Terminal and communication method

Abstract

To report information relating to the mobility performed by a terminal communicating with multiple cells to a network.SOLUTION: A terminal includes a transceiver unit that communicates with a base station via multiple cells, and a control unit that executes mobility in each of the multiple cells when predetermined execution conditions are met, and the transceiver unit transmits information related to the mobility of at least one of the multiple cells to the base station on the basis of detection of failure or success of the executed mobility.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] 3GPP (registered trademark) (3rd Generation Partnership Project) Release 20 (hereinafter referred to as Rel-20) is considering the expansion of the Self-Organizing Networks (SON) function. The SON function includes the Mobility Robustness Optimization (MRO) function, which is a technology for optimizing mobility-related functions and operations (handover and cell selection quality). Strengthening of MRO in Lower-layer Triggered Mobility (LTM), which was introduced in Rel-19, is being discussed. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.300 V18.5.0(2025-03) [Non-patent document 2] 3GPP TS 38.401 V18.5.0(2025-03) Summary of the Invention [Problem to be solved by the invention]

[0004] When a UE (User Equipment) communicating using multiple cells through dual connectivity performs mobility (e.g., LTM), it may be possible that LTM in an SCG (Secondary Cell Group) (e.g., conditional LTM involving an SCG change) is performed simultaneously with LTM in an MCG (Master Cell Group). In such a case, for example, when LTM in an SCG fails or succeeds, it is unclear what information the UE should report to the network. Therefore, there is a risk that the network side will not be able to optimize mobility. [Means for solving the problem]

[0005] In this embodiment, the terminal comprises a transceiver unit that communicates with a base station via multiple cells, and a control unit that executes mobility in each of the multiple cells when specified execution conditions are met, and the transceiver unit transmits information related to the mobility of at least one of the multiple cells to the base station based on detection of failure or success of the executed mobility. [Effects of the Invention]

[0006] According to this embodiment, information related to mobility performed by a terminal communicating using multiple cells can be reported to the network. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a wireless communication system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a sequence diagram showing an example of an operation procedure including transmission of an RLF report / handover failure report in the wireless communication system of the present embodiment. [Figure 3] FIG. 2 is a sequence diagram showing an example of an operation procedure including SHR transmission in the wireless communication system of the present embodiment. [Figure 4]10 is a sequence diagram showing an example of an operation procedure including transmission of SCG failure information in the wireless communication system of the present embodiment. FIG. [Figure 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station according to the present embodiment. [Figure 6] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal according to the present embodiment. [Figure 7] FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station or a terminal according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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.

[0009] The operation of the wireless communication system of the present embodiment may use an existing technology as appropriate, such as, but not limited to, the existing NR (New Radio) or LTE.

[0010] In the present embodiment described below, terms used in existing technologies, 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 correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, etc. However, even signals used in NR are not necessarily designated as "NR-".

[0011] 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.).

[0012] In this embodiment, "configuring" radio parameters etc. may mean that predetermined values ​​are pre-configured, or that radio parameters notified from a base station or a terminal are set.

[0013] (System Configuration) Fig. 1 is a diagram for explaining a wireless communication system in this embodiment. As shown in Fig. 1, the wireless communication system in this embodiment includes a base station (gNB) 10 and a terminal (UE (User Equipment)) 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.

[0014] The base station 10 is a communication device that provides one or more cells and performs wireless communication with the terminal 20. The physical resources of a wireless signal are defined in the time domain and the frequency domain, and the time domain may be defined by the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols, and the frequency domain may be defined by the number of subcarriers or the number of resource blocks. A TTI (Transmission Time Interval) in the time domain may be a slot, or a TTI may be a subframe.

[0015] The base station 10 transmits a synchronization signal and system information to the terminal 20. The synchronization signal is, for example, NR-PSS and NR-SSS. The system information is transmitted, for example, via the NR-PBCH and is also referred to as broadcast information. The synchronization signal and system information may be referred to as an SSB (SS / PBCH block). As shown in FIG. 1 , the base station 10 transmits control signals or data to the terminal 20 via DL (Downlink) and receives control signals or data from the terminal 20 via UL (Uplink). Both the base station 10 and the terminal 20 are capable of transmitting and receiving signals by performing beamforming. Both the base station 10 and the terminal 20 are capable of applying MIMO (Multiple Input Multiple Output) communication to DL or UL. Both the base station 10 and the terminal 20 may communicate via a secondary cell (SCell) and a primary cell (PCell) using Carrier Aggregation (CA). Furthermore, the terminal 20 may perform communication via a primary cell of the base station 10 and a primary secondary cell group cell (PSCell: Primary SCG Cell) of another base station 10 using DC (Dual Connectivity).

[0016] The terminal 20 is a communication device equipped with a wireless communication function, such as a smartphone, a mobile phone, a tablet, a wearable terminal, or an M2M (Machine-to-Machine) communication module. As shown in Fig. 1, the terminal 20 receives control signals or data from the base station 10 via DL and transmits control signals or data to the base station 10 via UL, thereby utilizing various communication services provided by the wireless communication system. The terminal 20 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.

