Terminal and communication method

Abstract

To allow a terminal to recognize whether there is connectivity between candidate target cells in mobility and can appropriately perform mobility in a wireless communication system.SOLUTION: A terminal includes a receiving unit that receives information from a base station indicating whether there is connectivity between a source cell and each of the candidate target cells in the mobility and whether there is connectivity between the candidate target cells, and a control unit that performs predetermined processing for the mobility on candidate target cells that have connectivity with the source cell on the basis of the information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a terminal and a communication method in a wireless communication system. [Background technology]

[0002] 3GPP (3rd Generation Partnership Project) Release 18 (Rel-18) introduced Layer 1 / Layer 2 Triggered Mobility (LTM) to improve mobility performance in wireless communication systems. LTM is a technology that reduces handover delays and communication interruption times compared to conventional Layer 3-based mobility methods.

[0003] On the other hand, LTM in Rel-18 is limited to mobility between cells within the same gNB (CU (Central Unit)), and LTM between different gNBs (inter-CU) is not supported. This restriction limits the scenarios in which LTM can be applied, and may prevent sufficient performance improvement. In response to this, 3GPP Release 19 is considering extending LTM between inter-CUs. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 38.300 V18.5.0(2025-03) [Non-patent document 2] 3GPP TS 38.401 V18.5.0(2025-03) Summary of the Invention [Problem to be solved by the invention]

[0005] In a subsequent LTM, which is a form of LTM, i.e., a subsequent LTM performed after the initial LTM, a configuration in which there is no Xn interface between multiple candidate target nodes (gNBs) is assumed. In such a non-full mesh configuration, there is a possibility that the network cannot issue a cell switch command because there is no Xn connection between the candidate nodes to which the UE is to move.

[0006] Furthermore, in subsequent conditional LTM, since the execution of LTM is triggered by the UE, the UE itself needs to recognize the presence or absence of Xn connectivity between candidate nodes. However, in the past, it was not clearly defined how the UE should acquire and determine the Xn connectivity information, which could result in the UE being unable to properly determine whether to execute LTM. [Means for solving the problem]

[0007] The terminal in this embodiment includes a receiving unit that receives information from a base station indicating whether or not there is connectivity between a source cell and each of the candidate target cells in mobility and whether or not there is connectivity between the candidate target cells, and a control unit that performs predetermined processing for the mobility on candidate target cells that have connectivity with the source cell based on the information. [Effects of the Invention]

[0008] According to this embodiment, in mobility in wireless communication, a terminal can recognize whether or not there is connectivity between candidate target cells, and can appropriately perform mobility. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a wireless communication system according to an embodiment of the present invention. [Figure 2]A diagram showing the relationship between source nodes and candidate target nodes in mobility. [Figure 3] FIG. 2 is a sequence diagram showing an example of an operation procedure (1) of the communication system according to the present embodiment. [Figure 4] 1 is a diagram showing an example of the relationship between a source cell and a candidate target cell having an Xn interface in this embodiment. FIG. [Figure 5] FIG. 10 is a sequence diagram showing an example of an operation procedure (2) of the communication system according to the present embodiment. [Figure 6] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station according to the present embodiment. [Figure 7] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal according to the present embodiment. [Figure 8] FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station or a terminal according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present embodiment will be described below with reference to the drawings. Note that the embodiment described below is an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0011] In operation of the wireless communication system of this embodiment, existing technology may be used as appropriate. The existing technology is, for example, existing NR or LTE, but is not limited to existing NR or LTE. Furthermore, the term "LTE" used in this specification has a broad meaning including LTE-Advanced and systems subsequent to LTE-Advanced (e.g., NR) unless otherwise specified.

[0012] Furthermore, in the present embodiment described below, terms used in existing LTE, such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel), are used. This is for convenience of description, and similar signals, functions, etc. may be referred to by other names. Furthermore, the above-mentioned terms in NR correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, etc. However, even signals used in NR are not necessarily designated as "NR-".

[0013] Furthermore, in this embodiment, the duplex method may be a time division duplex (TDD) method, a frequency division duplex (FDD) method, or other methods (for example, flexible duplex, etc.).

[0014] Furthermore, in this embodiment, "configuring" radio parameters etc. may mean that predetermined values ​​are pre-configured, or that radio parameters notified from a base station or a terminal are set.

