Wireless communication system and wireless communication method

Abstract

To provide a communication technology which does not need to switch VPN connection even when a mobile station moves and the destination of a ground station side application is switched.SOLUTION: In the radio communication system / radio communication method for performing communication between a ground station and a mobile station by using radio, the ground station is arranged between a ground station side VPN management device and a mobile station side VPN management device, and VPN connection is performed between the ground station side VPN management device and the mobile station side VPN management device. A unique number (ID) of a mobile station side device or at least one of position information and time information is used to specify an application device of a ground station side being a transmission reception opposite party of data without switching a connection destination of VPN connection or establishing re-connection attended with movement of a mobile station.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a wireless communication system and a wireless communication method that realizes communication with a ground station side application device that supports distributed processing, without causing VPN connection switching even when a mobile station moves, between systems that establish a VPN connection by establishing a VPN tunnel on a communication path. [Background technology]

[0002] In a wireless communication system connecting a ground station and a mobile station, an application on the ground station side (generally a server-side application) and an application on the mobile station side (generally a client-side application) exchange data to operate the application. For example, downloading and playing video data from a video server using a smartphone is achieved through this type of operation.

[0003] In railway communication systems, train control is performed by exchanging control data and the like through communication between devices such as between trains and ground control devices, and between ground central control devices and ground field devices. For example, in a CBTC (Communication Based Train Control) system that uses wireless communication to control trains, train control is achieved by sending and receiving information necessary for train control between the train and a ground control device.

[0004] Various wireless systems are used when exchanging data between mobile station and base station applications, but when using a public wireless network, the wireless system may be shared by an unspecified number of users.

[0005] When utilizing such a shared wireless system, it is important to take security measures such as ensuring confidentiality of communication data between applications on the ground station side and applications on the mobile station side, preventing spoofing and tampering.For this reason, when utilizing a public wireless network, it is common to connect communication paths, including wireless communication paths, with a VPN (Virtual Private Network), and encapsulate and exchange data payloads between applications on the ground station side and applications on the mobile station side in a VPN tunnel.

[0006] Therefore, when applying communications that use a VPN connection to enhance security, it is assumed that the VPN connection is established before exchanging data payloads.

[0007] As a method for maintaining a wireless communication connection without affecting the movement of a mobile station, Patent Document 1 discloses the following technique. To achieve mobility transparency in upper layers, the terminal device 1 acquires the network prefix of the network to which it is currently connected. It then determines whether it is the same as the initial network prefix, and if it is different, it reads the network prefixes of the destination address and source address of the received packet. If the read network prefix is ​​different from the initial network prefix, it replaces it with the initial network prefix to generate a pseudo-header. The terminal device 1 then authenticates the received packet using the generated pseudo-header. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-217951 Summary of the Invention [Problem to be solved by the invention]

[0009] In recent years, applications on the ground station side are sometimes distributed to multiple devices in order to reduce the processing load on each device. For example, in the CBTC system described above, the ground station application exchanges data with ground station application 1 for trains located within a certain section a, and with ground station application 2 for trains located within a certain section b. The processing of the ground station application is distributed by dividing and defining the control responsibility area of ​​the ground station application. In this case, the mobile station application installed on the train must initially receive and send data with ground station application 1 while the train is on the track in section a, and then receive and send data with ground station application 2 when the train moves to section b as it travels.

[0010] In this way, when the terrestrial station application is distributed across multiple devices, the mobile station application must select the appropriate terrestrial station application as the data destination and receive data. However, when the destination of the terrestrial station application changes as the mobile station moves, the destination must be changed, and the VPN connection with the new application that is receiving and transmitting data must be changed and re-established. As a result, data payloads cannot be sent or received while the VPN connection is being changed.

[0011] However, the technology disclosed in the above-mentioned Patent Document 1 does not consider the issues that arise when a VPN connection is used when utilizing a public wireless network, nor does it consider the issues that arise when the processing of an application device on the ground station is distributed to multiple devices.

[0012] Therefore, an object of the present invention is to provide a communication technology that does not require switching of a VPN connection even when a mobile station moves and the destination of a terrestrial station-side application is changed. [Means for solving the problem]

[0013] In order to solve the above-mentioned problems, one representative wireless communication system of the present invention is a wireless communication system connecting a terrestrial station side application device and a mobile station side application device, A ground station side VPN connection management device and a mobile station side VPN connection management device are provided between the ground station side application device and the mobile station side application device, and VPN (Virtual Private Network) connection management is performed in the ground station side communication VPN connection management device and the mobile station side VPN connection management device, Even if the terrestrial station side application device connected to the mobile station side application device is changed, communication can be continued without disconnecting the VPN. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a communication technique that does not require switching of a VPN connection even when a mobile station moves and the destination of a terrestrial station-side application is changed. Problems, configurations, and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an example of a wireless communication system of a railway system when a VPN connection management device is not used. [Figure 2] FIG. 2 is a diagram illustrating an example of a configuration of a wireless communication system according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example in which the wireless communication system according to the first embodiment is applied to a railway system. [Figure 4] FIG. 4 is a diagram illustrating an example of a configuration of a wireless communication system according to the second embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example in which the wireless communication system according to the second embodiment is applied to a railway system. [Figure 6]6 is a diagram illustrating an example of the configuration of a wireless communication system according to a third embodiment, in which a plurality of terrestrial station-side wireless repeaters are provided and a plurality of VPNs are simultaneously connected between the terrestrial station side and the mobile station side. [Figure 7] FIG. 7 is a diagram illustrating an example of a configuration of a wireless communication system according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the technology underlying this disclosure and embodiments for carrying out the invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals.

