be defined as a fixed value. For example, in TDD (Time Division Duplex) of FR1 (Frequency Range 1), which is a frequency below 6 GHz. is 39936 or 25600 It could be. 39936 is 20.327μs, and 25600 is 13.030 μs. Also, at FR2 (Frequency Range 2), which is a millimeter wave (mmWave) frequency is 13792 It could be. In this case, 13792 It is 7.020 μs.

[0074] FIG. 2 is a diagram showing an NR resource structure to which the present disclosure can be applied.

[0075] Resource elements (REs) within a resource grid can be indexed according to each subcarrier spacing. Here, one resource grid can be created for each antenna port and for each subcarrier spacing. Uplink and downlink transmission and reception can be performed based on the corresponding resource grid.

[0076] In the frequency domain, a single Resource Block (RB) consists of 12 REs, and an index (nPRB) for one RB can be configured for each of the 12 REs. The index for an RB can be utilized within a specific frequency band or system bandwidth. The index for an RB can be defined as shown in Equation 2 below. Here, represents the number of subcarriers per RB, and k represents the subcarrier index.

[0077] [Mathematical Formula 2]

[0078]

[0079]

[0080] Various numerals can be configured to satisfy the various services and requirements of an NR system. For example, while an LTE / LTE-A system may support one subcarrier spacing (SCS), an NR system may support multiple SCSs.

[0081] A new numerology for an NR system that supports multiple SCSs can operate in frequency ranges or carriers such as 3 GHz or lower, 3 GHz-6 GHz, 6 GHz-52.6 GHz, or 52.6 GHz or higher to solve the problem that wide bandwidth could not be used in frequency ranges or carriers such as 700 MHz or 2 GHz.

[0082] Table 1 below shows examples of numerals supported by the NR system.

[0083] [Table 1]

[0084]

[0085]

[0086] Referring to Table 1 above, the numeral can be defined based on the subcarrier spacing (SCS), cyclic prefix (CP) length, and the number of OFDM symbols per slot used in the Orthogonal Frequency Division Multiplexing (OFDM) system. These values ​​can be provided to the terminal through the upper layer parameters DL-BWP-mu and DL-BWP-cp for the downlink, and through the upper layer parameters UL-BWP-mu and UL-BWP-cp for the uplink.

[0087] In Table 1 above, when the subcarrier spacing setting index (u) is 2, the subcarrier spacing (Δf) is 60 kHz, and normal CP and extended CP may be applied. For other numerals indexes, only normal CP may be applied.

[0088] A normal slot can be defined as the basic time unit used to transmit a single piece of data and control information in an NR system. The length of a normal slot can be set to the number of 14 OFDM symbols by default. In addition, unlike a slot, a subframe has an absolute time length of 1 ms in an NR system and can be used as a reference time for the length of other time intervals. Here, for the coexistence or backward compatibility of LTE systems and NR systems, time intervals similar to LTE subframes may be required in NR specifications.

[0089] For example, in LTE, data can be transmitted based on a unit of time called a Transmission Time Interval (TTI), and the TTI can be set in units of one or more subframes. Here, one subframe can be set to 1ms and can contain 14 OFDM symbols (or 12 OFDM symbols).

[0090] Additionally, non-slots may be defined in NR. A non-slot may refer to a slot having a number of symbols smaller than that of a normal slot by at least one symbol. For example, when providing low latency, such as in URLLC services, latency can be reduced through non-slots having a number of symbols smaller than that of a normal slot. Here, the number of OFDM symbols included in the non-slot may be determined by considering the frequency range. For example, in a frequency range of 6 GHz or higher, a non-slot with a length of 1 OFDM symbol may be considered. As an additional example, the number of OFDM symbols defining the non-slot may include at least 2 OFDM symbols. Here, the range of the number of OFDM symbols included in the non-slot may be set as the length of a mini-slot up to a predetermined length (e.g., normal slot length - 1). However, as a specification for the non-slot, the number of OFDM symbols may be limited to a range of 2, 4, or 7 symbols, but is not limited thereto.

[0091] In addition, for example, in the unlicensed band below 6 GHz, subcarrier spacing corresponding to u 1 and 2 may be used, and in the unlicensed band above 6 GHz, subcarrier spacing corresponding to u 3 and 4 may be used. For example, when u is 4, it may be used for the Synchronization Signal Block (SSB).

[0092] [Table 2]

[0093]

[0094]

[0095] Table 2 shows the number of OFDM symbols per slot for normal CP by subcarrier spacing setting (u) ( ), number of slots per frame( ), number of slots per subframe( ) represents. Table 2 shows the values ​​described above based on a normal slot with 14 OFDM symbols.

[0096] [Table 3]

[0097]

[0098]

[0099] Table 3 shows the number of slots per frame and the number of slots per subframe based on a normal slot with 12 OFDM symbols per slot when extended CP is applied (i.e., when u is 2 and subcarrier spacing is 60 kHz).

[0100] As mentioned above, one subframe may correspond to 1ms on the time axis. Additionally, one slot may correspond to 14 symbols on the time axis. For example, one slot may correspond to 7 symbols on the time axis. Accordingly, the number of slots and symbols to be considered within 10ms corresponding to one radio frame may be set differently. Table 4 may show the number of slots and symbols according to each SCS. In Table 4, an SCS of 480kHz may not be considered, but is not limited to these examples.

[0101] [Table 4]

[0102]

[0103]

[0104] In a wireless communication system, a terminal can perform mobility-based operations. The terminal can change the serving cell (e.g., PCell / PSCell) based on mobility. For example, if the terminal detects a serving cell with better quality than the currently connected serving cell, it can change to the cell with better quality, thereby enabling efficient communication. Here, the terminal can perform measurements based on legacy mobility and report the measurement information to the network. Based on the terminal report, the network can determine whether a serving cell with better quality exists than the currently connected serving cell and perform a change to the serving cell with better quality.

[0105] For example, legacy mobility can be a Layer 3-based mobility operation based on L3 mobility. Specifically, the terminal performs measurements based on Layer 3-based signaling, transmits the measurement report to the network, and then changes the serving cell based on network instructions. That is, the terminal and the network can perform measurements based on RRC (radio resource signal) signaling to change the serving cell. When the terminal changes the serving cell based on L3 mobility, the terminal can connect to the new serving cell after resetting the RRC / PDCP (packet data convergence protocol) and resetting the MAC (medium access control) / PHY layer. In other words, while the terminal can reconfigure each layer when changing the serving cell based on mobility, performing this operation every time the terminal changes the serving cell can lead to problems such as prolonged latency and downtime, and increased overhead.

[0106] FIG. 3 is a diagram illustrating cell-level mobility and beam-level mobility applicable to the present disclosure. Referring to FIG. 3(a), the mobility of a terminal can be controlled at the cell level. Cell-level mobility can be configured and operated based on RRC signaling and may be a mobility control operation within a base station (e.g., intra gNB) or between base stations (e.g., inter gNB). That is, when a terminal changes the serving cell based on cell-level mobility, the terminal can perform a procedure to perform a handover to a new serving cell based on RRC signaling.

[0107] Referring to FIG. 3(b), the mobility of the terminal can be controlled at the beam level. Beam-level mobility may be an operation that controls the mobility of the terminal on a beam-by-beam basis. For example, the terminal may perform a beam-level mobility operation when controlling mobility to different cells within the same base station (e.g., intra gNB). As another example, the terminal may perform a beam-level mobility operation for inter-cell beam management (ICBM) as beam management between the same base stations. Here, beam-level mobility may be supported without RRC signaling, but is not limited thereto.

[0108] Considering the long latency and downtime and significant overhead mentioned above, LTM (L1 / L2 layer triggered mobility) operation may be considered. LTM may be a method of controlling mobility based on lower layers (L1 / L2) to support terminal mobility faster than the L3 mobility mentioned above. In LTM operation, when the base station receives the terminal's L1 measurement result, it can transmit an LTM cell switch command MAC CE (control element) (LTE cell switch command MAC CE) to the terminal instructing a cell change. That is, unlike L3 mobility, LTM is not performed based on RRC signaling but supports lower-layer-based mobility, thereby reducing latency and downtime and decreasing overhead. Specifically, the terminal transmits the L1 measurement result to the network, and the network can provide L2 signaling instructing LTM operation to the terminal, and LTM operation can be performed based on this.

[0109] FIG. 4 is a diagram illustrating an LTM scenario applicable to the present disclosure. Referring to FIG. 4(a), a terminal (410) can perform an LTM operation when moving to different distributed units (DU) within the same central unit (CU). That is, the terminal (410) can move to a different DU within the same CU by transmitting an L1 measurement report to a base station and receiving an LTM cell switch command MAC CE from the base station.

[0110] Referring to FIG. 4(b), the terminal (410) can perform an LTM operation when changing the serving cell within the same DU. The terminal (410) can change the serving cell within the same DU by transmitting an L1 measurement report to the base station and receiving an LTM cell switch command MAC CE from the base station. Additionally, referring to FIG. 4(c), the terminal (410) can perform an LTM operation when moving to a different CU. That is, the terminal (410) can move to a different CU by transmitting an L1 measurement report to the base station and receiving an LTM cell switch command MAC CE from the base station.

[0111] When performing an LTM operation, the network can determine a target cell among candidate LTM cells based on an L1 measurement report and transmit a MAC CE to the terminal (410) instructing it to change to the target cell.

[0112]

[0113] For example, an intra-CU LTM procedure may be performed within the same CU. An intra-CU LTM procedure may be divided into LTM preparation, early sync, LTM cell switch execution, and LTM cell switch completion, but is not limited thereto.

[0114] FIG. 5 is a diagram showing signaling and setting information in the LTM preparation stage applicable to the present disclosure. Referring to FIG. 5, a terminal (510) can transmit a measurement report including signal strength information of serving cells and adjacent cells to a base station (520). For example, for convenience of explanation, the following description uses a gNB as the base station, but is not limited thereto and can be applied in the same way to a base station of another wireless system.

[0115] For example, the measurement report transmitted by the terminal (510) to the base station (520) during the LTM preparation phase may be an L3 measurement report. The base station (520) may determine one or more LTM candidate cells based on the measurement report and set one or more LTM candidate cell configuration information to the terminal (510) through an RRC message (e.g., RRC reconfiguration). The terminal (510) may receive an RRC message containing LTM candidate cell configuration information, set up an LTM candidate cell based thereon, and then transmit an RRC message (e.g., RRC reconfiguration complete) to the base station (520) to complete the LTM candidate cell configuration. Specifically, the LTM configuration may include the information in Table 5 below. However, the LTM configuration may include additional information and may not be limited to Table 5 below. In Table 5, the reference configuration may be RRC configuration information that applies commonly to all candidate cells, and the candidate to release list may include information on LTM candidate cells that need to be released based on the LTM candidate ID. Additionally, the candidate to addition & modification list may be a list of LTM candidate cells that need to be newly added or modified. That is, the LTM configuration information provided by the network to the terminal may include information on LTM candidate cells to be released and information on LTM candidate cells to be added or modified.

