Method and apparatus for determining completion of cell change triggered by layer 1 / layer 2 in next generation mobile communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The present disclosure relates to a method and apparatus for operating a terminal in a wireless communication system, the method comprising the steps of: receiving, from a base station, an RRC message including configuration information related to L1 / L2 triggered mobility (LTM); receiving, from the base station, a physical downlink control channel (PDCCH) order for early timing advance (TA); transmitting a layer 1 (L1) measurement report to the base station; receiving, from the base station, LTM medium access control control element (MAC CE) on the basis of the L1 measurement report; and determining whether to perform random access channel (RACH)-less handover on the basis of the LTM MAC CE.

Description

Method and device for determining completion of cell change triggered by layer 1 / layer 2 in next-generation mobile communication system

[0001] The present disclosure relates to the operation of terminals and base stations in a mobile communication system. Furthermore, the present disclosure relates to a method for determining the completion of a cell change triggered by Layer 1 / Layer 2 in a next-generation mobile communication system.

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

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

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

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

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

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

[0008] The present disclosure provides a method for performing a cell change to a neighboring cell when a UE is currently receiving service from a serving cell through a specific beam by measuring and reporting a beam belonging to another cell and finding that the beam of the neighboring cell is better. That is, the present disclosure clearly defines how the RACH-less cell change is completed when a RACH-less cell change occurs through LTM (L1 / L2 triggered mobility), so that subsequent operations of the UE and the base station can be defined. In particular, the present disclosure determines that voice service needs to be supported without interruption even after an LTM cell change, and provides a RACH-less cell change completion operation that takes this into consideration.

[0009] According to one embodiment of the present disclosure, a method for operating a terminal in a wireless communication system is provided, the method comprising the steps of: receiving an RRC message including LTM (L1 / L2 triggered mobility) related configuration information from a base station; receiving a PDCCH (physical downlink control channel) order for Early TA (timing advance) from the base station; transmitting an L1 (layer 1) measurement report to the base station; receiving an LTM MAC CE (medium access control control element) from the base station based on the L1 measurement report; and determining whether to perform a RACH (random access channel)-less handover based on the LTM MAC CE.

[0010] According to one embodiment of the present disclosure, a method of a terminal in a wireless communication system comprises the steps of: receiving a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information from a first cell; transmitting an L1 (layer 1) measurement report to the first cell; receiving a PDCCH (physical downlink control channel) order for Early TA (timing advance) from the first cell; transmitting a preamble for the Early TA to a second cell; receiving an LTM MAC CE (medium access control control element) indicating handover to the second cell from the first cell; transmitting a second RRC message to the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE; receiving a third RRC message from the second cell; and transmitting an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message. A method is provided, including a step of determining the success of a handover based on the LTM, based on the identifier.

[0011] In addition, according to one embodiment of the present disclosure, in a method of a base station in a wireless communication system, the method comprises the steps of: transmitting a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information to a terminal through a first cell of the base station; receiving an L1 (layer 1) measurement report from the terminal through the first cell; transmitting a PDCCH (physical downlink control channel) order for Early TA (timing advance) to the terminal through the first cell; receiving a preamble for the Early TA from the terminal through a second cell; transmitting an LTM MAC CE (medium access control control element) indicating handover to the second cell to the terminal through the first cell; receiving a second RRC message from the terminal through the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE; and transmitting a third RRC message to the terminal through the second cell. The present invention provides a method for determining the success of a handover based on the LTM, based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

[0012] In addition, according to one embodiment of the present disclosure, a terminal of a wireless communication system includes a transceiver and a control unit, wherein the control unit receives a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information from a first cell, transmits an L1 (layer 1) measurement report to the first cell, receives a PDCCH (physical downlink control channel) order for Early TA (timing advance) from the first cell, transmits a preamble for the Early TA to a second cell, receives an LTM MAC CE (medium access control control element) indicating handover to the second cell from the first cell, and transmits a second RRC message to the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE.

[0013] A terminal is provided that receives a third RRC message from the second cell, and determines the success of handover based on the LTM based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

[0014] In addition, according to one embodiment of the present disclosure, a base station of a wireless communication system includes a transceiver and a control unit, wherein the control unit transmits a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information to a terminal through a first cell of the base station, receives an L1 (layer 1) measurement report from the terminal through the first cell, transmits a PDCCH (physical downlink control channel) order for Early TA (timing advance) to the terminal through the first cell, receives a preamble for the Early TA from the terminal through a second cell, transmits an LTM MAC CE (medium access control control element) indicating handover to the second cell to the terminal through the first cell, and receives a second RRC message from the terminal through the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE, and then transmits a third RRC message through the second cell. A base station is provided that controls transmission of a message to the terminal and determines the success of handover based on the LTM based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

[0015] The technical problems to be achieved in the embodiments of the present invention 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 invention belongs from the description below.

[0016] According to various embodiments of the present disclosure, a method for determining completion of a cell change triggered by layer 1 / layer 2 in a next-generation mobile communication system and a device for performing the same can be provided.

[0017] According to the definition of the LTM RACH-less cell change completion operation proposed in various embodiments of the present disclosure, a terminal and a base station can determine which operation can complete a RACH-less cell change, and can be applied to various services to reduce interruption. In other words, voice services can be supported without interruption even after an LTM cell change.

[0018] FIG. 1 is a diagram illustrating the structure of a next-generation mobile communication system to which the present disclosure is applied.

[0019] FIG. 2 is a diagram showing a wireless protocol structure of a next-generation mobile communication system to which the present disclosure can be applied.

[0020] FIG. 3 is a diagram illustrating the structure of another next-generation mobile communication system to which the present disclosure can be applied.

[0021] FIG. 4 is a diagram illustrating a scenario in which a terminal changes a serving cell and beam to a TRP (transmission reception point) of a target cell that supports L1 / L2-based cell change, as an LTM (L1 / L2 triggered mobility) scenario applicable to the present disclosure, and transmits and receives data.

[0022] FIG. 5 is a description of the downlink SPS (semi-persistent scheduling) operation and the uplink Configured Grant operation applied to the present disclosure.

[0023] FIGS. 6a and 6b are drawings illustrating an embodiment applicable to the present disclosure, which depicts an entire procedure for supporting an operation of determining handover completion in a target cell after LTM RACH-less cell change is performed and performing periodic transmission without interruption.

[0024] FIG. 7 is a diagram illustrating terminal operation from the entire terminal operation of performing L1 / L2 inter-cell handover to completion of LTM RACH-less cell change, which is applied to embodiments of the present disclosure.

[0025] FIG. 8 is a diagram illustrating base station operations applied to embodiments of the present disclosure.

[0026] Figure 9 is a drawing showing the configuration of a terminal according to the present disclosure.

[0027] Figure 10 is a drawing showing the configuration of a base station according to the present disclosure.

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. It should be noted that, where possible, identical components are represented by identical reference numerals throughout the attached drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted.

[0029] In describing the embodiments herein, descriptions of technical details that are well-known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to avoid obscuring the gist of the present invention by omitting unnecessary explanations and to convey the gist more clearly.

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

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

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

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

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

[0035] Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a Node B, a BS (base station), an eNB (eNode B), a gNB (gNode B), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (user equipment), an MS (mobile station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In addition, the embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel type to the embodiments of the present disclosure described below. In addition, the embodiments of the present disclosure may be applied to other communication systems with some modifications without significantly departing from the scope of the present disclosure at the discretion of a person having skilled technical knowledge. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included here, and the 5G below may also be a concept that includes existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications within a scope that does not significantly deviate from the scope of the present disclosure, as judged by a person having skilled technical knowledge.

[0036] In the following description, terms used to identify connection nodes, terms referring to network entities or network functions (NFs), terms referring to messages, terms referring to interfaces between network objects, terms referring to various identification information, etc. are examples provided for convenience of explanation. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0037] For convenience of explanation below, some terms and names defined in the 3rd generation partnership project (3GPP) LTE (long term evolution) standard and / or 3GPP NR (new radio) standard may be used. However, the present invention is not limited to the above terms and names, and can be equally applied to systems conforming to other standards.

[0038] Additionally, in the present disclosure, L1 / L2-based mobility support is used interchangeably as L1 / L2 handover, L1 / L2 triggered mobility (LTM), L1 / L2 triggered mobility, etc.

