WIRELESS SYSTEM AND GROUND-TO-VEHICLE TRANSMISSION METHOD

Abstract

Wireless system (1, 1A), comprising: a wireless device (200) installed on the ground along a track; and a plurality of wireless devices (100, 120, 140, 160) installed in a train (500) in a row from one end to one rear of the train (500), wherein If the ground-installed wireless device (200) and the multiple wireless devices (100, 120, 140, 160) installed in the train (500) communicate using a proximity service, a restriction is imposed such that only one of the multiple wireless devices (100, 120, 140, 160) is connected to the ground-installed wireless device (200). from the multitude of wireless devices (100, 120, 140, 160) installed in the train (500), the wireless device (120, 140, 160) not installed at the front in the direction of travel of the train (500) upon detection of the wireless device (200) installed on the ground submits a request for permission to connect with the wireless device (200) installed on the ground to the wireless device (100) installed at the front in the direction of travel of the train (500) among the multitude of wireless devices (100, 120, 140, 160), Upon receiving the request for communication permission with the wireless device (200) installed on the ground from the wireless device (120, 140, 160) not installed at the head, the wireless device (100) installed at the head in the direction of travel of the train (500) grants the communication permission to the wireless device installed at a position closest to the head in the direction of travel of the train (500) under one or more wireless devices (120, 140, 160) that made the request, and Of the many wireless devices (100, 120, 140, 160) installed in the train (500), the wireless device that has received permission to connect communicates with the wireless device (200) installed on the ground.

Description

AREA

[0001] The present disclosure relates to a wireless system comprising a ground-installed wireless device and a train-installed wireless device, and to a ground vehicle or land vehicle transmission method that is a communication method for the wireless system. BACKGROUND

[0002] To ensure the safe operation of trains, methods for monitoring people and obstacles on the tracks from the ground, while the train is in motion, have become a focus. Examples of areas on the ground include near platforms, level crossings, and construction sites. One example of a method for monitoring people and obstacles on the tracks is the transmission of video from the ground to a train using Proximity Service (ProSe) in Device-to-Device (D2D) communication, and the display of the transmitted video, for example, on a video screen installed in the cabin. This method also makes it possible to transmit vehicle log data from the train to a ground station, installed, for example, at the entrance to a station area, while the train is in motion. The station area includes a return path.

[0003] Patent literature 1 discloses a technique for performing resource acquisition during D2D communication in a vehicle-internal communication system. The vehicle-internal communication is V2X (Vehicle-to-Everything) communication.Patent literature 2 discloses a wireless relay device comprising a receiving unit for receiving train control information; an information classification unit for classifying the train control information into first control information, which requires immediate transmission, and second control information, which does not require immediate transmission; a message generation unit for generating a message from the first control information contained in one train control information and for generating a message from several second control information contained in several train control informations; and a transmission unit for transmitting the messages generated by the message generation unit. Patent literature 3 discloses a technology in which the number of cell end tapes is limited.The upper limit of the number of cell end bands in each cell is then set such that the number of cell end bands is limited based on this upper limit. The number of cell end connections is also limited. Furthermore, the upper limit of the number of cell end connections is set to limit the number of cell end connections based on this upper limit. Patent literature 4 discloses a method for operating a base station in a communication system between trains, comprising the following steps: receiving a neighbor search request message from a first train terminal to search for another neighboring train terminal; sending a reply message with information about a train terminal located in the base station to the first train terminal in response to the received neighbor search request message; and sending the received neighbor search request message to another base station.Patent literature 5 discloses a method for selecting the communication mode and allocating resources in train-to-train communication in rail transport, which takes into account a joint selection of the communication mode and resource allocation under the condition that a T2G communication mode and a T2T communication mode exist side by side, so that a train can adaptively select a communication mode with better communication quality. REFERENCE LIST PATENT LITERATURE Patent literature 1: JP 6669041 B2 Patent literature 2: WO 2020 / 148 893 A1 Patent literature 3: JP 2010 - 283 632 A Patent literature 4: KR 10 2019 0 043 009 A Patent Literature 5: CN 112 788 563 A SUMMARY OF THE TECHNICAL PROBLEM

[0004] To transmit video from the ground to the vehicle and continue monitoring until the rear of the train passes the monitoring area, several wireless devices can be positioned on the vehicle. These devices can receive the video from the ground and then transmit it to the wireless device connected to the video screen. However, this leads to an overload of the wireless bandwidth available to the multiple wireless devices on the vehicle.

[0005] Patent literature 1 discloses a method for allocating D2D communication resources, but not a method for reducing wireless bandwidth overload. Therefore, it is necessary to reduce wireless bandwidth overload in multiple wireless devices within the vehicle during ProSe-based ground-to-vehicle communication.

[0006] The present disclosure was made in consideration of the above statements, and its aim is to achieve a wireless system that enables the operator of a train to efficiently carry out the work of monitoring obstacles on the track, reducing the overload of the wireless bandwidth or radio bandwidth in a multitude of wireless devices on or in the vehicle. SOLUTION TO THE TASK

[0007] To solve the problem and achieve the goal described above, a wireless system according to the present disclosure comprises: a wireless device installed on the ground along a track; and a plurality of wireless devices installed in a train in a line from one end to the rear of the train. When the wireless device installed on the ground and the plurality of wireless devices installed in the train communicate via the proximity service, a restriction is imposed such that only one of the plurality of wireless devices is connected to the wireless device installed on the ground. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0008] The wireless system according to the present disclosure can achieve the effect that the operator of a train can efficiently perform the work of monitoring obstacles on the track, while reducing the overload of the wireless bandwidth in a variety of wireless devices on the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a representation showing a configuration of a train-to-train or train-to-infrastructure (T2X) system according to a first embodiment. Fig. Figure 2 is a representation showing a hardware configuration of a wireless device in the T2X system according to the first embodiment. Fig. Figure 3 is a representation showing a hardware configuration of another form of the wireless device included in the T2X system according to the first embodiment. Fig. Figure 4 is a representation showing a functional configuration of the wireless device in the T2X system according to the first embodiment. Fig. Figure 5 is a sequence diagram illustrating a method for the operation of ground-vehicle communication in the T2X system according to the first embodiment. Fig. Figure 6 is a representation illustrating the planning of wireless communication according to the first embodiment. Fig. Figure 7 is a representation showing a configuration of a T2X system according to a second embodiment. Fig. Figure 8 is a sequence diagram showing a method for the operation of ground-vehicle communication in the T2X system according to the second embodiment. Fig. Figure 9 is a representation showing a configuration of a T2X system according to a third embodiment. Fig. Figure 10 is a representation showing a configuration of a T2X system according to a fourth embodiment. DESCRIPTION OF THE EXAMPLES OF EXECUTION

[0009] A wireless system and a ground-to-vehicle transmission method according to the exemplary embodiments are described in detail below with reference to the drawings. First embodiment.