[0116] Additionally, the serving cell no reset ID may be an identifier with an integer value from 1 to 9 that indicates whether the terminal has a radio link control (RLC) layer information change and a PDCP data recovery trigger. The CSI resource config to addition & modification list may be CSI resource information that is newly added or modified, and the CSI resource config to release list may be CSI resource information that must be released.

[0117] Additionally, the attempt LTM switch may be a configuration that causes the terminal to perform an LTM cell switch to that cell when the terminal searches for a suitable cell and the cell selected by the terminal is an LTM candidate cell, and the corresponding parameter is configured in the candidate cell information. The serving cell UE measured TA ID may be an identifier used to determine whether the terminal performs a terminal-based TA (timing advance) measurement. That is, Table 5 may include information related to LTM settings, but is not limited thereto.

[0118] [Table 5]

[0119]

[0120]

[0121] Additionally, within the configuration for one or more LTM candidate cells, the information for a single LTM candidate cell may be as shown in Table 6. Specifically, the candidate ID is the identifier of the LTM candidate cell, the candidate PCI is the physical cell identifier of the candidate cell, and the synchronization signal block (SSB) configuration may include the SSB configuration information of the LTM candidate cell, and may include frequency information (ARFCN), subcarrier interval, period, burst position, and physical broadcast channel (PBCH) power information. Additionally, the candidate configuration may be RRC configuration information for the LTM candidate cell, and config complete may indicate whether the candidate configuration is the complete RRC information of the candidate cell. Additionally, the early UL sync config may be configuration information for performing early uplink synchronization. Initial uplink synchronization configuration information may include at least one of uplink frequency, RACH (random access channel) configuration, BWP (bandwidth part), number of RACH occasions, PRACH root sequence index, PRACH subcarrier interval, and timing advance offset information. Additionally, the SUL (supplemental uplink) initial uplink synchronization configuration (early UL sync config SUL) may include SUL configuration information for initial uplink synchronization.Additionally, the transmission configuration indicator (TCI) information may include TCI information, and the no reset ID may include a unique identifier of an LTM candidate cell that enables the terminal to determine whether to change RLC layer information and trigger PDCP data recovery. The terminal measured TA ID (UE measured TA ID) may be an identifier used to determine whether the terminal will perform terminal-based TA measurement, but is not limited thereto.

[0122] [Table 6]

[0123]

[0124]

[0125] FIG. 6 is a diagram illustrating a signaling and setup procedure for an initial synchronization step applicable to the present disclosure. Referring to FIG. 6, when a terminal (610) receives setup information for an LTM candidate cell, it can perform downlink and uplink synchronization for the candidate cell in advance before performing LTM. That is, the terminal (610) can perform early synchronization after LTM preparation. By performing synchronization in advance through early synchronization, the terminal (610) can reduce the delay time that occurs when moving to the candidate cell.

[0126] Specifically, the terminal (610) can perform downlink synchronization based on SSB information included in LTM candidate cell information (LTM candidate). Additionally, the terminal (610) can receive a PDCCH (physical downlink control channel) instructing the LTM candidate cell to perform RACH from the serving cell, and can perform uplink synchronization through RACH based thereon.

[0127] Specifically, FIG. 7 is a diagram illustrating a method by which a terminal applicable to the present disclosure performs uplink synchronization. Referring to FIG. 7, the terminal (710) can determine whether the TA ID (ltm-UE-MeasuredTA-ID) of the LTM candidate cell is the same as the TA ID (ltm-ServingCellUE-MeasuredTA-ID) of the current serving cell. If the TA ID of the LTM candidate cell and the TA ID of the current serving cell are the same, the terminal (710) can perform TA measurement and may not perform initial uplink synchronization. On the other hand, if the TA ID of the candidate cell is different from the TA ID of the current serving cell, the terminal (710) can receive a PDCCH from the serving cell instructing the base station (720) to perform RACH to the LTM candidate cell and can transmit a RACH preamble to the LTM candidate cell. However, the terminal (710) may not receive a random access response (RAR) after transmitting a RACH preamble, unlike the existing RACH procedure. Therefore, the terminal (710) may not perform monitoring for receiving a RAR from an LTM candidate cell, and thus may not interfere with the scheduling of the serving cell. For example, in the existing RACH procedure, TA information may be included in the RAR, and the terminal (710) may obtain TA information through the RAR. Since the terminal (710) does not receive a RAR from an LTM candidate cell, the TA information may be included in a cell switch command MAC CE that instructs LTM execution later, and this will be described later.

[0128] FIG. 8 is a diagram illustrating signaling for an LTM cell change execution procedure applicable to the present disclosure. Referring to FIG. 8, a terminal (810) may receive a plurality of LTM candidate cells (830, 840) based on the above description. For example, the terminal (810) may receive a reference signal (RS) from one or more of the received LTM candidate cells (830, 840) and measure the signal strength thereof. Afterward, the terminal (810) may report an L1 measurement result (L1 measurement report) to a source cell (820). The network may determine whether to switch LTM cells based on the L1 measurement result obtained from the terminal (810) and may transmit a MAC CE to the terminal (810) instructing a cell change to a specific LTM candidate cell among the received LTM candidate cells (830, 840). That is, the terminal (810) may receive a cell switch command MAC CE. When the terminal (810) receives a cell switch command MAC CE (or cell switch command MAC CE), the terminal (810) may determine whether it has a valid TA for the cell. If the terminal (810) has a valid TA for the cell, the terminal (810) may not perform a RACH procedure based on a dynamic grant / configured grant (DG / CG). That is, the terminal (810) may perform a RACH-less operation. On the other hand, if the terminal (810) does not have a valid TA for the cell, the terminal (810) may perform a RACH procedure for the cell.

[0129] For example, FIG. 9 illustrates a cell switch command MAC CE applicable to the present disclosure. However, FIG. 9 is merely one example and is not limited thereto. Referring to FIG. 9, the cell switch command MAC CE may include a Target Config ID. The Target Config ID may be a target LTM candidate ID. That is, it may be cell identifier information that the terminal needs to change. Additionally, the cell switch command MAC CE may include a Timing Advance Command (TA). The TA command may indicate a valid TA value as a value from 0 to FFE. For example, if the TA command is a first value (e.g., FFF), the TA command field may indicate that there is no valid TA value for the target cell. Additionally, the cell switch command MAC CE may include a C field, and the C field may be a field indicating whether to perform contention-free random access. Additionally, it may include a Random Access Preamble index within the cell switch command MAC CE, and the Random Access Preamble index may indicate a CFRA preamble resource. Additionally, the SS / PBCH index within the cell switch command MAC CE may indicate an SSB for determining a RACH occasion. Additionally, the PRACH Mask index within the cell switch command MAC CE may indicate available RACH occasion locations.

[0130] FIG. 10 is a diagram illustrating the signaling of an LTM cell change completion step applicable to the present disclosure. Referring to FIG. 10, a terminal (1010) may perform a RACH-less procedure or a RACH procedure based on whether it possesses a valid TA of a target LTM candidate cell in an LTM cell change execution procedure, as described above.

[0131] Here, when the terminal (1010) attempts to change to a target LTM candidate cell through a RACH procedure, the terminal (1010) can complete the LTM cell change by sending an RRC Reconfiguration complete message to the network within the RACH procedure. On the other hand, when the terminal (1010) attempts to change to a target LTM candidate cell based on a RACH-less procedure, the terminal (1010) can complete the LTM cell change by sending an RRC Reconfiguration complete message to the network through the DG / CG.

[0132]

[0133] FIG. 11 is a diagram illustrating an inter-base station handover procedure applicable to the present disclosure.

[0134] For example, cell-level mobility can be triggered based on explicit RRC signaling. Referring to FIG. 11, a source base station (e.g., source gNB, 1120) can initiate a handover by transmitting a handover request message to a target base station (target gNB, 1130) via an Xn interface. The target base station (1130) can perform admission control and provide a new RRC configuration to the source base station (1120) via a handover request acknowledge message. The source base station (1120) can transmit the new RRC configuration information received from the target base station (1130) in an RRC reconfiguration message to the terminal (1110). The RRC reconfiguration message may include a cell identifier (e.g., Cell ID) and information necessary to connect to the target cell. As described above, the terminal (1110) can connect to the target cell by obtaining the information necessary to connect to the target cell without checking system information. For example, the RRC reconfiguration message may include information necessary for at least one of contention-based random access and contention-free random access operations. Additionally, the RRC reconfiguration message may include beam-specific information, but is not limited to such embodiments. Based on the RRC reconfiguration message, the terminal (1110) can change the RRC connection to the target base station (1130) and transmit an RRC reconfiguration complete message to the target base station (1130).

[0135] For example, in the case of a DAPS (dual active protocol stack) handover, the terminal (1110) can continue receiving downlink data from the source base station (1120) until the source cell connection is released. Additionally, the terminal (1110) can continue transmitting uplink data to the source base station (1120) until the random connection procedure to the target base station (1130) is completed.

[0136] Here, only the source PCell (primary cell) and the target PCell can use DAPS handover. For example, CA (carrier aggregation), DC (dual connectivity), SUL (supplementary uplink), Multi-TRP (transmission reception point), EHC, CHO (conditional handover), UDC, NR sidelink setup, and V2X sidelink setup may not be set by the target base station until the terminal's connection is disconnected by the source base station (1120) before the handover command is transmitted to the terminal (1110), and until the DAPS handover is completed. Here, handover methods triggered by RRC signaling other than DAPS handover may require the terminal to reset the MAC (medium access control) and RLC (radio link control). For example, when the terminal receives a handover command, the terminal may create a MAC entity for the target and establish an RLC entity. The establishment of RLC entities may be an operation that configures a DTCH (dedicated traffic channel) logical channel associated with each DRB (data radio bearer) associated with DAPS. Additionally, PDCP (packet data convergence protocol) entities may be reconfigured with security and ROHC (robust header compression) functions for each source and target in relation to each DRB associated with DAPS, and the reconfigured PDCP entities may be associated with RLC entities configured on the source and target, respectively, but are not limited to such operations.

[0137] For example, RRC handover with PDCP entity reset and RRC handover without PDCP entity reset may be supported. Here, for DRBs using RLC AM (acknowledge mode), which is a mode that uses a response to data transmission, the PDCP layer may be re-established with a security key change. Alternatively, for DRBs using RLC AM mode, the PDCP layer may initiate a data recovery procedure without a security key change.

[0138] Also, as an example, the PDCP layer for DRBs using RLC UM (unacknowledged mode), a mode that does not use acknowledgments for data transmission, can be re-established with a security key change. Alternatively, the PDCP layer for DRBs using RLC UM mode can be maintained without a security key change. The PDCP layer for SRBs (signaling radio bearers) can be maintained by discarding stored PDCP PDUs (protocol data units) and SDUs (service data units) without a key change, or it can be re-established with a key change.

