WO2021095335A1

WO2021095335A1 - Terminal device for selecting cell on basis of communication service, base station device, control method, and program

Info

Publication number: WO2021095335A1
Application number: PCT/JP2020/034029
Authority: WO
Inventors: 洋樹武田; 忍難波; 渡辺　伸吾; 優塚本; 透北藪
Original assignee: Kddi株式会社
Priority date: 2019-11-14
Filing date: 2020-09-09
Publication date: 2021-05-20
Also published as: JP2021082859A

Abstract

This terminal device acquires information indicating the required radio quality for at least one of one or more communication services that can be respectively provided by one or more base station devices, measures the radio quality between the one or more base station devices, and selects a base station device to be connected when the terminal device is shifted to a connection state from the one or more base station devices, on the basis of a communication service that can be executed by the terminal device, information indicating the acquired radio quality of the communication service, and the measured value of the measured radio quality.

Description

Terminal equipment, base station equipment, control methods, and programs for cell selection based on communication services

The present invention relates to a terminal device, a base station device, a control method, and a program, and particularly to a cell selection technique based on a communication service.

In a cellular communication network, a plurality of cells are formed by one or more base station devices, and communication is performed between a terminal device and a base station device located in at least one of the plurality of cells. In such a cellular communication network, when the terminal device is in the standby state in which communication is not performed, cell selection is executed to select which cell among a plurality of cells is to perform standby. The terminal device establishes a connection with the base station device via the selected cell and communicates with the terminal device, for example, by a paging signal from the base station device or when data to be transmitted is generated.

In recent years, in the 3rd Generation Partnership Project (3GPP), network slices that virtually divide the network according to the purpose of communication have been discussed. By connecting to a base station device that supports a network slice for a service that its own device can execute, the terminal device can perform communication using the network slice for that service. At this time, since the supported network slices may differ for each base station device (see Non-Patent Document 1), the terminal device is connected to the base station device that supports the network slice corresponding to the service to be executed. That is essential.

The terminal device cannot know which network slice each base station device supports in the standby state. Therefore, the terminal device may connect to a base station device that does not support the desired network slice, and as a result, communication for the service to be executed may not be possible.

The present invention provides a technique that enables a terminal device to select an appropriate base station device as a connection target in consideration of communication services.

The terminal device according to one aspect of the present invention includes acquisition means for acquiring information indicating required radio quality for at least one of one or more communication services that can be provided by one or more base station devices, and the above-mentioned acquisition means. The measuring means for measuring the radio quality between each of the one or more base station devices, the communication service that the terminal device can execute, the information indicating the radio quality for the communication service, and the measured. It has a selection means for selecting a base station device to which the terminal device is connected from the one or more base station devices based on a measured value of radio quality.

The base station apparatus according to one aspect of the present invention is information indicating the required radio quality for at least one of one or more communication services that can be provided by each of the one or more base station apparatus including the base station apparatus. Has a notification means for notifying the terminal device.

According to the present invention, the terminal device can select an appropriate base station device as a connection target in consideration of the communication service.

Other features and advantages of the present invention will be clarified by the following description with reference to the accompanying drawings. In the attached drawings, the same or similar configurations are designated by the same reference numbers.

The accompanying drawings are included in the specification and are used to form a part thereof, show embodiments of the present invention, and explain the principles of the present invention together with the description thereof.
FIG. 1 is a diagram showing a configuration example of a wireless communication system. FIG. 2 is a diagram showing a hardware configuration example of a base station device and a terminal device. FIG. 3 is a diagram showing a configuration example of the base station device. FIG. 4 is a diagram showing a configuration example of the terminal device. FIG. 5 is a diagram showing an example of a processing flow executed by the system.

Hereinafter, embodiments will be described in detail with reference to the attached drawings. The following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. Further, the same or similar configuration will be given the same reference number, and duplicate description will be omitted.

(System configuration)
FIG. 1 shows a configuration example of the wireless communication system according to the present embodiment. In the example of FIG. 1, three base station devices and one terminal device are shown, but of course, there may be a larger number of base station devices and terminal devices than these. The base station device 101 to the base station device 103 are, for example, radio base station devices in a fifth generation (5G) cellular communication system. Each of the base station device 101 to the base station device 103 is configured to be able to communicate with a terminal device existing in the range of the cells in the cells 111 to 113, which is the range in which the own device can communicate.

The terminal device 121 can perform wireless communication by connecting to a base station device that provides a cell including a position where the own device exists and entering a connected state (for example, RRC_Connected state). When the user data to be transmitted / received does not exist, the terminal device 121 can suppress power consumption by transitioning to a standby state (for example, RRC_Idle state or RRC_Inactive state) and performing intermittent reception.

