Apparatus and method for inter-CU LTM coordination between MN and sn in wireless communication system

Abstract

The present disclosure relates to a wireless communication system. Specifically, the present disclosure relates to an apparatus and method for coordination between a master node (MN) and a secondary node (SN) to support an inter-centralized unit (CU) layer 1 / layer 2-triggered mobility (LTM) operation in a wireless communication system where dual connectivity is configured.

Description

Device and method for coordinating inter-CU LTM between MN and SN in a wireless communication system

[0001] The present disclosure relates to a wireless communication system. Specifically, the present disclosure relates to a device and method for coordination between a master node (MN) and a secondary node (SN) to support LTM (Layer 1 / Layer 2-triggered Mobility) operation between centralized units (CUs) in a wireless communication system with dual connectivity.

[0002]

[0003] The 3rd Generation Partnership Project (3GPP) Rel-18 standard specifies a new mobility solution called LTM (L1 / L2-Triggered Mobility). LTM aims to reduce latency, overhead, and service interruption during cell switching, and includes technologies such as early DL / UL synchronization before cell switching and L1 layer measurement-based handover. However, in Rel-18, LTM was limited to scenarios where movement occurs within a single Centralized Unit (CU) (Intra-CU).

[0004] Subsequently, Rel-19 set the goal of extending LTM technology to inter-CU mobility. In particular, in a dual connectivity (DC) environment where a terminal is connected to both a master node (MN) and a secondary node (SN) at the same time, a new constraint was introduced: inter-CU LTM cannot be configured simultaneously on both the MN and the SN. In Rel-18, MN and SN could operate independently without coordination only for intra-CU LTM, but due to the new constraints in Rel-19, a clear coordination procedure is now essential to prevent collisions between MN and SN.

[0005] The need for this coordination is further amplified by the inherent "continuous" nature of LTM technology. While traditional handovers are a one-time operation to a single target cell, LTM enables continuous movement to multiple candidate cells with a single setup. Therefore, LTM does not terminate automatically and requires an explicit network release command. This creates uncertainty: while one node (e.g., MN) is executing inter-MN LTM, the other node (SN) has no way of knowing when the procedure will end, and thus cannot determine when it can initiate its own LTM procedure.

[0006] Consequently, LTM termination notification from one node to another is crucial to prevent unnecessary requests and rejections. In particular, when an inter-SN LTM terminates, the MN must clear the associated resources of other candidate SNs, so termination notification from the SN is essential. Considering this context, this specification proposes specific coordination mechanisms between the MN and the SN to prevent simultaneous establishment of inter-CU LTMs on both sides in a dual-connectivity environment.

[0007]

[0008] In order to solve the above-described problem, the present disclosure provides a device and method for coordination between a master node (MN) and a secondary node (SN) to support LTM (Layer1 / Layer2-triggered Mobility) operation between Centralized Units (CUs) in a wireless communication system with dual connectivity established.

[0009] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0010]

[0011] According to various embodiments of the present disclosure, a method is provided, performed by a first node, comprising: transmitting, to a second node, a first message not allowing configuration of inter-secondary node layer1 / layer2-triggered mobility (Inter-SN LTM) based on initiation of inter-master node layer1 / layer2-triggered mobility (Inter-MN LTM); and transmitting, to the second node, a second message allowing configuration of the inter-SN LTM based on termination of the inter-MN LTM.

[0012] According to various embodiments of the present disclosure, a method is provided, performed by a second node, comprising: receiving a first message from a first node, based on initiation of inter-master node layer1 / layer2-triggered mobility (Inter-MN LTM), which does not allow configuration of inter-secondary node layer1 / layer2-triggered mobility (Inter-SN LTM); and receiving a second message from the first node, based on termination of the inter-MN LTM, which allows configuration of the inter-SN LTM.

[0013] According to various embodiments of the present disclosure, a first node is provided, comprising: a transceiver; at least one processor; and at least one memory operably connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations, wherein the operations include all steps of a method performed by the first node according to various embodiments of the present disclosure.

[0014] According to various embodiments of the present disclosure, a second node is provided, comprising: a transceiver; at least one processor; and at least one memory operably connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations, wherein the operations include all steps of a method performed by the second node according to various embodiments of the present disclosure.

[0015] According to various embodiments of the present disclosure, a control device for controlling a first node in a wireless communication system is provided, the control device including at least one processor and at least one memory operably connected to the at least one processor, wherein the at least one memory stores instructions for performing operations based on being executed by the at least one processor, the operations including all steps of a method performed by the first node according to various embodiments of the present disclosure.

[0016] According to various embodiments of the present disclosure, a control device for controlling a second node in a wireless communication system is provided, the control device including at least one processor and at least one memory operably connected to the at least one processor, wherein the at least one memory stores instructions for performing operations based on being executed by the at least one processor, the operations including all steps of a method performed by the second node according to various embodiments of the present disclosure.

[0017] According to various embodiments of the present disclosure, there is provided one or more non-transitory computer-readable media storing one or more instructions, wherein the one or more instructions, when executed by one or more processors, perform operations, the operations including all steps of a method performed by a first node according to various embodiments of the present disclosure.

[0018] According to various embodiments of the present disclosure, there is provided one or more non-transitory computer-readable media storing one or more instructions, wherein the one or more instructions, when executed by one or more processors, perform operations, the operations including all steps of a method performed by a second node according to various embodiments of the present disclosure.

[0019]

[0020] In order to solve the above-described problem, the present disclosure may provide a device and method for coordination between a master node (MN) and a secondary node (SN) to support LTM (Layer1 / Layer2-triggered Mobility) operation between centralized units (CUs) in a wireless communication system with dual connectivity established.

[0021]

[0022] The accompanying drawings are intended to aid in understanding the present disclosure and, together with detailed descriptions, may provide embodiments of the present disclosure. However, the technical features of the present disclosure are not limited to specific drawings, and the features disclosed in each drawing may be combined with each other to form new embodiments. Reference numerals in each drawing may indicate structural elements.

[0023] FIG. 1 is a diagram illustrating an example of physical channels used in a system applicable to the present disclosure and a general signal transmission method using the same.

[0024] FIG. 2 is a diagram illustrating an example of a wireless frame structure used in a system applicable to the present disclosure.

[0025] FIG. 3 is a drawing illustrating an example of a slot structure used in a system applicable to the present disclosure.

[0026] FIG. 4 is a diagram illustrating an example of a slot structure of a wireless frame used in a system applicable to the present disclosure.