[0139] In addition, as an example, if the target base station uses the same DRB configuration as the source base station, sequence delivery or duplication avoidance can be guaranteed in the case of data forwarding during the handover process.

[0140] In addition, as an example, a timer-based handover failure procedure may be supported. An RRC connection re-establishment procedure, excluding CHO, DAPS, and LTM cell change scenarios, may be used to recover the connection from a handover failure.

[0141] For example, if the DAPS handover fails, the terminal can return to the source cell configuration and resume the connection with the source cell. If the source cell link is not released, the terminal can report the DAPS handover failure without performing the RRC connection re-establishment procedure.

[0142] As another example, in the case where the CHO fails—specifically when the initial attempt to execute the CHO fails or the handover fails—the terminal can perform cell selection. Here, if the cell selected by the terminal is a candidate cell for the CHO and the network is configured to have the terminal attempt the CHO after a handover / CHO failure, the terminal can execute the CHO. Conversely, if the network is not configured to have the terminal attempt the CHO after a handover / CHO failure, the terminal can perform the RRC connection re-establishment procedure.

[0143] As another example, in the case of an LTM failure where an attempt to execute an LTM fails or a handover fails, the terminal can perform cell selection. Here, if the cell selected by the terminal is an LTM candidate cell and the network is configured to have the terminal attempt an LTM after a handover / LTM execution failure, the terminal can execute the LTM. On the other hand, if the network is not configured to have the terminal attempt an LTM after a handover / LTM execution failure, the terminal can perform the RRC connection re-establishment procedure.

[0144]

[0145] Beam level mobility can be triggered without explicit RRC signaling. Beam level mobility can be applied within a single cell or between cells. When beam level mobility is applied between cells, it may be inter-cell beam management (ICBM). For ICBM, the terminal may transmit and receive dedicated channels / signals via a transmission reception point (TRP) associated with a PCI other than the serving cell's physical cell ID (PCI). Conversely, non-dedicated channels / signals may be received only via a TRP associated with the serving cell's PCI. The base station may provide the terminal with measurement settings via RRC signaling, including SSB / CSI (synchronization signal block / channel state information) resources, resource sets, and settings for reporting and trigger requirements for channel / interference measurement reporting. In ICBM, measurement settings may include SSB resources associated with the serving cell's PCI and other PCIs. Beam level mobility can be handled by control signaling of the physical and MAC layers, and the RRC layer may not need to know which beam is currently in use. Additionally, SSB-based beam level mobility can operate based on the SSB associated with the initial DL BWP (bandwidth part). Here, CSI-RS-based beam level mobility operation can be performed in other DL BWPs.

[0146]

[0147] Conditional handover (CHO) is an operation in which a handover is performed only when specific conditions are met. For example, in conventional handover procedures, the decision to perform a handover was essentially determined by the terminal and the network. In other words, signaling between the network and the terminal may have been required for the handover to occur. However, in areas outside the cell or dead zones where signal strength changes rapidly, signaling exchange between the terminal and the network may be difficult, potentially leading to a handover failure.

[0148] Considering the above points, the terminal may perform a conditional handover (CHO) operation to perform a handover when specific conditions are satisfied. That is, if one or more handover execution conditions are satisfied, the terminal may perform a handover operation based on the CHO. Specifically, the terminal may receive a CHO configuration and, based thereon, begin evaluating the execution conditions of the CHO. For example, the terminal may stop evaluating execution conditions when a previous handover or conditional handover is performed.

[0149] The CHO configuration may include configurations of conditional handover candidate cells generated by candidate base stations (e.g., candidate gNB(s)) and execution conditions generated by the source base station (e.g., Source gNB). The execution conditions of the CHO may consist of one or more trigger conditions (e.g., CHO event A3 / A5). For example, when evaluating the conditional handover conditions of a single candidate cell, only one Reference Signal (RS) type is supported, and up to two different trigger elements (e.g., RSRP, RSRQ, SINR) may be set simultaneously, but are not limited thereto. As another example, the terminal may perform a handover procedure if it receives a handover command before a specific conditional handover execution condition is satisfied. Here, while the conditional handover is in progress, the terminal may not perform monitoring of the source cell.

[0150]

[0151] FIG. 12 is a diagram illustrating a procedure for performing an intra-AMF / UPF conditional handover applicable to the present disclosure. Referring to FIG. 12, in an intra-NR RAN conditional handover, message exchange between base stations can be performed without signaling of the core network (e.g., 5GC) during the conditional handover preparation and execution phases. During the conditional handover, resource release at the source base station (e.g., Source gNB) can be triggered by the target base station (e.g., Target gNB).

[0152] As a specific example, when the terminal (1210) establishes a connection or updates the TA (timing advance) for the last time, the access management function (AMF, 1250) may provide mobility control information to the source base station (1220). For example, information regarding roaming and access restrictions may be included in the terminal information (UE context) within the source base station (1220). Next, the source base station (1220) may set a measurement configuration for the terminal (1210) so that the terminal (1210) performs measurement procedures and reports. Here, the source base station (1220) may decide to perform a conditional handover based on the measurement report according to the measurement configuration if certain conditions are satisfied. The source base station (1220) may request a conditional handover to one or more candidate cells included in one or more base stations. For example, the source base station (1220) may transmit a handover request message to each of the cells. After that, the target base station (1230) can perform an admission control operation. For example, when slice information is transmitted to the target base station (1230), the target base station (1230) may recognize the slice and perform admission control. Here, if there are PDU sessions associated with slices that the target base station (1230) does not support, the target base station (1230) may reject the PDU sessions. After that, the target base station (1230) can transmit a handover request response to the source base station (1220). Candidate target base stations (1240) can also transmit a handover request response to the source base station (1220).For example, each candidate base station (1240) may transmit a conditional handover request acknowledge message to the source base station (1220), including conditional handover candidate cell configuration information. Then, the source base station (1220) may transmit an RRC reconfiguration message to the terminal (1210), including conditional handover execution conditions and configuration information of the conditional handover candidate cells. The terminal (1210) may transmit an RRC reconfiguration complete message to the source base station (1220). Here, if early data forwarding is applied, the source base station (1220) may transmit an early status transfer message. The early status transfer message may be for DAPS (dual active protocol stack) operation, but is not limited thereto.

[0153] After receiving conditional handover setting information, the terminal (1210) maintains a connection with the source base station (1220) and can evaluate conditional handover execution conditions for conditional handover candidate cells. If the execution condition is satisfied for at least one conditional handover cell, the terminal (1210) can disconnect from the source base station (1220) and apply the stored setting information to the selected candidate cell. Afterward, the terminal (1210) can perform synchronization with the candidate cell and complete the RRC handover procedure by sending an RRC configuration complete message to the target base station (1230). After completing the RRC handover procedure, the terminal (1210) can release the stored conditional handover setting information.

[0154] Here, the target base station (1230) may send a handover success message to the source base station (1220) to indicate whether the terminal (1210) has successfully connected to the target cell. In response to this, the source base station (1220) may send an SN status transfer message to the target base station (1230). If the source base station (1220) cancels the conditional handover of the terminal (1210), it may send a handover cancel message to other candidate target base stations (1240) or other signaling connection entities.

[0155] The target base station (1230) can send a path switch request message to the AMF (1250). The path switch request message may be a message that triggers the AMF (1250) to change the DL data path of the core network to the target base station (1230). Additionally, it may allow the establishment of an interface (e.g., NG-C) toward the target base station (1230).

[0156] The core network (e.g., 5GC) changes the DL data path to the target base station (1230), and the user plane function (UPF, 1260) can release U-plane / TNL resources toward the source base station (1220) after transmitting one or more "end marker" packets per PDU session / tunnel to the existing path toward the source base station (1220). The AMF (1250) can indicate that the path change is complete by sending a path switch request acknowledge message to the target base station (1230). The target base station (1230) can notify the completion of the handover by sending a UE context release message to the source base station (1220) based on the path switch request acknowledge received from the AMF (1250). Afterward, the source base station (1220) can release the radio and control plane (C-Plane) resources associated with the terminal.

[0157]

[0158] Next, we can consider methods for performing beam management. That is, beam management can be performed in wireless communication systems. In particular, beam management technology may be essential in the FR2 (frequency range 2) (24250 MHz - 52600 MHz) band. On the other hand, beam management may not be used in the FR1 (frequency range 1) (410 MHz - 7125 MHz) band, which uses a band similar to existing wireless communication systems (e.g., LTE), but is not limited thereto.

[0159] For example, spatial domain control can be performed based on digital domain precoding technology for effective communication between a base station and a terminal. The base station can select and use a preferred precoding matrix from the UL / DL codebook, which can be applied to the transmission of beams with a specific directionality. For example, in 5G FR2, since the path loss experienced by the signal can be significant, it may be required to use a narrower beam. Here, analog domain beam control using phase shifting may be used, but is not limited thereto.

[0160] As another example, DL beam management in a wireless communication system can utilize a transmission configuration indication (TCI) framework. Here, the beam of a specific channel / signal (e.g., PDSCH, PDCCH, CSI-RS) that a terminal must receive can be indicated by the TCI. The TCI can consist of a source reference signal (RS) and a quasi-colocation (QCL) type to be applied. For example, a base station can transmit downlink control information (DCI) regarding physical downlink shared channel (PDSCH) scheduling to a terminal, and the DCI may include the TCI used to receive the PDSCH. Upon receiving the DCI, the terminal can subsequently set analog beamforming coefficients based on the TCI indicated for PDSCH reception. In the above case, since the TCI is indicated solely for PDSCH reception, it can be used as an individual TCI framework. That is, an independent TCI can be indicated for each channel / signal reception (e.g., PDSCH, PDCCH, CSI-RS).

[0161] This individual per-channel beam indication framework can be applied in the same way to the uplink. For example, a base station can transmit a DCI for PUSCH (physical uplink shared channel) scheduling to a terminal. The DCI may include a sounding reference signal resource indicator (SRI) used for PUSCH transmission. Upon receiving the DCI, the terminal can set analog beamforming coefficients based on the SRI indicated for subsequent PUSCH transmission. In other words, the terminal can obtain independent beam indications for each channel / signal (e.g., PUSCH, PUCCH), just as it does for DL.

[0162] As another example, independent beam indication can be performed for each channel, allowing the base station to perform flexible configuration. However, control signaling to indicate the appropriate beam for each channel may increase, which can act as overhead for the base station. For example, in FR2 operation, the base station may use one or more beams to communicate with the terminal. Here, even if the base station sets mostly identical or similar beams, it is necessary to provide independent configuration for each channel, and consequently, overhead may increase. Considering the above points, a common beam indication operation for multiple channels can be applied in MIMO (multi-input multi-output) for UL / DL transmission and reception. Common beam indication (i.e., TCI state) can be performed through one of the integrated common TCI state pools configured by the upper layer. When a common TCI state is indicated, that indication is not used for a single specific channel but can be used for multiple channels / signals simultaneously. For example, the Common TCI state can be applied commonly to CSI-RS, CORESET, and PDSCH, and can also be applied to uplink channels such as PUSCH, PUCCH (physical uplink control channel), and SRS (sounding reference signal), but is not limited to such embodiments.