[0017] In this disclosure, "VPN connection management" refers to a series of connection procedures related to VPN, including authentication and encryption. In addition, "VPN connection management devices" include devices such as VPN gateways, VPN routers, and communication repeaters that are capable of managing the above-mentioned VPN connections.

[0018] First, with reference to FIG. 1, a radio communication system for a railway system that connects a mobile station application device and a plurality of ground station application devices without using a VPN connection management device will be described. In Figure 1, the application device on the ground station side is composed of multiple devices with divided control range sections, such as application device (ground station side) A-1 (101) and application device (ground station side) A-2 (102), in order to distribute processing. The application device (ground station side) A-1 (101) and the application device (ground station side) A-2 (102) are responsible for trains located in the control range section a and the control section b, respectively.

[0019] Therefore, the application device (ground station side) A-1 (101) communicates with the mobile station 107 of the train 1 (205) located in the control range section a via the communication network 1 (401) using the ground station 1 (202) that covers the control range section a as its communication area. Also, the application device (ground station side) A-2 (102) communicates with the mobile station 107 of the train 1 (205) located in the control range section b via the communication network 1 (401) using the ground station 2 (203) that covers the control range section b as its communication area.

[0020] This allows the application device (ground station side) A-1 (101) to establish a VPN connection with the application device (mobile station side) A (109) of train 1 (205) and receive and transmit data. Similarly, the application device (ground station side) A-2 (102) can also establish a VPN connection with the application device (mobile station side) A (109) of train 1 (205) that has moved into control section b while traveling, and receive and transmit data.

[0021] However, in the wireless communication system shown in Fig. 1, at the boundary of the control range, the application device (mobile station side) A (109) needs to switch the destination of the VPN connection from the application device (terrestrial station side) A-1 (101) to the application device (terrestrial station side) A-2 (102). For this reason, it is necessary to temporarily interrupt the VPN connection with the application device (terrestrial station side) A-1 (101), authenticate with the application device (terrestrial station side) A-2 (102), and re-establish the VPN connection. For this reason, there is a period during which data payload cannot be received or transmitted, from the time the VPN connection with the application device (terrestrial station side) A-1 (101) is interrupted until the VPN connection with the application device (terrestrial station side) A-2 (102) is re-established. As train speeds continue to increase, railway systems have become mission-critical systems, and communication downtime is a major problem. Therefore, there is a demand for wireless communication systems that ensure security while also ensuring stable mobility. [Example]

[0022] Next, with reference to FIG. 2, an example of a configuration of a wireless communication system and a wireless communication method according to the first embodiment will be described. FIG. 2 is a diagram illustrating an example of a wireless communication system and a wireless communication method according to the first embodiment. In the following description, the same or equivalent components as those described with reference to FIG. 1 are denoted by the same reference numerals, and the description thereof will be simplified or omitted. Also, in FIG. 2, the ground station side VPN management device (105) is shown as being directly connected to the ground station (106) via a network, but this connection is not necessarily limited to a direct connection, and the ground station and the ground station side VPN management device may be connected via various wired networks or wireless networks.

[0023] Figure 2 shows an example of a configuration in which there are two applications, application device A and application device B, and control data and information are exchanged between the terrestrial station-side device and mobile station-side device of the application. In a typical example, the terrestrial station-side application is generally expressed as the server side, and the mobile station-side application as the client side.

[0024] For distributed processing, application device A and application device B on the ground station side are each composed of multiple devices, such as application device (ground station side) A-1 (101), application device (ground station side) A-2 (102), application device (ground station side) B-1 (103), and application device (ground station side) B-2 (104). Application device (mobile station side) A (109) exchanges data with application device (ground station side) A-1 (101) and / or application device (ground station side) A-2 (102). Similarly, application device (mobile station side) B (110) exchanges data with application device (ground station side) B-1 (103) and / or application device (ground station side) B-2 (104).

[0025] Data is exchanged between the ground station (106) and the mobile station (107) via wireless communication. The type of wireless communication used is not limited, and may be a specially designed proprietary wireless network, a private wireless network using Wi-Fi, or a public wireless network such as a mobile line.

[0026] In the first embodiment, a VPN connection is established over a communication path including a wireless communication path for the purpose of security measures such as ensuring confidentiality of data in wireless communication, preventing spoofing, and preventing tampering. However, in the first embodiment, instead of establishing individual VPN tunnels between the application devices (ground station side) (101-104) and the application devices (mobile station side) (109, 110), a ground station side VPN management device (105) and a mobile station side VPN management device (108) are prepared, and a VPN connection is established between these VPN management devices. This eliminates the need for VPN management on the application device side.

