Terminal, base station, wireless communication system, and wireless communication method

Abstract

This terminal comprises: a communication unit that communicates with a base station which forms a candidate cell of a movement destination for the terminal; and a control unit that generates a security key for the candidate cell on the basis of a key generation parameter for each candidate cell. The communication unit transmits key-related information relating to the key generation parameter.

Description

Terminal, base station, wireless communication system, and wireless communication method

[0001] The present disclosure relates to a terminal, a base station, a wireless communication system, and a wireless communication method that support subsequent CPC.

[0002] The 3rd Generation Partnership Project (3GPP) has developed specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation, known as Beyond 5G, 5G Evolution, or 6G.

[0003] 3GPP Release 18 is considering methods for suppressing an increase in signaling overhead caused by repeated resetting and discarding of configuration information between a terminal and a network when the terminal moves between specific candidate cells (see, for example, Non-Patent Document 1). Configuration information is information used for communication between a terminal and base stations that form multiple candidate cells. Examples of configuration information include UE context and conditional config.

[0004] “Revised WID on Further NR mobility enhancements”, RP-221799, 3GPP TSG RAN Meeting #96, Budapest, Hungary, June 6-9, 2022

[0005] Incidentally, a method (Subsequent CPC) has been proposed in which the terminal continues to hold the configuration information even after the terminal has completed moving to the base station that forms the candidate cell, thereby preventing the reconfiguration and discarding of the configuration information. In such a method, from the viewpoint of security, a security key (e.g., K SN In this case, it is necessary to update a key generation parameter (for example, an sk counter value or an NCC (Next Hop Chaining Counter) parameter) used by the terminal to generate the .

[0006] Under such circumstances, the inventors have conducted extensive research and found that it is necessary to appropriately allocate the number of security keys for candidate cells, assuming that security keys for candidate cells will be exhausted.

[0007] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a terminal, a base station, a wireless communication system, and a wireless communication method that can appropriately suppress the depletion of security keys for candidate cells.

[0008] An aspect of the disclosure is a terminal comprising: a communication unit that communicates with a base station that forms a candidate cell to which the terminal is to move; and a control unit that generates a security key for the candidate cell based on a key generation parameter for each of the candidate cells, wherein the communication unit transmits predicted information regarding the number of security keys to be allocated to the candidate cell.

[0009] The disclosed aspect is a base station comprising: a communication unit that communicates with a terminal; and a control unit that assumes that the terminal will generate a security key for the candidate cell based on key generation parameters for each candidate cell to which the terminal will move, wherein the control unit predicts the number of security keys to be allocated to the candidate cell based on a predicted trajectory of the cell to which the terminal will move.

[0010] An aspect of the disclosure is a wireless communication system comprising a terminal and a base station, wherein the terminal comprises a communication unit that communicates with a base station that forms a candidate cell to which the terminal is to move, and a control unit that generates a security key for the candidate cell based on a key generation parameter for each of the candidate cells, and the communication unit transmits predicted information regarding the number of security keys to be allocated to the candidate cell.

[0011] The disclosed aspect is a wireless communication method comprising: step A of communicating with a base station that forms a candidate cell to which a terminal is to move; step B of generating a security key for the candidate cell based on a key generation parameter for each of the candidate cells; and step C of transmitting predicted information regarding the number of the security keys to be allocated to the candidate cell.

[0012] FIG. 1 is a diagram illustrating an overall schematic configuration of a wireless communication system 10. FIG. 2 is a diagram illustrating a frequency range used in the wireless communication system 10. FIG. 3 is a diagram illustrating an example configuration of a radio frame, a subframe, and a slot used in the wireless communication system 10. FIG. 4 is a functional block configuration diagram of a UE 200. FIG. 5 is a functional block configuration diagram of a gNB 100. FIG. 6 is a diagram illustrating generation of a security key. FIG. 7 is a diagram illustrating Operation Example 1. FIG. 8 is a diagram illustrating Operation Example 2. FIG. 9 is a diagram illustrating Operation Example 3. FIG. 10 is a diagram illustrating Operation Example 4. FIG. 11 is a diagram illustrating Operation Example 5. FIG. 12 is a diagram illustrating Operation Example 6. FIG. 13 is a diagram illustrating Operation Example 7. FIG. 14 is a diagram illustrating Operation Example 8. FIG. 15 is a diagram illustrating Operation Example 9. FIG. 16 is a diagram illustrating Operation Example 10. FIG. 17 is a diagram illustrating an example of the hardware configuration of the gNB 100 and the UE 200. FIG. 18 is a diagram illustrating an example configuration of a vehicle 2001.

[0013] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or similar reference numerals are used to designate the same functions or configurations, and descriptions thereof will be omitted as appropriate.

[0014] [Embodiment] (1) Overall Schematic Configuration of Wireless Communication System Fig. 1 is an overall schematic configuration diagram of a wireless communication system 10 according to an embodiment. The wireless communication system 10 is a wireless communication system conforming to 5G New Radio (NR) and includes a Next Generation-Radio Access Network 20 (hereinafter, NG-RAN 20) and a terminal 200 (hereinafter, UE (User Equipment) 200).

[0015] The wireless communication system 10 may be a wireless communication system conforming to a system called Beyond 5G, 5G Evolution, or 6G.

[0016] The NG-RAN 20 includes a base station 100 (hereinafter, gNB 100). Note that the specific configuration of the wireless communication system 10, including the number of gNBs 100 and UEs 200, is not limited to the example shown in FIG.

[0017] The NG-RAN 20 actually includes a plurality of NG-RAN nodes, specifically, gNBs (or ng-eNBs), and is connected to a 5G-compliant core network (5GC, not shown). The NG-RAN 20 and the 5GC may be simply referred to as a "network."

[0018] The gNB100 is a radio base station conforming to 5G, and performs 5G radio communication with the UE 200. The gNB100 and UE 200 are capable of supporting Massive MIMO (Multiple-Input Multiple-Output), which generates a more directional beam (BM) by controlling radio signals transmitted from multiple antenna elements, Carrier Aggregation (CA), which aggregates multiple component carriers (CCs), and Dual Connectivity (DC), which simultaneously communicates on two or more transport blocks between the UE and each of two NG-RAN nodes.

[0019] The wireless communication system 10 also supports a plurality of frequency ranges (FR).

[0020] 2, the wireless communication system 10 corresponds to FR1, FR2-1, and FR2-2. The frequency bands of each FR are as follows.

[0021] FR1: 410 MHz to 7.125 GHz; FR2-1: 24.25 GHz to 52.6 GHz; FR2-2: 52.6 GHz to 71 GHz. FR1 may use a sub-carrier spacing (SCS) of 15, 30, or 60 kHz and a bandwidth (BW) of 5 to 100 MHz. FR2-1 is a higher frequency than FR1 and may use an SCS of 60 or 120 kHz (including 240 kHz) and a bandwidth (BW) of 50 to 400 MHz. FR2-2 is a higher frequency than FR2-1 and may use an SCS of 120, 480 kHz, or 960 kHz and a bandwidth (BW) of 400 to 2000 MHz.

[0022] Note that SCS may be interpreted as numerology, which is defined in 3GPP TS38.300 and corresponds to one subcarrier spacing in the frequency domain.

[0023] Furthermore, the wireless communication system 10 also supports frequency bands higher than the FR2-2 frequency band. Specifically, the wireless communication system 10 supports frequency bands above 52.6 GHz up to 71 GHz or 114.25 GHz. For convenience, such high frequency bands may be referred to as "FR2x."

