Terminal device, base station device, wireless communication system, control method, and program

Abstract

This terminal device receives preliminary setting for handover from a connected base station device to another base station device, including a list of beams formed by other base station devices serving as candidates of a beam to be used when a beam failure occurs; detects occurrence of a beam failure in the beam used for communication with the base station device; measures radio quality of a plurality of beams including the beam formed by the base station device and beams formed by the other base station devices shown in the list; and determines a beam to be used when the beam failure occurs on the basis of the measurement result.

Description

Terminal device, base station device, wireless communication system, control method, and program

[0001] The present invention relates to a terminal device, a base station device, a wireless communication system, a control method, and a program.

[0002] In a mobile communication system, as a terminal device moves, a handover is performed to switch the cell (base station device) to which the terminal device is connected. Conventionally, after receiving a handover instruction from a base station device, the terminal device performs a process of establishing a connection by establishing synchronization and setting up in the cell to which the connection is to be switched. This process of switching the connection takes a certain amount of time, and the terminal device cannot communicate user data while this process is being performed.

[0003] In contrast, in the technique described in Non-Patent Document 1, a handover source base station provides a terminal device with communication parameters in the radio resource control (RRC) layer for connection with another handover destination base station before the actual handover is performed. Then, the handover source base station transmits a Layer 1 or Layer 2 command to the terminal device at the timing when the handover is to be performed, instructing the terminal device to switch cells. Upon receiving the command, the terminal device executes a random access procedure with the handover destination base station, thereby completing the handover without subsequent configuration processing in the RRC layer. This cell switching technology is called LTM (L1 / L2 Triggered Mobility) and is intended to suppress degradation of communication efficiency related to handover.

[0004] 3GPP (registered trademark) Contribution, R2-2209255

[0005] Here, after the terminal device detects a beam failure (BFD: Beam Failure Detection), it transitions to a beam with better quality in the serving cell. On the other hand, if there is no beam with better quality, it determines that there is a radio link failure and performs a beam search in cells other than the serving cell. This creates the problem of it taking time to perform a beam search in cells other than the serving cell and perform a handover.

[0006] In view of such circumstances, the present disclosure aims to provide a technology that shortens the time it takes for a terminal device that detects a beam failure to perform a handover to a non-serving cell.

[0007] In order to achieve the above object, a terminal device according to one aspect of the present invention is characterized by comprising: a receiving means for receiving a pre-setting for handover from a connected base station device to another base station device, the pre-setting including a list of beams formed by the other base station device that are candidates for beams to be used when a beam failure occurs; a detecting means for detecting that a beam failure has occurred in a beam used for communication with the base station device; a measuring means for measuring the wireless quality of multiple beams including a beam formed by the base station device and a beam formed by the other base station device shown in the list; and a control means for determining a beam to be used when a beam failure occurs based on the measurement results of the measuring means.

[0008] According to the present invention, it is possible to provide a technique for shortening the time it takes for a terminal device that detects a beam failure to perform a handover to a non-serving cell.

[0009] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0010] The accompanying drawings are included in and constitute a part of the specification, illustrate embodiments of the present invention, and are used together with the description to explain the principles of the present invention. A diagram showing a wireless communication system according to this embodiment. A diagram showing the hardware configuration of a terminal device and a base station device. A functional configuration diagram of a terminal device. A functional configuration diagram of a base station device. A sequence diagram showing an example of beam search processing according to this embodiment. A flowchart showing an example of processing executed by a terminal device according to this embodiment. A flowchart showing an example of processing executed by a base station device according to this embodiment.

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] <System Configuration> Fig. 1 shows an example configuration of a wireless communication system according to this embodiment. The wireless communication system 1 is a wireless communication system that complies with the fifth generation (5G) cellular communication standard of the Third Generation Partnership Project (3GPP (registered trademark)). However, the wireless communication system is not limited to this, and may be, for example, a successor cellular communication system after 5G, or a wireless communication system other than a cellular system. The wireless communication system 1 includes a terminal device 10 and base station devices 20 and 30. Note that, although Fig. 1 shows one terminal device and two base station devices, the number of these devices is not limited.

