Terminal and communication method

Abstract

To clarify the behavior of a terminal after a Timing Advance (TA) value becomes invalid, such that the cell switching procedure can be performed appropriately in a system that supports conditional cell switching.SOLUTION: A terminal includes a transmission unit that transmits measurement information of Layer 1 and Layer 3 measured in one or more candidate cells to a base station, and a control unit that performs cell switching when a predetermined execution condition is met after transmitting the measurement information, and the control unit manages the validity of a TA value associated with each of the candidate cells, and the control unit performs a predetermined operation when the TA value becomes invalid.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In 3GPP (registered trademark) (3rd Generation Partnership Project) Rel-19, Conditional LTM, which supports RACH (Random Access Channel)-less LTM in addition to RACH-based LTM, is being discussed as a further improvement of LTM (Latency Triggered Mobility or Lower layer (L1 / L2)-Triggered Mobility).

[0003] In the Early TA (Timing Advance) acquisition procedure of the Conditional LTM procedure, the UE acquires the TA values ​​of multiple candidate cells in advance. In Rel-18 LTM, the validity of the TA values ​​was managed by the network side, but in Rel-19 conditional LTM, the validity of the TA values ​​must be guaranteed by the UE side.

[0004] To manage the validity of the TA value on the UE side, two methods are being discussed: one is to maintain a TA timer on the UE side, and the other is to determine that the TA value is valid if the change in the L1 measurement result is below a threshold. In other words, if the timer that manages the validity of the TA value in the UE expires or if the change in the L1 measurement result of the cell associated with the TA value exceeds a threshold, the TA value in the UE becomes invalid. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP TS 38.300 V18.2.0(2024-06) [Non-patent document 2] 3GPP TS 38.401 V18.2.0(2024-06) Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the past, the behavior of the UE when the TA value became invalid in conditional LTM was unclear, which led to the risk that the UE would not be able to properly switch cells / beams using conditional LTM. [Means for solving the problem]

[0007] The terminal in this embodiment includes a transmitter that transmits measurement information of Layer 1 and Layer 3 measured in one or more candidate cells to a base station, and a controller that executes cell switching when a predetermined execution condition is met after transmitting the measurement information, wherein the controller manages the validity of a TA value associated with each of the candidate cells, and the controller executes a predetermined operation when the TA value becomes invalid. [Effects of the Invention]

[0008] According to this embodiment, in a system that supports conditional cell switching, the operation of a terminal after a TA value becomes invalid is clarified, and the cell switching procedure can be executed appropriately. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a sequence diagram showing the operation of the wireless communication system in option 1. [Figure 3] FIG. 10 is a sequence diagram showing the operation of the wireless communication system in option 2. [Figure 4] FIG. 4 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the first embodiment. [Figure 5] FIG. 10 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the second embodiment. [Figure 6] FIG. 11 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the third embodiment. [Figure 7] FIG. 10 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the fourth embodiment. [Figure 8] FIG. 13 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the fifth embodiment. [Figure 9] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station according to the present embodiment. [Figure 10] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal according to the present embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station or a terminal according to the present embodiment. [Figure 12] 1 is a diagram illustrating an example of a configuration of a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] The wireless communication system of this embodiment operates using existing technology. The existing technology is, for example, a wireless communication technology based on a communication standard such as the 3GPP standard. The existing technology is, for example, NR (New Radio), but is not limited to existing NR. Unless otherwise specified, the term "NR" used in this specification has a broad meaning including NR (5G) and subsequent systems (for example, 6G).

[0012] In the present embodiment described below, terms used in existing LTE, such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel), are used. This is for convenience of description, and similar signals, functions, etc. may be called by other names. The above-mentioned terms in NR are referred to as SS, PSS, SSS, PBCH, PRACH, etc. without any particular distinction from LTE.

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

[0014] In this embodiment, when radio parameters etc. are "configured," it may mean that a predetermined value is pre-configured, or that radio parameters notified from the base station 10 or the terminal 20 are set.

