Method and device for supporting mobility of user equipment through common target cell configuration in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. Specifically, disclosed are a method and device for supporting mobility of a user equipment through a common target cell configuration. According to an embodiment, a method performed by a user equipment in a wireless communication system may comprise the steps of: receiving, from a base station, common handover configuration information commonly applied to a plurality of handover types for each of a plurality of candidate target cells; receiving, from the base station, additional configuration information additionally used according to at least one handover type among the plurality of handover types; identifying a handover trigger; identifying a handover type for the triggered handover among the plurality of handover types; and performing a procedure according to the identified handover type on the basis of the common handover configuration information and the additional configuration information.

Description

Method and device for supporting terminal mobility through common target cell configuration in a wireless communication system

[0001] The present disclosure relates to the operation of a terminal in a wireless communication system. Specifically, it relates to a method for supporting terminal mobility through common target cell configuration.

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

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

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

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

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

[0008] As described above and with the development of mobile communication systems, various services have become available, and methods for providing these services effectively are required.

[0009] The disclosed embodiment seeks to provide a device and method capable of effectively providing a service in a mobile communication system.

[0010] According to one embodiment of the present disclosure, in a wireless communication system, a method performed by a user equipment may include the steps of: receiving, from a base station, common handover configuration information commonly applied to a plurality of handover types for each of a plurality of candidate target cells; receiving, from the base station, additional configuration information additionally used according to at least one handover type among the plurality of handover types; identifying a trigger for a handover; identifying a handover type for the triggered handover among the plurality of handover types; and performing a procedure according to the identified handover type based on the common handover configuration information and the additional configuration information.

[0011] According to one embodiment of the present disclosure, in a wireless communication system, a method performed by a base station including a serving cell may include the steps of: identifying at least one candidate target cell for a handover of a user equipment; transmitting a handover request message for a handover of the user equipment to the at least one candidate target cell; receiving, from the at least one candidate target cell, common target cell configuration information commonly applied to a plurality of handover types for each of the at least one candidate target cell and additional configuration information additionally used according to at least one handover type among the plurality of handover types; and transmitting the common handover configuration information and the additional configuration information to the user equipment.

[0012] According to one embodiment of the present disclosure, in a user equipment, the terminal may include at least one transceiver, at least one processor communicatively coupled to the at least one transceiver, and at least one memory communicatively coupled to the at least one processor and storing instructions. The above commands may be executed individually or in any combination by the at least one processor, so that the terminal receives, from a base station, common handover configuration information commonly applied to a plurality of handover types for each of a plurality of candidate target cells, receives, from the base station, additional configuration information additionally used according to at least one handover type among the plurality of handover types, identifies a trigger for a handover, identifies a handover type for the triggered handover among the plurality of handover types, and performs a procedure according to the identified handover type based on the common handover configuration information and the additional configuration information.

[0013] According to one embodiment of the present disclosure, in a base station including a serving cell, the base station may include at least one transceiver, at least one processor communicatively coupled to the at least one transceiver, and at least one memory communicatively coupled to the at least one processor and storing instructions. The above commands may be executed individually or in any combination by the at least one processor to cause the base station to identify at least one candidate target cell for handover of a user equipment, transmit a handover request message for handover of the user equipment to the at least one candidate target cell, receive, from the at least one candidate target cell, common target cell configuration information commonly applied to a plurality of handover types for each of the at least one candidate target cell and additional configuration information additionally used according to at least one handover type among the plurality of handover types, and transmit the common handover configuration information and the additional configuration information to the user equipment.

[0014] The disclosed embodiment provides a device and method capable of effectively providing a service in a mobile communication system.

[0015] FIG. 1 is a diagram illustrating the structure of an LTE system according to one embodiment of the present disclosure.

[0016] FIG. 2 is a diagram illustrating a wireless protocol structure of an LTE system according to one embodiment of the present disclosure.

[0017] FIG. 3 is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0018] FIG. 4 is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0019] FIG. 5 is a block diagram illustrating the structure of a terminal according to an embodiment of the present disclosure.

[0020] FIG. 6 is a block diagram showing the configuration of an NR base station according to an embodiment of the present disclosure.

[0021] FIG. 6A illustrates a schematic diagram supporting mobility of a terminal through common target cell configuration in a wireless communication system according to various embodiments of the present disclosure.

[0022] FIG. 6b illustrates a signal structure when a single reference setting is used for target cell setting for a terminal according to one embodiment of the present disclosure.

[0023] FIG. 6c illustrates a signal structure when multiple reference settings are used for target cell setting for a terminal according to one embodiment of the present disclosure.

[0024] FIG. 6d illustrates a flowchart of a network providing a reference setting and a delta setting to a terminal according to one embodiment of the present disclosure.

[0025] FIG. 7 is a diagram for explaining common target cell setting information that a network transmits to a terminal when the target cell setting is the same regardless of the movement method of the terminal according to one embodiment of the present disclosure.

[0026] FIG. 8 is a diagram for explaining common target cell setting information that a network transmits to a terminal when the target cell setting is different depending on the movement method of the terminal according to one embodiment of the present disclosure.

[0027] FIG. 9 is a diagram for explaining a case where information indicating a movement method of a terminal supported by a target cell is included in common target cell setting information according to one embodiment of the present disclosure.

[0028] FIG. 10 is a diagram for explaining a case in which common cell settings are set to a terminal according to one embodiment of the present disclosure.

[0029] FIG. 11 is a diagram for explaining a case in which LTM is performed based on common cell settings according to one embodiment of the present disclosure.

[0030] FIG. 12 is a diagram for explaining a case where a terminal performs a general handover based on a common cell setting according to one embodiment of the present disclosure.

[0031] FIG. 13 is a diagram for explaining a case where a terminal performs conditional handover based on common cell settings according to one embodiment of the present disclosure.

[0032] FIG. 14 is a diagram for explaining a case in which a common cell setting is updated when a source cell setting is changed according to one embodiment of the present disclosure.

[0033] FIG. 15 is a diagram for explaining a case in which a terminal is instructed to remove target cell configuration information when resource allocation for mobility is not possible in a target node according to one embodiment of the present disclosure.

[0034] The operating principles of the present disclosure are described in detail below with reference to the attached drawings. In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents of this specification.

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

[0036] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although the LTE or LTE-A system may be described below as an example, the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in a system to which the embodiments of the present disclosure may be applied, and 5G below may also be a concept that includes existing LTE, LTE-A, and other similar services. Furthermore, the present disclosure may be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present disclosure. It will be appreciated that each block of the processing flow diagrams and combinations of the flow diagrams can be executed by computer program instructions.

[0037] These computer program instructions may be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, so that the instructions executed by the processor of the computer or other programmable data processing apparatus create means for performing the functions described in the flowchart block(s). These computer program instructions may also be stored in a computer-available or computer-readable memory that can be directed to a computer or other programmable data processing apparatus to implement functions in a particular manner, so that the instructions stored in the computer-available or computer-readable memory can produce an article of manufacture that includes instruction means for performing the functions described in the flowchart block(s). The computer program instructions may also be installed on a computer or other programmable data processing apparatus, so that a series of operational steps are performed on the computer or other programmable data processing apparatus to create a computer-implemented process, so that the instructions executing on the computer or other programmable data processing apparatus can provide steps for performing the functions described in the flowchart block(s).

[0038] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order depending on the corresponding function. In this case, the term '~unit' used in the present embodiment means software or a hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the '~unit' may perform 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 execute one or more processors. Thus, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality 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'. In addition, the components and '~ units' may be implemented to reproduce one or more CPUs within a device or a secure multimedia card. Also, in an embodiment, the '~ unit' may include one or more processors.

[0039] For convenience of explanation, this disclosure uses terms and names defined in the 5GS and NR standards, which are standards defined by the 3rd Generation Partnership Project (3GPP) among the existing communication standards. However, this disclosure is not limited to the above terms and names and can be equally applied to wireless communication networks that follow other standards. For example, this disclosure can be applied to the 3GPP 5GS / NR (5th generation mobile communication standard).

[0040] The present disclosure relates to a technology for ensuring mobility of a terminal through common settings in a wireless communication system.

[0041] According to one embodiment of the present disclosure, a base station may prepare multiple mobility functions for a terminal to provide mobility of the terminal. If configuration of multiple mobility functions is required for the same target cell, the terminal may maintain target cell configuration for each function for the same target cell, and the base station may transmit a signal for target cell configuration for each function to the terminal. Therefore, memory resources of the terminal and wireless resources of the terminal and base station may be unnecessarily wasted for configuration of the same target cell.

[0042] According to one embodiment of the present disclosure, a terminal can perform various types of mobility functions while using minimal terminal computing resources and wireless resources.

[0043] FIG. 1 is a diagram illustrating the structure of an LTE system according to one embodiment of the present disclosure.

[0044] Referring to FIG. 1, as illustrated, a wireless access network of an LTE system may be composed of next-generation base stations (Evolved Node Bs, hereinafter referred to as ENBs, Node Bs or base stations) (1-05, 1-10, 1-15, 1-20), a mobility management entity (MME) (1-25) and an S-GW (1-30, Serving-Gateway). A user equipment (UE or terminal) (1-35) may access an external network through the ENBs (1-05 to 1-20) and the S-GW (1-30).

[0045] In Fig. 1, ENBs (1-05 to 1-20) may correspond to existing Node Bs of a UMTS (universal mobile telecommunication system) system. ENBs are connected to UEs (1-35) via a wireless channel and may perform more complex roles than existing Node Bs. In an LTE system, all user traffic, including real-time services such as VoIP (Voice over IP) via the Internet Protocol, can be serviced through a shared channel. Therefore, a device that collects status information such as the buffer status, available transmission power status, and channel status of UEs and performs scheduling is required, and ENBs (1-05 to 1-20) may be responsible for this. One ENB can typically control multiple cells. For example, in order to implement a transmission rate of 100 Mbps, an LTE system may use Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology in a 20 MHz bandwidth; however, the wireless access technology used by the LTE system to implement the transmission rate is not limited thereto. In addition, ENB (1-05 to 1-20) can apply Adaptive Modulation & Coding (AMC) method that determines modulation scheme and channel coding rate according to the channel condition of the terminal. S-GW (1-30) is a device that provides data bearer and can create or remove data bearer according to the control of MME (1-25). MME is a device that is in charge of mobility management function for terminal as well as various control functions and can be connected to multiple base stations.

[0046] FIG. 2 is a diagram illustrating a wireless protocol structure of an LTE system according to one embodiment of the present disclosure.

[0047] Referring to FIG. 2, the wireless protocol of the LTE system may be composed of Packet Data Convergence Protocol (PDCP) (2-05, 2-40), Radio Link Control (RLC) (2-10, 2-35), Medium Access Control (MAC) (2-15, 2-30), and Physical (PHY) (2-20, 2-25) layers in the terminal and the ENB, respectively; however, the configuration of the wireless protocol of the LTE system is not limited as illustrated in FIG. 2. For example, the configuration of the wireless protocol of the LTE system may include more or fewer layers than the configuration illustrated in FIG. 2.