[0015] (System Configuration) Fig. 1 is a diagram for explaining a wireless communication system in this embodiment. As shown in Fig. 1, the wireless communication system in this embodiment includes a base station 10 and a terminal 20. Although Fig. 1 shows one base station 10 and one terminal 20, this is an example, and there may be a plurality of each.

[0016] The base station 10 is a communication device that provides one or more cells and performs wireless communication with the terminal 20. The physical resources of a wireless signal are defined in the time domain and the frequency domain, and the time domain may be defined by the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols, and the frequency domain may be defined by the number of subcarriers or the number of resource blocks. Furthermore, a TTI (Transmission Time Interval) in the time domain may be a slot, or a TTI may be a subframe.

[0017] The base station 10 transmits a synchronization signal and system information to the terminal 20. The synchronization signal is, for example, NR-PSS and NR-SSS. The system information is transmitted, for example, via the NR-PBCH and is also referred to as broadcast information. The synchronization signal and system information may be referred to as an SSB (SS / PBCH block). As shown in FIG. 1 , the base station 10 transmits control signals or data to the terminal 20 via DL (Downlink) and receives control signals or data from the terminal 20 via UL (Uplink). Both the base station 10 and the terminal 20 are capable of transmitting and receiving signals by performing beamforming. Furthermore, both the base station 10 and the terminal 20 are capable of applying MIMO (Multiple Input Multiple Output) communication to DL or UL. Furthermore, both the base station 10 and the terminal 20 may communicate via a secondary cell (SCell) and a primary cell (PCell) using Carrier Aggregation (CA). Furthermore, the terminal 20 may perform communication via a primary cell of the base station 10 and a primary secondary cell group cell (PSCell: Primary SCG Cell) of another base station 10 using DC (Dual Connectivity).

[0018] The terminal 20 is a communication device equipped with a wireless communication function, such as a smartphone, a mobile phone, a tablet, a wearable terminal, or an M2M (Machine-to-Machine) communication module. As shown in FIG. 1, the terminal 20 receives control signals or data from the base station 10 via DL and transmits control signals or data to the base station 10 via UL, thereby utilizing various communication services provided by the wireless communication system. The terminal 20 also receives various reference signals transmitted from the base station 10 and measures the propagation path quality based on the reception results of the reference signals. The terminal 20 may also be referred to as a UE, and the base station 10 may also be referred to as a gNB.

[0019] In a subsequent LTM, which is a form of LTM, that is, a subsequent LTM performed after movement by an initial LTM, a configuration is assumed in which an Xn interface does not exist between candidate target nodes (for example, between candidate target nodes 1 and 4 and between candidate target nodes 2 and 3), as shown in FIG. 2. For example, as shown in FIG. 2, if a UE performs mobility from a source node to candidate target node 1 and then further performs mobility by LTM from candidate target node 1 to another candidate target node 4, if an Xn interface does not exist between candidate target node 1 and another candidate target node 4, the network may not be able to send a cell switch command to the UE.

[0020] Furthermore, in subsequent conditional LTM, since the execution of LTM is triggered by the UE, when the UE moves from one candidate target node to another, the UE needs to recognize whether or not there is Xn connectivity between the candidate target nodes. However, in the past, it was not clearly defined how the UE should acquire and determine the Xn connectivity information, which may result in the inability to properly determine whether or not to execute LTM.

[0021] According to this embodiment, in mobility with LTM, when a UE moves between candidate target cells, it can recognize whether there is Xn connectivity between those candidate target nodes.

[0022] As a result, in LTM mobility, the UE can monitor the LTM execution conditions by preferentially or limiting candidate cells and / or beams that have Xn connectivity with the source cell. Furthermore, it is possible to perform LTM by preferentially selecting candidate cells and / or beams that have Xn connectivity with the source cell as targets from multiple candidates that satisfy the execution conditions. As a result, the risk of LTM failure that may occur when targeting a candidate target node that does not have Xn connectivity is reduced, enabling appropriate mobility control.

[0023] The present embodiment will be described below.

[0024] The communication system in this embodiment supports LTM. LTM may be subsequent conditional LTM, conditional LTM, or subsequent conditional LTM. LTM is an example of mobility (for example, cell switching).