[0039] Figure 1 is a diagram illustrating the structure of a next-generation mobile communication system to which the present disclosure is applied.

[0040] Referring to FIG. 1, as illustrated, a wireless access network of a next-generation mobile communication system is composed of a next-generation base station (New Radio Node B, hereinafter referred to as NR NB, 1-10) and a new radio core network (NR CN, or NG CN: next generation core network, 1-05). A user terminal (new radio user equipment, hereinafter referred to as NR UE or terminal, 1-15) accesses an external network through the NR NB (1-10) and the NR CN (1-05). In various embodiments of the present disclosure, NR NB and NR gNB are used as the same concept.

[0041] In Fig. 1, NR NB (1-10) corresponds to the eNB (Evolved Node B) of the existing LTE system. NR NB is connected to NR UE (1-15) via a wireless channel and can provide superior service than the existing Node B. In the next-generation mobile communication system, all user traffic is serviced through a shared channel, so a device that collects status information such as buffer status, available transmission power status, and channel status of UEs and performs scheduling is required, and this is handled by NR NB (1-10). One NR NB typically controls multiple cells. In order to implement ultra-high-speed data transmission compared to the existing LTE, it can have a bandwidth higher than the existing maximum, and beamforming technology can be additionally grafted using orthogonal frequency division multiplexing (OFDM) as a wireless access technology. In addition, it applies an adaptive modulation & coding (AMC) method that determines a modulation scheme and channel coding rate according to the channel status of the terminal. NR CN (1-05) performs functions such as mobility support, bearer setup, and QoS (quality of service) setup. NR CN (1-05) is a device that handles various control functions as well as mobility management functions for terminals and is connected to multiple base stations. In addition, the next-generation mobile communication system can also be linked with the existing LTE system, and NR CN (1-05) is connected to MME (1-25) through a network interface. MME (1-25) is connected to eNB (1-30), which is an existing base station.

[0042] FIG. 2 is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system to which various embodiments of the present disclosure can be applied.

[0043] Referring to FIG. 2, the wireless protocol of the next-generation mobile communication system consists of NR SDAP (service data adaptation protocol) (2-01, 2-45), NR PDCP (packet data convergence protocol) (2-05, 2-40), NR RLC (radio link control) (2-10, 2-35), and NR MAC (medium access control) (2-15, 2-30) in the terminal and NR base station, respectively.

[0044] Key features of NR SDAP (2-01, 2-45) may include some of the following:

[0045] - Transfer of user plane data

[0046] - Mapping between a QoS flow and a data radio bearer (DRB) for both downlink (DL) and uplink (UL)

[0047] - Marking function of QoS flow ID for both uplink and downlink (marking QoS flow ID in both DL and UL packets)

[0048] - Ability to map relective QoS flow to data bearer for uplink SDAP protocol data units (PDUs) (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0049] For the above SDAP layer device, the terminal can be configured by an RRC (radio resource control) message for each PDCP layer device, each bearer, or each logical channel, whether to use the header of the SDAP layer device or whether to use the function of the SDAP layer device, and when the SDAP header is configured, the terminal can be instructed to update or reset the mapping information for the QoS flow and data bearer of the uplink and downlink with a 1-bit indicator for reflecting NAS (non access stratum) QoS (NAS reflective QoS) and a 1-bit indicator for reflecting AS QoS (AS reflective QoS) in the SDAP header. The SDAP header can include QoS flow ID information indicating QoS. The QoS information can be used as data processing priority, scheduling information, etc. to support a smooth service.

[0050] Key features of NR PDCP (2-05, 2-40) may include some of the following:

[0051] ● Header compression and decompression (ROHC only)

[0052] ● User data transfer function

[0053] ● In-sequence delivery of upper layer PDUs

[0054] ● Out-of-sequence delivery of upper layer PDUs

[0055] ● Reordering function (PDCP PDU reordering for reception)

[0056] ● Duplicate detection of lower layer SDUs

[0057] ● Retransmission function (Retransmission of PDCP SDUs)

[0058] ● Encryption and decryption functions (Ciphering and deciphering)

[0059] ● Timer-based SDU discard in uplink

[0060] The reordering function of the NR PDCP device above refers to a function of reordering PDCP PDUs received from a lower layer in order based on the PDCP SN (sequence number), and may include a function of transmitting data to an upper layer in the reordered order, or may include a function of transmitting data directly without considering the order, may include a function of recording lost PDCP PDUs by reordering the order, may include a function of reporting the status of lost PDCP PDUs to the transmitting side, and may include a function of requesting retransmission of lost PDCP PDUs.

[0061] The main features of NR RLC(2-10, 2-35) may include some of the following:

[0062] ● Data transfer function (Transfer of upper layer PDUs)

[0063] ● In-sequence delivery of upper layer PDUs

[0064] ● Out-of-sequence delivery of upper layer PDUs

[0065] ● ARQ function (Error Correction through ARQ)

[0066] ● Concatenation, segmentation and reassembly of RLC SDUs

[0067] ● Re-segmentation of RLC data PDUs

[0068] ● Reordering of RLC data PDUs

[0069] ● Duplicate detection function

[0070] ● Error detection function (Protocol error detection)

[0071] ● RLC SDU discard function

[0072] ● RLC re-establishment function

[0073] The in-sequence delivery function of the NR RLC device above refers to the function of sequentially transmitting RLC SDUs received from a lower layer to an upper layer, and may include a function of reassembling and transmitting RLC SDUs when an RLC SDU is originally received divided into multiple RLC SDUs, may include a function of reordering received RLC PDUs based on RLC SN (sequence number) or PDCP SN (sequence number), may include a function of recording lost RLC PDUs by reordering the sequence, may include a function of reporting the status of lost RLC PDUs to the transmitting side, may include a function of requesting retransmission of lost RLC PDUs, may include a function of sequentially transmitting only RLC SDUs up to the lost RLC SDU to an upper layer when there is a lost RLC SDU, or may include a function of sequentially transmitting all RLC SDUs received before the timer starts when a predetermined timer expires even when there is a lost RLC SDU. Or, even if there are lost RLC SDUs, if a predetermined timer has expired, it may include a function to sequentially deliver all RLC SDUs received up to the upper layer. In addition, the RLC PDUs may be processed in the order they are received (in the order of arrival, regardless of the order of the sequence number) and delivered to the PDCP device out of sequence (out-of-sequence delivery). In the case of segments, the segments stored in the buffer or to be received later may be received, reconstructed into a single complete RLC PDU, processed, and then delivered to the PDCP device.The above NR RLC layer may not include a concatenation function, and the function may be performed in the NR MAC layer or replaced with a multiplexing function of the NR MAC layer.

[0074] The out-of-sequence delivery function of the NR RLC device above refers to the function of directly delivering RLC SDUs received from a lower layer to an upper layer regardless of the order, and may include a function of reassembling and delivering RLC SDUs when an original RLC SDU is received divided into multiple RLC SDUs, and may include a function of storing the RLC SN or PDCP SN of received RLC PDUs and arranging the order to record lost RLC PDUs.

[0075] NR MAC (2-15, 2-30) can be connected to multiple NR RLC layer devices configured in one terminal, and the main functions of NR MAC can include some of the following functions.

[0076] ● Mapping function (Mapping between logical channels and transport channels)

[0077] ● Multiplexing / demultiplexing of MAC SDUs

[0078] ● Scheduling information reporting function

[0079] ● HARQ (hybrid automatic repeat request) function (Error correction through HARQ)

[0080] ● Priority handling between logical channels of one UE

[0081] ● Priority handling between UEs by means of dynamic scheduling

[0082] ● MBMS service identification function

[0083] ● Transport format selection function

[0084] ● Padding function

[0085] The NR PHY layer (2-20, 2-25) can perform operations such as channel coding and modulating upper layer data, converting it into OFDM symbols and transmitting it through a wireless channel, or demodulating and channel decoding OFDM symbols received through a wireless channel and transmitting them to a higher layer.

[0086] FIG. 3 is a diagram illustrating the structure of another next-generation mobile communication system to which the present disclosure can be applied.