[0027] FIG. 5 is a diagram illustrating an example of a process for notifying an SN of an inter-MN LTM in a system applicable to the present disclosure.

[0028] FIG. 6 is a diagram illustrating an example of a process for notifying an SN of an inter-MN LTM in a system applicable to the present disclosure.

[0029] FIG. 7 is a diagram illustrating an example of a process for notifying an MN of inter-SN LTM termination in a system applicable to the present disclosure.

[0030] FIG. 8 is a diagram illustrating an example of a process for notifying an MN of inter-SN LTM termination in a system applicable to the present disclosure.

[0031] FIG. 9 is a diagram illustrating an example of the operation process of the first node in a system applicable to the present disclosure.

[0032] FIG. 10 is a diagram illustrating an example of the operation process of a second node in a system applicable to the present disclosure.

[0033] FIG. 11 is a diagram illustrating an example of the structure of a first node and a second node in a system applicable to the present disclosure.

[0034]

[0035] In various embodiments of the present disclosure, “A or B” may mean “only A,” “only B,” or “both A and B.” In other words, in various embodiments of the present disclosure, “A or B” may be interpreted as “A and / or B.” For example, in various embodiments of the present disclosure, “A, B or C” may mean “only A,” “only B,” “only C,” or “any combination of A, B and C.”

[0036] In various embodiments of the present disclosure, a slash ( / ) or a comma may mean "and / or." For example, "A / B" may mean "A and / or B." Accordingly, "A / B" may mean "only A," "only B," or "both A and B." For example, "A, B, C" may mean "A, B, or C."

[0037] In various embodiments of the present disclosure, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Furthermore, in various embodiments of the present disclosure, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted as equivalent to “at least one of A and B.”

[0038] Additionally, in various embodiments of the present disclosure, “at least one of A, B and C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C.”

[0039] Additionally, parentheses used in various embodiments of the present disclosure may mean "for example." Specifically, when indicated as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information." In other words, "control information" in various embodiments of the present disclosure is not limited to "PDCCH", and "PDDCH" may be proposed as an example of "control information." Furthermore, even when indicated as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information."

[0040] Technical features individually described in a single drawing in various embodiments of the present disclosure may be implemented individually or simultaneously.

[0041]

[0042] Common signal transmission methods in 3GPP

[0043] Physical channels and general signal transmission

[0044] FIG. 1 is a diagram illustrating an example of physical channels used in a system applicable to the present disclosure and a general signal transmission method using these channels. Specifically, FIG. 1 illustrates physical channels used in a 3GPP system and general signal transmission.

[0045] Figure 1 illustrates the physical channels and typical signal transmission used in the 3GPP system. In a wireless communication system, a terminal receives information from a base station via the downlink (DL), and the terminal transmits information to the base station via the uplink (UL). The information transmitted and received between the base station and the terminal includes data and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and receive.

[0046] When a terminal is powered on again from a powered-off state or newly enters a cell, it performs an initial cell search operation, such as synchronizing with the base station (S11). To this end, the terminal receives the PSCH (Primary Synchronization Channel) and SSCH (Secondary Synchronization Channel) from the base station to synchronize with the base station and obtain information such as the cell ID (cell identity). In addition, the terminal can obtain broadcast information within the cell by receiving the PBCH (Physical Broadcast Channel) from the base station. In addition, the terminal can receive the DL RS (Downlink Reference Signal) during the initial cell search phase to check the downlink channel status.

[0047] A terminal that has completed initial cell search can obtain more specific system information by receiving a PDCCH (Physical Downlink Control Channel) and a corresponding PDSCH (Physical Downlink Control Channel) (S12).

[0048] Thereafter, the terminal may perform a random access procedure to complete connection to the base station (S13-S16). Specifically, the terminal may transmit a preamble via a physical random access channel (PRACH) (S13) and receive a random access response (RAR) for the preamble via a physical downlink control channel (PDCCH) and a corresponding PDSCH (S14). Thereafter, the terminal may transmit a physical uplink shared channel (PUSCH) using scheduling information in the RAR (S15) and perform a contention resolution procedure such as a PDCCH and a corresponding PDSCH (S16).

[0049] A terminal that has performed the above-described procedure can then perform PDCCH / PDSCH reception (S17) and PUSCH / PUCCH (Physical Uplink Control Channel) transmission (S18) as general uplink / downlink signal transmission procedures. Control information that the terminal transmits to the base station is referred to as UCI (Uplink Control Information). UCI includes HARQ ACK / NACK (Hybrid Automatic Repeat and reQuest Acknowledgement / Negative-ACK), SR (Scheduling Request), CSI (Channel State Information), etc. CSI includes CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indication), etc. UCI is generally transmitted through PUCCH, but can be transmitted through PUSCH when control information and data must be transmitted simultaneously. In addition, the terminal can aperiodically transmit UCI through PUSCH according to a request / instruction of the network.

[0050]

[0051] OFDM (Orthogonal Frequency Division Multiplexing) Numerology

[0052] The new RAT system uses OFDM transmission scheme or a similar transmission scheme. The new RAT system may follow OFDM parameters different from those of LTE. Alternatively, the new RAT system may follow the existing LTE / LTE-A numerology but have a larger system bandwidth (e.g., 100 MHz). Alternatively, a single cell may support multiple numerologies. That is, UEs operating under different numerologies can coexist within a single cell.

[0053]

[0054] Radio frame structure

[0055] FIG. 2 is a diagram illustrating an example of the structure of a wireless frame used in a system applicable to the present disclosure.

[0056] In NR, uplink and downlink transmissions are organized into frames. A radio frame is 10 ms long and is defined by two 5 ms half-frames (HF). Each half-frame is defined by five 1 ms subframes (SF). A subframe is divided into one or more slots, and the number of slots in a subframe depends on the subcarrier spacing (SCS). Each slot contains 12 or 14 OFDM(A) symbols, depending on the cyclic prefix (CP). When a regular CP is used, each slot contains 14 symbols. When an extended CP is used, each slot contains 12 symbols. Here, the symbols can include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or DFT-s-OFDM symbols).

[0057] Table 1 illustrates that when CP is normally used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary depending on the SCS.

[0058] SCS (15*2^u)N slot symb N frame,u slot N subframe,u slot 15KHz (u=0)1410130KHz (u=1)1420260KHz (u=2)14404120KHz (u=3)14808240KHz (u=4)1416016

[0059] N slot symb is the number of symbols in the slot. N frame,u slotis the number of slots in the frame. N subframe,u slot is the number of slots within a subframe.