[0025] In this embodiment, the source or candidate target cell in mobility may be replaced by a beam or both a cell and a beam. For example, in LTM, the UE 20 may switch cells or beams, or may switch both cells and beams simultaneously.

[0026] According to this embodiment, the gNB (base station) 10 may be configured to include Xn connectivity information regarding connections of Xn interfaces between cells or nodes in an RRCReconfiguration message transmitted to the UE 20. The Xn connectivity information may include, for example, information indicating the presence or absence of Xn connectivity between the source cell and each of the candidate target cells and / or the presence or absence of Xn connectivity between the candidate target cell and another candidate target cell or the source cell.

[0027] Fig. 3 is a sequence diagram showing an example of an operation procedure of the communication system in this embodiment. Fig. 4 is a diagram showing an example of the relationship between a source cell and candidate target cells having an Xn interface according to this embodiment.

[0028] As shown in Figure 3, in step S11, the gNB 10 sends an RRCReconfiguration message including Xn connectivity information to the UE 20. The Xn connectivity information may include a list of other cells that have Xn connectivity with the predetermined cell. The predetermined cell may be, for example, the source cell (cell 0) or at least one of the candidate target cells 1-4 shown in Figure 4.

[0029] In the example shown in FIG. 3, the list of cells having Xn connectivity with the source cell includes candidate target cell 1, candidate target cell 2, candidate target cell 3, and candidate target cell 4.

[0030] The list of cells having Xn connectivity with candidate target cell 1 includes candidate target cell 2, candidate target cell 3 and the source cell (cell 0).

[0031] The list of cells having Xn connectivity with candidate target cell 2 includes candidate target cell 1, candidate target cell 4, and the source cell (cell 0).

[0032] The list of cells having Xn connectivity with candidate target cell 3 includes candidate target cell 1, candidate target cell 4 and the source cell (cell 0).

[0033] The list of cells having Xn connectivity with candidate target cell 4 includes candidate target cell 2, candidate target cell 3 and the source cell (cell 0).

[0034] In this embodiment, at least one of the above lists may be included.

[0035] According to the above-described embodiment, by including Xn connectivity information in the RRCReconfiguration message that gNB 10 transmits to UE 20, UE 20 can determine whether or not there is Xn connectivity between each candidate target cell or between the UE 20 and the source cell.

[0036] 5 is a sequence diagram showing an example of an operation procedure of LTM in the communication system according to this embodiment. In FIG. 5, an example of a process in which the UE 20 switches from a source cell of a source gNB 10A to a candidate target cell of a candidate target gNB 10B is shown.

[0037] As shown in FIG. 5, in step S21, LTM preparation is performed.

[0038] After the LTM preparation is completed, the UE 20 may perform one or more of the operations from step S22A to step S22D based on the Xn connectivity information.

[0039] In step S22A, the UE 20 performs early synchronization preferentially or only with candidate target cells that have Xn connectivity with the source cell.

[0040] In step S22B, the UE 20 performs CSI or L1 measurements preferentially or only on candidate target cells that have Xn connectivity with the source cell.

[0041] In step S22C, the UE 20 performs monitoring of the LMT execution conditions preferentially or only for candidate target cells that have Xn connectivity with the source cell.

[0042] In step S22D, if multiple candidate target cells satisfy the LTM execution condition, the UE 20 performs LTM preferentially or only for candidate target cells that have Xn connectivity with the source cell.

[0043] In step S23, the UE 20 performs a first uplink transmission.

[0044] For example, the following operations may be added to steps S22A to S22D in FIG. 5, or the following operations may be substituted for any of steps S22A to S22D.

[0045] In LTM, L1 measurements or L1 measurement reports may be deactivated for candidate target cells that do not have Xn connectivity.

[0046] After the LTM failure, the UE 20 performs cell selection, and if the selected cell is a candidate target cell, it can perform LTM fast recovery. For LTM fast recovery, the UE 20 may preferentially select candidate target cells that have Xn connectivity with the source cell in the cell selection, or may select only such candidate target cells.

[0047] After the LTM failure, the UE 20 performs cell selection and can perform LTM fast recovery if the selected cell is a candidate target cell. The UE 20 may perform LTM fast recovery preferentially for candidate target cells that have Xn connectivity with the source cell, or may perform LTM fast recovery only for the candidate target cells.

