Base station and communication method

Abstract

This base station comprises: a control unit that determines whether to perform mobility; and a transmission unit that transmits, to a target base station which manages a target cell in the mobility, information indicating whether switching to the target cell is or is not accompanied by changing a secondary node.

Description

Base station and communication method

[0001] The present invention relates to a base station and a communication method in a communication system.

[0002] In 3GPP (3rd Generation Partnership Project) (registered trademark), technologies related to Inter-CU MCG LTM (Lower layer Triggered Mobility) are being studied to enhance mobility control for user equipment (UE) in 5G networks. In 3GPP Release 19 (Rel.19), scenarios for implementing Inter-CU MCG LTM with or without SN (Secondary Node) modification are under discussion.

[0003] 3GPP TS 38.473 V18.5.0 (2025-03)3GPP TS 38.423 V18.5.0 (2025-03)

[0004] Conventionally, when mobility types with SN modification (e.g., cell handover) and mobility without SN modification for the same target cell are simultaneously configured as candidates, the source-side DU (Distributed Unit) cannot determine which mobility type should be applied. Furthermore, conventionally, no method has been established for notifying the target node side which mobility type is to be used. Therefore, there is a risk that mobility cannot be performed appropriately.

[0005] The base station according to the present embodiment comprises: a control unit configured to determine whether to perform mobility; and a transmission unit configured to transmit, to a target base station that manages a target cell in the mobility, information indicating whether handover to the target cell involves modification of a secondary node or does not involve modification of the secondary node.

[0006] According to the present embodiment, appropriate mobility can be implemented in consideration of whether modification of a secondary cell is involved.

[0007] This is a diagram illustrating an example of a communication system. This is a diagram illustrating an example of a communication system in a roaming environment. This is a diagram showing the information elements included in a conventional Xn Cell Switch Notification message. This is a sequence diagram showing an example of the operation procedure of the communication system in this embodiment. This is a diagram showing an example of the information elements included in an F1AP CU-DU / DU-CU Cell Switch Notification message in this embodiment. This is a diagram showing an example of the information elements included in an XnAP Cell Switch Notification message in this embodiment. This is a diagram showing an example of the functional configuration of a base station and network node in this embodiment. This is a diagram showing an example of the functional configuration of a terminal in this embodiment. This is a diagram showing an example of the hardware configuration of a base station and terminal in this embodiment. This is a diagram showing an example of the vehicle configuration in this embodiment.

[0008] This embodiment will be described below with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention applies are not limited to those described below.

[0009] The communication system of this embodiment operates using existing technology. Existing technology is, for example, wireless communication technology based on communication standards such as the 3GPP standard. Existing technology is, for example, NR (New Radio), but is not limited to existing NR. As used herein, the term "NR" has a broad meaning that includes NR (5G) and later systems (e.g., 6G), unless otherwise specified.

[0010] In this embodiment, "configuring" wireless parameters means either pre-configuring predetermined values, or configuring wireless parameters notified by the network node 30 or terminal 20.

[0011] Figure 1 is a diagram illustrating an example of a communication system. As shown in Figure 1, the communication system consists of a terminal 20 (UE) and multiple network nodes 30. Hereafter, one network node 30 will be assumed to correspond to each function, but one network node 30 may implement multiple functions, or multiple network nodes 30 may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0012] The RAN (Radio Access Network) is a network node 30 having wireless access functionality, which may include a base station 10, and is connected to the UE, AMF (Access and Mobility Management Function), and UPF (User plane function). The AMF is a network node 30 having functions such as RAN interface termination, NAS (Non-Access Stratum) termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 interconnected with the DN (Data Network) and having functions such as PDU (Protocol Data Unit) session point to the outside, packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF and DN constitute a network slice. In the wireless communication network of this embodiment, multiple network slices are constructed.