[0060]

[0061] Table 2 illustrates that when extended CP is used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary depending on the SCS.

[0062] SCS (15*2^u)N slot symb N frame,u slot N subframe,u slot 60KHz (u=2)12404

[0063] NR supports multiple numerologies (or subcarrier spacings (SCS)) to support various 5G services. For example, an SCS of 15 kHz supports wide areas in traditional cellular bands; an SCS of 30 kHz / 60 kHz supports dense urban areas, lower latency, and wider carrier bandwidth; and an SCS of 60 kHz or higher supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0064] The NR frequency band can be defined by two types of frequency ranges (FR1, FR2). The numerical values ​​of the frequency ranges can be changed, and for example, the two types of frequency ranges (FR1, FR2) can be as shown in Table 3 below. For convenience of explanation, among the frequency ranges used in the NR system, FR1 can mean the "sub 6 GHz range", and FR2 can mean the "above 6 GHz range" and can be called millimeter wave (mmW).

[0065] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0066] As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a band from 410 MHz to 7125 MHz, as shown in Table 4 below. That is, FR1 may include a frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, such as for vehicular communications (e.g., autonomous driving).

[0067] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0068] In an NR system, OFDM(A) numerologies (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., SF, slot, or TTI) (conveniently referred to as TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells.

[0069]

[0070] FIG. 3 is a drawing illustrating an example of a slot structure used in a system applicable to the present disclosure.

[0071] A slot contains multiple symbols in the time domain. For example, a slot contains 7 symbols for a regular CP, but 6 symbols for an extended CP. A carrier contains multiple subcarriers in the frequency domain. A Resource Block (RB) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A Bandwidth Part (BWP) is defined as multiple consecutive (P)RBs in the frequency domain, and can correspond to a single numerology (e.g., SCS, CP length, etc.). A carrier can contain up to N (e.g., 5) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for a single terminal. Each element in the resource grid is referred to as a Resource Element (RE), to which one complex symbol can be mapped.

[0072]

[0073] FIG. 4 is a diagram illustrating an example of a slot structure of a wireless frame used in a system applicable to the present disclosure.

[0074] Fig. 4 is an exemplary system, illustrating the slot structure of a frame of an NR system.

[0075] The frame structure of NR is characterized by a self-contained structure in which a DL control channel, DL or UL data, and UL control channel can all be included in a single slot unit, as shown in the example of FIG. 4. At this time, DL data scheduling information, UL data scheduling information, etc. can be transmitted in the DL control channel, and ACK / NACK information for DL ​​data, CSI information (modulation and coding scheme information, MIMO transmission-related information, etc.), scheduling requests, etc. can be transmitted in the UL control channel. In FIG. 4, a time gap for DL-to-UL or UL-to-DL switching may exist between the control region and the data region. In addition, some of DL control / DL data / UL data / UL control may not be configured within a single slot. Or, the order of each channel configuring a single slot may be different. (For example, DL control / DL data / UL control / UL data or UL control / UL data / DL control / DL data, etc.)

[0076]

[0077] The present disclosure relates to methods for Inter-CU (Centralized Unit) LTM (L1L2-triggered Mobility) coordination between MN (master node) and SN (secondary node).

[0078]

[0079] Technical terms used in this disclosure

[0080] - S-MN: The radio access node currently serving the UE's MCG (i.e. source master node).

[0081] - S-MN-CU: CU (centralized unit) of S-MN.

[0082] - S-SN: The radio access node currently serving the UE's SCG (i.e. source secondary node) and connected with the UE's S-MN by X2 or Xn interface.

[0083] - S-SN-CU: CU (centralized unit) of S-SN.

[0084] - C-MN-CU: CU of a candidate MN and connected with S-MN by X2 or Xn interface.

[0085] - C-SN-CU: CU of a candidate SN and connected with S-MN by X2 or Xn interface.

[0086]

[0087] Description of background technology

[0088] Rel-18 specified a new type of mobility solution called LTM (L1 / L2 Triggered Mobility) to reduce late latency, overhead, and interruption time during serving cell changes. To achieve fast serving cell changes, early DL / UL synchronizations before cell switch and HO based on L1 measurement (and triggered by MAC CE) were specified for LTM.

[0089] In Rel-18, the scenarios considered in LTM have been limited to intra-CU case only, i.e., serving cell change within a single CU (centralized unit). In Rel-19, a new WI has been approved for NR mobility enhancement phase 4 [1: 3GPP Draft RP-241515, Revised Work Item: NR mobility enhancements Phase 4, Apple Inc, China Telecom] to specify inter-CU LTM:

[0090]

[0091] 4.1 Objective of SI or Core part WI or Testing part WI

[0092] (1) Specify support for inter-CU Layer1 / Layer 2 Triggered Mobility (LTM) [RAN2, RAN3]

[0093] (1-1) Prioritize the case when CU is acting as MN when DC is not configured.

[0094] (1-2) When DC is configured, inter-CU LTM can be configured in either the MN or the SN, but not both at the same time. In such cases:

[0095] (1-2-1) As a secondary priority, it supports the case where the CU is acting as the SN and the MN is unchanged.

[0096] (1-2-2) As a secondary priority, it supports the case where the CU is acting as an MN and the SN is unchanged or the SN is released.

[0097] (1-3) Specify support for subsequent LTM mobility procedures aimed at avoiding RRC configuration between cell switches as per Rel-18 LTM.

[0098] (1-3-1) Coordination with SA3 is needed with respect to security key handling.

[0099] (1-4) Note: The Rel. 18 intra-CU LTM procedure is considered as a baseline for adding inter-CU support.

[0100]

[0101] (2) Measurement-related enhancements for supporting LTM: [RAN2, RAN1]

[0102] (2-1) Measurement-related enhancements are applicable to intra-CU MCG / SCG LTM and inter-CU MCG / SCG LTM.

[0103] (2-2) Specify necessary components to support event triggered L1 measurement reporting [RAN2, RAN1]

[0104] (2-2-1) RAN1 and RAN2 independently progress on the event-triggered measurement objectives of their respective MIMO and mobility enhancement WIs. RAN#105 reviews the progress to determine if any modifications to objectives are required to avoid / manage any overlap in the work.

[0105] (2-3) Specify support for CSI-RS measurements for LTM procedures and enable CSI-RS-based beam management and / or other necessary physical layer operations on candidate cells before LTM [RAN1].