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

[0016] The base station 10 is a communication device that provides one or more cells and performs wireless communication with the terminal 20. The physical resources of a wireless signal are defined in the time domain and the frequency domain. The time domain may be defined by the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols, and the frequency domain may be defined by the number of subcarriers or the number of resource blocks. The base station 10 transmits a synchronization signal and system information to the terminal 20. The synchronization signal is, for example, a PSS and an SSS. The system information is, for example, transmitted via a PBCH and is also referred to as broadcast information. The synchronization signal and system information may be referred to as an SSB (SS / PBCH block). As shown in FIG. 1 , the base station 10 transmits control signals or data to the terminal 20 in a downlink (DL) and receives control signals or data from the terminal 20 in an uplink (UL). Both the base station 10 and the terminal 20 are capable of transmitting and receiving signals by performing beamforming. Furthermore, both the base station 10 and the terminal 20 are capable of applying MIMO (Multiple Input Multiple Output) communication to the DL or UL. In addition, both the base station 10 and the terminal 20 may communicate via a secondary cell (SCell: Secondary Cell) and a primary cell (PCell: Primary Cell) using CA (Carrier Aggregation). Furthermore, the terminal 20 may communicate via a primary cell of the base station 10 and a primary secondary cell group cell (PSCell: Primary SCG Cell) of another base station 10 using DC (Dual Connectivity).

[0017] The base station 10 may be referred to as a RAN (Radio Access Network) node. The base station 10 is, for example, a gNodeB (gNB) in NR.

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

[0019] In the following description, " / " means "and / or" unless otherwise specified or unless a different meaning is clear from the context.

[0020] In the following, UE will be described as an example of a terminal, and gNB will be described as an example of a base station.

[0021] 3GPP Rel-18 introduced LTM (Lower layer (L1 / L2)-Triggered Mobility) as a technology to achieve low-latency, seamless communications for fast-moving UEs. LTM is a technology for fast cell switching from a source cell to a target cell, and Rel-18 specifies RACH-based LTM.

[0022] In 3GPP Rel-19, Conditional LTM is being discussed as a further improvement of LTM. Conditional LTM supports RACH-less LTM in addition to RACH-based LTM. In RACH-less LTM, the UE can connect to the target cell without transmitting a RACH preamble, further reducing the cell switching delay.

[0023] The following two options are being discussed for conditional LTM in Rel-19:

[0024] In Option 1, as shown in Figure 2, the network side determines potential candidate target cells / beams based on L1 (Layer 1) / L3 (Layer 3) measurement reporting.

[0025] In option 2, the UE determines potential candidate target cells / beams and reports them to the source cell, as shown in Figure 3.

[0026] Fig. 2 is a sequence diagram showing the operation of the wireless communication system in the above-mentioned Option 1. As shown in Fig. 2, in step S11, LTM preparation is performed. In step S12, Early TA acquisition is performed.

[0027] In step S13, the UE transmits an L1 / L3 measurement reporting to the Source gNB.

[0028] In step S14, the Source gNB determines potential candidate target cells / beams.

[0029] In step S15, the Source gNB transmits a Notification of potential candidate target cells / beams to the Target gNB 10-2. In the example of Figure 2, the Notification of potential candidate target cells / beams indicates targetConfigID#1, (UL)TCI state ID#1, targetConfigID#2, and (UL)TCIstate#2.

[0030] In step S16, the target gNB prepares radio resources (e.g., a dynamic grant) for the UE's first uplink transmission.

[0031] In step S17, the source gNB sends a notification of potential candidate target cells / beams (e.g., targetConfigID#1, (UL)TCI state ID#1, targetConfigID#2, (UL)TCIstate#2) to the UE.

[0032] In step S18, when an execution condition (for example, targetConfigID#1, (UL)TCI state ID#1) is satisfied, the UE 20 decides to switch to the target cell / beam. In step S19, the UE performs first uplink transmission to the target gNB. The execution condition is a condition for cell switching and may include a latency requirement.

[0033] FIG. 3 is a sequence diagram showing the operation of the wireless communication system in the above-mentioned option 2.

[0034] In step S21, LTM preparation is performed. In step S22, Early TA acquisition is performed. In step S23, the UE transmits L1 / L3 measurement reporting (potential candidate target cells / beams) to the Source gNB.

[0035] In step S24, the Source gNB determines potential candidate target cells / beams.