[0048] According to one embodiment of the present disclosure, PDCP (2-05, 2-40) may be responsible for operations such as IP header compression / decompression. The main functions of PDCP (2-05, 2-40) can be summarized as follows, but the functions of PDCP (2-05, 2-40) are not limited to the examples below.

[0049] - Header compression and decompression (ROHC (robust header compression) only)

[0050] - User data transfer function

[0051] - In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM (acknowledge mode)

[0052] - Order reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

[0053] - Duplicate detection function (Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM)

[0054] - Retransmission function (Retransmission of PDCP SDUs at handover and, for split bearers in DC, of ​​PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

[0055] - Encryption and decryption functions (Ciphering and deciphering)

[0056] - Timer-based SDU (service data unit) discard function (Timer-based SDU discard in uplink.)

[0057] According to one embodiment of the present disclosure, Radio Link Control (RLC) (2-10, 2-35) can perform ARQ operation, etc. by reconfiguring PDCP Packet Data Unit (PDU) to an appropriate size. The main functions of RLC (2-10, 2-35) can be summarized as follows, but the functions of RLC (2-10, 2-35) are not limited to the following examples.

[0058] - Data transfer function (Transfer of upper layer PDUs)

[0059] - ARQ function (Error Correction through ARQ (only for AM data transfer))

[0060] - Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer)

[0061] - Re-segmentation of RLC data PDUs (only for AM data transfer)

[0062] - Reordering of RLC data PDUs (only for UM and AM data transfer)

[0063] - Duplicate detection (only for UM and AM data transfer)

[0064] - Error detection function (Protocol error detection (only for AM data transfer))

[0065] - RLC SDU discard function (RLC SDU discard (only for UM and AM data transfer))

[0066] - RLC re-establishment function

[0067] According to one embodiment of the present disclosure, the MAC (2-15, 2-30) is connected to multiple RLC layer devices configured in one terminal, and can perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of the MAC (2-15, 2-30) can be summarized as follows, but the functions of the MAC (2-15, 2-30) are not limited to the examples below.

[0068] - Mapping function (Mapping between logical channels and transport channels)

[0069] - Multiplexing and demultiplexing function (Multiplexing / demultiplexing of MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels)

[0070] - Scheduling information reporting function

[0071] - HARQ function (Error correction through HARQ)

[0072] - Priority handling between logical channels of one UE

[0073] - Priority handling between UEs by means of dynamic scheduling

[0074] - MBMS service identification function

[0075] - Transport format selection function

[0076] - Padding function

[0077] A physical layer (PHY) (2-20, 2-25) according to one embodiment of the present disclosure can perform an operation of 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.

[0078] FIG. 3 is a diagram illustrating the structure of a next-generation mobile communication system according to one embodiment of the present disclosure.

[0079] Referring to FIG. 3, a wireless access network of a next-generation mobile communication system (hereinafter referred to as NR or 5g) may be composed of a next-generation base station (New Radio Node B, hereinafter referred to as NR gNB or NR base station) (3-10) and a next-generation radio core network (New Radio Core Network, NR CN) (3-05). A next-generation radio user equipment (New Radio User Equipment, NR UE or terminal) (3-15) may access an external network through the NR gNB (3-10) and the NR CN (3-05).

[0080] In Fig. 3, the NR gNB (3-10) may correspond to an eNB (Evolved Node B) of an existing LTE system. The NR gNB is connected to an NR UE (3-15) via a wireless channel and may provide a service superior to that of an existing Node B. In the next-generation mobile communication system, all user traffic may be serviced through a shared channel. Therefore, a device that collects status information such as buffer status, available transmission power status, and channel status of UEs and performs scheduling is required, and the scheduling may be performed by the NR NB (3-10). One NR gNB may control multiple cells.

[0081] According to one embodiment of the present disclosure, in order to achieve ultra-high-speed data transmission compared to conventional LTE, a bandwidth exceeding the typical maximum bandwidth may be applied in a next-generation mobile communication system. Furthermore, beamforming technology may be additionally incorporated into Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology.

[0082] In addition, according to one embodiment of the present disclosure, an adaptive modulation and coding (AMC) method that determines a modulation scheme and a channel coding rate according to the channel condition of the terminal may be applied. NR CN (3-05) may perform functions such as mobility support, bearer setup, and QoS (quality of service) setup. NR CN is a device that is responsible for various control functions as well as mobility management functions for the terminal and may be connected to multiple base stations.

[0083] Additionally, according to one embodiment of the present disclosure, the next-generation mobile communication system can also be interoperable with an LTE system, and the NR CN can be connected to an MME (3-25) through a network interface. The MME can be connected to an eNB (3-30), which is an LTE base station.

[0084] FIG. 4 is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system according to one embodiment of the present disclosure.

[0085] Referring to FIG. 4, the wireless protocol of the next-generation mobile communication system may include NR Service Data Adaptation Protocol (SDAP) (4-01, 4-45), NR PDCP (4-05, 4-40), NR RLC (4-10, 4-35), NR MAC (4-15, 4-30), and NR PHY (4-20, 4-25) layers in the terminal and NR base station, respectively. Of course, the wireless protocol of the next-generation mobile communication system may include more or fewer layers than the configuration illustrated in FIG. 4.

[0086] Hereinafter, in the present disclosure, the term 'layer device' refers to a layer of NR and may be used interchangeably with 'layer'.

[0087] According to one embodiment of the present disclosure, the main functions of the SDAP layer device (4-01, 4-45) of NR may include some of the following functions, but the functions of the SDAP layer device (4-01, 4-45) of NR are not limited to the following examples.

[0088] Transfer of user plane data

[0089] Mapping between a QoS flow and a DRB for both DL and UL

[0090] QoS flow ID marking function for both uplink and downlink (marking QoS flow ID in both DL and UL packets)

[0091] Ability to map relective QoS flow to data bearer for the UL SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0092] For SDAP layer devices (4-01, 4-45), the terminal can be configured by a Radio Resource Control (RRC) message for each PDCP layer device, per bearer, or per logical channel, whether to use the header of the SDAP layer device or whether to use the function of the SDAP layer device (4-01, 4-45). When the SDAP header is configured, the terminal can instruct the terminal to update or reset the mapping information for the QoS flow and data bearer of the uplink and downlink by a 1-bit indicator for reflecting the Non-Access Stratum (NAS) Quality of Service (QoS) of the SDAP header (NAS reflective QoS) and a 1-bit indicator for reflecting the Access Stratum (AS) QoS of the SDAP header. According to one embodiment, the SDAP header can include QoS flow ID information indicating the QoS. According to one embodiment, QoS information may be used as data processing priority, scheduling information, etc. to support smooth service.

[0093] According to one embodiment of the present disclosure, the main functions of the NR PDCP layer device (4-05, 4-40) may include some of the following functions, but the functions of the NR PDCP layer device (4-05, 4-40) are not limited to the following examples.

[0094] - Header compression and decompression (ROHC only)

[0095] - User data transfer function

[0096] - In-sequence delivery of upper layer PDUs

[0097] - Out-of-sequence delivery of upper layer PDUs

[0098] - PDCP PDU reordering for reception

[0099] - Duplicate detection of lower layer SDUs

[0100] - Retransmission function (Retransmission of PDCP SDUs)

[0101] - Encryption and decryption functions (Ciphering and deciphering)

[0102] - Timer-based SDU discard in uplink.

[0103] In the above, the reordering function of the NR PDCP layer device (4-05, 4-40) may mean a function of reordering PDCP PDUs received from a lower layer in order based on a PDCP SN (sequence number). The reordering function of the NR PDCP layer device (4-05, 4-40) may include a function of transmitting data to an upper layer in the reordered order, or may include at least one of a function of directly transmitting data without considering the order, a function of recording lost PDCP PDUs by reordering the order, a function of reporting a status of lost PDCP PDUs to the transmitting side, or a function of requesting retransmission of lost PDCP PDUs.

[0104] The main functions of the NR RLC layer device (4-10, 4-35) according to one embodiment of the present disclosure may include some of the following functions, but the functions of the NR RLC layer device (4-10, 4-35) are not limited to the following examples.

[0105] - Data transfer function (Transfer of upper layer PDUs)

[0106] - In-sequence delivery of upper layer PDUs

[0107] - Out-of-sequence delivery of upper layer PDUs

[0108] - ARQ function (Error Correction through ARQ)

[0109] - Concatenation, segmentation and reassembly of RLC SDUs

[0110] - Re-segmentation of RLC data PDUs

[0111] - Reordering of RLC data PDUs

[0112] - Duplicate detection function

[0113] - Protocol error detection

[0114] - RLC SDU discard function

[0115] - RLC re-establishment function

[0116] In the above, the in-sequence delivery function of the NR RLC layer device (4-10, 4-35) may mean the function of sequentially delivering RLC SDUs received from a lower layer to an upper layer. The in-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include the function of reassembling and delivering multiple RLC SDUs received in segments when one RLC SDU is originally divided into multiple RLC SDUs and delivered to an upper layer.

[0117] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include at least one of a function of reordering received RLC PDUs based on an RLC SN (sequence number) or a PDCP SN (sequence number), a function of reordering the sequence and recording lost RLC PDUs, a function of reporting a status of lost RLC PDUs to the transmitting side, or a function of requesting retransmission of lost RLC PDUs.

[0118] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include a function of sequentially delivering only the RLC SDUs up to the lost RLC SDU to the upper layer when there is a lost RLC SDU.

[0119] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include a function of sequentially delivering to the upper layer all RLC SDUs received before a predetermined timer starts if a predetermined timer has expired even if there are lost RLC SDUs.

[0120] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include a function of sequentially delivering all RLC SDUs received up to the present time to the upper layer if a predetermined timer has expired even if there are lost RLC SDUs.

[0121] According to one embodiment of the present disclosure, an NR RLC layer device (4-10, 4-35) can process RLC PDUs in the order in which they are received and deliver them to an NR PDCP layer device (4-04, 4-40) regardless of the order of the sequence number (Out-of sequence delivery).

[0122] According to one embodiment of the present disclosure, when an NR RLC layer device (4-10, 4-35) receives a segment, it can receive segments stored in a buffer or to be received later, reconstruct them into a complete RLC PDU, and then transmit them to an NR PDCP layer device (4-04, 4-40).

[0123] According to one embodiment of the present disclosure, the NR RLC layer device (4-10, 4-35) may not include a concatenation function, and may perform the function in the NR MAC layer device (4-15, 4-30) or may be replaced by a multiplexing function of the NR MAC layer device (4-15, 4-30).

[0124] In the above, the out-of-sequence delivery function of the NR RLC layer device (4-10, 4-35) may mean a function of directly delivering RLC SDUs received from a lower layer to an upper layer regardless of the order.

[0125] According to one embodiment of the present disclosure, the out-of-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include a function of reassembling multiple RLC SDUs received in segmentation when one RLC SDU is originally received in segmentation of multiple RLC SDUs and delivering the reassembled multiple RLC SDUs to an upper layer.