[0106]

[0107] (3) Specify support of conditional LTM [RAN2, RAN3, RAN1]

[0108] (3-1) Specify UE evaluated conditions for triggering LTM

[0109] (3-2) Aim to support conditional LTM including subsequent LTM

[0110] (3-3) Prioritize intra-CU LTM

[0111] (3-4) Establish a checkpoint for reviewing objectives at RAN#105. RAN WG work will not begin before this checkpoint.

[0112]

[0113] (4) Specify RRM requirements related to the above objectives as necessary [RAN4]

[0114]

[0115] The first objective is to extend the Rel-18 Intra-CU LTM mechanisms to the case of Inter-CU in non-DC (Dual Connectivity) scenarios. However, when DC is configured, additional work is needed to support Inter-CU LTM across MNs and SNs, respectively, as captured in the second objective: support Inter-SN-CU LTM (MN unchanged) and Inter-MN-CU LTM (SN unchanged or released).

[0116] When DC was established in Rel-18, independent "intra-CU" LTM operation from the MN or SN was allowed for their respective cells. The RRC signaling specified in Rel-18 allowed the network to establish LTM across the MCG and SCG, as long as it did not cause the UE to change PCell and PSCell simultaneously. Given that Rel-18 LTM was limited to "intra-CU" mobility, the serving MN-CU or serving SN-CU could independently determine the LTM for their respective PCell or PSCell for the UE without any coordination with each other. (In Rel-18, when DC is configured, independent "intra-CU" LTM operations from either MN or SN were allowed for their respective cells. The RRC signaling specified in Rel-18 allowed NW to configure LTM over MCG and over SCG, as long as it does not incur simultaneous PCell and PSCell changes to the UE. Given that Rel-18 LTM was limited to "Intra-CU" mobility, the serving MN-CU or the serving SN-CU was able to independently decide LTM over their respective PCells or PSCells for a UE, without having to coordinate with each other.)

[0117] However, in Rel-19, such independent behavior is restricted when Inter-CU LTM involves MN or SN. As described in the second goal of [1], Inter-CU LTM should not be established simultaneously in both MN and SN for a UE. Consequently, some coordination between MN and SN is required to prevent simultaneous LTM establishment in both MCG and SCG in Rel-19 Inter-CU LTM scenarios. For example, when Inter-MN LTM (or Inter-SN LTM) is prepared and established for a UE, the other party, i.e. SN (or MN), needs to be aware of that fact so that it does not initiate Inter-SN LTM (or Inter-MN LTM). (In Rel-19, however, such independent operations become limited when Inter-CU LTM is involved in MN or SN. As captured in the second objective in [1], Inter-CU LTM shall not be configured in both MN and SN at the same time for a UE. As a result, some coordination between MN and SN is necessary to prevent simultaneous LTM configuration in both MCG and SCG in Rel-19 Inter-CU LTM scenarios. For example, when Inter-MN LTM (or Inter-SN LTM) is being prepared and configured to the UE, the other peer, ie SN (or MN) needs to know such so that it does not initiate Inter-SN LTM (or Inter-MN LTM).)

[0118] Moreover, unlike traditional HO or conditional mobility mechanisms, LTM aims for continuous cell switching based on a single configuration with the UE. Once LTM is established, switching the UE's serving cell across (prepared) candidate cells does not require any intermediate RRC reconfiguration efforts from the network. In the past, HO was designed for one-time executions toward a specific target cell. Conditional mobility, in contrast to legacy HO, followed the same principle: even if multiple candidate cells were prepared, the RRC configuration was automatically released upon the UE's successful transition to one of the configured candidate cells. The only exception was Conditional PSCell Addition and Change (CPAC), which was extended in Rel-18 in a "subsequent" manner (so-called "subsequent CPAC") to allow continuous PSCell switching based on a single RRC configuration from the network (rather than automatic release upon successful transition). (Moreover, unlike traditional HO or conditional mobility mechanisms, LTM is aiming for consecutive cell switch based on a single configuration with the UE. Once LTM is configured, the UE's serving cell switch across the (prepared) candidate cells does not require NW's RRC reconfiguration efforts in the middle. In the past, HO was designed for one-time execution only, toward "a" specific target cell.The conditional mobility, although multiple candidate cells are prepared as opposed to the legacy HO, still followed the same principle such that its RRC configuration was auto-released upon the UE's successful execution to one of the configured candidate cells. Only exception was on CPAC (conditional PSCell addition & change), for which was extended in a "subsequent" fashion in Rel-18 (so, called "subsequent CPAC"), thereby allowing consecutive PSCell switches based on a single RRC configuration from NW (rather than automatic configuration release upon successful execution).).

[0119] Due to this "continuous" nature, termination of an LTM requires an explicit RRC reconfiguration by the network (e.g., sending an RRC Reset to release the LTM from the UE, or sending a legacy HO CMD to overlay it). For our scenario of interest in Rel-19, where DC is established, the above means that once an Inter-MN LTM (or Inter-SN LTM) is established, its termination (or release of the LTM from the UE) is decided / set by the responsible MN (or SN) - the timing is up to that responsible node. The other party, i.e. the SN (or MN), cannot know when it will be able to start preparing its Inter-CU LTM. Consequently, the notification of Inter-CU LTM termination from one node to another is very important, otherwise unnecessary Inter-CU LTM initiations / rejections will occur between the MN and the SN. However, in fact, such notification is essential especially in the case of Inter-SN LTM, as when the current serving SN decides to terminate Inter-SN LTM for the UE, it is the MN that has to clean up other SNs prepared for Inter-SN LTM. (Due to such "consecutive" nature, termination of LTM requires NW's explicit RRC reconfiguration (e.g. sending RRC reconfiguration to release LTM configuration from the UE, or sending the legacy HO CMD to overwrite).With respect to our scenario of interest in Rel-19 when DC is configured, the above means that, once Inter-MN LTM (or Inter-SN LTM) is configured, its termination (or LTM configuration release from the UE) is decided / configured by the responsible MN (or SN) - timing is left up to that responsible node. The other peer, i.e. SN (or MN) has no idea when it could start preparing its own Inter-CU LTM. As a result, some notification of Inter-CU LTM termination from one node to the other would be critical, otherwise unnecessary Inter-CU LTM initiation / rejection between MN and SN occurs. But in fact, such notification is essential, especially for the case of Inter-SN LTM, where it is the MN who should clean up the other SNs prepared for Inter-SN LTM when the current serving SN decides the termination of Inter-SN LTM for the UE.).

[0120] Considering the above aspects, in this disclosure, we propose several mechanisms between MN and SN to ensure that Inter-CU LTM does not get configured to the UE both in MN and SN at the same time for Rel-19 cases of Inter-SN-CU LTM (MN unchanged) and Inter-MN-CU LTM (SN unchanged).

