Base station and communication method

Abstract

To allow security-related information to be communicated from a switching source (source side) to a switching destination (target side) even if the preparation phase of a mobility procedure is not performed.SOLUTION: A base station includes a control unit that determines whether to perform mobility, and a transmitting unit that transmits security-related information relating to a terminal that is a target of mobility to a target base station after the preparation procedure of the mobility.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] In 3GPP (3rd Generation Partnership Project) (registered trademark), support for subsequent mobility in LTM (Lower layer Triggered Mobility) or conditional handover is being considered as an extension of mobility (e.g., cell switching) functions.

[0003] Conventionally, in procedures involving cell switching, security-related information was notified from the source gNB to the target gNB during the preparation phase. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TSG-RAN Meeting #101 RP-232618, Bengaluru, India, 11-15 September 2023 [Non-patent document 2] 3GPP TS 33.501 V19.2.0 (2025-03) Summary of the Invention [Problem to be solved by the invention]

[0005] However, in continuous mobility, the preparation stage may not be performed, which may result in the Source gNB not being able to notify the Target gNB of security-related information. [Means for solving the problem]

[0006] The base station in this embodiment comprises a control unit that decides whether to perform mobility, and a transmission unit that transmits security-related information regarding the terminal that is the target of mobility to the target base station after the mobility preparation procedure. [Effects of the Invention]

[0007] According to this embodiment, even if the preparation phase of the mobility procedure is not executed, security-related information can be notified from the switching source (source side) to the switching destination (target side). [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a communication system. [Figure 2] FIG. 1 is a diagram illustrating an example of a communication system in a roaming environment. [Figure 3] 10] FIG. 10 is a diagram showing an example of information elements included in an Xn Cell Switch Notification message in this embodiment. [Figure 4] FIG. 10 is a diagram showing an example of information elements included in an F1 CU-DU Cell Switch Notification message in this embodiment. [Figure 5] 10 is a diagram showing an example of information elements included in an F1AP AS Security Information message in this embodiment. FIG. [Figure 6] FIG. 10 is a sequence diagram showing an example of an operation procedure including notification of security-related information in the present embodiment. [Figure 7] FIG. 10 is a sequence diagram showing an example of an operation procedure including notification of security-related information in the present embodiment. [Figure 8] FIG. 2 is a diagram illustrating an example of the functional configuration of a base station and a network node according to the present embodiment. [Figure 9] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal according to the present embodiment. [Figure 10] FIG. 2 is a diagram illustrating an example of the hardware configuration of a base station and a terminal according to the present embodiment. [Figure 11] 1 is a diagram illustrating an example of a configuration of a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] The communication system of this embodiment operates using existing technology. The existing technology is, for example, a wireless communication technology based on a communication standard such as the 3GPP standard. The existing technology is, for example, NR (New Radio), but is not limited to existing NR. Unless otherwise specified, the term "NR" used in this specification has a broad meaning including NR (5G) and subsequent systems (for example, 6G).

[0011] In this embodiment, when radio parameters etc. are "configured," it may mean that a predetermined value is pre-configured, or that radio parameters notified from the network node 30 or the terminal 20 are set.

[0012] Fig. 1 is a diagram illustrating an example of a communication system. As shown in Fig. 1, the communication system is composed of a UE, which is a terminal 20, and multiple network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0013] The RAN (Radio Access Network) is a network node 30 having a radio access function, which may include a base station 10, and is connected to a UE, an AMF (Access and Mobility Management Function), and a UPF (User plane function). The AMF is a network node 30 having functions such as terminating the RAN interface, terminating the NAS (Non-Access Stratum), registering management, connecting management, reachability management, and mobility management. The UPF is a network node 30 having functions such as a PDU (Protocol Data Unit) session point to the outside that interconnects with a DN (Data Network), routing and forwarding of packets, and user plane QoS (Quality of Service) handling. The UPF and the DN constitute a network slice. In the wireless communication network of this embodiment, multiple network slices are constructed.