[0036] In step S25, the Source gNB sends a Notification of potential candidate target cells / beams (e.g., targetConfigID#1, (UL)TCI state ID#1, targetConfigID#2, (UL)TCIstate#2) to the Target gNB 10-2.

[0037] In step S26, the UE starts monitoring the execution condition.

[0038] In step S27, when an execution condition (for example, targetConfigID#1, (UL)TCI state ID#1) is satisfied, the UE decides to switch to the target cell / beam. In step S28, the UE performs first uplink transmission to the target gNB.

[0039] In the above-mentioned Early TA acquisition in step S12 in Fig. 2 and step S22 in Fig. 3, the UE acquires the TA values ​​of multiple candidate cells in advance. In the LTM of Rel-18, the validity of the TA value was managed on the network side, but in the conditional LTM of Rel-19, the validity of the TA value must be guaranteed on the UE side.

[0040] To manage the validity of the TA value on the UE side, two methods are being discussed: one is to maintain a TA timer on the UE side, and the other is to determine that the TA value is valid if the change in the L1 measurement result is below a threshold. In other words, if the timer that manages the validity of the TA value in the UE expires or if the change in the L1 measurement result of the cell associated with the TA value exceeds a threshold, the TA value in the UE becomes invalid.

[0041] However, in the past, the behavior of the UE when the TA value became invalid in conditional LTM was unclear, which led to the risk that the UE would not be able to properly switch cells / beams using conditional LTM.

[0042] According to this embodiment, the behavior of the UE after the TA value acquired by early TA acquisition in conditional LTM becomes invalid is clarified, and LTM can be executed appropriately.

[0043] In this embodiment, the conditional LTM includes subsequent conditional LTM. In the conditional LTM, RRC reconfiguration is required for each cell switch, but in the subsequent conditional LTM, after LTM is executed once, cell switch can be repeated between candidate cells without RRC reconfiguration.

[0044] In this embodiment, the conditional LTM may be referred to as a conditional cell switch, which is performed based on a predetermined execution condition after transmission of layer 1 and layer 3 measurement information.

[0045] In this embodiment, the cell may refer to at least one of a cell or a beam. In this embodiment, cell switching may refer to at least one of cell switching or beam switching.

[0046] Examples of the present embodiment will be described below. Each example may be implemented independently, or any combination of multiple examples may be implemented.

[0047] The embodiment shows the operation of the UE 20 when the TA value acquired by early TA acquisition in the conditional LTM procedure becomes invalid. Each TA value acquired in the early TA acquisition is associated with each candidate cell of the handover destination (target).

[0048] Example 1 According to the first embodiment, in the RACH-less conditional LTM, if the TA value held by the UE 20 for each candidate cell becomes invalid, the UE 20 may fall back to the RACH-based LTM, i.e., the RACH-based LTM may be triggered.

[0049] In order to fall back to RACH-based LTM, the network (gNB 10) may configure the UE 20 with dedicated RACH resources in advance for each candidate cell to fall back to RACH-based LTM.

[0050] If the TA value becomes invalid in the UE, the network may use RRC to signal or configure the UE 20 to fall back to RACH based LTM.

[0051] However, since RACH resources are limited, the network may not be able to prepare RACH resources for fallback to RACH-based LTM for each candidate cell. If RACH resources for fallback to RACH-based LTM are not configured in the UE 20, the UE 20 cannot fallback to RACH-based LTM implicitly (without explicit instruction, etc.). In such a case, the UE 20 may perform the operation of Example 2 or Example 3. If RACH resources for fallback to RACH-based LTM are configured in the UE 20, the configuration of the RACH resources in the UE 20 may mean that explicit fallback to RACH-based LTM is possible.

[0052] FIG. 4 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the first embodiment.

[0053] In step S101, LTM preparation is performed, which may include, for example, initial setting and parameter exchange for performing LTM.

[0054] In step S102, early TA acquisition is performed. Early TA acquisition is a procedure for early acquisition of a TA value. For example, UE 20 receives TA information including a TA value associated with each candidate cell from the network. For example, the TA value associated with each candidate cell includes the TA value of cell #3 managed by Target gNB 10-2. When UE 20 receives the TA information, it starts a TimeAlignmentTimer that manages the expiration date of the TA. When the TimeAlignmentTimer expires, UE 20 considers the TA information to be invalid and needs to acquire new TA information.

