JP6081652B1 - Terminal device, communication system, and connection destination selection method - Google Patents

Abstract

An object of the present invention is to select an appropriate connection destination for an application when switching, adding, or deleting a connection destination. In a base station device, connection destination candidate information relating to a base station device as a connection destination candidate to which the terminal device can be connected is generated, and a control message for connection destination candidate notification including the connection destination candidate information is sent to the terminal device. The base station device to be a new connection destination based on the state of the user application unit that performs information processing requested by the user while communicating with the base station device and the connection destination candidate information. select. [Selection] Figure 3

Description

  The present invention selects a base station device that is a connection destination from a plurality of base station devices and performs wireless communication with the base station device, and a base station device that is a connection destination of terminal devices from a plurality of base station devices And a connection destination selection method for selecting a base station device that is a connection destination of a terminal device from a plurality of base station devices, and a communication system that performs wireless communication between the base station device and the terminal device. is there.

  In recent years, various wireless communication systems such as a mobile communication network such as LTE (Long Term Evolution) and a wireless LAN have become widespread. In terminal devices such as smartphones, a base station of any of these wireless communication systems is appropriately used. In the future, 5G (next generation mobile communication system) will be added, and the options of base stations will be further expanded. In a communication environment in which a plurality of wireless communication methods are mixed, that is, a so-called heterogeneous network, there are a large number of connectable base stations. Therefore, it is required to appropriately select a base station as a connection destination.

  On the other hand, various types of applications are operating on terminal devices, such as those that download data, real-time devices such as voice calls and video distribution, and non-real-time devices such as e-mail. . Depending on the type of application, the required communication conditions (transmission quality, etc.) vary, so when selecting a base station to be connected, the connection destination depends on the application that requires communication. It is required to select a base station to become.

  As a technology related to selecting a base station as a connection destination according to an application requiring communication in this way, conventionally, the connection destination is determined based on communication conditions according to the type of application (e-mail or browser). The technique to select is known (refer patent document 1). In addition, a technique for selecting a communication system based on the type of information service (voice call, e-mail transmission, file download, etc.) used in the terminal device is known (see Patent Document 2).

JP 2002-135824 A Japanese Patent No. 4992977

  However, in the conventional technique disclosed in Patent Document 1, when selecting an initial connection destination at the start of communication in a non-communication terminal device, a connection destination selection process based on communication conditions according to the type of application and the like No consideration is given to processing when switching, adding, or deleting a connection destination in a terminal device in communication with a certain base station.

  Further, in the conventional technique disclosed in Patent Document 2, only a communication system (wireless communication system) is allocated for each type of information service, and a specific base station to be connected is not selected. However, it is merely a selection of a communication system (wireless communication system). Therefore, it is not possible to meet the demand for selecting an appropriate base station for the application.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to select a connection destination suitable for an application when switching, adding, or deleting the connection destination. An object of the present invention is to provide a terminal device, a communication system, and a connection destination selection method configured to be able to select.

  The terminal device of the present invention selects a base station device as a connection destination from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band, A terminal device that performs wireless communication with the base station device, a communication unit that performs wireless communication with the base station device, and a user requests while communicating with the base station device via the communication unit A control unit having a user application unit that performs information processing, and the communication unit transmits connection destination candidate information about the base station device as a connection destination candidate to which the terminal device can be connected, transmitted from the base station device. The control unit receives the control message of the connection destination candidate notification including the connection destination candidate when the remaining communication amount is not less than a predetermined value as the state of the user application unit. The small cell base station apparatus from the complementary information, a configuration for selecting as a new destination.

Further, the communication system according to the present invention provides a base station that is a connection destination of a terminal device from a plurality of base station devices including at least a small cell base station device that uses a high frequency band and a macro cell base station device that uses a UHF band. A communication system that selects a device and performs wireless communication between the base station device and the terminal device, wherein the base station device includes a communication unit that performs wireless communication with the terminal device, and A control unit for generating connection destination candidate information related to the base station device as a connection destination candidate to which the terminal device can be connected;
The communication unit transmits a connection destination candidate notification control message including the connection destination candidate information, and the terminal device performs a wireless communication with the base station device, and the communication unit. A control unit having a user application unit that performs information processing requested by a user while communicating with the base station device via the communication device, the communication unit being transmitted from the base station device, When receiving a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connectable connection destination candidate, the control unit is a sensor system when the type of user of the user application unit is a sensor system Is configured to select the macro cell base station apparatus as a new connection destination from the connection destination candidate information.

  In addition, the connection destination selection method of the present invention includes a base cell serving as a connection destination of a terminal device from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band. A connection destination selection method for selecting a station apparatus, wherein the terminal apparatus includes connection destination candidate information transmitted from the base station apparatus and related to a base station apparatus as a connection destination candidate connectable to the terminal apparatus. When the remaining communication amount is a predetermined value or more as a state of the user application that receives the control message for the destination candidate notification and performs information processing requested by the user while communicating with the base station apparatus, the connection destination candidate information The small cell base station apparatus is selected as a new connection destination.

  ADVANTAGE OF THE INVENTION According to this invention, a connection destination suitable for a user application part can be selected from the base station apparatus selected as a connection destination candidate in a base station apparatus.

Overall configuration diagram of a communication system according to the present embodiment The sequence diagram which shows the procedure of the basic process performed with the terminal device 1, the 1st base station apparatus 2, and the 2nd base station apparatus 3 Sequence diagram showing the procedure for switching the connection destination Sequence diagram showing the procedure for adding a connection destination Sequence diagram showing the procedure for deleting a connection destination The block diagram which shows the hardware constitutions of the terminal device 1 The block diagram which shows the hardware constitutions of the 1st base station apparatus 2 Functional block diagram of the terminal device 1 Functional block diagram of first base station apparatus 2 The flowchart which shows an example of the procedure of the process performed in the connection destination selection part 43 of the terminal device 1.