[0014] The AMF is connected to the 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). The 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.

[0015] The SMF is a network node 30 that has functions such as session management, UE IP (Internet Protocol) address allocation and management, DHCP (Dynamic Host Configuration Protocol) function, ARP (Address Resolution Protocol) proxy, and roaming function. The NEF is a network node 30 that has a function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 30 that has functions such as selecting a network slice to which a UE connects, determining allowed NSSAIs (Network Slice Selection Assistance Information), determining the NSSAI to be configured, and determining the AMF set to which the UE connects. The PCF is a network node 30 that has a function of controlling network policies. The AF is a network node 30 that has a function of controlling application servers. The NRF is a network node 30 that has a 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 a UDR (User Data Repository) that stores the data.

[0016] Fig. 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Fig. 2, the network is composed of a UE, which is a terminal 20, and multiple network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0017] The RAN is a network node 30 having a radio access function, and is connected to the UE, the AMF, and the UPF. The AMF is a network node 30 having functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 having functions such as a PDU session point to the outside that interconnects with the DN, packet routing and forwarding, and user plane QoS handling. The UPF and the DN constitute a network slice. In the wireless communication network of this embodiment, multiple network slices are constructed.

[0018] The AMF is connected to the UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via their respective service-based interfaces, Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0019] The SMF is a network node 30 having functions such as session management, UE IP address allocation and management, DHCP function, ARP proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which a UE connects, determining an allowed NSSAI, determining an NSSAI to be configured, and determining an AMF set to which a UE connects. The PCF is a network node 30 having a function of controlling network policies. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The SEPP is a non-transparent proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). The vSEPP shown in Figure 2 is the SEPP in the visited network, and the hSEPP is the SEPP in the home network.

[0020] As shown in Figure 2, a UE is in a roaming environment connected to a RAN and an AMF in a Visited PLMN (VPLMN). The VPLMN and a Home PLMN (HPLMN) are connected via a vSEPP and an hSEPP. The UE can communicate with a UDM in the HPLMN via the AMF in the VPLMN, for example.

[0021] In NG-RAN (Next Generation Radio Access Network), the gNB, which is a RAN node, may have an architecture separated into a gNB-CU (Central Unit) and a gNB-DU (Distributed Unit). 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 the gNB-DU and gNB-CU.

[0022] 3GPP is considering supporting continuous mobility in LTM or conditional handover as an extension of mobility (e.g., cell switching) functionality. LTM is a procedure in which mobility (e.g., cell switching) is performed based on measurement results or event triggers in a layer (Layer 1 or Layer 2) below the RRC layer. In LTM, mobility is indicated by the network at the MAC CE.

[0023] Conventionally, in a mobility procedure, security-related information is communicated from the Source CU to the Target CU in the preparation phase.

[0024] However, in a successive mobility procedure, it is possible that the preparation phase is not performed, and therefore security-related information may not be communicated from the Source CU to the Target CU.

[0025] According to this embodiment, it is possible to notify security-related information from a source CU to a target CU, not only during the preparation stage of a mobility procedure. A method for notifying security-related information in this embodiment will be described below.

[0026] In this embodiment, the security-related information may be included in a message sent from the Source CU to the Target CU or other candidate CUs to notify the execution of mobility. The message to notify the execution of mobility may be at least one of an Xn message or an F1 message.

[0027] The Xn message notifying the execution of mobility may be an Xn Cell Switch Notification message and an Xn LTM Configuration Update message in inter-CU LTM.

[0028] The F1 message notifying the mobility execution may be an F1 Cell Switch Notification message and an F1 UE Context Modification message.

[0029] The security-related information in this embodiment may be AS (Access Stratum) security information, which may be AS Security Information defined in the 3GPP standard (for example, 3GPP TS38.423 section 9.2.3.49).

[0030] The security-related information in this embodiment may include at least one of K_gNB, K_gNB*, NCC (Next hop Chaining Counter), or NH (Next Hop) parameters.