[0013] The terminal device 10 is a wireless communication device capable of performing communication compliant with the 5G standard. The base station device 20 is a base station device connected to the terminal device 10. The base station device 20 can form multiple beams and provide communication services to the terminal device 10 using some of the multiple beams. The base station device 30 is a base station device that is a candidate for handover from the base station device 20. Note that, like the base station device 20, the base station device 30 can also form multiple beams, connect to the terminal device 10 using some of the beams, and provide communication services to the terminal device 10.

[0014] The terminal device 10 connects to the base station device 20 using one of a plurality of beams formed by the base station device 20, and transmits and receives uplink signals or downlink signals. Here, the base station device 20 transmits a reference signal (e.g., a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) or a channel state information-reference signal (CSI-RS)) in each of a plurality of beams. The terminal device 10 measures the radio quality of the reference signal transmitted from the base station device 20, determines the beam to use based on the radio quality, and connects to the base station device 20. Here, the radio quality includes, for example, reference signal received power (RSRP), reference signal received quality (RSRQ), received signal strength, signal-to-noise ratio (SNR), signal-to-noise and interference ratio (SINR), interference power, etc.

[0015] Thereafter, while performing communication via the beam, the radio quality is measured, and if the radio quality falls below a predetermined quality, it is detected that a beam failure has occurred.

[0016] Here, a conventional operation when a beam failure occurs will be described. When a terminal device 10 detects a beam failure, it measures other beams formed by the serving cell based on the measurement results of the beam that measured the radio quality, and determines the beam to connect to. Then, when it determines that a beam failure has occurred a predetermined number of times within a predetermined period, it determines that there is a radio link failure (Radio Link Failure), measures the beams of non-serving cells, and executes a reconnection process (RRC Re-establish).

[0017] In contrast, when a beam failure occurs, the terminal device 10 according to this embodiment determines the beam to be used for connection based on the measurement results of the beam of the serving cell and the beam of the non-serving cell. Note that the beam of the serving cell and the beam of the non-serving cell may be measured after the beam failure occurs, or the connection beam after the beam failure may be determined based on the measurement results measured before the beam failure. Then, when the terminal device 10 determines to use the beam of the non-serving cell, it executes a handover to the non-serving cell by LTM (L1 / L2 Triggered Mobility) described later. This allows for a quick handover to the non-serving cell when a beam failure occurs.

[0018] <Hardware Configuration> FIG. 2 illustrates the hardware configuration of the terminal device 10 and the base station devices 20 and 30 according to this embodiment.

[0019] In one example, the terminal device 10 and the base station devices 20 and 30 are configured to include a processor 101, a ROM 102, a RAM 103, a storage device 104, and a communication circuit 105. The processor 101 is a computer configured to include one or more processing circuits, such as a general-purpose CPU (central processing unit) or an ASIC (application-specific integrated circuit), and performs the overall processing of the device and each of the above-mentioned processes by reading and executing programs stored in the ROM 102 and the storage device 104. The ROM 102 is a read-only memory that stores information such as programs and various parameters related to the processing performed by the terminal device 10 and the base station devices 20 and 30. The RAM 103 functions as a workspace when the processor 101 executes the program and is a random access memory that stores temporary information. The storage device 104 is configured, for example, by a removable external storage device. The communication circuit 105 is configured, for example, by a circuit for wireless communication of 5G or its successor standards. Although FIG. 2 illustrates one communication circuit 105, the terminal device 10 and the base station devices 20 and 30 may have multiple communication circuits. For example, the terminal device 10 and the base station devices 20 and 30 may have wireless communication circuits for 5G and its successor standard, respectively, and a common antenna for these circuits. The terminal device 10 and the base station devices 20 and 30 may have separate antennas suitable for each standard. The base station devices 20 and 30 may also have wired communication circuits used when communicating with other base station devices or core network nodes. The terminal device 10 may also have communication circuits conforming to wireless communication standards other than cellular communication standards, such as a wireless local area network (LAN) or Bluetooth (registered trademark). The terminal device 10 and the base station devices 20 and 30 may have separate communication circuits 105 for each of multiple available frequency bands, or may have a common communication circuit 105 for at least some of these frequency bands.