Conventionally, a terminal device in a standby state measures the radio quality of a radio signal from a surrounding base station device on a regular basis or when a specific condition is satisfied, and the measured value and Qrxlevmin (Minimum) regarding the radio quality are measured. Select the base station device (cell) to be connected when the transition to the connection state (RRC_Connected state) should be performed based on a predetermined reference value called (required RX level in the cell). Here, the value of Qrxlevmin is a value that can be adjusted for each telecommunications carrier, and can be notified from the core network to the connected terminal device via each base station device, for example. The terminal device measures the radio quality using, for example, reference signals transmitted from each of one or more base station devices, and the difference value between the measured value and Qrxlevmin exceeds a predetermined value (for example, 0). Is extracted. Then, the terminal device identifies the base station device that is the source of the radio signal having the highest radio quality among the extracted radio signals, and selects the specified base station device as the base station device to be connected.

In the above example, the optimum base station device (cell) is selected when shifting to the connected state (RRC_Connected state), but before the transition to the connected state, the predetermined reference of the above Qrxlevmin is selected in advance. Based on the value, the base station device (cell) that the terminal device should stand by may be selected in advance. In the following, when the connection state should be changed by combining the selection of the connection destination base station device at the time of the connection state transition and the selection of the connection destination base station device performed in advance before the transition to the connection state. It is expressed as the selection of the base station device to be connected. In addition, instead of Qrxlevmin, a base station device (cell) used for standby or connection is selected based on a predetermined reference value called Qqualmin (Minimum required quality level in the cell) or based on Qrxlevmin and Qqualmin. You may. In the following description, the case where the base station device (cell) is selected based on Qrxlevmin will be described. However, in the following description as well, the base station device is considered in place of or in addition to Qrxlevmin. (Cell) may be selected.

The terminal device can specify in advance the communication service that the own device can (or should) execute. For example, in a terminal device attached to an industrial robot used in a factory or the like, only communication for controlling the terminal device is performed, and contents such as voice calls and moving images are not downloaded. Further, in the terminal device that executes streaming, the moving image can be downloaded in real time. For these communication services, as described above, the network may be logically divided to form a network slice corresponding to each communication service. At this time, each base station device may correspond to a different network slice, and in this case, the terminal device is connected to a base station device that supports the network slice corresponding to the desired communication service. Communication of communication service can be performed.

On the other hand, the terminal device can acquire a list of provided network slices from the core network via the base station device for each tracking area. However, the terminal device has conventionally been unable to recognize which network slice each base station device supports before connecting to the base station device. Also, the required wireless quality may vary from communication service to communication service. For example, for machine control and voice call services, it is sufficient to communicate a small amount of data, so the required wireless quality is relatively low, while for communication services such as streaming large volumes of moving images, a large amount of data is required. Since data communication is required, the required wireless quality is also relatively high.

Thus, in the present embodiment, the terminal device is of the required radio quality for at least one of the one or more communication services that each of the one or more base station devices can provide before establishing the connection. Try to get information. Then, the terminal device measures the radio quality between each of the one or more base station devices, and the communication service that the own device can execute, the radio quality information acquired about the service, and the radio quality. Based on the measured values, select the base station device to be connected when the connection state should be entered.

For example, one or more base station devices may have a required radio quality (eg, Qrxlevmin) value for at least one of the one or more communication services that each of the one or more base station devices, including its own device, can provide. Is notified to the terminal device. The base station apparatus can, for example, notify the terminal apparatus of the highest Qrxlevmin value among the values of Qrxlevmin corresponding to one or more communication services that each base station apparatus can provide. That is, the Qrxlevmin for the communication service with the most demanding radio quality can be notified to the terminal device. According to this, the terminal device is in a state where the radio quality exceeding the value of Qrxlevmin corresponding to the selected base station device can be obtained, so that the radio quality capable of executing all the communication services that can be executed by the base station device is high. It can be guaranteed that it is in the obtained state.