[0031] The security-related information in this embodiment may include a list of NCC values ​​pre-configured in the UE. The security-related information may include the list of NCC values ​​in addition to AS security information.

[0032] K_gNB is a session key for encryption and integrity protection used between the UE and the gNB (including the CU / DU). The derivation of K_gNB may be, for example, horizontal key derivation, vertical key derivation, or derivation based on the NAS security context, based on existing 3GPP specifications.

[0033] K_gNB* is a gNB key to be used at the next gNB (Target gNB). K_gNB* may be derived from, for example, the NH parameters.

[0034] The NH parameter is an intermediate value for generating a future gNB key (K_gNB*). The NH parameter is derived, for example, during re-authentication or key update between the UE and the AMF.

[0035] NCC is a counter that indicates the number of times the NH parameters have been updated.

[0036] FIG. 3 is a diagram showing an example of information elements (IEs) included in the Xn Cell Switch Notification message in this embodiment. As shown in FIG. 3, the Xn Cell Switch Notification message includes AS Security Information and / or an NCC Value List as new IEs indicating security-related information. The NCC value list includes, for example, an NCC value item. The NCC value item includes a Next Hop Chaining Count (NCC). The new IE indicating security-related information (e.g., AS Security Information) may be included in an LTM Configuration Update message, an LTM Configuration Update Acknowledge message, another existing message, or a newly defined message.

[0037] 4 is a diagram showing an example of IEs included in the F1 CU-DU Cell Switch Notification message in this embodiment. As shown in FIG. 4, the F1 CU-DU Cell Switch Notification message includes Cell ID and AS Security Information as new IEs indicating security-related information. The F1 CU-DU Cell Switch Notification message may also include an AS Security Information List. The AS Security Information List includes a Cell ID, an LTM Configuration ID, and AS Security Information. When the F1 CU-DU Cell Switch Notification message includes the AS Security Information List, the Cell ID and AS Security Information do not necessarily need to be included as IE items. The new IE indicating security-related information (e.g., AS Security Information) may be included in the DU-CU Cell Switch Notification message, the UE Context Modification Request message, another existing message, or a newly defined message.

[0038] 5 is a diagram showing an example of IEs included in the F1AP AS Security Information message in this embodiment. As shown in FIG. 5, the F1 CU-DU Cell Switch Notification message includes Key NG-RAN Star and Next Hop Chaining Count as new IEs indicating security-related information.

[0039] In FIG. 3-5, the name of the new IE indicating the security-related information or the content indicated by the IE may be arbitrary.

[0040] Next, a procedure for notifying security-related information in this embodiment will be described. The procedures shown in Figures 6 and 7 below may be performed independently, or at least some of the procedures may be combined and performed.

[0041] FIG. 6 is a sequence diagram showing an example of a procedure in which security-related information is notified by a cell switch notification after an LTM decision in this embodiment.

[0042] The communication system of this embodiment includes a UE 20, a Source gNB (a base station from which to switch) 10A, a Target gNB (a base station to which to switch) 10B, and an Other candidate gNB (another candidate base station to switch) 10C. Each gNB is composed of a Central Unit (CU) and a Distributed Unit (DU), and for example, the Source gNB 10A includes a Source CU 101A and a DU 102A. In the CU and DU separated architecture, the CU is responsible for control plane processing, and the DU is mainly responsible for user plane processing.

[0043] In step S101, LTM preparation or previous cell switch is performed.

[0044] In step S102, new security-related information is generated. The Source CU 101A may generate security-related information for the next cell switch. The generation of the security-related information may be performed after the previous cell switch is completed (i.e., after receiving a handover success message) or after receiving a cell switch notification for the previous cell switch.

[0045] In step S103, the Source CU 101A sends an F1AP UE Context Modification message to the Source DU 102A via the F1 interface, which may include the generated security-related information.

[0046] In step S104, the UE 20 transmits the measurement result at the L1 level (Layer 1 Measurement) to the Source DU 102A.

[0047] In step S105, the DU 102A makes a decision (LTM decision) as to whether or not to execute LTM based on the measurement result and the like.