[0017] In the wireless communication system according to this embodiment, the terminal 20 supports Dual Connectivity. The terminal 20 communicates with the base station 10 via a plurality of cells, for example, a Master Cell Group (MCG) and a Secondary Cell Group (SCG).

[0018] The wireless communication system according to this embodiment supports LTM. LTM is a mobility procedure triggered when conditions of L1 (Layer 1) or L3 are satisfied, and it may be Conditional LTM. Conditional LTM is executed only when a predetermined execution condition is satisfied, and may be applied to at least one of MCG (for example, change of PCell (handover)) and SCG (for example, change or addition of PSCell).

[0019] Since LTM enables low-latency and rapid response compared to control by a higher layer (such as the RRC layer), it is effective in improving mobility stability and throughput, particularly in a high-mobility environment or a high-density network environment.

[0020] The trigger in LTM is configured by conditions such as when a quality metric such as received power (RSRP) or signal-to-interference-plus-noise ratio (SINR) for a specific reference signal (CSI-RS, SSB, etc.) exceeds or falls below a predetermined threshold. These conditions are defined as LTM events (for example, eventLTM2, eventLTM3, eventLTM4, eventLTM5) and are determined by the UE 20.

[0021] The LTM events (eventLTM2, eventLTM3, eventLTM4, eventLTM5) are defined as follows.

[0022] <eventLTM2 (when the beam quality of the serving cell deteriorates from a predetermined threshold)> UE 20 determines that the entry condition of eventLTM2 is satisfied when the following conditions are met, and determines that the leaving condition is satisfied when other conditions are met.

[0023] · Entry condition: Ms + Hys < Thresh · Leaving condition: Ms - Hys > Thresh Here, Ms is the measurement quantity of the beam of the serving cell measured based on the SS / PBCH block or CSI-RS, and it is a value without considering the offset. The beam corresponds to the RS set in the indicated TCI state or the RS having a QCL relationship with that RS. [[ID=!4]]

[0024] Hys is the hysteresis parameter set for LTMeventLTM2.

[0025] Thresh is the threshold parameter for the same event.

[0026] Ms is expressed in dBm for RSRP and in dB for SINR, and Hys and Thresh are expressed in dB units. <!

[0027] <eventLTM3 (when the beam of the candidate cell is of better quality than the beam of the serving cell)> UE 20 determines that the entry condition of eventLTM3 is satisfied when the following conditions are met, and determines that the leaving condition is satisfied when other conditions are met.

[0028] · Entry condition: Mn + Obn - Hys > Ms + Obs + Off · Leaving condition: Mn + Obn + Hys < Ms + Obs + Off Here, Mn is the measurement quantity of the beam of the LTM candidate cell measured based on the SS / PBCH block or CSI-RS, and the offset is not included.

[0029] Obn is the offset of the beam applied to the LTM candidate cell.

[0030] Ms is the measurement value of the current beam in the serving cell.

[0031] Obs is the offset with respect to the beam of the serving cell.

[0032] Off is the additional offset for eventLTM3.

[0033] Mn and Ms are expressed in dBm for RSRP and in dB for SINR, and all other values are expressed in dB units.

[0034] <eventLTM4 (when the beam of the candidate cell exceeds the absolute threshold)> UE 20 determines that the entry condition of eventLTM4 is satisfied when the following conditions are met, and the leaving condition is satisfied when another condition is met.

[0035] · Entry condition: Mn + Obn - Hys > Thresh · Leaving condition: Mn + Obn + Hys < Thresh Here, Mn is the beam measurement value of the LTM candidate cell, based on the SS / PBCH block or CSI-RS, without considering the offset.

[0036] Obn is the offset with respect to the beam of the LTM candidate cell.

[0037] Hys is the hysteresis parameter for the event.

[0038] Thresh is the absolute threshold set for eventLTM4.

[0039] Mn is represented in dBm (for RSRP) or dB (for SINR), Obn and Hys are in dB units, and Thresh is represented in the same unit as Mn.

[0040] <eventLTM5 (when the beam of the serving cell is worse than threshold 1 and the beam of the candidate cell is better than threshold 2)> UE 20 determines that the entry condition is satisfied when both of the following conditions are met, and determines that the leaving condition is satisfied when at least one of the conditions is met.

[0041] · Entry condition 1: Ms + Hys < Thresh1 · Entry condition 2: Mn + Obn - Hys > Thresh2 · Leaving condition 1: Ms - Hys > Thresh1 · Leaving condition 2: Mn + Obn + Hys < Thresh2 Here, Ms and Mn are the beam measurement quantities of the serving cell and the candidate cell respectively, measured based on the SS / PBCH block or CSI-RS, and do not include offsets.

[0042] Obn is the offset for the beam of the candidate cell.

[0043] Hys is the hysteresis parameter for LTM5.

[0044] Thresh1 and Thresh2 are the thresholds set for the serving cell and the candidate cell respectively.

[0045] Ms and Mn are represented in dBm (RSRP) or dB (SINR), and the other parameters are represented in dB units.

[0046] In this embodiment, the L3 execution condition, which is a trigger condition for starting the execution of mobility processing based on LTM, may be, for example, one or more of the following (1) to (6).