[0087] Referring to FIG. 3, a cell served by an NR gNB (3-05) operating on a beam basis can be composed of multiple TRPs (transmission reception points, 3-10, 3-15, 3-20, 3-25, 3-30, 3-35, 3-40). The TRPs (3-10, 3-15, 3-20, 3-25, 3-30, 3-35~3-40) represent blocks that separate some functions of transmitting and receiving physical signals from an existing NR base station (eNB) and are composed of multiple antennas. The NR gNB (3-05) can also be expressed as a CU (central unit) and the TRP can also be expressed as a DU (distributed unit). The functions of the NR gNB (3-05) and the TRP can be configured by separating each layer in the PDCP / RLC / MAC / PHY layers such as 3-45. That is, TRP (3-15, 3-25) can perform the functions of the corresponding layer with only the PHY layer, TRP (3-10, 3-35, 3-40) can perform the functions of the corresponding layers with only the PHY layer and MAC layer, and TRP (3-20, 3-30), 3-15, 3-20, 3-25, 3-30, 3-35~3-40) can use beamforming technology to transmit and receive data by generating narrow beams in multiple directions using multiple transmit / receive antennas. The user terminal (3-50) connects to the NR gNB (3-05) and an external network through TRP (3-10, 3-15, 3-20, 3-25, 3-30, 3-35~3-40). The above NR gNB (3-05) collects and schedules status information such as buffer status, available transmission power status, and channel status of terminals to provide services to users, thereby supporting connections between the terminals and the core network (CN, core network, 3-05), particularly AMF (access and mobility management function) / SMF (session management function) (3-50).

[0088] In various implementations of the present disclosure, the TRP is based on a structure (3-15, 3-25) that can perform the functions of the corresponding layer with only the PHY layer, but is not limited thereto.

[0089] FIG. 4 is a diagram illustrating a scenario in which a terminal changes a serving cell and beam to a TRP of a target cell that supports L1 / L2-based cell change, as an LTM (L1 / L2 triggered mobility) scenario applicable to the present disclosure, and transmits and receives data.

[0090] Although FIG. 4 describes a case where multiple cells (TRP1-Cell1, TRP2-Cell2; 4-15, 4-20) exist within one DU (distributed unit, 4-10), the overall content of the present disclosure can also be applied to the inter-DU case (where each DU constitutes one TRP-Cell).

[0091] The terminal (4-25) can receive common and dedicated configuration information for the LTM candidate cell (TRP 2-Cell 2, 4-20) from the serving cell (4-15) through RRC configuration information (4-50). That is, overall RRC configuration information, such as cell group configuration (e.g., including ServingCellConfigCommon and ServingCellConfig, etc.), bearer configuration, and measurement configuration associated with the serving cell ID (ServingCellID) or candidate cell ID (candidateCellID, cell ID associated with PCI (physical cell identity)), can be provided in advance to the terminal (4-25) from the serving cell (4-15). The configuration information can be provided in the form of pre-configuration in the RRC configuration, and configuration information for multiple candidate cells can be transmitted. In addition, the setting is characterized in that it includes setting information (cell setting, bearer setting, security key setting, etc.) that is applied when the terminal (4-25) moves (handovers) to the corresponding cell. For example, the setting may include all setting information that is applied when moving (handovers) to the corresponding cell. In addition, unified TCI state setting for the candidate cell and settings related to L1 measurement and reporting may be transmitted together with the setting. In the following embodiments of the present disclosure, in particular, in the above-described situation, when the terminal (4-25) performs a handover by receiving a handover message to the target cell through LTM (L1 / L2 triggered mobility), the terminal (4-25) performs an operation of automatically synchronizing the uplink to the target cell. A detailed method is described in the following embodiments.

[0092] After the configuration for TRP 2-Cell 2 (4-20) is provided to the serving cell 1 (4-15) in an RRC connection state, the terminal (4-25) performs L1 measurement for the corresponding TRP 2-Cell 2 (4-20) according to the configuration received in step 4-55 and reports the result to the serving cell (Cell 1, 4-15). If the serving cell determines that a handover is necessary simultaneously with a beam change to a specific beam (TCI state 2, 4-40) of TRP 2 (Cell 2, 4-20) rather than the serving cell beam (TCI state 1, 4-30) based on the measurement result, it triggers the beam change and handover in step 4-60 and instructs the terminal (4-25) through L1 / L2 signaling. The terminal (4-25) performs a handover to TRP 2 (Cell 2, 4-20) simultaneously with a beam change through the instruction, and transmits and receives data through the TRP 2 (Cell 2, 4-20). At this time, the terminal (4-25) applies the configuration information for the target cell where the handover is performed, which was previously set in step 4-50. Depending on whether uplink synchronization is required in the step, the terminal (4-25) may perform random access or may omit random access to the target cell. Detailed operations are described in the drawings below.

[0093] In the present disclosure, in relation to LTM (L1 / L2 triggered mobility) operation, in particular, when RACH-less LTM cell change is performed for an LTM candidate target cell by early TA (timing advance) operation and UE-based TA acquisition, we aim to define detailed operations for determining the completion of the RACH-less cell change. In particular, when a UE is instructed to perform a RACH-less LTM cell change, the UE can be configured with a Configured Grant (CG) Type 1 resource for the RACH-less LTM cell change, and the UE performs a first uplink transmission with the resource. The uplink transmission includes an RRC Reconfiguration Complete message for the target cell. Thereafter, the base station responds to the uplink transmission (transmits a response message to the UE), thereby indicating to the UE that the LTM cell change has been completed. In embodiments of the present disclosure, we aim to describe methods that can be used for such a procedure. In particular, a feature of the present disclosure is that it is thought necessary to support voice services without interruption even after an LTM cell change, and for this purpose, a method is proposed for indicating the completion of an LTM cell change while supporting a downlink SPS (semi-persistent scheduling) operation and an uplink Configured Grant operation.

[0094] Figure 5 illustrates the downlink SPS (semi-persistent scheduling) operation and the uplink Configured Grant operation applicable to the present disclosure. Figure 5 describes the overall operation methods of DL SPS, UL Type 1 CG, and UL Type 2 CG.

[0095] In the case of DL SPS (5-05), in the case where there is occurrence of periodic DL data such as voice (data is not transmitted continuously but at intervals), the RRC configuration is used to set the period, HARQ process ID, related PUCCH (physical uplink control channel) resources, MCS (modulation and coding scheme) values, etc. in advance, and the activation / deactivation is indicated through DCI (downlink control information) format 1 (downlink control signal). Refer to the SPS configuration in Table 1 below. SPS can be set in only one cell per cell group, and SPS can be set in multiple BWPs of one cell, but only one SPS can be activated at a time. In other words, only the SPS within the activated BWP is activated.

[0096] [Table 1]

[0097]

[0098] The base station (5-10) can transmit DCI (DCI format 1_0 or 1_1) to the terminal (5-15) to activate the corresponding SPS resource according to the SPS setting provided to the terminal (5-15) via RRC. In step 5-20, the base station (5-10) transmits PDCCH (DCI: DCI format 1_0 or 1_1) addressed with CS-RNTI (configured scheduling-radio network temporary identifier) ​​to the terminal (5-15), and at this time, the NDI (new data indicator) field in the DCI is set to 0 (indicating initial transmission) to indicate activation of DL SPS. The terminal (5-15) that receives the DCI receives DL data periodically transmitted as DL SPS resources according to the DCI received in step 5-25 through a PDSCH (physical downlink shared channel) channel, and processes the received DL data. Thereafter, the base station (5-10) transmits the PDCCH (DCI: DCI format 1_0 or 1_1) addressed with CS-RNTI to the terminal (5-15) in step 5-30, and at this time, the NDI field in the DCI is set to 0 (indicating initial transmission) to indicate deactivation of DL SPS. The terminal (5-15) that has been instructed to deactivate DL SPS through the DCI in step 5-35 clears the configured DL grant and transmits a HARQ ACK to the base station notifying that the DCI has been received (5-40).

[0099] For reference, the settings in DCI for DL ​​SPS activation and deactivation are performed in the manner indicated in Tables 2 and 3 below. Table 2 corresponds to the settings for DL ​​SPS or UL type 2 CG activation, and Table 3 corresponds to the settings for DL ​​SPS or UL type 2 CG deactivation.