[0048] In step S106, the DU 102A sends a Cell Switch Command to the UE 20 as a trigger for executing the LTM. This command may include radio parameters and resource configurations required for the UE to properly reconnect to the specified target cell, as well as security-related information obtained from the Source CU 101A in step S103.

[0049] In step S107, the DU 102A transmits an F1AP DU-CU Cell Switch Notification to the Source CU 101A via the F1 interface. This notification includes the security-related information notified to the UE 20 in step S106.

[0050] In step S108, the Source CU 101A sends an XnAP Cell Switch Notification or LTM Configuration Update message to the Target CU 101B via the Xn interface. The XnAP Cell Switch Notification or LTM Configuration Update message includes the security-related information notified by the Cell Switch Notification in step S107. This security-related information includes the content of the security-related information notified to the UE 20 in step S106, so that the target CU can properly prepare the security information to be used in the subsequent LTM procedure.

[0051] In step S109, the Target CU 101B transmits an F1AP CU-DU Cell Switch Notification to the Target DU 102B via the F1 interface.

[0052] In steps S110 and S111, the Source CU 101A sends an XnAP Cell Switch Notification or an LTM Configuration Update to another candidate CU (CU 101C), and the other candidate CU 101C sends a CU-DU Cell Switch Notification to the DU 102C. These notifications may also include security-related information.

[0053] Either or both of steps S108-S109 and steps S110-S111 may be performed in parallel.

[0054] In step S112, LTM is executed using the security-related information notified to the Target side (LTM execution with security refresh). That is, a new AS security context between the UE 20 and the Target CU 101B is established using a key such as K_gNB* provided by the Source CU 101A.

[0055] FIG. 7 is a sequence diagram showing an example of a procedure in which security-related information is notified by an LTM Configuration Update or a UE Context Modification before an LTM decision is made in this embodiment.

[0056] In step S201, LTM preparation or previous cell switch is performed.

[0057] In step S202, new security-related information is generated. Source CU 101A may generate security-related information for the next cell switch. The generation of security-related information may be performed after the previous cell switch is completed (i.e., after receiving a handover success message) or after receiving a cell switch notification for the previous cell switch.

[0058] In step S203, the Source CU 101A sends an F1AP UE Context Modification message to the Source DU 102A via the F1 interface, which may include the generated security-related information.

[0059] In step S204, the Source CU 101A sends an XnAP LTM Configuration Update message to the Target CU 101B via the Xn interface. This message may include the generated security-related information.

[0060] In step S205, the Source CU 101A transmits an XnAP LTM Configuration Update message to another candidate CU (Other candidate CU 101C). This message may include the generated security-related information.

[0061] Either or both of the above steps S204 and S205 may be executed in parallel.

[0062] In step S206, the UE 20 transmits the measurement result at the L1 level (Layer 1 Measurement) to the Source DU 102A.

[0063] In step S207, the DU 102A makes a decision (LTM decision) as to whether or not to execute LTM based on the received measurement result and the like.

[0064] In step S208, the DU 102A transmits a Cell Switch Command to the UE 20. As a result, the UE 20 starts a reconnection process to the specified Target Cell.

[0065] In step S209, the DU 102A sends an F1AP DU-CU Cell Switch Notification message to the Source CU 101A. This message may include security-related information.

[0066] In step S210, the Source CU 101A transmits an XnAP LTM Configuration Update to the Target CU 101B, which causes the Target CU 101B to check the security information and complete preparations for reception.

[0067] In step S211, the Target CU 101B transmits an F1AP CU-DU Cell Switch Notification to the Target DU 102B via the F1 interface.

[0068] In step S212, the Source CU 101A transmits an XnAP Cell Switch Notification or an LTM Configuration Update message to the Other candidate CU 102C via the Xn interface.

[0069] In step S213, the Other candidate CU 102C transmits an F1AP CU-DU Cell Switch Notification or a UE Context Modification to the Other candidate DU 102C via the F1 interface.