[0055] The UE 20 performs L1 (e.g., signal strength) measurements and L3 (e.g., delay) measurements of cells / beams (e.g., neighboring cells / beams). The L1 measurement result is, for example, at least one of RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), or SINR (Signal to Interference plus Noise Ratio). The L3 measurement result is, for example, at least one of delay, jitter, or packet loss.

[0056] Based on the measurement results, the UE 20 identifies potential candidate target cells / beams that are candidates for a target (target) cell / beam to switch to. The potential candidate target cells / beams are, for example, cells / beams with better communication quality than the current cell / beam and / or cells / beams that may be capable of communication with low latency.

[0057] In step S103, the UE 20 transmits an L1 / L3 measurement reporting to the Source gNB 10-1. The L1 / L3 measurement reporting includes L1 and L3 measurement results of potential candidate target cells / beams. The cell IDs / beam IDs of the potential candidate target cells / beams may be included in the L1 / L3 measurement reporting, or may be included in a notification separate from the L1 / L3 measurement reporting.

[0058] In step S104, Source gNB 10-1 transmits a Notification of potential candidate target cells / beams to Target gNB 10-2. In the example of Fig. 4, the potential candidate target cells / beams indicate targetConfigID#1, (UL)TCI state ID#1, targetConfigID#2, and (UL)TCIstate#2.

[0059] In step S105, the Target gNB 10-2 prepares radio resources (e.g., a dynamic grant) for the first uplink transmission (first UL transmission) to the target (target) cell / beam by the UE 20. This is a process in which the Target gNB 10-2 prepares radio resources for communication with the UE 20. The dynamic grant is a radio resource that is dynamically allocated for data transmission.

[0060] In step S106, the TA value of cell #3 becomes invalid in UE 20. For example, TimeAlignmentTimer, which is a timer associated with the TA of cell #3, expires, and UE 20 determines that the TA value of cell #3 has become invalid. As another example of when the TA value becomes invalid, UE 20 determines that the TA value of cell #3 has become invalid when a change in the measurement result of L1 of cell #3 exceeds a predetermined threshold.

[0061] In step S107, the UE 20 may fall back to the RACH-based LTM, and the RACH-based LTM may be performed between the UE 20 and the Target gNB 102. The UE 20 may perform the fallback to the RACH-based LTM when the TA value of cell #3 becomes invalid. As another example, the network (gNB 10) may instruct the UE 20 to fall back to the RACH-based LTM.

[0062] Example 2 According to Example 2, when the TA value that UE 20 holds for each candidate cell becomes invalid, UE 20 may send a notification to the network (Source gNB 10-1) indicating that the TA value has become invalid.

[0063] The notification may indicate for each cell (candidate cell) associated with the TA value that the TA value has become invalid.

[0064] The network may transmit a PDCCH ordered RACH to the UE 20 as an instruction to perform a RACH procedure in the candidate cell for which the TA value has become invalid. After the UE 20 transmits a RACH preamble to the Target gNB 10-2 (Target DU (Distributed Unit)), the Target gNB 10-2 may calculate a new TA value and transmit the new TA value to the Source gNB 10-1 (Source DU) via a CU (Central Unit). The Source gNB 10-1 (Source DU) may then transmit the new TA value to the UE 20 using a new MAC CE. These procedures may be performed for each candidate cell.

[0065] Fig. 5 is a sequence diagram showing an example of the operation of the wireless communication system in Example 2. The operations of steps S201 to S206 in Fig. 5 are the same as the operations of steps S101 to S106 in Fig. 4, respectively.

[0066] In step S207, the UE 20 sends a notification to the Source gNB 10-1 indicating that the TA value associated with cell #3 has become invalid.

[0067] In step S208, a TA acquisition procedure is performed between UE 20, Source gNB 10-1 and Target gNB 10-2, and in step S209, UE 20 acquires a new TA value associated with cell #3 from Source gNB 10-1 via a new MAC CE.

[0068] In step S210, the UE 20 starts monitoring the execution condition.

[0069] In step S211, if the execution condition is met, the UE 20 decides to execute switching to the target cell / beam.

[0070] In step S212, the UE 20 performs a first uplink transmission to the Target gNB 10-2.