[0027] Furthermore, in the first embodiment, when there are multiple application devices such as application device (ground station side) A-1 (101) and application device (ground station side) A-2 (102) for processing distribution, even if application device (mobile station side) A (109) initially exchanges data with application device (ground station side) A-1 (101) and then switches communication with application device (ground station side) A-2 (102) due to some change in conditions, there is no need to switch the VPN connection. In other words, it is possible to reduce the communication downtime between the application devices due to the VPN connection switching to zero.

[0028] In the first embodiment, the ground station VPN management device (105) is placed between the ground station (106) and the application devices (ground station side) (101 to 104). Any form of communication may be used between the ground station VPN management device (105) and the application devices (ground station side) (101 to 104). However, since the VPN connection is terminated between the ground station VPN management device (105) and the mobile station VPN management device (108), it is desirable to use a means that does not pose a security threat, such as a local network, a private network, or a dedicated communication line.

[0029] Similarly, the mobile station VPN management device (108) is placed between the mobile station (107) and the application devices (mobile station side) (109-110). Any form of communication may be used between the mobile station VPN management device (108) and the application devices (mobile station side) (109-110), but it is desirable to use a means that does not pose a security threat, just as in the case of the ground station side.

[0030] In a configuration in which a VPN connection is terminated between a ground station VPN management device (105) and a mobile station VPN management device (108), and in which a plurality of application devices (ground station side) (101-104) exist for distributed processing, a destination determination unit for determining a receiving device is required. In the first embodiment, a destination selection control unit (111) is provided as a destination determination unit in the application devices (mobile station side) (109-110), and the destination application device (ground station) is selected. In this case, the destination can be selected using information specific to the mobile station device, such as location information, device specific number (ID information), or time / time information.

[0031] The following describes in detail the case where data is exchanged between the application device (ground station side) A (101-102) and the application device (mobile station side) A (109) and application control is performed. When application device (mobile station side) A (109) is located in a control section a, application device (terrestrial station side) A-1 (101) sets application device (mobile station side) A (109) as the control target. When application device (mobile station side) A (109) is located in a control section b, application device (terrestrial station side) A-2 (102) sets application device (mobile station side) A (109) as the control target. A case where processing distribution according to the location of a mobile station side application is performed in this manner will be described.

[0032] In such a case, the destination selection control unit 111 of the application device (mobile station side) A 109 can use, for example, location information of the mobile station side device as information specific to the device itself as management information for destination selection.The destination selection control unit 111 has physical ranges related to the location information of section a and physical ranges related to the location information of section b registered in advance in an internal database as information for selecting a destination. When the location information of the device itself is used as information for destination selection, the destination of the transmission data is selected from application device (terrestrial station side) A-1 (101) or application device (terrestrial station side) A-2 (102) according to the location information of the device itself. That is, by referring to the physical range related to the location of section a and the physical range related to the location of section b registered in the destination selection control unit (111), the destination is selected from application device (terrestrial station side) A-1 (101) or application device (terrestrial station side) A-2 (102). When selecting the destination, by referring to this database, it is possible to extract whether the destination corresponds to section a or section b based on the location information of an arbitrary position, and the application device (terrestrial station) to be the destination can be determined based on the extraction result.

[0033] Various types of identification information can be used to deliver the data payload to the destination selected using the above method, but information that can identify the destination, such as the destination address and port number on the network or the ground station equipment number, can be used. Note that there are various methods for obtaining the location information of the device itself, such as using satellite information from GPS or the like, or the accumulated position movement value obtained from a rotary encoder or the like from a specific position origin, and the method is not limited thereto.

[0034] (Example 1 applied to railways) Next, an example in which the wireless communication system of the first embodiment is applied to a railway system will be described with reference to Fig. 3. In this case, the mobile station side is a railway train, which moves from moment to moment and transmits and receives data to and from a ground station. FIG. 3 is a diagram illustrating an example in which the wireless communication system according to the first embodiment is applied to a railway system. 3, application device A-1 (ground station side) (101) and application device (ground station side) A-2 (102) are configured to be connected to a ground station side VPN management device (105) via communication network 1 (401). Furthermore, the ground station side VPN management device (105) is connected via communication network 2 (402) to both ground station 1 (202) which covers section a as its communication area and ground station 2 (203) which covers section b as its communication area. Therefore, even if the train position changes, the VPN connection between the ground station side VPN management device (105) and the mobile station side VPN management device (106) can be maintained.