In addition, the base station device may notify the terminal device of Qrxlevmin only for important predetermined communication services among the communication services that the base station device can provide. For example, communication services and Qrxlevmin only for predetermined communication services set by the telecommunications carrier, such as communication services for controlling important equipment, communication services for controlling medical equipment, and communication services for controlling construction machinery. The relationship may be notified to the terminal device. According to this, the terminal device is in a state where the radio quality exceeding the value of Qrxlevmin corresponding to the selected base station device can be obtained, so that the important communication service among the communication services that can be executed in the base station device is selected. It can be ensured that viable radio quality is obtained. Further, the base station apparatus may notify, for example, the value of Qrxlevmin corresponding to all of one or more communication services that each base station apparatus can provide. In these cases, the base station apparatus has, for example, a first Qrxlevmin value (for example, -110 dBm) for the first communication service and a second Qrxlevmin value (for example, -115 dBm) for the second communication service. Etc.), ..., etc. can be notified. Note that these notifications may be given in addition to the conventional Qrxlevmin notification when the network slice is not considered, or may be given instead of the conventional notification. For example, the first Qrxlevmin corresponds to the conventional Qrxlevmin, and the second Qrxlevmin, the third Qrxlevmin ... May correspond to a predetermined communication service, respectively.

Note that the value of Qrxlevmin is only an example, and arbitrary information indicating the wireless quality required for each communication service can be used. For example, an offset value corresponding to the difference between the value of Qrxlevmin and the reference value may be used as information indicating radio quality. For example, the value of the first Qrxlevmin corresponding to the first communication service is used as a reference value, and the value of the second Qrxlevmin corresponding to the second communication service is the value of the second Qrxlevmin and the value of the first Qrxlevmin. It can be notified as a difference value from the value. Further, the average value of Qrxlevmin values for a plurality of communication services may be used as a reference value, and the value of Qrxlevmin for a plurality of communication services may be notified as a difference value from the reference value. According to this, when the reference value is −110 dBm, the value of Qrxlevmin of -115 dBm is indicated as “-5” or the like. Further, for example, a threshold value of the interference level for selecting a cell in a situation below the threshold value may be used as the required radio quality. Further, for example, RSRP (reference signal reception power) or RSRQ (reference signal reception quality) defined in the service level agreement may be used as the required radio quality. Further, the required radio quality may be determined by other criteria such as the magnitude of power fluctuation due to fading and transmission delay.

Note that the base station device can notify the terminal device of information as radio quality information in which the required radio quality value and the identification information of the communication service corresponding to the value are associated with each other. The identification information is, for example, S-NSSAI (Single-Network Slice Selection Assistance Information). For example, information such as Qrxlevmin_1 = −110 dBm for S-NSSAI = 1 and Qrxlevmin_2 = -115 dBm for S-NSSAI = 2 can be notified. This shows that the value of Qrxlevmin corresponding to the communication service of S-NSSAI 1 is -110 dBm, and the value of Qrxlevmin corresponding to the communication service of S-NSSAI 2 is -115 dBm. Further, for example, one value of Qrxlevmin may be associated with the identification information of a plurality of communication services. In this case, for example, notifications such as Qrxlevmin_1 = (-110 dBm: S-NSSAI = 1, 3), Qrxlevmin_2 = (-115 dBm: S-NSSAI = 2, 5) can be given. This indicates that the value of Qrxlevmin corresponding to the communication service of S-NSSAI 1 or 3 is -110 dBm, and the value of Qrxlevmin corresponding to the communication service of S-NSSAI 2 or 5 is -115 dBm. .. By clarifying the relationship between the communication service and the required wireless quality in this way, the terminal device can select the cell in standby according to the communication service to be executed in the own device.

The base station device can notify the required radio quality value for each communication service by a broadcast signal such as a system information block (SIB). According to this, the terminal device in the standby state can surely acquire the information of the required radio quality. The base station apparatus can also notify the required radio quality information not only for the own apparatus but also for other base station apparatus such as an adjacent base station apparatus. According to this, when the terminal device moves to the cell end or the like, the radio communication with the other base station devices around the terminal device without acquiring the required radio quality information again from the other base station devices around the terminal device. The quality can be measured and the base station equipment to be connected when the transition to the connected state should be made can be selected. At this time, the base station apparatus can notify the terminal apparatus of information common to the plurality of base station apparatus by simple information. For example, the base station device has a small number of bits such as 1 bit indicating that the information about the base station device is common to the own device for other base station devices having the same information on the required radio quality as the own device. It can be expressed and other matters can be omitted. Further, the base station device notifies the terminal device of only the difference between the required radio quality information of the own device and the required radio quality information of the other base station device as information about the other base station device. May be good. When the base station device notifies the required radio quality information about its own device, for example, when the terminal device moves from outside the service area to the cell formed by the base station device, the terminal device is based on the desired value of the radio quality. , Can perform cell selection. The terminal device can also perform cell selection when the power is turned on, based on this required radio quality value. In addition, when the base station device notifies the required radio quality information about another base station device such as an adjacent base station device, the terminal device moves from the currently standby cell to another cell. You can use the value. The base station device notifies the terminal device of the required radio quality information of its own device by SIB1, and the information of the required radio quality of another base station device is another information such as SIB2 / 3/4. Can be notified by block.