[0048] According to the above-described embodiment, in LTM mobility, when a UE moves between candidate target cells, it can know whether Xn connectivity exists between those candidate target nodes.

[0049] As a result, in LTM mobility, the UE can monitor the LTM execution conditions by preferentially or limiting candidate cells and / or beams that have Xn connectivity with the source cell. Furthermore, it is possible to perform LTM by preferentially selecting candidate cells and / or beams that have Xn connectivity with the source cell as targets from multiple candidates that satisfy the execution conditions. As a result, the risk of LTM failure that may occur when targeting a candidate target node that does not have Xn connectivity is reduced, enabling appropriate mobility control.

[0050] (Device configuration) Next, a description will be given of an example of the functional configuration of the base station (gNB) 10 and the terminal (UE) 20 that execute the processes and operations described above. The base station 10 and the terminal 20 include functions for implementing the above-described embodiments. However, the base station 10 and the terminal 20 may each include only a part of the functions in the embodiments.

[0051] <Base station (gNB)> Fig. 6 is a diagram showing an example of the functional configuration of the base station 10 in this embodiment. As shown in Fig. 6, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Fig. 6 is merely an example. The names of the functional divisions and functional units may be any as long as they can perform the operations in this embodiment. The transmitting unit 110 and the receiving unit 120 may be collectively referred to as a communication unit.

[0052] The transmitter 110 includes a function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The transmitter 110 also transmits setting information, instructions, notifications, etc. related to a low-power wake-up signal to the terminal 20. The transmitter 110 also transmits notifications related to switching of monitoring operations to the terminal. The receiver 120 includes a function of receiving various signals transmitted from the terminal 20 and acquiring, for example, information of higher layers from the received signals. The transmitter 110 also has a function of transmitting PSS, SSS, PBCH, DL / UL control signals, etc. to the terminal 20. The receiver 120 also receives inter-network node messages from other network nodes.

[0053] The setting unit 130 stores preset setting information and various setting information to be transmitted to the terminal 20. The content of the setting information is, for example, information on the operations explained in the embodiments.

[0054] The control unit 140 controls the settings, instructions, and notifications related to the operations described in the embodiments. The function unit related to signal transmission in the control unit 140 may be included in the transmitting unit 110, and the function unit related to signal reception in the control unit 140 may be included in the receiving unit 120.

[0055] <Device (UE)> Fig. 7 is a diagram showing an example of the functional configuration of the terminal 20 in this embodiment. As shown in Fig. 7, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 7 is merely an example. The names of the functional divisions and functional units may be any as long as they can execute the operations in this embodiment. The transmitting unit 210 and the receiving unit 220 may be collectively referred to as a communication unit.

[0056] The transmitter 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The transmitter 210 also transmits capability information in a low-power wake-up signal to the base station 10. The receiver 220 wirelessly receives various signals and acquires higher layer signals from the received physical layer signals. The receiver 220 also has a function of receiving PSS, SSS, PBCH, DL / UL / SL control signals, etc. transmitted from the base station 10. The receiver 220 also receives paging notification information and setting information, instructions, and notifications related to the low-power wake-up signal from the base station 10. For example, the receiver 220 receives a low-power wake-up signal from the base station 10. The setting unit 230 stores various setting information received by the receiver 220 from the base station 10. The setting unit 230 also stores setting information that is set in advance. The content of the setting information is, for example, information on the operations described in the embodiments.

[0057] As described in the embodiments, the control unit 240 controls settings, instructions, and notifications related to the operations described in the embodiments. A functional unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and a functional unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0058] (Hardware configuration) The block diagrams (FIGS. 6 and 7) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by hardware, software, or a combination of these. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized by using one device that is physically or logically coupled, or may be realized by using two or more physically or logically separated devices that are connected directly or indirectly (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining the one device or the multiple devices with software.

[0059] For example, a base station, a terminal, a network node, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 8 is a diagram illustrating an example of the hardware configuration of a base station and a terminal according to an embodiment of the present disclosure. The above-described base station 10 and terminal 20 may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0060] In the present disclosure, the term "apparatus" may be interchangeable with any two terms selected from a set of terms such as circuit, device, unit, module, chip, means, etc. The hardware configurations of the base station 10 and the terminal 20 may be configured to include one or more of the devices shown in the drawings, or may be configured to exclude some of the devices.