[0035] In the configuration of FIG. 3, the application device (ground station side) A-1 (101) controls train 1 (205) when it is located in section a, and the application device (ground station side) A-2 (101) controls train 1 (205) when it is located in section b. To achieve this relationship, the application device (mobile station side) A (110) of train 1 (205) is provided with a destination selection control unit (111). In the destination selection control unit (111), train 1 (205) uses its own train's location information as management information for destination selection, and when train 1 (205) is located in section a, it sets the destination of transmission data to application device (ground station side) A-1 (101). Furthermore, when train 1 (205) is located in section b as it moves, it selects application device (ground station side) A-2 (102) as the destination of data transmission. In this way, application device (mobile station side) A (110) switches the transmission destination depending on the train position, so that communication with each application device (ground station side) (101-102) that supports distributed processing can be switched depending on the position of the mobile station side device while maintaining one VPN connection.

[0036] Next, referring again to FIG. 2, a situation in which data is exchanged between the application device (ground station side) B (103-104) and the application device (mobile station side) B (110) and application control is performed will be described. The application device (ground station side) B-1 (103) and the application device (ground station side) B-2 (104) control an application device (mobile station side) B (110) having a specific device unique number (ID information), thereby distributing processing according to the device unique number (ID information) of the mobile station side application. In this embodiment, the application device (ground station side) B-1 (103) controls application devices (mobile station side) having device unique numbers (ID information) in the range of 1 to 10, and the application device (ground station side) B-2 (104) controls application devices (mobile station side) having device unique numbers (ID information) in the range of 11 to 20.

[0037] In this case, the destination selection control unit (111) of the application device (mobile station side) B (110) uses its own device's unique number (ID information) as management information for destination selection, and then selects the destination of the transmission data from either the application device (terrestrial station side) B-1 (103) or the application device (terrestrial station side) B-2 (104) according to the unique number (ID information) of its own device. In the destination selection control unit (111), application devices (ground station side) that will be destinations corresponding to the device's unique number (ID information) are registered in advance in an internal database as information for selecting a destination. Therefore, when selecting a destination, by referring to this database, it is possible to identify the application device (ground station side) that will be the destination corresponding to the unique number (ID information) of any device, and based on the identification result, it is possible to determine the application device (ground station) that will be the destination. For example, if the device-specific number (ID information) of application device (mobile station side) B (110) is 4, the application device (terrestrial station side) that is the transmission destination is identified as application device (terrestrial station side) B-1 (103) by the above-mentioned method, and the transmission destination is determined.

[0038] Although the application device (ground station side) is not shown in FIG. 2, it is possible to provide a destination selection control unit (111) in the application device (ground station side), and the application device (ground station side) can identify the application device (ground station side) that is the destination of transmission based on the time and time information transmitted by the mobile station side. The method of identification in this case is the same as when identification is made by device unique number (ID information), and it is sufficient to register in advance the application device (ground station side) that will be the transmission destination corresponding to the time / time information in a database inside the destination selection control unit. When selecting a destination, by referring to this database, it is possible to identify the application device (ground station side) that is the transmission destination corresponding to any time / time.

[0039] Although FIGS. 2 and 3 show an example in which the application device (ground station side) distributes processing among two devices, the method of selecting a destination is the same when the processing is distributed among three or more devices.

[0040] As a result, the destination selection control unit (111) of the application device (mobile station side) (109-110) can select the application device (terrestrial station side) (101-104) to be the transmission destination. Conversely, when transmitting data from the application device (ground station side) (101-104) to the application device (mobile station) (109-110), the data may be sent back to the application device (mobile station) (109-110) that sent the data, or a destination selection control unit may be provided in the application device (ground station side) as described in this embodiment.

[0041] (Effects of Example 1) In the wireless communication system and method of the first embodiment, a ground station VPN management device and a mobile station VPN management device are installed between a ground station application and a mobile station application. Therefore, by establishing a VPN connection between the VPN management devices, a wireless communication system is realized that does not require a direct VPN connection between applications and does not require switching of VPN connections on the application side when switching a ground station application. As a result, by managing VPN connections between the ground station VPN management device and the mobile station VPN management device, VPN tunnel management for each application is not required, and communication downtime due to VPN reconnections can be reduced to zero. [Example]

[0042] Next, a wireless communication system and a wireless communication method according to a second embodiment will be described with reference to FIG. 4 is a diagram illustrating an example of a communication configuration to which a wireless communication system and a wireless communication method according to Example 2 are applied. Here, the ground station-side VPN management device is shown as being directly connected to the ground station via a network, but similar to Example 1, instead of a direct connection, the ground station and the ground station-side VPN management device may be connected via various wired networks or wireless networks.

[0043] The second embodiment differs from the first embodiment in that the application devices (mobile station side) (109-110) do not have a destination selection control unit, but the application devices (terrestrial station side) (101-104) have a reception selection control unit (301) as a destination determination unit. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and their description will be simplified or omitted.

[0044] In the wireless communication system and wireless communication method of the second embodiment, the application devices (mobile station side) (109-110) do not have a destination selection control unit 111, and therefore do not specify the application devices (terrestrial station side) (101-104) that are the transmission destinations, and always transmit data to all terrestrial station side devices of the same application. For example, the application device (mobile station side) A (109) always transmits data to both the application device (terrestrial station side) A-1 (101) and the application device (terrestrial station side) A-2 (102).