Further, when the base station device supports a plurality of frequency bands, the cells developed in each of the plurality of frequency bands can be treated as different cells. Therefore, the base station apparatus can separately notify the required radio quality information corresponding to the executable communication service for each of the plurality of frequency bands. For example, for a common communication service, a different Qrxlevmin value for each frequency band can be notified to the terminal device. In this case, for example, in the broadcast signal transmitted in each frequency band, this notification can be performed by transmitting the information of the required radio quality corresponding to the frequency band. Further, when one base station device is shared by a plurality of operators, different required radio quality information may be notified for each network identifier. For example, for a common communication service, the PLMN (Public Land Mobile Network) / NID (Network ID) of the first operator and the value of the first required radio quality are associated with the PLMN / NID of the second operator. A second required radio quality value can be associated and notified to the terminal device. This makes it possible to assign different required communication qualities to common communication services for each operator. The communication service that can be provided may differ for each operator, and in that case, the information on the required radio quality corresponding to the communication service may be notified to the terminal device for each operator.

Further, the base station device may notify the terminal device connected to the own device of the required radio quality information. For example, when the base station device uses a common required radio quality value corresponding to a common communication service in the base station device within the range of RNA (RAN Notification Area) set for the connected terminal device, the value of the required radio quality is used. Information on the required radio quality can be notified to the terminal device. Further, when a common required radio quality value is used for a common communication service for a base station device in a tracking area, the base station device can notify the terminal device of the information to the connected terminal device. When the terminal device moves beyond the range of RNA in the RRC_Inactive state, or when it moves beyond the range of the tracking area in the RRC_Inactive state or the RRC_Idle state, the terminal device once transitions to the RRC_Connected state. In the connected state, the base station device can individually transmit a large amount of data to the terminal device. Therefore, when the terminal device moves from a predetermined area to another area and transitions to the RRC_Connected state, information on the required radio quality corresponding to the communication service, which is common to the other area, is notified. By doing so, it is possible to efficiently notify the terminal device of the required wireless quality information for each communication service. Since the base station device can transmit a large amount of data to the connected terminal device, even if the required radio quality value is different in each base station device in the area, all of them are used. You can also notify.

By narrowing down the information to information common to each base station device, for example, an RRC Resume message transmitted from the base station device to the terminal device when the terminal device shifts from the RRC_Inactive state to the RRC_Connected state, or the terminal device RRC_Idle. It is also possible to efficiently notify the terminal device of this information by individual notification such as individual signaling such as the RRCSetup message transmitted from the base station device to the terminal device when shifting from the state to the RRC_Connected state. In addition, the RRC Supend message sent from the base station device to the terminal device when shifting from the RRC_Connected state to the RRC_Inactive state, and the RRC release sent from the base station device to the terminal device when the terminal device shifts from the RRC_Connected state to the RRC_Idle state. The same effect can be obtained even if the information is individually notified to the terminal device by a message or the like.

When the requested radio quality information is notified by individual notification to the connected terminal device, the information customized for the terminal device may be notified. For example, only information about communication services that the terminal device can execute may be notified. As a result, it is possible to prevent the terminal device from being notified of information that is not used, and to prevent waste of wireless resources due to the notification.

In addition, the standard information common to each base station device is individually notified while the terminal device is connected, and the value of the difference between the required radio quality value in each base station device and the reference information is sent to each base station device. May be notified by a broadcast signal or the like. For example, each base station device may notify only the identification information indicating the communication service that can be provided by the own device by the broadcast signal. The terminal device in the standby state determines, for example, whether or not the base station device supports the communication service that the own device can execute based on the information indicating the communication service that can be provided by each base station device. Then, the terminal device may select a cell by comparing the requested radio quality information acquired during the connection state with the measured value of the radio quality for the supported communication service. Further, each base station device has, for example, a reference indicated by the required radio quality value as information on the required radio quality for the communication service that can be provided and the reference information notified as a value common to a plurality of base station devices. The information represented by the difference from the value may be notified to the terminal device by a broadcast signal. In this case, the terminal device in the standby state performs an operation such as adding (or subtracting) the difference value acquired by the broadcast signal from a certain base station device to the reference value acquired during the connected state. The value of the required radio quality of the base station device can be calculated. This makes it possible to notify the terminal device of the required radio quality information while efficiently using the broadcast signal in which the amount of data that can be transmitted is limited. In addition, each base station device notifies the connected terminal device of information indicating the communication service commonly supported by each base station device in a predetermined area, and the communication service thereof is transmitted by a broadcast signal. Requests for radio quality information may be notified.