[0010] Fig. Figure 1 is a diagram showing a configuration of a T2X system 1 according to a first embodiment. The T2X system 1 is a wireless system comprising a wireless device 200 installed on the ground along a track and a plurality of wireless devices 100, 120, 140, and 160 installed on a train assembly 500. The plurality of wireless devices 100, 120, 140, and 160 are installed in a line from the front to the rear of the train assembly 500.

[0011] This ground-mounted wireless device 200 transmits the data to the train assembly 500. An application example for the T2X system 1 could be a track monitoring system that transmits the video from a ground-mounted surveillance camera to a vehicle and displays the video on a video screen inside the vehicle. If the ground-mounted wireless device 200 and the multiple wireless devices 100, 120, 140, and 160 installed on the train assembly 500 communicate using the proximity service, the T2X system 1 restricts communication so that only one of the multiple wireless devices 100, 120, 140, and 160 is connected to the ground-mounted wireless device 200 at any given time.

[0012] A vehicle-integrated superior device 300 is connected to the wireless device 100. The vehicle-integrated superior device 300 is contained within the train assembly 500. The wireless devices 100, 120, 140, and 160 are arranged on the train assembly 500 in a line from front to rear in the direction of travel of the train assembly 500, in that order. The wireless devices 100, 120, 140, and 160 each communicate with an adjacent wireless device via ProSe Unicast. That is, ProSe Unicast communication takes place between the wireless device 100 and the wireless device 120, between the wireless device 120 and the wireless device 140, and between the wireless device 140 and the wireless device 160.

[0013] The train arrangement 500 travels in the direction from wireless device 160 to wireless device 100, i.e. in Fig. 1 in the right direction. A superior ground device 400 is connected to the wireless device 200. The wireless device 200 communicates with the wireless devices 100, 120, 140 and 160, which are located on the train arrangement 500, via ProSe Layer 2 Groupcast. Although Fig. Figure 1 shows that the four wireless devices 100, 120, 140 and 160 are installed on or attached to the train assembly 500; therefore, the number of wireless devices arranged on the train assembly 500 must be only two or more. Although Fig. Figure 1 shows that wireless device 200 communicates with wireless device 100 and wireless device 120; wireless device 200 can communicate with all wireless devices located on train arrangement 500 within its communication range.

[0014] Fig. Figure 2 is a diagram showing a hardware configuration of the wireless device 100 included in the T2X system 1 according to the first embodiment. The wireless device 100 comprises a wireless interface termination unit 101, a memory 102, a central processing unit (CPU) 103, a wired interface termination unit 104, and a power supply circuit 105. The memory 102 is, for example, a semiconductor memory.

[0015] Fig. Figure 3 is a representation showing a hardware configuration of another form of the wireless device 100 included in the T2X system 1 according to the first embodiment. The wireless device 100 in Fig. 3 differs from the wireless device 100 in Fig. 2 by the fact that the memory 102 and the CPU 103, which are in the wireless device 100 in Fig. 2 are included, through processing circuits 106 in the wireless device 100 in Fig. 3 can be replaced. The configuration of the wireless device 100 can either be the configuration in Fig. 2 or the configuration in Fig. 3 be.

[0016] Fig. Figure 4 is a diagram showing a functional configuration of the wireless device 100 in the T2X system 1 according to the first embodiment. The wireless device 100 includes a wired transmit / receive unit 111, which performs a wired communication data transmit / receive operation, and a wireless transmit / receive unit 112, which performs a wireless communication data transmit / receive operation and schedules a wireless communication time. The wireless device 100 further includes a control unit 113, which sets a ProSe Layer 2 group identifier (ID), processes transmit / receive messages, and references information stored in memory, and a connection permission response determination unit 114, which performs the response and determines the connection permission with the ground-installed wireless device 200.

[0017] The wireless device 100 further comprises a switching time determination unit 115, which determines a function shift time with respect to the response and the determination of the connection permission, and a storage unit 116, which contains the ProSe Layer-2 group ID of the wireless device 100, information about the wireless device that made a request for connection permission, information indicating whether the wireless device 100 is the leading wireless device, information indicating the distance between the wireless devices in the train arrangement 500, and information indicating the specified travel speed at the installation location of the wireless device 200 on the ground.

[0018] The functions of the wired transceiver unit 111, the wireless transceiver unit 112, the control unit 113, the link permission response determination unit 114, and the switching time determination unit 115 can be implemented by a CPU executing a program, or they can be implemented by an associated circuit. In a case where a CPU implements the above-mentioned functions, the wireless device 100 comprises the one described in Fig. The memory 102 and the CPU 103 are shown in Figure 2. Information for implementing the functions of the wired transceiver 111, the wireless transceiver 112, the control unit 113, the connection permission response determination unit 114, and the switching time determination unit 115 is described as a program and stored in memory 102. The CPU 103 reads the program stored in memory 102 and executes it to implement the functions of the wired transceiver 111, the wireless transceiver 112, the control unit 113, the connection permission response determination unit 114, and the switching time determination unit 115.

[0019] In a case where a dedicated circuit implements the functions described above, the wireless device 100 contains the components described above. Fig. The 3 processing circuits 106 shown, and the processing circuits 106 implement the functions of the wired transceiver 111, the wireless transceiver 112, the control unit 113, the link permission response determination unit 114, and the switching time determination unit 115. Some of the functions of the wired transceiver 111, the wireless transceiver 112, the control unit 113, the link permission response determination unit 114, and the switching time determination unit 115 can be implemented by a dedicated circuit, and the remaining functions can be implemented by a program and a CPU.

