JP2007081766A - Method and device for ground-vehicle communication in railroad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for ground/vehicle communication in a railroad capable of excellently transmitting data, by performing high-speed communication by using an overhead wire and rails of the railroad as a communication path. <P>SOLUTION: A plurality of power line carrier modems 4a, 4b connected to a router 3 are arranged on the ground in the premise of a station. The modem for performing communication is selected between the power line carrier modems 4a, 4b arranged on the ground based on SN ratio (the ratio of a signal to noise) information between the power line carrier modems 4a, 4b on the ground and a power line carrier modem 9 on a vehicle. Then communication is performed between the router 3 and the power line carrier modem 9 on the vehicle via the selected power line carrier modem. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a railway ground / train-to-train communication method and apparatus for transmitting data using railway overhead lines and rails as communication paths.

  In the railway field, there is a need to transmit operation information and business support information to vehicles, and a communication method using wireless has been proposed. However, since high confidentiality is required for operation information and the like, wired communication is desired rather than wireless communication that is easy to intercept.

  As a conventional technique, as described in [Patent Document 1] and [Patent Document 2], there is a wired communication method using an overhead wire and a rail as a communication path.

  In [Patent Document 1], a substation is connected to a transformer connected to the Internet, etc., a transformer that steps down the voltage from a high-voltage transmission line and sends power to the overhead line through the transmission line, and the router. The power line carrier modem relays the exchange of communication signals between the two, and the train is connected between the pantograph that receives the power sent from the substation through the overhead line and the network in the train, and the communication signal between the two A wired mobile communication method provided with a power line carrier modem that relays the exchange of data is described.

  In [Patent Document 2], a vehicle and a facility outside the vehicle / inter-vehicle communication device are installed, and the communication device installed in the vehicle is connected to a power line that supplies power to the vehicle via a current collector and a rail. The communication device installed in the outside facility is connected to a feeder, trolley wire, or a power line that supplies power between the third rail and the rail, and between the communication device, the wire, trolley wire, or between the third rail and the rail. Is used as a communication line, and the transmission data is assigned to each carrier signal for communication. The communication device installed in the facility outside the vehicle is installed in a station premises, a station building, or a vehicle inspection site, and at least an image. Information that is displayed on a display device for passengers or a crew member installed in a vehicle, or that transmits maintenance information used for vehicle inspection or maintenance. Device is described.

Japanese Patent Laid-Open No. 11-317697 JP 2004-312410 A

  In the communication method described in [Patent Document 1], a ground power line carrier modem is installed in a substation, but the distance between substations is about 3 to 5 km in an urban area and 20 km or more in a suburb. As a result of simulating the attenuation characteristics, it was found that the attenuation of the communication signal is very severe and it is difficult to perform high-speed communication. Especially when receiving business support information and operation information in a centralized manner while stopping at a station or traveling at low speed, a transmission speed of several Mbps or more may be required, and a power line carrier modem is installed at the substation. However, there is a problem that a communication speed of only about several kbps can be obtained.

  In the communication method described in [Patent Document 1], the roaming function is used as a procedure for switching the power line carrier modem for communication. In the general roaming method, the reception level of the modem transmission signal is measured, and a modem with a higher reception level is selected and communicated. However, in the case of railways, inverter noise is superimposed on the communication path. There is a problem that the modem cannot be switched accurately because the reception level of the communication signal cannot be measured.

  In the off-vehicle facility / inter-vehicle communication device described in [Patent Document 2], the off-vehicle facility / inter-vehicle communication device is installed in a place such as a station premises, a station building, or a vehicle inspection site, and the S / N evaluation is performed. Although the communication is performed by changing the carrier frequency based on the result, the SN ratio of the facility outside the vehicle and the inter-vehicle communication device that is installed changes depending on the position of the moving vehicle, so the SN ratio deteriorates. There is a problem that even if the communication speed is lowered, the communication speed must be reduced.

  An object of the present invention is to provide a railway ground-to-train communication method and apparatus that enables high-speed communication by using railway overhead lines and rails as communication paths, and transmits data satisfactorily.