[0013] AMF is connected to UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0014] The SMF is a network node 30 that has functions such as session management, IP (Internet Protocol) address allocation and management for UEs, DHCP (Dynamic Host Configuration Protocol) functionality, ARP (Address Resolution Protocol) proxy, and roaming functionality. The NEF is a network node 30 that has the function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 30 that has functions such as selecting the network slice to which the UE connects, determining the allowed NSSAI (Network Slice Selection Assistance Information), determining the NSSAI to be set, and determining the AMF set to which the UE connects. The PCF is a network node 30 that has the function of controlling network policies. The AF is a network node 30 that has the function of controlling application servers. The NRF is a network node 30 that has the function of discovering NF instances that provide services. The UDM is a network node 30 that manages subscriber data and authentication data. The UDM is connected to the UDR (User Data Repository) that holds the said data.

[0015] Figure 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Figure 2, the network consists of a terminal 20 (UE) and multiple network nodes 30. Hereafter, one network node 30 will be assigned to each function, but one network node 30 may implement multiple functions, or multiple network nodes 30 may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0016] The RAN is a network node 30 with wireless access functionality and is connected to the UE, AMF, and UPF. The AMF is a network node 30 with functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 interconnected with the DN, with functions such as external PDU session point, packet routing and forwarding, and user plane QoS handling. The UPF and DN constitute a network slice. In the wireless communication network of this embodiment, multiple network slices are constructed.

[0017] AMF is connected to UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0018] SMF is a network node 30 that has functions such as session management, IP address allocation and management for UEs, DHCP functionality, ARP proxy, and roaming functionality. NEF is a network node 30 that has the function of notifying other NFs of capabilities and events. NSSF is a network node 30 that has functions such as selecting the network slice to which the UE connects, determining which NSSAIs are allowed, determining which NSSAIs are configured, and determining which AMF set the UE connects to. PCF is a network node 30 that has the function of controlling network policies. AF is a network node 30 that has the function of controlling application servers. NRF is a network node 30 that has the function of discovering NF instances that provide services. SEPP is an opaque proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). In Figure 2, vSEPP is the SEPP in the visited network, and hSEPP is the SEPP in the home network.

[0019] As shown in Figure 2, the UE is in a roaming environment connected to the RAN and AMF in the Visited PLMN. The Visited PLMN and Home PLMN are connected via vSEPP and hSEPP. The UE can communicate with the UDM of the Home PLMN, for example, via the AMF of the Visited PLMN.

[0020] In an NG-RAN (Next Generation Radio Access Network), a gNB, which is a RAN node, may have an architecture separated into gNB-CUs (Central Units) and gNB-DUs (Distributed Units). One gNB-CU may accommodate multiple gNB-DUs, and one gNB-DU may accommodate multiple cells. F1AP (F1 Application Protocol) may be used for signaling between gNB-DUs and gNB-CUs.

[0021] 3GPP Release 19 (Rel.19) discusses the following Inter-MN LTM with / without SN change (Inter-CU MCG LTM with / without SN change):

[0022] - Inter-CU MCG LTM without SN release - Inter-CU MCG LTM with SN release - Inter-CU MCG LTM with SN addition

[0023] To support Inter-CU LTM (non-Dual Connectivity (DC) configuration) in Rel.19, XnAP messages and procedures for notifying the execution of cell switching, with similar functionality to F1AP, are being considered. Figure 3 shows an example of an Information Element (IE) included in an XnAP Cell Switch Notification message corresponding to Inter-CU LTM (non-DC configuration). This message is sent from the source NG-RAN node to the target NG-RAN node to notify the UE of the start of a cell switching command. The conventional XnAP Cell Switch Notification message shown in Figure 3 does not contain DC-related information.

[0024] For example, if both "MN change with SN release" and "MN change without SN change" are set as candidates for the same target cell (PCell), the target gNB may not be able to determine which mobility scenario (with / without SN change) was executed if the source gNB only notifies the target gNB of the target cell ID. This issue can occur if two or more of the following are set for the same target cell: Inter-CU MCG LTM with SN release, without SN release, and with SN addition.

[0025] In this situation, when a Distributed Unit (DU) makes a cell switch decision, it may not be able to select the optimal target cell from multiple pre-configured candidates based solely on information such as the Layer 1 Measurement Result (L1 MR) received by the DU. As a result, proper cell switching may not be performed.