[0100] [Table 2]

[0101]

[0102] [Table 3]

[0103]

[0104] UL Configured grants (CGs) are categorized into two types based on their activation method. First, there is Type 1 CG, which provides all information for uplink transmission through RRC configuration, and the UE initiates the corresponding UL CG transmission immediately upon RRC reception. Second, there is Type 2 CG, which provides information for uplink transmission through RRC configuration, and performs activation and deactivation instructions through separate DCIs, allowing the base station to control transmission.

[0105] The RRC settings related to UL CG can be referred to the settings in Table 4 below. The RRC settings in Table 4 include common settings including the period, repetition count, HARQ process number, etc. for Type 1 or Type 2 CG, as well as time offset information and time / frequency domain resource information exclusive to Type 1 CG.

[0106] [Table 4]

[0107]

[0108] For UL Type 2 CG (5-50), it not only supports the occurrence of periodic DL data such as voice (data is not transmitted continuously but at intervals), but also is used for URLLC-related data processing, and its activation and deactivation can be controlled in the network through DCI (DCI format 0_0 / 0_1), so it has high versatility. Multiple CGs can be set for each serving cell / BWP, but only one Type of CG can be activated at a time. In other words, only the CG within the activated BWP is activated.

[0109] The base station (5-55) can transmit DCI (DCI format 0_0 or 0_1) to the terminal (5-60) to activate the corresponding UL Type 2 CG resource according to the UL CG setting provided to the terminal (5-60) via RRC. In step 5-65, the base station (5-55) transmits PDCCH (DCI: DCI format 0_0 or 0_1) addressed with CS-RNTI to the terminal (5-60), and at this time, the NDI field in the DCI is set to 0 (indicating initial transmission) to indicate activation of the UL Type 2 CG. The terminal (5-60) receiving this triggers the transmission of a CG confirmation MAC CE (medium access control control element) in step 5-70 to indicate that the DCI received in step 5-65 has been successfully received, and transmits data including the CG confirmation MAC CE (LCID 55) to the base station (5-55) in step 5-75. The MAC CE is used to indicate to the base station (5-55) that the terminal (5-60) will now perform UL CG transmission.

[0110] The terminal (5-60) can perform uplink transmission (if there is data to be transmitted) through the PUSCH with the configured periodic UL CG resources (5-80). Thereafter, the base station (5-55) transmits the PDCCH (DCI: DCI format 0_0 or 0_1) addressed with the CS-RNTI to the terminal (5-60) in step 5-85, and at this time, the NDI field in the DCI is set to 0 (indicating initial transmission) to indicate deactivation of the UL Type 2 CG. The terminal (5-60), which has been instructed to deactivate the UL Type 2 CG through the DCI in step 5-90, triggers transmission of a CG confirmation MAC CE indicating that the corresponding DCI has been successfully received, and transmits data including the corresponding CG confirmation MAC CE (LCID 55) to the base station (5-55) in step 5-95.

[0111] For reference, the settings in DCI for activating and deactivating UL Type 2 CG can be performed in the manner indicated in Table 2 and Table 3.

[0112] FIGS. 6a and 6b are drawings illustrating an embodiment applicable to the present disclosure, in which an LTM RACH-less cell change is performed, and an overall procedure for supporting an operation of determining handover completion in a target cell after the LTM RACH-less cell change is performed and performing periodic transmission without interruption. Hereinafter, in various embodiments of the present disclosure, FIGS. 6a and 6b will be referred to as FIG. 6.

[0113] The terminal (6-01) receives system information (6-15) from cell 1 (6-02) in the camp-on state (6-10) and performs a transition procedure to the connected state (6-20). Thereafter, the serving cell (6-02) requests the terminal capability (using a UE capability enquiry message) from the terminal (6-01), and the terminal (6-01) receives the terminal capability (using a UE capability information message) according to the request of the base station (6-02) and transmits it to the base station (6-02) (6-25). The terminal capability may include information indicating whether L1 / L2-based inter-cell beam changing / management and handover are supported, and further, the terminal capability may include information indicating whether an operation for pre-aligning uplink synchronization for candidate target cells prior to handover can be supported. The terminal (6-01) transmits the terminal capability through at least one of signaling of terminal-specific capability, band-specific capability, or band combination-specific capability.

[0114] The serving cell (6-02) can request (6-30) the necessary configuration information when the terminal (6-01) performs beam change and handover based on L1 / L2 to the neighboring cells (6-03, 6-04) that support L1 / L2-based mobility. The neighboring cells (6-03, 6-04) include the relevant configuration information in a response message to the request and transmit it to the serving cell (6-02) (6-35). The above-mentioned procedures 6-30 and 6-35 are used to request and transmit the pre-configuration-related settings of cells related to L1 / L2 inter-cell beam change and handover (LTM) through inter-node RRC messages or Xn, F1 interfaces. In terms of network implementation, this can be omitted when cell 1 (6-02) and neighboring cells (6-03, 6-04) exist within one DU (intra-DU scenario). When inter-cell beam change and handover are instructed by L1 / L2 based signaling, the terminal (6-01) applies the settings for the cell to which the pre-configured handover is instructed. That is, in step 6-40, the RRC structure for supporting L1 / L2 inter-cell beam change (management) and handover operations, especially pre-configuration for candidate neighboring cells, is provided, and in step 6-40, the serving cell can transmit common / dedicate configuration information to be applied after L1 / L2 based movement (beam change and handover) to neighboring cells (6-03, 6-04) is instructed to the terminal (6-01). That is, since the terminal (6-01) must transmit all the settings of the corresponding cell to be applied after the handover in advance, the ServingCellID or candidateCellID (cell ID associated with PCI), the configuration information corresponding to ServingCellConfigCommon and ServingCellConfig, or the settings for the Cell group (MAC, RLC, etc.) may also be provided in advance.The corresponding configuration information can be provided to the terminal (6-01) in the form of pre-configuration in the RRC configuration, and can include configuration information for multiple cells and cell groups. In addition, the configuration is characterized by including all configuration information (cell configuration, bearer configuration, security key, measurement configuration, etc.) that is applied when the terminal (6-01) moves (handovers) to the corresponding cell. In addition, the configuration includes unified TCI state configuration and L1 measurement and report-related configurations for LTM candidate cells. For reference, the DL SPS / UL CG-related configurations considered in the present disclosure can be provided for each LTM candidate cell, and the CS-RNTI can also be transmitted for each LTM candidate cell. In addition, when an LTM RACH-less cell change occurs for each LTM candidate cell, the Type 1 CG configuration dedicated to LTM used for UL first data transmission is also transmitted. For details on the configuration, refer to the description of FIG. 5.

[0115] In addition to the RRC configuration information for the above-described basic candidate target cells, the present invention provides configurations related to performing uplink synchronization for the candidate target cells prior to handover. In the following embodiments of the present disclosure, terms such as early TA (Timing Advance), early RACH, pre-uplink synchronization acquisition, or pre-random access are used interchangeably. In addition, the configurations may be configured with the following values. Although the present disclosure uses the term early TA, it may be an operation for aligning uplink synchronization with early random access or an operation similar to early random access. In particular, the early TA operation may be defined as an operation for transmitting a preset CBRA (contention-based random access) or CFRA (contention-free random access) preamble for each LTM candidate cell, and msg1 transmission, which will be described in detail below. In the future, if improved, it may be extended to an operation including receiving msg2 (RAR; random access response) in response to the msg1 signal. The RAR signal may follow an existing RAR signal or may be a modified RAR.

[0116] - Method for setting early TA operation for LTM candidate target cells

[0117] ■ Provides CBRA (contention-based random access) and CFRA (contention-free random access) preamble settings required for early TA for each LTM candidate cell (one or more preamble indexes / PO indexes / SSB indexes)

[0118] ■ That is, common RACH resources or dedicated RACH resources can be configured and used for each LTM candidate cell. The configuration can be provided by the source cell as an LTM configuration, or can be included in the candidate cell configuration.