[0020] <Functional Configuration> FIG. 3A shows an example of the functional configuration of the terminal device 10. The terminal device 10 includes a preset setting acquisition unit 201, a beam measurement unit 202, a beam obstruction detection unit 203, and an LTM control unit 204. Note that FIG. 3A only shows functions particularly related to this embodiment, and various other functions that the terminal device 10 may have are omitted from the illustration. For example, the terminal device 10 naturally has other functions that terminal devices compliant with 5G or subsequent standards generally have. Furthermore, the functional blocks in FIG. 3A are shown schematically, and each functional block may be realized by being integrated or further subdivided. Furthermore, each function in FIG. 3A may be realized, for example, by the processor 101 executing a program stored in the ROM 102 or the storage device 104, or by a processor within the communication circuit 105 executing predetermined software. Note that the details of the processes performed by each functional unit will not be described here, and only their general functions will be outlined.

[0021] The preset setting acquisition unit 201 acquires preset settings for executing handover by LTM from the base station device 20. Here, LTM is a handover procedure for handing over to the base station device 30 without performing connection control processing such as transmitting a HANDOVER REQUEST message to the base station device 20. After deciding to hand over the terminal device 10 to the base station device 30, the base station device 20 transmits preset settings to be used for communication with the base station device 30 that is a candidate cell for handover to the terminal device 10. In this case, the terminal device 10 uses the preset settings to perform connection settings with the base station device 30 before handover. This makes it possible to shorten the time until the terminal device 10 starts communicating user data with the base station device 30 after a handover event occurs.

[0022] The pre-configuration includes a beam failure detection configuration including a list of candidate beams to be used when a beam failure occurs, and a beam failure recovery configuration for performing an LTM-related handover when a beam failure occurs. The beam failure detection configuration includes a candidate (list) of beams to be used when a beam failure occurs. The terminal device 10 measures the list of beams and determines the beam to be used when a beam failure occurs. The beam failure recovery configuration includes an event ID and event information by the LTM, and the event information includes information that can identify the conditions for performing cell switching by the LTM. The conditions include, for example, a setting for comparing the measurement results of the beams in the list with the measurement results of the currently connected beam to determine whether to perform cell switching triggered by the terminal device 10. In one example, the beam failure detection configuration is notified by radioLinkMonitoringConfig, and the beam failure recovery configuration is notified by beamFailureRecoveryConfig.

[0023] The beam measurement unit 202 measures the wireless quality of one or more beams including the currently connected beam at a predetermined timing. For example, when the wireless quality of the currently connected beam falls below a predetermined threshold, the beam measurement unit 202 may measure one or more beams other than the currently connected beam, or may measure multiple beams at a predetermined cycle.

[0024] The beam failure detection unit 203 detects that a beam failure has occurred based on the wireless quality of the currently connected beam. In this embodiment, it is determined that a beam failure has occurred when the wireless quality of the currently connected beam falls below a predetermined threshold. In one example, when the beam measurement unit 202 measures a beam other than the currently connected beam at a predetermined period, it may determine that a beam failure has occurred when it detects a beam with better wireless quality than the currently connected beam or when it detects a beam with better wireless quality than the currently connected beam by a predetermined value or more.

[0025] FIG. 3B shows an example of the functional configuration of the base station devices 20 and 30. The base station devices 20 and 30 include, for example, a measurement report receiving unit 251, a candidate cell determining unit 252, and a preset providing unit 253. Note that FIG. 3B only shows functions particularly related to this embodiment, and various other functions that the base station devices 20 and 30 may have are omitted from the illustration. For example, the base station devices 20 and 30 naturally have other functions that base station devices compliant with 5G and subsequent standards generally have. The functional blocks in FIG. 3B are shown only schematically, and the respective functional blocks may be integrated or further subdivided. Furthermore, each function in FIG. 3B may be realized, for example, by the processor 101 executing a program stored in the ROM 102 or the storage device 104, or may be realized, for example, by a processor within the communication circuit 105 executing predetermined software. The details of the processes performed by each functional unit will not be described here, and only their general functions will be outlined.

[0026] The measurement report receiving unit 251 receives a measurement report of a beam measured by the terminal device 10 and determines whether to provide a pre-configuration to the terminal device 10. The candidate cell determining unit 252 determines a non-serving cell (candidate cell) that the terminal device 10 is permitted to execute handover by LTM based on the received measurement report. For example, from the received measurement report, the candidate cell determining unit 252 determines that a non-serving cell that forms a beam whose wireless quality is equal to or higher than a predetermined threshold is a candidate cell.

[0027] The pre-setting providing unit 253 obtains, from the candidate cell, identification information of the beam that the candidate cell can form and parameters used to connect to the candidate cell, and provides these to the terminal device 10 as pre-settings.