[0163] As another example, a base station can establish a joint TCI state pool through RRC signaling. Here, a common TCI state can be applied to multiple DL / UL channels. If the base station establishes a DL TCI state pool and a UL TCI state pool respectively, the common TCI state may be applied only to DL channels or only to UL channels.

[0164] For example, in a wireless communication system, both a joint TCI state pool and a separate TCI state pool may be supported. Here, the joint TCI state pool method can efficiently manage beams applicable to both DL and UL. On the other hand, the separate TCI state pool can simplify terminal operation by associating power control parameters used only in the uplink. That is, the terminal may perform power control procedures for TCI states associated only with the UL TCI state pool, but may not be limited to this.

[0165]

[0166] Based on the above, the following describes the operation to support LTM (L1 / L2 layer triggered mobility) in an intra-CU situation. For example, in wireless communication systems (e.g., Rel-19 Mobility enhancements), LTM operation is defined considering inter-CU situations, and event-based L1 measurement result reporting may be applied to reduce signaling overhead associated with existing periodic / non-periodic L1 measurement result reporting. For example, Table 7 below may be an LTM operation in an inter-CU situation applied in wireless communication systems, but is not limited thereto.

[0167] [Table 7]

[0168]

[0169]

[0170] The following describes the operation in which the terminal checks the conditions for triggering LTM, and if the conditions are satisfied, the terminal performs LTM on an LTM candidate cell.

[0171] For example, regarding LTM operations, the network may instruct the terminal to perform LTM by transmitting an LTM cell switch command MAC CE (medium access control control element). Here, in the case of conditional LTM, the terminal may perform the LTM operation according to certain conditions without receiving the LTM cell switch command MAC CE. That is, the terminal may need to perform the LTM operation without utilizing the information within the MAC CE, and an action may be required for this purpose.

[0172] FIG. 13 is a diagram illustrating a cell switch command MAC CE applicable to the present disclosure. Referring to FIG. 13, a terminal that receives an LTM cell switch command MAC CE can perform a random access procedure initialization. Specifically, if a random access resource is explicitly provided within the LTM cell switch command MAC CE, the terminal can perform a random access procedure by setting a 4-step RACH (random access channel) based on the explicitly provided random access resource. When the terminal performs a random access procedure, if a "ra-PreambleIndex" is explicitly provided in the "Random Access Preamble index" within the LTM cell switch command MAC CE, the terminal can set the preamble index to the transmitted preamble index (ra-PreambleIndex) within the LTM cell switch command MAC CE and select a synchronized signal block (SSB) transmitted together. Additionally, the terminal can perform preamble transmission by determining a possible PRACH occasion among the PRACH occasions allowed in the selected SSB according to the "PRACH Mask index" restriction indicated within the LTM cell switch command MAC CE.

[0173] Additionally, if the "Timing Advance Command" within the LTM cell switch command MAC CE is not set to FFF (fractional frequency factor), the terminal may apply the indicated "Timing Advance Command" to the PTAG (Primary timing advance group) and (re)start the time alignment timer. That is, the terminal may perform uplink time alignment using the timing advance value indicated in the LTM cell switch command MAC CE, unless the timing advance value indicated in the LTM cell switch command MAC CE is measured by the terminal.

[0174] As another example, if the "Timing Advance Command" within the LTM cell switch command MAC CE is set to FFF and the terminal successfully measures the timing advance, the terminal can apply the measured timing advance to the PTAG and (re)start the time alignment timer.

[0175] Additionally, the terminal may set the configured grant (CG) of the uplink for the LTM cell switch to CG type 1, but may not be limited thereto. If the SSB associated with the transmission configuration indicator (TCI) indicated by the "TCI state ID" field in the LTM cell switch command MAC CE is the same as the SSB associated with the configured uplink grant, the terminal may select the SSB associated with the TCI state indicated by the LTM cell switch command MAC CE and transmit the SSB index to the lower layer. That is, the terminal may determine that the configured uplink grant is valid. On the other hand, if the SSB associated with the TCI indicated by the "TCI state ID" field in the LTM cell switch command MAC CE is not the same as the SSB associated with the configured uplink grant, the terminal may determine that the configured uplink grant is invalid.

[0176] Additionally, when the terminal receives an LTM cell switch command, the terminal's MAC layer may indicate to the lower layer that an LTM cell switch procedure is to occur along with a target configuration ID. Here, the terminal may receive a request from the upper layer for a MAC reset. If the TAC (timing advance command) value within the LTM cell switch command is not FFF, or if the TAC value is FFF but the terminal successfully measures the timing advance to the indicated LTM target cell, the terminal may be deemed to apply the timing advance and perform a RACH-less LTM cell switch operation. That is, if the TAC value is indicated within the LTM cell switch command, or if the terminal successfully measures the TA (timing advance) of the target cell even if the TAC value is not indicated, the terminal may perform a cell switching operation without performing a random access procedure.

[0177] For example, the terminal may use an SSB associated with the TCI state indicated by the "TCI state ID" field within the LTM cell switch command for the configured grant selection of the first uplink transmission of the LTM candidate cell. Here, the LTM candidate cell may be an LTM candidate cell for the RACH-less LTM cell switch described above. The terminal may indicate the TCI state information within the LTM cell switch command to the lower layer, and LTM cell switching may be performed as described above.

[0178]

[0179] For example, regarding TCI and SSB, LTM TCI information (LTM TCI Info) may be included for each LTM candidate within the LTM configuration, and the parameters for this may be as shown in Table 8 below.

[0180] [Table 8]

[0181]

[0182]

[0183] For example, the TCI state ID indicated within the LTM cell switch command MAC CE may mean an identifier distinguishing one or more candidate TCI states within "ltm-DL-OrJointTCI-StateTO-AddModList", and the candidate TCI states may include the information in Table 9 below.

[0184] [Table 9]

[0185]

[0186]

[0187] Quasi-Colocation (QCL) can refer to cases where channels have similar characteristics. For example, regarding a single antenna port with a hypothetical antenna presumed to be experiencing the same channel, two different antenna ports may have similar channel characteristics in certain situations, even if they are not perfectly identical; in such cases, the two different antenna ports may be in a QCL relationship.

[0188] In wireless communication systems (e.g., NR), four QCL types (A, B, C, D) can be defined based on channel characteristics (e.g., Doppler shift, Doppler spread, average delay, delay spread, spatial Rx parameter). However, they are not limited to these. If a terminal recognizes that two antenna ports in a QCL relationship have similar channel characteristics, it can recognize the channel of the other antenna port through the channel information of one antenna port. In the QCL types, Types A, B, and C are used for channel estimation, while Type D can be used for beam management in beamforming. For example, when a terminal receives a downlink data channel or a control channel through a specific antenna port, the terminal can utilize the channel characteristics of the SSB or CSI-RS (channel state information reference signal) ports in a QCL relationship. Here, the QCL relationship between reference signals can be indicated through the transmission configuration index (TCI) described above.

[0189]

[0190] FIG. 14 is a diagram showing a candidate cell TCI state activation / deactivation MAC CE applicable to the present disclosure.

[0191] Referring to FIG. 14, the candidate cell ID may be an identifier of an LTM candidate cell to which the corresponding MAC CE can be applied, and may correspond to "ltm-CandidateId". Additionally, in FIG. 14, the Pi field may indicate whether a TCI codepoint indicates multiple TCI states or a single TCI state. For example, if the Pi field value is 1, the i-th TCI codepoint may include both a DL TCI state and an UL TCI state. On the other hand, if the Pi field value is 0, the i-th TCI codepoint may include only a DL / joint TCI state or an UL TCI state. In FIG. 14, the D / U field may indicate whether a TCI state ID within the same octet indicates a DL / joint TCI state or a UL TCI state. When the D / U field value is 1, the TCI state ID may indicate a DL / joint TCI state, and when the D / U field value is 0, the TCI state ID may indicate a UL TCI state.

[0192] Additionally, in FIG. 14, the TCI state ID may indicate a TCI state distinguished by a TCI state ID (TCI-StateId) within "ltm-DL-OrJointTCIStateToAddModList" or a TCI-uplink-state ID (TCI-UL-StateId) within "ltm-UL-TCI-StatesToAddModList". For example, if the D / U field is 1, it indicates a TCI state ID of 7 bits in length, and if the D / U field is 0, the remaining 6 bits excluding the first bit may indicate a TCI-uplink-state ID (TCI-UL-StateId).

[0193] For example, Table 10 below may be a TCI state indicated by a candidate TCI state enable / disable MAC CE. However, Table 10 is merely one example for convenience of explanation and is not limited thereto.

[0194] [Table 10]

[0195]

[0196]

[0197] The following describes the target cell access operation for conditional LTM. For example, a method for indicating a TAC may be required in relation to the target cell access operation. Specifically, a method for recognizing the TACs of at least one candidate cell in advance for a terminal to perform an uplink transmission to a triggered target cell may be required, and this is described below.

[0198] FIG. 15 is a diagram illustrating a conditional LTM operation applicable to the present disclosure. Referring to FIG. 15, in a conditional LTM, signaling for an LTM cell switch execution step and a complete step can be performed after an LTM preparation step and an early sync step.

[0199] Specifically, during the LTM preparation phase, the source cell (1520) can set an LTM configuration for the terminal (1510) based on an L3 measurement report. The LTM configuration may include RRC configuration information for one or more candidate cells (1530, 1540), and the LTM configuration may be set for the terminal (1510) through an RRC reconfiguration message. The RRC reconfiguration message may set event conditions for LTM execution for one or more candidate cells (1530, 1540). Afterward, the terminal can perform DL / UL pre-synchronization with one or more candidate cells (1530, 1540). When the terminal (1510) performs UL pre-synchronization, the terminal (1510) may send a preamble to one or more candidate cells (1530, 1540) and may not receive a RAR (random access response). After that, in the LTM cell switch execution and complete phase, the terminal (1510) can check the L1 measurement results of the reference signals (e.g., SSB, CSI-RS) of one or more candidate cells (1530, 1540) and check whether the set event conditions are satisfied. If the event conditions are satisfied, the terminal (1510) determines the candidate cell satisfying the conditions as the target cell (1530) and can perform the LTM operation. That is, the terminal (1510) can complete the LTM procedure by sending an RRC reconstruction message to the target cell (1530).

[0200] Here, if the terminal (1510) determines that the TA for the target cell (1530) is valid, the terminal (1510) can transmit an RRC reconfiguration complete message to the target cell through a configured grant uplink resource. That is, since the TA for the target cell is valid, the terminal (1510) can transmit the message through the configured grant uplink resource without a RACH procedure. On the other hand, if the terminal (1510) determines that the TA for the target cell (1530) is invalid, the terminal (1510) can perform a random access procedure to the target cell (1530) through a designated RACH resource.