[0126] According to one embodiment of the present disclosure, the out-of-sequence delivery function of the NR RLC layer device (4-10, 4-35) may include a function of storing and arranging the RLC SN or PDCP SN of received RLC PDUs to record lost RLC PDUs.

[0127] According to one embodiment of the present disclosure, the NR MAC layer device (4-15, 4-30) may be connected to multiple NR RLC layer devices configured in one terminal (e.g., the NR RLC layer devices (4-10, 4-35) of FIG. 4), and the main functions of the NR MAC layer device (4-15, 5-30) may include some of the following functions, but the functions of the NR MAC layer device (4-15, 5-30) are not limited to the following examples.

[0128] - Mapping function (Mapping between logical channels and transport channels)

[0129] - Multiplexing / demultiplexing of MAC SDUs

[0130] - Scheduling information reporting function

[0131] - HARQ function (Error correction through HARQ)

[0132] - Priority handling between logical channels of one UE

[0133] - Priority handling between UEs by means of dynamic scheduling

[0134] - MBMS service identification function

[0135] - Transport format selection function

[0136] - Padding function

[0137] According to one embodiment of the present disclosure, an NR PHY layer device (4-20, 4-25) can perform an operation of channel coding and modulating data transmitted from an upper layer, converting it into an OFDM symbol, and transmitting it through a wireless channel, or demodulating and channel decoding an OFDM symbol received through a wireless channel and transmitting it to an upper layer.

[0138] FIG. 5 is a block diagram illustrating the structure of a terminal according to an embodiment of the present disclosure.

[0139] Referring to FIG. 5, a terminal according to one embodiment of the present disclosure may include an RF (Radio Frequency) processing unit (5-10), a baseband processing unit (5-20), a storage unit (5-30), and a control unit (5-40).

[0140] The RF processing unit (5-10) according to one embodiment of the present disclosure can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. The RF processing unit (5-10) can up-convert a baseband signal provided from the baseband processing unit (5-20) into an RF band signal and transmit the same through an antenna, and down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (5-10) can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In Fig. 5, only one antenna is illustrated, but the terminal can be equipped with multiple antennas. In addition, the RF processing unit (5-10) can include multiple RF chains. Furthermore, the RF processing unit (5-10) can perform beamforming. For the above beamforming, the RF processing unit (5-10) can adjust the phase and magnitude of each signal transmitted and received through multiple antennas or multiple antenna elements. In addition, the RF processing unit (5-10) can perform MIMO. When the RF processing unit (5-10) performs the MIMO operation, it can receive multiple layers. The RF processing unit (5-10) can perform reception beam sweeping by appropriately setting multiple antennas or antenna elements according to the control of the control unit, or can adjust the direction and beam width of the reception beam so that the reception beam is coordinated with the transmission beam.

[0141] According to one embodiment of the present disclosure, the baseband processing unit (5-20) can perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, the baseband processing unit (5-20) can generate complex symbols by encoding and modulating a transmission bit stream when transmitting data. In addition, the baseband processing unit (5-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (5-10) when receiving data. For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, the baseband processing unit (5-20) can generate complex symbols by encoding and modulating a transmission bit stream when transmitting data, map the complex symbols to subcarriers, and then configure 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 (5-20) divides the baseband signal provided from the RF processing unit (5-10) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform), and then restores the received bit string through demodulation and decoding.

[0142] According to one embodiment of the present disclosure, the baseband processing unit (5-20) and the RF processing unit (5-10) can transmit and receive signals as described above. Accordingly, in the present disclosure, the baseband processing unit (5-20) and the RF processing unit (5-10) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (5-20) and the RF processing unit (5-10) 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 (5-20) and the RF processing unit (5-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. Additionally, different frequency bands may include super high frequency (SHF) (e.g., 2.NRHz, NRhz) bands, millimeter wave (mm wave) (e.g., 60GHz) bands.

[0143] According to one embodiment of the present disclosure, the storage unit (5-30) can store data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (5-30) can store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit (5-30) can provide the stored data upon request from the control unit (5-40).

[0144] According to one embodiment of the present disclosure, the control unit (5-40) can control the overall operations of the terminal. For example, the control unit (5-40) can transmit and receive signals through the baseband processing unit (5-20) and the RF processing unit (5-10). In addition, the control unit (5-40) can record data in the storage unit (5-40) and read data recorded in the storage unit (5-40). According to one embodiment of the present disclosure, the control unit (5-40) can include at least one processor. For example, the control unit (5-40) can include a communication processor (CP) that performs control for communication and an application processor (AP) that controls an upper layer (e.g., an application program).

[0145] Figure 6 is a block diagram showing the configuration of an NR base station according to one embodiment of the present invention.

[0146] As illustrated in FIG. 6, according to one embodiment of the present disclosure, the base station may include an RF processing unit (6-10), a baseband processing unit (6-20), a backhaul communication unit (6-30), a storage unit (6-40), and a control unit (6-50), but the configuration of the NR base station is not limited to the configuration illustrated in FIG. 6. For example, the NR base station may include fewer or more configurations than the configuration illustrated in FIG. 6.

[0147] According to one embodiment of the present disclosure, the RF processing unit (6-10) can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. The RF processing unit (6-10) can up-convert a baseband signal provided from the baseband processing unit (6-20) into an RF band signal and transmit the up-converted signal to a terminal via an antenna, and down-convert an RF band signal received from the terminal via the antenna into a baseband signal. For example, the RF processing unit (6-10) can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In FIG. 6, only one antenna is illustrated, the RF processing unit (6-10) can be equipped with multiple antennas. In addition, the RF processing unit (6-10) can include multiple RF chains. According to one embodiment of the present disclosure, the RF processing unit (6-10) can perform beamforming. For beamforming, the RF processing unit (6-10) can adjust the phase and amplitude 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.

[0148] According to one embodiment of the present disclosure, the baseband processing unit (6-20) can perform a conversion function between a baseband signal and a bit stream according to the physical layer specification of the first wireless access technology. For example, when transmitting data, the baseband processing unit (6-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (6-20) can restore the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (6-10). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (6-20) can generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols through an IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (6-20) can divide the baseband signal provided from the RF processing unit (6-10) into OFDM symbol units, restore the signals mapped to subcarriers through FFT operation, and then restore the received bit string through demodulation and decoding. The baseband processing unit (6-20) and the RF processing unit (6-10) can transmit and receive signals as described above. Accordingly, in the present disclosure, the baseband processing unit (6-20) and the RF processing unit (6-10) may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0149] According to one embodiment of the present disclosure, the backhaul communication unit (6-30) may provide an interface for performing communication with other nodes within the network. For example, the backhaul communication unit (6-30) may convert a bit string transmitted from the main base station to another node (e.g., an auxiliary base station, a core network) into a physical signal, and may convert a physical signal received from another node (e.g., an auxiliary base station, a core network) into a bit string.

[0150] According to one embodiment of the present disclosure, the storage unit (6-40) can store data such as basic programs, application programs, and configuration information for the operation of the main base station. The storage unit (6-40) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (6-40) can store information that serves as a basis for determining whether to provide or terminate multiple connections to a terminal. In addition, the storage unit (6-40) can provide the stored data upon request from the control unit (6-50).

[0151] According to one embodiment of the present disclosure, the control unit (6-50) can control the overall operations of the base station. For example, the control unit (6-50) can transmit and receive signals through the baseband processing unit (6-20) and the RF processing unit (6-10) or through the backhaul communication unit (6-30). In addition, the control unit (6-50) can record data in the storage unit (6-40) and read data stored in the storage unit (6-40). For this purpose, the control unit (6-50) can include at least one processor.

[0152] According to one embodiment of the present disclosure, at least one component of a base station may be implemented on a single chip. Furthermore, each component of the base station may be operable to perform embodiments of the present disclosure.

[0153] NR introduces various mobility features such as general handover, conditional handover (CHO), conditional pscell change / addition (CPAC), L1 / L2-triggered mobility (LTM), and dual active protocol stack mobility (DAPS). The core of mobility operations is to perform handover by having the terminal apply the settings in the target cell, and for each mobility method, the conditions / timing / method for applying the settings in the target cell may be different.

[0154] According to one embodiment of the present disclosure, the purpose of mobility methods may be handover. Therefore, rather than having target cell settings for each mobility method, it is more likely that the same cell settings will be present regardless of the mobility method. For example, the target cell settings for a single target cell may include the same cell settings regardless of the mobility method. In particular, in the case of CHO or LTM, the target cell settings are transmitted to the terminal in advance through presetting, allowing the terminal to store and manage the target cell settings. However, the circumstances and methods for transmitting the signal to perform a handover may differ.

[0155] According to one embodiment of the present disclosure, in NR, even when the target cell configuration for a general handover, LTM, or CHO is the same, the pre-configuration procedures for the target cell for the handover can all be independent. Accordingly, the target cell configuration for LTM is stored in the terminal for LTM, the target cell configuration for CHO is stored separately in the terminal for CHO, and the target configuration for the general handover can also be provided to the terminal as an RRCReconfiguration including the same configuration. This may cause the terminal to store the same target cell configuration in memory in the form of multiple copies, which may unnecessarily waste the memory of the terminal. Furthermore, the process of the base station repeatedly transmitting the same target cell configuration to the terminal may result in a waste of radio resources. Furthermore, the process of preparing the target cell configuration for the handover may require inter-node signals between the target node and the source node depending on the method. This may result in the use of unnecessary inter-node signals at the network level. Additionally, after the base station transmits the target cell settings to the terminal, in various situations, when the target cell settings transmitted to the terminal are to be updated or deleted, separate inter-node signals for each mobility method, duplicated signals in the wireless section between the base station and the terminal, and target cell settings may be transmitted.

[0156] According to one embodiment of the present disclosure, as in NR, a terminal can perform a handover by applying configuration information from a target cell. Configuration information from the target cell may be generated at the RRC protocol layer, as in NR, but is not limited thereto. For example, configuration information from the target cell may be processed in a newly developed control plane protocol for 6G.

[0157] Hereinafter, in the present disclosure, regardless of which protocol stack is considered, if a network transmits a message to a terminal and the terminal applies the received message, thereby changing the serving cell, the message will be referred to as a 'handover command'. According to one embodiment of the present disclosure, the handover command may include at least one of physical layer configuration information and L2 configuration information (MAC layer configuration information in NR), RLC logical channel configuration information, radio bearer configuration information, measurement configuration information, and security-related configuration information to be applied in the target cell. In particular, the handover command may include physical layer information in the target cell (for example, information for recognizing the target cell, included in the reconfigurationWithsync field included in the RRCReconfiguration message in NR, such as a physical cell ID (PCI) and frequency information of the cell, C-RNTI information, other cell-specific common configuration information of the corresponding target cell, and terminal-specific configuration information).