[0071] Example 3 According to the third embodiment, when the TA value held by the UE 20 for each candidate cell becomes invalid, the UE 20 may exclude the candidate cell / beam associated with the invalid TA value from the cells / beams targeted for monitoring the execution condition. That is, the targets for monitoring the execution condition are the candidate cells / beams associated with the valid TA value.

[0072] Fig. 6 is a sequence diagram showing an example of the operation of the wireless communication system in Example 3. The operations of steps S301 to S306 in Fig. 6 are the same as the operations of steps S101 to S106 in Fig. 4, respectively.

[0073] In step S307, the UE 20 excludes cell #3, which is associated with the TA value that was invalidated in step S306, from the targets of execution condition monitoring.

[0074] In step S308, if the execution condition is met, the UE 20 decides to execute switching to the target cell / beam.

[0075] In step S309, the UE 20 performs a first uplink transmission to the Target gNB 10-2.

[0076] Example 4 According to the fourth embodiment, if the TA value that the UE 20 holds for each candidate cell becomes invalid, the UE 20 may request the network to fall back to NW (Network) controlled LTM (i.e., Rel-18 LTM).

[0077] FIG. 7 is a sequence diagram illustrating an example of an operation of the wireless communication system according to the fourth embodiment.

[0078] The operations in steps S401 to S406 in FIG. 7 are the same as the operations in steps S101 to S106 in FIG. 4, respectively.

[0079] In step S407, the UE 20 sends a request to the Source gNB 10-1 to fall back to NW controlled LTM (i.e., Rel-18 LTM).

[0080] NW controlled LTM is a method in which the network proactively controls UE mobility. In NW controlled LTM, the network determines the optimal cell for the UE, taking into account the UE's surrounding environment and the overall network situation, and then transmits information about the target cell and conditions for performing the switch (e.g., delay threshold, throughput threshold, etc.) to the UE. The UE performs cell switching based on the information received from the network.

[0081] In step S408, a NW controlled LTM procedure is performed between the UE 20, the Source gNB 10-1 and the Target gNB 10-2.

[0082] Example 5 According to Example 5, if the TA value that the UE 20 holds for each candidate cell becomes invalid, the UE 20 may notify the network that the TA value has become invalid, and the network may trigger a fallback to NW controlled LTM (i.e., Rel-18 LTM).

[0083] Fig. 8 is a sequence diagram showing an example of the operation of the wireless communication system in the embodiment 5. The operations of steps S501 to S506 in Fig. 8 are the same as the operations of steps S101 to S106 in Fig. 4, respectively.

[0084] In step S507, the UE 20 notifies the Source gNB 10-1 that the TA value associated with cell #3 is invalid.

[0085] In step S508, Source gNB 10-1 triggers UE 20 to fall back to NW-controlled LTM, and in step S509, Source gNB 10-1 triggers Target gNB 10-2 to fall back to NW-controlled LTM.

[0086] In step S510, a NW controlled LTM procedure is performed between the UE 20, the Source gNB 10-1 and the Target gNB 10-2.

[0087] Example 6 According to the sixth embodiment, the UE 20 may determine that the TA value associated with the candidate cell is invalid as an LTM failure. In this case, "invalid TA value" may be set as the cause of the LTM failure.

[0088] As described above, according to the above embodiment, the operation after the TA value acquired by early TA acquisition in conditional LTM becomes invalid is clarified, and LTM can be executed appropriately.

[0089] (Device configuration) Next, a description will be given of an example of the functional configuration of the base station 10 and the terminal 20 that execute the processes and operations described above. The base station 10 and the terminal 20 include functions for implementing the above-described embodiments. However, the base station 10 and the terminal 20 may each include only a part of the functions of the embodiments.

[0090] <Base station> Fig. 9 is a diagram showing an example of the functional configuration of the base station 10 in this embodiment. As shown in Fig. 9, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Fig. 9 is merely an example. The functional divisions and names of the functional units may be any names as long as they can execute the operations according to this embodiment.