[0020] The configuration of Wireless Device 120, Wireless Device 140, Wireless Device 160 and Wireless Device 200 is the same as the configuration of Wireless Device 100.

[0021] Fig. Figure 5 is a sequence diagram illustrating a procedure for operating ground-vehicle communication in the T2X system 1 according to the first embodiment. Fig. Figure 6 illustrates the scheduling of wireless communication according to the first embodiment. In the T2X system 1, the ground-installed wireless device 200 and the multiple wireless devices 100, 120, 140, and 160 installed on the train assembly 500 perform data communication and connection permission requests at different times using the Proximity Service scheduling. That is, in the T2X system 1, ground-vehicle data communication, connection permission requests and responses, and vehicle-to-vehicle data communication are performed at different times using the ProSe scheduling, thereby reducing message and data congestion.

[0022] The in Fig. The flowchart shown in Figure 6 indicates that ground-vehicle data communication, the connection permission request and response, and vehicle-to-vehicle data communication are planned in this order. However, ground-vehicle data communication, the connection permission request and response, and vehicle-to-vehicle data communication can be implemented in a different order than shown. Fig. The sequence shown in section 6 will be followed. Each communication point can be any communication point.

[0023] Next, the functionality of the T2X system 1 will be explained with reference to Fig. 5 described, in which ground-vehicle communication is carried out, whereby only one vehicle-owned wireless device can carry out the ground-vehicle communication in order to avoid overloading the wireless bandwidth between the vehicle-owned wireless devices.

[0024] Wireless Device 100, Wireless Device 120, Wireless Device 140, and Wireless Device 160 configure the same ProSe Layer-2 group ID at Control Unit 113, which is stored in Memory Unit 116 (S1). The wireless transmit / receive units 112 of adjacent wireless devices perform a data transmission / receive procedure to establish a unicast connection (S2). Adjacent wireless devices are Wireless Device 100 and Wireless Device 120, Wireless Device 120 and Wireless Device 140, and Wireless Device 140 and Wireless Device 160.

[0025] Wireless Device 200 sets a ProSe Layer-2 group ID in Control Unit 113 that corresponds to the ID of the onboard wireless devices located in Storage Unit 116 (S3). The superior ground device 400 transmits data to Wireless Device 200, and Wireless Device 200 receives the data transmitted by the superior ground device 400 at Wired Transceiver Unit 111 (S4). Wireless Device 200 performs a data transmission operation at Wireless Transceiver Unit 112 to transmit the data via groupcast (S5).

[0026] As the train assembly 500 approaches the installation location of the wireless device 200, the wireless device 100 receives the data transmitted by the wireless device 200 at the wireless transceiver unit 112 and forwards it via the wired transceiver unit 111 to the vehicle's onboard superior device 300 (S6). After receiving the data at the wireless transceiver unit 112, the wireless device 120 at the control unit 113 refers to the information stored in the memory unit 116 and indicates whether the wireless device 120 is a head-mounted wireless device. After confirmation that the wireless device 120 is a non-head-mounted wireless device, it sends a connection permission request message to the wireless device 100 via the wireless transceiver unit 112 (S7).

[0027] Wireless device 100 receives the connection permission request message at wireless transmit / receive unit 112, and the control unit 113 in wireless device 100 requests the connection permission response determination unit 114 to determine the connection permission. The connection permission response determination unit 114 refers to the information stored in the memory unit 116 about the wireless device that made the connection permission request and determines whether the connection should be allowed (S8). Since wireless device 100 received the connection permission request from wireless device 120, the connection permission response determination unit 114 of wireless device 100 determines in step S8 that the connection is not allowed.

[0028] In wireless device 100, the connection permission response unit 114 generates a notification that the connection is not permitted, the control unit 113 forwards the notification that the connection is not permitted to the wireless transmit / receive unit 112, and the wireless transmit / receive unit 112 notifies the wireless device 120 that the connection is not permitted (S9).

[0029] After the operation in step S9 has been carried out, wireless device 200 sends data to train assembly 500 (S10). As soon as wireless device 100 can no longer receive data from wireless device 200 due to the movement of train assembly 500, wireless device 120, which has received the data transmitted by wireless device 200, sends a request for permission to connect to wireless device 100 (S11).The wireless device 100, which received the connection permission request, refers to the data held in the storage unit 116 at the connection permission response determination unit 114, confirms that the wireless device 100 has not received any data from the wireless device 200 and that the wireless device 120 is a wireless device installed at the position closest to the head among the wireless devices that made the connection permission request, and determines to allow the connection (S12).

[0030] In wireless device 100, the connection permission response unit 114 generates a notification that the connection is permitted. The control unit 113 forwards the notification that the connection is permitted to the wireless transceiver unit 112, and the wireless transceiver unit 112 notifies wireless device 120 that the connection is permitted (S13). Upon receiving the notification of connection permission at wireless transceiver unit 112, wireless device 120 transmits the data received from wireless device 200 by unicast via wireless transceiver unit 112 to wireless device 100 (S14). Wireless device 100 transmits the data via wired transceiver unit 111 to the vehicle's own higher-level device 300 (S15).

[0031] The function performed by wireless device 100 at the connection permission response determination unit 114 switches to the next wireless device 120 according to the movement of the train assembly 500 (S16). This function determines the connection permission and responds to it. The function switches to the next wireless device each time the time calculated from the travel speed of the train assembly 500, its acceleration, and the distance between wireless device 100 and wireless device 120, or the time calculated from the predetermined travel speed at the installation location of wireless device 200 on the ground and the distance between wireless device 100 and wireless device 120, elapses.

[0032] It should be noted that the timing calculation is performed by the switching time determination unit 115. The switching time determination unit 115 refers to the information stored in the storage unit 116 regarding the distance between the wireless device 100 and the wireless device 120 and the specified travel speed at the installation location of the wireless device 200. Information specifying the travel speed and acceleration of the train assembly 500 is obtained by the switching time determination unit 115. The starting point of the switching time is the time at which the wireless device 100 first receives data. Information specifying the time of the starting point is transmitted by the wireless transceiver unit 112 to the wireless device 120 at the time of the response to the request for permission to connect.