[0158] In the present disclosure, when a network sets a mobile target cell setting for a specific target cell in advance to a terminal, a method for instructing the terminal to use the target cell setting for all or part of the mobility methods that perform handover to the target may be provided, and a method for managing the target cell setting may be provided.

[0159] According to one embodiment of the present disclosure, the target cell setting for one target cell may include the same target cell setting regardless of the movement method.

[0160] According to one embodiment of the present disclosure, when a terminal performs a handover to a single target cell, the terminal may perform the handover using the target cell configuration according to the instructions of the base station. For example, the network may store and manage a single target cell configuration for a specific target cell, and transmit a unique ID associated with the target cell configuration to the terminal. In this case, since a single identical target cell configuration is used for a multi-mobility scheme, the identical target cell configuration may be referred to as a common target cell configuration. The common target cell configuration may include a unique target cell configuration for a single target cell. In addition, the common target cell configuration may correspond to an RRCReconfiguration message including a handover (HO) execution indicator, such as reconfigurationWithSync in NR, or a handover command including various settings and target cell identification information required for the target cell in 6G.

[0161] According to one embodiment of the present disclosure, a terminal can store a unique target cell configuration for a single target cell by linking it to an ID. In this case, a terminal variable can be used.

[0162] According to one embodiment of the present disclosure, when a network instructs a terminal to move to a specific target cell using a specific movement method, the network may indicate a specific target cell associated with the terminal via an ID. Various methods may be used to indicate each method.

[0163] According to one embodiment of the present disclosure, when a network wishes to change or delete a unique target cell configuration for a specific target cell, it may indicate the target cell configuration to be changed or deleted through an ID associated with the specific target cell, and then issue a command to change or delete the configuration. The terminal may identify the target cell configuration to be changed or deleted based on the ID, and perform an operation to change or delete the target cell configuration.

[0164] According to one embodiment of the present disclosure, a method for a network to transmit a common target cell configuration to a terminal may be divided into opt 1. when the target cell configuration is the same regardless of the movement method, opt 2. when the target cell configuration has different parts depending on the movement method, and opt 3. when, in the cases of opt 1 and 2, a movement method supported by each target cell is additionally required.

[0165] FIG. 6A illustrates a schematic diagram supporting mobility of a terminal through common target cell configuration in a wireless communication system according to various embodiments of the present disclosure.

[0166] According to the existing method for supporting handover according to the movement of a terminal, the network can provide the target cell configuration to the terminal using a separate inter-node signal for each mobility configuration corresponding to each mobility mode of the terminal. The network can transmit overlapping inter-node signals for each mobility mode to deliver the same configuration for the same target cell to the terminal. For example, the target cell can transmit the overlapping Cell A configuration to the serving cell. Additionally, the network can transmit the same target cell configuration to the terminal through a different container. The terminal can store the overlapping target cell configuration received from the base station in its memory. Finally, separately from the target cell configuration stored in the terminal's memory, a handover preparation (HO preparation inter-node) signal is exchanged between the source base station and the target base station to instruct the terminal to perform an immediate L3 handover for the same target cell, and the source base station can transmit a handover command to the terminal. Due to this, if the existing method is followed, unnecessary consumption of wireless resources and unnecessary waste of terminal power and memory may occur.

[0167] On the other hand, according to various embodiments of the present disclosure, the network can transmit only one configuration to the terminal to support the mobility of the terminal toward one target cell. For example, the target cell (Target cell A in FIG. 6A) can transmit unified handover configuration information (unified HO config) to the serving cell. In addition, the network can instruct the terminal on the required mobility method of the terminal according to the needs of the network. For example, the network can instruct the terminal on any one of CHO, LTM, or L3HO mobility methods through a unified handover command (unified HO CMD).

[0168] FIG. 6b illustrates a signal structure when a single reference configuration is used for target cell configuration for a terminal according to one embodiment of the present disclosure. The signal structure of FIG. 6b can be understood as a signal structure that can be used when using a reference configuration and a delta configuration in the case of the above-described OPT 1.

[0169] According to one embodiment of the present disclosure, in addition to the case where there is one target cell configuration (common target cell configuration) for each target cell, in the case where information of different target cell configurations is substantially the same, the network or the terminal may maintain one or multiple reference target cell configurations for multiple target cells and perform movement through the reference target cell configurations. In this case, when the network transmits target cell configuration information to the terminal, the reference target cell configuration may be applied to opts 1, 2, and 3. In this case, in each opt, instead of an RRCReconfiguration message corresponding to each ID in the candidate cell list, a delta configuration of a cell corresponding to each ID may be transmitted to the terminal. When the delta configuration information of the cell corresponding to each ID is transmitted to the terminal, when the terminal moves to a specific target cell by the above-described movement performing and instructing methods, the terminal may be required to first derive the target cell configuration in order to apply the configuration of the target cell, and then apply the derived target cell configuration. At this time, in order for the terminal to derive the target cell configuration for a specific target cell, the delta configuration corresponding to the target cell ID may be combined with the reference configuration. Here, the operation of combining the delta configuration with the reference configuration may mean an operation of considering (acknowledging) the reference configuration as the current terminal configuration (in this case, all configuration information transmitted by RRC messages configured in the existing terminal may be removed, and the configuration on the reference may be applied), and applying the delta configuration on top of the reference configuration.The action of applying the delta setting may include, if an IE (information element) of a terminal to which the reference setting is applied exists in the delta setting and is identical to an IE in the current reference setting, overwriting the value of the existing reference setting with the value of the delta setting for that IE; if an IE that is not in the reference setting exists in the delta setting, newly setting the value of the IE in the delta setting to the terminal; and, if a release is indicated in the delta setting for an IE that exists in the reference setting, deleting the IE that has been indicated for release without a separate setting.

[0170] FIG. 6c illustrates a signal structure when multiple reference settings are used for target cell configuration for a terminal according to one embodiment of the present disclosure. The signal structure illustrated in FIG. 6c can be understood as a signal structure that can be used when multiple reference settings are configured for a terminal in the case of the aforementioned OPT 2.

[0171] According to one embodiment, a network can instruct a terminal to have multiple reference configurations. When the network instructs a terminal to have multiple reference configurations, the network can introduce a separate ID that distinguishes each reference configuration as a common configuration and transmit it to the terminal. In addition to the delta configuration transmitted for each candidate cell ID, the network can transmit to the terminal the ID of the reference configuration used to derive the target cell configuration of the cell of the corresponding ID by adding it to the configuration information of the candidate cell list. For example, the network can transmit to the terminal an indicator (ref 1) indicating the first reference configuration (reference configuration 1) or an indicator (ref 2) indicating the second reference configuration (reference configuration 2) by adding it to the configuration information of the candidate cell list. In the case of using multiple reference settings, when a terminal is to move to a specific candidate cell and derives the target cell setting of the candidate cell, the final target cell setting can be derived by applying the delta setting indicated in association with the candidate cell ID based on the reference setting indicated in association with the ID of the candidate cell.

[0172] According to one embodiment, the reference configuration and the delta configuration may be transmitted as separate mobility-type-specific configuration information from the candidate cell list. For example, in the case of opt 1, 2, and 3, the network may transmit to the terminal at least one reference configuration required for deriving the configuration of the candidate cell as mobility-type-independent information, and a candidate cell list. Here, the candidate cell list may include each candidate cell ID and a reference configuration ID (if there are multiple reference configurations) associated with the candidate cell corresponding to each candidate cell ID. In addition, each transmission-type-specific configuration transmitted to the terminal may include, for each candidate cell in the candidate cell list for each mode, the candidate cell ID indicated by the candidate cell list, configuration information for each mode required by the candidate cell (for example, condition information in the case of CHO, LTM-CSI resource information in the case of LTM, etc.), the ID of the reference configuration used to derive target cell configuration information for the candidate cell, and delta configuration information. When a terminal moves to a specific candidate cell in a specific manner, the terminal can derive a final target cell configuration by combining the reference configuration and delta configuration indicated in the candidate cell configuration in the specific manner. By applying the derived final target cell configuration, the terminal can perform movement with the candidate cell as the target cell.

[0173] According to one embodiment, if the reference configuration information indicated to the terminal does not exist, or if the ID of the reference configuration information for deriving target cell configuration information for each candidate cell (if multiple reference configurations are set) is not indicated to the terminal, the terminal can derive the final target cell configuration information by combining the current configuration information and delta configuration information linked to the target cell, rather than the reference configuration.

[0174] According to one embodiment, when deriving target cell configuration information, if there is reference configuration information associated with the target cell but no delta configuration information associated with the target cell, the terminal can derive final target cell configuration information using only the reference configuration information.

[0175] In one embodiment, the reference configuration is generally given regardless of the candidate cell ID, and the delta configuration may be given for each candidate cell ID in the candidate cell list or the candidate configuration for each mobility method. In this case, the network may additionally transmit an indicator to the terminal indicating whether the delta configuration is a configuration added to the reference configuration, a delta configuration added to the terminal's current configuration, or a complete configuration that ignores or erases the terminal's current configuration and overwrites the delta configuration. A terminal that receives such an indicator can, when moving to a specific candidate cell as a target cell, finally derive the target cell configuration based on the indicator.

[0176] According to one embodiment, the terminal may combine the reference configuration information and the delta configuration information when the terminal receives an RRCReconfiguration message including the reference configuration information and the delta configuration information, or when the terminal receives an actual handover instruction from the network. The terminal may perform decoding or a compliance check at the time of combining the reference configuration information and the delta configuration information. If the compliance check of the terminal fails in this order, a radio link failure (RLF) or an RRCReconfiguration failure may occur. The terminal may perform an RRC Reestablishment operation to resolve such failure.

[0177] FIG. 6d illustrates a flowchart of a network providing a reference setting and a delta setting to a terminal according to one embodiment of the present disclosure.

[0178] In one embodiment, a terminal may transmit capability information related to performing mobility operations using common settings to a source node (S-node). For example, a terminal (UE) may receive a UE capability inquiry message from a source node (S-node), and the terminal may transmit a UE capability indication to the source node.

[0179] According to one embodiment, the terminal may transmit, to the source node, measurement results through measurement settings of RRM, or CSI measurement results in L1.

[0180] According to one embodiment, the source node may determine a candidate cell to move to based on information received from the terminal (determine which cell is the target cell), determine which mobility scheme to be used for each cell (determine which mobility scheme to be used), and determine a reference setting for each candidate cell to consider for the terminal.

[0181] According to one embodiment, the source node may transmit to each candidate node, through an HO request message or a corresponding inter-node message, at least one of cell information to be considered as a mobile candidate cell by the candidate node, information on a mobile mode to be considered by the cell for the terminal, configuration information of the current terminal in the source cell, and reference configuration information. For example, referring to FIG. 6d, the source node may transmit, to each of the candidate nodes (C-node 1, C-node 2), an HO request message including req_CHO, req_LTM, req_HO indicators, configuration information in the source cell (srcConfig), and reference configuration information (refConfig). (In addition to the HO Request message, a separate command on the inter-node interface may be used.)