[0070] In step S214, LTM Execution with Security Refresh is performed using the security-related information notified by the above procedure. That is, after AS security based on a new key such as K_gNB* is established, mobility processing of the UE 20 is executed.

[0071] According to the above-described embodiment, even if the preparation phase of the mobility procedure is not executed, security-related information can be reliably notified from the source CU (switching source) to the target CU (switching destination). As a result, even in situations where rapid cell switching is required, such as sequential mobility or LTM, the target base station can prepare AS security information, and mobility can be efficiently realized while maintaining secure connectivity between the UE and the network.

[0072] Furthermore, according to this embodiment, security-related information is notified via the Xn or F1 interface by being included in an LTM Configuration Update message or a Cell Switch Notification message, thereby improving implementation flexibility and reliability while maintaining consistency with existing 3GPP interface specifications.

[0073] (Device configuration) Next, a description will be given of examples of functional configurations of the base station 10, network node 30, and terminal 20 that perform the processes and operations described above. The base station 10, network node 30, and terminal 20 include functions for performing the above-described embodiments. However, the base station 10, network node 30, and terminal 20 may each include only a part of the functions of the embodiments.

[0074] <Base stations and network nodes> FIG. 8 is a diagram showing an example of the functional configuration of the base station 10 and the network node 30. As shown in FIG. 8, 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. 8 is merely an example. As long as the operation according to this embodiment can be performed, the names of the functional divisions and functional units may be any. Note that 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.

[0075] The transmitter 110 includes a function of generating a signal to be transmitted to the terminal 20 or another network node 30, and transmitting the signal by wire or wirelessly. The receiver 120 includes a function of receiving various signals transmitted from the terminal 20 or another network node 30, and acquiring, for example, information of a higher layer from the received signal. A communication unit including the transmitter 110 and the receiver 120 may be configured.

[0076] The setting unit 130 stores in a storage device setting information that is set in advance and various setting information to be transmitted to the terminal 20, and reads out the setting information from the storage device as needed. The setting information includes, for example, information related to continuous mobility.

[0077] 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 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.

[0078] <terminal> FIG. 9 is a diagram showing an example of the functional configuration of the terminal 20. As shown in FIG. 9, 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. 9 is merely an example. As long as the operation according to this embodiment can be performed, the names of the functional divisions and functional units may be any. Furthermore, the communication device that becomes the resource holder 20 may have the same functional configuration as the terminal 20.

[0079] The transmitter 210 creates a transmission signal from transmission data and transmits the transmission signal wirelessly. The receiver 220 receives various signals wirelessly and acquires higher layer signals from the received physical layer signals. The receiver 220 also has a function of receiving NR-PSS, NR-SSS, NR-PBCH, DL / UL control signals, reference signals, and the like transmitted from the network node 30. A communication unit including the transmitter 210 and the receiver 220 may be configured.

[0080] The setting unit 230 stores various setting information received from the network node 30 by the receiving unit 220 in a storage device and reads it from the storage device as needed. The setting unit 230 also stores setting information that is set in advance. The content of the setting information is, for example, information related to continuous mobility.

[0081] The control unit 240 performs processing related to continuous mobility as described in the embodiment. The function unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and the function unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0082] (Hardware configuration) The block diagrams (FIGS. 8 and 9) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or the multiple devices with software.

[0083] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocation, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how these functions are implemented.

[0084] For example, the network node 30, the terminal 20, 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. 10 is a diagram illustrating an example of the hardware configuration of the base station 10 and the terminal 20 according to an embodiment of the present disclosure. The network node 30 may have the same hardware configuration as the base station 10. The above-described base station 10 and the 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.

[0085] In the following description, the term "apparatus" can be read as a circuit, a device, a unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0086] 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, the memory device 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls at least one of reading and writing data in the memory device 1002 and the auxiliary memory device 1003.