  A first invention made to solve the above-mentioned problems is a connection destination from a plurality of base station apparatuses including at least a small cell base station apparatus using a high frequency band and a macro cell base station apparatus using a UHF band. A terminal device that selects a base station device and performs wireless communication with the base station device, a communication unit that performs wireless communication with the base station device, and the base station device via the communication unit A control unit having a user application unit that performs information processing requested by the user while performing communication, and the communication unit is transmitted from the base station device as a connection destination candidate to which the terminal device can be connected. A connection destination candidate notification control message including connection destination candidate information related to the base station apparatus is received, and the control unit has a remaining communication amount equal to or greater than a predetermined value as the state of the user application unit In some cases, the small cell base station apparatus from among the connection destination candidate information, and configured to select as a new connection destination.

  According to this, when the remaining communication amount is not less than a predetermined value as the state of the user application unit among the base station devices selected as connection destination candidates in the base station device, the small cell base station device is replaced with a new connection destination. Can be selected. For this reason, when the traffic is large, it is possible to appropriately select a small cell base station apparatus that is a high SHF band cell capable of high-speed communication.

  The second invention selects a base station device to be connected from a plurality of base station devices including at least a small cell base station device that uses a high frequency band and a macro cell base station device that uses a UHF band. A terminal device that performs wireless communication with the base station device, a communication unit that performs wireless communication with the base station device, and a user request while communicating with the base station device via the communication unit And a control unit having a user application unit that performs information processing, and the communication unit is a connection destination candidate related to the base station device that is transmitted from the base station device and that can be connected to the terminal device. The control unit receives a connection destination candidate notification control message including information, and the control unit, when the type of the use subject of the user application unit is a sensor system, the connection destination candidate information. The macrocell base station apparatus from among, a configuration for selecting as a new destination.

  According to this, when the type of the use subject of the user application unit is a sensor system among the base station apparatuses selected as connection destination candidates in the base station apparatus, the macro cell base is selected from the connection destination candidate information. The station device can be selected as a new connection destination. For this reason, if the application user is a sensor system, the amount of communication is small. Therefore, it is not necessary to select a high SHF band cell, and a macro cell base station apparatus can be appropriately selected.

  In addition, according to a third aspect of the present invention, the user application unit is one operating in the foreground among a plurality of user application units operating on the terminal device, one having the highest priority, and communication within a certain period of time. It is set as the structure which is one of the largest quantity.

  According to this, it is possible to appropriately select a base station apparatus as a new connection destination.

  In addition, according to a fourth aspect of the present invention, the connection destination candidate notification control message includes congestion degree information regarding the base station device that is a connection destination candidate, and the control unit performs a new connection based on the congestion degree information. The base station apparatus is selected.

  According to this, it is possible to appropriately select a base station apparatus as a new connection destination.

According to a fifth aspect of the present invention, there is provided the base station device as a connection destination of a terminal device from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band. The base station apparatus and the terminal apparatus, and the base station apparatus includes a communication unit that performs wireless communication with the terminal apparatus, and the terminal. A control unit that generates connection destination candidate information regarding the base station device as a connection destination candidate to which the device can be connected;
The communication unit transmits a connection destination candidate notification control message including the connection destination candidate information, and the terminal device performs a wireless communication with the base station device, and the communication unit. A control unit having a user application unit that performs information processing requested by a user while communicating with the base station device via the communication device, the communication unit being transmitted from the base station device, When receiving a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connectable connection destination candidate, the control unit is a sensor system when the type of user of the user application unit is a sensor system Is configured to select the macro cell base station apparatus as a new connection destination from the connection destination candidate information.

  According to this, similarly to the first invention, it is possible to select an appropriate connection destination for the user application unit.

In addition, the sixth invention relates to the base station device that is a connection destination of a terminal device from a plurality of base station devices including at least a small cell base station device that uses a high frequency band and a macro cell base station device that uses a UHF band. The base station apparatus and the terminal apparatus, and the base station apparatus includes a communication unit that performs wireless communication with the terminal apparatus, and the terminal. A control unit that generates connection destination candidate information regarding the base station device as a connection destination candidate to which the device can be connected;
The communication unit transmits a connection destination candidate notification control message including the connection destination candidate information, and the terminal device performs a wireless communication with the base station device, and the communication unit. A control unit having a user application unit that performs information processing requested by a user while communicating with the base station device via the communication device, the communication unit being transmitted from the base station device, When receiving a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connectable connection destination candidate, the control unit is a sensor system when the type of user of the user application unit is a sensor system Is configured to select the macro cell base station apparatus as a new connection destination from the connection destination candidate information.

  According to this, similarly to the second invention, it is possible to select an appropriate connection destination for the user application unit.

  According to a seventh aspect of the present invention, there is provided a base station device to which a terminal device is connected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band. A connection destination selection method for selecting a connection destination candidate including connection destination candidate information related to a base station device as a connection destination candidate connectable to the terminal device, transmitted from the base station device in the terminal device. When the remaining communication amount is a predetermined value or more as the state of the user application that performs the information processing requested by the user while communicating with the base station apparatus, the control message is received from the connection destination candidate information. The small cell base station apparatus is configured to be selected as a new connection destination.

  According to this, similarly to the first invention, it is possible to select an appropriate connection destination for the user application unit.

  In addition, according to an eighth aspect of the present invention, there is provided a base station device to which a terminal device is connected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band. A connection destination selection method for selecting a connection destination candidate including connection destination candidate information related to a base station device as a connection destination candidate connectable to the terminal device, transmitted from the base station device in the terminal device. When the type of user application user that performs the information processing requested by the user while communicating with the base station apparatus is a sensor system, the macro cell is selected from the connection destination candidate information. A base station apparatus is selected as a new connection destination.

  According to this, similarly to the second invention, it is possible to select an appropriate connection destination for the user application unit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a communication system according to the present embodiment.

  This communication system includes a terminal device 1, a first base station device 2, a second base station device 3, and a third base station device 4 that perform wireless communication with the terminal device 1. This communication system is a so-called heterogeneous network, and the first base station apparatus 2, the second base station apparatus 3, and the third base station apparatus 4 are different in RAT (Radio Access Technology).

  The terminal device 1 is a smartphone, a tablet terminal, or the like, and can communicate with any one or more of the base station devices 2 to 4. Among the plurality of base station devices 2 to 4, Thus, an appropriate connection destination is selected, and communication using the selected base station device is performed by the terminal device 1.