  In order to achieve the above object, a railway ground-to-train communication method and apparatus according to the present invention includes a plurality of power line carrier modems connected to a router on the ground in a station premises, Based on the SN ratio (signal-to-noise ratio) information between the power line carrier modems, a modem to be communicated is selected from a plurality of power line carrier communication modems installed on the ground, and the router and the vehicle are selected via the selected power line carrier modems. It communicates between the upper power line carrier modems.

  According to the present invention, even in a communication system with a relatively large attenuation using an overhead line and a rail as a communication path, a plurality of modems are installed in a relatively short section of a station premises, and a modem with a high SN ratio is selected. Since communication is performed, high-speed communication is possible. Even if inverter noise is superimposed, the power line carrier modem with the highest S / N ratio is selected from the calculation result of the S / N ratio, so that the communication state can be kept good and more stable and high-speed communication is possible. .

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a railway ground / train-to-train communication device according to the present embodiment, FIG. 2 is a flowchart showing processing at the time of communication, and FIG. 3 is a diagram for explaining a relationship with an SN ratio when a train moves. FIG. 4 is a flowchart showing another communication process.

  As shown in FIG. 1, on the ground side, power line carrying modems 4 a and 4 b are installed at a plurality of locations in the station premises, and the power line carrying modems 4 a and 4 b are connected to the router 3 via the LAN cable 2. The power line carrying modems 4a and 4b communicate with the router 3 according to a standard communication standard. The interval at which the power line carrying modems 4a and 4b are installed is suitably several tens of meters to 100 meters, but may be 200 to 400 meters in consideration of a change in the train configuration. In some cases, the distance is about 1 km in consideration of the position of the branch point in the station.

  The power line carrying modems 4a and 4b are connected to the overhead line 6 via a coupler (not shown), and are also connected to the rail 7. The overhead line 6 is applied with a high voltage of 800V or 1500V in the case of direct current and 15000V or 3000V in the case of alternating current, and a coupler is provided to cope with the high voltage, but is coupled to the power line carrying modems 4a and 4b. This is not necessary if a vessel is provided. The router 3 is connected to the computer 1 via the LAN cable 2 and connected to the external network 10 or the network 10 owned by the railway company via the LAN cable 2. As the computer 1, a personal computer (PC) can be used.

  In the train 13, a power line carrying modem 9 is installed on the vehicle, and is connected to the overhead line 6 through a coupler (not shown) and the pantograph 5 by a power line cable. However, when the power line carrying modem 9 is provided with a coupler as described above, the coupler is not necessary. The power line carrying modem 9 is connected to a terminal 11 on the vehicle and communicates with a standard communication standard. The power line carrying modem 9 is connected to the rail 7 through a wheel 12 by a power line cable. The power line cable has a motor (not shown) for driving the wheel 12, an inverter 8 for driving the motor, and a device used in the vehicle. A transformer used as a power source is connected.

  In the example shown in FIG. 1, a communication path is formed between the power line carrying modems 4 a and 4 b, the overhead line 6, the power line carrying modem 9, and the rail, but for supplying power called a third rail instead of the overhead line 6. When using a rail, a communication path is formed using a 3rd rail as a communication line.

  In the power line carrier modems 4a, 4b, and 9, communication signals having excellent noise resistance are used, and, for example, OFDM (Othogonal Frequency Division Multiplexing) or a direct spread spectrum system is used. OFDM is a method of allocating data to a plurality of carriers in a communication band and performing communication. When the noise spectrum has frequency characteristics such as inverter noise, the amount of data allocated to a carrier having a high noise level is reduced. This is a communication system that is excellent in noise resistance and capable of high-speed transmission because the high-speed performance is improved by increasing the number of allocated data for a carrier wave in a band with a low noise level.

  The operation of the railway ground / train-to-train communication device configured as described above will be described. Data transmitted via the computer 1 or the network 10 is received by the router 3. The router 3 confirms the transmission destination of the received data, and when the transmission destination is the terminal 11 on the vehicle, the router 3 selects one of the power line carrier modems 4a and 4b on the ground and transmits the data.

  When the router 3 communicates with the power line carrier modem 9 on the vehicle, which of the power line carrier modems 4a and 4b communicates is determined by the flowchart shown in FIG. Here, what is shown in parentheses in FIG. 2 is a device for performing the processing. The power line carrier modem 4a corresponds to the modem 1, the power line carrier modem 4b corresponds to the modem 2, and the power line carrier modem 9 corresponds to the modem 3. ing.