[0033] After the function of responding and determining the connection permission was switched from wireless device 100 to wireless device 120 in step S16, wireless device 120 can receive data from wireless device 200 (S17). Wireless device 120 does not request connection permission and transmits the data to wireless device 100 via unicast through wireless transceiver 112 (S18). Wireless device 100 then transmits the data to the vehicle's onboard master device 300 via wired transceiver 111 (S19).

[0034] After receiving the data transmitted by wireless device 200 to wireless transceiver 112, wireless device 140 submits a connection permission request to wireless device 120 using an operation similar to the operation in step S7 (S20). Wireless device 120 determines whether a connection is permitted and notifies wireless device 140 of its refusal using operations similar to those in steps S8 and S9 (S21, S22).

[0035] The train assembly 500 continues to move after the operation of step S22 has been performed, and then operations similar to those described above are carried out. For example, if wireless device 140 has the function of responding and determining the connection permission, and wireless device 160 receives the transmission data from wireless device 200 (S23), wireless device 160 makes a connection permission request to wireless device 140 using an operation similar to the operation in step S11 (S24), and wireless device 140 determines the connection permission and notifies wireless device 160 of the connection permission using operations similar to the operations in steps S12 and S13 (S25, S26).

[0036] Wireless device 160 transmits the data received by wireless device 200 at wireless transceiver unit 112 via unicast to wireless device 140. Wireless device 140 transmits the data via unicast to wireless device 120. Wireless device 120 transmits the data via unicast to wireless device 100 (S27). Wireless device 100 transmits the data via wired transceiver unit 111 to the vehicle's own higher-level device 300 (S28).

[0037] If, as described above, the ground-installed wireless device 200 and the plurality of wireless devices 100, 120, 140, and 160 installed on the train assembly 500 communicate using a proximity service, the T2X system 1, according to the first embodiment, imposes a restriction so that only one of the plurality of wireless devices 100, 120, 140, and 160 is connected to the ground-installed wireless device 200. As a result, the T2X system 1 can cause the plurality of wireless devices 100, 120, 140, and 160 installed on the train assembly 500 to transmit data while reducing wireless bandwidth congestion. Consequently, the T2X system 1 can enable the train assembly 500 operator to efficiently monitor for obstacles along the track.

[0038] As described above, the T2X system 1 initially restricts communication between the multiple wireless devices 100, 120, 140, and 160 installed on the train assembly 500, and the wireless device 100, which is installed at the front of the train assembly 500 in the direction of travel. This reduces the overload of the wireless bandwidth among the multiple wireless devices 100, 120, 140, and 160.

[0039] As described above, in the T2X system 1, among the multitude of wireless devices 100, 120, 140 and 160 installed on the train arrangement 500, the wireless devices 120, 140 and 160 that are not installed at the head in the direction of travel of the train arrangement 500, upon detecting the wireless device 200 installed on the ground, submit a request for permission to connect with the wireless device 100 installed at the head in the direction of travel of the train arrangement 500.Upon receiving a connection request from a wireless device not installed at the front of the train, the wireless device 100, installed at the front of the train assembly 500 in the direction of travel, grants connection permission to the wireless device located closest to the front of the train assembly 500 in the direction of travel, among one or more wireless devices that made the request. Of the multiple wireless devices 120, 140, and 160 installed on the train assembly 500, the wireless device that received the connection permission communicates with the wireless device 200 installed at the front. This reduces the wireless bandwidth congestion among the multiple wireless devices 100, 120, 140, and 160.

[0040] In T2X system 1, the function in which a wireless device of the plurality of wireless devices 100, 120, 140 and 160 installed in the train arrangement 500 receives a request for permission to connect with the ground-installed wireless device 200 from another wireless device other than the one wireless device of the plurality of wireless devices 100, 120, 140 and 160, and then the one wireless device grants permission to connect to the wireless device installed at a position closest to the head in the direction of travel of the train arrangement 500, among one or more wireless devices that made the request, and switches to subsequent wireless devices in sequence from the wireless device installed at the head in the direction of travel of the train arrangement 500, among the plurality of wireless devices 100, 120, 140 and 160,which are installed on the train assembly 500, at the following time in accordance with the movement of the train assembly 500. The time specification is a time specification calculated from the speed of the train assembly 500, the acceleration of the train assembly 500 and the distance between adjacent wireless devices of the plurality of wireless devices 100, 120, 140 and 160 installed on the train assembly 500, or a time specification calculated from the specified travel speed at the installation location of the wireless device 200, which is installed on the ground, and the installation position of the plurality of wireless devices 100, 120, 140 and 160 installed on the train assembly 500.

[0041] In T2X system 1, a first wireless device (100, 120, 140, and 160) from among the multiple wireless devices installed on train configuration 500 notifies a second wireless device (100, 120, 140, and 160) of information required to establish a connection and perform security authentication with the ground-based wireless device 200. This eliminates at least part of the connection establishment and security authentication process by the second wireless device.In accordance with the movement of the train arrangement 500, at a time calculated from the speed of the train arrangement 500, the acceleration of the train arrangement 500 and the distance between adjacent wireless devices of the plurality of wireless devices 100, 120, 140 and 160 installed on the train arrangement 500, or at a time calculated from the specified travel speed at the installation location of the ground-installed wireless device 200 and the installation position of the plurality of wireless devices 100, 120, 140 and 160 installed on the train arrangement 500, the wireless device communicating with the ground-installed wireless device 200 is switched among the plurality of wireless devices 100, 120, 140 and 160 installed on the train arrangement 500. Second embodiment.

[0042] In the first embodiment, data is transmitted between the wireless device 200 on the ground and the wireless devices 100, 120, 140, and 160 installed on the train assembly 500 via ProSe Groupcast. In the second embodiment, data is transmitted via ProSe Unicast between the wireless device 200 on the ground and the wireless devices 100, 120, 140, and 160 installed on the train assembly 500. The second embodiment mainly describes the differences from the first embodiment.

[0043] Fig. Figure 7 is a diagram showing a configuration of a T2X system 1A according to the second embodiment. Wireless device 100, wireless device 120, wireless device 140, and wireless device 160 have the same ProSe User Equipment (UE) ID and belong to the same ProSe Layer 2 group. As described above, wireless device 200 communicates with wireless device 100, wireless device 120, wireless device 140, and wireless device 160, which are installed on train assembly 500, via ProSe Unicast.