[0061] Each function in the base station 10 and the terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001, memory 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls the reading, writing, or both reading and writing of data in the memory 1002 and storage 1003.

[0062] The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, a baseband signal processing unit, a call processing unit, etc. may be realized by the processor 1001. Although only one processor 1001 is shown in the figure, there may be multiple processors.

[0063] The processor 1001 also reads programs (program codes), software modules, data, etc. from the storage 1003, the communication device 1004, or both the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes in accordance with the programs. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 401 of the terminal 20 may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and similar implementations may be made for other functional blocks. While the above-described various processes have been described as being executed by a single processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line, or may be provided to the computer via the communication device 1004, for example.

[0064] The present disclosure also provides a computer program product including a computer program, which may implement the steps of the methods described in the above embodiments when the computer program is executed by a computer (e.g., the processor 1001).

[0065] The memory 1002 is a computer-readable recording medium and may be configured, for example, as a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), or a combination of at least two of these. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), or the like. The memory 1002 can store executable programs (program codes), software modules, and the like for implementing a wireless communication method according to an embodiment of the present disclosure.

[0066] Storage 1003 is a computer-readable recording medium, and may be, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, or a combination of at least two of these. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned storage medium may be, for example, memory 1002, storage 1003, or a database, server, or other appropriate medium including both memory 1002 and storage 1003.

[0067] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via a wired network, a wireless network, or both wired and wireless networks, and is also referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, or a combination of at least two of these. For example, a transmitting / receiving antenna, an amplifier unit, a transmitting / receiving unit, or a transmission path interface may be realized by the communication device 1004. The transmitting / receiving unit may be implemented as a transmitting unit and a receiving unit that are physically or logically separated.

[0068] The input device 1005 is an input device that accepts input from the outside (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, or a combination of at least two of these). The output device 1006 is an output device that outputs to the outside (for example, a display, a speaker, an LED lamp, or a combination of at least two of these). The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0069] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0070] Furthermore, base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), a graphics processing unit (GPU), a neural processing unit (NPU), or a combination of at least two of these, and some or all of the functional blocks may be realized by the hardware. For example, processor 1001 may be implemented using at least one of these pieces of hardware.

[0071] <Additional notes> (Additional note 1) a receiving unit that receives, from a base station, information indicating whether or not there is connectivity between a source cell and each of candidate target cells in mobility and whether or not there is connectivity between the candidate target cells; A terminal comprising: a control unit that performs a predetermined process for the mobility for a candidate target cell that has connectivity with the source cell based on the information. (Additional note 2) The terminal according to Supplementary Item 1, wherein the control unit performs the predetermined process preferentially for candidate target cells that have connectivity with the source cell based on the information. (Additional note 3) The terminal according to Supplementary Item 1, wherein the control unit executes the predetermined processing only for candidate target cells that have connectivity with the source cell based on the information. (Additional note 4) The terminal according to Supplementary Item 1, wherein the predetermined processing is initial synchronization, CSI (Channel State Information) measurement, L1 (Layer 1) measurement, monitoring of the mobility execution conditions, or execution of the mobility when the execution conditions are met. (Additional note 5) The terminal according to Supplementary Item 1, wherein the mobility is mobility by LTM (Layer 1 / Layer 2 Triggered Mobility). (Additional note 6) A communication method performed by a terminal, comprising: receiving information indicating whether there is connectivity between a source cell and each of candidate target cells in a mobility scenario and whether there is connectivity between the candidate target cells; A communication method comprising a step of performing a predetermined process for the mobility for a candidate target cell that has connectivity with the source cell based on the information.

[0072] With any of the above configurations, when a terminal moves between candidate target cells during LTM mobility, it can recognize whether or not Xn connectivity exists between those candidate target nodes. During LTM mobility, the terminal can monitor the LTM execution conditions by preferentially or limiting candidate cells and / or beams that have Xn connectivity with the source cell. Furthermore, it is possible to execute LTM by preferentially selecting candidate cells and / or beams that have Xn connectivity with the source cell as targets from among multiple candidates that satisfy the execution conditions. As a result, the risk of LTM failure, which may occur when targeting candidate target nodes that do not have Xn connectivity, is reduced, enabling appropriate mobility control.