[0026] According to this embodiment, in a mobility procedure (for example, cell switching), the MN that manages (controls) the target cell (Target PCell) can be notified whether the PCell switching involves a change in SN or whether it does not involve a change in SN.

[0027] In this embodiment, the cell switching notification messages for the Xn interface and the F1 interface may be configured to include information indicating whether the PCell switching involves a change in the SN or whether the PCell switching does not involve a change in the SN.

[0028] In this embodiment, information indicating whether the PCell switchover involves a change in SN or does not involve a change in SN may be represented, for example, as information indicating whether the T-MN managing the Target PCell is SN and DC or whether the T-MN managing the Target PCell is not DC.

[0029] The following describes the operation procedure of the communication system in this embodiment. Figure 4 is a sequence diagram showing an example of the operation procedure of the communication system in this embodiment.

[0030] The communication system of this embodiment includes a UE 20, a Source Master Node CU (S-MN CU) 10A-1, a Target MN CU (T-MN CU) 10B-1, and a Secondary Node CU (SN CU) 10C-1. The S-MN CU 10A-1 includes a DU 10A-2. The T-MN CU 10B-1 includes a DU 10B-2. The SN CN 10C-1 includes a DU 10C-2. The CUs and DUs may be included in a base station (gNB). In the CU and DU separation architecture, the CU is responsible for control plane processing, and the DU is mainly responsible for user plane processing.

[0031] In step S101, LTM preparation is performed. In this embodiment, during LTM preparation, new information may be set as candidate configuration for the switchover target, such as "information indicating that the T-MN managing the Target PCell is SN and DC (information indicating DC between T-MN and SN)" or "information indicating that the T-MN managing the Target PCell is not DC (information indicating non-DC with only T-MN)".

[0032] Information indicating that the T-MN managing the Target PCell is both an SN and a DC (information indicating a DC between the T-MN and the SN) or information indicating that the T-MN managing the Target PCell is not a DC (information indicating a non-DC with only a T-MN) may be specified as the candidate configuration ID.

[0033] In step S102, UE 20 transmits the L1 level measurement result (Layer 1 Measurement) to Source DU 10A-2.

[0034] In step S103, DU 10A-2 makes a decision (LTM decision) on whether or not to perform LTM based on the measurement results, etc.

[0035] In step S104, DU 10A-2 sends a Cell Switch Command to UE 20 as a trigger for LTM execution. This command includes the radio parameters and resource configurations necessary for UE 20 to properly reconnect to the specified target cell.

[0036] In step S105, DU 10A-2 sends an F1AP DU-CU Cell Switch Notification message to S-MN CU 10A-1 via the F1 interface. The F1AP DU-CU Cell Switch Notification message includes the Candidate configuration (e.g., candidate configuration ID) set in step S101. This allows DU 10A-2 to notify S-MN CU 10A-1 whether the T-MN managing the Target PCell is an SN and DC or not.

[0037] In step S106, S-MN CU 10A-1 sends an XnAP Cell Switch Notification message to T-MN CU 10B-1 via the Xn interface. The XnAP Cell Switch Notification message includes the Candidate configuration (e.g., candidate configuration ID) notified by DU 10A-2. This allows S-MN CU 10A-1 to notify T-MN CU 10B-1 whether the T-MN managing the Target PCell is an SN and DC or not a DC.

[0038] In step S107, T-MN CU 10B-1 sends an F1AP CU-DU Cell Switch Notification to its subordinate Target DU 10B-2 via the F1 interface.

[0039] In step S108, S-MN CU 10A-1 sends an XnAP Cell Switch Notification, XnAP LTM Configuration Update, or SN Modification Request message to SN CU 10C-1 via the Xn interface. These messages include the Candidate configuration (e.g., candidate configuration ID) notified by DU 10A-2. This allows S-MN CU 10A-1 to notify SN CU 10C-1 whether the T-MN managing the Target PCell is an SN and DC, or whether the T-MN managing the Target PCell is not a DC.

