Railway communication system and railway communication method

Abstract

In ground-to-vehicle communication on railways, while an increase in applications related to communication and an increase in communication volume are expected, in order to solve the problem of high cost when communication equipment is installed for each application as a railway communication system that uses the same wireless network to transmit data from a plurality of applications between ground equipment and on-board equipment, an on-board wireless control unit provided in the on-board equipment has a function of monitoring a communication environment, a function of setting transmission priority for each of the plurality of applications, and a function of performing data packet control on the basis of the communication environment and the transmission priority.

Description

[Technical Field]

[0001] The present invention relates to a railway communication system and a railway communication method for controlling communication between ground equipment and on-board equipment. [Background technology]

[0002] As high-speed, high-capacity communications environments are being developed, the spread of 5G and other technologies is expected to lead to an increase in communications volume in ground-to-car communications on railways. At the same time, there is a need to reduce communications equipment from a cost perspective. Therefore, there are high expectations for technology that can transmit large amounts of data at lower cost, even in ground-to-car communications on railways.

[0003] Furthermore, as a specific prior art document, Patent Document 1 discloses a technology for a railway facility monitoring system in which data with low priority is not transmitted as a data reduction process when wireless communication is unavailable.

[0004] Patent document 2 discloses a technology in a train radio system that selects high-priority data when a moving body is located in an area with a poor radio environment, and gives high redundancy to the selected high-priority data.

[0005] Patent Document 3 discloses a technology in which information to be transmitted wirelessly or via wired communication is categorized into multiple stages and transmitted at an information transmission timing according to each category. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-166217 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-123904 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-268026 Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional ground-to-vehicle communications, a dedicated line is set up for each application, and communication is carried out separately for each application. In this case, wireless communication equipment is required for each application, which leads to issues such as an increase in the number of equipment and maintenance costs. Therefore, an object of the present invention is to provide a technology that ensures communication of high-priority applications even when the communication environment deteriorates, without increasing the amount of equipment. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, one representative railway communication system of the present invention is a railway communication system that transmits data by a plurality of applications between ground equipment and on-board equipment using the same wireless network, and the on-board wireless control unit provided in the on-board equipment has a function of monitoring the communication environment, a function of setting transmission priority for each of the plurality of applications, and a function of performing data packet control based on the communication environment and the transmission priority, and the function of setting transmission priority for each of the plurality of applications is performed within each application. setting will be The events covered by the application This function reflects the status in real time and sets the transmission priority for each application. [Effects of the Invention]

[0009] According to the present invention, it is possible to reduce the number of lines required for each application, and also to ensure communication for high-priority applications even when the communication environment deteriorates. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a railway communication system according to the present invention. [Figure 2] 2 is a diagram illustrating an example of a configuration and information flow in an on-board radio control unit according to the first embodiment. FIG. [Figure 3] 1 is a diagram showing an environment in which a personal terminal is involved in a railway communication system according to the present invention; [Figure 4] FIG. 10 is a diagram illustrating an example of a configuration and information flow within an on-board radio control unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, as modes for carrying out the present invention, Examples 1 to 3 will be described with reference to the drawings. Note that the present invention is not limited to these Examples. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals. [Example]

[0012] 1 is a schematic diagram showing an example of the configuration of a railway communication system according to the present invention, which is a system for transmitting a plurality of applications between ground and railcars using the same wireless system.

[0013] In the example configuration shown in Fig. 1, four types of applications related to train control 1, voice communication 2, on-board content 3, and on-board equipment video monitoring 4 are transmitted over the same wireless system. The four types of applications are provided in wayside equipment 5 and on-board equipment 6, respectively.

[0014] Here, we will give an overview of the four types of applications: Train Control 1 is a safety application related to train operation control (described later); Voice Call 2 is an application related to voice calls such as conversations between crew members and in-car announcements; On-board Content 3 is an application related to content for display on in-car displays, etc.; and On-board Equipment Video Monitoring 4 is an application related to video monitoring of on-board equipment, etc. (described later).