[0047] (1) CondEvent A3 This event occurs when the radio quality of the conditional reconfiguration candidate becomes better than that of the current primary cell (PCell) or secondary primary cell (PSCell) by a predetermined offset.

[0048] (2) CondEvent A4 This event occurs when the radio quality of the conditional reconfiguration candidate exceeds an absolute threshold. If the candidate cell is configured as a PSCell, the current PSCell may also be evaluated. This condition applies especially to conditional handover (CHO) using a candidate secondary cell group (SCG).

[0049] (3) CondEvent A5 This event occurs when the radio quality of the PCell or PSCell falls below a first absolute threshold (absolute threshold1) and the radio quality of the conditional reconfiguration candidate exceeds a second absolute threshold (absolute threshold2).

[0050] (4) CondEvent D1 This event occurs when the distance between the user equipment (UE) and reference location 1 (referenceLocation1) exceeds a predetermined threshold (distanceThreshFromReference1) and the distance between the UE and the conditional reconfiguration candidate reference location 2 (referenceLocation2) falls below another predetermined threshold (distanceThreshFromReference2).

[0051] (5) CondEvent D2 This event occurs when the distance between the UE and the moving reference location (movingReferenceLocation) of the Serving Cell, determined based on the satellite ephemeris information and epoch time broadcast in SIB19, exceeds a predetermined threshold (distanceThreshFromReference1), and the distance between the UE and the moving reference location provided by the MeasObjectNR associated with the conditional reconfiguration candidate falls below another predetermined threshold (distanceThreshFromReference2).

[0052] (6) CondEvent T1 This event occurs when the time measured at the UE exceeds a predetermined threshold (t1-Threshold) and is less than t1-Threshold plus a predetermined duration.

[0053] When a UE communicating using multiple cells through dual connectivity performs mobility (e.g., LTM), LTM in an SCG (e.g., conditional LTM involving an SCG change) may be performed simultaneously with LTM in an MCG. Conventionally, in such a case, for example, when LTM in an SCG fails or succeeds, it has not been specified what information the UE should report to the network. Therefore, the network may not be able to optimize mobility.

[0054] According to this embodiment, when a UE 20 communicating using multiple cells performs mobility, the UE 20 can transmit information related to mobility in at least one of the multiple cells to the gNB 10.

[0055] In this embodiment, a cell (for example, a PCell or a PSCell) may be read as a cell group (for example, an MCG or an SCG).

[0056] The LTM in this embodiment is an example of mobility including handover, cell switching, cell change, and cell addition. The LTM may be a conditional LTM.

[0057] An example of the operation of the wireless communication system according to this embodiment will be described below. One or more operation examples included in this embodiment may be executed independently or in any combination.

[0058] (Present embodiment) According to this embodiment, a UE 20 that communicates using multiple cells performs mobility when a predetermined execution condition is met, and based on detection of failure or success of the performed mobility, transmits information (mobility-related information) related to the mobility of at least one of the multiple cells to a gNB 10.

[0059] For example, a UE 20 communicating using multiple cells may send a Radio Link Failure (RLF) report to a gNB 10 when LTM in at least one of an MCG or an SCG fails.

[0060] For example, a UE 20 communicating using multiple cells may transmit an SCG Failure Information message to a gNB 10 when an LTM in an SCG fails.

[0061] For example, a UE 20 communicating using multiple cells transmits a successful handover report (SHR) to a gNB 10 when LTM in at least one of an MCG or an SCG is successful.

[0062] RLF reports and SCG failure information are examples of mobility-related information based on the detection of mobility-related failures. SHR is an example of mobility-related information based on the detection of mobility-related successes.

[0063] In this embodiment, the LTM or conditional LTM in the MCG is referred to as LTM or conditional LTM.

[0064] In this embodiment, LTM or conditional LTM in SCG is referred to as SCG LTM or SCG conditional LTM.

[0065] The mobility-related information may include at least one of the following information elements:

[0066] 1) FirstFulfilledConfig: Information about the configuration in which the execution conditions for conditional LTM in the MCG or conditional LTM in the SCG (i.e., change or addition of a PSCell) are first fulfilled 2) Time Between Fulfillment: Information indicating the time interval between the time when the execution condition for the conditional LTM in the MCG is satisfied and the time when the execution condition for the conditional LTM (i.e., change or addition of a PSCell) in the SCG is satisfied. TimeBetweenFulfillment may include a timestamp indicating the time when the execution conditions for the conditional LTM in the MCG and SCG were met.

[0067] 3) TimeBetweenLastFulfillmentAndEvent: Information indicating at least one of the time intervals from 3-1) to 3-4) below. 3-1) From the time when the execution condition for conditional LTM in MCG is met until RLF is detected or handover failure occurs For example, if an RRC connection cannot be established with the target cell before the expiration of T304, which is a timer specified in the RRC Reconfiguration message, it is considered a handover failure.