  The first base station apparatus 2 performs wireless communication using a UHF band (frequency: 300 MHz to 3 GHz), as in LTE, among wireless communication systems for mobile phones, and becomes a macro cell base station. The radius is, for example, about 1 km to 25 km. The first base station apparatus 2 serves as a control plane (C-Plane) base station for transmitting control signals.

  The second base station apparatus 3 uses a high frequency band, that is, a high SHF band (frequency: 6 GHz to 30 GHz) or an EHF band (frequency: mainly 30 GHz) as in 5G among wireless communication systems for mobile phones. ˜60 GHz), which is a small cell base station with a cell radius of about 10 m to 3 km, for example. The second base station apparatus 3 serves as a user plane (U-Plane) base station for transmitting user data.

  A plurality of the second base station devices 3 are installed in the communication area of the first base station device 2, and the communication areas of the first base station device 2 and the second base station device 3 overlap. The terminal device 1 can use both the first base station device 2 and the second base station device 3 simultaneously, and can use a plurality of second base station devices 3 simultaneously.

  The first base station device 2 and the second base station device 3 are connected to each other via an X2 interface. The first base station device 2 and the second base station device 3 exchange control messages to perform processing related to addition, switching, and deletion of the connection destination of the terminal device 1. The first base station device 2 and the second base station device 3 are connected to the Internet via the S1 interface and a higher-level core network (higher-level communication network).

  The third base station device 4 is a wireless communication method other than the mobile phone wireless communication method such as the first base station device 2 and the second base station device 3, such as Wi-Fi (registered trademark), Wireless communication is performed with the terminal device 1 by a wireless LAN wireless communication method such as WiGig (registered trademark). The third base station device 4 is connected to the Internet.

  Next, basic procedures performed in the terminal device 1, the first base station device 2, and the second base station device 3 will be described. FIG. 2 is a sequence diagram illustrating a procedure of basic processing performed in the terminal device 1, the first base station device 2, and the second base station device 3.

  The example shown in FIG. 2A is a case where the first base station apparatus 2 that is currently communicating is switched to the first base station apparatus 2 that becomes a new connection destination. In FIG. 2, the first base station device 2 that is currently communicating is referred to as “first base station device (existing)”, and the first base station device 2 that is the switching destination is referred to as “first base station”. "Device (switching destination)".

  In this case, first, the transmission control unit of the terminal device 1 performs wireless quality measurement on the detected first base station device 2 (switching destination), and the wireless quality measurement value (the measurement result) ( A control message of a measurement report (for example, Measurement Report) including received power, S / N, etc. is transmitted to the first base station apparatus 2 currently in communication.

  When receiving the measurement report control message transmitted from the terminal apparatus 1, the first base station apparatus 2 currently in communication performs quality determination based on the radio quality measurement value included in the measurement report, The first base station apparatus 2 is determined. And the control message of a connection request (for example, Handover request) is transmitted to the 1st base station apparatus 2 of a switching destination.

  Upon receiving the connection request control message transmitted from the first base station device 2 that is currently in communication, the first base station device 2 that is the switching destination sends the control message of the confirmation response (for example, Handover request ACK) It transmits to the 1st base station apparatus 2 in communication.

  When the first base station device 2 currently in communication receives the control message of the confirmation response transmitted from the first base station device 2 that is the switching destination, the control message of the switching instruction (for example, Mobility from EUTRA command) is sent. It transmits to the terminal device 1.

  When the terminal device 1 receives the switching instruction control message transmitted from the first base station device 2 that is currently in communication, the terminal device 1 performs a connection destination switching process and sends a control message of switching completion (for example, Handover Complete) to the switching destination. To the first base station apparatus 2. Thereby, the terminal device 1 can start communication with the 1st base station apparatus 2 of a switching destination.

  The example shown in FIG. 2B is a case where a second base station apparatus 3 as a new connection destination is added in addition to the first base station apparatus 2 that is currently communicating.

  In this case, first, the transmission control unit of the terminal device 1 performs wireless quality measurement on the detected second base station device 3, and the wireless quality measurement value (reception power, S / N, etc.) is transmitted to the first base station apparatus 2 that is currently communicating.

  When receiving the measurement report control message transmitted from the terminal device 1, the first base station device 2 currently in communication performs quality determination based on the radio quality measurement value included in the measurement report, 2 base station apparatuses 3 are determined. Then, a control message of a connection request (for example, SCG Addition Indication) is transmitted to the additional second base station apparatus 3.

  When the additional second base station device 3 receives the connection request control message transmitted from the first base station device 2 that is currently communicating with the terminal device 1, the confirmation response (for example, SCG Addition / Modification Request) Is sent to the first base station apparatus 2.

  When the first base station device 2 currently in communication with the terminal device 1 receives the confirmation response control message transmitted from the additional second base station device 3, it controls the addition instruction (for example, RRC Connection Reconfiguration). A message is transmitted to the terminal device 1.

  When the terminal device 1 receives the control message of the addition instruction transmitted from the first base station device 2 that is currently in communication, the terminal device 1 performs connection destination addition processing as described later and completes the addition (for example, RRC Connection Reconfiguration Complete). Is transmitted to the additional second base station apparatus 3. Thereby, the terminal device 1 can start communication between the first base station device 2 currently communicating and the additional second base station device 3.

  In the present embodiment, a connection destination selection control program for exchanging control messages with the first base station apparatus 2 to select a connection destination is incorporated in an individual user application program. Among the user application units realized by executing the application program by the processor, the user application unit that defines the communication conditions of the terminal device 1 is connected to the first base station device 2 as described below. Connection destination selection control (control relating to connection destination switching, connection destination addition, and connection destination deletion) is performed in which control messages are exchanged to select a connection destination.

  In particular, in this embodiment, the user application unit operating in the foreground is a user application unit that defines the communication conditions of the terminal device 1. Note that, regardless of the foreground and background, a user application unit with a high priority may perform connection destination selection control. In this case, the user may set a priority in advance in the user application unit.

  A monitoring application unit that monitors the user application unit may be provided separately from the user application unit, and the monitoring application unit may perform connection destination selection control. In other words, the monitoring application unit may determine the connection destination based on the type and operation status of the user application unit with the user application unit in communication as a monitoring target.