[0121]

[0122] [1] RP-241515, Revised Work Item: NR mobility enhancements Phase 4, Apple Inc, China Telecom

[0123]

[0124] Composition and Method of the Invention

[0125] In this disclosure, '()' can be interpreted as both excluding the content within () and including the content within the parentheses.

[0126] In this disclosure, ' / ' may mean including all of the contents separated by / (and) or including only some of the contents separated by / (or).

[0127] Meanwhile, supporting Ambient IoT in 4G / 5G / 6G communication systems requires determining data encoding and modulation methods that take into account requirements different from conventional UHF passive RFID, device types, (spectrum) deployment scenarios, connectivity topologies, design targets, and functions. Furthermore, coexistence with efficient 4G / 5G / 6G communication systems must also be considered.

[0128] The present invention proposes a data encoding method, a modulation method, and a method of transmitting modulation symbols generated for Ambient IoT communication by mapping them to an OFDM-based waveform for coexistence with efficient 4G / 5G / 6G communication systems, taking into account the points mentioned above.

[0129]

[0130] Embodiment 1: Inter-MN LTM notification to SN

[0131] When DC is configured for a UE, upon the source MN (S-MN) initiates the Inter-MN LTM preparation with the other candidate MN(s) (C-MN) while the SN remains unchanged,

[0132] (1) The initiation of Inter-MN LTM for the UE may be notified to the SN through any other involved MN during the Inter-MN LTM preparation procedure.

[0133] (2) Alternatively, the S-MN may directly notify the SN of the UE's Inter-MN LTM preparation before or during the Inter-MN LTM preparation procedure.

[0134] (3) The SN that is notified of Inter-MN LTM for the UE does not initiate the Inter-SN LTM procedure for the UE to avoid simultaneous Inter-CU LTM configuration in both MCG and SCG of the UE.

[0135]

[0136] After Inter-MN LTM is successfully prepared and configured to the UE (with SN unchanged), once the current serving MN (either S-MN or one of C-MN(s) that is currently serving the UE) decides to release the Inter-MN LTM for the UE,

[0137] (1) The current serving MN may directly notify the SN of the termination of the Inter-MN LTM.

[0138] (2) Alternatively, the current serving MN may cancel the Inter-MN LTM with other involved MN(s) for which the contacted MN may notify the SN of the termination of the Inter-MN LTM by releasing the SN for the UE from this MN.

[0139] (3) An SN notified of the termination of Inter-MN LTM may decide to initiate an Inter-SN LTM procedure for the UE.

[0140]

[0141] FIG. 5 is a diagram illustrating an example of a process for notifying an SN of an inter-MN LTM in a system applicable to the present disclosure.

[0142] FIG. 6 is a diagram illustrating an example of a process for notifying an SN of an inter-MN LTM in a system applicable to the present disclosure.

[0143] Direct Inter-MN LTM initiation notification to SN

[0144] The UE is currently served by the S-MN, and the S-MN determines the Inter-MN LTM for the UE.

[0145] Step 1: The S-MN informs the SN of the Inter-MN LTM initiation for the UE.

[0146] Step 2: The SN responds to the S-MN. The response message may contain the updated SCG configuration. For example, if an Intra-SN LTM is configured and in progress in the UE, the SN may decide to reconfigure the UE to release the Intra-SN LTM due to potential master key changes (because the SN key to be used by the SN and the UE has to be updated when the serving MN changes by the Inter-MN LTM operation, which may incur additional RRC reconfigurations in the middle of the Intra-SN LTM).

[0147] The SN does not trigger Inter-SN LTM for the UE to avoid simultaneous Inter-CU LTM configuration in both the MCG and SCG.

[0148] Step 3: The SN may reject the S-MN's request (e.g., if the Inter-SN LTM has already been configured and is in progress on the UE). In that case, the SN informs the S-MN of the reason for the rejection. (Step 3: The SN may reject the S-MN's request (e.g., if the Inter-SN LTM has already been configured and is in progress on the UE). In that case, the SN informs the S-MN of the reason for the rejection.)

[0149]

[0150] Indirect Inter-MN LTM initiation notification to SN

[0151] The UE is currently served by the S-MN, and the S-MN determines the Inter-MN LTM for the UE.

[0152] Step 4: The S-MN requests Inter-MN LTM to a suitable C-MN. The request message to the C-MN may include the indication for Inter-MN LTM initiation, the SN UE X2 / XnAP ID with the S-MN, and the SN ID.

[0153] Step 5: The requested C-MN requests to add the UE to the SN. The request message to the SN may include the indication for Inter-MN LTM initiation, the SN UE X2 / XnAP ID with the S-MN, and the SN ID, so that the SN can identify that the UE requested to be added has been associated with the S-MN and its existing UE context in the SN, and that Inter-MN LTM is initiated for this UE.

[0154] Step 6: SN responds to C-MN. The response message may contain the updated SCG configuration. For example, if Intra-SN LTM is configured and in progress in the UE, SN may decide to reconfigure UE to release Intra-SN LTM due to potential master key changes (because SN key to be used by SN and UE has to be updated when the serving MN changes by Inter-MN LTM operation, which may incur additional RRC reconfigurations in the middle of Intra-SN LTM).

[0155] A successful response from the SN is further replied back to the S-MN, which may include the prepared Inter-MN LTM configuration between the C-MN and the SN, and the updated SCG configuration.

[0156] The SN does not trigger Inter-SN LTM for the UE to avoid simultaneous Inter-CU LTM configuration in both the MCG and SCG.

[0157] Step 7: The SN may reject the C-MN's request (e.g., if an Inter-SN LTM has already been configured and is in progress on the UE). In that case, the SN informs the C-MN of the reason for the rejection, which is then replied to the S-MN. (Step 7: The SN may reject the C-MN's request (e.g., if an Inter-SN LTM has already been configured and is in progress on the UE). In that case, the SN informs the C-MN of the reason for the rejection, which is then replied to the S-MN.)

[0158]

[0159] Direct Inter-MN LTM termination notification to SN

[0160] The UE is currently served by a C-MN, and the current serving MN decides to release the Inter-MN LTM for the UE.

[0161] Step 8: The current serving MN informs the SN of the termination of the Inter-MN LTM for the UE.

[0162] Step 9: The SN responds back to the current serving MN. The response message may contain the updated SCG configuration.

[0163] The SN can now decide to trigger Inter-SN LTM for the UE.