[0068] 3-2) From the moment the execution condition for conditional LTM in the SCG is met until SCG failure occurs 3-3) From the moment the execution condition for conditional LTM in MCG is met until LTM execution starts after handover is successful 3-4) From the moment the condition for conditional LTM execution in SCG is met to the moment LTM execution in SCG begins 4) Identification and quality information of MCG (PCell) and SCG (PSCell): Information indicating at least one of the following 4-1) to 4-4). 4-1) Beam IDs (SSB index, CSI-RS index) on the PCell and PSCell sides and L1 / L3 quality information corresponding to each beam (e.g., RSRP, RSRQ, SINR) 4-2) Cell identification information (CGI, PCI, ARFCN) of PCell and PSCell and L1 / L3 quality information corresponding to each cell 4-3) Beam ID of adjacent beam and L1 / L3 quality information of the adjacent beam (e.g., RSRP, RSRQ, SINR) 4-4) Cell ID of neighboring cells and L1 / L3 quality information of the neighboring cells (e.g., RSRP, RSRQ, SINR) Beam ID / cell ID of candidate beam and candidate cell and L1 / L3 quality information of each candidate beam and candidate cell (e.g., RSRP, RSRQ, SINR) In this embodiment, the execution condition of the LTM or the execution condition of the SCG-conditional LTM may be an execution condition based on the physical layer (L1), or an execution condition based on the upper layer (L3).

[0069] An example of the operation procedure of this embodiment will be described with reference to Figures 2 to 4. These operation procedures show the mobility process including LTM in the UE 20 and the procedure for reporting information related thereto.

[0070] 2 is a sequence diagram showing an example of an operation procedure including transmission of an RLF report / handover failure report in the wireless communication system of this embodiment. In the example of FIG. 2, the UE 20 may be an IAB-MT (Integrated Access and Backhaul - Mobile Termination) or a WAB-MT (Wireless Access and Backhaul - Mobile Termination). The gNB 10 may be an IAB-donor or a BH (Backhaul)-gNB. This operation includes a scenario in which the UE reports mobility-related information when, for example, LTM in the MCG or SCG fails.

[0071] In step S101, the UE 20 detects an RLF, which occurs, for example, when the T304 timer expires after execution of conditional LTM in the MCG and an RRC connection is not established.

[0072] In step S102, the UE 20 sends an RRC Re-establishment Request message to the gNB 10. The UE sends the message to the most suitable cell as a means of initiating reconnection.

[0073] In step S103, the gNB 10 sends an RRC Re-establishment message to the UE 20. As a result, the gNB accepts the UE's re-establishment request and proceeds with the re-establishment procedure.

[0074] In step S104, the UE 20 transmits an RRC Re-establishment Complete message to the gNB 10. The RRC Re-establishment Complete message includes information indicating that an RLF report / handover failure report is available (RLF report / handover failure report available). The RLF report / handover failure report available may be included in an RRC Setup Complete message, an RRC Reconfiguration Complete message, or an RRC Resume Complete message. This availability flag allows the gNB 10 to determine whether the UE 20 holds mobility-related information and to perform an appropriate acquisition operation.

[0075] In step S105, the gNB 10 transmits a UE Information Request message to the UE 20. The UE Information Request message is a message for obtaining an RLF report or a handover failure report, which allows the gNB to obtain information about the cause of the LTM failure and the timing of the execution conditions.

[0076] In step S106, the UE 20 transmits a UE Information Response message to the gNB 10. The UE Information Response message includes an RLF report or a handover failure report. The RLF report or handover failure report includes at least one of the mobility-related information 1) to 4) above. For example, the inclusion of a timestamp difference (Time Between Fulfillment) between the LTM execution condition of the MCG and the execution condition of the SCG, or a time until failure (Time Between Last Fulfillment And Event) enables mobility optimization by the gNB 10.

[0077] 3 is a sequence diagram showing an example of an operation procedure including SHR transmission in the wireless communication system of the present embodiment. This operation is applied when, for example, when the conditional LTM of the MCG or SCG is successful, the UE notifies the gNB of success information through the SHR.

[0078] In step S201, the UE 20 sends an RRC Re-establishment Request message to the gNB 10. This step is the starting point of the re-establishment process after a successful LTM.

[0079] In step S202, the gNB 10 sends an RRC Re-establishment message to the UE 20.

[0080] In step S203, the UE 20 transmits an RRC Re-establishment Complete message to the gNB 10. The RRC Re-establishment Complete message includes information indicating that information about the successful handover is available (successHO-InfoAvailable). This information serves as a trigger to notify the gNB that it is ready to transmit an SHR.

[0081] In step S204, the gNB 10 sends a UE Information Request message to the UE 20. The UE Information Request message is a message for obtaining an SHR, which is a report indicating the success of the handover.

[0082] In step S205, the UE 20 transmits a UE Information Response message to the gNB 10. The UE Information Response message includes an SHR. The SHR includes at least one of the above-mentioned mobility-related information 1) to 4). This information may include the timing of successful execution of LTM, quality information of the candidate cell, the used beam ID, etc.

[0083] 4 is a sequence diagram showing an example of an operation procedure including transmission of SCG failure information in the wireless communication system of this embodiment. The example in FIG. 4 is directed to a reporting procedure by a UE when conditional LTM on the SCG side fails.