[0201] For example, the LTM cell switch command MAC CE may contain information necessary when the terminal switches to a target LTM cell, and the terminal can perform cell switching to the target cell based on the LTM cell switching command MAC CE. However, in the case of conditional LTM, the terminal (1510) does not receive the LTM cell switch command MAC CE. That is, since the terminal (1510) performs cell switching by checking the L1 measurement results of reference signals (e.g., SSB, CSI-RS) of one or more candidate cells (1530, 1540) and checking whether the set event conditions are satisfied, a method to obtain information necessary when switching to the target LTM cell may be required. Here, the terminal may receive the LTM TAC MAC CE to check the TA of one or more candidate cells in relation to conditional LTM operation. As another example, the terminal may set a TCI status ID for uplink transmission to the target cell.

[0202]

[0203] FIG. 16 is a diagram illustrating a method in which an LTM TAC MAC CE is delivered to a terminal based on a conditional LTM applicable to the present disclosure. Referring to FIG. 16, a TAC for one or more candidate cells based on a conditional LTM can be delivered to a terminal (1610).

[0204] More specifically, in relation to LTM operation, an LTM preparation phase and an early synchronization phase may be performed, as described above. In the early synchronization phase, the terminal (1610) may perform DL / UL pre-synchronization with one or more candidate cells. When the terminal (1610) performs UL pre-synchronization, the source cell (1620) may transmit a PDCCH (physical downlink control channel) order to the terminal (1610) instructing the transmission of a preamble to one or more candidate cells (1630, 1640). The terminal (1610) may transmit the preamble to one or more candidate cells (1630, 1640) through the RACH resource indicated in the PDCCH order. However, the terminal (1610) may not receive a RAR after transmitting the preamble to one or more candidate cells (1630, 1640).

[0205] One or more candidate cells (1630, 1640) that have received a preamble from the terminal (1610) can transmit a TAC to the source cell (1620). That is, the source cell (1620) can receive a TAC from one or more candidate cells (1630, 1640). Then, the source cell (1620) can include the TAC received from one or more candidate cells (1630, 1640) in an LTM TAC MAC CE and transmit it to the terminal (1610), thereby allowing the terminal (1610) to receive the TAC of one or more candidate cells (1630, 1640).

[0206] After that, in the LTM cell switch operation and completion stage, the terminal (1610) checks the L1 measurement results of the reference signals (e.g., SSB, CSI-RS) of one or more candidate cells (1630, 1640), and if the event condition is satisfied based on the L1 measurement results, determines the candidate cell satisfying the condition as the target cell and can perform LTM. That is, the terminal (1610) can complete the LTM procedure by transmitting an RRC reconstruction message to the target cell, as described above.

[0207] Here, if the terminal (1610) determines that the TA for the target cell is valid, the terminal (1610) can transmit an RRC reconfiguration complete message to the target cell through a configured grant uplink resource. That is, since the TA for the target cell is valid, the terminal (1610) can transmit the message through the configured grant uplink resource without a RACH procedure. On the other hand, if the terminal (1610) determines that the TA for the target cell (1630) is invalid, the terminal (1610) can perform a random access procedure to the target cell through a designated RACH resource.

[0208] For example, the terminal can determine the validity of the TA for the target cell through the information within the LTM TAC MAC CE received in the step described above. As a specific example, FIG. 17 is a diagram showing an LTM TAC MAC CE applicable to the present disclosure. Referring to FIG. 17, the LTM TAC MAC CE may indicate the TAC of one or more candidate cells. Upon receiving the LTM TAC MAC CE, the terminal may maintain TAC information of candidate cells corresponding to the Target Config ID, and each field may be as shown in Table 11 below. For example, the LTM TAC MAC CE may include the Target Config ID as an identifier distinguishing one or more candidate cells within the LTM configuration. Additionally, TAC values ​​for uplink synchronization for each of the candidate cells corresponding to the Target Config ID may be included.

[0209] [Table 11]

[0210]

[0211]

[0212] For example, a MAC CE format for transmitting the TAC for a single candidate cell may be as shown in FIG. 17(a). On the other hand, a MAC CE format for transmitting the TAC for two or more candidate cells may be as shown in FIG. 17(b). Up to eight candidate cells may be considered within the LTM configuration. Therefore, a format for transmitting the TAC for two or more candidate cells may be up to 16 octets. That is, N can be up to 16. Although FIG. 17 describes the use of two octets to indicate the TAC information of a single candidate cell, it is not limited to this and may have other octet sizes and is not limited to a specific form.

[0213] In addition, as an example, the terminal may configure a time alignment timer (TAT) as an RRC parameter to maintain the TAC of a serving cell, and may (re)start the TAT upon receiving the TAC. Here, the TA may be valid while the TAT is operating. The terminal may set one TAT RRC parameter and, upon receiving the LTM TAC MAC CE, may operate the TAT for the corresponding candidate cells (LTM-CandidateId), and the one TAT RRC parameter may be configured as shown in Table 12.

[0214] [Table 12]

[0215]

[0216]

[0217] As another example, the terminal may receive multiple TAT RRC parameters. That is, the terminal may receive one or more TATs for one or more candidate cells within the LTM configuration. In the above case, the LTM TAC MAC CE may include a TAT ID that operates in conjunction with the TAC. As an example, FIG. 18 is a diagram showing an LTM TAC MAC CE format when multiple TAT RRC parameters applicable to the present disclosure are set to the terminal. Referring to FIG. 18, when the terminal receives the LTM TAC MAC CE, it may activate a corresponding timer through the TAT identifier of the corresponding candidate cell (LTM-CandidateId). That is, the terminal may receive multiple TATs through RRC signaling, and among the multiple TATs, a TAT ID that operates in conjunction with the TAC may be included in the LTM TAC MAC CE and transmitted to the terminal. As an example, a MAC CE format for transmitting a TAC for a single candidate cell may be as shown in FIG. 18(a). On the other hand, the MAC CE format for transmitting TAC for two or more candidate cells may be as shown in FIG. 18(b), and may include a TAT ID corresponding to each candidate cell. Up to eight candidate cells may be considered within the LTM configuration, and the LTM TAC MAC CE format may be determined based on this. Although FIG. 18 describes the use of three octets to indicate the TAC information of a single candidate cell, it is not limited thereto and may have different octet sizes and is not limited to a specific form. Additionally, as described above, the case in which a terminal receives multiple TAT RRC parameters may be as shown in Table 13 below, but is not limited thereto.

[0218] [Table 13]

[0219]

[0220]

[0221] Next, a method for selecting a configured grant (CG) occasion of the target cell can be considered. For example, the terminal may select a CG occasion to perform an uplink transmission to the triggered target cell. Table 14 below may be an operation for an uplink grant configured as CG type 1 for an LTM cell switch, but is not limited thereto.

[0222] More specifically, CG type 1 for LTM can be configured on the terminal. Here, if the SSB associated with a specific CG occupancy is the same as the SSB associated with the TCI state indicated by the TCI state field within the LTM cell switch command MAC CE, the terminal may select the corresponding SSB and indicate the SSB index to the lower level. That is, the terminal may determine that the corresponding CG occupancy is valid. To perform RACH-less LTM, the terminal determines the validity of the CG occupancy, and if valid, may perform the LTM procedure through the SSB associated with the TCI state of the LTM cell switch command MAC CE. For example, in the case of conditional LTM, since the aforementioned LTM cell switch command MAC CE is absent, the terminal may perform an operation to determine whether a specific CG occupancy is valid, and this is described below.

[0223] For example, in the case of SDT (small data transmission) CG, the terminal may perform an operation to compare SSB RSRP (reference signal received power) to select a good beam. In relation to the SDT CG operation, the terminal may compare the SSB RSRP with a set threshold value, and if the RSRP of the SSB associated with a specific occupancy is lower than the threshold value, it may determine that the CG occupancy is invalid.

[0224] In the case of LTM CG, unlike SDT CG, LTM MAC CE can indicate a good beam, so the RSRP of the beam may not be evaluated. For example, in the case of RACH-less CG-based LTM operation, the terminal can determine that a specific CG occupancy is valid if the SSB index associated with the TCI status ID indicated by the LTM MAC CE is the same as that CG occupancy, as described above.

[0225] [Table 14]

[0226]

[0227]

[0228] FIG. 19 is a diagram showing the relationship between SSB and CG occupations applicable to the present disclosure.

[0229] Referring to FIG. 19, the number of SSBs associated per CG occupation within a CG configuration can be determined. Depending on "ltm-SSB-perCG" within the CG configuration, CG occupations and SSBs can be associated within an association period. As a specific example, referring to FIG. 19(a), there may be a case where "ltm-SSB-perCG" is one, and one SSB may be sequentially associated with each CG occupation (1911, 1912, 1913, 1914, 1915) within an association period. On the other hand, FIG. 19(b) there may be a case where "ltm-SSB-perCG" within the CG configuration is half. That is, within each CG occupation (1921, 1922, 1923, 1924, 1925) within the association period, two SSBs can be sequentially associated.

[0230] For example, when the RACH-lease procedure is performed as a conditional LTM procedure, as described above, the LTM MAC CE is not transmitted, so it may be necessary to perform an operation to determine whether the CG occupancy is valid at the terminal.

[0231] Here, the terminal may select an SSB within the event evaluation without measuring the RSRP of the CG occupancy. More specifically, the terminal may check for event conditions regarding the signal strength of at least one of the serving cell and neighboring cells, and perform a conditional LTM operation if the event conditions are met. For example, the event that occurred may be performed on a beam basis, and the validity of the CG occupancy may be an operation using the beam used for the event evaluation.

[0232] For example, in an LTM procedure, a TCI status ID within the LTM cell switch command MAC CE is indicated, and the terminal can determine the validity of the CG occupancy based on the indicated TCI status ID beam. However, in a conditional LTM procedure, since there is no LTM cell switch command MAC CE, the terminal may not have an indicated TCI status ID and may not be able to determine the validity of the CG occupancy.

[0233] The terminal can evaluate beams through an event evaluation procedure in a conditional LTM and perform a conditional LTM. Here, the event evaluation procedure can be performed while the terminal knows which beam has a good RSRP. The terminal may be able to determine the validity of a CG occupancy based on beams that satisfy event conditions, and the specific event conditions may be as shown in Table 15 below.

[0234] Referring to Table 15, the event condition may be when the signal strength of the serving cell beam becomes weaker than the threshold value. As another example, it may be when the signal strength of the neighboring cell beam is greater than the offset of the serving cell beam's signal strength. As yet another example, it may be when the signal strength of the neighboring cell beam becomes stronger than the threshold value. As yet another example, it may be when the signal strength of the serving cell beam becomes weaker than threshold 1 and the signal strength of the neighboring cell beam becomes stronger than threshold 2. However, Table 15 is only one example, and other cases may be considered, and it may not be limited to a specific form.

[0235] [Table 15]

[0236]

[0237]

[0238] FIG. 20 is a diagram illustrating a RACH-less conditional handover procedure applicable to the present disclosure.