[0073] (Supplementary explanation of the embodiment) Although the present embodiment has been described above, the disclosed invention is not limited to such an embodiment, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention; matters described in two or more items may be used in combination as needed, and matters described in one item may apply to matters described in another item (unless inconsistent). The boundaries between functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of the processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, the base station 10 and terminal 20 have been described using functional block diagrams. However, such devices may be implemented using hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to this embodiment and the software operated by the processor of the terminal 20 according to this embodiment may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server or any other suitable storage medium.

[0074] The aspects / embodiments described in the present disclosure may be categorized as Long Term Evolution (LTE), LTE-Advanced (LTE-A), International Mobile Telecommunications-Advanced (IMT-Advanced), 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 5G-Advanced (5G-A), 6th generation mobile communication system (6G), xth generation mobile communication system (x is, for example, an integer or a decimal number)), Future Radio Access (FRA), New Radio (NR), New radio access (NX), Future generation radio access (FX), Open Radio Access Network (O-RAN), Wideband Code Division Multiple Access (W-CDMA) (registered trademark), Global System for Mobile communications (GSM) (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) Engineers) 802.11, IEEE802.11x (where x is any character string such as b, a, g, n, ac, ax, be, or bn, and when x=n it is called Wi-Fi4, when x=ac it is called Wi-Fi5, when x=ax it is called Wi-Fi6 or Wi-Fi6E, when x=be it is Wi-Fi7, and when x=bn it is called Wi-Fi8, etc. Wi-Fi is a registered trademark.), IEEE802.16 (WiMAX (registered trademark), IEEE802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), network virtualization technology (e.g., NFV (Network Function Virtualization), SFC (Service Function Chaining), SDN (Software Defined Networking)), or LPWA (Low Power Wide Area). Furthermore, each aspect / embodiment described in the present disclosure may be applied to a system based on a combination of at least two of these technologies. Furthermore, "based on" naturally refers not only to a system that uses the technology, but also to a system that uses an extension or modification of the technology.

[0075] In the present disclosure, any two terms selected from a set of terms such as "base station (BS)", "radio base station", "fixed station (fixed station)", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point (AP)", "transmission point (TP)", "reception point (RP)", "transmission / reception point (TRP)", "radio unit (RU)", "remote unit (RU)", "control unit (CU)", "distributed unit (DU)", "remote radio head (RRH)", "node", "gateway", "terrestrial base station", "stratospheric base station", "unmanned aerial vehicle", "high altitude platform station (HAPS)", "airborne platform", "panel", "cell", "radio access network (RAN)", and "network" may be used interchangeably.

[0076] Each cell accommodated by a base station may be referred to by terms such as a macro cell, a small cell, a femto cell, a pico cell, a serving cell, or a super cell. In the present disclosure, any two terms selected from a set of terms such as "cell," "sector," "cell group," "carrier," "component carrier," "cluster," "bandwidth part (BWP)," and "carrier bandwidth" may be used interchangeably.

[0077] In the present disclosure, any two terms selected from the set of terms such as "Mobile Station (MS)", "user terminal", "User Equipment (UE)", "Device", "Module" and "Terminal" may be used interchangeably.

[0078] A terminal may be referred to as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, router (e.g., home router, mobile router, etc.), TCU (Telematics Control Unit), or some other suitable terminology.

[0079] The base station and the terminal may each be composed of one or more devices. The devices constituting at least a portion of the base station and the terminal may be called a transmitting device, a receiving device, a communication device, etc. Note that the devices constituting at least a portion of the base station and the terminal may be, for example, an object itself, such as a vehicle, a transport vehicle, an automobile, a motorcycle, a bicycle, a connected car, an excavator, a bulldozer, a wheel loader, a dump truck, a forklift, a train, a bus, a handcar, a rickshaw, a ship and other watercraft, an airplane, a rocket, an unmanned aerial vehicle, a stratospheric base station (e.g., a High Altitude Platform Station (HAPS)), an artificial satellite (e.g., a Low Earth Orbit (LEO) satellite, a Medium Earth Orbit (MEO) satellite, a Geostationary Earth Orbit (GEO) satellite), a drone (registered trademark), a multicopter, a quadcopter, a balloon, or an Internet of Things (IoT) device (e.g., a smart meter, a sensor), or may include, but are not limited to, an object or device mounted on the object. Furthermore, the object may be a moving object (hereinafter referred to as a "moving object"; this does not exclude the case where the moving object is in a stationary state where it is not moving), or may be a fixedly positioned object (hereinafter referred to as a "non-moving object").