[0084] In step S301, the UE 20 detects a failure of the conditional LTM in the SCG and generates SCG failure information (SCGFailureInfo). The SCG failure information includes at least one of the above-mentioned mobility-related information 1) to 4). This allows the gNB to identify the cause of the SCG failure (e.g., PSCell change is not possible, selection conditions are not met, etc.).

[0085] In step S302, the UE 20 transmits the SCG failure information to the MN (Master Node) 10A. The SCG failure information includes information about the failure of the conditional LTM in the SCG. Upon receiving this information, the MN can review the SCG configuration and redesign the LTM parameters.

[0086] According to the above embodiment, information related to mobility performed by a terminal communicating using multiple cells can be reported to the network. This allows the network to determine when the execution conditions for conditional mobility are met in a master cell group (MCG) and a secondary cell group (SCG) based on the mobility-related information transmitted from the terminal. As a result, for example, when a conditional LTM involving a change of SCG fails, the cause can be identified, and the failure can be used as an effective indicator for optimizing the execution conditions for conditional LTM.

[0087] (Device configuration) Next, a description will be given of an example of the functional configuration of the base station (gNB 10) 10 and the terminal (UE 20) 20 that execute the processes and operations described above. The base station 10 and the terminal 20 include functions to execute the above-described embodiments. However, the base station 10 and the terminal 20 may each be equipped with only a part of the functions of the embodiments.

[0088] <Base station (gNB)> Fig. 5 is a diagram showing an example of the functional configuration of the base station 10 in this embodiment. As shown in Fig. 5, 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. 5 is merely an example. The functional divisions and names of the functional units may be any names as long as they can perform the operations in this embodiment. The transmitting unit 110 and the receiving unit 120 may be collectively referred to as a communication unit.

[0089] The transmitter 110 has a function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The transmitter 110 transmits setting information, instructions, notifications, etc. related to a low-power wake-up signal to the terminal 20. The transmitter 110 transmits notifications related to switching of monitoring operations to the terminal. The receiver 120 has 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 has a function of transmitting PSS, SSS, PBCH, DL / UL control signals, etc. to the terminal 20. The receiver 120 receives inter-network node messages from other network nodes.

[0090] The setting unit 130 stores preset setting information and various setting information to be transmitted to the terminal 20. The content of the setting information is, for example, information on the operations explained in the embodiments.

[0091] The control unit 140 controls the settings, instructions, and notifications related to the operations described in the embodiments. The function unit related to signal transmission in the control unit 140 may be included in the transmitting unit 110, and the function unit related to signal reception in the control unit 140 may be included in the receiving unit 120.

[0092] <Device (UE)> Fig. 6 is a diagram showing an example of the functional configuration of the terminal 20 in this embodiment. As shown in Fig. 6, 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. 6 is merely an example. The names of the functional divisions and functional units may be any as long as they can execute the operations in this embodiment. The transmitting unit 210 and the receiving unit 220 may be collectively referred to as a communication unit.

[0093] The transmitter 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The transmitter 210 transmits capability information in a 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 has a function of receiving PSS, SSS, PBCH, DL / UL / SL control signals, etc. transmitted from the base station 10. The receiver 220 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 a low-power wake-up signal from the base station 10. The configuration unit 230 stores various configuration information received from the base station 10 by the receiver 220. The configuration unit 230 also stores pre-configured configuration information. The configuration information includes, for example, information on the operations described in the embodiments.

[0094] As described in the embodiments, the control unit 240 controls settings, instructions, and notifications related to the operations described in the embodiments. A functional unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and a functional unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0095] (Hardware configuration) The block diagrams (FIGS. 5 and 6) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by hardware, software, or a combination of these. The method of realizing each functional block is not particularly limited. That is, each functional block may be realized by using one device that is physically or logically coupled, or may be realized by using two or more physically or logically separated devices that are connected directly or indirectly (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining the one device or the multiple devices with software.

[0096] For example, a base station, a terminal, a network node, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 7 is a diagram showing an example of the hardware configuration of a base station and a terminal according to an embodiment of the present disclosure. The above-described base station 10 and terminal 20 may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0097] In the present disclosure, the term "apparatus" may be interchangeable with any two terms selected from a set of terms such as circuit, device, unit, module, chip, means, etc. The hardware configurations of the base station 10 and the terminal 20 may be configured to include one or more of the devices shown in the drawings, or may be configured to exclude some of the devices.

[0098] Each function in the base station 10 and the terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001, memory 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls the reading, writing, or both reading and writing of data in the memory 1002 and storage 1003.

[0099] The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, a baseband signal processing unit, a call processing unit, etc. may be realized by the processor 1001. Although only one processor 1001 is shown in the figure, there may be multiple processors.

[0100] The processor 1001 reads programs (program codes), software modules, data, etc. from the storage 1003, the communication device 1004, or both the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes in accordance with the programs. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 401 of the terminal 20 may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and similar implementations may be made for other functional blocks. While the above-described various processes have been described as being executed by a single processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line, or may be provided to the computer via the communication device 1004, for example.