[0119] In step 6-45, the terminal (6-01) performs measurement on L1 measurement resources for LTM according to the RRC settings received in step 6-40, and reports the measurement results to the base station (serving cell 6-02). The L1 measurement report may be a measurement value for LTM candidate cells, and is performed according to a method (periodic reporting, aperiodic reporting, one-time reporting) set by the base station (6-02). The serving cell (6-02) transmits a message to the LTM candidate cells (6-03, 6-04) notifying them that the LTM settings have been delivered to the terminal and requesting whether to perform early TA (step 6-50), and may receive response messages from the LTM candidate cells (6-03, 6-04). Each LTM candidate cell (6-03, 6-04) can determine whether TA with the terminal (6-01) is valid, whether RACH-less handover is performed, etc., and transmit a response message to the source cell (6-02). Steps 6-50 and 6-55 may be omitted, in which case the source cell (6-02) can determine whether early TA is necessary and instruct the terminal (6-01) accordingly without a separate request and response procedure. In step 6-60, the source cell (6-02) transmits a PDCCH order to the terminal (6-01) according to the determination of the need for early TA to specific LTM candidate cells. The PDCCH order may include an indicator indicating an LTM candidate cell (an LTM candidate cell is set and an index is provided in the RRC configuration and used in the PDCCH order). For example, the reserved bits existing in the existing DCI format 1_0 may be used to indicate an LTM candidate cell index. The terminal (6-01) that has received the above PDCCH order performs random access preamble transmission for early TA to LTM candidate cells indicated in the PDCCH order (6-65).In step 6-40, CFRA resources for early TA for LTM candidate cells are set, and the terminal (6-01) uses the resources to transmit a random access preamble to the LTM candidate cell indicated in the PDCCH order. The early TA procedure in the present disclosure is characterized by only transmitting msg1 (random access preamble) and not receiving msg2 (RAR). Note that, since there may be no operation of receiving RAR in the early TA procedure, there is no operation of the terminal acquiring TA according to the early TA performance and managing the TA value according to a timer within the terminal. In step 6-70, the LTM candidate cell (the target cell where early TA is performed) calculates a TA value between the terminal (6-01) and the corresponding cell based on the RACH preamble received from the terminal (6-01), and stores and manages it internally. Afterwards, the validity of the TA value can be determined (using its own timer or receiving terminal measurement values) and information about the validity can be provided to the source cell (6-02). For example, the LTM candidate cell can transmit information indicating that the uplink TA for the terminal (6-01) is not valid to the source cell (6-02) in step 6-75 to trigger the early TA again. In the above, the internal timer of the base station for determining the validity can be operated internally in the source cell (6-02) and the LTM candidate cell (the target cell where the early TA is performed), and for this purpose, the timer value can be shared with each other or set and transmitted. In addition, instead of the above 6-70 / 6-75 procedure, the source cell (6-02) can determine the validity of the TA value (using its own timer or receiving terminal measurement values) and trigger the early TA again. The inter-node procedure for early TA between the source cell (6-02) and LTM candidate cells (6-03, 6-04) is summarized as follows.

[0120] Option 1: Manage the validity of the TA value for early TA in the LTM candidate cell. That is, if the early TA value is determined to be invalid, re-request the PDCCH order for early TA from the source cell.

[0121] - Option 2: The LTM candidate cell transmits the TA valid timer value together with a valid TA value to the source cell. If the timer expires in the source cell and a new valid TA value is not received from the LTM candidate cell, a PDCCH order for early TA for the LTM candidate cell is triggered again, or if the LTM operation needs to be instructed to the UE, an LTM MAC CE is transmitted to instruct a handover. In this case, the valid TA value is not included (the TA value inclusion indicator or the RACH-less indicator is not included) and the UE is instructed to perform random access during LTM.

[0122] In step 6-80, the terminal (6-01) measures L1 measurement resources according to the RRC settings for LTM and reports the measurement results to the base station (source cell; 6-02). In step 6-85, the serving cell (6-02) can decide to change cells (handover) of the terminal (6-01) based on the received L1 measurement results, and instructs handover to the target cell (TRP 2-Cell 2, 6-03) through the MAC CE indicating LTM. The LTM MAC CE includes at least one of the following information.

[0123] - Target cell index where LTM is performed (candidate cell ID; candidate cell configuration ID)

[0124] - Active BWP ID in target cell

[0125] - Indicator indicating whether to perform SCell activation (carrier aggregation) simultaneously when performing LTM (1 bit or information on the SCell to be activated)

[0126] - UL grant information (resources for data transmission after LTM in the target cell, for example, resources used to transmit the RRCReconfigurationComplete message)

[0127] - Beam information used when transmitting in the target cell (TCI state; unified TCI state information)

[0128] - C-RNTI (cell-radio network temporary identifier) ​​used by the target cell

[0129] - RACH-less handover and uplink TA information

[0130] -> Timing Advance Command information: The source cell can transmit a valid TA value to the LTM MAC CE to instruct the UE to perform a RACH-less handover to the target cell.

[0131] ->> Option 1: 12 bits TA value as included in existing RAR

[0132] ->> Option 2: Relative TA values ​​and reference cell and TA information

[0133] ->>> Reference Cell and TA Information: Unless otherwise specified, the cell to which the PTAG (primary timing advance group) applies becomes the reference, and the PTAG value becomes the TA reference value. Alternatively, a specific cell or TAG (timing advance group) ID can be designated as the reference cell and reference TA value.

[0134] ->>> Relative TA value: TA value relative to the reference TA value for the reference cell and TAG (6 bits of TA value like the Timing Advance Command in the existing 'Timing Advance Command MAC CE')

[0135] -> TA value presence indicator (or RACH / RACH-less indicator): This information can be conveyed as 1 bit, or it can be implicitly indicated through another field. That is, it can be omitted.

[0136] ->> Example 1: If the above TA value is provided in the MAC CE, the terminal performs a RACH-less handover to the target cell by applying the TA value even if there is no separate RACH / RACH-less indicator. In this case, the indicator indicating whether a TA value exists or whether a TA value exists serves as the RACH / RACH-less indicator.

[0137] ->>> When specifying 0 as the TA value compared to the current reference cell and TAG, the TA value of the corresponding TAG (e.g. PTAG) is applied as is.

[0138] ->>> When using an absolute TA value when printing a TA value, the TA value of the current TAG (e.g. PTAG) is printed again and transmitted.

[0139] ->> Example 2: The TA value presence indicator and the RACH / RACH-less indicator can be indicated separately. In this case, the TA value is printed, but it can be used in cases such as indicating RACH.

[0140] In step 6-85, when the terminal (6-01) receives the LTM MAC CE, the terminal (6-01) performs a handover to the target cell according to the information included in the LTM MAC CE, changes the beam to the indicated beam, and performs data transmission and reception through the corresponding beam. In step 6-85, whether to perform random access to the target cell (TRP 2-Cell 2, 6-03) is determined by omitting the random access operation when performing a handover to the target cell according to the TA value indicated in the LTM MAC CE and the valid TA value inclusion indicator (RACH-less handover indicator) and applying uplink synchronization to the corresponding target cell. In the present disclosure, an additional idea is specifically proposed for the case where an LTM RACH-less cell change occurs in the corresponding step. In step 6-85, the terminal (6-01) attempts a handover to the target cell and simultaneously starts a handover operation timer to the LTM target cell. This may use the existing T304 timer, which is a handover operation timer, or a new timer dedicated to LTM (e.g., T3XX) may be introduced. The timer setting may be transmitted when the LTM setting is provided as an RRC setting, and the timer value may be individually set in each candidate LTM cell setting (in this case, set in the SpCell setting of the candidate LTM cell setting), or may be set to be commonly applied to all LTM candidate cells. If the LTM handover is terminated while the T3XX timer is running, the terminal (6-01) determines that the T3XX timer is stopped and the handover is successfully completed. Here, the case where the LTM handover is terminated may be when the terminal (6-01) transmits (6-95) the first uplink transmission (e.g., RRCReconfigurationComplete message) to the LTM target cell and receives (6-100) a response to the uplink transmission (RRC reconfiguration complete message). The response method may be one of the following methods.

[0141] First, in step 6-95, after the terminal (6-01) instructs to change to an LTM RACH-less cell, the resource for transmitting the first uplink data to the target cell (6-03) is set as a Type 1 CG resource for each candidate cell in step 6-40, and the terminal (6-01) can select and transmit the first resource that the terminal can transmit from among the resources. The following method is possible for indicating the completion of the LTM RACH-less cell change by transmitting a response to the LTM RACH-less cell change in step 6-100. The following method is one of the main features proposed in the present disclosure.