  In this case, the monitoring application unit may monitor the user application unit operating in the foreground. Alternatively, the user may set a priority in the user application unit, and the monitoring application unit may select an application with a high priority as a monitoring target. Alternatively, the user application unit that maximizes the amount of communication within a certain time period may be the monitoring target.

  Next, the procedure in the case of connection destination switching will be described. FIG. 3 is a sequence diagram illustrating a procedure in the case of connection destination switching. The terminal device 1 is divided into an application unit and a transmission control unit. Moreover, as described above, the second base station apparatus 3 is a small cell base station that is installed in the communication area of the first base station apparatus 2 that is a macrocell base station. In the example illustrated in FIG. 3, the terminal device 1 disconnects communication with the second base station device 3 (switching source) that is communicating, and the connection destination is changed to another second base station device 3 ( This is a case of switching to (switching destination).

  In the terminal device 1, the user application unit that is already operating is communicating with the first base station device 2 and the second base station device 3. Here, when another new user application unit is activated, the user application unit determines the communication condition.

  In this communication condition determination, it is determined whether or not the second base station apparatus 3 currently in communication satisfies the communication condition requested by the user application unit. Here, if the second base station apparatus 3 that is currently communicating does not satisfy the communication conditions requested by the user application unit and determines that connection destination switching is necessary, a control message for the candidate request is transmitted. To the first base station apparatus 2 via the unit. On the other hand, if the second base station apparatus 3 currently in communication satisfies the communication conditions requested by the user application unit and determines that there is no need to switch the connection destination, the control message for the candidate request is transmitted. Absent.

  The control message for this candidate request includes connection destination candidate information (connection destination candidate list) relating to the second base station apparatus 3 (switching destination) as a connection destination candidate to which the terminal apparatus 1 can be connected to the first base station apparatus 2. Is what you want.

  Specifically, the control message of this candidate request includes information on necessity of providing connection destination candidate information, information on the use of the user application (mass broadband, mission critical, massive connection, etc.), user type (person, car, Robots, drones, ships, airplanes, balloons, sensors, etc.). Here, the user is a user application user of the terminal device 1, and the user application is used by a person possessing the terminal device 1, or a sensor provided in the terminal device 1 is used, There are cases where a device on which the terminal device 1 is mounted is used. Information regarding the user type may be input in advance by a person using the terminal device 1 or the like.

  Further, in the terminal device 1, the transmission control unit performs radio quality measurement for the detected second base station device 3 (in this case, both the switching source and the switching destination), and the detected second base station device 3 is detected. A control message of a measurement report including radio quality measurement values (reception power, S / N, etc.) for each base station apparatus 3 is transmitted to the first base station apparatus 2.

  In this embodiment, the candidate request control message is transmitted separately from the measurement report control message. However, the information included in the candidate request control message is included in the measurement report control message. May be transmitted. In the measurement report control message, the measurement results for each detected second base station device 3 may be transmitted together, but the measurement results for each detected second base station device 3 are individually controlled. You may make it transmit with a message.

  Next, upon receiving the candidate request control message and the measurement report control message transmitted from the terminal device 1, the first base station device 2 receives the second base station device 3 (in this case, the switching source and the switching destination). The connection destination candidate information (connection destination candidate list) relating to the second base station apparatus 3 to be a connection destination candidate is generated. Then, a connection destination candidate notification control message including the connection destination candidate information is transmitted to the terminal device 1.

  The connection destination candidate notification control message includes information such as RAT, frequency, cell ID, and SSID for each second base station apparatus 3 that is a connection destination candidate. Here, the frequency is a frequency used for communication in the second base station apparatus 3 which is a connection destination candidate. The cell ID and SSID are identifiers for identifying the second base station device 3. Note that RAT and frequency may be omitted.

  Further, supplementary information that can be acquired only by the first base station apparatus 2 may be added to the control message of the connection destination candidate notification. Specifically, information regarding the degree of congestion of communication between the second base station apparatus 3 and the terminal apparatus 1 that are connection destination candidates may be added. The information regarding the degree of congestion includes the number of active users (terminal device 1 connected by RRC (Radio Resource Control)), a radio resource usage rate, and the like. Moreover, you may make it add the information regarding the MEC (Mobile Edge Computing) server connected to the 2nd base station apparatus 3 used as a connection destination candidate. Information about the MEC server includes the presence / absence of a content cache, RTT (Round-Trip Time), and the like. Moreover, you may make it add a predicted throughput value and the positional information on the 2nd base station apparatus 3. FIG.

  Next, when the user application unit of the terminal device 1 receives the connection destination candidate notification control message transmitted from the first base station device 2 via the transmission control unit, the user application unit converts the connection destination candidate notification control message into the connection destination candidate notification control message. Based on the included connection destination candidate information, connection destination selection processing is performed. In this process, an optimum connection destination is selected from the second base station devices 3 listed as connection destination candidates in the connection destination candidate information, and a wireless quality measurement value of the connection destination is acquired. Then, a connection destination switching request control message including the wireless quality measurement value of the connection destination is transmitted to the first base station apparatus 2 via the transmission control unit.

  The control message for the connection destination switching request is for requesting connection with the selected base station of the connection destination, and includes information on the selection result of the connection destination selection process. That is, identification information of the second base station apparatus 3 selected as the connection destination, specifically, information such as RAT, frequency, cell ID, SSID, etc. regarding the second base station apparatus 3 selected as the connection destination, and connection It includes radio quality measurement values (reception power and S / N) that are measurement results of radio quality measurement for the second base station apparatus 3 selected as the destination. Note that RAT and frequency may be omitted.

  Next, when the first base station apparatus 2 receives the control message for the connection destination switching request transmitted from the terminal apparatus 1, the first base station apparatus 2 makes a quality determination regarding the second base station apparatus 3 selected as the connection destination by the terminal apparatus 1. Try again. Here, when the quality satisfies a predetermined condition, the second base station device 3 selected as the connection destination by the terminal device 1 is determined as the connection destination, and the second base station device 3 (switching destination) is determined. A connection request control message is sent to. When a control message for confirmation response transmitted from the second base station apparatus 3 is received, a control message for switching instruction is transmitted to the terminal apparatus 1.