[0182] According to one embodiment, a candidate node that has received information from a source node (S-node) may perform admission control on each candidate cell proposed as a source node and determine whether to allocate resources. In addition, the candidate node may determine whether to create a delta configuration based on a reference cell for target cell configuration for candidate cells determined to be allocated resources, or a full configuration unrelated to the reference configuration. The candidate node may generate a configuration determined among the delta configuration based on the reference cell or the full configuration unrelated to the reference configuration. In addition, the candidate node may generate an indicator indicating whether the generated configuration for the candidate cell is a delta configuration or a full configuration. In addition to the above information, additional configuration information required for each mobility method will be described in the following drawings.

[0183] According to one embodiment, the candidate nodes (C-node 1, C-node 2) may transmit at least one of the following information to the source node (S-node) via an inter-node message. In Fig. 6d, the candidate nodes are illustrated as transmitting an HO Request ACK message to the source node, but the type of message transmitted is not limited thereto, and the candidate nodes may transmit a new (or other) inter-node message corresponding to the HO Request ACK message to the source node.

[0184] - For specific admitted candidate cells,

[0185] -- Information on the mobility methods allowed by the cell (e.g., L3 handover, CHO, LTM, CLTM, etc.)

[0186] -- Setting information for the cell

[0187] --- Additionally, an indicator indicating whether it is a full setting or a delta setting.

[0188] In one embodiment, the source node receiving the information may assign a unique integer ID (candidate cell ID) to each determined candidate cell or to the configuration information of the candidate cell. Furthermore, the source node may transmit configuration information for each movement method and each cell to the terminal by linking it to the corresponding candidate cell ID.

[0189] According to one embodiment, the source node may convey at least one of the following information via an RRCReconfiguration message or a corresponding RRC message:

[0190] - ID for each candidate cell

[0191] - Indicator of the mobility method applicable to the candidate cell for each ID (e.g., information on at least one of L3 handover, conditional handover, LTM, and CLTM)

[0192] - Target cell setting information for each candidate cell for each ID, and delta setting or full setting indicator of the setting information

[0193] According to one embodiment, a terminal that receives information from a source node can store the information in memory (store the candidate cells with its configs).

[0194] In one embodiment, the source node may instruct the terminal to perform a specific type of mobility command. For example, the source node may instruct the terminal to perform any one of L3 handover, conditional handover, LTM, or conditional LTM (CLTM), and a target cell ID. A detailed description of how the source node instructs the terminal to perform a specific type of mobility command will be provided with reference to the drawings below.

[0195] In one embodiment, the terminal can derive final configuration information for the target cell based on information received from the source node. The terminal can then move to the target cell by applying the derived final configuration information.

[0196] In one embodiment, a terminal may perform random access to move to a target cell. Based on the terminal receiving the UL grant, the terminal may transmit an HO complete or RRCReconfigurationComplete message or an equivalent message to the target cell.

[0197] FIG. 7 is a diagram for explaining common target cell setting information that a network transmits to a terminal when the target cell setting is the same regardless of the movement method of the terminal according to one embodiment of the present disclosure.

[0198] The example shown in Fig. 7 may be associated with Opt 1.

[0199] Referring to Fig. 7, in the case of Opt 1, the network transmits each target cell configuration to the terminal through the common cell configuration field or its corresponding field, and at this time, the ID assigned to the corresponding target cell can be signaled together. Additionally, the configurations required for each movement method can be transmitted through fields specific to each movement method. When the terminal is given a common cell configuration, it can be instructed to move to a specific target cell, or when it must move, it can overwrite the configuration of the current cell with the common cell configuration (case 1, applying full configuration or complete configuration), or apply the configuration of the common cell as a delta on the configuration of the current cell and apply it as the final configuration (case 2).

[0200] For example, in the case of CHO, configuration information required when a terminal moves to each target cell is essential. Accordingly, the CHO configuration field (e.g., CHO configuration in FIG. 7) may include condition information linked to the ID given in the common cell field of the target cell configuration for the CHO target cell (e.g., Candidate cell list in FIG. 7) and transmitted to the terminal.

[0201] For example, in the case of LTM, information such as the PCI of the candidate cell, SSB (synchronization signal block) configuration, an indicator indicating whether the configuration for the candidate target cell is complete, configuration information for obtaining early UL (uplink) synchronization, and TCI (transmission configuration indicator) state information for DL ​​(downlink) synchronization are required for each candidate cell. The information can be transmitted to the terminal by linking it with the ID given in the common cell field (e.g., Candidate cell list in FIG. 7) of the target cell configuration for the LTM in the LTM configuration field (e.g., LTM configuration in FIG. 7). Other common information that is not cell-specific information (e.g., reference configuration information, LTM CSI resource configuration information based on the current Pcell) can be given as a common configuration field in the LTM configuration field (e.g., LTM configuration in FIG. 7).

[0202] According to one embodiment of the present disclosure, a terminal can store information present in a common cell configuration field based on given information in a terminal variable or a corresponding variable. Furthermore, the terminal can also store information required for other movement methods in the terminal variable or a corresponding variable. Thereafter, when the network, as needed, directs movement in a specific manner or changes or deletions of a specific target cell configuration, the terminal can perform the desired change or deletion by indicating an ID associated with the target cell in the common cell configuration field.

[0203] FIG. 8 is a diagram for explaining common target cell setting information that a network transmits to a terminal when the target cell setting is different depending on the movement method of the terminal according to one embodiment of the present disclosure.

[0204] The example shown in Fig. 8 may be associated with Opt 2.

[0205] Referring to Fig. 8, in the case of Opt 2, there may be differences in the settings of the target cell depending on each movement method.

[0206] According to one embodiment of the present disclosure, the network transmits each target cell configuration to the terminal via a common cell configuration field or a corresponding field, and may also transmit an ID assigned to the corresponding target cell. Additionally, the network may transmit the configurations required for each mobility method to the terminal via fields specific to each mobility method.

[0207] In the present disclosure, delta configuration information may include configuration information that is to be applied in addition to, preferentially over, or in place of, the current cell configuration (or common cell configuration). Furthermore, applying a delta configuration may include applying the delta configuration information to the current cell configuration (or common cell configuration).

[0208] For example, in the case of CHO, the configuration information required when the terminal moves to each target cell is essential. Accordingly, the CHO configuration field (e.g., CHO configuration in FIG. 8) may include condition information linked to the ID given in the common cell field (e.g., Candidate cell list in FIG. 8) of the target cell configuration for the CHO target cell and may be transmitted to the terminal. In addition, the target cell configuration may have different parts compared to the common cell configuration when performing CHO, and the delta configuration (e.g., delta RRCReconfiguration in FIG. 8) according to the difference may be transmitted to the terminal in association with the ID assigned to the target cell. The final target cell configuration may be one in which the target cell configuration of the common cell is regarded as the current cell configuration of the terminal and the delta configuration is applied thereon (case 1), or one in which the common cell configuration is applied as the delta configuration on top of the current cell configuration and the delta configuration for CHO is additionally applied thereon (case 2). When a terminal needs to perform CHO with a target cell, it can perform CHO by deriving a final target cell setting for CHO and applying the derived final target cell setting.

[0209] For example, in the case of LTM, information such as the PCI and SSB configuration of the candidate cell, an indicator indicating whether the candidate cell configuration is complete or not, configuration information for obtaining early UL synchronization, and TCI state information for DL ​​synchronization are required for each candidate cell. The information can be transmitted to the terminal by linking it with the ID given in the common cell field (e.g., Candidate cell list of FIG. 8) of the target cell configuration for the LTM target cell in the LTM configuration field (e.g., LTM configuration of FIG. 8). In addition, there may be a part that is different from the common cell configuration (e.g., RRCReconfiguration of FIG. 8) when performing LTM. The delta configuration accordingly can be linked with the ID assigned to the target cell and transmitted to the terminal. Accordingly, the final target cell configuration may be one in which the target cell configuration of the common cell is regarded as the current cell configuration of the terminal and the delta configuration (delta config) is applied thereon (case 1), or the common cell configuration is applied as the delta configuration (delta config) on ​​top of the current cell configuration and the delta configuration (delta config) for LTM is additionally applied thereon (case 2). When the terminal needs to perform LTM with the target cell, it can perform LTM by deriving the final target cell configuration for LTM and applying the derived final target cell configuration. Other common information that is not cell-specific information (e.g., reference configuration information, LTM CSI resource configuration information based on the current Pcell) can be given as a common configuration field in the LTM configuration field.

[0210] According to one embodiment of the present disclosure, if there is no delta setting associated with the corresponding target cell in the setting field of each movement method, the terminal can perform HO using only the common cell setting.

[0211] FIG. 9 is a diagram for explaining a case where information indicating a movement method of a terminal supported by a target cell is included in common target cell setting information according to one embodiment of the present disclosure.

[0212] The example shown in Fig. 9 may be associated with Opt 3.

[0213] Referring to FIG. 9, according to one embodiment of the present disclosure, in the case of Opt 3, when the network transmits the common cell configuration to the terminal, it transmits it using the method of opt 1 or opt 2, but additionally, the target cell configuration of each common cell configuration can indicate a movement method (e.g., CHO, LTM, HO of FIG. 9) supported by the corresponding cell configuration. The terminal can store and manage information indicating the movement method in a terminal variable. For example, the target cell configuration corresponding to ID 1 of the common cell configuration field (e.g., Candidate cell list of FIG. 9) can be used for {CHO, LTM, HO}, that is, the CHO method, the LTM method, and the general HO method, as will be described later in the description with respect to FIGS. 11 to 13. The network can cause the terminal to perform movement to the corresponding target cell in the corresponding method by transmitting an indication signal appropriate for each method to the terminal.

[0214] According to one embodiment of the present disclosure, an indication of a movement method supported by a cell configuration can be used for an operation in which the terminal itself clears the configuration of the corresponding method after performing a specific movement method. For example, after successfully performing CHO, the terminal can clear the configurations associated with the CHO method. Here, the configuration associated with CHO can include condition information given in the CHO configuration field and other information, and an indicator indicating that CHO is supported in the configurations of target cells that support CHO among the target cell configurations given in the common cell configuration field. According to one embodiment of the present disclosure, the network can explicitly instruct the terminal to clear the configurations of a specific movement method. In this case, the terminal can clear the configuration of the corresponding method by clearing the support indicator of the specific movement method explicitly indicated by the network in the target cell configurations that indicate support for the corresponding movement method among the common cell configurations.

[0215] For example, in a case where a terminal performs LTM, if the terminal wants to erase the LTM method settings after successfully performing LTM, the terminal can erase the information in the LTM setting field. For example, the terminal can additionally erase the LTM support indicator in target cell settings that have the LTM support indicator in the common cell setting field.