[0024] To solve the problem of increased phase noise in high frequency bands, when using bands above 52.6 GHz, Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) / Discrete Fourier Transform - Spread (DFT-S-OFDM) with larger Sub-Carrier Spacing (SCS) may be applied.

[0025] FIG. 3 shows an example of the configuration of radio frames, subframes, and slots used in the radio communication system 10.

[0026] As shown in Figure 3, one slot consists of 14 symbols, and the larger (wider) the SCS, the shorter the symbol period (and slot period). The SCS is not limited to the interval (frequency) shown in Figure 3. For example, 480 kHz, 960 kHz, etc. may be used.

[0027] Furthermore, the number of symbols constituting one slot does not necessarily have to be 14 (for example, 28 symbols or 56 symbols). Furthermore, the number of slots per subframe may differ depending on the SCS.

[0028] The time direction (t) shown in Fig. 3 may be called a time domain, a symbol period, a symbol time, etc. The frequency direction may be called a frequency domain, a resource block, a subcarrier, a bandwidth part (BWP), etc.

[0029] DMRS is a type of reference signal and is prepared for various channels. Here, unless otherwise specified, it may refer to a downlink data channel, specifically, a DMRS for a PDSCH (Physical Downlink Shared Channel). However, a DMRS for an uplink data channel, specifically, a PUSCH (Physical Uplink Shared Channel), may be interpreted as being the same as a DMRS for a PDSCH.

[0030] The DMRS may be used for channel estimation at the device, for example, as part of coherent demodulation at the UE 200. The DMRS may only be present in resource blocks (RBs) used for PDSCH transmission.

[0031] A DMRS may have multiple mapping types. Specifically, a DMRS has mapping type A and mapping type B. In mapping type A, the first DMRS is placed in the second or third symbol of a slot. In mapping type A, the DMRS may be mapped based on a slot boundary, regardless of where in the slot actual data transmission starts. The reason why the first DMRS is placed in the second or third symbol of a slot may be interpreted as being to place the first DMRS after a control resource set (CORESET).

[0032] In mapping type B, the first DMRS may be placed in the first symbol of the data allocation, i.e., the position of the DMRS may be given relative to where the data is placed, rather than relative to the slot boundary.

[0033] Furthermore, DMRS may have multiple types. Specifically, DMRS has Type 1 and Type 2. Type 1 and Type 2 differ in frequency domain mapping and the maximum number of orthogonal reference signals. Type 1 is a single-symbol DMRS that can output up to four orthogonal signals, while Type 2 is a double-symbol DMRS that can output up to eight orthogonal signals.

[0034] (2) Functional Block Configuration of Wireless Communication System Next, the functional block configuration of the wireless communication system 10 will be described.

[0035] First, the functional block configuration of the UE 200 will be described.

[0036] Fig. 4 is a functional block diagram of UE 200. As shown in Fig. 4, UE 200 includes radio signal transmitting / receiving unit 210, amplifier unit 220, modem unit 230, control signal / reference signal processing unit 240, encoding / decoding unit 250, data transmitting / receiving unit 260, and control unit 270.

[0037] The radio signal transmitting / receiving unit 210 transmits and receives radio signals conforming to NR. The radio signal transmitting / receiving unit 210 supports Massive MIMO, CA that uses a bundle of multiple CCs, and DC that simultaneously communicates between a UE and two NG-RAN nodes.

[0038] In the embodiment, the radio signal transceiver 210 configures a communication unit that communicates with a base station (gNB100) that forms a candidate cell to which the terminal (UE200) is to move. The candidate cell may be a secondary node (SN) in DC or a target cell in handover. The cell may be read as gNB. Cell movement may include movement due to conditional reconfiguration or movement due to lower layer triggered mobility (LTM). Conditional reconfiguration may include conditional handover (CHO), conditional PScell ​​change (CPC), or conditional PScell ​​addition (CPA).

[0039] The amplifier unit 220 is configured by a PA (Power Amplifier) / LNA (Low Noise Amplifier), etc. The amplifier unit 220 amplifies the signal output from the modulation / demodulation unit 230 to a predetermined power level. The amplifier unit 220 also amplifies the RF signal output from the radio signal transmission / reception unit 210.

[0040] The modem unit 230 performs data modulation / demodulation, transmission power setting, resource block allocation, etc. for each predetermined communication destination (gNB 100 or another gNB). The modem unit 230 may apply Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) / Discrete Fourier Transform - Spread (DFT-S-OFDM). Furthermore, DFT-S-OFDM may be used not only for the uplink (UL) but also for the downlink (DL).

[0041] The control signal and reference signal processor 240 executes processing related to various control signals transmitted and received by the UE 200 and processing related to various reference signals transmitted and received by the UE 200 .

[0042] Specifically, the control signal / reference signal processing unit 240 receives various control signals, for example, control signals of a radio resource control layer (RRC), transmitted via a predetermined control channel from the gNB 100. In addition, the control signal / reference signal processing unit 240 transmits various control signals to the gNB 100 via a predetermined control channel.

[0043] The control signal / reference signal processor 240 performs processing using reference signals (RS) such as a Demodulation Reference Signal (DMRS) and a Phase Tracking Reference Signal (PTRS).

[0044] DMRS is a terminal-specific reference signal (pilot signal) known between the base station and the terminal to estimate the fading channel used for data demodulation, while PTRS is a terminal-specific reference signal intended to estimate phase noise, which is an issue in high frequency bands.

[0045] In addition to the DMRS and PTRS, the reference signals may also include a Channel State Information-Reference Signal (CSI-RS), a Sounding Reference Signal (SRS), and a Positioning Reference Signal (PRS) for position information.

[0046] The channels include control channels and data channels, such as a PDCCH (Physical Downlink Control Channel), a PUCCH (Physical Uplink Control Channel), a RACH (Random Access Channel), a Downlink Control Information (DCI) including a Random Access Radio Network Temporary Identifier (RA-RNTI), and a Physical Broadcast Channel (PBCH).

[0047] Furthermore, the data channel includes a PDSCH (Physical Downlink Shared Channel) and a PUSCH (Physical Uplink Shared Channel). Data refers to data transmitted via the data channel. The data channel may be interpreted as a shared channel.

[0048] Here, the control signal and reference signal processor 240 may receive downlink control information (DCI). The DCI includes existing fields for storing DCI Formats, Carrier indicator (CI), BWP indicator, FDRA (Frequency Domain Resource Assignment), TDRA (Time Domain Resource Assignment), MCS (Modulation and Coding Scheme), HPN (HARQ Process Number), NDI (New Data Indicator), RV (Redundancy Version), and the like.

[0049] The value stored in the DCI Format field is an information element that specifies the format of the DCI. The value stored in the CI field is an information element that specifies the CC to which the DCI applies. The value stored in the BWP indicator field is an information element that specifies the BWP to which the DCI applies. The BWP that can be specified by the BWP indicator is set by an information element (BandwidthPart-Config) included in the RRC message. The value stored in the FDRA field is an information element that specifies the frequency domain resource to which the DCI applies. The frequency domain resource is identified by the value stored in the FDRA field and an information element (RA Type) included in the RRC message. The value stored in the TDRA field is an information element that specifies the time domain resource to which the DCI applies. The time domain resource is identified by the value stored in the TDRA field and information elements (pdsch-TimeDomainAllocationList, pusch-TimeDomainAllocationList) included in the RRC message. The time domain resource may be identified by the value stored in the TDRA field and a default table. The value stored in the MCS field is an information element that specifies the MCS to which the DCI applies. The MCS is identified by the value stored in the MCS and an MCS table. The MCS table may be specified by an RRC message or may be determined by RNTI scrambling. The value stored in the HPN field is an information element that specifies the HARQ process to which the DCI is applied. The value stored in the NDI field is an information element for specifying whether the data to which the DCI is applied is initial transmission data. The value stored in the RV field is an information element that specifies the redundancy of the data to which the DCI is applied.