  Next, when the transmission control unit of the terminal device 1 receives the switching instruction control message transmitted from the first base station device 2, the transmission processing unit performs the switching process and completes the switching to the first base station device 2. Send a control message. Thereby, the connection with the selected second base station apparatus 3 as the connection destination is established, and the user application unit operating in the terminal apparatus 1 communicates with the selected second base station apparatus 3 as the connection destination. Can communicate with each other.

  In addition, when the first base station device 2 receives the switching completion control message transmitted from the terminal device 1, the first base station device 2 transmits a disconnection request control message to the switching-source second base station device 3. When the switching-source second base station apparatus 3 receives the disconnection request control message transmitted from the first base station apparatus 2, it performs disconnection processing and sends an acknowledgment control message to the first base station apparatus 2. Send to. Through the above processing, the terminal device 1 is in communication with the first base station device 2 and the second base station device 3 (switch destination).

  Next, a procedure for adding a connection destination will be described. FIG. 4 is a sequence diagram showing a procedure in the case of adding a connection destination. In the example shown in FIG. 4, in addition to the first base station apparatus 2 and the second base station apparatus 3 that are communicating, another second base station apparatus 3 is newly added to the connection destination. It is. In FIG. 4, the second base station apparatus 3 currently in communication is referred to as “second base station apparatus (existing)”, and the second base station apparatus 3 to be added is referred to as “second base station apparatus”. "Device (new)".

  In the case of connection destination addition, it is substantially the same as the case of connection destination switching shown in FIG. 3, but in particular, a control message with the second base station apparatus 3 that disconnects communication shown in FIG. The exchange of (disconnect request, confirmation response) is different in that it is not shown in FIG.

  In addition, in the case of adding a connection destination illustrated in FIG. 4, in the communication condition determination, the second base station apparatus 3 that is currently communicating does not satisfy the communication condition requested by the user application unit, and it is necessary to add a connection destination. If it is determined, the control message for the candidate request is transmitted.

  In addition, in the case of connection destination switching shown in FIG. 3, connection destination switching requests, switching instructions, and switching completion control messages exchanged between the terminal apparatus 1 and the first base station apparatus 2 are shown in FIG. In the case of connection destination addition shown in FIG. 2, the connection destination addition request, the addition instruction, and the addition completion control message are obtained. Note that the content of the control message for the connection destination addition request is the same as the control message for the connection destination switching request.

  In the example shown in FIGS. 3 and 4, the connection destination selection control is started when a new user application unit is activated. However, the connection destination selection control can be started at various timings. it can. For example, when the terminal device 1 transitions from the non-communication state to the communication state, when the user application unit operating in the foreground is changed to the background, or when the priority of the user application unit is changed by the user In addition, connection destination selection control may be started. In addition, a monitoring application unit that monitors the user application unit may be provided separately from the user application unit. In this case, when the user application unit to be monitored by the monitoring application unit is changed, the connection destination selection is performed. Start control.

  Further, the communication condition determination can be omitted when the connection destination selection control is started. For example, in the example illustrated in FIGS. 3 and 4, when a new application unit is activated, a control message for a candidate request may be transmitted to the first base station apparatus 2 without performing communication condition determination. .

  Next, the procedure for deleting a connection destination will be described. FIG. 5 is a sequence diagram showing a procedure in the case of connection destination deletion. Note that the example illustrated in FIG. 5 is a case where communication with the second base station apparatus 3 that is in communication is disconnected and the second base station apparatus 3 is deleted from the connection destination.

  In the terminal device 1, the user application unit that is already operating is communicating with the first base station device 2 and the second base station device 3. Here, the transmission control unit of the terminal device 1 newly detects a second base station device 3 that is different from the second base station device 3 that is currently in communication, and communicates with the second base station device 3. When the connection is completed, connection destination update information is notified to the user application unit.

  Upon receiving the connection destination update information from the transmission control unit, the user application unit of the terminal device 1 performs connection destination scrutiny. This connection destination scrutiny is based on the connection destination update information received from the transmission control unit, and determines whether or not the existing connection destination (base station apparatus currently communicating) is necessary, and reviews the connection destination. . In this connection destination scrutiny, when there is a connection destination more suitable than the existing connection destination in the detected base station devices 2 to 4, it is determined that the existing connection destination is unnecessary, and the existing connection destination is deleted. Decide what to do. Also, when it is determined that an existing connection destination is unnecessary from the viewpoint of saving power consumption, it is determined that the existing connection destination is deleted. Then, a connection destination deletion request control message is transmitted to the first base station apparatus 2 via the transmission control unit.

  This connection destination deletion request control message requests the first base station apparatus 2 to delete the existing connection destination. The identification information of the second base station apparatus 3 that is the connection destination to be deleted, specifically, Includes information such as RAT, frequency, cell ID, and SSID regarding the second base station apparatus 3 to be deleted. Note that RAT and frequency may be omitted.

  When the first base station apparatus 2 receives the connection destination deletion request control message transmitted from the terminal apparatus 1, the first base station apparatus 2 performs connection destination deletion processing and sends the disconnection request control message to the second base station apparatus 3. Send. When receiving the disconnection request control message transmitted from the first base station apparatus 2, the second base station apparatus 3 performs disconnection processing and transmits an acknowledgment control message to the first base station apparatus 2. . When receiving the confirmation response control message transmitted from the second base station device 3, the first base station device 2 transmits a connection destination deletion response control message to the terminal device 1.

  When the user application unit of the terminal device 1 receives the connection destination deletion response control message transmitted from the first base station device 2 via the transmission control unit, the user application unit performs connection destination update processing. In this connection destination update process, the deleted connection destination is deleted from the connection destination list (connection destination information).

  Here, in the example illustrated in FIG. 5, the connection destination scrutiny is performed in response to the detection of the new second base station device 3, but when the user application unit is stopped or in the foreground state When the user application unit of the user and the user application unit in the background state are switched, the connection destination may be examined.

  Such connection destination deletion control is performed when there is a change in the communication status such as the availability of new base station devices 2 to 4 or when the user application unit operating on the terminal device 1 is stopped. When a change occurs in the state of the user application unit, processing for deleting unnecessary connection destinations is performed in order to reconstruct the communication environment to be suitable for a new situation.