[0028] <Processing Example> A processing example executed in the wireless communication system 1 according to this embodiment will be described with reference to FIG.

[0029] In S101, the terminal device 10 connects to the base station device 20 and transitions to an RRC_Connected state. The terminal device 10 reports to the base station device 20 at least one of identification information of the beam used by the base station devices surrounding the terminal device 10 to transmit the reference signal and identification information of the surrounding base station devices, in association with the radio quality of the reference signal transmitted from the surrounding base station devices (S102). In this embodiment, in S102, the terminal device 10 transmits to the base station device 20 the measurement result of the reference signal transmitted from the base station device 30.

[0030] The base station device 20 determines a candidate cell to be a target for LTM based on the reported wireless quality (S103). The base station device 20 can select information about other base station devices to be included in the beam failure detection configuration and the beam failure recovery configuration based on the measurement results of reference signals transmitted from base station devices surrounding the terminal device 10 reported by the terminal device 10. In this embodiment, the base station device 20 determines the base station device 30 included in the measurement result report as one of the candidate cells. Next, the base station device 20 prepares a pre-configuration of the LTM candidate cell (S104). The pre-configuration includes a beam failure detection configuration to be used when a beam failure is detected and a beam failure recovery configuration to be used when recovering from the beam failure. The beam failure detection configuration includes a beam list to be measured for beam selection when a beam failure is detected. The beam list is associated with beam identification information and resource information on which the reference signal is transmitted. In one example, the beam list may further be associated with cell identification information. The beam failure recovery configuration may include information that can identify the resource of the random access (RA) preamble transmitted when switching cells, and configuration information used in the synchronization establishment process described below.

[0031] The base station device 20 includes the pre-settings prepared in S104 in an RRC_Reconfiguration message and transmits the message to the terminal device 10 (S105). The terminal device 10 that has received the RRC_Reconfiguration message stores the pre-settings and transmits an RRC_Reconfiguration_Complete message to the base station device 20 (S106).

[0032] Following S106, in one example, the terminal device 10 may perform pre-processing such as executing a process for establishing synchronization of uplink and downlink with the base station device 30 of the handover destination. Then, data communication with the base station device 20 is performed.

[0033] Thereafter, the terminal device 10 measures the wireless quality of the reference signal (SSB or CSI-RS) transmitted from the base station device 20 at a predetermined timing, and detects that a predetermined event has occurred (S107). The predetermined event includes, for example, the wireless quality of the beam used for the connection after establishing a connection with the base station device 20 falling below a predetermined threshold. In another example, the predetermined event includes, for example, the wireless quality of one of the beams formed by the base station device 30, which is a candidate cell, exceeding the wireless quality of the beam used by the terminal device 10.

[0034] Upon detecting a predetermined event, the terminal device 10 determines that a beam failure has occurred and executes a beam failure recovery process. The beam failure recovery process includes measuring at least one beam, including a beam formed by the base station device 20 and a beam formed by the base station device 30 (S108). The measurement of the beam measured in S108 is determined based on the pre-settings received in S105. However, in one example, the terminal device 10 may be configured to measure beams in pre-set resources. As shown in FIG. 4 , the beam measurement may include measurement of beams formed by the base station device 20, including the beam used by the terminal device 10 for connection. In this embodiment, it is determined that the radio quality of the beam formed by the base station device 30 is the best based on the measurement results of the terminal device 10.

[0035] Next, the terminal device 10 determines a target cell for cell switching (S109). As described above, the terminal device 10 determines that the beam formed by the base station device 30 is the best beam, and therefore performs cell switching to the base station device 30. However, if the terminal device 10 determines that the beam formed by the base station device 20 is the best beam, beam switching is performed instead of cell switching. Here, the cell switching process is a form of handover defined in the LTM, and is a process of starting a random access procedure to the base station device 30 without transmitting a handover request or an RRC message to the base station device 20. In other words, in the cell switching process, the random access procedure is started while maintaining connection with the base station device 20 (S110, S111). The terminal device 10 that has successfully connected to the base station device 30 transmits an RRC Reconfiguration Complete message to the base station device 30 and completes cell switching (S112).