[0015] Furthermore, although four types of applications have been given as examples, other applications may be adopted without being limited to the above four types, and four types are not required, as long as two or more types of applications are targeted.

[0016] Regarding the wayside equipment 5 and the on-board equipment 6, separate devices are configured for each application in FIG. 1, but they may be devices common to multiple applications.

[0017] Data transmission from the four types of applications is carried out via a ground wireless control unit 7 and an on-board wireless control unit 8. The wireless control units are provided on the ground and on the train, and are devices that receive transmission information from multiple applications via wired connections and control wireless transmission packets.

[0018] The wireless system that transmits the transmission packets created by the wireless control unit uses a public wireless network 9. Alternatively, a private wireless network 9 may be used as the wireless system. Here, the private wireless network is expected to be provided in areas where communication facilities are not well developed and the public wireless network is unstable. Furthermore, the public wireless network 9 and the private wireless network 9 may be used in combination.

[0019] Next, the operation of the first embodiment will be described using the transmission system shown in FIG. In the first embodiment, communication from the on-board side to the ground side will be described. Note that the communication from the ground side to the on-board side of the vehicle also operates in the same manner as the communication from the on-board side to the ground side.

[0020] First, each of the four types of applications shown in Fig. 1 is assigned a transmission priority (hereinafter simply referred to as "priority"). The on-board radio control unit 8 receives data packets (hereinafter referred to as "application packets" or simply "app packets") sent from each application from the on-board equipment 6, and controls the packets based on the priority of each application (hereinafter referred to as "application priority") and the communication environment. For example, when the communication environment deteriorates, data from applications with low application priority is excluded from transmission, and processing is performed to cancel packet transmission.

[0021] Next, a specific operation mode of the on-board radio control unit 8 according to the first embodiment will be described. 2 is a diagram illustrating an example of the configuration and information flow within the on-board wireless control unit 8 according to Example 1. The on-board wireless control unit 8 includes at least an application input unit 10, an application information control unit 11, a communication environment monitoring unit 12, and a packet control unit 13.

[0022] The application input unit 10 transmits application packets (application packets) sent from each of four types of applications related to train control 1, voice call 2, on-board content 3, and on-board equipment video monitoring 4 to the application information control unit 11 and packet control unit 13.

[0023] The application information control unit 11 refers to the contents of the received application packet. To this end, the application information control unit 11 sets in advance, for each application, one or more bits to be referred to in the application packet (hereinafter referred to as "reference bits").

[0024] Furthermore, the application information control unit 11 determines and outputs the application priority based on the value of the reference bit in the received application packet. Alternatively, the application information control unit 11 may set a condition for determining the application priority based on the value of this reference bit, or conversely, may uniformly determine the application priority based on the type of application without providing a reference bit.

[0025] The communication environment monitoring unit 12 constantly monitors the communication environment of the wireless network 9 and outputs information relating to the communication environment (hereinafter referred to as "communication environment information"). Specific examples of the communication environment monitored by the communication environment monitoring unit 12 include RTT (Round Trip Time), packet loss rate, and received radio wave intensity.

[0026] Packet control unit 13 controls the transmission of application packets and outputs transmission packets based on the application priority output by application information control unit 11 and the communication environment information output by communication environment monitoring unit 12. In the first embodiment, packet control unit 13 determines whether or not to transmit application packets based on the application priority and the communication environment information, and when packet control unit 13 receives information indicating that the communication environment has deteriorated from the communication environment information, it outputs only application packets with high application priority as transmission packets.