[0040] In step S109, SN CU 10C-1 sends an F1AP CU-DU Cell Switch Notification to its subordinate DU 10C-2 via the F1 interface.

[0041] In step S110, LTM is executed.

[0042] FIG. 5 is a diagram showing an example of an information element (IE (Information Element)) included in the F1AP CU-DU / DU-CU Cell Switch Notification message in the present embodiment. F1AP CU-DU / DU-CU Cell Switch Notification is a message specified in 3GPP TS38.473. As shown in FIG. 5, the F1AP CU-DU / DU-CU Cell Switch Notification message includes an LTM Configuration ID. The LTM Configuration ID may be included in an existing message such as UE Context Modification or a newly specified message.

[0043] FIG. 6 is a diagram showing an example of an information element (IE (Information Element)) included in the XnAP Cell Switch Notification message in the present embodiment. XnAP Cell Switch Notification is a message specified in 3GPP TS38.423. As shown in FIG. 6, the XnAP Cell Switch Notification message includes an LTM Configuration ID. The LTM Configuration ID may be included in an existing message such as UE Context Modification or a newly specified message.

[0044] In FIGS. 5 and 6, the name of the new IE is not limited to LTM Configuration ID, and may be any name.

[0045] As described above, according to the present embodiment, ambiguity or malfunction of processing on the target node side caused by execution of cell switching processing while it is unclear whether or not the change of SN is accompanied can be avoided.

[0046] According to the present embodiment, by adding information indicating whether or not the handover involves an SN change to a cell handover notification message on an Xn interface and an F1 interface, the target node can accurately grasp the handover type and execute an appropriate LTM process.

[0047] According to the present embodiment, even if the target cell is the same, it can be determined with high accuracy whether Inter-CU MCG LTM with SN release, without SN release, or with SN addition is being performed, so that unnecessary resource reservation and erroneous reconnection processing can be avoided.

[0048] According to the present embodiment, even in the LTM determination process in a DU, an optimal cell handover path can be selected by referring to information such as a preconfigured Candidate Configuration ID without depending only on a measurement result. As a result, the accuracy and reliability of mobility control for a UE can be improved, and it is possible to reduce deterioration of communication quality and disconnection risk during inter-cell handover.

[0049] According to the present embodiment, the present invention can be realized by adding an extended information element while maintaining compatibility with existing XnAP and F1AP protocol specifications, so that implementation in a form that maintains consistency with standard specifications is easy.

[0050] (Device Configuration) Next, an example of the functional configuration of a base station 10, a network node 30, and a terminal 20 that execute the processes and operations described so far will be described. The base station 10, the network node 30, and the terminal 20 include functions for implementing the above-described embodiments. However, each of the base station 10, the network node 30, and the terminal 20 may be provided with only some of the functions in the embodiments.

[0051] <Base Station and Network Node> Figure 7 shows an example of the functional configuration of a base station 10 and a network node 30. As shown in Figure 7, 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 Figure 7 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operation according to this embodiment. The network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having multiple different functions in the system architecture may be composed of multiple network nodes 30 separated by function.

[0052] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 or other network node 30 and transmitting the signal by wire or wireless. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 or other network node 30 and obtaining information from the received signal, for example, information from a higher layer. A communication unit including the transmitting unit 110 and the receiving unit 120 may be configured.

[0053] The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20 in a storage device, and reads it from the storage device as needed. The contents of the setting information include, for example, information related to continuous mobility.

[0054] The control unit 140 performs processing related to continuous mobility, as described in the embodiment. The control unit 140 also performs processing related to communication with the terminal 20. The signal transmission function of the control unit 140 may be included in the transmission unit 110, and the signal reception function of the control unit 140 may be included in the reception unit 120.

[0055] <Terminal> Figure 8 shows an example of the functional configuration of terminal 20. As shown in Figure 8, 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 Figure 8 is just one example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to this embodiment. In addition, the communication device that becomes the resource holder 20 may have a functional configuration similar to that of terminal 20.