[0050] The encoding / decoding unit 250 performs data division / concatenation and channel coding / decoding for each predetermined communication destination (gNB100 or another gNB).

[0051] Specifically, the encoding / decoding unit 250 divides the data output from the data transmitting / receiving unit 260 into pieces of a predetermined size, performs channel coding on the divided data, decodes the data output from the modem unit 230, and concatenates the decoded data.

[0052] The data transmitter / receiver 260 transmits and receives Protocol Data Units (PDUs) and Service Data Units (SDUs). Specifically, the data transmitter / receiver 260 assembles and disassembles PDUs / SDUs in multiple layers (such as a Medium Access Control layer (MAC), a Radio Link Control layer (RLC), and a Packet Data Convergence Protocol layer (PDCP)). The data transmitter / receiver 260 also performs data error correction and retransmission control based on Hybrid Automatic Repeat Request (HARQ).

[0053] The control unit 270 controls each functional block constituting the UE 200. In the embodiment, the control unit 270 generates a security key (K) for a candidate cell based on a key generation parameter (e.g., an sk counter value or an NCC (Next Hop Chaining Counter) parameter) for each candidate cell. SN Specifically, the control unit 270 configures a control unit that generates information about the gNB 100 (K gNB ) and the key generation parameters, a security key (K SN ) to generate information about gNB100 (K gNB ) may be set by the RRC. The key generation parameters may be updated as the user moves between cells.

[0054] In the embodiment, the control unit 270 may assume a scheme (Subsequent CPC) in which the configuration information (CPC config) regarding the candidate cell is continued to be held even when the movement to the candidate cell is completed in CHO, CPC, CPA, LTM, etc. According to the Subsequent CPC, it is possible to suppress the reconfiguration and discarding of the configuration information regarding the candidate cell.

[0055] First, the control unit 270 may instruct the radio signal transceiver unit 210 to transmit key-related information related to the key generation parameters. In other words, the radio signal transceiver unit 210 transmits the key-related information related to the key generation parameters. The key-related information may be transmitted to the MN. The key-related information may be transmitted to a Target SN (hereinafter, T-SN) via the MN. The key-related information may be included in an RRC message (e.g., RRCReconfigurationComplete) to the MN. The key-related information may be transmitted to a Target gNB (hereinafter, T-gNB). The key-related information may be included in an RRC message (e.g., RRCReconfigurationComplete) to the T-gNB.

[0056] Here, the key-related information may include the following information:

[0057] In option 1-1, the key related information may include key generation parameters used to generate the security key. That is, the key related information may include the K SN sk counter value used to generate K for the candidate cell SN The sk counter value may be simply referred to as the sk counter, and the NCC parameter may be simply referred to as the NCC.

[0058] In option 1-2, the key-related information may include information indicating exhaustion of key generation parameters allocated to the candidate cells, where the number of key generation parameters (i.e., security keys generated based on the key generation parameters) may be different for each candidate cell or may be the same for each candidate cell.

[0059] Note that Option 1-1 and Option 1-2 may be combined.

[0060] Second, the control unit 270 may instruct the radio signal transceiver unit 210 to transmit predicted information regarding the number of security keys to be allocated to the candidate cell. In other words, the radio signal transceiver unit 210 transmits predicted information regarding the number of security keys to be allocated to the candidate cell. The predicted information may be included in an RRC message (e.g., UE Assistance Information).

[0061] Here, the prediction information may include the following information.

[0062] In option 2-1, the prediction information may include information indicating a predicted trajectory of a cell in which UE 200 moves (Predicted UE's trajectory). The Predicted UE's trajectory may include future physical location information of UE 200 (e.g., latitude, longitude, altitude, etc.), a cell ID of a PCell or a PSCell where UE 200 will stay in the future, and a time during which UE 200 will stay in the PCell or the PSCell. The Predicted UE's trajectory may be predicted by UE 200 using an AIML model (AI (Artificial Intelligence) or ML (Machine Learning)).

[0063] In option 2-2, the prediction information may include information indicating the number of security keys to be allocated to the candidate cell. The information indicating the number of security keys may be determined based on a predicted UE's trajectory. For example, the number of security keys to be allocated to a candidate cell in which the movement frequency of the UE 200 is predicted to be higher than a threshold may be greater than the number of security keys to be allocated to a candidate cell in which the movement frequency of the UE 200 is predicted to be lower than the threshold.

[0064] Note that Option 1-1 and Option 1-2 may be combined.

[0065] Secondly, we will explain the functional block configuration of gNB100.

[0066] Fig. 5 is a functional block diagram of the gNB 100. As shown in Fig. 5, the gNB 100 has a receiving unit 110, a transmitting unit 120, and a control unit 130.

[0067] The receiving unit 110 receives various signals from the UE 200. The receiving unit 110 may receive an UL signal via a PUCCH or a PUSCH.

[0068] The transmitter 120 transmits various signals to the UE 200. The transmitter 120 may transmit the DL signal via the PDCCH or the PDSCH.

[0069] In the embodiment, the receiving unit 110 and the transmitting unit 120 constitute a communication unit that communicates with the terminal (UE 200).

[0070] The control unit 130 controls the gNB 100. In an embodiment, the control unit 130 configures a control unit that assumes that the terminal generates security keys for candidate cells based on key generation parameters for each candidate cell to which the terminal is to move.

[0071] First, the control unit 130 may receive key-related information related to the key generation parameters. In other words, the receiving unit 110 may receive key-related information related to the key generation parameters.

[0072] Second, the control unit 130 may determine the number of security keys to be allocated to the candidate cell based on a predicted trajectory of the cell in which the UE 200 will move. The predicted trajectory of the cell in which the UE 200 will move may be predicted by the gNB 100 using an AIML model (AI or ML) based on a measurement report received from the UE 200. The predicted trajectory of the cell in which the UE 200 will move may be predicted based on mobility history information (visitedCellInfoList IE) of the UE 200 or a UE history information IE. The UE history information IE may include a cell ID of a cell in which the UE 200 has previously visited and a time during which the UE 200 has visited the cell. The mobility history information or the UE history information IE may be received from the UE 200. The predicted trajectory of the cell in which the UE 200 will move may be received from the UE 200. For example, the number of security keys allocated to a candidate cell where the movement frequency of UE200 is predicted to be higher than a threshold may be greater than the number of security keys allocated to a candidate cell where the movement frequency of UE200 is predicted to be lower than a threshold.

[0073] (3) Generation of Security Keys The generation of security keys will be explained below. Here, assuming DC, a case where SN1, SN2, and SN3 exist will be illustrated.

[0074] As shown in the upper part of Figure 6, SN1 is assigned security keys Security key 1, Security key 2, and Security key 3. Security key 1 is generated based on sk counter 1, Security key 2 is generated based on sk counter 2, and Security key 3 is generated based on sk counter 3. SN2 is assigned security keys Security key 4, Security key 5, and Security key 6. Security key 4 is generated based on sk counter 4, Security key 5 is generated based on sk counter 5, and Security key 6 is generated based on sk counter 6. SN3 is assigned security keys Security key 7, Security key 8, and Security key 9. Security key 7 is generated based on sk counter 7, Security key 8 is generated based on sk counter 8, and Security key 9 is generated based on sk counter 9.