[0164] Step 10: The current serving MN reconfigures the UE via RRC, which may include the release of the Inter-MN LTM and the updated SCG configuration (if any).

[0165]

[0166] Indirect Inter-MN LTM termination notification to SN

[0167] The UE is currently served by a C-MN, and the current serving MN decides to release the Inter-MN LTM for the UE.

[0168] Step 11: The current serving MN initiates the termination of the UE's Inter-MN LTM to the other involved MN(s).

[0169] Step 12: The contacted MN notifies the SN of the termination of the Inter-MN LTM by requesting the release of the SN for the UE. The request message may include the reason for the release due to the Inter-MN LTM termination.

[0170] SN can now trigger Inter-SN LTM for the UE.

[0171]

[0172] Embodiment 2: Inter-SN LTM termination notification to MN

[0173] After Inter-SN LTM is successfully prepared and configured to the UE (with MN unchanged), once the current serving SN (either S-SN or one of C-SN(s) that is currently serving the UE) decides to release Inter-SN LTM for the UE,

[0174] (1) If SRB3 is configured, the current serving SN may notify the MN of the termination of Inter-SN LTM after releasing Inter-SN LTM from the UE via SRB3.

[0175] (2) Alternatively, the current serving SN may release the Inter-SN LTM from the UE via the MN, thereby also notifying the MN of the termination of the Inter-SN LTM.

[0176] (3) The MN notified of the termination of Inter-SN LTM may cancel Inter-SN LTM with other involved SN(s) by releasing those SN(s) for the UE, and may further decide to initiate Inter-MN LTM procedure for the UE.

[0177]

[0178] FIG. 7 is a diagram illustrating an example of a process for notifying an MN of inter-SN LTM termination in a system applicable to the present disclosure.

[0179] FIG. 8 is a diagram illustrating an example of a process for notifying an MN of inter-SN LTM termination in a system applicable to the present disclosure.

[0180] Inter-SN LTM termination notification to MN when releasing Inter-SN LTM from the UE via SRB3

[0181] The UE is currently served by the MN and S-SN, and the current serving SN decides to release the Inter-SN LTM for the UE.

[0182] Step 1: The current serving SN releases Inter-SN LTM from the UE via RRC.

[0183] Step 2: The current serving SN informs the MN of the termination of the Inter-SN LTM.

[0184] MN can now trigger Inter-MN LTM for the UE.

[0185] Step 3: The MN requests the release of other SN(s) involved in the Inter-SN LTM for the UE. The request message may include the reason for the release due to the termination of the Inter-SN LTM.

[0186] Inter-SN LTM termination notification to MN when releasing Inter-SN LTM from the UE via MN

[0187] The UE is currently served by the MN and C-SN, and the current serving SN decides to release the Inter-SN LTM for the UE.

[0188] Step 4: The current serving SN requests the MN to reconfigure the UE. The request message may include an indication of Inter-SN LTM termination and the updated SCG configuration. The MN further reconfigures the UE via RRC, releasing Inter-SN LTM from the UE and updating the MCG / SCG configuration, if any.

[0189] MN can now trigger Inter-MN LTM for the UE.

[0190] Step 5: The MN requests the release of other SN(s) involved in the Inter-SN LTM for the UE. The request message may include the reason for the release due to the termination of the Inter-SN LTM.

[0191]

[0192] Technical features of various embodiments of the present disclosure

[0193] Advantageous Effects

[0194] The inventions described in this present disclosure ensure that Inter-CU LTM does not get configured to the UE both in MN and in SN at the same time for Rel-19 cases of Inter-SN-CU LTM (MN unchanged) and Inter-MN-CU LTM (SN unchanged).

[0195]

[0196] [Description of the first node (S-MN-CU or C-MN-CU) claim]

[0197] The embodiments described below are specifically described with reference to FIG. 9 in terms of the operation of the first node. The methods described below are distinguished for convenience of explanation, and it is understood that some components of one method may be substituted for or combined with some components of another method, as long as they are not mutually exclusive.

[0198] FIG. 9 is a diagram illustrating an example of the operation process of the first node in a system applicable to the present disclosure.

[0199] In the embodiment of FIG. 9, the first node may correspond to an S-MN-CU or a C-MN-CU, and the second node may correspond to an SN.

[0200] At step S910, the first node transmits a first message to the second node not allowing configuration of inter-secondary node layer1 / layer2-triggered mobility (Inter-SN LTM) based on initiation of inter-master node layer1 / layer2-triggered mobility (Inter-MN LTM).

[0201] At step S920, the first node transmits a second message to the second node allowing the establishment of the Inter-SN LTM based on the termination of the Inter-MN LTM.

[0202]

[0203] According to various embodiments of the present disclosure, an MN serving a master cell group (MCG) of a user equipment (UE) may be changed from a source master node (S-MN) to a candidate master node (C-MN) through inter-MN LTM. The second node may be a secondary node (SN) serving a secondary cell group (SCG) of the UE.

[0204] According to various embodiments of the present disclosure, the first node may be a CU of S-MN (S-MN-CU), which is a centralized unit (CU) of the S-MN. The first message may be directly transmitted from the first node to the second node, or the first message may be transmitted from the first node to the second node via a CU of C-MN (C-MN-CU), which is a CU of the C-MN.

[0205] According to various embodiments of the present disclosure, the first node may be a C-MN-CU (CU of C-MN), which is a CU of the C-MN. Based on receiving a message indicating the initiation of the LTM between the MNs from the S-MN-CU (CU of S-MN), which is a CU (centralized unit) of the S-MN, the first message may be directly transmitted from the first node to the second node.

[0206] According to various embodiments of the present disclosure, the embodiment of FIG. 9 may further include a step of receiving an updated secondary cell group configuration (updated SCG configuration) from the second node in response to the first message or the second message.

[0207] According to various embodiments of the present disclosure, the embodiment of FIG. 9 may further include, in response to the first message, a step of receiving a rejection response for the first message from the second node. The reason for rejection included in the rejection response may be that the inter-SN LTM is already on-going.

[0208] According to various embodiments of the present disclosure, the embodiment of FIG. 9 may further include a step of receiving a third message including information indicating that configuration of the Inter-MN LTM is possible from the second node based on termination of the Inter-SN LTM.

[0209]

[0210] According to various embodiments of the present disclosure, a first node is provided in a wireless communication system. The first node includes a transceiver and at least one processor, wherein the at least one processor may be configured to perform the operating method of the first node according to FIG. 9.