[0087] The processor 1001 controls the entire computer by running, for example, an operating system. 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, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0088] Furthermore, the processor 1001 reads programs (program codes), software modules, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 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 140 of the base station 10 shown in FIG. 8 may be implemented by a control program stored in the storage device 1002 and executed by the processor 1001. Furthermore, for example, the control unit 240 of the terminal 20 shown in FIG. 9 may be implemented by a control program stored in the storage device 1002 and executed by the processor 1001. While the above-described various processes have been described as being executed by one 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.

[0089] The storage device 1002 is a computer-readable recording medium and may be configured, for example, by at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The storage device 1002 may also be called a register, a cache, a main memory, etc. The storage device 1002 can store executable programs (program codes), software modules, etc. for implementing a communication method according to an embodiment of the present disclosure.

[0090] The secondary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of 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, etc. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium including at least one of the storage device 1002 and the secondary storage device 1003.

[0091] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, 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, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, a transmission / reception antenna, an amplifier unit, a transmission / reception unit, a transmission path interface, etc. may be realized by the communication device 1004. The transmission / reception unit may be implemented as a transmission unit and a reception unit that are physically or logically separated.

[0092] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that performs output to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0093] 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 may be configured using different buses between each device.

[0094] 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), or a field programmable gate array (FPGA), 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.

[0095] Fig. 11 shows an example configuration of a vehicle 2001. As shown in Fig. 11, the 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 the present disclosure may be applied to a communication device mounted on the vehicle 2001, and may be applied to the communication module 2013, for example.

[0096] The drive unit 2002 is configured, for example, by 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 operated by the user.

[0097] The electronic control unit 2010 is composed of a microprocessor 2031, a memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0098] The signals from the various sensors 2021 to 2029 include a current signal from a current sensor 2021 that senses the current of the motor, a rotation speed signal of the front and rear wheels obtained by a rotation speed sensor 2022, an air pressure signal of the front and rear wheels obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

[0099] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from external devices via the communication module 2013 or the like to provide various types of multimedia information and multimedia services to the occupants of the vehicle 2001. The information service unit 2012 may include input devices (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, a touch panel, etc.) that accept input from the outside, and may also include output devices (e.g., a display, a speaker, an LED lamp, a touch panel, etc.) that output information to the outside.

[0100] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driver's driving burden, such as a millimeter-wave radar, a LiDAR (Light Detection and Ranging), a camera, a positioning locator (e.g., GNSS, etc.), map information (e.g., high-definition (HD) map, autonomous vehicle (AV) map, etc.), a gyro system (e.g., an IMU (Inertial Measurement Unit), an INS (Inertial Navigation System), etc.), an AI (Artificial Intelligence) chip, and an AI processor, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize the driving assistance function or the autonomous driving function.

[0101] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 29, which are provided in the vehicle 2001.

[0102] 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 an external device. For example, it transmits and receives various information to and from the external device 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, a mobile station, or the like.

[0103] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0104] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker 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 external devices 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 to 2029, etc. provided in the vehicle 2001.

[0105] <Additional Notes> (Additional note 1) a control unit that makes a decision (e.g., an LTM decision) as to whether to perform mobility (e.g., LTM); A base station (e.g., Source gNB 10A / CU 101A) comprising: a transmitter that transmits security-related information regarding a terminal that is a mobility target to a target base station (e.g., Target gNB 10B / CU 101B) after the mobility preparation procedure (e.g., LTM preparation).

[0106] (Additional note 2) The control unit generates the security-related information before the determination, The base station according to claim 1, wherein the transmitter transmits the generated security-related information to the target base station before the determination.

[0107] (Additional note 3) The base station according to Supplementary claim 2, wherein the control unit generates the security-related information before the determination, after completion of a previous cell switch, or after receiving a cell switch notification related to the previous cell switch.

[0108] (Additional note 4) The base station has a Central Unit (CU) and a Distributed Unit (DU), The base station according to claim 1, wherein the security-related information is included in a cell switching notification sent from the DU to the CU after the determination.

[0109] (Additional note 5) The base station according to Supplementary Item 1, wherein the mobility is Lower Layer Triggered Mobility (LTM).