[0239] Referring to FIG. 20, an LTM preparation phase and an early synchronization phase may be performed in relation to the LTM operation, as described above. In the early synchronization phase, the terminal (2010) may perform DL / UL pre-synchronization with one or more candidate cells. When the terminal (2010) performs UL pre-synchronization, the source cell (2020) may transmit a PDCCH order to the terminal (2010) instructing the transmission of a preamble to one or more candidate cells (2030, 2040). The terminal (2010) may transmit the preamble to one or more candidate cells (2030, 2040) through the RACH resource indicated in the PDCCH order. However, the terminal (2010) may transmit the preamble to one or more candidate cells (2030, 2040) and not receive the RAR.

[0240] One or more candidate cells (2030, 2040) that have received a preamble from the terminal (2010) can transmit a TAC to the source cell (2020). That is, the source cell (2020) can receive a TAC from one or more candidate cells (2030, 2040). Then, the source cell (2020) can include the TAC received from one or more candidate cells (2030, 2040) in an LTM TAC MAC CE and transmit it to the terminal (2010), thereby allowing the terminal (2010) to receive the TAC of one or more candidate cells (2030, 2040).

[0241] After that, in the LTM cell switch operation and completion stage, the terminal (2010) checks the L1 measurement results of the reference signals (e.g., SSB, CSI-RS) of one or more candidate cells (1630, 1640), and if the event condition is satisfied based on the L1 measurement results, determines the candidate cell satisfying the condition as the target cell and can perform LTM. That is, the terminal (2010) can complete the LTM procedure by transmitting an RRC reconstruction message to the target cell, as described above.

[0242] Here, if the terminal (2010) determines that the TA for the target cell is valid, the terminal (2010) can transmit an RRC reconfiguration complete message to the target cell through a configured grant uplink resource. That is, since the TA for the target cell is valid, the terminal (2010) can transmit a message through the configured grant uplink resource without a RACH procedure. On the other hand, if the terminal (2010) determines that the TA for the target cell (2030) is invalid, the terminal (2010) can perform a random access procedure to the target cell through a designated RACH resource.

[0243] Here, for example, the terminal can continuously monitor whether a configured LTM event is satisfied. The terminal can continuously perform event evaluation, and in FIG. 20, this may be the case where candidate cell 1 (2030) satisfies the condition. However, this is for convenience of explanation only and is not limited thereto. Afterward, the terminal can perform a validity evaluation operation for a specific CC occasion (CG occasion validity check). For example, the beams available in candidate cell 1 (2030) may be beam A, beam B, beam C, and beam D, and among these beams, there may be one or more beams that satisfy the condition during the event evaluation process. As a specific example, if only beam C satisfies the condition, the terminal (2010) can perform uplink transmission through the CG occasion associated with beam C. As another example, if beams C and D satisfy the conditions, the terminal (2010) can perform an uplink transmission to candidate cell 1 (2030) through the CG occupation that is associated with at least one of beams C and D and arrives first. The terminal (2010) can transmit an RRC reconfiguration completion message to the corresponding CG occupation.

[0244] That is, if there are multiple beams satisfying the condition, the terminal may perform uplink transmission through the first arriving CG occupation associated with at least one of the beams satisfying the condition. As another example, the terminal may perform uplink transmission through the first arriving CG occupation among the CG occupations associated with the beam that has the highest signal strength among the beams satisfying the condition. As an example, the beam described above may be a reference signal corresponding to at least one of SSB and CSI-RS.

[0245] More specifically, referring to FIG. 20, SSBs 1, 3, 4, and 7 may be considered as possible beams (SSBs) in candidate cell 1 (2030), and among these beams, the case where the beam satisfying the event evaluation condition is SSB 7 may be considered. Here, the terminal (2010) may perform an uplink transmission to candidate cell 1 (2030) through a CG occupation associated with SSB 7. However, this is merely an example for convenience of explanation and is not limited thereto.

[0246] As another example, consider the case where there are available beams (CSI-RS) in candidate cell 1 (2030), namely CSI-RS 5, 7, 10, and 14, and among them, the beam satisfying the event evaluation condition is CSI-RS 10. The terminal (2010) can perform uplink transmission to candidate cell 1 (2030) through a CG occupation associated with CSI-RS 10. However, this is merely an example for convenience of explanation and is not limited thereto. As another example, when determining the validity of a CG occupation, the terminal can identify an SSB associated with a CSI-RS beam satisfying the event evaluation condition and determine that the CG occupation associated with that SSB is valid, but is not limited to this embodiment.

[0247] In the LTM procedure, a TCI status ID within the LTM cell switch command MAC CE is indicated, and the terminal can determine the validity of the CG occupancy based on the indicated TCI status ID beam, as described above. However, in the conditional LTM procedure, since there is no LTM cell switch command MAC CE, the TCI status ID may not be indicated to the terminal, and taking this into account, the terminal can evaluate the validity of the CG occupancy through an event evaluation procedure as described above in the conditional LTM.

[0248] The terminal evaluates the beam through an event evaluation procedure and operates a conditional LTM, so it can recognize which beam's RSRP is good, and through this, it can perform an operation to determine the validity of the CG occupancy based on the beam that satisfies the event condition.

[0249] For example, if the terminal satisfies the event condition based on the conditional LTM, and the TAC of the candidate cell is valid, cell switching can be performed through the RACH-less procedure, as described above. As described above, the validity of the CG occupancy was determined based on the beam satisfying the event evaluation condition, but below, the validity of the CG occupancy can be verified by performing a measurement of the SSB associated with the CG occupancy.

[0250] More specifically, as shown in FIG. 19(b), when two SSBs are associated with each CG occupancy, the terminal can check the RSRP of two associated reference signals (e.g., SSB 1 and SSB 2, SSB 3 and SSB 4) in a specific CG occupancy. The terminal can determine that the CG occupancy is valid if at least one reference signal is greater than a threshold value. The terminal can direct the reference signal greater than the threshold value to the lower layer.

[0251]

[0252] As another example, conditional LTM may be a method for a terminal to quickly perform an LTM operation without an LTM operation instruction from the network when the terminal satisfies a configured event. Here, even if the terminal performs a conditional LTM operation, it does not necessarily mean that it does not report L1 measurement results. That is, the terminal can transmit L1 measurement result reports to the network, and the network can recognize the measurement results reported by the terminal. Therefore, based on the L1 measurement results, the network can inform the terminal of a suitable (or best) beam for one or more candidate cells and associated information (e.g., TCI state ID). If a beam exists that satisfies the conditional LTM condition, the terminal can determine the validity of the CG occupancy by deriving the TCI state ID associated with that beam.

[0253] FIG. 21 is a diagram illustrating a RACH-less conditional handover procedure applicable to the present disclosure.

[0254] Referring to FIG. 21, an LTM preparation phase and an early synchronization phase may be performed in relation to the LTM operation, as described above. In the early synchronization, the terminal (2110) may perform DL / UL pre-synchronization with one or more candidate cells. When the terminal (2110) performs UL pre-synchronization, the source cell (2120) may transmit a PDCCH order to the terminal (2110) instructing the transmission of a preamble to one or more candidate cells (2130, 2140). The terminal (2110) may transmit the preamble to one or more candidate cells (2130, 2140) through the RACH resource indicated in the PDCCH order. However, the terminal (2110) may transmit the preamble to one or more candidate cells (2130, 2140) and not receive the RAR.

[0255] Here, one or more candidate cells (2130, 2140) that have received a preamble from the terminal (2110) can transmit a TAC to the source cell (2120). That is, the source cell (2120) can receive a TAC from one or more candidate cells (2130, 2140). Then, the source cell (2120) can include the TAC received from one or more candidate cells (2130, 2140) in an LTM TAC MAC CE and transmit it to the terminal (2110), thereby allowing the terminal (2110) to receive the TAC of one or more candidate cells (2130, 2140).

[0256] Subsequently, in the LTM cell switch operation and completion stage, the terminal (2110) checks the L1 measurement results of reference signals (e.g., SSB, CSI-RS) of one or more candidate cells (1630, 1640), and if the event condition is satisfied based on the L1 measurement results, determines the candidate cell satisfying the condition as the target cell and can perform LTM. The terminal (2110) can complete the LTM procedure by transmitting an RRC reconstruction message to the target cell, as described above.

[0257] Here, if the terminal (2110) determines that the TA for the target cell is valid, the terminal (2110) can transmit an RRC reconfiguration complete message to the target cell through a configured grant uplink resource. That is, since the TA for the target cell is valid, the terminal (2110) can transmit the message through the configured grant uplink resource without a RACH procedure. On the other hand, if the terminal (2110) determines that the TA for the target cell (2130) is invalid, the terminal (2110) can perform a random access procedure to the target cell through a designated RACH resource.

[0258] For example, the terminal (2110) may perform L1 measurement reports for one or more candidate cells. The L1 measurement reports may be performed periodically or reported from the terminal (2110) to the source cell (2120) in an event-based manner. The terminal (2110) may perform L1 measurements of reference signals of one or more candidate cells and report the results through at least one of PUCCH (physical uplink control channel) and PUSCH (physical uplink shared channel) according to a set method (periodic method / event-based reporting method).

[0259] The source cell (2120) can set conditional LTM and TCI status IDs for one or more candidate cells based on an L1 measurement report obtained from the terminal (2110). For example, the source cell (2120) can provide an RRC reconstruction message containing conditional LTM and TCI status IDs for the candidate cells to the terminal (2110).

[0260] For example, the terminal can continuously monitor whether a configured LTM event is satisfied. That is, the terminal can continuously perform event evaluation, and in FIG. 21, this may be the case where candidate cell 1 (2130) satisfies the condition. However, this is for convenience of explanation only and is not limited thereto. Afterward, the terminal can perform a validity evaluation operation for a specific CC occasion (CG occasion validity check). For example, the beams available in candidate cell 1 (2130) may include beam A, beam B, beam C, and beam D, and among these beams, there may be one or more beams that satisfy the condition during the event evaluation process. As a specific example, if only beam C satisfies the condition, the terminal (2110) can identify a valid CG occasion based on the TCI status ID of candidate cell 1 (2130) associated with beam C, and perform uplink transmission at that CG occasion. As another example, if beams C and D satisfy the conditions, the terminal (2110) can identify a valid CG location based on the TCI status ID of the candidate cell (2130) configured with beams C and D, and perform an uplink transmission to candidate cell 1 (2130) through the CG location. That is, the terminal (2110) can send an RRC reconfiguration completion message to the CG location.

[0261] That is, if there are multiple beams satisfying the conditions, the terminal may determine the validity of a CG occupancy based on the beams satisfying the conditions and the TCI status ID of the configured candidate cell 1, and perform uplink transmission through the occupancy. As another example, the terminal may identify a valid CG occupancy based on the TCI status ID of the configured candidate cell (2130) associated with the beam with the highest signal strength among the beams satisfying the conditions, and perform uplink transmission through the CG occupancy. As an example, the beam described above may be a reference signal corresponding to at least one of SSB and CSI-RS.