[0045] The application device (ground station side) always receives data from all application devices (mobile station side), but in order to distribute processing, it needs to determine whether the data is to be controlled by its own application device (ground station side). This determination is made by the reception selection control unit (301), and only when it is determined that the data is to be controlled by its own device, the received data is adopted and application control is performed. In the case of data from a mobile station side application device that its own device should not control, the reception selection control unit (301) discards the data and does not use it for control.

[0046] The reception selection control unit (301) determines whether reception is necessary based on the location information, unique number (ID information), or time / time information of the application device (mobile station side), but this information is stored in the header or payload of the data received from the application device (mobile station side), and the determination can be made by referring to that data. When making the determination based on time / time information, even if the received data does not contain time / time information, the time / time information held by the application device (terrestrial station side) may be used to determine whether reception is necessary.

[0047] FIG. 4 shows an example in which application device (ground station side) A (101-102) distributes processing according to the location of application device (mobile station side) A (109), and application device (ground station side) B (103-104) distributes processing according to the unique number (ID information) of application device (mobile station side) B (110).

[0048] The reception selection control unit (301) can compare the location information, unique number (ID information), and time / hour information contained in the information received from the application device (mobile station side) and the information held by the application device (terrestrial station side) with the information registered in the database within the reception selection control unit (301), and determine whether reception is necessary.

[0049] For example, in the case of application device A, the reception selection control unit (301) decides to use the location information of application device (mobile station side) A (109) as management information for reception necessity, and registers in advance in an internal database the physical range of section a for application device (terrestrial station side) A-1 (101) and the physical range of section b for application device (terrestrial station side) A-2 (102). The reception selection control unit (301) compares the location information included in the information transmitted by application device (mobile station side) A (109) with the range of section a (or section b), and can determine whether its own device needs to receive.

[0050] (Example 2 applied to railways) Next, an example in which the wireless communication system of the second embodiment is applied to a railway system will be described with reference to Fig. 5. In this case, the mobile station side is a railway train, which moves from moment to moment and transmits and receives data to and from a ground station. FIG. 5 is a diagram illustrating an example in which the wireless communication system according to the second embodiment is applied to a railway system. Fig. 5 shows a specific example of data reception selection control according to location information. In the example shown in the figure, a reception selection control unit (301) is provided in the application device (ground station side) A (101-102), and a destination selection control unit is not required in the application device (mobile station side) A (109). The rest of the configuration is the same as in Fig. 3.

[0051] In the configuration of Figure 5, when train 1 (205) is present in section a, application device (ground station side) A-1 (101) controls train 1 (205), and when train 1 (205) is present in section b, application device (ground station side) A-2 (101) controls train 1 (205). To realize this relationship, application device (mobile station side) A of train 1 (205) constantly transmits data to both application device (ground station side) A-1 (101) and application device (ground station side) A-2 (102).

[0052] The reception selection control unit (301) of the application device (ground station side) A (101-102) uses the position information of train 1 (205) as management information for reception selection, and the application device (ground station side) A-1 (101) adopts the received data and performs application control when the position information obtained from train 1 (205) indicates that the train is located within section a. When the position information obtained from train 1 (205) indicates that the train is located within section b, the received data is discarded and application control is not performed. Similarly, the application device (ground station side) A-2 (102) adopts the received data and performs application control when the position information obtained from train 1 (205) indicates that the train is located within section b, and discards the received data and does not perform application control when the position information obtained from train 1 (205) indicates that the train is located within section a.

[0053] The position information may be included in the data received from train 1 (205), or may be detected by other means such as a track circuit.

[0054] Next, referring again to Figure 4, we will explain how the application device (ground station side) B (103-104) determines whether reception is necessary by referring to the unique number (ID information) of the mobile station side device. For example, if the unique number (ID information) of the device obtained from the application device (mobile station side) B (110) is 4, the application device (ground station side) B-1 (103) uses the received data and performs application control. The application device (ground station side) B-2 (104) discards the data and does not perform control.

[0055] Although not shown in FIG. 4, the same applies when determining based on time / time information, and the reception selection control unit determines whether to adopt or discard the information obtained from application device (mobile station side) B (110) based on the time / time information registered in the database within the reception selection control unit.

[0056] (Effects of Example 2) In this way, application device (ground station side) A determines whether reception is necessary depending on the train location, so that processing can be distributed on the ground station side depending on the location of the mobile station side device while maintaining one VPN connection. Moreover, in the second embodiment, the reception selection control is performed on the terrestrial station side, and the mobile station side does not need to perform the destination selection control, so that it is possible to reduce the processing load on the mobile station side device and to simplify the configuration of the mobile station side device.

[0057] Although FIGS. 4 and 5 show an example in which the application device (ground station side) distributes processing to two devices, the reception selection method is the same when the processing is distributed to three or more devices.