[0142] - Option 1: C-RNTI addressed PDCCH reception (may include UL or DL ​​grant, UE Contention Resolution identify MAC CE, etc., or padding)

[0143] - Option 2: Receiving CS-RNTI addressed PDCCH that activates DL SPS resources

[0144] - Option 3: Receiving CS-RNTI addressed PDCCH that activates UL Type 2 CG resources

[0145] - Option 4: Receiving v2x-SPS-RNTI addressed PDCCH that activates V2X transmission (e.g. SPS)

[0146] - Option 5: Receiving G-RNTI (group-radio network temporary identifier) ​​addressed PDCCH for MBS (multicast broadcast service) transmission, etc.

[0147] Alternatively, terminal-specific data transmission / reception related RNTI values ​​introduced in the future may be included in addition to the above.

[0148] In particular, the above options 2 and 3 may be intended to reduce the interruption time so that voice service can be supported even after the LTM RACH-less cell change when the terminal (6-01) is using the voice service before the LTM RACH-less cell change and the cell change is performed. If only the method in option 1 is used, PDCCH transmission may be delayed due to the absence of data other than voice, which may cause performance degradation. Therefore, at least when the terminal (6-01) monitors the PDCCH after the LTM RACH-less cell change and receives a PDCCH expressed by a valid RNTI listed above, it can be determined that the LTM RACH-less cell change is complete. When the terminal (6-01) determines that the LTM RACH-less cell change is complete, it terminates the connection with the previous serving cell (6-02), i.e., releases the configuration with the previous serving cell (6-02). Then, the settings of the target cell (6-03) are applied, and data transmission and reception are performed through scheduled resources (6-105).

[0149] If the LTM handover is not completed until the corresponding T3XX timer expires as described above, a timer expiration operation is performed for each cell group (MN or SN). That is, when the T3XX expires for the MCG (master cell group), the RRC re-establishment procedure is performed for the MCG, and when the T3XX expires for the SCG (secondary cell group), the network is notified that an LTM failure has occurred in the SCG and the SCG failure procedure is performed.

[0150] If, after the LTM MAC CE cell change, the TAT (timing alignment timer) can be operated (or operated when the LTM MAC CE is received), and the timer expires, in step 6-110, the terminal determines that the uplink synchronization with the target cell is not aligned and performs the operations when the existing uplink synchronization is not aligned, such as releasing PUCCH / SRS (sounding reference signal), and flushing the HARQ buffer. Refer to the contents of Table 5 below.

[0151] [Table 5]

[0152]

[0153] For reference, since the target cell (6-03) can be notified of the expiration of the timer, etc., it can trigger random access to the terminal (6-01) again in PDCCH order to re-synchronize the terminal's uplink if necessary.

[0154] In addition to the overall LTM RACH-less cell change procedure and operation completion described above and the method for transmitting and receiving data in the target cell, additional ideas proposed in the present disclosure are described below.

[0155] First, the LTM Type 1 CG (6-115) configuration used for the first uplink transmission from the target cell (6-03) after the LTM RACH-less cell change and the Type 1 CG (6-120) configuration for data transmission used for existing data transmission can be provided simultaneously. This can be configured within the LTM candidate cell configuration in step 6-40, and the following restrictions are required to make the operation clear.

[0156] - Type 1 CG (6-120) for data transmission used for existing data transmission can only use resources after RACH-less LTM completion.

[0157] - This is to prevent collision with the LTM Type 1 CG transmission used for the first uplink transmission in the target cell after LTM RACH-less cell change.

[0158] Secondly, we define various scenarios to support voice services in LTM RACH-less cell changes.

[0159] - Scenario 1

[0160] -> LTM Type 1 CG resources continue to be used for uplink transmission even after changing to an LTM RACH-less cell.

[0161] -> Downlink DL SPS resources are used according to the base station activation signal.

[0162] - Scenario 2

[0163] -> For uplink transmission, existing Type 1 CG resources are used after changing to LTM RACH-less cells.

[0164] -> Downlink DL SPS resources are used according to the base station activation signal.

[0165] - Scenario 3

[0166] -> For uplink transmission, existing Type 2 CG resources are used according to the base station activation signal.

[0167] -> Downlink DL SPS resources are used according to the base station activation signal.

[0168] Thirdly, we define the behavior for the case where the Type 1 CG transmission dedicated to LTM fails. That is, if the first uplink data containing the HO (handover) Complete message is sent as a Type 1 CG dedicated to LTM and the base station fails to decode it, the retransmission resource may be allocated with CS-RNTI (or C-RNTI). In this case (retransmission resource allocation), it may be considered as LTM complete, or it may be excluded and only the above LTM complete options may be considered as LTM completion.

[0169] The fourth behavior is related to allowing automatic retransmission for Type 1 CG transmissions dedicated to LTM. If a Type 1 CG for LTM RACH-less cell change Complete transmission performs automatic retransmission, ConfiguredGrantTimer may not be set. Note that if ConfiguredGrantTimer is set and running, the CG is prohibited from using the corresponding HARQ process, which may delay the time until HO Complete. Otherwise, the purpose of ConfiguredGrantTimer can be changed so that, for Type 1 CGs for LTM RACH-less, automatic retransmission is performed when ConfiguredGrantTimer is running. In addition, although the behavior for cases where there is no response to HO Complete until the Automatic Retransmission period ends is defined, restrictions can be added to prevent this event from occurring. If the behavior of performing automatic retransmission until the HO Failure Timer (T304) expires is defined, the base station can set ConfiguredGrantTimer to a value equal to or greater than the T304 timer.

[0170] Fifthly, HO Complete is sent to Type 1 CG by RACH-less, and if the base station determines that RACH is necessary, an action may be added for the base station to indicate RACH.

[0171] FIG. 7 is a diagram illustrating terminal operation from the entire terminal operation of performing L1 / L2 inter-cell handover to completion of LTM RACH-less cell change, which is applied to embodiments of the present disclosure.

[0172] In step 7-05, a connected terminal can receive common / dedicated configuration information for neighboring cells that are applied after L1 / L2-based movement is indicated by an RRC reconfiguration message from the serving cell. For detailed configuration methods and details, refer to Drawing 6. In particular, the configuration includes configuration information for LTM candidate cells, and may include early TA and LTM Type 1 CG configurations, DL SPS, and Type 1 / 2 CG configurations.

[0173] The terminal that has received the setting receives a PDCCH order indicating an early TA (early RACH) operation in steps 7-10, and the PDCCH order may include an index for an LTM candidate cell that should perform early TA. The terminal transmits (msg1) a random access preamble to the indicated LTM candidate cell through a CFRA resource configured for early TA. There is no RAR, which is a response to the random access preamble transmitted in the step. That is, the LTM candidate cell synchronizes the uplink for the cell by receiving the random access preamble transmitted by the terminal through the configured CRFA resource, and stores and manages the synchronization value for the TAG (timing advance group) to which the cell belongs with the synchronized synchronization. For reference, since the terminal does not receive the TA value or whether the TA is valid through a separate signal from the LTM candidate cells prior to receiving the LTM MAC CE through the above operation, there is no separate terminal action. In steps 7-15, the terminal performs L1 resource measurement and reporting according to the L1 measurement and reporting settings for the configured LTM candidate cells. For detailed operations, refer to the relevant contents of FIG. 6 of the present disclosure.

[0174] In step 7-20, the terminal receives the LTM MAC CE and performs different operations thereafter depending on what values ​​are indicated in the corresponding signaling. In particular, the operation is different depending on whether the LTM MAC CE includes an indicator indicating whether to perform random access (RACH-less handover indication) or a valid TA value (7-25). If the LTM MAC CE includes at least one of a valid TA value or a RACH-less handover indicator, the terminal applies the indicated TA value to the target cell indicated in step 7-30 and performs a RACH-less handover operation to the target cell. At this time, a timer is started and the corresponding cell settings preset by RRC are applied. For reference, the timer is started and the detailed LTM MAC CE signaling information may be operations related to T3XX (T304-like timer) and T3YY (TA validity determination timer applied in the LTM target cell) described in FIG. 6, and the detailed operations refer to FIG. 6. In this case, the UE transmits a valid TA value for the target cell where the handover is performed to the LTM MAC CE, and if the corresponding TA value is applied, the random access process can be omitted, thereby significantly reducing the uplink interruption time. In addition, for example, the current serving cell and the target cell may have the same uplink synchronization, and even if they belong to the same DU, this can be indicated by marking the corresponding TA value as 0 or setting the RACH-less handover indicator to true. In other words, the operation can be indicated on the premise that the base station has the same synchronization for the target cell and the serving cell, and in this case, the UE applies the uplink synchronization in the serving cell as is. Alternatively, a specific serving cell and TAG index can be transmitted together to indicate the reference cell and TAG.