[0027] A specific example of a deterioration in the communication environment is a congestion of communication due to a personal terminal for general use (such as a smartphone). FIG. 3 is a diagram showing an environment in which a personal terminal (such as a smartphone) is involved in a railway communication system according to the present invention. In the railway communication system according to the present invention, a public wireless network is used for the wireless system, and as shown in FIG. 3, a personal terminal for general use (such as a smartphone) 14 is also connected to the same public wireless network and uses a line. Therefore, the involvement of these personal terminals increases the possibility of line congestion and a deterioration in the communication environment. Since the communication environment is considered to be constantly changing due to the movement of a train while it is running, monitoring the communication environment is important in a railway communication system.

[0028] Next, the procedure for setting priority levels for each application in the application information control unit 11 will be described using a specific application as an example. As exemplary applications, on-board equipment video monitoring 4 and train control 1 are taken up.

[0029] First, the application for on-board equipment video monitoring 4 is an application that monitors on-board equipment such as bogies and motors with video, judges the monitored video, and transmits information such as whether the on-board equipment is normal or abnormal.

[0030] For this application, the application information control unit 11 provided in the on-board radio control unit 8 sets in advance, as a reference bit, a bit that governs whether the on-board equipment is normal or abnormal in the application related to on-board equipment video monitoring 4. In other words, the application related to on-board equipment video monitoring 4 can set the reference bit to reflect in real time whether the on-board equipment is normal or abnormal.

[0031] When the on-board equipment is normal, as indicated by this reference bit, the priority is set to "low" taking into consideration the volume of video data. On the other hand, when the on-board equipment is abnormal, as indicated by this reference bit, the priority is set to "high." In other words, the application for on-board equipment video monitoring 4 can set the application priority by reflecting the normality or abnormality of the on-board equipment in the reference bit in real time.

[0032] The other application, related to train control 1, is a safety-related application that controls train operation, such as CBTC (Communications-Based Train Control). Because this application is a safety-related application, the priority is always set to "high" regardless of the application state. Therefore, the application information control unit 11 always sets the priority to "high" for application packets from this train control 1.

[0033] As described above, in the first embodiment, even when the communication environment deteriorates, ground-to-vehicle transmission in both of the above-mentioned applications can be ensured. [Example]

[0034] In the first embodiment, the priority was set based on the reference bit in the application, but it may be changed depending on the train position or the operating section of the vehicle. In the second embodiment of the present invention, the priority is set based on the train position or the operating section of the vehicle.

[0035] 4 is a diagram showing an example of the configuration and information flow in the on-board radio control unit 8 according to the embodiment 2. In the embodiment 2, compared to the previous embodiment 1, an application information DB (database) is added to the on-board radio control unit 8, and train position information is also taken in from the ground coil 16.

[0036] The application information DB 15 stores information on the priority of each application that is set in advance in correspondence with the train position. Furthermore, the priority information of each application may be set in correspondence with the operating section of the vehicle and stored in the application information DB 15.

[0037] The application information control unit 11 receives the application priority information from the application information DB 15 and the train position information from the ground coil 16 as input, and determines the priority of the application from the contents of the application information DB 15 and the actual train position.

[0038] On the other hand, if train position information is present in the application packet transmitted between ground and railcars, the train position may be referenced from this train position information rather than from the ground coil 16. Also, the train position information in the application packet and the train position information from the ground coil 16 may be used together.

[0039] As a result, in the second embodiment, it is possible to ensure the transmission of application packets between ground and trains, not only in the event of a deterioration in the communication environment, but also in response to regional train operation characteristics using train positions and vehicle operating sections. [Example]

[0040] In the third embodiment of the present invention, when the communication environment deteriorates, the transmission interval (transmission cycle) of a low-priority application is changed instead of excluding the low-priority application from the transmission target as in the first and second embodiments. Specifically, the packet control unit 13 shown in Fig. 2 controls the transmission interval (transmission cycle) of this application.

[0041] That is, when the communication quality of the communication environment is below a predetermined quality, the packet control unit 13 widens (increases) the transmission cycle of the application with low priority and outputs the transmission packets sparsely. Also, the interval of the transmission cycle may be changed according to the priority, and the lower the priority, the wider (longer) the transmission cycle may be controlled.