[0058] As described above, the reception selection control unit (301) of the application device (ground station side) can determine whether reception is necessary. Conversely, when transmitting data from the application device (ground station side) (101-104) to the application device (mobile station side) (109-110), the data can be sent back to the application device (mobile station side) (109-110) that has determined that reception is necessary based on the reception necessity test, or a reception selection control unit may be provided in the application device (mobile station side) (109-110) to make the same determination. [Example]

[0059] Next, a wireless communication system and a wireless communication method according to a third embodiment will be described with reference to FIG. 6 is a diagram showing an example of a case where the configuration of a wireless communication system according to a third embodiment of the present invention is applied to a railway system. The third embodiment differs from the first and second embodiments in that the third embodiment includes multiple ground station VPN management devices, namely, VPN management device 1 (501) as a first VPN management device and VPN management device 2 (502) as a second VPN management device, and multiple VPNs are simultaneously established between the ground station side and the mobile station side. In the following description, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and their description will be simplified or omitted.

[0060] In the third embodiment, each application device does not need to manage and maintain a VPN connection, as in the first and second embodiments. On the other hand, by distributing the ground station VPN management devices (501, 502) according to the control section, even if a failure occurs in one of the ground station VPN management devices (501, 502), it is possible to suppress the impact of the failure, such as by keeping the communication downtime to zero.

[0061] The VPN connection between the mobile station side VPN control device (108) and the ground station side VPN control devices (501, 502) may be either a method of constantly maintaining both VPN connection 1 and VPN connection 2, or a method of initially establishing only VPN connection 1 and then adding VPN connection 2 as the mobile station approaches section b.

[0062] 6 shows an example in which there are two ground station VPN management devices (501, 502) and two VPN connections, but the ground station VPN management devices may be distributed among three or more. Furthermore, even when there are three or more VPN management devices, it is possible to arbitrarily decide whether to maintain VPN connections with all ground station VPN management devices at all times or to establish VPN connections with specific ground station VPN management devices as needed.

[0063] (Effects of Example 3) In this way, by arranging multiple terrestrial station VPN management devices for one mobile station VPN management device, it is possible to increase the reliability of VPN connections even when a failure occurs, and to more reliably reduce communication downtime to zero. [Example]

[0064] Next, a wireless communication system and a wireless communication method according to a fourth embodiment will be described with reference to FIG. FIG. 7 is a diagram illustrating an example in which the configuration of a wireless communication system according to a fourth embodiment of the present invention is applied to a railway system. The fourth embodiment differs from the first to third embodiments in that it includes multiple ground station VPN management devices (501, 703) to divide the control coverage area of ​​the ground station VPN management device. In the following description, the same or equivalent components as those in the first to third embodiments are denoted by the same reference numerals, and their description will be simplified or omitted. The fourth embodiment is similar to the first to third embodiments in that the mobile station side can exchange data with a plurality of terrestrial station side application devices via the same terrestrial station side VPN management device within a certain section.

[0065] Although the first to third embodiments do not describe the range managed by the ground station VPN management device, when controlling a mobile station application that moves over a wide area, the ground station VPN management device needs to control communications with a large number of mobile stations. Therefore, in the fourth embodiment, a certain section spanning multiple control ranges is designated as the control coverage area of ​​a specific ground station VPN management device, thereby distributing processing for the ground station VPN management device as well. This makes it possible to limit the number of mobile station VPN management devices connected to the ground station VPN management device, and to keep the processing load of the ground station VPN management device within a certain range.

[0066] In Fig. 7, the mobile station VPN control device (108) establishes a VPN connection with the ground station VPN control device 1 (501) while the train 1 (205) is traveling in sections a and b, and then establishes a VPN connection with the ground station VPN control device 3 (703) while the train 1 (205) is traveling in section c. By covering sections a and b with the same ground station VPN management device 1 (501), it is possible to eliminate the need to switch VPN connections even when the application control range spans multiple areas and communication with the connected application device is switched, as shown in Examples 1 and 2.

[0067] On the other hand, when train 1 (205) enters section b from section c, the ground-side VPN control device that relays application data switches from ground station VPN control device 1 (501) to ground station VPN control device 3 (703). In such a case, an area where the coverage areas of ground station VPN control device 1 (501) and VPN control device 3 (703) overlap can be provided, and multiple VPN connections can be used temporarily in combination using the method shown in embodiment 3, so that communication interruptions due to VPN communication switching do not occur even when the application device selects and switches its destination.

[0068] (Effects of Example 4) In the fourth embodiment, it is possible to distribute the processing of the ground station side VPN management device, and when switching the ground side VPN management device, by using multiple ground side VPN management devices in combination, This will prevent VPN connection interruptions and make it possible to more consistently achieve zero communication downtime.

[0069] Although Examples 1 to 4 have been described above as embodiments of the present invention, the present invention is not limited to the above-described Examples 1 to 4, and various modifications are possible within the scope of the present invention. It goes without saying that the application device, VPN management measures, ground stations, mobile stations, trains, the number of sections, etc. described in this disclosure can be changed as appropriate. Furthermore, as for the information specific to the mobile station side device, appropriate information other than that shown in this disclosure can also be used. In addition, in this disclosure, application examples of the wireless communication system and wireless communication method have been described using a railway system, but the wireless communication system and wireless communication method of the present disclosure can be applied to various fields that use wireless communication other than railway systems.