[0101] The present disclosure also provides a computer program product including a computer program, which may implement the steps of the methods described in the above embodiments when the computer program is executed by a computer (e.g., the processor 1001).

[0102] The memory 1002 is a computer-readable recording medium and may be configured, for example, as a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), or a combination of at least two of these. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), or the like. The memory 1002 can store executable programs (program codes), software modules, and the like for executing the wireless communication method according to one embodiment of the present disclosure.

[0103] Storage 1003 is a computer-readable recording medium, and may be, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, or a combination of at least two of these. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned storage medium may be, for example, memory 1002, storage 1003, or a database, server, or other appropriate medium including both memory 1002 and storage 1003.

[0104] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via a wired network, a wireless network, or both wired and wireless networks, and is also referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, or a combination of at least two of these. For example, a transmitting / receiving antenna, an amplifier unit, a transmitting / receiving unit, or a transmission path interface may be realized by the communication device 1004. The transmitting / receiving unit may be implemented as a transmitting unit and a receiving unit that are physically or logically separated.

[0105] The input device 1005 is an input device that receives input from the outside (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, or a combination of at least two of these). The output device 1006 is an output device that performs output to the outside (for example, a display, a speaker, an LED lamp, or a combination of at least two of these). The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0106] The processor 1001, memory 1002, and other devices are 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 the devices.

[0107] The base station 10 and the terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), a graphics processing unit (GPU), a neural processing unit (NPU), or a combination of at least two of these, and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0108] <Additional notes> (Additional note 1) a transceiver unit that communicates with a base station via a plurality of cells; a control unit that executes mobility when a predetermined execution condition is satisfied in each of the plurality of cells; The terminal, wherein the transceiver unit transmits information related to the mobility of at least one of the plurality of cells to a base station based on detection of failure or success of the performed mobility.

[0109] (Additional note 2) The terminal described in Supplementary Note 1, wherein the information related to the mobility includes a time interval between the time when the specified execution condition in a first cell among the plurality of cells is satisfied and the time when the specified execution condition in a second cell among the plurality of cells is satisfied.

[0110] (Additional note 3) The terminal according to claim 1, wherein the information related to the mobility includes a time interval from when the specified execution condition is satisfied to when a failure or success related to the mobility is detected.

[0111] (Additional note 4) The terminal described in Supplementary Item 1, wherein the mobility-related information includes beams in each of the plurality of cells and quality information corresponding to the beams.

[0112] (Additional note 5) The terminal of claim 1, wherein the mobility-related information is included in at least one of a radio link failure report, SCG failure information, or a report indicating a successful handover.

[0113] (Additional note 6) A communication method performed by a terminal, comprising: communicating with a base station via a plurality of cells; performing mobility in each of the plurality of cells when a predetermined execution condition is satisfied; and transmitting information related to the mobility of at least one of the plurality of cells to a base station based on detection of failure or success of the performed mobility.

[0114] According to the above configuration, information related to mobility performed by a terminal communicating using multiple cells can be reported to the network. This allows the network to determine when the execution conditions for conditional mobility are met in a master cell group (MCG) and a secondary cell group (SCG) based on the mobility-related information transmitted from the terminal. As a result, for example, when a conditional LTM involving a change of SCG fails, the cause can be identified, and the information can be used as an effective indicator for optimizing the execution conditions for conditional LTM.

[0115] (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.

[0116] The aspects / embodiments described in the present disclosure may be categorized as Long Term Evolution (LTE), LTE-Advanced (LTE-A), International Mobile Telecommunications-Advanced (IMT-Advanced), 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 5G-Advanced (5G-A), 6th generation mobile communication system (6G), xth generation mobile communication system (x is, for example, an integer or a decimal number)), Future Radio Access (FRA), New Radio (NR), New radio access (NX), Future generation radio access (FX), Open Radio Access Network (O-RAN), Wideband Code Division Multiple Access (W-CDMA) (registered trademark), Global System for Mobile communications (GSM) (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) Engineers) 802.11, IEEE802.11x (where x is any character string such as b, a, g, n, ac, ax, be, or bn, and when x=n it is called Wi-Fi4, when x=ac it is called Wi-Fi5, when x=ax it is called Wi-Fi6 or Wi-Fi6E, when x=be it is Wi-Fi7, and when x=bn it is called Wi-Fi8, etc. Wi-Fi is a registered trademark.), IEEE802.16 (WiMAX (registered trademark), IEEE802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), network virtualization technology (e.g., NFV (Network Function Virtualization), SFC (Service Function Chaining), SDN (Software Defined Networking)), or LPWA (Low Power Wide Area). Each aspect / embodiment described in the present disclosure may be applied to a system based on a combination of at least two of these technologies. Of course, "based on" may refer not only to a system that uses the technology, but also to a system that uses an extension or modification of the technology.

[0117] In the present disclosure, any two terms selected from a set of terms such as "base station (BS)", "radio base station", "fixed station (fixed station)", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point (AP)", "transmission point (TP)", "reception point (RP)", "transmission / reception point (TRP)", "radio unit (RU)", "remote unit (RU)", "control unit (CU)", "distributed unit (DU)", "remote radio head (RRH)", "node", "gateway", "terrestrial base station", "stratospheric base station", "unmanned aerial vehicle", "high altitude platform station (HAPS)", "airborne platform", "panel", "cell", "radio access network (RAN)", and "network" may be used interchangeably.