[0044] Although Fig. Figure 7 shows that the four wireless devices 100, 120, 140 and 160 are installed on the train arrangement 500; therefore, the number of wireless devices arranged on the train arrangement 500 must be only two or more. Although Fig. Figure 7 shows that wireless device 200 communicates with wireless device 120; wireless device 200 can communicate with all wireless devices located on train arrangement 500 within its communication range.

[0045] Fig. Figure 8 is a sequence diagram illustrating a method for the operation of ground-vehicle communication in the T2X system 1A according to the second embodiment. In the second embodiment, the data is transmitted via unicast, as described above. The operation of the T2X system 1 is described with reference to Fig. 8 described, in which ground-vehicle communication is carried out, whereby only one vehicle-owned wireless device can carry out the ground-vehicle communication in order to avoid overloading the wireless bandwidth between the vehicle-owned wireless devices.

[0046] Wireless Device 100, Wireless Device 120, Wireless Device 140, and Wireless Device 160, installed on Train Arrangement 500, configure the same ProSe UE ID and ProSe Layer-2 Group ID at Control Unit 113, which are stored in Memory Unit 116 (S31). As Train Arrangement 500 approaches the location where Wireless Device 200 is installed, Wireless Device 100 and Wireless Device 200 send and receive a message to establish a ProSe unicast connection via Wireless Transmit / Receive Unit 112 and establish the unicast connection (S32).

[0047] The wireless device 200 receives data from the higher-level ground device 400 at the wired transceiver unit 111 (S33) and transmits the data via the wireless transceiver unit 112 to the wireless device 100. The wireless device 100 receives the data from the wireless device 200 at the wireless transceiver unit 112 (S34). The wireless device 100 transmits the received data via the wired transceiver unit 111 (S35) to the vehicle's own higher-level device 300.

[0048] After establishing the unicast connection with wireless device 200, wireless device 100 stores the information required for connection establishment and security authentication in storage unit 116 and transmits the information via ProSe groupcast through wireless transmit / receive unit 112 (S36) to wireless device 120, wireless device 140, and wireless device 160. The information required for connection establishment and security authentication includes the ProSe UE ID, the ProSe Layer 2 group ID, the application layer ID, and the security information.

[0049] At this point, the wireless devices installed in train configuration 500, other than the rearmost wireless device 160 (i.e., wireless device 120 and wireless device 140), forward the connection establishment information received from the wireless device at the front of the train via ProSe groupcast. This allows all wireless devices 100, 120, 140, and 160 in train configuration 500 to receive the information required for connection establishment and security authentication. Wireless devices 120, 140, and 160 then themselves input the connection establishment and security authentication information they received at the wireless transceiver unit 112 into the control unit 113 and store the information in the storage unit 116 (S37).

[0050] In accordance with the movement of the train assembly 500, the wireless device serving as the communication partner of the wireless device 200 is switched at the time calculated by the switching time determination unit 115 (S38). The communication partner is switched to the next wireless device each time the time calculated from the travel speed of the train assembly 500, the acceleration of the train assembly 500 and the distance between the wireless devices on the train assembly 500, or the time calculated from the predetermined travel speed at the installation location of the wireless device 200 on the ground and the distance between the wireless devices, with respect to the plurality of wireless devices 100, 120, 140 and 160 installed on the train assembly 500, elapses.

[0051] The switching time determination unit 115 refers to the information stored in the storage unit 116 for the distance between the wireless devices described above and the specified travel speed at the installation location of the wireless device 200. The switching time determination unit 115 also captures information specifying the travel speed and acceleration of the train assembly 500. The starting point of the switching process is the time at which the wireless device 100 first receives data. Information specifying this starting point is transmitted by ProSe Groupcast along with the information required for establishing the connection and for security authentication.

[0052] After the communication partner of wireless device 200 has switched to wireless device 120, wireless device 120 transmits the data received at wireless transceiver unit 112 from wireless device 200 to wireless device 100 via ProSe groupcast (S39). Wireless device 100 sends the received data to the vehicle's own superior device 300 (S40). When wireless device 120 sends data to wireless device 100 via ProSe groupcast, wireless devices 140 and 160 can receive data. However, wireless devices 140 and 160 that have received data from a head-mounted wireless device discard the received data (S41).

[0053] When wireless device 140 receives data from wireless device 160 at its rear via ProSe groupcast (S42), wireless device 140 forwards the data via ProSe groupcast (S43). Consequently, the data is transmitted to wireless device 100 at the front. It should be noted that information specifying the sequence of wireless devices 100, 120, 140, and 160 installed on train arrangement 500 is stored in memory unit 116, and control unit 113 refers to this information and determines whether the data should be discarded and whether the received data should be retransmitted or sent.

[0054] The effect achieved in the second embodiment is the same as the effect achieved in the first embodiment. Third example.

[0055] In the first and second embodiments, the data is transmitted from the ground to the vehicle. In the third embodiment, the data is transmitted from a wireless device in the vehicle to a wireless device on the ground via groupcast.

[0056] Fig. Figure 9 is a diagram showing a configuration of a T2X system 1B according to the third embodiment. The T2X system 1B is a wireless system with several wireless devices 700, 720, 740, and 760 installed on the ground in a row along a track, and one wireless device 600 installed on the train assembly 500. The configuration of wireless device 600, wireless device 700, wireless device 720, wireless device 740, and wireless device 760 is the same as the configuration of wireless device 100 in the first embodiment.

[0057] In the third embodiment, the wireless device 600 installed on the train assembly 500 transmits data to the several wireless devices 700, 720, 740, and 760 installed on the ground. An application example for the T2X system 1B could be a tachograph data acquisition system, in which a moving train transmits data from its tachograph, for example, to a wireless device installed at the entrance to a station area on a return conductor line. The third embodiment mainly describes the differences from the first embodiment.

[0058] If the multitude of ground-installed wireless devices 700, 720, 740 and 760 and the wireless device 600 installed on the train arrangement 500 are communicating using the proximity service, the T2X system 1B restricts only one of the multitude of ground-installed wireless devices 700, 720, 740 and 760 to being connected to the wireless device 600 installed on the train arrangement 500.