[0070] Furthermore, the above-described configurations, functions, and processing units may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-described configurations and functions may also be implemented in software by a processor interpreting and executing a program that implements each function. In this case, information about the program that implements each function may be stored in a storage device such as a memory or a hard disk, or in a storage medium such as an IC card, SD card, or DVD.

[0071] The present disclosure includes the following aspects. (Aspect 1) A wireless communication system connecting a ground station side application device and a mobile station side application device, a ground station side VPN connection management device and a mobile station side VPN connection management device are provided between the ground station side application device and the mobile station side application device, VPN connection management is performed in the VPN connection management device on the ground station side and the VPN connection management device on the mobile station side, Even if a ground station side application device connected to the mobile station side application device is changed, the VPN connection between the ground station side VPN connection management device and the mobile station side VPN connection management device continues. A wireless communication system comprising:

[0072] (Aspect 2) In the wireless communication system according to aspect 1, The mobile station side device includes a destination control unit that selects and controls a destination terrestrial station side application device based on the unique information of the mobile station side device. A wireless communication system comprising:

[0073] (Aspect 3) In the wireless communication system according to aspect 2, the destination control unit is provided in the mobile station side application device, The information specific to the mobile station side device is at least one of a unique number (ID) of the mobile station side device, location information of the mobile station, and time information. A wireless communication system comprising:

[0074] (Aspect 4) In the wireless communication system according to aspect 1, The ground station side device has a reception selection control unit that selects and controls a destination ground station side application device based on the unique information of the mobile station side device. A wireless communication system comprising:

[0075] (Aspect 5) In the wireless communication system according to aspect 4, the reception selection control unit is provided in the ground station side application device, The information specific to the mobile station side device is at least one of a unique number (ID) of the mobile station side device, location information of the mobile station, and time information. A wireless communication system comprising:

[0076] (Aspect 6) In the wireless communication system according to any one of aspects 1 to 5, There are multiple VPN management devices on the ground station side. The mobile station VPN connection management device can simultaneously establish a VPN connection with the first ground station VPN management device and the second ground station VPN management device. A wireless communication system comprising:

[0077] (Aspect 7) In the wireless communication system according to any one of aspects 1 to 3 or 6, The ground station side VPN management device is provided in plurality to divide the control coverage area, When the mobile station moves from the control coverage area of ​​a first ground station VPN management device to the control coverage area of ​​a second ground station VPN management device, the mobile station VPN management device can establish a VPN connection with both the first ground station VPN management device and the second ground station VPN management device. A wireless communication system comprising:

[0078] (Aspect 8) In a wireless communication method using the wireless communication system according to aspect 1, Establishing a VPN connection between the ground station side VPN connection management device and the mobile station side VPN connection management device, a destination selection control unit of the mobile station side application device selects a destination of data from among the terrestrial station side application devices based on information specific to the mobile station side device; Using the VPN connection between the mobile station VPN management device and the ground VPN connection management device, data is sent to the desired ground station application device. A wireless communication method comprising:

[0079] (Aspect 9) In the wireless communication method according to aspect 8, The information specific to the mobile station side device is at least one of a unique number (ID) of the mobile station side device, location information of the mobile station, and time information. A wireless communication method comprising:

[0080] (Aspect 10) In the wireless communication method according to aspect 8 or 9, Instead of the destination selection control unit of the mobile station side application device, the ground station side application device is provided with a reception selection control unit that selects and controls a destination ground station side application device based on the unique information of the mobile station side device, the mobile station side application device transmits data to all terrestrial station side application devices without specifying a terrestrial station side application device as a transmission destination; The ground station side application device receives data, and in a reception selection control unit, If it is determined that the data is from a mobile station side application device that should be controlled by the own device, the application control is performed; If it is determined that the data is from a mobile station side application device that should not be controlled by the own device, the data is discarded. A wireless communication method comprising:

[0081] (Aspect 11) 11. The wireless communication method according to any one of aspects 8 to 10, There are multiple VPN management devices on the ground station side. The mobile station VPN connection management device simultaneously establishes a VPN connection with the first ground station VPN management device and the second ground station VPN management device. A wireless communication method comprising:

[0082] (Aspect 12) 12. The wireless communication method according to any one of aspects 8 to 11, There are multiple VPN management devices on the ground station side, each with its own control coverage area. While the mobile station is moving through a coverage area controlled only by the first ground station side VPN control device, the mobile station establishes a VPN connection with the first ground station side VPN control device; while the mobile station is moving through an area where the control coverage area of ​​a first ground station VPN management device and the control coverage area of ​​a second ground station VPN management device overlap, the mobile station VPN management device establishes a VPN connection with both the first ground station VPN management device and the second ground station VPN management device; While the mobile station is moving through a control coverage area of ​​only the second ground station side VPN management device, the mobile station establishes a VPN connection with the second ground station side VPN management device. A wireless communication system comprising: [Explanation of symbols]