[0056] The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit 220 wirelessly receives various signals and obtains signals from higher layers from the received physical layer signals. The receiving unit 220 also has the function of receiving NR-PSS, NR-SSS, NR-PBCH, DL / UL control signals or reference signals transmitted from the network node 30. A communication unit including the transmitting unit 210 and the receiving unit 220 may be configured.

[0057] The setting unit 230 stores various setting information received from the network node 30 by the receiving unit 220 in its storage device and reads it from the storage device as needed. The setting unit 230 also stores pre-configured setting information. The content of the setting information is, for example, information related to continuous mobility.

[0058] The control unit 240 performs processing related to continuous mobility, as described in the embodiment. The signal transmission function in the control unit 240 may be included in the transmission unit 210, and the signal reception function in the control unit 240 may be included in the reception unit 220.

[0059] (Hardware Configuration) The block diagrams (Figures 7 and 8) used in the description of the above embodiments show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may be realized by combining the one device or the multiple devices with software.

[0060] Functions include, but are not limited to, judgment, decision, determination, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In all cases, as mentioned above, the method of implementation is not particularly limited.

[0061] For example, the network node 30, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 9 is a diagram showing an example of the hardware configuration of a base station 10 and terminal 20 according to one embodiment of the present disclosure. The network node 30 may have the same hardware configuration as the base station 10. The above-mentioned base station 10 and terminal 20 may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0062] In the following explanation, the term "device" can be read as "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices.

[0063] Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and storage device 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of data reading and writing in the storage device 1002 and auxiliary storage device 1003.

[0064] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001.

[0065] Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10 shown in Figure 7 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Also, for example, the control unit 240 of the terminal 20 shown in Figure 8 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above-described processes have been explained as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from the network via a telecommunications line.

[0066] The storage device 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of the present disclosure.

[0067] The auxiliary storage device 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc 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 multipurpose disk, a Blu-ray® disk), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The above-mentioned storage medium may also be a database, server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

[0068] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may be configured to include, for example, a high-frequency switch, duplexer, filter, frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting and receiving antenna, amplifier section, transmitting and receiving section, transmission path interface, etc., may be implemented by the communication device 1004. The transmitting and receiving section may be implemented in a physically or logically separated manner, with a transmitting section and a receiving section.

[0069] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0070] Furthermore, each device, such as the processor 1001 and the storage device 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0071] Furthermore, the base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0072] Figure 10 shows an example of the configuration of vehicle 2001. As shown in Figure 10, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in this disclosure may be applied to a communication device mounted on vehicle 2001, for example, to the communication module 2013.

[0073] The drive unit 2002 consists of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel, which is operated by the user.

[0074] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2029 installed in the vehicle 2001 are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0075] Signals from various sensors 2021 to 2029 include current signals from current sensor 2021 for sensing motor current, front and rear wheel rotation speed signals acquired by rotation speed sensor 2022, front and rear wheel air pressure signals acquired by air pressure sensor 2023, vehicle speed signals acquired by vehicle speed sensor 2024, acceleration signals acquired by acceleration sensor 2025, accelerator pedal depression signals acquired by accelerator pedal sensor 2029, brake pedal depression signals acquired by brake pedal sensor 2026, shift lever operation signals acquired by shift lever sensor 2027, and detection signals acquired by object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0076] The Information Service Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Service Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001. The Information Service Unit 2012 may include input devices that accept input from the outside (e.g., keyboard, mouse, microphone, switch, button, sensor, touch panel, etc.) and output devices that perform output to the outside (e.g., display, speaker, LED lamp, touch panel, etc.).

[0077] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0078] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-29 provided in the vehicle 2001.

[0079] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information with external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0080] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include the information based on the above input.

[0081] The communication module 2013 receives various information (traffic information, signal information, inter-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from the external device in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021-2029, etc., provided in the vehicle 2001.