[0059] The master ground device 400 is connected to the wireless device 700. The wireless devices 700, 720, 740, and 760 are arranged along the tracks in that order, starting from the rear and proceeding in the direction of travel of the train. Each wireless device 700, 720, 740, and 760 communicates with an adjacent wireless device via ProSe unicast. Adjacent wireless devices are the wireless devices 700 and 720, 720 and 740, and 740 and 760.

[0060] Wireless device 600 is connected to the vehicle-side master device 300. Wireless device 600 communicates with wireless devices 700, 720, 740, and 760 on the ground via ProSe Layer 2 Groupcast. Although Fig. Figure 9 shows that the four wireless devices 700, 720, 740 and 760 are installed on the floor; the number of wireless devices installed on the floor only needs to be two or more. Although Fig. Figure 9 shows that wireless device 600 communicates with wireless device 720 and wireless device 740; wireless device 600 can communicate with all wireless devices on the ground within its communication range.

[0061] The operation of each device in the third embodiment is similar to the operation of each device in the one described in Fig. 5 first embodiment, except that the wireless device 200 is replaced by the wireless device 600, the wireless device 100 by the wireless device 700, the wireless device 120 by the wireless device 720, the wireless device 140 by the wireless device 740, the wireless device 160 by the wireless device 760, the superior ground device 400 by the vehicle's own superior device 300 and the vehicle's own superior device 300 by the superior ground device 400.

[0062] The T2X system 1B according to the third embodiment restricts communication to only one ground-based wireless device with the vehicle's own wireless device 600 using ProSe in ground-to-vehicle communication, thus allowing the multiple ground-based wireless devices 700, 720, 740, and 760 to transmit data without overloading the wireless bandwidth. This enables the T2X system 1B to reduce the transmission time for sending the train set 500's logbook to a wireless device installed, for example, at the entrance to a station area on a return conductor line, while the train set 500 is in motion.

[0063] As described above, the T2X system 1B according to the third embodiment is a system in which the wireless device 200 in the first embodiment is replaced by the wireless device 600, and the wireless devices 100, 120, 140, and 160 in the first embodiment are replaced by the wireless devices 700, 720, 740, and 760, respectively. That is, the T2X system 1B initially restricts communication between the multiple ground-installed wireless devices 700, 720, 740, and 760, and only the wireless device 700, which is installed furthest back in the direction of travel of the train assembly 500 and which approaches the train assembly 500 first, and which is permitted to communicate with the wireless device 600 installed on the train assembly 500.

[0064] Among the multitude of wireless devices 700, 720, 740 and 760 installed on the ground, the wireless devices 720, 740 and 760, which are different from the wireless device 700 that first approaches the train assembly 500, upon detecting the wireless device 600 installed on the train assembly 500, submit a request for permission to communicate with the wireless device 600 installed on the train assembly 500 to the wireless device 700 that first approaches the train assembly 500.Upon receiving a request for communication permission with wireless device 600, installed on train assembly 500, from a wireless device other than wireless device 700, which train assembly 500 is approaching first, wireless device 700, which is approaching train assembly 500 first, grants communication permission to the wireless device at the rear of train assembly 500 in the direction of travel, among one or more wireless devices that made the request. Of the multiple wireless devices 700, 720, 740, and 760 installed on the ground, the wireless device that received the communication permission communicates with wireless device 600, which is installed on train assembly 500.

[0065] The function, in which a wireless device of the plurality of wireless devices 700, 720, 740 and 760, installed on the ground, receives a request for permission to connect with the wireless device 600, installed on the train assembly 500, from a wireless device other than the one wireless device of the plurality of wireless devices 700, 720, 740 and 760, and then the one wireless device issues permission to connect to the wireless device at the rear end in the direction of travel of the train assembly 500, among one or more wireless devices that made the request to wireless devices, switches to the wireless devices installed at the front in the direction of travel of the train assembly 500 in the order from the wireless device 700, which the train assembly 500 first approaches, among the plurality of wireless devices 700, 720, 740 and 760,which are installed on the ground, at the following time in accordance with the movement of the train assembly 500. The time profile is a time profile calculated from the specified travel speed at the installation location of the several ground-installed wireless devices 700, 720, 740 and 760 and the installation position of the wireless device 600 installed on the train assembly 500.

[0066] When the multiple ground-installed wireless devices 700, 720, 740 and 760 and the wireless device 600 installed on the train arrangement 500 communicate using the proximity service, a first wireless device among the multiple wireless devices 700, 720, 740 and 760 notifies a second wireless device among the multiple wireless devices 700, 720, 740 and 760 with information required to establish a connection and perform security authentication with the wireless device 600 installed on the train arrangement 500.In accordance with the movement of the train arrangement 500, the wireless device communicating with the wireless device 600 installed on the train arrangement 500 is switched among the ground-installed wireless devices 700, 720, 740 and 760 at a time calculated from the specified travel speed at the installation location of the several ground-installed wireless devices 700, 720, 740 and 760 and the installation position of the wireless device 600 installed on the train arrangement 500. Fourth example.

[0067] In the third embodiment, the data from the vehicle to the ground is transmitted via ProSe groupcast between the wireless device 600 installed on the train assembly 500 and the wireless devices 700, 720, 740, and 760 on the ground. In the fourth embodiment, the data from the vehicle to the ground is transmitted via ProSe unicast between the wireless device 600 installed on the train assembly 500 and the wireless devices 700, 720, 740, and 760 on the ground.

[0068] Fig. Figure 10 is a diagram showing a configuration of a T2X system 1C according to the fourth embodiment. Wireless device 700, wireless device 720, wireless device 740, and wireless device 760 have the same ProSe UE ID and belong to the same ProSe Layer 2 group. Wireless device 600, installed on the train assembly 500, communicates with wireless device 700, wireless device 720, wireless device 740, and wireless device 760 on the ground via ProSe unicast. Although Fig. Figure 10 shows that the four wireless devices 700, 720, 740 and 760 are installed on the floor; the number of wireless devices installed on the floor only needs to be two or more. Although Fig. Figure 10 shows that wireless device 600 communicates with wireless device 740; wireless device 600 can communicate with any wireless device on the ground as long as it is within communicable range.