[0075] As shown in the lower part of Figure 6, assume a case where UE 200 moves in the order of SN1, SN2, SN3, SN2, SN3, SN2, and SN1. In such a case, UE 200 updates the sk counter for the candidate cell every time the UE moves to another cell, and generates a security key for the candidate cell based on the updated sk counter. When two or more security keys (sk counters) are allocated to the candidate cell, UE 200 may update the sk counter based on a predetermined rule. The predetermined rule may be a rule that uses the sk counter values ​​in ascending order, or a rule that uses the sk counter values ​​in descending order.

[0076] If such a case is assumed, the following issues can be considered.

[0077] First, since gNB200 (candidate cell) does not know the sk counter value used by UE200 in generating the security key, there is a possibility that the understanding of the sk counter value differs between UE200 and gNB100.

[0078] Second, since the number of security keys that can be allocated to the gNB200 (candidate cell) is limited, it is expected that the security keys allocated to the candidate cell will be exhausted when the UE200 moves frequently to the candidate cell, etc. Therefore, after the security keys allocated to the candidate cell are exhausted, a problem occurs in which the security keys used between the UE200 and the gNB200 (candidate cell) are reused.

[0079] Third, because the number of security keys that can be allocated to the gNB200 (candidate cells) is limited, it is unclear how many security keys should be allocated to each candidate cell. In other words, it is unclear how many sk counters should be set in the UE200 when setting the sk counters used to generate the security keys to be allocated to each candidate cell in the UE200.

[0080] Although the above case is exemplified as DC, the same applies to Handover. In Handover, the sk counter may be read as NCC.

[0081] To solve the above-mentioned problems, the following operations may be performed.

[0082] (4) Operational Examples An operational example will be described below. As the operational example, the following variations are conceivable.

[0083] (4.1) Operation Example 1 In operation example 1, we will explain the CPC to T-SN1, the CPA of T-SN1, the CPC to T-SN2, and the CPA of T-SN2 when connected to a Source SN (hereinafter referred to as S-SN).

[0084] As shown in Fig. 7, in step S10A, the MN sends an SgNB addition request to T-SN 1. The SgNB addition request includes one or more security keys allocated to T-SN 1. In step S11A, the T-SN 1 sends an SgNB addition request Ack to the MN.

[0085] In step S10B, the MN sends an SgNB addition request to T-SN 2. The SgNB addition request includes one or more security keys allocated to T-SN 2. In step S11B, T-SN 2 sends an SgNB addition request Ack to the MN.

[0086] In step S12, the MN transmits RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes configuration information (SN RRCReconfig) for candidate cells (S-SN, T-SN1, T-SN2). The SN RRCReconfig may be read as CPC config. Furthermore, the RRC Reconfiguration includes one or more sk counters used to generate one or more security keys allocated to T-SN1 and one or more sk counters used to generate one or more security keys allocated to T-SN2.

[0087] In step S13, the UE 200 transmits an RRC Reconfiguration Complete to the MN.

[0088] In step S14, the UE 200 detects that the conditions for performing a connection to the T-SN1 are met.

[0089] In step S15, the UE 200 transmits an RRC Reconfiguration Complete to the MN. The RRC Reconfiguration Complete includes key-related information. The RRC Reconfiguration Complete may include an sk counter used to generate a security key for T-SN1. The RRC Reconfiguration Complete may include information indicating exhaustion of the security key (sk counter) allocated to T-SN1.

[0090] In step S16, the MN sends an SgNB Reconfiguration Complete to the T-SN 1. The SgNB Reconfiguration Complete may include the key-related information received in step S15.

[0091] In step S17, the UE 200 transmits the RACH to the T-SN 1. In other words, the UE 200 performs a random access procedure for the T-SN 1.

[0092] In step S18, the UE 200 retains the configuration information (CPC config) of the candidate cells (S-SN, T-SN1, T-SN2) without deleting it. The UE 200 retains the sk counters of the candidate cells (S-SN, T-SN1, T-SN2) without deleting it.

[0093] In step S21, the UE 200 detects that the conditions for performing a connection to the T-SN2 are met.

[0094] In step S22, the UE 200 generates a security key (New K_SN) for T-SN2. Specifically, the UE 200 generates a sk counter and K gNB Based on this, a security key for T-SN2 is generated.

[0095] In step S23, the UE 200 transmits an RRC Reconfiguration Complete to the MN. The RRC Reconfiguration Complete includes key-related information. The RRC Reconfiguration Complete may include an sk counter used to generate a security key for T-SN2. The RRC Reconfiguration Complete may include information indicating exhaustion of the security key (sk counter) allocated to T-SN2. The information indicating exhaustion of the security key (sk counter) allocated to T-SN2 may be information indicating that there are no security keys (sk counters) available for use in T-SN2, or may be information indicating that the security key (sk counter) available for use in T-SN2 is the last one.

[0096] In step S24, the MN sends an SgNB Reconfiguration Complete to the T-SN 2. The SgNB Reconfiguration Complete may include the key-related information received in step S23.

[0097] In step S25, the UE 200 transmits the RACH to the T-SN 2. In other words, the UE 200 performs a random access procedure for the T-SN 2. The security key (New K_SN) generated in step S22 is used in the communication between the UE 200 and the T-SN 2.

[0098] In the first operation example, key-related information (the sk counter used to generate a security key for the T-SN) is transmitted to the T-SN. According to this configuration, the UE 200 and the gNB 100 (candidate cell) can have a common understanding of the sk counter used to generate the security key.

[0099] (4.2) Operation Example 2 In Operation Example 2, a case where Operation Example 1 is replaced with LTM will be described. Figure 8 is the same as Figure 7 except that steps S31 and S32 are executed instead of step S14 shown in Figure 7, and steps S33 and S34 are executed instead of step S21 shown in Figure 7. In the following, explanations of steps that are the same as those in Figure 7 will be omitted.

[0100] As shown in Fig. 8, in step S31, UE 200 transmits an L1 measurement report to S-SN. In step S32, the S-SN transmits an LTM cell switch command to UE 200. Here, a case will be illustrated in which the LTM cell switch command is a command instructing movement from S-SN to T-SN1.

[0101] In step S33, UE 200 transmits an L1 measurement report to T-SN 1. In step S34, T-SN 1 transmits an LTM cell switch command to UE 200. Here, a case will be illustrated in which the LTM cell switch command is a command instructing movement from T-SN 1 to T-SN 2.

[0102] In the operation example 2, similarly to the operation example 1, key-related information (sk counter used to generate a security key for the T-SN) is transmitted to the T-SN. According to such a configuration, it is possible to have a common understanding between the UE 200 and the gNB 100 (candidate cell) regarding the sk counter used to generate a security key.

[0103] (4.3) Operation Example 3 In Operation Example 3, a case will be described in which the MN acquires information indicating the depletion of the security key (sk counter) allocated to the candidate cell in Operation Example 1 or Operation Example 2.

[0104] 9 , in step S28, the MN reallocates the sk counter(s) and the security key(s) for each candidate cell in accordance with key-related information including information indicating the depletion of the security key (sk counter) allocated to the candidate cell. The MN may obtain the key-related information from the UE 200.

[0105] In step S10X, the MN sends an SgNB addition request to T-SN 1. The SgNB addition request includes one or more security keys reallocated to T-SN 1. In step S11X, T-SN 1 sends an SgNB addition request Ack to the MN.

[0106] In step S10Y, the MN sends an SgNB addition request to T-SN2. The SgNB addition request includes one or more security keys reallocated to T-SN2. In step S11Y, T-SN2 sends an SgNB addition request Ack to the MN.