[0083] 101: Application device (ground station side) A-1 102: Application device (ground station side) A-2 103: Application device (ground station side) B-1 104: Application device (ground station side) B-2 105: Ground station side VPN management device 107: Mobile station 108: Mobile station side VPN management device 109: Application device (mobile station side) A 110: Application device (mobile station side) B 111: Destination selection control unit 202: Ground Station 1 203: Ground Station 2 204: Ground Station 3 205:Train 1 301: Reception selection control unit 401: Communication Network 1 402: Communication Network 2 501: Ground station side VPN management device 1 502: Ground station side VPN management device 2 701: Application device (ground station side) A-3 703: Ground station side VPN management device 3

Claims

1. A wireless communication system connecting a ground station side application device and a mobile station side application device, a ground station side VPN connection management device and a mobile station side VPN connection management device are provided between the ground station side application device and the mobile station side application device, performing VPN connection management in the VPN connection management device on the ground station side and the VPN connection management device on the mobile station side; Even if a ground station side application device connected to the mobile station side application device is changed, the VPN connection between the ground station side VPN connection management device and the mobile station side VPN connection management device continues. A wireless communication system comprising:

2. 2. The wireless communication system according to claim 1, The mobile station side device includes a destination control unit that selects and controls a destination terrestrial station side application device based on the unique information of the mobile station side device. A wireless communication system comprising:

3. 3. The wireless communication system according to claim 2, the destination control unit is provided in the mobile station side application device, The information specific to the mobile station side device is at least one of a unique number (ID) of the mobile station side device, location information of the mobile station, and time information. A wireless communication system comprising:

4. 2. The wireless communication system according to claim 1, The ground station side device includes a reception selection control unit that selects and controls a destination ground station side application device based on the unique information of the mobile station side device. A wireless communication system comprising:

5. 5. The wireless communication system according to claim 4, the reception selection control unit is provided in the ground station side application device, The information specific to the mobile station side device is at least one of a unique number (ID) of the mobile station side device, location information of the mobile station, and time information. A wireless communication system comprising:

6. 6. The wireless communication system according to claim 1, There are multiple VPN management devices on the ground station side, The mobile station VPN connection management device is capable of simultaneously establishing a VPN connection with the first ground station VPN management device and the second ground station VPN management device. A wireless communication system comprising:

7. 7. The wireless communication system according to claim 6, The ground station-side VPN management device is provided in plurality to divide the control coverage area, When the mobile station moves from a control coverage area of ​​a first ground station VPN management device to a control coverage area of ​​a second ground station VPN management device, the mobile station VPN management device can establish a VPN connection with both the first ground station VPN management device and the second ground station VPN management device. A wireless communication system comprising:

8. 2. A wireless communication method using the wireless communication system according to claim 1, Establishing a VPN connection between the ground station VPN connection management device and the mobile station VPN connection management device; a destination selection control unit of the mobile station side application device selects a destination of data from among the terrestrial station side application devices based on information specific to the mobile station side device; Using a VPN connection between the mobile station VPN management device and the ground VPN connection management device, data is sent to a desired ground station application device. A wireless communication method comprising:

9. 9. The wireless communication method according to claim 8, The information specific to the mobile station side device is at least one of a unique number (ID) of the mobile station side device, location information of the mobile station, and time information. A wireless communication method comprising:

10. 9. The wireless communication method according to claim 8, Instead of the destination selection control unit of the mobile station side application device, the ground station side application device is provided with a reception selection control unit that selects and controls a destination ground station side application device based on the unique information of the mobile station side device, the mobile station side application device transmits data to all terrestrial station side application devices without specifying a terrestrial station side application device as a transmission destination; The ground station side application device receives data, and in a reception selection control unit, If it is determined that the data is from a mobile station side application device that should be controlled by the own device, the application control is performed; If it is determined that the data is from a mobile station side application device that should not be controlled by the own device, the data is discarded. A wireless communication method comprising:

11. 9. The wireless communication method according to claim 8, There are multiple VPN management devices on the ground station side, The mobile station VPN connection management device establishes a VPN connection with the first ground station VPN management device and the second ground station VPN management device simultaneously. A wireless communication method comprising:

12. 9. The wireless communication method according to claim 8, The VPN management device on the ground station side is provided in multiple locations, dividing the control coverage area. While the mobile station is moving in a coverage area controlled only by the first ground station VPN management device, the mobile station establishes a VPN connection with the first ground station VPN management device; while the mobile station is moving through an area where a control coverage area of ​​a first ground station side VPN management device and a control coverage area of ​​a second ground station side VPN management device overlap, the mobile station side VPN management device establishes a VPN connection with both the first ground station side VPN management device and the second ground station side VPN management device; While the mobile station is moving through a control coverage area covered only by the second ground station VPN management device, the mobile station establishes a VPN connection with the second ground station VPN management device. A wireless communication system comprising:

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