[0118] Each cell accommodated by a base station may be referred to by terms such as a macro cell, a small cell, a femto cell, a pico cell, a serving cell, or a super cell. In the present disclosure, any two terms selected from a set of terms such as "cell," "sector," "cell group," "carrier," "component carrier," "cluster," "bandwidth part (BWP)," and "carrier bandwidth" may be used interchangeably.

[0119] In the present disclosure, any two terms selected from the set of terms such as "Mobile Station (MS)", "user terminal", "User Equipment (UE 20)", "Device", "Module" and "Terminal" may be used interchangeably.

[0120] A terminal may be referred to as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, router (e.g., home router, mobile router, etc.), TCU (Telematics Control Unit), or some other suitable terminology.

[0121] The base station and the terminal may each be composed of one or more devices. The devices constituting at least a portion of the base station and the terminal may be called a transmitting device, a receiving device, a communication device, etc. Note that the devices constituting at least a portion of the base station and the terminal may be, for example, an object itself, such as a vehicle, a transport vehicle, an automobile, a motorcycle, a bicycle, a connected car, an excavator, a bulldozer, a wheel loader, a dump truck, a forklift, a train, a bus, a handcar, a rickshaw, a ship and other watercraft, an airplane, a rocket, an unmanned aerial vehicle, a stratospheric base station (e.g., a High Altitude Platform Station (HAPS)), an artificial satellite (e.g., a Low Earth Orbit (LEO) satellite, a Medium Earth Orbit (MEO) satellite, a Geostationary Earth Orbit (GEO) satellite), a drone (registered trademark), a multicopter, a quadcopter, a balloon, or an Internet of Things (IoT) device (e.g., a smart meter, a sensor), or may include, but are not limited to, an object or device mounted on the object. The object may be a moving object (hereinafter referred to as a "moving object"; this does not exclude the case where the moving object is in a stationary state where it is not moving), or may be a fixedly positioned object (hereinafter referred to as a "non-moving object").

[0122] A base station in the present disclosure may be read as a terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a terminal is replaced with communication between multiple terminals (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)) or communication of a non-terrestrial network (NTN). In this case, the terminal 20 may be configured to have at least some of the functions of the base station 10 described above. Terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "sidelink") or terms corresponding to NTN (for example, feeder link or service link). For example, an uplink channel or a downlink channel may be read as a sidelink channel.

[0123] The present disclosure is also applicable to cases where at least some of the devices constituting the base station and the terminal operate outside the ground (for example, in the atmosphere or outer space).

[0124] In this disclosure, the term "terminal" may be interpreted as a base station. In this case, the base station 10 may be configured to have the functions of the terminal 20 described above.

[0125] The notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI) and Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB) and System Information Block (SIB))), other signals, or a combination of at least two of these. Note that the physical layer signaling may be referred to as Layer 1 (L1) control information. The MAC signaling may be referred to as a MAC Control Element (CE) or a MAC Protocol Data Unit (PDU), for example. The RRC signaling may be referred to as an RRC message or an information element (IE) in the RRC message. The RRC message may be, for example, a message used for controlling an RRC connection (for example, setup, reconfiguration, establishment, reestablishment, release, or resume), mobility, a measurement report, or notification of a terminal's capabilities, or may be an information element within the message. Notification of information may be explicit or implicit. Note that explicit notification of certain information means notification of the certain information itself, and implicit notification of certain information may mean notification of information other than the certain information, or may mean that the certain information is considered to have been notified when a certain condition is satisfied.Notification of information may include not only notification between the same layers of different devices (e.g., between a lower layer or an upper layer of the base station 10 and the terminal 20) but also notification between different layers in the same or different devices (e.g., between a lower layer and an upper layer in the base station 10 or the terminal 20). Notification of information from one device to another device may be performed via one or more devices. With regard to any information (e.g., a variable, a constant, a parameter, a setting) described in the present disclosure, even if not specifically specified in the above embodiments, information indicating / specifying (or related to) the any information (value) may be notified from any first device (e.g., a terminal / base station) to any second device (e.g., a base station / terminal).

[0126] 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.

[0127] In the present disclosure, a specific operation described as being performed by a base station may be performed by its upper node or by some of its upper nodes (e.g., CU, RU, or DU, etc.) in some cases. It is clear that various operations performed for communication with a terminal in a RAN or core network may be performed by at least some of the base station and other network nodes other than the base station. The other network node may be one node or a combination of multiple nodes. The network node is, for example, a node provided in various core networks such as EPC (Evolved Packet Core) and 5GC (5G Core Network), and provides one or more network functions (NF: Network Functions), but is not limited to this.