[0107] In step S29, the MN transmits RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes one or more sk counters used to generate one or more security keys reallocated to T-SN1 and one or more sk counters used to generate one or more security keys reallocated to T-SN2. Because the configuration information (SN RRCReconfig) of the candidate cells (S-SN, T-SN1, T-SN2) has already been transmitted, the RRC Reconfiguration does not need to include the configuration information (SN RRCReconfig) of the candidate cells (S-SN, T-SN1, T-SN2). However, the RRC Reconfiguration may include the configuration information (SN RRCReconfig) of the candidate cells (S-SN, T-SN1, T-SN2).

[0108] In the third exemplary operation, the security key (sk counter) allocated to the candidate cell may be updated every time the UE moves to the candidate cell. The UE 200 may have a counter for each candidate cell that counts the used security key (sk counter).

[0109] In the third operation example, a case is assumed in which information indicating the exhaustion of a security key (sk counter) allocated to a candidate cell is transmitted from the UE 200. However, the third operation example is not limited to this. For example, the MN may have a counter for counting used security keys (sk counter) for each candidate cell. The SN may have a counter for counting used security keys (sk counter). In such a case, when the SN detects the exhaustion of a security key (sk counter) using the counter for counting used security keys (sk counter), the SN may transmit information indicating the exhaustion of the security key (sk counter) to the MN.

[0110] In the third operation example, the security key (sk counter) is reallocated for each candidate cell in accordance with information indicating the depletion of the security key (sk counter) allocated to the candidate cell. This configuration can solve the problem of security key reuse. In other words, it is possible to appropriately maintain security between the UE 200 and the gNB 100.

[0111] (4.4) Operation Example 4 In operation example 4, CHO to T-gNB1 and CHO to T-gNB2 when connected to a Source gNB (hereinafter, S-gNB) are described.

[0112] As shown in Figure 10, in step S40A, the S-gNB sends a Handover request to the T-gNB1. The Handover request includes one or more Security keys allocated to the T-gNB1. In step S41A, the T-gNB1 sends a Handover request Ack to the S-gNB.

[0113] In step S40B, the S-gNB sends a Handover request to the T-gNB2. The Handover request includes one or more Security keys allocated to the T-gNB2. In step S41B, the T-gNB2 sends a Handover request Ack to the S-gNB.

[0114] In step S42, the S-gNB transmits RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes configuration information (gNB RRCReconfig) for the candidate cells (S-gNB, T-gNB1, T-gNB2). The gNB RRCReconfig may be read as "Target config." Furthermore, the RRC Reconfiguration includes one or more NCCs used to generate one or more security keys allocated to the T-gNB1 and one or more NCCs used to generate one or more security keys allocated to the T-gNB2.

[0115] In step S43, UE200 detects that the conditions for performing a connection to T-gNB1 are met.

[0116] In step S44, the UE 200 transmits the RACH to the T-gNB 1. In other words, the UE 200 performs a random access procedure for the T-gNB 1.

[0117] In step S45, UE200 transmits an RRC Reconfiguration Complete to T-gNB1. The RRC Reconfiguration Complete includes key-related information. The RRC Reconfiguration Complete may include an NCC used to generate a security key for T-gNB1. The RRC Reconfiguration Complete may include information indicating exhaustion of the security key (NCC) allocated to T-gNB1.

[0118] In step S46, UE200 retains the configuration information (Target config) of the candidate cells (S-gNB, T-gNB1, T-gNB2) without deleting it. UE200 retains the NCC of the candidate cells (S-gNB, T-gNB1, T-gNB2) without deleting it.

[0119] In step S51, UE200 detects that the conditions for performing a connection to T-gNB2 are met.

[0120] In step S52, the UE 200 generates a security key (New K_gNB) for the T-gNB2. Specifically, the UE 200 generates an NCC and K_gNB corresponding to the T-gNB2. gNB Based on this, a security key for the T-gNB2 is generated.

[0121] In step S53, UE 200 transmits the RACH to T-gNB2. In other words, UE 200 performs a random access procedure to T-gNB2. The security key (New K_gNB) generated in step S52 is used in communication between UE 200 and T-gNB2.

[0122] In step S54, UE200 transmits an RRC Reconfiguration Complete to T-gNB2. The RRC Reconfiguration Complete includes key-related information. The RRC Reconfiguration Complete may include an NCC used to generate a security key for T-gNB2. The RRC Reconfiguration Complete may include information indicating the exhaustion of security keys (NCCs) allocated to T-gNB2. The information indicating the exhaustion of security keys (NCCs) allocated to T-gNB2 may be information indicating that there are no security keys (NCCs) available for use by T-gNB2, or may be information indicating that the last security key (NCC) available for use by T-gNB2 is remaining.

[0123] In operation example 4, key-related information (NCC used to generate a security key for the T-gNB) is transmitted to the T-gNB. With this configuration, it is possible for the UE 200 and the gNB 100 (candidate cell) to have a common understanding of the NCC used to generate the security key.

[0124] (4.5) Operation Example 5 In Operation Example 5, a case where Operation Example 4 is replaced with LTM will be described. Figure 11 is the same as Figure 10 except that steps S61 and S62 are executed instead of step S43 shown in Figure 10, and steps S63 and S64 are executed instead of step S51 shown in Figure 10. In the following, explanations of steps that are the same as those in Figure 10 will be omitted.

[0125] As shown in Fig. 11 , in step S61, UE200 transmits an L1 measurement report to the S-gNB. In step S62, the S-gNB transmits an LTM cell switch command to UE200. Here, a case will be illustrated in which the LTM cell switch command is a command instructing movement from the S-gNB to T-gNB1.

[0126] In step S63, UE200 transmits an L1 measurement report to T-gNB1. In step S64, T-gNB1 transmits an LTM cell switch command to UE200. Here, a case will be illustrated in which the LTM cell switch command is a command instructing movement from T-gNB1 to T-gNB2.

[0127] In operation example 5, key-related information (NCC used to generate a security key for the T-gNB) is transmitted to the T-gNB, similarly to operation example 4. With this configuration, it is possible for the UE 200 and the gNB 100 (candidate cell) to have a common understanding of the NCC used to generate the security key.

[0128] (4.6) Operation Example 6 In Operation Example 6, a case is described in which the S-gNB acquires information indicating the depletion of the security key (NCC) allocated to the candidate cell in Operation Example 4 or Operation Example 5.

[0129] 12, in step S58, the S-gNB reallocates NCC(s) and security key(s) for each candidate cell according to key-related information including information indicating the depletion of security keys (NCCs) allocated to the candidate cells. The S-gNB may obtain the key-related information from the T-gNB that receives the key-related information.

[0130] In step S40X, the S-gNB sends a Handover request to the T-gNB1. The Handover request includes one or more Security keys reallocated to the T-gNB1. In step S41X, the T-gNB1 sends a Handover request Ack to the S-gNB.

[0131] In step S40Y, the S-gNB sends a Handover request to the T-gNB2. The Handover request includes one or more Security keys reallocated to the T-gNB2. In step S41Y, the T-gNB2 sends a Handover request Ack to the S-gNB.

[0132] In step S59, the S-gNB transmits RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes one or more NCCs used to generate one or more security keys reallocated to the T-gNB1 and one or more NCCs used to generate one or more security keys reallocated to the T-gNB2. Because the configuration information (gNB RRCReconfig) of the candidate cells (S-gNB, T-gNB1, T-gNB2) has already been transmitted, the RRC Reconfiguration does not need to include the configuration information (gNB RRCReconfig) of the candidate cells (S-gNB, T-gNB1, T-gNB2). However, the RRC Reconfiguration may include the configuration information (gNB RRCReconfig) of the candidate cells (S-gNB, T-gNB1, T-gNB2).