In the above-described embodiment, it is explained that each base station device notifies the terminal device of the required radio quality information corresponding to the communication service, but this is acquired by the base station device from another device. It also includes a mode of notifying the terminal device of the information. That is, the base station device does not need to generate and manage the required radio quality information in its own device. The other device here may be a predetermined device in the core network, or may be, for example, a server device independently set by the telecommunications carrier. For example, when the terminal device is connected to any of the base station devices, it is possible to voluntarily inquire about information such as required radio quality, but the inquiries at that time are the base station device and the core device. , Server equipment, etc., can be set as appropriate depending on the network design.

As described above, the terminal device can specify the communication service supported by each base station device and the required radio quality corresponding to the communication service. Then, the terminal device is a base of a wireless signal source that can obtain a wireless quality measurement value that satisfies the required wireless quality for all communication services that the own device can execute (contracted by the user of the terminal device). The station device can be selected as the base station device to be connected when the transition to the connected state should be made. Further, the terminal device is, for example, a base station device of a radio signal source that can obtain a radio quality measurement value that satisfies the required radio quality for a communication service that is set to be indispensable among the communication services that the own device can execute. May be selected as the base station device to be connected when the transition to the connected state should be made. Further, the terminal device shifts the base station device of the source of the wireless signal that can obtain the measured value of the wireless quality satisfying the required wireless quality to the connected state, for example, for any of the communication services that the own device can execute. It may be selected as a base station device to be connected when it should be.

Note that the base station device may notify the terminal device of the congestion status (of the network slice) and the regulation information for each communication service in addition to or instead of the above-mentioned required radio quality information. Based on this information, the terminal device can select a base station device that is not in a congested state or a regulated state as a base station device to be connected when it should shift to the connected state.

Based on the above information, the terminal device has, for example, (1) when the power is turned on, and (2) during standby, the radio quality of the radio signal from the selected base station device is first. (3) During standby, the radio quality of the radio signal from the base station device different from the selected base station device has improved to the extent that it exceeds the second predetermined value. In the case of (4) when there is a change in the communication service that can be executed by the terminal device during standby, and (5) when there is a change in the communication service that can be provided by the selected base station device during standby. , Etc., cell selection can be performed. Further, when the communication service is started to be executed during standby, if the selected base station device cannot execute the communication service, the terminal device executes cell selection as described above and connects. You may choose the base station device to try. Further, when the terminal device moves to an area outside the service area during communication or the like, the terminal device executes the above-mentioned process to select the base station device. Then, when the terminal device can select the base station device capable of communicating within the specified time, the terminal device can execute the reconnection process for the base station device and continue the communication.

Further, the terminal device may notify the user of the information of the base station device selected as described above, for example, through a display screen. For example, the terminal device may display an icon on the screen indicating a communication service that is in an executable state from the viewpoint of wireless quality. Further, the terminal device may indicate a communication service in a state in which it can be executed from the viewpoint of wireless quality by using voice (ring tone or the like) or vibration. In addition, when the terminal device is requested to start the communication service during standby, if the communication service cannot be executed via the selected base station device, a message indicating that the communication service cannot be executed. May be notified to the user by screen display, voice, or the like.

(Device configuration)
FIG. 2 shows a hardware configuration example of the base station apparatus (base station apparatus 101 to base station apparatus 103) and the terminal apparatus according to the present embodiment. In one example, these devices include a processor 201, a ROM 202, a RAM 203, a storage device 204, and a communication circuit 205. The processor 201 is a computer including one or more processing circuits such as a general-purpose CPU (central processing unit) and an ASIC (application specific integrated circuit), and is stored in a ROM 202 or a storage device 204. By reading and executing the existing program, the entire processing of the base station device / terminal device and each of the above-mentioned processes are executed. The ROM 202 is a read-only memory that stores information such as programs and various parameters related to processing executed by the base station device / terminal device. The RAM 203 is a random access memory that functions as a workspace when the processor 201 executes a program and stores temporary information. The storage device 204 is composed of, for example, a detachable external storage device or the like. The communication circuit 205 is composed of, for example, a circuit for wireless communication. The base station device / terminal device includes, for example, a baseband circuit and an RF circuit for cellular communication, and an antenna as a communication circuit 205 for communication with other devices. Although one communication circuit 205 is shown in FIG. 2, the base station device / terminal device may have a plurality of communication circuits. For example, the base station device may have a wired or wireless communication circuit for communication with other base station devices in addition to a communication circuit for communication with the terminal device. Further, the terminal device may have a communication circuit such as a wireless LAN in addition to the communication circuit for communication with the base station device.