[0069] The operation of each device in the fourth embodiment is similar to the operation of each device in the one described in Fig.8 shown second embodiment, except that the wireless device 200 is replaced by the wireless device 600, the wireless device 100 by the wireless device 700, the wireless device 120 by the wireless device 720, the wireless device 140 by the wireless device 740, the wireless device 160 by the wireless device 760, the superior ground device 400 by the vehicle's own superior device 300 and the vehicle's own superior device 300 by the superior ground device 400.

[0070] The effect achieved in the fourth embodiment is the same as the effect achieved in the third embodiment.

[0071] The configurations described in the exemplary embodiments listed above are examples. These embodiments can be combined with each other and with other well-known techniques, and some of the configurations can be omitted or modified to an extent that does not deviate from the core idea of ​​the present invention. REFERENCE MARK LIST

[0072] 1, 1A, 1B, 1C T2X system; 100, 120, 140, 160, 200, 600, 700, 720, 740, 760 wireless device; 101 wireless interface termination unit; 102 memory; 103 CPU; 104 wired interface termination unit; 105 power supply circuit; 106 processing circuit; 111 wired transceiver; 112 wireless transceiver; 113 control unit; 114 link permission response determination unit; 115 switching time determination unit; 116 storage unit; 300 vehicle-side superior device; 400 ground-side superior device; 500 train assembly.