[0036] As described above, when the terminal device 10 according to this embodiment performs beam measurement upon detecting the occurrence of a predetermined event, it can also measure beams formed by a base station device 30 other than the currently connected base station device 20, and execute cell switching. This enables high-speed switching to a non-serving cell when a beam failure occurs. This makes it possible to minimize communication interruptions and reductions in communication speed experienced by the user.

[0037] In addition, when performing beam failure recovery processing, the beam failure recovery processing can be performed in neighboring cells, including non-serving cells, thereby enhancing the network coverage area.

[0038] Furthermore, even if the serving cell becomes temporarily inoperable due to a failure, the terminal device connected to the serving cell can be quickly switched to a non-serving cell, thereby improving the fault tolerance of the entire communication system.

[0039] In addition, while handover was previously required after a certain number of beam failure recovery attempts in the serving cell, by implementing handover at the time of beam failure, the length of the period during which wireless quality is low can be minimized.

[0040] In the example of Fig. 4, the beam to be used for connection is determined based on the beam measurement result after the event detection. However, the beam to be used for connection may also be determined based on the beam measurement result before the event detection. In this case, the order of S107 and S108 in Fig. 4 may be reversed. This allows handover to be performed quickly after the event detection, and the length of the beam failure period can be shortened.

[0041] <Example of processing executed by terminal device> Fig. 5 shows an example of processing executed by the terminal device according to this embodiment. The processing shown in Fig. 5 may be realized by the processor 101 of the terminal device 10 executing a program stored in the ROM 102 or the storage device 104, or may be realized by a processor present inside the communication circuit 105 executing predetermined software, for example.

[0042] In S201, the terminal device 10 connects to the base station device 20 and transmits a measurement report to the base station device 20 (S202).

[0043] Next, the RRC Reconfiguration message is received (S203), a pre-configuration used for recovering from beam interference is received, and an RRC Reconfiguration Complete message is transmitted (S204).

[0044] Next, it is determined whether a beam failure has occurred (S205), and if a beam failure has occurred, beam measurement is performed in the serving cell and non-serving cells (S206). In S206, in addition to the beam formed by the serving cell and the beam that can be formed by a candidate cell specified in advance, a predetermined beam not specified in advance may be measured. For example, it is possible to measure a beam transmitted using resources specified in advance in the communication system 1, a beam transmitted using resources preset in the terminal device 10, or a beam to be measured that the serving cell has notified multiple terminal devices of using a beacon or the like.

[0045] Here, if it is determined that the best beam is the beam formed by a non-serving cell (Yes in S207), cell switching is performed (S208), and if the beam formed by the serving cell is the best beam (No in S207), beam switching is performed (S209). Note that after beam switching, data communication may be performed until beam failure occurs again.

[0046] In addition, if the terminal device 10 determines in S206 that the best beam is a beam other than the beam formed by the serving cell and the beam that can be formed by the candidate cell specified in the pre-settings, it executes a reconnection process (RRC Re-establish) instead of a handover by LTM.

[0047] <Example of Processing Executed by Base Station Device> An example of processing executed by the base station device according to this embodiment is shown in Fig. 6. The processing shown in Fig. 6 may be implemented by the processor 101 of the base station device 20 executing a program stored in the ROM 102 or the storage device 104, or may be implemented by a processor present inside the communication circuit 105 executing predetermined software, for example.

[0048] When a connection is made with the terminal device 10 in S301, a measurement report is received from the terminal device 10 (S302). Subsequently, a candidate cell for LTM cell switching is determined based on the received measurement report (S303). Subsequently, a beam failure detection setting and a beam failure recovery setting for executing LTM handover are acquired from the candidate cell (S304, S305). The beam failure detection setting is a setting used when detecting beam failure and measuring a beam formed by a base station device other than the currently connected base station device 20. In this embodiment, the beam failure detection setting includes identification information of a beam formed by the base station device 30 that is a non-serving cell. The beam failure recovery setting includes parameters used when executing LTM-related handover to the base station device 30 that is a non-serving cell. Then, the beam failure detection setting and the beam failure recovery setting are transmitted to the terminal device 10 as pre-settings.

[0049] As described above, the terminal device according to this embodiment receives a preset list of beams to be used when a beam failure occurs, the preset list including beams formed by non-serving cells. This allows the terminal device to use beams formed by non-serving cells when a beam failure occurs. Therefore, when the radio quality of the beam of the serving cell deteriorates, a quick handover can be performed.