[0091] The transmitter 110 includes a function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The transmitter 110 also transmits setting information, instructions, notifications, etc. related to a low-power wake-up signal to the terminal 20. The transmitter 110 also transmits notifications related to switching of monitoring operations to the terminal. The receiver 120 includes a function of receiving various signals transmitted from the terminal 20 and acquiring, for example, information of higher layers from the received signals. The transmitter 110 also has a function of transmitting PSS, SSS, PBCH, DL / UL control signals, etc. to the terminal 20. The receiver 120 also receives inter-network node messages from other network nodes.

[0092] The setting unit 130 stores preset setting information and various setting information to be transmitted to the terminal 20. The content of the setting information is, for example, information related to measurements of low-power signals.

[0093] As described in the embodiments, the control unit 140 controls settings, instructions, and notifications related to low-power wake-up signals, etc. A functional unit related to signal transmission in the control unit 140 may be included in the transmitting unit 110, and a functional unit related to signal reception in the control unit 140 may be included in the receiving unit 120.

[0094] <terminal> Fig. 10 is a diagram showing an example of the functional configuration of the terminal 20 in this embodiment. As shown in Fig. 10, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 10 is merely an example. As long as the operations according to this embodiment can be performed, the names of the functional divisions and functional units may be any. The transmitting unit 210 and the receiving unit 220 may be collectively referred to as a communication unit.

[0095] The transmitter 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The transmitter 210 also transmits capability information related to the low-power wake-up signal to the base station 10. The receiver 220 receives various signals wirelessly and acquires higher layer signals from the received physical layer signals. The receiver 220 also has a function of receiving PSS, SSS, PBCH, DL / UL / SL control signals, and the like transmitted from the base station 10. The receiver 220 also receives paging notification information and configuration information, instructions, and notifications related to the low-power wake-up signal from the base station 10. For example, the receiver 220 receives the low-power wake-up signal from the base station 10. The configuration unit 230 stores various configuration information received by the receiver 220 from the base station 10. The configuration unit 230 also stores pre-configured configuration information. The configuration information includes, for example, information related to measurements of the low-power signal.

[0096] As described in the embodiments, the control unit 240 controls the settings, instructions, and notifications related to the low-power wake-up signal. The function unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and the function unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0097] (Hardware configuration) The block diagrams (FIGS. 9 and 10) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or may be realized using two or more devices that are physically or logically separated and connected directly or indirectly (for example, by wire, wirelessly, etc.). The functional block may be realized by combining software with the one device or the multiple devices.

[0098] 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 these functions are implemented.

[0099] For example, the base station 10, the terminal 20, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 11 is a diagram illustrating an example of the hardware configuration of the base station 10 and the terminal 20 according to an embodiment of the present disclosure. The base station 10 and the terminal 20 described above may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0100] In the following description, the term "apparatus" can be read as a circuit, a device, a unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0101] Each function in the base station 10 and the terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001, the memory device 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls at least one of reading and writing data in the memory device 1002 and the auxiliary memory device 1003.

[0102] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0103] Furthermore, the processor 1001 reads programs (program codes), software modules, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes in accordance with the programs. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 140 of the base station 10 shown in FIG. 9 may be implemented by a control program stored in the storage device 1002 and executed by the processor 1001. Furthermore, for example, the control unit 240 of the terminal 20 shown in FIG. 10 may be implemented by a control program stored in the storage device 1002 and executed by the processor 1001. While the above-described various processes have been described as being executed by one processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0104] The storage device 1002 is a computer-readable recording medium and may be configured, for example, by at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The storage device 1002 may also be called a register, a cache, a main memory, etc. The storage device 1002 can store executable programs (program codes), software modules, etc. for implementing a communication method according to an embodiment of the present disclosure.

[0105] The secondary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium including at least one of the storage device 1002 and the secondary storage device 1003.

[0106] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, a transmission / reception antenna, an amplifier unit, a transmission / reception unit, a transmission path interface, etc. may be realized by the communication device 1004. The transmission / reception unit may be implemented as a transmission unit and a reception unit that are physically or logically separated.

[0107] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0108] Furthermore, each device such as the processor 1001 and the storage device 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0109] Furthermore, base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, processor 1001 may be implemented using at least one of these pieces of hardware.

[0110] Fig. 12 shows an example configuration of a vehicle 2001. As shown in Fig. 12, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in the present disclosure may be applied to a communication device mounted on the vehicle 2001, and may be applied to the communication module 2013, for example.