[0080] Furthermore, a base station in the present disclosure may be read as a terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a terminal is replaced with communication between multiple terminals (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)) or communication of a non-terrestrial network (NTN). In this case, the terminal 20 may be configured to have at least some of the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "sidelink") or terms corresponding to NTN (for example, feeder link or service link). For example, an uplink channel or a downlink channel may be read as a sidelink channel.

[0081] The present disclosure is also applicable to cases where at least some of the devices constituting the base station and the terminal operate outside the earth (for example, in the atmosphere or outer space).

[0082] In addition, the term "terminal" in the present disclosure may be read as "base station." In this case, the base station 10 may be configured to have the functions of the terminal 20 described above.

[0083] The notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI) and Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB) and System Information Block (SIB))), other signals, or a combination of at least two of these. Note that the physical layer signaling may be referred to as Layer 1 (L1) control information. The MAC signaling may be referred to as a MAC Control Element (CE) or a MAC Protocol Data Unit (PDU), for example. Furthermore, the RRC signaling may be referred to as an RRC message or an information element (IE) in the RRC message. The RRC message may be, for example, a message used for controlling an RRC connection (for example, setup, reconfiguration, establishment, reestablishment, release, or resume), mobility, a measurement report, or notification of a terminal's capabilities, or may be an information element within the message. Furthermore, notification of information may be explicit or implicit. Note that explicit notification of certain information means notification of the certain information itself, and implicit notification of certain information may mean notification of information other than the certain information, or may mean that the certain information is considered to have been notified when a certain condition is satisfied.Furthermore, notification of information may include not only notification between the same layers of different devices (e.g., between a lower layer or an upper layer of the base station 10 and the terminal 20) but also notification between different layers in the same or different devices (e.g., between a lower layer and an upper layer in the base station 10 or the terminal 20). Furthermore, notification of information from one device to another device may be performed via one or more devices. Regarding any information (e.g., a variable, a constant, a parameter, a setting) described in the present disclosure, even if not specifically stated in the above embodiments, information indicating / specifying (or related to) the any information (value) may be notified from any first device (e.g., a terminal / base station) to any second device (e.g., a base station / terminal).

[0084] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0085] In the present disclosure, a specific operation described as being performed by a base station may be performed by its upper node or by some of its upper nodes (e.g., CU, RU, or DU, etc.) in some cases. It is clear that various operations performed for communication with a terminal in a RAN or core network may be performed by at least some of the base station and other network nodes other than the base station. The other network node may be one node or a combination of multiple nodes. The network node is, for example, a node provided in various core networks such as EPC (Evolved Packet Core) and 5GC (5G Core Network), and provides one or more network functions (NF: Network Functions), but is not limited to this.

[0086] Furthermore, in the present disclosure, the operation of "a terminal receives information from a base station" accompanies the operation of "the base station transmits the information to the terminal," "the base station generates the information," or both. Similarly, the operation of "a terminal transmits information to a base station" accompanies the operation of "the base station receives the information from the terminal." Furthermore, the operation of "a terminal is configured to ..." or "configure UE to ..." may include the operation of "a base station transmits configuration information regarding the configuration of the terminal" and the operation of "a terminal configures a predetermined operation based on the configuration information."

[0087] Each aspect / embodiment described in the present disclosure may be used alone, in combination, or switched depending on the implementation.

[0088] The present disclosure has been described above, but it is for illustrative purposes only, and the present invention is not limited to the aspects / embodiments described in the present disclosure. The present disclosure can be implemented in modified and altered forms without departing from the spirit of the invention. The present disclosure and its modifications and alterations are included in the scope of the present invention and its equivalents.

[0089] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0090] The radio resource may be defined by a combination of resource units in one or more domains, such as the time domain, the frequency domain, the spatial domain, the code domain, and the power domain.