[0216] According to one embodiment of the present disclosure, after performing a corresponding movement for each method, the corresponding settings of the terminal can be erased using an explicit support method indicator, and the terminal can also determine whether the corresponding target cell setting supports a specific movement method through the presence or absence of settings other than the target cell setting existing in a separate setting field for each method. For example, in FIG. 9, since the target cell setting of ID 3 among the common cell settings does not have condition information associated with ID 3 in the CHO setting field, the terminal can determine that the target cell setting of ID 3 does not support CHO. In addition, since the target cell setting of ID 3 includes an LTM setting associated with ID 3 in the LTM setting field, the terminal can determine that the ID 3 target cell setting supports LTM. Accordingly, after performing a specific movement method, the terminal can perform an operation of releasing the settings required to perform the specific movement method.

[0217] According to one embodiment of the present disclosure, in the case of Opt 3, the final target cell configuration to be applied by the terminal may be generated in the same manner as in case 1 and case 2 of the final target cell configuration described above in the description of Opt 1 and Opt 2. In addition, the method by which the terminal applies the generated final target cell configuration may be the same as the method by which the terminal applies the generated final target cell configuration described above in the description of Opt 1 and Opt 2.

[0218] The structure of the setting information and how the terminal performs the movement operation required by the terminal through the transmission of the setting information will be described in detail with reference to FIGS. 10 to 15.

[0219] FIG. 10 is a diagram for explaining a case in which common cell settings are set to a terminal according to one embodiment of the present disclosure.

[0220] According to one embodiment of the present disclosure, a source node (S-node) that operates a terminal and a source cell can obtain information about a mobility method supported by the terminal for mobility operations from the terminal while maintaining a connection state. This process can be performed through a step in which the network requests information about the terminal's capabilities and the terminal provides the network with information about the terminal's capabilities. For example, the above-described operation can be performed through an operation in which the network transmits a UE capability enquiry message to the terminal and the terminal transmits a UE capability indication message to the network. According to one embodiment of the present disclosure, the terminal can provide information about its capabilities on its own. For example, the terminal can provide information about its capabilities to the network by transmitting an RRC message.

[0221] According to one embodiment of the present disclosure, a terminal may receive measurement configuration information operating in L3 or L1 / L2 from a network and perform neighboring cell and beam measurements according to the measurement configuration. The terminal may transmit the neighboring cell and beam measurement results to a serving node. For example, in FIG. 10 , a terminal (UE) may transmit a measurement result (e.g., an L3 MR or any layer meas report of FIG. 10 ) to a serving node (S-node).

[0222] According to one embodiment of the present disclosure, the serving node can determine a target cell and a target node based on the measurement results. Furthermore, according to one embodiment of the present disclosure, the serving node can determine movement to the target cell. At this time, the serving node can determine movement to the target cell using a movement scheme desired by the source node or a movement scheme available to the source node.

[0223] A serving node may send a request message to the target cell of the determined target node, requesting resources for the terminal. The request message may include an Xn message or an inter-node message or an inter-CU message. For example, referring to FIG. 10, the serving node may transmit an Xn message (e.g., HO request (reg_CHO, req_LTM, req_HO indication) of FIG. 10) to the target node. The request message may include a source cell ID, a source node ID, a terminal ID, and an indicator of a movement method desired by the source node. Additionally, in the present disclosure, the source node and the serving node may be the same or different depending on the handover method.

[0224] According to one embodiment of the present disclosure, a target node (T-node) that receives an HO request message may perform an admission control operation to determine whether to allocate resources to a terminal. According to one embodiment of the present disclosure, referring to FIG. 10, the target node (T-node) may generate a target cell configuration based on the indication of whether to allocate resources to a terminal (UE). In addition, at this time, the target node determines an acceptable mobility method, and as a result, transmits target cell configuration information to be given to the terminal to the source node. At this time, the target node may indicate and transmit the mobility methods supported by the target cell configuration. The supported mobility methods may be indicated through information indicating whether or not the source node supports the mobility methods requested by the target node.

[0225] According to one embodiment of the present disclosure, the target cell configuration information may include additional information required in addition to the target cell configuration for each movement method. For example, the additionally required information may include information entered into the above-described CHO configuration field and LTM configuration field. The message transmitted by the target node to the source node may include an Xn, or an inter node or inter-CU message, and may be a response message to a request message transmitted by the source node. For example, referring to FIG. 10, the target node (T-node) may transmit an Xn message (e.g., HO request ACK(usage_CHO, usage_LTM, usage_HO indication, target cell1 configuration, remaining) of FIG. 10) to the source node (S-node).

[0226] According to one embodiment of the present disclosure, a source node receiving a response message assigns a unique ID (the candidate cell ID) to a given target cell configuration.

[0227] According to one embodiment of the present disclosure, a source node may create a setting field for a movement method to which target cell settings are applied, and add setting information required for each movement method (in the case of LTM) to the setting field for the movement method, or add setting information required for each movement method that the source node must write (in the case of CHO, condition information that must be applied when moving from a source cell to the corresponding target cell).

[0228] According to one embodiment of the present disclosure, a source node may provide a common cell configuration (candidate cell config) and configuration information for each mobility scheme (configuration per mob scheme) to a terminal via an RRCReconfiguration message. The terminal may apply the common cell configuration and configuration information for each mobility scheme based on the received RRCReconfiguration message.

[0229] According to one embodiment of the present disclosure, upon receiving an RRCReconfiguration message, the terminal may transmit a complete message to the source node. Furthermore, according to one embodiment of the present disclosure, the terminal may store configuration information for each mobility method in terminal variables.

[0230] According to one embodiment of the present disclosure, the terminal may initiate measurement and evaluation of conditions of CHO when CHO is included in the method supported by the target cell configuration.

[0231] According to one embodiment of the present disclosure, a terminal may perform serving cell and neighboring cell measurements for LTM when LTM is included in a method supported by target cell configuration, and the terminal may perform a reporting operation according to serving cell and neighboring cell measurements for LTM to a source cell.

[0232] FIG. 11 is a diagram for explaining a case in which LTM is performed based on common cell settings for a terminal according to one embodiment of the present disclosure.

[0233] In addition, the example illustrated in FIG. 11 may represent a case in which LTM is performed using the set common cell configuration in a situation in which a common cell configuration is set in a terminal.

[0234] According to one embodiment of the present disclosure, after receiving a common cell configuration, the terminal can measure the beams of the source cell and / or neighboring cells and / or the cells through measurement target information according to the LTM configuration among the received common cell configurations. The terminal can report the measurement results to the source cell through the configuration information for the measurement report. For example, referring to FIG. 11, the terminal (UE) can report the measurement results to the source node (S-node) through an L1 CSI-RS report message.

[0235] According to one embodiment of the present disclosure, a source node may receive a measurement report and determine a target node and / or a target cell of LTM. Furthermore, the source node may determine a target beam of the target cell. Furthermore, the source node may determine to perform LTM. The source node may transmit information (e.g., target cell candidate ID, beam to use of FIG. 11) to a terminal through an LTM cell switch command signal. The LTM cell switch command signal may include an ID of one of common cell configurations as a target cell (e.g., target cell candidate ID of FIG. 11). Furthermore, the LTM cell switch command signal may include target beam information (e.g., beam to use of FIG. 11) to be used by the terminal in the target cell. The LTM cell switch command signal may include a downlink RRC message, a DL MAC CE, and DCI.

[0236] According to one embodiment of the present disclosure, a terminal that has received information can check target cell configuration information of the indicated ID among common cell configurations, and apply the target cell configuration of the indicated ID to perform movement to the target cell of the indicated ID. In addition, according to one embodiment of the present disclosure, the terminal can perform a random access channel (RACH)-based or RACH-less (random access channel less) handover (HO) (RACH procedure) through target beam information included in a cell switch command signal. According to one embodiment of the present disclosure, the terminal can perform a process of aligning uplink synchronization and downlink synchronization during the handover process, and configuration information related to the synchronization process may be provided to the terminal in advance. Through the synchronization operation, the terminal can transmit a complete message to the target cell. For example, referring to FIG. 11, the terminal can transmit an RRCReconfigurationComplete message to the target cell. The complete message may include the target ID of the common cell configuration given in the cell switch command, and may include an indicator indicating that the movement was performed by LTM. This allows the target node to recognize that the terminal was moved by LTM through the indicator indicating that the movement was performed by LTM. Without the indicator indicating that the movement was performed by LTM, the target node may have difficulty understanding how the terminal performed the movement.

[0237] According to one embodiment of the present disclosure, the complete message may include a UL RRC message, a UL MAC CE, or a UCI (L1 control channel).

[0238] FIG. 12 is a diagram for explaining a case where a terminal performs a general handover based on a common cell setting according to one embodiment of the present disclosure.

[0239] For example, the example illustrated in FIG. 12 may be an example of a case where a common cell configuration is set in a terminal and the terminal performs a general handover using the common cell configuration.

[0240] According to one embodiment of the present disclosure, after receiving common cell configuration, the terminal may measure beams of a source cell and / or neighboring cells and / or those cells according to L1 measurement / report configuration and / or L3 RRM measurement / report configuration included in an RRCReconfiguration message including the common cell configuration or an RRCReconfiguration message after the common cell configuration. Then, the terminal may report the measurement result to the source cell through configuration information for the measurement report. For example, referring to FIG. 12, the terminal (e.g., the UE of FIG. 12) may report the measurement result to a source node (e.g., the S-node of FIG. 12) through an L1 CSI-RS report or an L3 measurement report.

[0241] According to one embodiment of the present disclosure, a source node may receive a measurement report and determine a target node and / or a target cell for a normal handover. Furthermore, the source node may determine a target beam of the target cell as needed (especially when a previous L1 measurement / reporting configuration is configured to measure the beam of the target cell). Furthermore, the source node may decide to perform a normal handover. The source node may instruct a terminal to perform a handover command with the information. The handover command signal may include an ID of one of the common cell configurations as the target cell. Furthermore, the handover command signal may include target beam information to be used by the terminal in the target cell. The handover command signal may include a downlink RRC message (e.g., RRCReconfiguration), a DL MAC CE, or DCI. From a signaling message perspective, the handover command of a normal handover and the cell switch command of the above-described LTM may have the same format. From a signal message perspective, if the formats of the handover command of a normal handover and the cell switch command of the above-described LTM are the same, the handover command of a normal handover and the cell switch command of the above-described LTM are the same in that they include a target cell ID, but whether it is a normal handover or an LTM can be distinguished depending on whether it includes target beam information in the target cell.A typical handover according to an embodiment of the present disclosure differs from a conventional Layer 3 typical handover in that a source node directly issues a handover command to a terminal without requesting a handover from the target node and receiving a response to the handover request. A typical handover according to an embodiment of the present disclosure can assume that the common cell settings of the terminal are always updated on a network basis and are instructed to the terminal. Therefore, the source node does not need to negotiate resource allocation with the target node at the time of the actual handover decision.