[0110] (Additional note 6) 1. A communication method performed by a base station, comprising: making a decision whether to perform mobility; After the mobility preparation procedure, transmitting security-related information related to the terminal that is the mobility target to a target base station.

[0111] With the above configuration, even if the preparation phase of the mobility procedure is not executed, security-related information can be reliably notified from the Source CU (gNB) to the Target CU (gNB). This enables the target base station to prepare AS security information even in situations where rapid cell switching is required, such as sequential mobility and LTM, and enables efficient mobility while maintaining secure connectivity between the UE and the network. (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.

[0112] Furthermore, 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), 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), System Information Block (SIB)), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0113] Each aspect / embodiment described in the present disclosure may be any of the following: LTE (Long Term Evolution), LTE-Advanced (LTE-A), 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 (x is, for example, an integer or decimal number)), 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 The present invention may be applied to at least one of systems using 802.20, UWB (Ultra-Wideband), Bluetooth (registered trademark), or other appropriate systems, and next-generation systems that are extended, modified, created, or defined based on these systems. The present invention may also be applied to a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G).

[0114] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described herein 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.

[0115] In this specification, a specific operation that is described as being performed by the base station 10 may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station 10, it is clear that various operations performed for communication with the terminal 20 may be performed by at least one of the base station 10 and another network node other than the base station 10 (such as, but not limited to, an MME or an S-GW). Although the above example illustrates a case where there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (such as an MME and an S-GW).

[0116] The information or signals described in the present disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0117] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0118] In the present disclosure, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0119] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0120] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0121] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0122] Note that terms explained 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 a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0123] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0124] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by an index.

[0125] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0126] In the present disclosure, terms such as "base station (BS)," "radio base station," "base station device," "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.

[0127] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication service by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or base station subsystem that provides communication service within this coverage.

[0128] In the present disclosure, the base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

[0129] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0130] 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 some other suitable terminology.

[0131] At least one of the base station and the mobile station may be referred to as a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, the mobile object itself, etc. The mobile object refers to a movable object, and may move at any speed. Naturally, this also includes cases where the mobile object is stationary. Examples of the mobile object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The mobile object may also be a mobile object that moves autonomously based on an operational command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does 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.

[0132] Furthermore, a base station in the present disclosure may be read as a user 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 user terminal is replaced with communication between a plurality of terminals 20 (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0133] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station may be configured to have the functions of the user terminal described above.

[0134] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0135] The terms "connected," "coupled," or any variation thereof, refer to 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" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0136] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0137] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0138] 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.

[0139] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0140] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0141] 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.

[0142] In the present 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 "coupled" may also be interpreted in the same way as "different."

[0143] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, notification of predetermined information (e.g., notification that "X is true") is not limited to being done explicitly, but may be done implicitly (e.g., by not notifying the predetermined information).

[0144] Although the present disclosure has been described in detail above, it is 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 spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure. [Explanation of symbols]

[0145] 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 30 network nodes 1001 processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication equipment 1005 Input Device 1006 Output Device

Claims

1. a control unit that determines whether to perform mobility; a transmitter that transmits security-related information related to the terminal that is a mobility target to a target base station after the mobility preparation procedure.

2. The control unit generates the security-related information before the determination, The base station according to claim 1 , wherein the transmitter transmits the generated security-related information to the target base station before the determination.

3. The base station according to claim 2 , wherein the control unit generates the security-related information before the determination, after completion of a previous cell switch, or after receiving a cell switch notification related to the previous cell switch.

4. The base station has a Central Unit (CU) and a Distributed Unit (DU), The base station according to claim 1 , wherein the security-related information is included in a cell switch notification sent from the DU to the CU after the determination.

5. The base station according to claim 1 , wherein the mobility is Lower Layer Triggered Mobility (LTM).

6. 1. A communication method performed by a base station, comprising: making a decision whether to perform mobility; After the mobility preparation procedure, transmitting security-related information related to the terminal that is the mobility target to a target base station.

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