[0050] Furthermore, the base station device according to this embodiment receives a beam measurement report from the terminal device, determines candidate cells for handover by LTM from the terminal device, and transmits the beams formed by the candidate cells as a list of beams to be used when a beam failure occurs. This makes it possible to use beams formed by non-serving cells when a beam failure occurs.

[0051] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

[0052] This application claims priority based on Japanese Patent Application No. 2024-056619, filed March 29, 2024, the entire contents of which are incorporated herein by reference.

[0053] 1: wireless communication system, 10: terminal device, 20, 30: base station device

Claims

1. A terminal device comprising: a receiving means for receiving a pre-setting for handover from a connected base station device to another base station device, the pre-setting including a list of beams formed by the other base station device that are candidates for beams to be used when a beam failure occurs; a detecting means for detecting that a beam failure has occurred in a beam used for communication with the base station device; a measuring means for measuring the wireless quality of multiple beams including a beam formed by the base station device and a beam formed by the other base station device shown in the list; and a control means for determining a beam to be used when a beam failure occurs based on the measurement results of the measuring means.

2. The terminal device according to claim 1, wherein the receiving means receives the pre-configuration via an RRC Reconfiguration message.

3. The terminal device according to claim 1 or 2, wherein the pre-settings include setting information used for handover to the other base station device.

4. A terminal device as described in any one of claims 1 to 3, further comprising: a second detection means for detecting the occurrence of a radio link failure in response to the detection means detecting that a beam failure has occurred a predetermined number of times within a predetermined period; and an execution means for executing a reconnection process when the second detection means detects that the radio link failure has occurred.

5. A base station device comprising a transmitting means for transmitting to a terminal device connected to the base station device a pre-setting for handover to another base station device, the pre-setting including a list of beams formed by the other base station device that are candidates for a beam to be used when a beam failure occurs.

6. The base station device according to claim 5, further comprising an acquisition means for acquiring, from said other base station device, identification information of a beam that said other base station device can form.

7. A wireless communication system comprising a first base station device, a second base station device, and a terminal device, wherein the terminal device comprises: a receiving means for receiving a pre-setting for handover from the currently connected first base station device to the second base station device, the pre-setting including a list of beams formed by the second base station device that are candidates for beams to be used when a beam failure occurs; a detecting means for detecting that a beam failure has occurred in a beam used for communication with the first base station device; a measuring means for measuring the wireless quality of multiple beams including a beam formed by the first base station device and a beam formed by the second base station device shown in the list; and a control means for determining a beam to be used when a beam failure occurs based on the measurement results of the measuring means; and wherein the first base station device comprises a transmitting means for transmitting to the terminal device a pre-setting for handover to the second base station device, the pre-setting including a list of beams formed by the second base station device that are candidates for beams to be used when a beam failure occurs.

8. A control method for a terminal device, comprising: receiving a pre-configuration for handover from a connected base station device to another base station device, the pre-configuration including a list of beams formed by the other base station device that are candidates for beams to be used when a beam failure occurs; detecting that a beam failure has occurred in a beam used for communication with the base station device; measuring the wireless quality of multiple beams including the beam formed by the base station device and the beam formed by the other base station device shown in the list; and determining, based on the measurement results, a beam to be used when a beam failure occurs.

9. A control method for a base station device, comprising transmitting to a terminal device connected to the base station device a pre-setting for handover to another base station device, the pre-setting including a list of beams formed by the other base station device that are candidates for the beam to be used when a beam failure occurs.

10. A control method executed by a wireless communication system including a first base station device, a second base station device, and a terminal device, comprising: receiving, in the terminal device, a pre-setting for handover from the currently connected first base station device to the second base station device, the pre-setting including a list of beams formed by the second base station device that are candidates for beams to be used when a beam failure occurs; detecting that a beam failure has occurred in a beam used for communication with the first base station device; measuring the wireless quality of multiple beams including the beam formed by the first base station device and the beam formed by the second base station device shown in the list; and determining, based on the measurement results, a beam to be used when a beam failure occurs; and in the first base station device, transmitting, to the terminal device, a pre-setting for handover to the second base station device, the pre-setting including a list of beams formed by the second base station device that are candidates for beams to be used when a beam failure occurs.

11. A program for causing a computer to function as the terminal device according to any one of claims 1 to 4.

12. A program for causing a computer to function as the base station device according to claim 5 or 6.

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