[0262] Here, a case can be considered in which the validity of a CG occupancy is determined based on the TCI state ID of a candidate cell. The TCI state framework may be configured with a pool of possible TCI states by the network, and a portion may be activated by the network to indicate a TCI state ID used for actual transmission and reception.

[0263] For example, in a conditional LTM, the TCI status of a candidate cell can be indicated solely by RRC-based operations. That is, TCI status IDs corresponding to the available beams of the candidate cell can be indicated respectively. Here, if the available beams of the candidate cell do not change, additional signaling may not be required. As another example, in a conditional LTM, the TCI status of a candidate cell can be indicated by RRC and MAC CE-based operations. Specifically, the current TCI status ID of the candidate cell can be indicated and managed, but if the optimal beam changes due to terminal movement, signaling to change the TCI status ID can be indicated via MAC CE.

[0264] As a specific example, FIG. 22 illustrates a case where TCI status IDs corresponding to beams possible in candidate cells applicable to the present disclosure are indicated to each candidate cell. Referring to FIG. 22, a terminal (2210) can perform L1 RSRP measurements for one or more candidate cells (2230, 2240) for LTM operation. That is, the terminal (2210) can receive reference signals (e.g., SSB, CSI-RS) from one or more candidate cells (2230, 2240) and perform L1 RSRP measurements based thereon. Then, the terminal (2210) can transmit the L1 measurement report to the source cell (2220). Here, the terminal can transmit the measured L1 results to the source cell (2220) based on at least one of a periodic method and an event-based reporting method. As an example, the L1 results can be reported via at least one of PUCCH and PUSCH.

[0265] Referring to FIG. 22, candidate cell 1 (2230) and candidate cell 2 (2240) may be configured as LTM candidate cells. Here, the possible beams of candidate cell 1 (2230) may be SSB1, SSB3, and SSB6, and the possible beams of candidate cell 2 (2240) may be CSI-RS3 and CSI-RS20. Candidate cell 1 (2230) may be configured with SSB beams for measurement, and candidate cell 2 (2240) may be configured with CSI-RS beams for measurement. However, this is merely an example for convenience of explanation and is not limited thereto, and it may also be possible for a terminal to measure with a mixture of SSB beams and CSI-RS beams in a single candidate cell.

[0266] Afterward, the terminal (2210) may receive an RRC reconstruction message from the source cell (2220). The source cell (2220) may set a conditional LTM for the terminal based on the L1 measurement report reported by the terminal (2210), and may provide a list of corresponding TCI status IDs for candidate beams where the terminal evaluates the event and the event condition is satisfied. As a specific example, the source cell (2220) may instruct the terminal (2210) to provide a list of TCI status IDs for candidate cell 1 (2230) that includes TCI status IDs corresponding to SSB1, SSB3, and SSB6. As an example, if the terminal (2210) determines that SSB3 satisfies the condition based on the event evaluation procedure, the terminal (2210) may determine the validity of the CG occupancy using the TCI status ID associated with SSB3.

[0267] As another example, for candidate cell 2 (2240), the TCI status ID list may indicate TCI status IDs corresponding to CSI-RS 3 and CSI-RS 20. That is, the terminal (2210) can obtain the TCI status ID list for candidate cell 2 (2240) from the source cell (2220). Here, if the terminal (2210) determines that CSI-RS 20 satisfies the condition based on the event evaluation procedure, the terminal (2210) can determine whether the CG occupancy is valid using CSI-RS 20 and the TCI status ID.

[0268] That is, the source cell (2220) transmits the TCI state ID list information of candidate cells along with conditional LTM information in the RRC reconstruction message transmitted to the terminal (2210) based on the L1 measurement result, and the terminal (2210) can determine the validity of the CG occupancy with at least one selected beam and the associated TCI state ID based on the event evaluation condition.

[0269] FIG. 23 is a diagram illustrating a case where TCI status IDs corresponding to beams possible in candidate cells applicable to the present disclosure are indicated to each candidate cell. Referring to FIG. 23, a terminal (2310) can perform L1 RSRP measurements for one or more candidate cells (2330, 2340) for LTM operation. That is, the terminal (2310) can receive reference signals (e.g., SSB, CSI-RS) from one or more candidate cells (2330, 2340) and perform L1 RSRP measurements based thereon. Then, the terminal (2310) can transmit the L1 measurement report to the source cell (2320). Here, the terminal can transmit the measured L1 results to the source cell (2320) based on at least one of a periodic method and an event-based reporting method. As an example, the L1 results may be reported via at least one of PUCCH and PUSCH.

[0270] Referring to FIG. 23, candidate cell 1 (2330) and candidate cell 2 (2340) may be configured as LTM candidate cells. Here, the possible beams of candidate cell 1 (2330) may be SSB1, SSB3, and SSB6, and the possible beams of candidate cell 2 (2340) may be CSI-RS3 and CSI-RS20. Candidate cell 1 (2330) may be configured with SSB beams for measurement, and candidate cell 2 (2340) may be configured with CSI-RS beams for measurement. However, this is merely an example for convenience of explanation and is not limited thereto, and it may also be possible for a terminal to measure with a mixture of SSB beams and CSI-RS beams in a single candidate cell.

[0271] Afterward, the terminal (2310) may receive an RRC reconstruction message from the source cell (2320). The source cell (2320) may set a conditional LTM for the terminal based on the L1 measurement report reported by the terminal and may provide the terminal with a current TCI state ID for one or more candidate cells that the terminal evaluates event conditions. As a specific example, the current TCI state ID of candidate cell 1 (2330) and the current TCI state ID of candidate cell 2 (2340) may be included in the RRC reconstruction message and indicated to the terminal (2310). As a specific example, the TCI state ID for candidate cell 1 (2330) in the RRC reconstruction message may correspond to the TCI state ID corresponding to the beam with the strongest signal strength among SSB1, SSB3, and SSB6 based on the L1 measurement results reported by the terminal. If the terminal (2310) evaluates a possible beam for candidate cell 1 (2330) in an event evaluation procedure and the condition is satisfied, the terminal (2310) can determine that the CG occupancy with the beam associated with the indicated current TCI status ID is valid.

[0272] As another example, the TCI status ID for candidate cell 2 (2340) in the RRC reconstruction message may be the TCI status ID corresponding to the beam with the strongest signal strength among CSI-RS 3 and CSI-RS 20 based on the L1 measurement results reported by the terminal. If the terminal (2310) evaluates the possible beams for candidate cell 2 (2340) in the event evaluation procedure and the conditions are satisfied, the terminal (2310) may determine that the CG occupancy configured with the beam associated with the indicated current TCI status ID is valid. That is, the source cell (2320) may transmit conditional LTM configuration information and the current TCI status IDs of the candidate cells in the RRC reconstruction message transmitted to the terminal (2310) based on the L1 measurement results, and the terminal (2310) may determine the validity of the CG occupancy with at least one selected beam and the TCI status ID associated therewith based on the event evaluation conditions.

[0273] Here, the terminal (2310) can transmit the measured L1 result to the source cell (2320) based on at least one of a periodic method and an event-based reporting method. For example, the L1 result can be reported via at least one of PUCCH and PUSCH.

[0274]

[0275] Additionally, as an example, a procedure for updating and setting the TCI status of a candidate cell can be performed based on an L1 measurement report from a source cell. The source cell may receive L1 measurement results from a terminal at least once and, based on this, determine whether to set or change the TCI status ID for the candidate cell.

[0276] As a specific example, the source cell may receive L1 measurement results from the terminal one or more times and change the TCI state ID for the candidate cell based on these results. More specifically, the source cell may set the TCI state ID for the candidate cell to the terminal via at least one of RRC and MAC CE. Subsequently, the source cell may determine to update the TCI state ID for the candidate cell based on the new L1 measurement results, and the updated TCI state ID may be indicated to the terminal. Here, the source cell may indicate the current TCI state ID for one or more candidate cells to the terminal via the TCI state MAC CE based on the L1 measurement results.

[0277] FIG. 24 is a diagram illustrating a MAC CE for indicating the TCI status for one or more candidate cells applicable to the present disclosure. Referring to FIG. 24, the MAC CE format may include a candidate cell ID and a corresponding TCI status ID. The candidate cell ID and the TCI status ID may be paired and indicated within one octet, but are not limited thereto. For example, it may be possible for the candidate cell ID to be indicated in order, followed by the TCI status ID, and is not limited to a specific form. Also, for example, FIG. 24(a) may be a format for indicating the TCI status ID for a single candidate cell. On the other hand, the MAC CE format for indicating the TCI status ID for two or more candidate cells may be as in FIG. 24(b). Up to eight candidate cells may be considered within the LTM configuration. Therefore, when indicating the TCI status ID for two or more candidate cells, the MAC CE format may be up to eight octets. However, this is merely one example and is not limited thereto; it may have other octet sizes and is not limited to a specific form.

[0278] For example, up to 8 candidate cells for LTM can be set, so the code point of the activated TCI state can be indicated through a candidate cell ID indicated by 3 bits and a TCI state ID indicated by 3 bits, but is not limited to such an embodiment.

[0279]

[0280] FIG. 25 is a diagram illustrating the operation of a wireless user device applicable to the present disclosure. Referring to FIG. 25, the wireless user device may obtain LTM configuration information based on a conditional LTM from a source cell (S2510). For example, the LTM configuration information may include information about one or more candidate cells and event condition information for performing LTM. For example, the event condition information may be as shown in Table 15, but is not limited thereto. Subsequently, the wireless user device can perform uplink / downlink pre-synchronization with one or more candidate cells (S2520). Subsequently, the wireless user device can acquire reference signals from one or more candidate cells and perform measurements, and can check whether event conditions are satisfied based on the measurement results (S2530). For example, whether event conditions are satisfied can be checked based on L1 measurement results, and the wireless user device can complete the LTM procedure by transmitting an RRC reconstruction message to a target cell that satisfies the event conditions among one or more candidate cells (S2540). Here, the wireless user device can complete the LTM procedure by transmitting an RRC reconstruction message to the target cell through the TAC for each of one or more candidate cells acquired from the source cell. For example, the wireless user device can transmit a preamble to each of one or more candidate cells after receiving a PDCCH order for each of one or more candidate cells from the source cell. A source cell obtains a TAC from each of one or more candidate cells based on a preamble transmitted to each of one or more candidate cells by a wireless user device, and the wireless user device can obtain an LTM TAC MAC CE containing the TAC for each of one or more candidate cells from the source cell.

[0281] Additionally, the wireless user device may receive one or more TATs from the source cell via RRC signaling. For example, the wireless user device may receive multiple TATs via RRC signaling and be instructed to receive a TAT corresponding to the TAC via LTM TAC MAC CE.

[0282] Additionally, a configured grant (CG) for conditional LTM and a CG occasion based on the CG may be established in the wireless user device. For example, a CG occasion is associated with at least one reference signal, and the wireless user device may receive the reference signal from one or more candidate cells and perform a measurement. Based on the measurement, the wireless user device may check whether an event condition is satisfied and, based on whether the event condition is satisfied, check whether the CG occasion is valid.