FIG. 3 shows an example of the functional configuration of the base station device according to the present embodiment. The base station apparatus includes a communication unit 301, a service notification unit 302, and a request radio quality notification unit 303. Note that these functions may be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204, or may be realized by dedicated hardware. FIG. 3 illustrates the functions related to the method according to the present embodiment, and the base station apparatus naturally has a function as a general base station apparatus.

The communication unit 301 is, for example, a functional unit for executing wireless communication with the terminal device 121. The communication unit 301 executes wireless communication conforming to the 5G cellular communication standard, for example. The communication unit 301 is configured to periodically transmit a broadcast signal (broadcast signal), for example, to notify a terminal device located in a cell formed by the base station device itself of predetermined information. To. Further, the communication unit 301 can shift the terminal device to the connected state and perform data communication by transmitting and receiving a predetermined message to and from the terminal device to be communicated with. Further, the communication unit 301 is configured to send and receive a predetermined message for shifting the terminal device whose communication has ended to the standby state.

The service notification unit 302 is configured to notify the terminal device of information on communication services that can be provided by the base station device itself or another base station device such as an adjacent base station device. Here, the communication services that can be provided can be determined at least based on whether or not each base station apparatus supports a network slice corresponding to each communication service. The service notification unit 302 can notify the terminal device of the communication service that can be provided, for example, by transmitting a signal including explicit identification information (for example, S-NSSAI). Further, the service notification unit 302 prepares, for example, a field for notifying each communication service of the required radio quality in the signal, and implicitly depending on whether or not a valid numerical value is included in the field. It is possible to notify the terminal device of the communication service that can be provided to the terminal device. In this case, it is indicated that the communication service corresponding to the field containing the invalid number cannot be provided. It should be noted that communication services that can be provided in other formats may be indicated. The service notification unit 302 can notify the information by a broadcast signal or an individual signal. If the terminal device knows the communication service that the base station device can provide in advance (for example, from the time of manufacture), the service notification unit 302 may be omitted.

The request radio quality notification unit 303 is the radio quality information required to execute at least one of the information of the communication services that can be provided by the base station device itself or each of the other base station devices such as the adjacent base station device. Is shown. This requested radio quality information may be notified to the terminal device together with information indicating the communication service that can be provided by the service notification unit 302, or may be notified separately. For example, one may be notified by an individual signal and the other may be notified by a broadcast signal. Since the method of notifying the required radio quality information is as described above, it will not be repeated in detail here.

FIG. 4 shows an example of the functional configuration of the terminal device according to the present embodiment. The terminal device includes a communication unit 401, an information acquisition unit 402, and a base station selection unit 403. These functions may be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204, or may be realized by dedicated hardware. Note that FIG. 4 illustrates the functions related to the method according to the present embodiment, and the terminal device naturally has a function as a general terminal device.

The communication unit 401 is, for example, a functional unit for executing wireless communication with a base station device. The communication unit 401 executes wireless communication conforming to the 5G cellular communication standard, for example. The communication unit 401 is configured to receive, for example, a broadcast signal (broadcast signal) periodically transmitted from the base station apparatus and receive predetermined information. Further, when the terminal device itself should perform communication, the communication unit 401 shifts to the connected state by transmitting and receiving a predetermined message to and from the base station device selected in the standby state, and the base station thereof. Can perform data communication with the device. Further, the communication unit 401 is configured to shift to the standby state by transmitting and receiving a predetermined message when the communication is completed. Further, the communication unit 401 detects the radio quality measurement signal (for example, a signal that can be used for radio quality measurement such as a reference signal) transmitted from each base station device to measure the radio quality. It is composed.

The information acquisition unit 402 acquires radio quality information required for a communication service that can be executed by each of the one or more base station devices from at least one of the one or more base station devices. In addition, the information acquisition unit 402 can acquire information on communication services that can be provided by each base station device. If the information acquisition unit 402 knows the communication service that can be provided by each base station device in advance (for example, from the time of manufacture), it is not necessary to acquire the information indicating the communication service.