[0133] In the sixth operation example, the security key (NCC) allocated to the candidate cell may be updated every time the UE moves to the candidate cell. The UE 200 may have a counter for each candidate cell that counts the number of used security keys (NCC).

[0134] In the sixth operational example, a case is assumed in which information indicating the depletion of a security key (NCC) allocated to a candidate cell is transmitted from the UE 200. However, the sixth operational example is not limited to this. For example, the S-gNB may have a counter for counting used security keys (NCC) for each candidate cell. The T-gNB may have a counter for counting used security keys (NCC). In such a case, when the T-gNB detects the depletion of a security key (NCC) using the counter for counting used security keys (NCC), the T-gNB may transmit information indicating the depletion of the security key (NCC) to the S-gNB.

[0135] In the sixth operation example, the security key (NCC) is reallocated for each candidate cell in response to information indicating the depletion of the security key (NCC) allocated to the candidate cell. This configuration can solve the problem of security key reuse. In other words, it is possible to properly maintain security between the UE 200 and the gNB 100.

[0136] (4.7) Operation Example 7 The following describes a case where the gNB100 specifies the number of security keys to be allocated to the T-SN in the CPA or CPC. The predicted trajectory of the UE200 is predicted using the AIML function of the gNB100 (here, the MN). Operation Example 7 may be applied to the above-mentioned Operation Examples 1 to 3.

[0137] 13, in step S70A, the UE 200 transmits a measurement report to the MN. The measurement report may be an L1 measurement report or an L3 measurement report.

[0138] In step S71A, the MN generates an AIML model (AI model) based on the measurement report. The AIML model is obtained by learning the correlation between the measurement report and the trajectory of the cell in which the UE 200 moves.

[0139] In step S72A, the UE 200 transmits a measurement report to the MN. The measurement report may be an L1 measurement report or an L3 measurement report.

[0140] In step S73A, the MN inputs the Measurement report into the AIML model to identify the Measurement report and information indicating the predicted trajectory of the cell in which the UE 200 will move (Predicted UE's trajectory).

[0141] In step S74A, the MN determines the number of security key(s) (sk counter(s)) to be allocated to the candidate cell based on the predicted UE's trajectory. The MN may predict the number of times the UE 200 will access the candidate cell based on the predicted UE's trajectory. The number of security key(s) (sk counter(s)) to be allocated to the candidate cell may be interpreted as the number of times the UE 200 will access the candidate cell.

[0142] In step S75A, the MN sends an SgNB addition request to the T-SN. The SgNB addition request includes the number of security keys identified in step S74A.

[0143] In step S76A, the MN transmits an RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes the number of sk counter(s) identified in step S74A.

[0144] In the seventh operation example, the number of security keys (sk counters) to be allocated to the candidate cell is determined based on the predicted UE's trajectory. With this configuration, it is possible to appropriately prevent the depletion of security keys (sk counters) for the candidate cell.

[0145] (4.8) Operation Example 8 Hereinafter, a case will be described in which UE 200 specifies the number of security keys to be allocated to T-SN in CPA or CPC. The predicted trajectory of UE 200 is predicted using the AIML function of UE 200. Operation Example 8 may be applied to the above-mentioned Operation Examples 1 to 3.

[0146] 14, in step S80A, the UE 200 generates an AIML model (AI model) based on the content of the measurement report (measurement result) to be transmitted to the MN. The AIML model is obtained by learning the correlation between the measurement report and the trajectory of the cell in which the UE 200 moves.

[0147] In step S81A, the MN inputs the contents of the Measurement report (Measurement result) to be transmitted to the MN into the AIML model, thereby identifying the Measurement result and information indicating the predicted trajectory of the cell in which the UE 200 will move (Predicted UE's trajectory).

[0148] In step S82A, the UE 200 determines the number of security keys (sk counter(s)) to be allocated to the candidate cell based on the predicted UE's trajectory.

[0149] In step S83A, the UE 200 transmits a Report to the MN. The Report may include the Predicted UE's trajectory predicted in step S81A. The Report may also include the number of Security key(s) (sk counter(s)) identified in step S82A.

[0150] In step S84A, the MN transmits an SgNB addition request to the T-SN. The SgNB addition request includes the number of security keys specified by the Report received in step S83A.

[0151] In step S85A, the MN transmits an RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes the number of sk counter(s) specified by the Report received in step S83A.

[0152] In the operation example 8, a case where the number of security key(s) (sk counter(s)) is determined by the UE 200 has been exemplified. However, the operation example 8 is not limited to this. The number of security key(s) (sk counter(s)) may be determined by the MN that receives the predicted UE's trajectory.

[0153] In operation example 8, the number of security key(s) (sk counter(s)) to be allocated to the candidate cell is determined based on the predicted UE's trajectory. With this configuration, it is possible to appropriately prevent the depletion of security key(s) (sk counter(s)) for the candidate cell.

[0154] (4.9) Operation Example 9 The following describes a case in which the gNB100 specifies the number of security keys to be allocated to the T-gNB in ​​LTM. The predicted trajectory of the UE200 is predicted using the AIML function of the gNB100 (here, S-gNB). Operation Example 9 may be applied to the above-mentioned Operation Examples 4-6.

[0155] 15, in step S70B, the UE 200 transmits a Measurement report to the S-gNB. The Measurement report may be an L1 Measurement report or an L3 Measurement report.

[0156] In step S71B, the S-gNB generates an AIML model (AI model) based on the measurement report. The AIML model is obtained by learning the correlation between the measurement report and the trajectory of the cell in which the UE 200 moves.

[0157] In step S72B, the UE 200 transmits a measurement report to the S-gNB. The measurement report may be an L1 measurement report or an L3 measurement report.

[0158] In step S73B, the S-gNB inputs the Measurement report into an AIML model to identify the Measurement report and information indicating the predicted trajectory of the cell in which UE200 will move (Predicted UE's trajectory).

[0159] In step S74B, the S-gNB determines the number of security key(s) (NCC(s)) to allocate to the candidate cell based on the predicted UE's trajectory.

[0160] In step S75B, the S-gNB sends an SgNB addition request to the T-gNB. The SgNB addition request includes the number of security keys identified in step S74B.

[0161] In step S76B, the S-gNB transmits RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes the number of NCC(s) identified in step S74B.

[0162] In the ninth operation example, the number of security key(s) (NCC(s)) to be allocated to the candidate cell is determined based on the predicted UE's trajectory. With this configuration, it is possible to appropriately prevent the depletion of security key(s) (NCC(s)) for the candidate cell.

[0163] (4.10) Operation Example 10 In the following, a case will be described in which UE200 specifies the number of security keys to be allocated to a T-gNB in ​​LTM. The predicted trajectory of UE200 is predicted using the AIML function of UE200. Operation Example 10 may be applied to the above-mentioned Operation Examples 4-6.

[0164] 16, in step S80B, UE200 generates an AIML model (AI model) based on the content of the Measurement report (Measurement result) to be transmitted to the S-gNB. The AIML model is obtained by learning the correlation between the Measurement report and the trajectory of the cell in which UE200 moves.

[0165] In step S81B, the S-gNB inputs the contents of the Measurement report (Measurement result) to be sent to the S-gNB into the AIML model, thereby identifying the Measurement result and information indicating the predicted trajectory of the cell in which UE200 will move (Predicted UE's trajectory).