[0242] According to one embodiment of the present disclosure, a terminal that has received information can check target cell configuration information of an indicated ID (indicated by ID) from common cell configurations, and apply the target cell configuration of the indicated ID to perform movement to the target cell of the indicated ID. In addition, according to one embodiment of the present disclosure, if target beam information is included in a handover command, the terminal can perform a RACH (random access channel)-based or RACH-less (random access channel less) handover (HO) (RACH procedure) through the included target beam information. According to one embodiment of the present disclosure, the terminal can perform a process of aligning uplink synchronization and downlink synchronization during the handover process, and configuration information related to the synchronization process may be provided to the terminal in advance. Through the synchronization operation, the terminal can transmit a complete message to the target cell. For example, the terminal may transmit a completion message to the target cell via the HO Complete RRC msg, or the UL MAC CE, or the UCI. The complete message may include the target ID of the common cell configuration given in the handover command, and may include an indicator indicating that the movement is performed by a normal handover. This allows the target node to know that the terminal has moved by a normal handover through the indicator indicating that the movement is performed by LTM. If there is no indicator indicating that the movement is performed by LTM, it may be difficult for the target node to know how the terminal has moved.

[0243] According to one embodiment of the present disclosure, the complete message may include a UL RRC message, a UL MAC CE, or a UCI (L1 control channel).

[0244] FIG. 13 is a diagram for explaining a case where a terminal performs conditional handover (CHO) based on common cell settings according to one embodiment of the present disclosure.

[0245] For example, the example illustrated in FIG. 13 may be an example of a case where a terminal performs a conditional handover (CHO) using the common cell configuration in a situation where a common cell configuration is set in the terminal.

[0246] According to one embodiment of the present disclosure, after receiving a common cell configuration, the terminal can measure a source cell and / or a neighboring cell and / or a beam of the cells according to a CHO configuration included in an RRCReconfiguration message that included the common cell configuration. The measurement performed by the terminal according to the CHO configuration may be based on the assumption that a condition of the CHO configuration consists of a cell signal strength and / or a beam signal strength of the source cell and / or the neighboring cell. Then, the terminal can evaluate whether a condition associated with a specific target cell is fulfilled based on the measurement result, and if the condition is fulfilled, can perform CHO to the corresponding target cell.

[0247] According to one embodiment of the present disclosure, for a target cell that satisfies a condition, the terminal can check target cell configuration information among common cell configurations and apply the target cell configuration that satisfies the condition, thereby performing movement to the target cell that satisfies the condition. In addition, if target beam information is included in the target cell configuration, RACH-based or RACH-less HO can be performed using the included target beam information. According to one embodiment of the present disclosure, the terminal can perform a process of aligning uplink synchronization and downlink synchronization during a handover process, and related configuration information may be provided to the terminal in advance. Through the synchronization operation, the terminal can transmit a complete message (e.g., HO Complete RRC msg or UL MAC CE or UCI of FIG. 13) to the target cell. The complete message can include a target ID of the common cell configuration and an indicator indicating that the movement is performed by CHO. The target node can determine that the terminal has moved via CHO through an indicator indicating that the move was performed via CHO. If there is no indicator indicating that the move was performed via CHO, the target node may have difficulty determining how the terminal has moved.

[0248] According to one embodiment of the present disclosure, the complete message may include a UL RRC message, a UL MAC CE, or a UCI (L1 control channel).

[0249] According to one embodiment, when a terminal performs CHO, instead of immediately performing measurement and condition evaluation for CHO-related conditions after the mobility preparation phase of FIG. 13, the terminal may receive a signal from the network explicitly instructing CHO to be performed after the mobility preparation phase, and then begin measuring and evaluating conditions for the corresponding CHO target candidate cells. After that, if the condition for a specific candidate cell is satisfied, the terminal may perform CHO to the specific candidate cell that satisfies the condition. When the network explicitly instructs the terminal to perform CHO, the network may also indicate a specific candidate cell ID. When the terminal receives such a signal from the network, the network may perform measurement and condition evaluation for the indicated specific candidate cell, and if the condition is satisfied, the terminal may perform CHO to the specific candidate cell. The operations of measuring and evaluating conditions for the terminal's movement to a candidate cell can be equally applied not only to CHO but also to conditional LTM (where a specific candidate cell is configured and conditions based on radio signals to be performed for each candidate cell are given). For example, the terminal may perform condition measurement and condition evaluation of CLTM immediately after the mobility preparation phase, or may perform condition measurement and evaluation after receiving a separate CLTM execution instruction from the network after the mobility preparation phase.

[0250] Figures 14 and 15 illustrate operations related to maintenance of a given common cell configuration.

[0251] FIG. 14 is a diagram for explaining a case in which a common cell setting is updated when a source cell setting is changed according to one embodiment of the present disclosure.

[0252] According to one embodiment of the present disclosure, when a terminal receives common cell settings from a network and stores the received common cell settings, and a serving cell setting changes, the network can check whether the common cell settings have changed accordingly, and if a change is required, the network can instruct the terminal to update with the latest settings. As a result, the terminal maintains the latest target cell settings at a specific point in time desired by the network, and when the terminal performs movement, it can perform the movement without any issues with the target cell.

[0253] According to one embodiment of the present disclosure, the change of the source cell configuration may include, but is not limited to, the change of the configuration related to the addition / change / removal of the source cell managed by all source nodes and the addition / change / removal of secondary cells (Scells) corresponding to carrier aggregation (CA) when the source cell is designated as a special cell (spcell), including the addition / change / removal of a radio bearer, the addition / change / removal of a measurement configuration, etc. For example, referring to FIG. 14, the source node (S-node) can identify that the configuration of a Pcell (or any of a serving cell) has been changed. When the source node identifies that the configuration of the source cell has been changed or is about to be changed, the source node can, at its own discretion, perform a configuration modification request for all or some cells managed with a common cell configuration at its own discretion. To request a configuration modification, a source node may transmit an Xn message, an inter-node message, or an inter-CU message to the target node of each target cell for which the configuration modification is requested. The message transmitted by the source node to the target node may be the same message used when the common cell configuration was initially requested to be created. For example, referring to FIG. 14, a source node (e.g., S-node of FIG. 14) may transmit a handover request (e.g., HO req of FIG. 14) message to a target node (e.g., T-node 1, T-node-2 of FIG. 14).If the message transmitted by the source node to the target node is the same message used when requesting the creation of a common cell configuration, the message transmitted by the source node to the target node must include an indication requesting an update of the target cell configuration already given to the terminal (e.g., a modification indication in FIG. 14). The message transmitted by the source node to the target node may naturally include an ID of the terminal (UE ID), an ID of the target cell to be modified (e.g., a target cell of interest in FIG. 14), a serving cell configuration of the changed source cell (e.g., an updated serving cell config in FIG. 14), and an indication of a mobility scheme requesting an update (e.g., a mob scheme for update in FIG. 14). In particular, the indication of a mobility scheme requesting an update is necessary because, in the case of a specific mobility scheme, a target cell update may be required, and in the case of a specific mobility scheme, this may not be the case.

[0254] According to one embodiment of the present disclosure, a target node (e.g., T-node 1, T-node 2 of FIG. 14) that receives a message for a configuration modification request from a source node may write, in a delta configuration format, a changed portion of a target cell configuration previously written for a terminal based on a given updated serving cell configuration of a source cell. For example, referring to FIG. 14, the target node (e.g., T-node 1, T-node 2 of FIG. 14) may generate an updated target cell configuration. The target node (e.g., T-node 1, T-node 2 of FIG. 14) may return the updated target cell configuration to the source cell. In the present disclosure, the updated target cell configuration returned to the source cell may be referred to as a new target cell configuration. In addition, the information returned to the source cell may include indication information on a mobility method to which the new target cell configuration is applied. Instructions for the mobility scheme to which the new target cell configuration is applied can be included in Xn, inter-node, and inter-CU messages and transmitted to the source node. For example, referring to FIG. 14, a target node (e.g., T-node 1, T-node-2 in FIG. 14) can transmit a handover request response message (e.g., HO req ACK in FIG. 14) to the source node, the handover request response message including a terminal (UE) ID, an updated target cell configuration, and a mobility scheme (mob scheme) to which the new target cell configuration is applied.

[0255] According to one embodiment of the present disclosure, a source node that receives a message (e.g., an Xn, inter-node, inter-CU message) may collect updated target cell configurations from target nodes (T-node 1, T-node-2) from which the source node itself attempted a target cell change request, and then transmit the updated target cell configurations to a terminal in a common cell configuration field, including the changed target cell configurations and an ID that was previously associated with the common cell configuration field given to the terminal. Furthermore, according to one embodiment of the present disclosure, the new target cell configuration and ID association information may be associated with an indicator indicating an update. The new target cell configuration information (e.g., the updated candidate target cell configuration of FIG. 14) may be included in an RRCReconfiguration message and indicated to the terminal.

[0256] According to one embodiment of the present disclosure, a terminal receiving an RRCReconfiguration message compares a target cell ID associated with an update indicator included in a common cell configuration field with an updated target cell configuration ID that the terminal currently stores, and if the terminal stores a target cell configuration of the updated target cell configuration ID, changes it to the newly given updated target cell configuration and stores the updated target cell configuration. For example, referring to FIG. 14, the terminal (UE) can store an updated target cell configuration (e.g., the updated configuration of FIG. 14) in a common cell configuration (e.g., the candidate cell list of FIGS. 7 to 9). As a result, the terminal can manage common cell configurations with the most recent target cell configuration. After this, for example, the terminal can transmit an RRCReconfigurationComplete message to the source node, and the source node can receive the RRCReconfigurationComplete message and update the configuration information (e.g., the candidate cell list of FIGS. 7 to 9) maintained for the terminal (UE) and manage it with new configuration information.

[0257] According to one embodiment of the present disclosure, thereafter, the terminal can perform handover (movement) using a common cell configuration through a mobility method in a directed or set manner.

[0258] FIG. 15 is a diagram for explaining a case in which a terminal is requested to remove a target cell setting when resource allocation for mobility is not possible in a target node according to one embodiment of the present disclosure.

[0259] According to one embodiment of the present disclosure, even if a target node has previously allocated resources for movement for a specific terminal, the target node may need to release resources for future handovers due to excessive traffic in its own cell or resources for terminals served by the target node itself. To this end, the target node may need to support a signal to release the resources it has allocated for the terminal at any time.

[0260] Referring to Fig. 15, after the target node decides to remove the resources of a specific terminal, it can notify the source node of the terminal of the resource support interruption through an Xn, inter-node, or inter-CU message such as a HO (handover) cancel message. The message notifying the resource support interruption can include the terminal (UE) ID, the reason for resource recovery (e.g., traffic excessive, or operation for its own serving terminal only), the target cell ID (target cell ID (not candidate ID)) to which the resource recovery is applied, and the indication information of the mobility scheme (mob scheme for release) to which the resource recovery is applied.

[0261] According to one embodiment of the present disclosure, a source node that has received a message notifying of resource support interruption may transmit to a terminal, through an RRCReconfiguration message, a target cell release indicator in a common cell configuration field, and a target cell ID to be released.

[0262] According to one embodiment of the present disclosure, a terminal that has received a message (e.g., RRCReconfiguration of FIG. 15) from a source node can release target cells (that target cells) whose IDs are associated with release indicators in the terminal variables (in the Var) that the terminal itself is operating. Then, the terminal can transmit a message (e.g., RRCReconfigurationComplete of FIG. 15) to the source node.