[0175] In steps 7-35, when the uplink TA timer (T3YY) expires, the UE performs the timer expiration operation described in 6. That is, the UE performs operations such as PUCCH / SRS release and HARQ buffer flush. Alternatively, in this step, a random access may be triggered to obtain new uplink synchronization by receiving a PDCCH order from the base station before the uplink TA timer (T3YY) expires. In addition, in steps 7-30, the UE performs the first uplink transmission including the RRCReconfigurationComplete message to indicate the completion of the handover to the target cell according to the LTM Type 1 CG configuration set as the target cell. The LTM Type 1 CG resource may be used for the first uplink transmission after changing to an LTM RACH-less cell and may not be used thereafter. Alternatively, the resource may continue to be used even after the first uplink transmission after changing to an LTM RACH-less cell. If continued use is possible, it is possible until the resource is released by a separate base station configuration. As a feature of the present disclosure, the terminal can receive a PDCCH addressed to a predefined RNTI from the base station in response to the handover completion instruction for the target cell in step 7-30, and in this case, the completion of the LTM RACH-less cell change for the target cell can be confirmed (step 7-35). At least one value among the options proposed in FIG. 6 can be used as the RNTI. After the LTM RACH-less cell change is completed, the terminal applies the target cell configuration, releases the previous cell configuration, and performs UL / DL transmission scheduled on the PDCCH received from the base station.

[0176] In step 7-25, if the LTM MAC CE from the base station does not include a valid TA value or a RACH-less handover indicator, the terminal performs a random access operation to the indicated target cell and performs a handover (7-40). In addition, when handing over to the target cell, the preset settings for the cell from the base station are applied. Since random access is also performed in this operation, the terminal can obtain a valid TA value after the random access to the target cell (via RAR or TA command MAC CE) and performs an operation to maintain the value according to the TA timer preset in RRC. In addition, in step 7-45, the terminal performs an existing uplink TA timer expiration operation when the uplink TA timer expires. That is, the terminal performs operations such as releasing PUCCH / SRS and flushing the HARQ buffer. Alternatively, in step 7-45, the terminal may receive a PDCCH order from the base station before the uplink TA timer expires, and a random access may be triggered in the terminal to obtain new uplink synchronization.

[0177] FIG. 8 is a diagram illustrating base station operations applied to embodiments of the present disclosure.

[0178] In step 8-05, the base station provides system information to the terminal, and in step 8-10, the common / dedicate configuration information for the neighboring cells applied after L1 / L2-based movement is instructed from the serving cell through an RRC reconfiguration message to the terminal in the connected state is transmitted. For detailed configuration method and contents, refer to the contents of Drawing 6. In particular, the present disclosure is characterized in that, among the configuration information for cells to which L1 / L2 handover is applied in the corresponding configuration, it includes early TA-related configuration and instruction for performing uplink synchronization for candidate cells in advance, LTM Type 1 CG configuration, DL SPS, Type 1 / 2 CG configuration, etc.

[0179] At this stage, the base station can perform coordination with the surrounding LTM candidate cells regarding LTM configuration and early TA indication. This can be performed via Xn or F1 interface and inter-node RRC messages (CG-ConfigInfo, CG-Config). Then, at steps 8-15, the source base station (serving cell) transmits a PDCCH order that triggers the early TA procedure to the UE for the LTM candidate cells that require early TA. That is, the base station includes the LTM candidate cell index in the PDCCH order and instructs the UE to transmit a random access preamble for early TA to the corresponding target cell. The random access preamble resource used at this time is the CFRA resource set for the LTM candidate cells at steps 8-10. According to the PDCCH order indicated at the above step, each LTM candidate cell receives a random access preamble from the UE, calculates an uplink TA based on the random access preamble, and transmits the TA value to the serving cell. That is, in steps 8-20, the base station (serving cell) receives a valid TA value with the terminal from each LTM candidate cell and stores and manages it.

[0180] In steps 8-25, the base station receives L1 measurement values ​​from the terminal. The measurement values ​​may be reports on non-serving cells supporting L1 / L2-based mobility, i.e., LTM candidate cells. The serving cell can determine whether to change the beam of the terminal and perform a handover based on the received measurement results. If it determines that a handover and a change to a specific beam of a neighboring cell are necessary rather than a specific beam of the serving cell, it instructs the terminal to change the cell and beam through LTM MAC CE in step 8-30. In steps 8-30, the serving cell can instruct whether to perform random access to the cell where the handover is to occur, whether to transmit a valid TA value, and whether to change the beam, etc., through L1 / L2 signaling. If a handover is instructed, the serving cell performs the handover procedure, and when the handover with the target cell is completed in steps 8-30, it deletes the terminal context and releases the connection. In the above, the measurement value for determining whether to perform a handover is an L1 measurement. Additionally, steps 8-15 and 8-20 can be triggered as needed. That is, if the base station determines that the TA value with the terminal is invalid, it can trigger a new TA procedure to reacquire the TA. Conversely, the base station may omit the early TA procedure for the purpose of triggering random access even if the TA value is determined to be invalid for a specific LTM candidate cell. In this case, the base station can instruct the terminal to perform an LTM handover through signaling, such as not including a valid TA value in the LTM MAC CE and indicating the RACH-less handover indicator as false.

[0181] In step 8-35, the base station receives the first uplink data (including RRCReconfigurationComplete) from the terminal through the preset LTM Type 1 CG resource. In step 8-35, the base station transmits a PDCCH addressed with an RNTI associated with the data to be scheduled to the terminal in response to the LTM cell switch completion received from the terminal. The control signal is transmitted as a DCI and may or may not include scheduling information and may include other MAC CEs and padding. This is used for the purpose of confirming the LTM cell switch completion, and the terminal receiving it can be informed that the LTM RACH-less cell change is complete. Thereafter, the base station and the terminal perform data transmission and reception according to the indicated scheduling.

[0182] Figure 9 is a drawing showing the configuration of a terminal to which the present disclosure is applied.

[0183] Referring to the above drawing 9, the terminal includes an RF (radio frequency) processing unit (9-10), a baseband processing unit (9-20), a storage unit (9-30), and a control unit (9-40).

[0184] The RF processing unit (9-10) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (9-10) up-converts the baseband signal provided from the baseband processing unit (9-20) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (9-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In the drawing, only one antenna is shown, but the terminal may be equipped with multiple antennas. In addition, the RF processing unit (9-10) may include multiple RF chains. Furthermore, the RF processing unit (9-10) may perform beamforming. For the above beamforming, the RF processing unit (9-10) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit can perform MIMO, and can receive multiple layers when performing the MIMO operation.

[0185] The baseband processing unit (9-20) above performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (9-20) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (9-20) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (9-10). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (9-20) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through an inverse fast Fourier transform (IFFT) operation and a cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit (9-20) divides the baseband signal provided from the RF processing unit (9-10) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform) operation, and then restores the received bit string through demodulation and decoding.

[0186] The baseband processing unit (9-20) and the RF processing unit (9-10) transmit and receive signals as described above. Accordingly, the baseband processing unit (9-20) and the RF processing unit (9-10) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (9-20) and the RF processing unit (9-10) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (9-20) and the RF processing unit (9-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. Additionally, the different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and a millimeter wave (mm wave) (e.g., 60GHz) band.

[0187] The storage unit (9-30) stores data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (9-30) can store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit (9-30) provides the stored data at the request of the control unit (9-40).

[0188] The control unit (9-40) controls the overall operations of the terminal. For example, the control unit (9-40) transmits and receives signals through the baseband processing unit (9-20) and the RF processing unit (9-10). In addition, the control unit (9-40) records and reads data in the storage unit (9-40). For this purpose, the control unit (9-40) may include at least one processor. For example, the control unit (9-40) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs. The control unit (9-40) may control the operations of the terminal according to various embodiments of the present disclosure. For example, the control unit (9-40) may perform an operation of determining and controlling a cell change operation triggered by L1 / L2 according to an embodiment of the present disclosure and the completion of the cell change.