[0082] <Notes> (Note 1) A base station comprising: a control unit that makes a decision on whether or not to perform mobility; and a transmission unit that transmits information to a target base station that manages the target cell in the mobility, indicating whether or not the switch to the target cell involves a change in the secondary node. (Note 2) The base station according to Note 1, wherein the information indicates whether or not the target base station constitutes dual connectivity with the secondary node. (Note 3) The base station according to Note 1, wherein in the preparation procedure for the mobility, it is determined whether or not the switch to the target cell involves a change in the secondary node. (Note 4) The base station according to Note 1, wherein the base station has a CU (Central Unit) and a DU (Distributed Unit), and information indicating whether or not the switch to the target cell involves a change in the secondary node is transmitted from the DU to the CU. (Appendix 5) The base station described in Appendix 1, wherein the mobility is LTM (Lower layer Triggered Mobility). (Appendix 6) A communication method performed by a base station, comprising the steps of: deciding whether or not to perform mobility; and transmitting information to a target base station managing the target cell in the mobility indicating whether or not the switch to the target cell involves a change in the secondary node.

[0083] The above configuration enables the execution of appropriate mobility, taking into account whether or not there have been changes to the secondary cell.

[0084] (Supplement to Embodiments) Although these embodiments have been described above, the disclosed invention is not limited to these embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but 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, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. The processing procedures described in the embodiments may be rearranged as long as they do not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized in 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 be stored in any suitable storage medium such as random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or other appropriate storage medium.

[0085] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or combinations thereof. Also, RRC signaling may be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0086] Each aspect / embodiment described in this disclosure refers to LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (where x is, for example, an integer or decimal)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20 may apply to at least one system utilizing UWB (Ultra-WideBand), Bluetooth®, or other appropriate systems, and to next-generation systems extended, modified, created, or defined based thereon. Alternatively, multiple systems may be applied in combination (e.g., a combination of at least one of LTE and LTE-A with 5G).

[0087] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0088] In this specification, specific operations performed by the base station 10 may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with the terminal 20 can be performed by the base station 10 and at least one of the other network nodes (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station 10, the other network node may be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0089] The information or signals described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes.

[0090] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be transmitted to other devices.

[0091] The determination in this disclosure may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0092] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0093] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0094] The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0095] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0096] The terms “system” and “network” as used in this disclosure are interchangeable.

[0097] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0098] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0099] In this disclosure, terms such as "Base Station (BS)", "wireless base station", "base station equipment", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0100] A base station can accommodate one or more (e.g., three) cells. If a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a Remote Radio Head (RRH)). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage.

[0101] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0102] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0103] A mobile station may also be referred to by those skilled in the art 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, or several other appropriate terms.

[0104] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station may include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0105] Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.). In this case, the terminals 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc., may be interpreted as side channel.

[0106] Similarly, the term "user terminal" in this disclosure may be replaced with "base station." In this case, the base station may be configured to have the same functions as the user terminal described above.

[0107] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0108] The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0109] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0110] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0111] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0112] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0113] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0114] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0115] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0116] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0117] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way.

[0118] This international patent application claims priority based on Japanese Patent Application No. 2025-056056, filed on 28 March 2025, and the entire contents of Japanese Patent Application No. 2025-056056 are incorporated herein by reference.

[0119] 10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 30 Network node 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device

Claims

1. A base station comprising: a control unit that makes a decision on whether or not to perform mobility; and a transmission unit that transmits information to a target base station that manages the target cell in the mobility, indicating whether or not the switch to the target cell involves a change in the secondary node.

2. The base station according to claim 1, wherein the information indicates whether the target base station constitutes dual connectivity with the secondary node or not.

3. The base station according to claim 1, wherein in the mobility preparation procedure, it is determined whether the switch to the target cell involves a change in the secondary node or not.

4. The base station according to claim 1, wherein the base station has a CU (Central Unit) and a DU (Distributed Unit), and information indicating whether the switch to the target cell involves a change in the secondary node or not is transmitted from the DU to the CU.

5. The base station according to claim 1, wherein the mobility is LTM (Lower layer triggered mobility).

6. A communication method performed by a base station, comprising the steps of: deciding whether or not to perform mobility; and transmitting information to a target base station that manages the target cell in the mobility, indicating whether or not the switch to the target cell involves a change in the secondary node.

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