[0263] According to one embodiment of the present disclosure, a source node that receives a message (e.g., RRCReconfigurationComplete of FIG. 15 ) from a terminal may release released configuration information among common cell configuration information for the terminal that transmitted the message (e.g., RRCReconfigurationComplete of FIG. 15 ). For example, referring to FIG. 15 , the source node (S-node) may update a candidate cell list (e.g., candidate cell list) for the terminal. As a result, the source node may keep the cell configuration information for the terminal up to date.

[0264] According to one embodiment of the present disclosure, when a RACH-less (random access channel less) handover (HO) related setting exists in a specific target cell setting of a common cell setting, a TA (timing advance) value may be required when instructing a terminal to move to a specific target cell or when the terminal performs a specific type of movement. A method for notifying the TA value when performing RACH-less HO for each movement type may be required. Here, the RACH-less HO related setting may mean at least one of the following.

[0265] - Rach-less HO indicator

[0266] - When performing RACH-less HO, an uplink (UL) resource indicator to be used for uplink transmission (UL transmission) in the target cell.

[0267] -- The UL resource indicator can be a CG (configured grant) setting or a dynamic grant setting.

[0268] -- In the case of CG, it indicates UL resources periodically allocated for UL transmission in the target cell, and may include information such as time and frequency information of UL resources, period information of UL allocation, transmission power during UL transmission, channel information (PUCCH or PUSCH) to be used during UL transmission, and beam information linked to CG to be considered during UL transmission in the target cell, such as SSB index or TCI state ID of the beam, and signal strength threshold value for verifying the validity of the beam, and in the case of dynamic grant, it may include information on a channel (PDCCH or PDSCH) to receive resources for UL transmission to be used in the target cell, SSB index or TCI state ID of the beam to receive the schedule, etc.

[0269] The way to tell the TA value is:

[0270] Opt 1. Along with the RACH-less HO configuration information of each common cell configuration, a TA value of a specific value can be included. Here, the specific value can mean the actual TA value, or it can use the N_{TA} value as a variable used in calculating the TA value. For example, the N_{TA} value can be set to 0, or it can include an instruction to use the TA value of the current source cell as is.

[0271] Opt 2. When performing target cell configuration including the RACH-less HO indicator of the common cell configuration, the TA value can be entered into the signal to perform the configuration.

[0272] For example, in a handover command indicating a general handover, in addition to including a target cell ID, a TA value or an N_{TA} value, or an instruction to use the TA of the source cell may be included and instructed to the terminal.

[0273] For example, in the case of CHO, a TA value indication can be performed through a separate DL signal, at which time, the ID of a specific target cell among the common cell settings to which the TA value is applied can be included, and additionally, a TA value or an N_{TA} value, or an instruction to use the TA of the source cell can be included and instructed to the terminal.

[0274] For example, in the case of LTM, as a method of acquiring early TA, the transmission of an RA preamble can be instructed from the source cell. This instruction can be given via a physical downlink control channel (PDCCH) (or downlink control indicator (DCI)) or a downlink (DL) MAC control element (CE), and the instruction can indicate the target of preamble transmission by including a specific target cell ID of a common cell configuration. A terminal receiving the instruction can transmit an RA preamble to the corresponding cell, and a node of the target cell that received the RA preamble can calculate a timing advance (TA) through the transmission. This calculated TA value can be transmitted to the source node as an inter-node message. The source node can transmit the TA value to the terminal by adding it to other target cell information in an LTM cell switch command. In another case, LTM may include a configuration for acquiring TA through terminal-based measurement in the configuration information associated with the target cell of the common target cell. The configuration for acquiring TA through terminal-based measurement may include specific RS configuration information for the target cell, allowing the terminal to acquire the TA value by measuring the corresponding RS. Therefore, when the source cell issues an LTM cell switch command to the terminal, if there is no separate TA value, the terminal can use the TA value it has measured and calculated by itself when moving to the corresponding target cell.

[0275] According to one embodiment of the present disclosure, in addition to the method of notifying the TA value, the TA value acquired by the above-described methods can be used for subsequent movement by always updating the TA value of the target cell configuration including the RACH-less HO indication of the common cell configuration, even if it is not used for immediate movement. The terminal always updates and stores the TA value indicated by the network as the TA value for the corresponding target cell, and thereafter, when the CHO condition is satisfied or a general handover indication (handover command) or an LTM cell switch command is given, the terminal can use the latest updated TA value when moving to the corresponding target cell. The process of acquiring the measurement-based TA of the terminal is also used to update the TA value of the corresponding target cell, and thereafter, when performing movement to the corresponding cell, the updated latest TA value can be used when performing the movement. Naturally, all movements referred to herein can be understood as a term meaning RACH-less HO in a target cell with a RACH-less HO indication.

[0276] According to one embodiment of the present disclosure, in the case of LTM, one of the beams included in the configuration of the CG included in the configuration of the RACH-less HO is a beam indicated to be used in the LTM cell switch command, and when performing UL transmission for the beam indicated in the cell switch command, it is checked whether the signal strength of the indicated beam is greater than or equal to the RSRP threshold for each beam in the configured grant (CG) configuration to determine whether the corresponding beam is valid for UL transmission. If the beam indicated by the LTM cell switch command is valid for UL transmission, a complete message can be transmitted to the target cell by performing UL transmission based on the configured grant (CG) of the corresponding beam, and DL / UL scheduling information can be received through PDCCH (physical downlink control channel) monitoring accordingly. At this time, beam information for PDCCH monitoring can be included in the RACH-less HO configuration of each target cell configuration.

[0277] The methods according to the embodiments described in the claims or specification of the present invention may be implemented in the form of hardware, software, or a combination of hardware and software.

[0278] 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 invention.

[0279] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they 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.

[0280] Additionally, the program may be stored in 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 invention 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 invention.

[0281] In the specific embodiments of the present invention described above, components included in the invention are expressed in the singular or plural form 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 invention is not limited to singular or plural components. Even components expressed in the plural form may be composed of singular elements, or even components expressed in the singular form may be composed of plural elements.

[0282] While the detailed description of the present invention has described specific embodiments, it is clear that various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims but also by equivalents thereof.

Claims

1. In a wireless communication system, a method performed by a terminal (user equipment), the method comprising: A step of receiving, from a base station, common handover configuration information commonly applied to a plurality of handover types for each of a plurality of candidate target cells; A step of receiving additional configuration information additionally used according to at least one handover type among the plurality of handover types from the base station; Step of identifying the trigger of handover; A step of identifying a handover type for the triggered handover among the plurality of handover types; and A method comprising a step of performing a procedure according to the identified handover type based on the common handover setting information and the additional setting information.

2. In paragraph 1, A method wherein the at least one handover type for which the additional configuration information is used includes at least one of a conditional handover (CHO) type or a handover type according to L1 / L2 triggered mobility (LTM).

3. In paragraph 2, A method in which the additional configuration information includes at least one of information regarding a condition for the CHO, information indicating whether a physical cell identity (PCI) for handover according to the LTM, a synchronization signal block (SSB), information indicating whether configuration for a candidate target cell is complete, configuration information for early uplink (UL) synchronization, or transmission configuration indicator (TCI) state information for downlink (DL) synchronization.

4. In paragraph 1, A method wherein the additional configuration information includes delta configuration information for changing some of the common handover configuration information to perform a handover according to at least one handover type.

5. In the first paragraph, the method: A step of receiving an ID of one target cell for the handover among the plurality of candidate target cells from the base station; and Further comprising a step of identifying the configuration information corresponding to the one target cell among the common handover configuration information and the additional configuration information based on the ID of the one target cell, A method wherein the common handover configuration information and the additional configuration information for each of the plurality of candidate target cells are mapped to an ID indicating each of the plurality of candidate target cells.

6. In paragraph 1, The step of identifying the trigger of the handover includes the step of receiving a command of the handover from the base station, A method wherein the command for the handover includes information for indicating the handover type.

7. In the first paragraph, the method: A step of receiving updated target cell configuration information, at least a portion of which is different from the common handover configuration information and the additional configuration information, from the base station; and A method further comprising the step of updating the common handover configuration information and the additional configuration information based on the updated target cell configuration information.

8. In the first paragraph, the method: A step of receiving, from the base station, an instruction for releasing configuration information for a target cell corresponding to at least one of the plurality of candidate target cells and an ID of the target cell to be subject to the configuration information release; and A method further comprising a step of deleting, based on the above indicator and the ID, the setting information corresponding to the target cell that is the target of the setting information release among the target cell setting information and the additional setting information.

9. In paragraph 1, The above common handover configuration information includes information about TA (timing advance), A method according to the above handover type, wherein the procedure includes a RACH-less (random access channel less, RACH-less) handover procedure based on information about the TA.

10. In paragraph 1, The common handover configuration information includes reference configuration information commonly applied to all or some of the plurality of candidate target cells and delta configuration information individually applied to each of the plurality of candidate target cells. A method wherein target cell setting information applied to each of the plurality of candidate target cells is identified based on a combination of the reference setting information and delta setting information corresponding to each of the plurality of candidate target cells.

11. In paragraph 10, The above reference setting information includes multiple reference settings separated by multiple directives, A method wherein the delta setting information corresponding to each of the plurality of candidate target cells is mapped to one of the plurality of reference settings.

12. In a wireless communication system, a method performed by a base station including a serving cell, the method comprising: A step of identifying at least one candidate target cell for handover of a user equipment; A step of transmitting a handover request message for handover of the terminal to at least one candidate target cell; A step of receiving, from the at least one candidate target cell, common target cell configuration information commonly applied to a plurality of handover types for each of the at least one candidate target cell and additional configuration information additionally used according to at least one handover type among the plurality of handover types; and A method comprising the step of transmitting the common handover setting information and the additional setting information to the terminal.

13. For terminals (user equipment): At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the terminal: Receive common handover configuration information commonly applied to multiple handover types for each of multiple candidate target cells from a base station, Receive additional configuration information additionally used according to at least one handover type among the plurality of handover types from the base station, Identify the trigger for the handover, Identifying a handover type for the triggered handover among the plurality of handover types, and A terminal that performs a procedure according to the identified handover type based on the common handover setting information and the additional setting information.

14. In paragraph 13, A terminal in which at least one handover type for which the additional configuration information is used includes at least one of a conditional handover (CHO) type or a handover type according to L1 / L2 triggered mobility (LTM).

15. In a base station including a serving cell: At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor so that the base station: Identify at least one candidate target cell for handover of a user equipment, Transmitting a handover request message for handover of the terminal to at least one candidate target cell; Receive common target cell configuration information commonly applied to a plurality of handover types for each of the at least one candidate target cell from the at least one candidate target cell and additional configuration information additionally used according to at least one handover type among the plurality of handover types, and A base station that transmits the common handover setting information and the additional setting information to the terminal.

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