[0166] In step S82B, the UE 200 determines the number of security keys (NCC(s)) to be allocated to the candidate cells based on the predicted UE's trajectory.

[0167] In step S83B, UE 200 transmits a Report to the S-gNB. The Report may include the Predicted UE's trajectory predicted in step S81B. The Report may include the number of Security key(s) (NCC(s)) identified in step S82B.

[0168] In step S84B, the S-gNB sends an SgNB addition request to the T-gNB. The SgNB addition request includes the number of security keys specified by the Report received in step S83B.

[0169] In step S85B, the S-gNB transmits an RRC Reconfiguration to the UE 200. The RRC Reconfiguration includes the number of NCC(s) specified by the Report received in step S83B.

[0170] Operation example 10 illustrates a case where the number of security key(s) (NCC(s)) is determined by UE 200. However, operation example 8 is not limited to this. The number of security key(s) (NCC(s)) may be determined by an S-gNB that receives the predicted UE's trajectory.

[0171] In the tenth operation example, the number of security key(s) (NCC(s)) to be allocated to the candidate cell is determined based on the predicted UE's trajectory. With this configuration, it is possible to appropriately prevent the depletion of security key(s) (NCC(s)) for the candidate cell.

[0172] (4.11) Operation Example 11 Other operation examples will be described in Operation Example 11. Other operation examples include the following.

[0173] In Operation Example 11-1, in the above-described Operation Example 1-3, the MN may store the correspondence relationship between the sk counter and the security key. Similarly, the SN may store the correspondence relationship between the sk counter and the security key.

[0174] In Operation Example 11-2, it may be assumed that in the above-described Operation Example 1-3, the UE 200 and the gNB 100 (MN or SN) generate a security key by using an sk counter determined based on a predetermined rule. The predetermined rule may be a rule in which the sk counter values ​​are used in ascending order, or a rule in which the sk counter values ​​are used in descending order.

[0175] In operation example 11-3, in the above-mentioned operation example 1-3, UE200 and gNB100 (MN or SN) may assume that UE200 generates a security key using an sk counter defined based on rules notified by gNB100.

[0176] In operation example 11-4, in the above-described operation example 4-6, the S-gNB may store the correspondence relationship between the NCC and the security key. Similarly, the T-gNB may store the correspondence relationship between the NCC and the security key.

[0177] In operation example 11-5, it may be assumed that in operation example 4-6 described above, UE200 and gNB100 (S-gNB or T-gNB) generate a security key by UE200 using an NCC determined based on a predetermined rule. The predetermined rule may be a rule to use NCC values ​​in ascending order, or may be a rule to use NCC values ​​in descending order.

[0178] In operation example 11-6, in the above-mentioned operation example 4-6, UE200 and gNB100 (S-gNB or T-gNB) may assume that UE200 generates a security key using an NCC defined based on rules notified by gNB100.

[0179] (5) Actions and Effects In the embodiments, the UE 200 transmits a key generation parameter (e.g., an sk counter or an NCC) used to generate a security key for a T-SN (e.g., operation examples 1, 2, 4, and 5). According to this configuration, the UE 200 and the gNB 100 (candidate cell) can have a common understanding of the key generation parameter used to generate the security key.

[0180] In the embodiment, the UE 200 transmits information indicating the depletion of a security key (sk counter / NCC) allocated to a candidate cell (for example, operation examples 3 and 6). With this configuration, the gNB 100 can reassign the security key (sk counter), thereby resolving the problem of security key reuse and appropriately maintaining security between the UE 200 and the gNB 100.

[0181] In the embodiment, the number of security keys (sk counter(s) / NCC(s)) to be allocated to the candidate cell is determined based on the predicted UE's trajectory. With this configuration, it is possible to appropriately prevent the depletion of security keys (NCC(s)) for the candidate cell.

[0182] (6) Other Embodiments The contents of the present invention have been described above in accordance with the embodiments, but it will be obvious to those skilled in the art that the present invention is not limited to these descriptions and that various modifications and improvements are possible.

[0183] In the above disclosure, a case where key-related information is included in the RRC Reconfiguration Complete has been exemplified. However, the above disclosure is not limited to this. The key-related information may be included in an RRC message other than the RRC Reconfiguration Complete.

[0184] In the above disclosure, configure, activate, update, indicate, enable, specify, and select may be interchangeable. Similarly, link, associate, correspond, and map may be interchangeable, and allocate, assign, monitor, and map may be interchangeable.

[0185] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0186] The block diagrams (FIGS. 4 and 5) used to explain the above-described embodiments show functional blocks. These functional blocks (components) are realized by any combination of hardware and / or 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 directly or indirectly connected (e.g., wired, wireless, etc.) and these multiple devices. The functional block may also be realized by combining software with the single device or multiple devices.

[0187] 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, regard, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, 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 each is implemented.

[0188] Furthermore, the above-described gNB 100 and UE 200 (the devices) may function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 17 is a diagram showing an example of the hardware configuration of the devices. As shown in Figure 17, the devices may be configured as a computer including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0189] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the apparatus 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.

[0190] Each functional block of the device (see FIGS. 4 and 5) is realized by any hardware element of the computer device or a combination of the hardware elements.

[0191] In addition, each function of the device is realized by loading specified software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication via communication device 1004, and control at least one of reading and writing data in memory 1002 and storage 1003.

[0192] The processor 1001 controls the entire computer by running, for example, an operating system, and may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, and registers.

[0193] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. Furthermore, the various processes described above may be executed by one processor 1001, or may 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.

[0194] The memory 1002 is a computer-readable recording medium and may be configured by at least one of, for example, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 may store a program (program code), a software module, etc., capable of executing a method according to an embodiment of the present disclosure.

[0195] Storage 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a Compact Disc ROM (CD-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. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned recording medium may be, for example, a database, a server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0196] 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 called, for example, a network device, a network controller, a network card, or a communication module.

[0197] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize, for example, at least one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

[0198] The input device 1005 is an input device (e.g., 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 (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0199] Furthermore, each device such as the processor 1001 and the memory 1002 is connected to 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.

[0200] Furthermore, the device 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, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0201] 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., 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.

[0202] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, a 4th generation mobile communication system (4G), a 5th generation mobile communication system (5G), a 6th generation mobile communication system (6G), an xth generation mobile communication system (xG) (where x is, for example, an integer or a decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other suitable system, and a next-generation system extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G) may also be applied.

[0203] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0204] In the present disclosure, a specific operation described as being performed by a base station may, in some cases, be performed by its upper node. It is clear that in a network consisting of one or more network nodes having a base station, various operations performed for communication with a terminal may be performed by at least one of the base station and another network node other than the base station (such as, but not limited to, an MME or an S-GW). While the above example illustrates a case in which there is one other network node other than the base station, a combination of multiple other network nodes (such as an MME and an S-GW) may also be used.

[0205] Information, signals (information, etc.) 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.

[0206] The input and output information may be stored in a specific location (for example, a memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added. The output information may be deleted. The input information may be transmitted to another device.

[0207] 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).

[0208] The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to explicit notification, but may be implicit (e.g., not notifying the predetermined information).

[0209] 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.

[0210] 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.

[0211] 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.

[0212] Note that terms described 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.

[0213] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0214] 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.

[0215] 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.

[0216] In this disclosure, terms such as "base station (BS)," "radio base station," "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.

[0217] A base station can accommodate one or more (e.g., three) cells (also called sectors). 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 services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0218] The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage area.

[0219] 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.

[0220] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0221] 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.

[0222] 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 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 also 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 Internet of Things (IoT) device such as a sensor.