[0189] Fig. 10 is a block diagram showing the configuration of a base station according to the present disclosure.

[0190] As shown in the above drawing, the base station is configured to include an RF processing unit (10-10), a baseband processing unit (10-20), a backhaul communication unit (10-30), a storage unit (10-40), and a control unit (10-50).

[0191] The RF processing unit (10-10) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (10-10) up-converts the baseband signal provided from the baseband processing unit (10-20) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (10-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In the drawing, only one antenna is shown, but the first access node may have multiple antennas. In addition, the RF processing unit (10-10) may include multiple RF chains. Furthermore, the RF processing unit (10-10) may perform beamforming. For the above beamforming, the RF processing unit (10-10) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit can perform a downlink MIMO operation by transmitting one or more layers.

[0192] The baseband processing unit (10-20) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (10-20) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (10-20) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (10-10). For example, in the case of OFDM, when transmitting data, the baseband processing unit (10-20) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (10-20) divides the baseband signal provided from the RF processing unit (10-10) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operation, and then restores the received bit string through demodulation and decoding. The baseband processing unit (10-20) and the RF processing unit (10-10) transmit and receive signals as described above. Accordingly, the baseband processing unit (10-20) and the RF processing unit (10-10) may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0193] The above backhaul communication unit (10-30) provides an interface for performing communication with other nodes within the network. That is, the backhaul communication unit (10-30) converts a bit string transmitted from the main base station to another node, such as an auxiliary base station or core network, into a physical signal, and converts a physical signal received from the other node into a bit string.

[0194] The storage unit (10-40) stores data such as basic programs, application programs, and setting information for the operation of the main base station. In particular, the storage unit (10-40) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (10-40) can store information that serves as a judgment criterion for whether to provide or terminate multiple connections to a terminal. In addition, the storage unit (10-40) provides the stored data at the request of the control unit (10-50).

[0195] The control unit (10-50) controls the overall operations of the base station. For example, the control unit (10-50) transmits and receives signals through the baseband processing unit (10-20) and the RF processing unit (10-10) or through the backhaul communication unit (10-30). In addition, the control unit (10-50) records and reads data in the storage unit (10-40). For this purpose, the control unit (10-50) may include at least one processor. The control unit (10-50) may control the operations of the base station according to various embodiments of the present disclosure. For example, the control unit (10-50) may control operations related to L1 / L2 trigger cell changes, and may perform operations for determining the completion of cell changes proposed in the present disclosure.

[0196] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0197] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present disclosure.

[0198] These programs (software modules, software) may be stored in a non-volatile memory including random access memory, flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0199] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0200] In the specific embodiments of the present disclosure described above, components included in the present disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0201] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples to easily explain the technical contents of the present disclosure and to help understand the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, the respective embodiments may be combined and operated with each other as needed. For example, parts of one embodiment of the present disclosure and another embodiment may be combined with each other to operate a base station and a terminal. In addition, the embodiments of the present disclosure are applicable to other communication systems, and other modifications based on the technical idea of ​​the embodiments may also be implemented.

Claims

1. In a terminal method in a wireless communication system, A step of receiving a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information from a first cell; A step of transmitting an L1 (layer 1) measurement report to the first cell; A step of receiving a PDCCH (physical downlink control channel) order for early TA (timing advance) from the first cell; A step of transmitting a preamble for the above Early TA to the second cell; A step of receiving an LTM MAC CE (medium access control control element) from the first cell, which instructs handover to the second cell; A step of transmitting a second RRC message to the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE; A step of receiving a third RRC message from the second cell; and A method comprising the step of determining the success of the handover based on the LTM based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

2. In paragraph 1, A method wherein the above RNTI includes a CS-RNTI (configured scheduling-radio network temporary identifier) ​​for DL-SPS (downlink-semi-persistent scheduling) or a CS-RNTI for UL (uplink) type 2 CG.

3. In paragraph 1, If the LTM MAC CE includes a TA value, the second RRC message is transmitted based on the TA value. A method for performing random access to the second cell if the LTM MAC CE does not include a TA value.

4. In paragraph 1, If the handover is judged as successful based on the above LTM: Transmit the first uplink data based on the LTM type 1 CG resource, or A method for transmitting the first uplink data based on type 1 CG resources, wherein the type 1 CG resources have a higher priority than the LTM type 1 CG resources.

5. In a method of a base station in a wireless communication system, A step of transmitting a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information to a terminal through a first cell of the base station; A step of receiving an L1 (layer 1) measurement report from the terminal through the first cell; A step of transmitting a PDCCH (physical downlink control channel) order for early TA (timing advance) to the terminal through the first cell; A step of receiving a preamble for the Early TA from the terminal through the second cell; A step of transmitting an LTM MAC CE (medium access control control element) indicating handover to the second cell to the terminal through the first cell; A step of receiving a second RRC message from the terminal through the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE; and comprising a step of transmitting a third RRC message to the terminal through the second cell; A method for determining the success of a handover based on the LTM based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

6. In paragraph 5, A method wherein the above RNTI includes a CS-RNTI (configured scheduling-radio network temporary identifier) ​​for DL-SPS (downlink-semi-persistent scheduling) or a CS-RNTI for UL (uplink) type 2 CG.

7. In paragraph 5, If the LTM MAC CE includes a TA value, the second RRC message is transmitted based on the TA value. A method for performing random access to the second cell if the LTM MAC CE does not include a TA value.

8. In paragraph 5, If the handover is judged as successful based on the above LTM: Transmit the first uplink data based on the LTM type 1 CG resource, or A method for transmitting the first uplink data based on type 1 CG resources, wherein the type 1 CG resources have a higher priority than the LTM type 1 CG resources.

9. In the terminal of a wireless communication system, Transmitter and receiver; and Including a control unit, The above control unit, Receive a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information from a first cell, Transmits an L1 (layer 1) measurement report to the first cell above, Receive a PDCCH (physical downlink control channel) order for early TA (timing advance) from the first cell, Transmitting a preamble for the above Early TA to the second cell, Receive an LTM MAC CE (medium access control control element) from the first cell, which instructs handover to the second cell; A second RRC message is transmitted to the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE. Receive a third RRC message from the second cell, and A terminal that controls to determine the success of handover based on the LTM based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

10. In paragraph 9, The above RNTI is a terminal including a CS-RNTI (configured scheduling-radio network temporary identifier) ​​for DL-SPS (downlink-semi-persistent scheduling) or a CS-RNTI for UL (uplink) type 2 CG.

11. In paragraph 9, If the LTM MAC CE includes a TA value, the second RRC message is transmitted based on the TA value. A terminal performing random access to the second cell if the TA value is not included in the above LTM MAC CE.

12. In paragraph 9, If the handover is judged as successful based on the above LTM: Transmit the first uplink data based on the LTM type 1 CG resource, or A terminal that transmits the first uplink data based on type 1 CG resources, wherein the type 1 CG resources have a higher priority than the LTM type 1 CG resources.

13. In a base station of a wireless communication system, Transmitter and receiver; and Including a control unit, The above control unit, Transmitting a first RRC (radio resource control) message including LTM (L1 / L2 triggered mobility) related configuration information to a terminal through the first cell of the base station, Receives an L1 (layer 1) measurement report from the terminal through the first cell; Transmitting a PDCCH (physical downlink control channel) order for Early TA (timing advance) to the terminal through the first cell, Receive a preamble for the Early TA from the terminal through the second cell, Transmitting an LTM MAC CE (medium access control control element) instructing handover to the second cell to the terminal through the first cell, Receive a second RRC message from the terminal through the second cell using the LTM type 1 CG (configured grant) resource based on the LTM MAC CE, and Control to transmit a third RRC message to the terminal through the second cell, A base station that determines the success of handover based on the LTM based on an RNTI (radio network temporary identifier) ​​for a PDCCH (physical downlink control channel) corresponding to the third RRC message.

14. In paragraph 13, The above RNTI is a base station including a CS-RNTI (configured scheduling-radio network temporary identifier) ​​for DL-SPS (downlink-semi-persistent scheduling) or a CS-RNTI for UL (uplink) type 2 CG.

15. In paragraph 13, If the LTM MAC CE includes a TA value, the second RRC message is transmitted based on the TA value. A base station performing random access to the second cell if the LTM MAC CE does not include a TA value.

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