[0091] For example, resources in the time domain may be defined by one or more time units. The one or more time units may include, but are not limited to, a radio frame, a subframe, a slot, a symbol, a transmission time interval (TTI), or a combination of at least two of these. The time unit may be a fixed-length time unit independent of numerology, a variable-length time unit dependent on numerology, or both. Examples of fixed-length time units include, but are not limited to, a subframe consisting of one or more slots and a radio frame including multiple subframes. Examples of variable-length time units include, but are not limited to, a symbol and a slot including a fixed number of symbols. A certain time unit may be divided into shorter time units. Examples of shorter time units include, but are not limited to, a minislot consisting of fewer symbols than the number of symbols constituting a slot. The above-described time units may include, for example, time units used as units for scheduling, link adaptation, etc. Furthermore, any time unit in the present disclosure may be read as another time unit.

[0092] Numerology is a parameter that defines the physical layer structure, and may be a parameter based on at least one of subcarrier spacing (SCS), symbol length, cyclic prefix length, and sampling time, for example.

[0093] Resources in the frequency domain may be defined, for example, by one or more frequency units. The one or more frequency units may include, for example, subcarriers, resource blocks (RBs), bandwidth parts (BWPs), carrier bandwidths, or a combination of at least two of these, but the terminology of the frequency units is not limited to these. The number of subcarriers included in a frequency unit may be a fixed number regardless of numerology, or may be a variable number that changes depending on numerology. For example, an RB is composed of a predetermined number of consecutive subcarriers in the frequency domain, and the number of subcarriers included in the RB may be the same regardless of numerology, for example, 12, but is not limited to this. A BWP may be composed of, for example, one or more consecutive RBs within a certain carrier bandwidth, but is not limited to this. One or more BWPs may be configured within one carrier for terminal 20, and at least one of the BWPs may be activated. Any frequency unit in the present disclosure may be interchangeable with another frequency unit.

[0094] Furthermore, resources in both the time domain and the frequency domain may be defined by one or more time / frequency units each consisting of a time unit and a frequency unit, such as, but not limited to, a resource element (RE) consisting of one symbol and one subcarrier, a resource element group (REG) consisting of a predetermined number of REs, or a control resource set (CORESET) consisting of a predetermined number of symbols and a predetermined number of RBs.

[0095] Furthermore, resources in the spatial domain may be defined, for example, by one or more spatial units, including, but not limited to, a beam, a layer of MIMO (Multi-Input Multi-Output), an antenna port, or a combination of at least two of these.

[0096] Furthermore, the resources in the code domain may be defined by one or more code units, such as, but not limited to, a cyclic shift (CS), an orthogonal cover code (OCC), or a combination thereof.

[0097] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0098] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc. [Explanation of symbols]

[0099] 10 base station 110 Transmitter 120 Receiver 130 Setting section 140 Control Unit 20 terminals 210 Transmitter 220 Receiving unit 230 Setting Section 240 Control Unit 1001 processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication equipment 1005 Input Device 1006 Output Device

Claims

1. a receiving unit that receives, from a base station, information indicating whether or not there is connectivity between a source cell and each of candidate target cells in mobility and whether or not there is connectivity between the candidate target cells; A terminal comprising: a control unit that performs a predetermined process for the mobility for a candidate target cell that has connectivity with the source cell based on the information.

2. The terminal according to claim 1 , wherein the control unit performs the predetermined process preferentially on candidate target cells that have connectivity with the source cell based on the information.

3. The terminal according to claim 1 , wherein the control unit executes the predetermined process only for candidate target cells that have connectivity with the source cell based on the information.

4. The terminal according to claim 1 , wherein the predetermined processing is initial synchronization, CSI (Channel State Information) measurement, L1 (Layer 1) measurement, monitoring of an execution condition of the mobility, or execution of the mobility when the execution condition is satisfied.

5. The terminal according to claim 1 , wherein the mobility is mobility by LTM (Layer 1 / Layer 2 Triggered Mobility).

6. A communication method performed by a terminal, comprising: receiving information indicating whether there is connectivity between a source cell and each of candidate target cells in a mobility scenario and whether there is connectivity between the candidate target cells; A communication method comprising a step of performing a predetermined process for the mobility for a candidate target cell that has connectivity with the source cell based on the information.

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