Claims

Wireless system (1, 1A), comprising: a wireless device (200) installed on the ground along a track; and a plurality of wireless devices (100, 120, 140, 160) installed in a train (500) in a series from one end to the rear of the train (500), wherein if the ground-installed wireless device (200) and the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) perform communication using a proximity service, a restriction is imposed such that only one of the plurality of wireless devices (100, 120, 140, 160) is connected to the ground-installed wireless device (200), from the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) the wireless device not installed at the front in the direction of travel of the train (500). (120, 140,160) upon detection of the wireless device (200) installed on the ground, a request for permission to communicate with the wireless device (200) installed on the ground to the wireless device (100) installed at the front of the train (500) in the direction of travel is made from among the multitude of wireless devices (100, 120, 140, 160); upon receiving the request for permission to communicate with the wireless device (200) installed on the ground from the wireless device (120, 140, 160) not installed at the front, the wireless device (100) installed at the front of the train (500) grants permission to communicate with the wireless device that is installed at a position nearest to the front of the train (500) in the direction of travel, from among one or more wireless devices (120, 140, 160) that made the request, and from the multitude of the in the train (500) installed wireless devices (100, 120, 140,160) the wireless device that has been granted permission to connect communicates with the wireless device (200) installed on the ground. Wireless system (1, 1A) according to claim 1, wherein a function in which a wireless device from the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) receives a request for permission to connect with the wireless device (200) installed on the ground from a wireless device other than the one wireless device from the plurality of wireless devices (100, 120, 140, 160) and then grants permission to connect to the wireless device installed at a position closest to the head of the train (500) in the direction of travel, among one or more wireless devices (100, 120, 140, 160) that made the request, from the wireless device (100) installed at the head of the train (500) in the direction of travel. (100, 120, 140,160) is successively transmitted to the subsequent wireless devices in accordance with the movement of the train (500) at a time calculated from a speed of the train (500), an acceleration of the train (500) and a distance between adjacent wireless devices of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500), or at a time calculated from a specific travel speed at an installation location of the ground-mounted wireless device (200) and an installation position of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500). Wireless system (1, 1A) comprising: a wireless device (200) installed on the ground along a track; and a plurality of wireless devices (100, 120, 140, 160) installed in a train (500) in a series from one end to the rear of the train (500), wherein a first wireless device from the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) notifies a second wireless device from the plurality of wireless devices (100, 120, 140, 160) of information necessary for establishing the connection and performing security authentication with the wireless device (200) installed on the ground, and in accordance with the movement of the train (500) at a time determined from a speed of the train (500),a train's acceleration (500) and a distance between adjacent wireless devices of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) is calculated, or at a time calculated from a specific travel speed at an installation location of the ground-installed wireless device (200) and an installation position of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500), the wireless device communicating with the ground-installed wireless device (200) is switched among the plurality of wireless devices (100, 120, 140, 160) installed in the train (500). Ground-to-vehicle transmission method for a wireless system (1, 1A) comprising a wireless device (200) installed on the ground along a track and a plurality of wireless devices (100, 120, 140, 160) installed in a train (500) in a series from one end to the rear of the train (500), wherein the ground-to-vehicle transmission method comprises: a step in which, when the ground-installed wireless device (200) and the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) are communicating, a restriction is imposed such that only one of the plurality of wireless devices (100, 120, 140, 160) is connected to the ground-installed wireless device (200);a step in which, from the multitude of wireless devices (100, 120, 140, 160) installed in the train (500), the wireless device (120, 140, 160) which is not installed at a head in the direction of travel of the train (500), upon detection of the wireless device (200) installed on the ground, makes a request for permission to connect with the wireless device (100) installed at the head in the direction of travel of the train (500) from the multitude of wireless devices (100, 120, 140, 160);a step in which, after receiving the request for communication permission from the wireless device (200) installed on the ground, the wireless device (100) installed on the head in the direction of travel of the train (500) grants communication permission from the wireless device (120, 140, 160) not installed on the head to the wireless device that is installed at a position closest to the head in the direction of travel of the train (500) among one or more wireless devices (120, 140, 160) that made the request; and a step in which, of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500), the wireless device that received the communication permission communicates with the wireless device (200) installed on the ground. Ground-to-vehicle transmission method according to claim 4, wherein the wireless device (200) installed on the ground and the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) perform data communication and request for connection permission at different times using the scheduling of the proximity service. Ground-to-vehicle transmission method for a wireless system (1, 1A) comprising a wireless device (200) installed on the ground along a track and a plurality of wireless devices (100, 120, 140, 160) installed in a train (500) in a series from one end to the rear of the train (500), wherein the ground-to-vehicle transmission method comprises: a step in which, when the plurality of wireless devices (100, 120, 140, 160) installed in the train (500) and the ground-installed wireless device (200) are communicating using a proximity service, a first wireless device from the plurality of wireless devices (100, 120, 140, 160) is selected to transmit a second wireless device from the plurality of wireless devices (100, 120, 140, 160). 140, 160) notified about information,which are required for establishing the connection and performing security authentication with the wireless device (200) installed on the ground; and a step in which, in accordance with the movement of the train (500), at a time calculated from a speed of the train (500), an acceleration of the train (500) and a distance between adjacent wireless devices of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500), or at a time calculated from a certain travel speed at an installation location of the ground-installed wireless device (200) and an installation position of the plurality of wireless devices (100, 120, 140, 160) installed in the train (500), the wireless device that communicates with the ground-installed wireless device (200) among the plurality of wireless devices (100, 120, 160) installed in the train (500)140, 160) is switched. Wireless system (1B, 1C), comprising: a variety of wireless devices (700, 720, 740, 760) installed on the ground in a row along a track; and a wireless device (600) installed in a train (500), wherein when the plurality of ground-installed wireless devices (700, 720, 740, 760) and the wireless device (600) installed in the train (500) communicate using the proximity service, a restriction is imposed such that only one of the plurality of wireless devices (700, 720, 740, 760) is connected to the wireless device (600) installed in the train (500), from the plurality of ground-installed wireless devices (700, 720, 740, 760), the wireless device (720, 740, 760) that differs from the wireless device (700) to which the train (500) first approaches,Upon detecting the wireless device (600) installed in the train (500), a request for communication permission is sent to the wireless device (700) that the train (500) is approaching first from among the multiple wireless devices (700, 720, 740, 760). Upon receiving the request for communication permission from the wireless device (600) installed in the train (500), the wireless device (720, 740, 760) that differs from the wireless device (700) that the train (500) is approaching first is granted communication permission to the wireless device (700) that the train (500) is approaching first. The wireless device (700) that the train (500) is approaching first is granted communication permission to the wireless device that is furthest back in the direction of travel of the train (500), among one or more wireless devices (720, 740, 760), who made the request, granted and from the multitude of wireless devices installed on the ground (700, 720, 740,760) the wireless device that has been granted permission to connect communicates with the wireless device (600) installed in the train (500). Wireless system (1B, 1C) according to claim 7, wherein a function in which a wireless device of the plurality of ground-installed wireless devices (700, 720, 740, 760) receives a request for permission to connect with the wireless device (600) installed in the train (500) from a wireless device other than the one wireless device of the plurality of wireless devices (700, 720, 740, 760), and then grants permission to connect to the wireless device installed furthest aft in the direction of travel of the train (500) below one or more wireless devices (720, 740, 760) that made the request, to the wireless devices installed on the front of the train (500) in the direction of travel, in the order from the wireless device (700),the train (500) first approaches under the plurality of ground-installed wireless devices (700, 720, 740, 760) is transmitted in accordance with the movement of the train (500) at a time calculated from a specific speed at an installation location of the plurality of ground-installed wireless devices (700, 720, 740, 760) and an installation position of the wireless device (600) installed on the train (500). Wireless system (1B, 1C) comprising: a variety of wireless devices (700, 720, 740, 760) installed on the ground in a row along a track; and a wireless device (600) installed in a train (500), wherein when the plurality of ground-installed wireless devices (700, 720, 740, 760) and the wireless device (600) installed in the train (500) communicate using a proximity service, a first wireless device from the plurality of wireless devices (700, 720, 740, 760) notifies a second wireless device from the plurality of wireless devices (700, 720, 740, 760) of information necessary for establishing the connection and performing security authentication with the wireless device (600) installed in the train (500), and in accordance with the movement of the train (500) at a time,The wireless device that communicates with the wireless device (600) installed on the train (500) is switched among the multiple wireless devices (700, 720, 740, 760) installed on the ground, calculated from a predetermined travel speed at an installation location of the multiple ground-installed wireless devices (700, 720, 740, 760) and an installation position of the wireless device (600) installed on the train (500). Ground-to-vehicle transmission method for a wireless system (1B, 1C) comprising a plurality of wireless devices (700, 720, 740, 760) installed on the ground in a row along a track and a wireless device (600) installed in a train (500), wherein the ground-to-vehicle transmission method comprises: a step in which, when the plurality of ground-installed wireless devices (700, 720, 740, 760) and the wireless device (600) installed in the train (500) are communicating using the proximity service, a restriction is imposed such that only one of the plurality of ground-installed wireless devices (700, 720, 740, 760) is connected to the wireless device (600) installed in the train (500);a step in which, from the multitude of wireless devices (700, 720, 740, 760) installed on the ground, the wireless device (720, 740, 760) that differs from the wireless device (700) which the train (500) first approaches, upon detection of the wireless device (600) installed in the train (500), makes a request for permission to connect with the wireless device (600) installed in the train (500) to the wireless device (700) which the train (500) first approaches;a step in which, upon receiving the request for communication permission with the wireless device (600) installed in the train (500), the wireless device (720, 740, 760), which is different from the wireless device (700) that the train (500) is approaching first, grants communication permission to the wireless device that is furthest behind the train (500) in the direction of travel, among one or more wireless devices (720, 740, 760) that made the request; and a step in which, of the multitude of wireless devices (700, 720, 740, 760) installed on the ground, the wireless device that received the communication permission communicates with the wireless device (600) installed in the train (500). Ground-to-vehicle transmission method according to claim 10, wherein the plurality of wireless devices installed on the ground (700, 720, 740, 760) and the wireless device installed in the train (500) perform data communication and query the connection permission at different times using the scheduling of the proximity service. Ground-to-vehicle transmission method for a wireless system (1B, 1C) comprising a plurality of wireless devices (700, 720, 740, 760) installed on the ground in a row along a track, and a wireless device (600) installed in a train (500), wherein the ground-to-vehicle transmission method comprises: a step in which, when the plurality of ground-installed wireless devices (700, 720, 740, 760) and the wireless device (600) installed in the train (500) are communicating using a proximity service, a first wireless device from the plurality of wireless devices (700, 720, 740, 760) transmits information to a second wireless device from the plurality of wireless devices (700, 720, 740, 760). notifiedwhich are necessary for establishing the connection and performing security authentication with the wireless device (600) installed on the train (500); and a step in which, in accordance with the movement of the train (500), at a time calculated from a predetermined speed at an installation location of the plurality of ground-installed wireless devices (700, 720, 740, 760) and an installation position of the wireless device (600) installed on the train (500), the wireless device communicating with the wireless device (600) installed on the train (500) is switched among the multiple ground-installed wireless devices (700, 720, 740, 760).

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