[0111] The drive unit 2002 is configured, for example, by an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle), and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel operated by the user.

[0112] The electronic control unit 2010 is composed of a microprocessor 2031, a memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0113] The signals from the various sensors 2021 to 2029 include a current signal from a current sensor 2021 that senses the current of the motor, a front or rear wheel rotation speed signal obtained by a rotation speed sensor 2022, a front or rear wheel air pressure signal 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.

[0114] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from external devices via the communication module 2013 or the like to provide various types of multimedia information and multimedia services to the occupants of the vehicle 2001. The information service unit 2012 may include input devices (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, a touch panel, etc.) that accept input from the outside, and may also include output devices (e.g., a display, a speaker, an LED lamp, a touch panel, etc.) that output information to the outside.

[0115] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driver's driving burden, such as a millimeter-wave radar, a LiDAR (Light Detection and Ranging), a camera, a positioning locator (e.g., GNSS, etc.), map information (e.g., high-definition (HD) map, autonomous vehicle (AV) map, etc.), a gyro system (e.g., an IMU (Inertial Measurement Unit), an INS (Inertial Navigation System), etc.), an AI (Artificial Intelligence) chip, and an AI processor, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize the driving assistance function or the autonomous driving function.

[0116] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 29, which are provided in the vehicle 2001.

[0117] 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.

[0118] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0119] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from external devices in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021 to 2029, etc. provided in the vehicle 2001.

[0120] (Configuration of this embodiment) (Additional note 1) A terminal comprising: a transmitter that transmits measurement information of Layer 1 and Layer 3 measured in one or more candidate cells to a base station; and a controller that performs cell switching when a predetermined execution condition is met after the measurement information is transmitted, wherein the controller manages the validity of a Timing Advance (TA) value associated with each of the candidate cells, and the controller performs a predetermined operation when the TA value becomes invalid.

[0121] (Additional note 2) The terminal according to claim 1, wherein the predetermined operation is an operation of falling back to a cell switching procedure involving a random access procedure.

[0122] (Additional note 3) The terminal according to claim 1, wherein the predetermined operation is an operation of transmitting a notification to the base station indicating that the TA value has become invalid.

[0123] (Additional note 4) The terminal according to Supplementary Item 1, wherein the predetermined operation is an operation of excluding a candidate cell associated with the invalid TA value from targets for monitoring the predetermined execution condition.

[0124] (Additional note 5) The terminal according to claim 1, wherein the predetermined operation is an operation of requesting the base station to fall back to a cell switching procedure based on network control.

[0125] (Additional note 6) 1. A communication method executed by a terminal, the communication method comprising: a step of managing the validity of a Timing Advance (TA) value associated with each of one or more candidate cells; a step of transmitting measurement information of Layer 1 and Layer 3 measured in the candidate cells to a base station; a step of performing cell switching when a predetermined execution condition is met after transmitting the measurement information; and a step of falling back to a cell switching procedure involving a random access procedure when the TA value becomes invalid or transmitting a notification indicating that the TA value has become invalid to the base station.

[0126] Any of the above configurations clarifies the operation of a terminal after a TA value becomes invalid in a system that supports conditional cell switching, and enables the cell switching procedure to be performed appropriately.

[0127] (Supplementary explanation of the embodiment) Although the present embodiment has been described above, the disclosed invention is not limited to such an embodiment, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention; matters described in two or more items may be used in combination as needed, and matters described in one item may apply to matters described in another item (unless inconsistent). The boundaries between functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of the processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, the base station 10 and terminal 20 have been described using functional block diagrams. However, such devices may be implemented using hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to this embodiment and the software operated by the processor of the terminal 20 according to this embodiment may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server or any other suitable storage medium.

[0128] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling), broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0129] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (New Radio), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark), IEEE 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), or other appropriate 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 and 5G) may also be applied.

[0130] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described herein may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order and are not limited to the particular order presented.

[0131] In this specification, a specific operation that is described as being performed by the base station 10 may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station 10, it is clear that various operations performed for communication with the terminal 20 may be performed by at least one of the base station 10 and another network node other than the base station 10 (such as, but not limited to, an MME or an S-GW). Although the above example illustrates a case where there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (such as an MME and an S-GW).