[0211]

[0212] According to various embodiments of the present disclosure, a device for controlling a first node in a wireless communication system is provided. The device includes at least one processor and at least one memory operably connected to the at least one processor. The at least one memory may be configured to store instructions for performing the operating method of the first node according to FIG. 9 based on instructions executed by the at least one processor.

[0213]

[0214] According to various embodiments of the present disclosure, one or more non-transitory computer-readable media (CRM) storing one or more instructions are provided. The one or more instructions, when executed by one or more processors, perform operations, and the operations may include the operating method of the first node according to FIG. 9.

[0215]

[0216] [Description of the second node (SN) claim]

[0217] The embodiments described below are specifically described with reference to FIG. 10 in terms of the operation of the second node. The methods described below are distinguished for convenience of explanation, and it is understood that some components of one method may be substituted for or combined with some components of another method, as long as they are not mutually exclusive.

[0218] FIG. 10 is a diagram illustrating an example of the operation process of a second node in a system applicable to the present disclosure.

[0219] In the embodiment of FIG. 10, the first node may correspond to an S-MN-CU or a C-MN-CU, and the second node may correspond to an SN.

[0220] At step S1010, the second node receives a first message from the first node that does not allow configuration of inter-secondary node layer1 / layer2-triggered mobility (Inter-SN LTM) based on initiation of inter-master node layer1 / layer2-triggered mobility (Inter-MN LTM).

[0221] At step S1020, the second node receives a second message from the first node allowing the establishment of the Inter-SN LTM based on the termination of the Inter-MN LTM.

[0222]

[0223] According to various embodiments of the present disclosure, an MN serving a master cell group (MCG) of a user equipment (UE) may be changed from a source master node (S-MN) to a candidate master node (C-MN) through inter-MN LTM. The second node may be a secondary node (SN) serving a secondary cell group (SCG) of the UE.

[0224] According to various embodiments of the present disclosure, the first node may be a CU of S-MN (S-MN-CU), which is a centralized unit (CU) of the S-MN. The first message may be directly received from the first node by the second node, or the first message may be received from the first node by the second node through a CU of C-MN (C-MN-CU), which is a CU of the C-MN.

[0225] According to various embodiments of the present disclosure, the first node may be a C-MN-CU (CU of C-MN), which is a CU of the C-MN. Based on receiving a message indicating the initiation of the LTM between the MNs from the S-MN-CU (CU of S-MN), which is a CU (centralized unit) of the S-MN, the first message may be directly received by the second node from the first node.

[0226] According to various embodiments of the present disclosure, the embodiment of FIG. 10 may further include a step of transmitting an updated secondary cell group configuration (updated SCG configuration) to the first node in response to the first message or the second message.

[0227] According to various embodiments of the present disclosure, the embodiment of FIG. 10 may further include, in response to the first message, a step of transmitting a rejection response to the first message to the first node. The reason for rejection included in the rejection response may be that the inter-SN LTM is already on-going.

[0228] According to various embodiments of the present disclosure, the embodiment of FIG. 10 may further include a step of transmitting a third message including information indicating that configuration of the Inter-MN LTM is possible to the first node based on termination of the Inter-SN LTM.

[0229]

[0230] According to various embodiments of the present disclosure, a second node is provided in a wireless communication system. The second node includes a transceiver and at least one processor, wherein the at least one processor may be configured to perform the operating method of the second node according to FIG. 10.

[0231]

[0232] According to various embodiments of the present disclosure, a device for controlling a second node in a wireless communication system is provided. The device includes at least one processor and at least one memory operably connected to the at least one processor. The at least one memory may be configured to store instructions for performing the operating method of the second node according to FIG. 10 based on instructions executed by the at least one processor.

[0233]

[0234] According to various embodiments of the present disclosure, one or more non-transitory computer-readable media (CRM) storing one or more instructions are provided. The one or more instructions, when executed by one or more processors, perform operations, and the operations may include the operating method of a second node according to FIG. 10.

[0235]

[0236] Wireless devices applicable to the present disclosure

[0237] Below, examples of wireless devices to which various embodiments of the present disclosure are applied are described.

[0238] FIG. 11 is a diagram illustrating an example of the structure of a first node and a second node in a system applicable to the present disclosure.

[0239] The first node (1600) may include a processor (1610), an antenna unit (1620), a transceiver (1630), and a memory (1640).

[0240] The processor (1610) performs baseband-related signal processing and may include a higher layer processing unit (1611) and a physical layer processing unit (1615). The higher layer processing unit (1611) may process operations of a MAC layer, an RRC layer, or higher layers. The physical layer processing unit (1615) may process operations of a PHY layer. For example, when the first node (1600) is a base station device in base station-to-terminal communication, the physical layer processing unit (1615) may perform uplink reception signal processing, downlink transmission signal processing, etc. For example, when the first node (1600) is a first terminal device in terminal-to-terminal communication, the physical layer processing unit (1615) may perform downlink reception signal processing, uplink transmission signal processing, sidelink transmission signal processing, etc. In addition to performing baseband-related signal processing, the processor (1610) may also control the overall operation of the first node (1600).

[0241] The antenna unit (1620) may include one or more physical antennas, and when it includes multiple antennas, it may support MIMO transmission and reception. The transceiver (1630) may include an RF (Radio Frequency) transmitter and an RF receiver. The memory (1640) may store information processed by the processor (1610), software, an operating system, applications, etc. related to the operation of the first node (1600), and may also include components such as a buffer.

[0242] The processor (1610) of the first node (1600) may be configured to implement the operation of the base station in the base station-to-terminal communication (or the operation of the first terminal device in the terminal-to-terminal communication) in the embodiments described in the present disclosure.

[0243]

[0244] The second node (1650) may include a processor (1660), an antenna unit (1670), a transceiver (1680), and a memory (1690).

[0245] The processor (1660) performs baseband-related signal processing and may include a higher layer processing unit (1661) and a physical layer processing unit (1665). The higher layer processing unit (1661) may process operations of a MAC layer, an RRC layer, or higher layers. The physical layer processing unit (1665) may process operations of a PHY layer. For example, when the second node (1650) is a terminal device in base station-terminal communication, the physical layer processing unit (1665) may perform downlink reception signal processing, uplink transmission signal processing, etc. For example, when the second node (1650) is a second terminal device in terminal-to-terminal communication, the physical layer processing unit (1665) may perform downlink reception signal processing, uplink transmission signal processing, sidelink reception signal processing, etc. In addition to performing baseband-related signal processing, the processor (1660) may also control the overall operation of the second node (1660).