  For example, there is a case where link aggregation is performed for a high SHF band line and an LTE line, and the LTE line is used as a backup of the high SHF band line. In this case, when a third base station apparatus 4 of WiGig (registered trademark) is newly detected, a WiGig (registered trademark) line is used as a backup of a high SHF band line rather than an LTE line in terms of capacity. Is more appropriate, the existing LTE line becomes unnecessary.

  At this time, if the LTE line is not deleted as an unnecessary connection destination, the first base station apparatus (control plane base station) 2 may instruct to perform communication on the LTE line. In this case, the terminal apparatus 1, the third base station apparatus 4 of WiGig (registered trademark) cannot be used.

  In the examples shown in FIG. 3 to FIG. 5, an example has been given in which only the first base station device 2 and the second base station device 3 using the mobile phone wireless communication method are targeted. It is also possible to perform connection destination switching, connection destination addition, and connection destination deletion for the third base station apparatus 4 using a wireless communication method other than the wireless communication method for mobile phones.

  By the way, various control messages are transmitted and received between the terminal device 1 and the base station devices 2 to 4 as described above, but the connection destination is changed by this control message (connection destination switching, connection destination addition, or connection destination deletion). May be performed in any one of MAC (Media Access Control), PDCP (Packet Data Convergence Protocol), and TCP (Transmission Control Protocol). In particular, carrier aggregation may be used in MAC, and multipath TCP may be used in TCP. In addition, when changing the connection destination (switching connection destination, adding connection destination, or deleting connection destination), it is preferable to transmit and receive control messages in the RRC (Radio Resource Control) layer.

  Next, the hardware configuration of the terminal device 1 will be described. FIG. 6 is a block diagram illustrating a hardware configuration of the terminal device 1.

  The terminal device 1 includes a processor (control unit) 11, a wireless interface (communication unit) 12, an antenna 13, a memory (work memory) 14, a storage device 15 such as a flash memory and a memory card, and an input / output unit 16. And. The storage device 15 stores a program executed by the processor 11 and the like. The input / output unit 16 includes a display, a speaker, operation keys, and the like.

  Next, the hardware configuration of the first base station apparatus 2 will be described. FIG. 7 is a block diagram illustrating a hardware configuration of the first base station apparatus 2.

  The first base station apparatus 2 includes a processor (control unit) 21, a wireless interface 22, an antenna 23, a memory (work memory) 24, a storage device 25 such as an HDD (Hard Disk Device), and a network interface 26. And.

  The storage device 25 stores a program executed by the processor 21 and the like. The wireless interface 22 and the antenna 23 perform wireless communication with the terminal device 1. The network interface 26 performs communication between the second base station device 3 and the core network.

  The second base station device 3 and the third base station device 4 also have the same hardware configuration as that of the first base station device 2.

  Next, a functional configuration of the terminal device 1 will be described. FIG. 8 is a functional block diagram of the terminal device 1.

  The terminal device 1 includes a user application unit 31 and a transmission control unit 32.

  The transmission control unit 32 includes a communication unit 51, a control message transmission / reception unit 52, a quality measurement unit 53, and a base station detection unit 54. The communication unit 51 includes the wireless interface 12 and the antenna 13 (see FIG. 6). The control message transmission / reception unit 52, the quality measurement unit 53, and the base station detection unit 54 are realized by causing the processor 11 to execute a transmission control program stored in the storage device 15 (see FIG. 6).

  The communication unit 51 communicates with the base station devices 2 to 4.

  The control message transmission / reception unit 52 transmits / receives a control message (measurement report, switching instruction, switching completion, addition instruction, addition completion) to / from the base station devices 2 to 4 via the communication unit 51.

  The quality measurement unit 53 performs radio quality measurement for the base station devices 2 to 4 and acquires radio quality measurement values (reception power, S / N, etc.).

  The base station detection unit 54 detects the base station devices 2 to 4 in which the terminal devices are located based on signals transmitted from the base station devices 2 to 4, and the base station device 2 in which the terminal devices are located. Outputs the connection destination update information for.

  The user application unit 31 includes a control message transmission / reception unit 41, a communication condition determination unit 42, a connection destination selection unit 43, a connection destination examination unit 44, and a connection destination update unit 45. The user application unit 31 is realized by causing the processor 11 to execute an application program stored in the storage device 15 (see FIG. 6).

  In the control message transmission / reception unit 41, control messages (candidate request, connection destination candidate notification, connection destination switching request, connection destination addition request, connection destination deletion request) with the base station devices 2 to 4 via the communication unit 51. Send and receive.

  The communication condition determination unit 42 determines whether the currently communicating base station apparatuses 2 to 4 satisfy the communication condition requested by the user application unit 31. Here, when the currently communicating base station devices 2 to 4 do not satisfy the communication conditions requested by the user application unit 31, it is determined that connection destination switching or connection destination addition is necessary, and the control message transmission / reception unit 41 2, a candidate request control message is generated, and the candidate request control message is transmitted to the base station apparatuses 2 to 4 via the communication unit 51.

  Here, for example, when the user application unit 31 is related to a voice call, the communication condition is that the cell radius is large so that the switching frequency is reduced even at a low speed in order to reduce voice interruption and instantaneous interruption. As required. Further, when the user application unit 31 is related to video viewing (VOD: Video On Demand), a high communication speed is required as a communication condition in order to shorten the download time.

  In addition, when the user application unit 31 is an in-vehicle application application for automatic driving that controls the vehicle, automatic driving control such as braking and steering is performed, so that the vehicle travels to ensure safety. In the middle case, a short delay time is required as a communication condition. On the other hand, when the vehicle is stopped, a high-communication speed is required as a communication condition in order to transmit in real time an image showing a crime situation such as a rough car.

  In addition, when the user application unit 31 is a monitoring camera application whose control target is a monitoring camera, in order to stably notify that an abnormality such as a crime or an accident has not occurred, a normal time when no abnormality is detected The communication condition is required to have high connection stability. On the other hand, when an abnormality is detected, a video showing the crime situation is transmitted in real time, so a high communication speed is required as a communication condition.

  The communication condition determination unit 42 determines the communication condition when the terminal device 1 transitions from the non-communication state to the communication state, and at least one of the cases where the user application unit 31 that defines the communication condition is changed.