[0283] Additionally, the wireless user device may complete the LTM procedure by transmitting an RRC reconstruction message through the earliest arriving CG occupation among the CG occupations associated with the reference signal satisfying the event condition. For example, the wireless user device transmits a measurement report for one or more candidate cells to a source cell based on at least one of periodic and event-based reporting, and receives conditional LTM information and one or more TCI status information related to the candidate cells from the source cell, wherein the TCI status information related to the one or more candidate cells may include a list of TCI status IDs for each of the candidate cells or the current TCI status ID.

[0284] FIG. 26 is a drawing showing a device configuration to which the present disclosure can be applied.

[0285] Referring to FIG. 26, the first device (2600) and the second device (2650) can communicate with each other. In this case, for example, the first device (2600) may be a base station device and the second device (2650) may be a terminal device. In another example, both the first device (2600) and the second device (2650) may be terminal devices. In yet another example, the first device (2600) and the second device (2650) may be satellite IAB nodes. That is, the first device (2600) and the second device (2650) may be devices that communicate with each other based on NR-based communication and are not limited to a specific form.

[0286] The first device (2600) may include a processor (2620), an antenna unit (2612), a transceiver (2614), and a memory (2616). The processor (2620) performs baseband-related signal processing and may include an upper layer processing unit (2626) and a physical layer processing unit (2640). The upper layer processing unit (2627) may process operations of the MAC (Medium Access Control) layer, the RRC (Radio Resource Control) layer, or higher upper layers. The physical layer processing unit (2640) may process operations of the physical (PHY) layer (e.g., uplink reception signal processing, downlink transmission signal processing). In addition to performing baseband-related signal processing, the processor (2620) may also control the overall operation of the first device (2600). The antenna section (2612) may include one or more physical antennas, and if it includes multiple antennas, it may support MIMO (Multiple Input Multiple Output) transmission and reception. Additionally, it may support beamforming. The memory (2616) may store information processed by the processor (2620), software related to the operation of the first device (2600), an operating system, an application, etc., and may include components such as a buffer. The processor (2620) of the first device (2600) may be configured to implement the operation of the first device in the embodiments described in the present invention.

[0287] The second device (2650) may include a processor (2670), an antenna unit (2662), a transceiver (2664), and a memory (2666). For example, in the present invention, the second device (2650) may communicate with the first device (2600). The processor (2670) performs baseband-related signal processing and may include an upper layer processing unit (2680) and a physical layer processing unit (2690). The upper layer processing unit (2680) may process operations of the MAC layer, RRC layer, or higher upper layers. The physical layer processing unit (2690) may process operations of the PHY layer (e.g., downlink reception signal processing, uplink transmission signal processing, sidelink signal processing). In addition to performing baseband-related signal processing, the processor (2670) may also control the overall operation of the second device (2650). The antenna section (2662) may include one or more physical antennas, and if it includes multiple antennas, it may support MIMO transmission and reception. Additionally, it may support beamforming. The memory (2666) may store information processed by the processor (2670), software related to the operation of the second device (2650), operating systems, applications, etc., and may include components such as buffers. The second device (2650) according to an example of the present invention may be associated with a vehicle. For example, the second device (2650) may be integrated into the vehicle, located in the vehicle, or located on the vehicle. Additionally, the second device (2650) according to the present invention may be the vehicle itself. Furthermore, the second device (2650) according to the present invention may be at least one of a wearable terminal, an AV / VR, an IoT terminal, a robot terminal, or a public safety terminal.The terminal device (2650) to which the present invention is applicable may include any type of communication device that supports interactive services utilizing sidelinks for services such as internet access, service execution, navigation, real-time information, autonomous driving, safety and risk diagnosis. Additionally, it may include any type of communication device that acts as an AR / VR device capable of sidelink operation or a sensor to perform relay operations.

[0288] Here, the vehicle / terminal to which the present invention is applied may include an autonomous vehicle / terminal, a semi-autonomous vehicle / terminal, a non-autonomous vehicle / terminal, etc. Meanwhile, although the second device (2650) according to one example of the present invention is described as being associated with a vehicle, one or more of the UEs may not be associated with a vehicle. This is an example, and the application of the present invention should not be interpreted as being limited to the example described. In addition, the second device (2650) according to one example of the present invention may include various types of communication devices capable of performing cooperation to support interactive services utilizing sidelinks. That is, the second device (2650) may be utilized not only when it directly supports interactive services utilizing sidelinks, but also as a cooperation device to support interactive services utilizing sidelinks.

[0289] Here, for example, a terminal device (second device, 2650) may obtain LTM configuration information based on conditional LTM from a source cell. For example, the LTM configuration information may include information about one or more candidate cells and event condition information for performing LTM. For example, the event condition information may be as shown in Table 15, but is not limited thereto. Subsequently, the terminal device (2650) may perform uplink / downlink pre-synchronization with one or more candidate cells. Subsequently, the terminal device (2650) may obtain reference signals from one or more candidate cells and perform measurements, and may check whether the event condition is satisfied based on the measurement results. For example, whether the event condition is satisfied may be checked based on the L1 measurement results, and the terminal device (2650) may complete the LTM procedure by transmitting an RRC reconstruction message to a target cell among one or more candidate cells that satisfies the event condition. Here, the terminal device (2650) can complete the LTM procedure by transmitting an RRC reconstruction message to the target cell through the TAC for each of one or more candidate cells obtained from the source cell. For example, the terminal device (2650) can transmit a preamble to each of one or more candidate cells after receiving a PDCCH order for each of one or more candidate cells from the source cell. The source cell obtains a TAC from each of one or more candidate cells based on the preamble transmitted to each of one or more candidate cells by the terminal device (2650), and the terminal device (2650) can obtain an LTM TAC MAC CE containing the TAC for each of one or more candidate cells from the source cell. Additionally, the terminal device (2650) can receive one or more TATs from the source cell via RRC signaling. For example, the terminal device (2650) can receive multiple TATs via RRC signaling and receive instructions for the TAT corresponding to the TAC through the LTM TAC MAC CE.Additionally, the terminal device (2650) may have a configured grant (CG) for conditional LTM and a CG occasion based on the CG. For example, the CG occasion may be associated with at least one reference signal, and the terminal device (2650) may receive the reference signal from one or more candidate cells and perform a measurement. The terminal device (2650) may check whether an event condition is satisfied based on the measurement and check whether the CG occasion is valid based on whether the event condition is satisfied. Additionally, the terminal device (2650) may complete the LTM procedure by transmitting an RRC reconstruction message through the earliest arriving CG occasion among the CG occasions associated with the reference signal satisfying the event condition. For example, a terminal device (2650) transmits a measurement report for one or more candidate cells to a source cell based on at least one of periodic and event-based reporting, and receives conditional LTM information and TCI status information related to one or more candidate cells from the source cell, wherein the TCI status information related to one or more candidate cells may include a list of TCI status IDs for each of the candidate cells or a current TCI status ID.

[0290] In addition, various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, it may be implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), general processors, controllers, microcontrollers, microprocessors, etc.

[0291] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating system, application, firmware, program, etc.) that enable an operation according to a method of various embodiments to be executed on a device or computer, and a non-transitory computer-readable medium on which such software or instructions, etc. are stored and executable on a device or computer.

[0292] The various embodiments of the present disclosure are not intended to list all possible combinations but to describe representative aspects of the present disclosure, and the matters described in the various embodiments may be applied independently or in combination of two or more.

[0293]

[0294] The above-mentioned matters may also be applied to other systems.

Claims

1. In a wireless user device, Wireless transceiver; One or more processors; and A memory that stores instructions for the wireless device when executed by one or more of the above processes, The operation of the above wireless device is: LTM configuration information is obtained from a source cell based on conditional LTM (L1 / L2 layer triggered mobility), wherein the LTM configuration information includes information on one or more candidate cells and event condition information for performing LTM. The wireless user device performs uplink / downlink pre-synchronization with the one or more candidate cells, and The wireless user device acquires a reference signal from one or more candidate cells and performs a measurement, and checks whether an event condition is satisfied based on the measurement result. A wireless user device that completes the LTM procedure by transmitting a radio resource control (RRC) reconstruction message to a target cell satisfying the event condition among the above one or more candidate cells, wherein the wireless user device completes the LTM procedure by transmitting the RRC reconstruction message to the target cell through a timing advance command (TAC) for each of the one or more candidate cells obtained from the source cell.

2. In Paragraph 1, The wireless user device receives a PDCCH (physical downlink control channel) order for each of one or more candidate cells from the source cell and then transmits a preamble to each of the one or more candidate cells, wherein the source cell obtains a TAC from each of the one or more candidate cells based on the preamble transmitted to each of the one or more candidate cells by the wireless user device. A wireless user device that obtains an LTM TAC MAC CE (medium access control element) from a source cell, the LTM TAC MAC CE including a TAC for each of the one or more candidate cells.

3. In Paragraph 2, The above wireless user device receives one or more TATs (time alignment timers) from the source cell via RRC signaling, and A wireless user device in which the above LTM TAC MAC CE further includes a TAT (time alignment timer) for the TAC for each of the one or more candidate cells.

4. In Paragraph 1, The wireless user device has a configured grant (CG) for the conditional LTM and a CG occasion established based on the CG, wherein the CG occasion is associated with at least one reference signal, and A wireless user device that receives a reference signal from one or more candidate cells to perform a measurement, checks whether the event condition is satisfied based on the measurement, and checks whether the CG occupancy is valid based on whether the event condition is satisfied.

5. In Paragraph 4, A wireless user device that completes the LTM procedure by transmitting the RRC reconstruction message through the earliest arriving CG occupation among the CG occupations associated with the reference signal satisfying the event condition.

6. In Paragraph 4, The wireless user device transmits a measurement report for the one or more candidate cells to the source cell based on at least one of periodic and event-based reporting, and Receive conditional LTM information and one or more TCI (transmission configuration indicator) status information related to candidate cells from the source cell, A wireless user device having TCI status information associated with one or more of the above candidate cells, comprising a list of TCI status IDs for each of the candidate cells or a current TCI status ID.

7. In a method of operating a wireless user device, A step of obtaining LTM configuration information from a source cell based on conditional LTM (L1 / L2 layer triggered mobility), wherein the LTM configuration information includes information on one or more candidate cells and event condition information for performing LTM; A step of performing uplink / downlink pre-synchronization with one or more candidate cells; The wireless user device acquires a reference signal from one or more candidate cells, performs a measurement, and checks whether an event condition is satisfied based on the measurement result; A method of operation of a wireless user device, comprising the step of completing an LTM procedure by transmitting a radio resource control (RRC) reconfiguration message to a target cell satisfying the event condition among one or more candidate cells, wherein the wireless user device completes the LTM procedure by transmitting the RRC reconfiguration message to the target cell through a timing advance command (TAC) for each of the one or more candidate cells obtained from a source cell.

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