When the base station selection unit 403 should shift to the connection state based on the information acquired by the information acquisition unit 402 and the radio quality measurement value of the radio signal from the surrounding base station equipment measured by the communication unit 401. Select the base station device to connect to. The base station selection unit 403 should identify a communication service that can be provided by each base station device by, for example, a broadcast signal transmitted from each base station device, and execute the specified communication service by the terminal device itself. Determine if communication services are included. In one example, the base station selection unit 403 may exclude the base station device capable of providing all the communication services that can be executed by the terminal device itself from the selection target at this point. Further, the base station selection unit 403 excludes the base station device capable of providing all the predetermined communication services designated as important from the communication services that can be executed by the terminal device itself from the selection target at this point. May be good. Further, the base station selection unit 403 may leave a base station device that can provide any one of the communication services that the terminal device itself can execute as a selection target at this time. Then, the base station selection unit 403 is transmitted from each base station device with the required radio quality of at least one of the communication services that each base station device can provide from the base station devices remaining as selection target candidates. Based on the measured value of the radio quality obtained by measuring the radio signal, the base station device to be connected when the transition to the connection state should be made is selected. For example, when the base station selection unit 403 can obtain a radio quality exceeding the required radio quality for the base station equipment remaining as the selection target, the base station selection unit 403 selects the base station equipment as the connection destination base station equipment. sell. When there are a plurality of such base station devices, the base station selection unit 403 may select, for example, the base station device capable of obtaining the best measured value of radio quality as the connection destination base station device. Good. Further, the base station selection unit 403 may select, for example, the base station device having the largest difference value between the measured value of the radio quality and the required radio quality as the base station device to be connected. Further, the base station selection unit 403 may select a base station device to be connected in consideration of other factors such as a congestion state, a network load, and a transmission delay.

(Processing flow)
Subsequently, an example of the processing flow executed in the wireless communication system will be outlined with reference to FIG. Since specific examples of each process are as described above, only an outline of the process flow is given here. In this process, a signal including the required radio quality information is received from each base station device for a communication service that can be provided by one or more base station devices including the base station device (S501). As described above, this notification can be executed by any combination of the individual notification to the terminal device in the connected state and the broadcast notification to the plurality of terminal devices by the broadcast signal. That is, FIG. 5 shows an example in which the terminal device acquires information from a plurality of base station devices in parallel, but only the base station device is connected to any of the base station devices. Information may be obtained from.

After that, the terminal device measures the radio signal from each base station device (S502). The radio signal transmitted from each base station device at this time may be any radio signal that can be used for measuring the radio quality. The terminal device may measure the radio quality by the radio signal when receiving the radio signal including the required radio quality information, for example.

The terminal device determines whether or not the communication service to be executed (executable) by the own device is included in the communication service that can be provided by each base station device. Then, the terminal device extracts the base station device capable of providing the communication service to be executed by the terminal device (S503). It should be noted that this determination may not be performed in a predetermined situation such as when each base station device is configured to be able to execute all communication services.

Then, the terminal device extracts the required communication quality of each base station device for the communication service to be executed by the own device (S504), and the measured value of the radio quality obtained in S502 exceeds the extracted required communication quality. The base station device to be connected when the station device should be transferred to the connected state is selected (S505).

In this way, the terminal device selects the base station device that satisfies the required radio quality corresponding to the communication service to be executed by the own device, and therefore, when the execution of the communication service is started, the selected base is selected. By connecting to a station device, the communication service can be promptly provided.

The invention is not limited to the above embodiment, and various modifications and changes can be made within the scope of the gist of the invention.

This application claims priority based on Japanese Patent Application No. 2019-206088 submitted on November 14, 2019, and all the contents thereof are incorporated herein by reference.