[0246] The antenna unit (1670) may include one or more physical antennas, and when it includes multiple antennas, it may support MIMO transmission and reception. The transceiver (1680) may include an RF transmitter and an RF receiver. The memory (1690) may store information processed by the processor (1660), software, an operating system, applications, etc. related to the operation of the second node (1650), and may also include components such as a buffer.

[0247] The processor (1660) of the second node (1650) may be configured to implement operations of a terminal in base station-to-terminal communication (or operations of a second terminal device in terminal-to-terminal communication) in the embodiments described in the present disclosure.

[0248] In the operation of the first node (1600) and the second node (1650), the same explanations for the base station and the terminal (or the first terminal and the second terminal in the terminal-to-terminal communication) in the examples of the present disclosure may be applied, and redundant explanations are omitted.

[0249]

[0250] Here, the wireless communication technology implemented in the device (1600, 1650) of the present disclosure may include various other wireless communication technologies as well as LTE, NR, and 6G.

[0251]

[0252] The claims described in the various embodiments of the present disclosure may be combined in various ways. For example, the technical features of the method claims of the various embodiments of the present disclosure may be combined and implemented as a device, and the technical features of the device claims of the various embodiments of the present disclosure may be combined and implemented as a method. Furthermore, the technical features of the method claims of the various embodiments of the present disclosure may be combined and implemented as a device, and the technical features of the method claims of the various embodiments of the present disclosure may be combined and implemented as a method.

Claims

1. In a method performed by the first node, A step of transmitting a first message to a second node not allowing configuration of inter-secondary node layer1 / layer2-triggered mobility (Inter-SN LTM) based on initiation of inter-master node layer1 / layer2-triggered mobility (Inter-MN LTM); A step of transmitting a second message allowing the establishment of the Inter-SN LTM to the second node based on the termination of the Inter-MN LTM, method.

2. In paragraph 1, Through the above MN LTM (Inter-MN LTM), the MN serving the MCG (master cell group) of the UE (user equipment) is changed from the S-MN (source master node) to the C-MN (candidate master node), The second node is a secondary node (SN) serving the secondary cell group (SCG) of the UE. method.

3. In paragraph 2, The above first node is a S-MN-CU (CU of S-MN), which is a CU (centralized unit) of the S-MN, The first message is directly transmitted from the first node to the second node, or the first message is transmitted from the first node to the second node through a C-MN-CU (CU of C-MN), which is a CU of the C-MN. method.

4. In paragraph 2, The above first node is a C-MN-CU (CU of C-MN), which is a CU of the C-MN, Based on receiving a message notifying the initiation of LTM between the MNs from the S-MN-CU (CU of S-MN), which is a CU (centralized unit) of the S-MN, the first message is directly transmitted from the first node to the second node. method.

5. In paragraph 2, Further comprising a step of receiving an updated secondary cell group configuration (updated SCG configuration) from the second node in response to the first message or the second message. method.

6. In paragraph 1, In response to the first message, further comprising the step of receiving a rejection response to the first message from the second node, The reason for rejection included in the above rejection response is that the inter-SN LTM is already on-going. method.

7. In paragraph 1, Further comprising a step of receiving a third message including information indicating that configuration of the Inter-MN LTM is possible from the second node based on the termination of the Inter-SN LTM. method.

8. In a method performed by a second node, A step of receiving a first message from a first node that does not allow configuration of inter-secondary node layer1 / layer2-triggered mobility (Inter-SN LTM) based on initiation of inter-master node layer1 / layer2-triggered mobility (Inter-MN LTM); A step of receiving a second message allowing the establishment of the Inter-SN LTM from the first node based on the termination of the Inter-MN LTM, method.

9. In paragraph 8, Through the above MN LTM (Inter-MN LTM), the MN serving the MCG (master cell group) of the UE (user equipment) is changed from the S-MN (source master node) to the C-MN (candidate master node), The second node is a secondary node (SN) serving the secondary cell group (SCG) of the UE. method.

10. In paragraph 9, The above first node is a S-MN-CU (CU of S-MN), which is a CU (centralized unit) of the S-MN, The first message is directly received from the first node by the second node, or the first message is received from the first node by the second node through a C-MN-CU (CU of C-MN), which is a CU of the C-MN. method.

11. In paragraph 9, The above first node is a C-MN-CU (CU of C-MN), which is a CU of the C-MN, Based on receiving a message notifying the initiation of LTM between the MNs from the S-MN-CU (CU of S-MN), which is a CU (centralized unit) of the S-MN, the first message is directly received from the first node by the second node. method.

12. In paragraph 9, Further comprising a step of transmitting an updated secondary cell group configuration (updated SCG configuration) to the first node in response to the first message or the second message. method.

13. In paragraph 8, In response to the first message, further comprising the step of transmitting a rejection response to the first message to the first node, The reason for rejection included in the above rejection response is that the inter-SN LTM is already on-going. method.

14. In paragraph 8, Further comprising a step of transmitting a third message including information indicating that configuration of the Inter-MN LTM is possible to the first node based on the termination of the Inter-SN LTM. method.

15. In the first node, Transmitter and receiver; at least one processor; and At least one memory operably connectable to said at least one processor and storing instructions that, when executed by said at least one processor, perform operations; The above actions are, Comprising all steps of the method according to any one of claims 1 to 7, Node 1.

16. In the second node, Transmitter and receiver; at least one processor; and At least one memory operably connectable to said at least one processor and storing instructions that, when executed by said at least one processor, perform operations; The above actions are, Comprising all steps of the method according to any one of claims 8 to 14, Second node.

17. In a control device that controls the first node, at least one processor; and comprising at least one memory operably connected to at least one of the processors; The at least one memory stores instructions for performing operations based on being executed by the at least one processor, The above actions are, Comprising all steps of the method according to any one of claims 1 to 7, controller.

18. In a control device that controls the second node, at least one processor; and comprising at least one memory operably connected to at least one of the processors; The at least one memory stores instructions for performing operations based on being executed by the at least one processor, The above actions are, Comprising all steps of the method according to any one of claims 8 to 14, controller.

19. In a non-transitory computer-readable medium storing one or more instructions, The one or more instructions perform operations based on being executed by one or more processors, The above actions are, Comprising all steps of the method according to any one of claims 1 to 7, Computer readable medium.

20. In a non-transitory computer-readable medium storing one or more instructions, The one or more instructions perform operations based on being executed by one or more processors, The above actions are, Comprising all steps of the method according to any one of claims 8 to 14, Computer readable medium.

Images