  Here, when the user application unit 31 that defines the communication condition is changed, the user application unit 31 operating in the foreground is changed to the background, or the priority of the user application unit 31 is changed by the user. When changed, connection destination selection control may be started. In addition, a monitoring application unit that monitors the user application unit may be provided separately from the user application unit. In this case, when the user application unit to be monitored by the monitoring application unit is changed, the connection destination selection is performed. Start control.

  In the connection destination selection unit 43, based on the connection destination candidate information included in the control message of the connection destination candidate notification acquired from the base station devices 2 to 4, and the connection destination selection policy specified by the user or the application program, Select the destination. When the connection destination is selected by the connection destination selection unit 43, the control message transmission / reception unit 41 generates a control message of the connection destination addition request or the connection destination switching request, and the control message of the connection destination addition request or the connection destination switching request. Is transmitted to the base station apparatuses 2 to 4 via the communication unit 51.

  The connection destination selection unit 43 selects a connection destination based on the type and state of the user application unit 31, the type and state of the user (user) who uses the user application unit 31, the state of the terminal device 1, and the like. . Here, the type of the user application unit 31 relates to whether data is downloaded, whether it is a real-time system (sound or video) or a non-real-time system. The state of the user application unit 31 relates to the remaining communication amount or whether it is a foreground state or a background state. The types of users are people, robots, cars, ships, airplanes, balloons, drones, sensors, and the like. The state of the user is a moving speed, a position, a risk level (near an intersection, etc.), and the like. The state of the terminal device 1 is a battery remaining amount or a heat generation amount.

  Based on the connection destination update information received from the base station detection unit 54, the connection destination scrutiny unit 44 includes the detected base station devices 2 to 4 from the existing connection destination (the base station device currently communicating). When there is an appropriate connection destination, it is determined that the existing connection destination is unnecessary and the existing connection destination is deleted. Also, when it is determined that an existing connection destination is unnecessary from the viewpoint of saving power consumption, it is determined that the existing connection destination is deleted. If it is determined that the existing connection destination is to be deleted, the control message transmitting / receiving unit 41 generates a control message for requesting connection destination deletion, and sends the control message for the connection destination deletion request via the communication unit 51. To base station apparatuses 2-4.

  The connection destination update unit 45 performs an update process for registering the deleted connection destination in the connection destination list after deleting and adding the deleted connection destination from the connection destination list (connection destination information).

  In the present embodiment, when the user application unit 31 detects that it is operating in the foreground, each unit of the user application unit 31 performs the above processing.

  In addition, when conducting a connection destination scrutiny when the user application unit is stopped, a management application unit may be provided separately from the user application unit. In this case, the management application unit includes a connection destination scrutiny unit 44 and a connection destination update unit 45.

  Next, a functional configuration of the first base station apparatus 2 will be described. FIG. 9 is a functional block diagram of the first base station apparatus 2.

  The first base station apparatus 2 includes a communication unit 61, a control message transmission / reception unit 62, a quality determination unit 63, and a connection destination deletion unit 64. The communication unit 61 includes the wireless interface 22, the antenna 23, and the network interface 26 (see FIG. 7). The control message transmission / reception unit 62, the quality determination unit 63, and the connection destination deletion unit 64 are realized by causing the processor 21 (see FIG. 7) to execute the transmission control program stored in the storage device 25.

  The communication unit 61 performs communication between the terminal device 1 and the second base station device 3.

  The control message transmission / reception unit 62 transmits / receives a control message between the terminal device 1 and the second base station device 3. Specifically, a candidate request, a measurement report, a connection destination switching request, a connection destination addition request, a switching completion, an addition completion, and a connection destination deletion request transmitted from the terminal device 1 are received, a connection destination candidate notification, a switching instruction, An addition instruction and a connection destination deletion response are transmitted to the terminal device 1. In addition, the connection request and the disconnection request are transmitted to the second base station apparatus 3 and the confirmation response transmitted from the second base station apparatus 3 is received.

  When the quality determination unit 63 receives the candidate request and the measurement report transmitted from the terminal device 1 by the control message transmission / reception unit, the quality determination unit 63 collects the communication quality information for each second base station device 3 included in the measurement report and the own device. Based on the information related to the second base station device 3, the quality determination related to the second base station device 3 is performed, and the connection destination related to the second base station device 3 that is a connection destination candidate to which the terminal device 1 can be connected. Candidate information (connection destination candidate list) is generated. When the connection destination candidate information is generated by the quality determination unit 63, the control message transmission / reception unit 62 generates a connection destination candidate notification control message including the connection destination candidate information, and sends the connection destination candidate notification control message to the terminal device. 1 to send.

  When the connection destination switching request or the connection destination addition request control message transmitted from the terminal device 1 is received by the control message transmission / reception unit 62, the connection destination deletion unit 64 performs processing for deleting the connection destination.

  Next, processing performed by the connection destination selection unit 43 of the terminal device 1 will be described. FIG. 10 is a flowchart illustrating an example of a procedure of processing performed by the connection destination selection unit 43 of the terminal device 1.

  Since the high SHF band cell (first base station apparatus 2) can perform high-speed communication (10 Gbps or more), the high SHF band cell is suitable when the amount of download and communication is large. On the other hand, if the application user is a sensor system, the amount of communication is small, so there is no need to select a high SHF band cell. In addition, since the communication area is small in the high SHF band cell, if the moving speed of the terminal device 1 is high, it passes through the communication area in a short time, so the high SHF band cell is inappropriate. Further, in the high SHF band cell, since the power consumption is large due to the use of a high-frequency circuit and the necessity of simultaneous connection of a backup line because it is weak against shielding and has a high cutting rate, the remaining battery level of the terminal device 1 When there are few, a high SHF band cell is unsuitable.

  Therefore, in the present embodiment, the connection destination selection unit 43 of the terminal device 1 determines whether or not the application is of a type for downloading data (ST101), and the remaining communication amount of the application is a predetermined threshold. A determination as to whether or not the value exceeds (ST102), a determination as to whether or not the user of the application is a person (ST103), and a determination as to whether or not the moving speed of the terminal device 1 is lower than a predetermined threshold value (ST103). ST104) and determination (ST105) of whether or not the remaining battery level of the terminal device 1 exceeds a predetermined threshold value are sequentially performed.