[0042] As a result, in the third embodiment, even when the communication environment deteriorates, it is possible to ensure ground-to-vehicle transmission of high-priority application packets.

[0043] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0044] 1: Train control (application name), 2: Voice call (application name), 3: On-board content (application name), 4: On-board equipment video monitoring (application name), 5: Ground equipment, 6: On-board equipment, 7: Ground wireless control unit, 8: On-board wireless control unit, 9: Wireless network (public), 10: Application input unit, 11: Application information control unit, 12: Communication environment monitoring unit, 13: Packet control unit, 14: Personal terminal (smartphone, etc.), 15: Application information DB, 16: Ground coil

Claims

1. A railway communication system that transmits data by a plurality of applications between ground equipment and on-board equipment using the same wireless network, The on-board wireless control unit provided in the on-board equipment includes: a function of monitoring a communication environment, a function of setting a transmission priority for each of the plurality of applications, and a function of performing packet control of the data based on the communication environment and the transmission priority; The function of setting transmission priority for each of the plurality of applications is a function of setting transmission priority for each of the applications by reflecting in real time the state of an event that is a target of the application and that is set in advance for each of the applications. A railway communication system characterized by:

2. A railway communication system that transmits data by a plurality of applications between ground equipment and on-board equipment using the same wireless network, The on-board wireless control unit provided in the on-board equipment includes: a function of monitoring a communication environment, a function of setting a transmission priority for each of the plurality of applications, and a function of performing packet control of the data based on the communication environment and the transmission priority; The function of setting the transmission priority for each of the plurality of applications is a function of setting the transmission priority for each of the applications according to the running position of a vehicle equipped with the on-board equipment or the operating section on which the vehicle runs. A railway communication system characterized by:

3. 3. The railway communication system according to claim 1, The wireless network is a public wireless network. A railway communication system characterized by:

4. 3. The railway communication system according to claim 1, The function of controlling packets of data based on the communication environment and the transmission priority is a function of canceling transmission of data with a low transmission priority when the communication environment deteriorates. A railway communication system characterized by:

5. 3. The railway communication system according to claim 1, The function of controlling packets of data based on the communication environment and the transmission priority is a function of increasing the transmission cycle of data with a low transmission priority when the communication environment deteriorates. A railway communication system characterized by:

6. 3. The railway communication system according to claim 1, The plurality of applications include at least one of an application for monitoring, by video, whether on-board equipment of a vehicle equipped with the on-board equipment is normal or not, and a safety application for controlling the operation of a train including a vehicle equipped with the on-board equipment. A railway communication system characterized by:

7. A railway communication method for transmitting data by a plurality of applications between a ground facility and an on-board facility using the same wireless network, comprising: The on-board wireless control unit provided in the on-board equipment monitors the communication environment, sets the transmission priority for each of the plurality of applications in real time, reflecting the state of an event targeted by the application that is set within each of the plurality of applications, and performs packet control of the data based on the communication environment and the transmission priority. A railway communication method characterized by:

8. A railway communication method for transmitting data by a plurality of applications between a ground facility and an on-board facility using the same wireless network, comprising: The on-board wireless control unit provided in the on-board equipment monitors the communication environment, sets transmission priorities for each of the plurality of applications according to the running position of the vehicle on which the on-board equipment is mounted or the operating section in which the vehicle is running, and performs packet control of the data based on the communication environment and the transmission priorities. A railway communication method characterized by:

9. 9. The railway communication method according to claim 7 or 8, The data packet control stops transmission of the data with low transmission priority when the communication environment deteriorates. A railway communication method characterized by:

10. 9. The railway communication method according to claim 7 or 8, The data packet control increases the transmission cycle of the data with low transmission priority when the communication environment deteriorates. A railway communication method characterized by:

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