[0132] The information or signals described in the present disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0133] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0134] In the present disclosure, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0135] 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.

[0136] 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.

[0137] 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.

[0138] Note that terms explained in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0139] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0140] 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.

[0141] 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.

[0142] In the present disclosure, terms such as "base station (BS)," "radio base station," "base station device," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0143] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication service by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or base station subsystem that provides communication service within this coverage.

[0144] 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.

[0145] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0146] 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.

[0147] At least one of the base station and the mobile station may be referred to as a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, the mobile object itself, etc. The mobile object refers to a movable object, and may move at any speed. Naturally, this also includes cases where the mobile object is stationary. Examples of the mobile object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The mobile object may also be a mobile object that moves autonomously based on an operational command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0148] Furthermore, a base station in the present disclosure may be read as a user terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between a plurality of terminals 20 (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0149] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station may be configured to have the functions of the user terminal described above.

[0150] 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.

[0151] 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 at least one of one or more wires, cables, and 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.

[0152] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0153] 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."

[0154] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0155] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0156] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0157] A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0158] Numerology may be communication parameters that apply to at least one of transmission and reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

[0159] A slot may be composed of one or more symbols (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol) in the time domain. A slot may be a time unit based on numerology.

[0160] 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.

[0161] 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.

[0162] For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called 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 (for example, 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc. instead of a subframe.

[0163] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate wireless resources (such as frequency bandwidth and transmission power that can be used by each terminal 20) to each terminal 20 in TTI units. Note that the definition of TTI is not limited to this.

[0164] 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.

[0165] 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. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0166] 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.

[0167] 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.

[0168] A resource block (RB) is a resource allocation unit in the time domain and 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 also be determined based on numerology.

[0169] 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.

[0170] 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, or the like.

[0171] 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.

[0172] 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 the BWP.

[0173] 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.

[0174] 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."

[0175] 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 changed in various ways.

[0176] 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.

[0177] 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."

[0178] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, notification of predetermined information (e.g., notification that "X is true") is not limited to being done explicitly, but may be done implicitly (e.g., by not notifying the predetermined information).

[0179] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure. [Explanation of symbols]

[0180] 10 base station 110 Transmitter 120 Receiver 130 Setting section 140 Control Unit 20 terminals 210 Transmitter 220 Receiving unit 230 Setting Section 240 Control Unit 1001 processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication equipment 1005 Input Device 1006 Output Device 2001 Vehicle 2002 Drive unit 2003 Steering Section 2004 accelerator pedal 2005 brake pedal 2006 Shift Lever 2007 front wheel 2008 rear wheel 2009 Axle 2010 Electronic Control Unit 2012 Information Services Department 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 Systems Department 2031 microprocessor 2032 memory (ROM, RAM) 2033 Communication port (IO port)

Claims

1. a transmitter configured to transmit Layer 1 and Layer 3 measurement information measured in one or more candidate cells to a base station; a control unit that executes cell switching when a predetermined execution condition is satisfied after transmitting the measurement information; The control unit manages the validity of a Timing Advance (TA) value associated with each of the candidate cells; The control unit executes a predetermined operation when the TA value becomes invalid.

2. The terminal according to claim 1 , wherein the predetermined operation is an operation of falling back to a cell switching procedure involving a random access procedure.

3. The terminal according to claim 1 , wherein the predetermined action is an action of transmitting a notification indicating that the TA value has become invalid to the base station.

4. The terminal according to claim 1 , wherein the predetermined operation is an operation of excluding candidate cells associated with the invalid TA value from targets for monitoring the predetermined execution condition.

5. The terminal according to claim 1 , wherein the predetermined action is an action of requesting the base station to perform a fallback to a network-controlled cell switching procedure.

6. A communication method performed by a terminal, comprising: managing the validity of a Timing Advance (TA) value associated with each of the one or more candidate cells; transmitting layer 1 and layer 3 measurement information measured in the candidate cell to a base station; After transmitting the measurement information, when a predetermined execution condition is satisfied, performing cell switching; When the TA value becomes invalid, falling back to a cell switching procedure involving a random access procedure or sending a notification to the base station indicating that the TA value has become invalid.

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