  When the application is of a type that downloads data (Yes in ST101) and the remaining communication amount of the application exceeds a predetermined threshold (Yes in ST102), the user of the application is a person (in ST103). Yes), when the moving speed of the terminal device is lower than a predetermined threshold (Yes in ST104), and the remaining battery level of the terminal device exceeds the predetermined threshold (Yes in ST105), the high SHF band cell In other cases (No in ST101 to ST105), other RAT cells (for example, the second base station apparatus 3 of LTE) are selected as connection destinations (ST107).

  The connection destination selection procedure is not limited to this, and various other procedures are possible.

  As described above, the embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, and the like have been performed. Moreover, it is also possible to combine each component demonstrated by said embodiment into a new embodiment.

  The terminal device, the communication system, and the connection destination selection method according to the present invention have an effect of selecting an appropriate connection destination for an application when switching, adding, or deleting a connection destination, and a plurality of base stations Select a base station device as a connection destination from the device, perform a wireless communication with the base station device, select a base station device as a connection destination of the terminal device from a plurality of base station devices, and select the base station device The present invention is useful as a communication system that performs wireless communication between a device and a terminal device, and a connection destination selection method that selects a base station device that is a connection destination of a terminal device from a plurality of base station devices.

DESCRIPTION OF SYMBOLS 1 Terminal device 2 1st base station apparatus 3 2nd base station apparatus 4 3rd base station apparatus 11 Processor (control part)
21 Processor (control unit)
31 User Application Unit 32 Transmission Control Unit 41 Control Message Transmission / Reception Unit 42 Communication Condition Determination Unit 43 Connection Destination Selection Unit 44 Connection Destination Examination Unit 45 Connection Destination Update Unit 51 Communication Unit 52 Control Message Transmission / Reception Unit 53 Quality Measurement Unit 54 Base Station Detection Unit 61 Communication Unit 62 Control Message Transmission / Reception Unit 63 Quality Determination Unit 64 Connection Destination Delete Unit

Claims (8)

A base station device as a connection destination is selected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band, and wireless communication with the base station device is performed. A terminal device for performing
A communication unit that performs wireless communication with the base station device;
A control unit having a user application unit that performs information processing requested by the user while communicating with the base station device via the communication unit;
With
The communication unit receives a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connection destination candidate connectable to the terminal device, transmitted from the base station device,
When the remaining communication amount is a predetermined value or more as the state of the user application unit, the control unit selects the small cell base station device from the connection destination candidate information as a new connection destination. Characteristic terminal device. A base station device as a connection destination is selected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band, and wireless communication with the base station device is performed. A terminal device for performing
A communication unit that performs wireless communication with the base station device;
A control unit having a user application unit that performs information processing requested by the user while communicating with the base station device via the communication unit;
With
The communication unit receives a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connection destination candidate connectable to the terminal device, transmitted from the base station device,
The control unit selects the macro cell base station apparatus as a new connection destination from the connection destination candidate information when the type of the use subject of the user application unit is a sensor system. Terminal device.   The user application unit is one of a plurality of user application units operating in the terminal device, one operating in the foreground, one having the highest priority, or one having the largest amount of communication within a certain period of time. The terminal device according to claim 1, wherein the terminal device is a terminal device. The control message of the connection destination candidate notification includes congestion degree information regarding the base station device that is a connection destination candidate,
The terminal apparatus according to claim 1, wherein the control unit selects the base station apparatus as a new connection destination in consideration of the congestion degree information. The base station is selected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band, and the base station device is connected to the terminal device. A communication system for performing wireless communication between a device and the terminal device,
The base station device
A communication unit that performs wireless communication with the terminal device;
A control unit that generates connection destination candidate information related to the base station device as a connection destination candidate to which the terminal device can be connected;
With
The communication unit transmits a connection destination candidate notification control message including the connection destination candidate information,
The terminal device
A communication unit that performs wireless communication with the base station device;
A control unit having a user application unit that performs information processing requested by the user while communicating with the base station device via the communication unit;
With
The communication unit receives a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connection destination candidate connectable to the terminal device, transmitted from the base station device,
When the remaining communication amount is a predetermined value or more as the state of the user application unit, the control unit selects the small cell base station device from the connection destination candidate information as a new connection destination. A featured communication system. The base station is selected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band, and the base station device is connected to the terminal device. A communication system for performing wireless communication between a device and the terminal device,
The base station device
A communication unit that performs wireless communication with the terminal device;
A control unit that generates connection destination candidate information related to the base station device as a connection destination candidate to which the terminal device can be connected;
With
The communication unit transmits a connection destination candidate notification control message including the connection destination candidate information,
The terminal device
A communication unit that performs wireless communication with the base station device;
A control unit having a user application unit that performs information processing requested by the user while communicating with the base station device via the communication unit;
With
The communication unit receives a connection destination candidate notification control message including connection destination candidate information related to a base station device as a connection destination candidate connectable to the terminal device, transmitted from the base station device,
The control unit selects the macro cell base station apparatus as a new connection destination from the connection destination candidate information when the type of the use subject of the user application unit is a sensor system. Communications system. A connection destination selection method for selecting a base station device to which a terminal device is connected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band. And
In the terminal device,
A connection destination candidate notification control message including connection destination candidate information related to a base station device as a connection destination candidate to which the terminal device can be connected is transmitted from the base station device, and
When a remaining communication amount is a predetermined value or more as a state of a user application that performs information processing requested by a user while communicating with the base station device, the small cell base station device is selected from the connection destination candidate information. And selecting a connection destination as a new connection destination. A connection destination selection method for selecting a base station device to which a terminal device is connected from a plurality of base station devices including at least a small cell base station device using a high frequency band and a macro cell base station device using a UHF band. And
In the terminal device,
A connection destination candidate notification control message including connection destination candidate information related to a base station device as a connection destination candidate to which the terminal device can be connected is transmitted from the base station device, and
If the type of user application user that performs information processing requested by the user while communicating with the base station device is a sensor system, the macro cell base station device is newly selected from the connection destination candidate information. A connection destination selection method characterized by selecting as a connection destination.

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