[0223] Furthermore, a base station in the present disclosure may be read as a mobile station (user terminal, the same applies hereinafter). For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the mobile station may be configured to have the functions of a base station. 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.

[0224] Similarly, a mobile station in the present disclosure may be interpreted as a base station, in which case the base station may have the functions of a mobile station.

[0225] A radio frame may be composed of one or more frames in the time domain, each of which may be called a subframe.

[0226] A subframe may further be composed of one or more slots in the time domain, and may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0227] Numerology may be a communication parameter applied to the transmission and / or reception of a signal or channel, and may indicate, for example, at least one of a subcarrier spacing (SCS), a bandwidth, a symbol length, a cyclic prefix length, a transmission time interval (TTI), a number of symbols per TTI, a radio frame structure, a particular filtering operation performed by a transceiver in the frequency domain, a particular windowing operation performed by a transceiver in the time domain, etc.

[0228] A slot may consist of one or more symbols in the time domain (such as Orthogonal Frequency Division Multiplexing (OFDM) symbols, Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols, etc.) A slot may be a numerology-based time unit.

[0229] A slot may include multiple minislots. Each minislot may consist of one or multiple symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0230] The radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals, and may be referred to by other names corresponding to the radio frame, subframe, slot, minislot, and symbol.

[0231] For example, one subframe may be referred to as a transmission time interval (TTI), multiple consecutive subframes may be referred to as a TTI, or one slot or one minislot may be referred to as a TTI. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be referred to as a slot, minislot, etc. instead of a subframe.

[0232] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station schedules each user terminal to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) in TTI units. Note that the definition of TTI is not limited to this.

[0233] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0234] In addition, when one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Furthermore, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0235] A TTI having a time length of 1 ms may be called a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0236] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0237] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may be determined based on numerology.

[0238] The time domain of an RB may include one or more symbols and may have a length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

[0239] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

[0240] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0241] A Bandwidth Part (BWP) (which may also be referred to as a fractional bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0242] The BWP may include a BWP for UL (UL BWP) and a BWP for DL ​​(DL BWP). One or more BWPs may be configured for a UE within one carrier.

[0243] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

[0244] The above-described structures of radio frames, subframes, slots, minislots, symbols, etc. are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, etc. may be variously changed.

[0245] 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.

[0246] The reference signal may also be abbreviated as Reference Signal (RS) and may be called a pilot depending on the applicable standard.

[0247] 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."

[0248] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0249] 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 therein or that the first element must precede the second element in some way.

[0250] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

[0251] 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.

[0252] 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.

[0253] 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."

[0254] 18 shows an example of the configuration of a vehicle 2001. As shown in Fig. 18, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right 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.

[0255] The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor.

[0256] 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.

[0257] 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 2027 provided in the vehicle. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0258] The signals from the various sensors 2021 to 2028 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.

[0259] 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 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 obtained from external devices via the communication module 2013, etc., to provide various types of multimedia information and multimedia services to the occupants of the vehicle 1.

[0260] 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 millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, 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 driving assistance functions or autonomous driving functions.

[0261] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from a driving unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, a microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028, which are provided in the vehicle 2001.

[0262] 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.

[0263] The communication module 2013 transmits, via wireless communication to an external device, a current signal from the current sensor that is input to the electronic control unit 2010. The communication module 2013 also transmits, via wireless communication to an external device, the rotation speed signals of the front and rear wheels acquired by a rotation speed sensor 2022, the air pressure signals of the front and rear wheels acquired by an air pressure sensor 2023, the vehicle speed signal acquired by a vehicle speed sensor 2024, the acceleration signal acquired by an acceleration sensor 2025, the accelerator pedal depression amount signal acquired by an accelerator pedal sensor 2029, the brake pedal depression amount signal acquired by a brake pedal sensor 2026, the shift lever operation signal acquired by a shift lever sensor 2027, and the detection signals for detecting obstacles, vehicles, pedestrians, etc. acquired by an object detection sensor 2028, all of which are input to the electronic control unit 2010.

[0264] 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. The communication module 2013 also stores the various information received from the 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, left and right front wheels 2007, left and right rear wheels 2008, axle 2009, sensors 2021 to 2028, and the like provided in the vehicle 2001.

[0265] 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.

[0266] (Additional Note) The above disclosure may be expressed as follows.

[0267] A first feature is a terminal comprising: a communication unit that communicates with a base station that forms a candidate cell to which the terminal is to move; and a control unit that generates a security key for the candidate cell based on a key generation parameter for each of the candidate cells, wherein the communication unit transmits key-related information related to the key generation parameter.

[0268] A second feature is the terminal according to the first feature, wherein the key-related information includes the key generation parameters used to generate the security key.

[0269] A third feature is the terminal according to the first or second feature, wherein the key-related information includes information indicating exhaustion of the key generation parameters allocated to the candidate cell.

[0270] A fourth feature is a base station including: a communication unit that communicates with a terminal; and a control unit that assumes that the terminal generates a security key for a candidate cell based on key generation parameters for each candidate cell to which the terminal is to move, wherein the communication unit receives key-related information related to the key generation parameters.

[0271] A fifth feature is a wireless communication system including a terminal and a base station, wherein the terminal includes a communication unit that communicates with a base station that forms a candidate cell to which the terminal is to move, and a control unit that generates a security key for the candidate cell based on a key generation parameter for each of the candidate cells, and the communication unit transmits key-related information related to the key generation parameter.

[0272] A sixth feature is a wireless communication method including: a step A of communicating with a base station that forms a candidate cell to which a terminal is to move; a step B of generating a security key for the candidate cell based on a key generation parameter for each of the candidate cells; and a step C of transmitting key-related information related to the key generation parameter.

[0273] 10 Wireless communication system 20 NG-RAN 100 gNB 110 Receiving unit 120 Transmitting unit 130 Control unit 200 UE 210 Radio signal transmitting / receiving unit 220 Amplifying unit 230 Modulation / demodulation unit 240 Control signal / reference signal processing unit 250 Encoding / decoding unit 260 Data transmitting / receiving unit 270 Control unit 1001 Processor 1002 Memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Left and right front wheels 2008 Left and right rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 RPM sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system section 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port

Claims

1. A terminal comprising: a communication unit that communicates with a base station that forms a candidate cell to which the terminal is to move; and a control unit that generates a security key for the candidate cell based on a key generation parameter for each of the candidate cells, wherein the communication unit transmits predicted information regarding the number of security keys to be allocated to the candidate cell.

2. The terminal of claim 1, wherein the prediction information includes information indicative of a predicted trajectory of a cell in which the terminal will move.

3. The terminal according to claim 1, wherein the prediction information includes information indicating the number of security keys to be allocated to the candidate cell.

4. A base station comprising: a communication unit that communicates with a terminal; and a control unit that assumes that the terminal generates a security key for the candidate cell based on key generation parameters for each candidate cell to which the terminal will move, wherein the control unit determines the number of security keys to be allocated to the candidate cell based on a predicted trajectory of the cell to which the terminal will move.

5. A wireless communication system comprising a terminal and a base station, wherein the terminal comprises: a communication unit that communicates with a base station that forms a candidate cell to which the terminal is to move; and a control unit that generates a security key for the candidate cell based on a key generation parameter for each of the candidate cells, and the communication unit transmits predicted information regarding the number of security keys to be allocated to the candidate cells.

6. A wireless communication method comprising: step A of communicating with a base station forming a candidate cell to which a terminal is to move; step B of generating a security key for the candidate cell based on a key generation parameter for each of the candidate cells; and step C of transmitting predicted information regarding the number of the security keys to be allocated to the candidate cells.

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