[0128] In the present disclosure, the action of "a terminal receives information from a base station" accompanies the action of "the base station transmits the information to the terminal", "the base station generates the information", or both. Similarly, the action of "a terminal transmits information to a base station" accompanies the action of "the base station receives the information from the terminal". The actions of "the terminal is configured to..." or "configure UE 20 to..." may include the action of "the base station transmits configuration information regarding the configuration of the terminal" and the action of "the terminal configures a predetermined operation based on the configuration information".

[0129] Each aspect / embodiment described in the present disclosure may be used alone, in combination, or switched depending on the implementation.

[0130] The present disclosure has been described above, but it is for illustrative purposes only, and the present invention is not limited to the aspects / embodiments described in the present disclosure. The present disclosure can be implemented in modified and altered forms without departing from the spirit of the invention. The present disclosure and its modifications and alterations are included in the scope of the present invention and its equivalents.

[0131] 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.

[0132] The radio resource may be defined by a combination of resource units in one or more domains, such as the time domain, the frequency domain, the spatial domain, the code domain, and the power domain.

[0133] For example, resources in the time domain may be defined by one or more time units. The one or more time units may include, but are not limited to, a radio frame, a subframe, a slot, a symbol, a transmission time interval (TTI), or a combination of at least two of these. The time unit may be a fixed-length time unit independent of numerology, a variable-length time unit dependent on numerology, or both. Examples of fixed-length time units include, but are not limited to, a subframe consisting of one or more slots and a radio frame including multiple subframes. Examples of variable-length time units include, but are not limited to, a symbol and a slot including a fixed number of symbols. Note that a certain time unit may be divided into time units shorter than the certain time unit. Examples of shorter time units include, but are not limited to, a minislot consisting of fewer symbols than the number of symbols constituting a slot. The above-described time units may include, for example, time units used as units for scheduling, link adaptation, etc. Any time unit in the present disclosure may be read as another time unit.

[0134] Numerology is a parameter that defines the physical layer structure, and may be a parameter based on at least one of subcarrier spacing (SCS), symbol length, cyclic prefix length, and sampling time, for example.

[0135] Resources in the frequency domain may be defined, for example, by one or more frequency units. The one or more frequency units may include, for example, subcarriers, resource blocks (RBs), bandwidth parts (BWPs), carrier bandwidths, or a combination of at least two of these, but the terminology of the frequency units is not limited to these. The number of subcarriers included in a frequency unit may be a fixed number regardless of numerology, or may be a variable number that changes depending on numerology. For example, an RB is composed of a predetermined number of consecutive subcarriers in the frequency domain, and the number of subcarriers included in the RB may be the same regardless of numerology, for example, 12, but is not limited to this. A BWP may be composed, for example, of one or more consecutive RBs within a certain carrier bandwidth, but is not limited to this. One or more BWPs may be configured within one carrier for terminal 20, and at least one of the BWPs may be activated. Any frequency unit in the present disclosure may be interchangeable with another frequency unit.

[0136] Resources in both the time domain and the frequency domain may be defined by one or more time / frequency units, each of which is composed of a time unit and a frequency unit, such as, but not limited to, a resource element (RE) composed of one symbol and one subcarrier, a resource element group (REG) composed of a predetermined number of REs, or a control resource set (CORESET) composed of a predetermined number of symbols and a predetermined number of RBs.

[0137] The resources in the spatial domain may be defined, for example, by one or more spatial units, including, but not limited to, a beam, a layer of a multi-input multi-output (MIMO), an antenna port, or a combination of at least two of these.

[0138] The resources in the code domain may be defined by one or more code units, such as, but not limited to, a cyclic shift (CS), an orthogonal cover code (OCC), or a combination thereof.

[0139] 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.

[0140] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc. [Explanation of symbols]

[0141] 10 base station 110 Transmitter 120 Receiver 130 Setting section 140 Control Unit 20 terminals 210 Transmitter 220 Receiving unit 230 Setting Section 240 Control Unit 1001 processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication equipment 1005 Input Device 1006 Output Device

Claims

1. a transceiver unit that communicates with a base station via a plurality of cells; a control unit that executes mobility when a predetermined execution condition is satisfied in each of the plurality of cells; The terminal, wherein the transceiver unit transmits information related to the mobility of at least one of the plurality of cells to a base station based on detection of failure or success of the performed mobility.

2. 2. The terminal of claim 1, wherein the mobility-related information includes a time interval between a time when the predetermined execution condition is satisfied in a first cell among the plurality of cells and a time when the predetermined execution condition is satisfied in a second cell among the plurality of cells.

3. The terminal according to claim 1 , wherein the information related to the mobility includes a time interval from when the predetermined execution condition is satisfied until a failure or success related to the mobility is detected.

4. The terminal of claim 1 , wherein the mobility-related information includes beams in each of the plurality of cells and quality information corresponding to the beams.

5. The terminal according to claim 1 , wherein the mobility-related information is included in at least one of a radio link failure report, SCG (Secondary Cell Group) failure information, or a report indicating a successful handover.

6. A communication method performed by a terminal, comprising: communicating with a base station via a plurality of cells; performing mobility in each of the plurality of cells when a predetermined execution condition is satisfied; and transmitting information related to the mobility of at least one of the plurality of cells to a base station based on detection of failure or success of the performed mobility.

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