Claims

It ’s a terminal device,
An acquisition means for acquiring information indicating the required radio quality for at least one of the one or more communication services that the one or more base station devices can each provide.
A measuring means for measuring radio quality between each of the one or more base station devices,
Based on the communication service that can be executed by the terminal device, the information indicating the radio quality of the communication service, and the measured value of the measured radio quality, the base station device to which the terminal device is connected is described in 1. A selection method to select from one or more base station devices,
Terminal device with.
The terminal device according to claim 1, wherein the acquisition means acquires information indicating the radio quality by a broadcast signal transmitted from at least one of the one or more base station devices.
The acquisition means acquires the values of Qrxlevmin (Minimum required RX level in the cell) and / or Qqualmin (Minimum required quality level in the cell) notified by the system information block (SIB) as information indicating the radio quality. The terminal device according to claim 2.
The acquisition means is an offset corresponding to the difference between the value of Qrxlevmin (Minimum required RX level in the cell) and / or Qqualmin (Minimum required quality level in the cell) notified by the system information block (SIB) and the reference value. The terminal device according to claim 2, wherein the value is acquired as information indicating the radio quality.
The information indicating the radio quality is any one of claims 1 to 4, which is information in which the identification information for identifying the communication service and the quality information indicating the radio quality required for the communication service are associated with each other. The terminal device described in.
The terminal device according to claim 5, wherein a plurality of the identification informations are associated with one piece of the quality information in the information indicating the radio quality.
The terminal device according to claim 5 or 6, wherein the identification information is S-NSSAI (Single-Network Slice Selection Assistance Information).
The terminal device according to any one of claims 1 to 7, wherein the acquisition means separately acquires information indicating the radio quality for each frequency band in which the terminal device can be used.
The acquisition means according to any one of claims 1 to 8, wherein the acquisition means acquires information indicating the radio quality of the one or more base station devices from each of the one or more base station devices. Terminal equipment.
The acquisition means according to any one of claims 1 to 9, wherein the acquisition means acquires information indicating the radio quality of another base station device different from the one base station device from one base station device. Terminal device.
The information indicating the radio quality is associated with the network identifier and
The terminal device according to any one of claims 1 to 10, wherein the acquisition means acquires information indicating the radio quality for each identifier of the network.
The terminal device according to any one of claims 1 to 11, wherein the acquisition means individually acquires information indicating the radio quality common to a plurality of base station devices from a base station device having established a connection.
The acquisition means acquires a communication service that can be provided by each of the one or more base station devices by a broadcast signal.
The selection means identifies a communication service common to a communication service that can be provided by each of the one or more base station devices and a communication service that can be executed by the terminal device, and the said said about the specified communication service. The claim that the base station device to which the terminal device is connected is selected from the one or more base station devices based on the information indicating the radio quality common to the plurality of base station devices and the measured value. 12. The terminal device according to 12.
It ’s a base station device,
A base having a notification means for notifying a terminal device of information indicating required radio quality for at least one of one or more communication services that can be provided by one or more base station devices including the base station device. Station equipment.
The base station device according to claim 14, wherein the notification means notifies information indicating the radio quality by a broadcast signal.
The notification means notifies the value of Qrxlevmin (Minimum required RX level in the cell) and / or Qqualmin (Minimum required quality level in the cell) as information indicating the radio quality by the system information block (SIB). The base station apparatus according to claim 15.
The notification means uses the system information block (SIB) to set the values and reference values of Qrxlevmin (Minimum required RX level in the cell) and / or Qqualmin (Minimum required quality level in the cell) as information indicating the radio quality. The base station apparatus according to claim 15, which notifies an offset value corresponding to the difference between the two.
The information indicating the radio quality is any one of claims 14 to 17, which is information in which the identification information for identifying the communication service and the quality information indicating the radio quality required for the communication service are associated with each other. The base station device described in.
The base station device according to claim 18, wherein the notification means notifies a plurality of the identification information in association with one piece of the quality information in the information indicating the radio quality.
The base station device according to claim 18 or 19, wherein the identification information is S-NSSAI (Single-Network Slice Selection Assistance Information).
The base station device according to any one of claims 14 to 20, wherein the notification means separately notifies information indicating the radio quality for each frequency band.
The base station device according to any one of claims 14 to 21, wherein the notification means notifies information indicating the radio quality of other adjacent base station devices.
The information indicating the radio quality is associated with the network identifier and
The base station apparatus according to any one of claims 14 to 22, wherein the notification means notifies information indicating the radio quality for each identifier of the network.
The base station device according to any one of claims 14 to 23, wherein the notification means individually notifies a connected terminal device of information indicating the radio quality common to a plurality of base station devices.
The base station device according to claim 24, wherein the notification means notifies the communication service that can be provided by the base station device by a broadcast signal.
A control method performed by a terminal device
Acquiring information indicating the required radio quality for at least one of the one or more communication services that one or more base station devices can each provide.
Measuring the radio quality between each of the one or more base station devices and
Based on the communication service that can be executed by the terminal device, the information indicating the radio quality of the communication service, and the measured value of the measured radio quality, the base station device to which the terminal device is connected is described in 1. To choose from more than one base station device
Control methods including.
A control method performed by a base station device,
Control, including notifying the terminal device of information indicating the required radio quality for at least one of the one or more communication services that the one or more base station devices including the base station device can each provide. Method.
To the computer installed in the terminal device
Obtaining information indicating the required radio quality for at least one of the one or more communication services that the one or more base station devices can each provide.
The radio quality between each of the one or more base station devices is measured.
Based on the communication service that can be executed by the terminal device, the information indicating the radio quality of the communication service, and the measured value of the measured radio quality, the base station device to which the terminal device is connected is described in 1. Select from one or more base station devices,
Program for.
On the computer installed in the base station equipment,
A program for causing a terminal device to be notified of information indicating required radio quality for at least one of one or more communication services that can be provided by one or more base station devices including the base station device.