Data including a command for obtaining an S / N ratio between modems is transmitted from the router 3 to each modem. When the train 13 enters the communicable area of the ground power line carrying modems 4 a and 4 b, the modem 1 transmits a training signal to the modem 3 in step 51.

  Here, the training signal has a transmission format that is distinguished from normal data, and is training data determined in advance for evaluating the S / N ratio between the modems. This is a known communication signal in which the power line carrying modem shares the content of the communication signal.

  In step 52, the modem 3 receives the training signal and calculates the S / N ratio. Since the received training signal is known, the SN ratio can be calculated because the difference between the demodulated signal point position and the expected value is a noise component. In step 53, the S / N ratio information obtained in step 52 is transmitted to the modem 1, and in step 54, the modem 1 which has received the S / N ratio information is sent to the router 3 between the modem 1 and the modem 3 in step 55. Is reported as information on the S / N ratio.

  In step 56 to step 60, information on the SN ratio between the modem 2 and the modem 3 obtained in the same manner as in step 51 to step 55 is notified to the router 3. In step 61, the router 3 selects a combination having the highest S / N ratio based on the information on the two S / N ratios received in steps S55 and S60, and creates a routing table. At this time, referring to the information of the SN ratio obtained a plurality of times in the past, the one having the highest average value may be selected, and the one having the smallest deviation, that is, the one having the most stable SN ratio is selected. May be. For example, when the modem 1 is selected as the modem having the highest S / N ratio as a result of executing Steps 51 to 60, a routing table is created so that data addressed to the terminal 11 on the vehicle passes through the modem 1. When the routing table is created, in step 62, data is transmitted and received between the computer 10 or the network 10 owned by the railway company and the terminal 11 on the vehicle.

  In order to add a function of creating or updating a routing table from information on the S / N ratio sent from the power line carrier modems 4a and 4b, in addition to the routing table management function of a general router, the router 3 Firmware or software is installed in advance.

  In step 63, it is determined whether or not the set time has elapsed, or whether or not the number of communication errors exceeds the set value, and it is determined that the set time has elapsed by measuring the elapsed time. In this case, or when it is determined that the number of communication errors exceeds the set value by counting the number of communication errors, the process returns to step 51 and steps 51 to 62 are executed again. The time to be set is 1 second if it is short, and 60 seconds if it is long, and a value between 1 second and 60 seconds may be set.

  Here, by providing step 63, as will be described later, the SN ratio between the power line carrying modems changes depending on the movement of the train 13 or the operating condition of the inverter, but this can correspond to the change in the SN ratio. it can.

  Data received by any of the ground power line carrier modems 4a, 4b is converted into a communication signal that can be communicated between the power line carrier modems 4a, 4b, 9 and transmitted to the overhead line 6 and the rail 7. The transmitted communication signal reaches the power line carrying modem 9 on the vehicle through the overhead line 6 and the rail 7 through the pantograph 5 and the wheel 12. The power line carrying modem 9 on the vehicle converts the received signal into a standard communication standard such as USB (R) or Ether (R) and transmits it to the terminal 11 on the vehicle. At this time, the contents of the created routing table are also transmitted, and information on the power line carrier modem on the ground to be communicated is notified to the terminal 11 on the vehicle.

  On the other hand, when data is transmitted from the terminal 11 on the vehicle to the computer 1 or the network 10, the terminal 11 on the vehicle refers to the contents of the routing table to determine the power line carrier modem that transmits the data, and the corresponding power line. Data can be transmitted to the computer 1 or the network 10 by transmitting data to the carrier modem.

  In FIG. 1, the train 13 is approaching the connection point with the modem 1, and the S / N ratio between the modem 1 and the modem 3 tends to gradually increase. The power line carrying modems 4a and 4b installed on the ground. Even if the modem 1 and the modem 3 are selected to communicate with each other in steps 51 to 61 based on the positional relationship between the power line carrying modem 9 on the vehicle and the vehicle, the train 13 moves in the direction of the arrow shown in FIG. The position changes to the position shown in FIG. In this process, the SN ratio of the modem 3 and the modem 1 becomes the highest SN ratio at the connection point between the modem 1 and the overhead line 6, and the SN ratio gradually decreases after passing through the connection point.

  On the other hand, the SN ratio of the modem 3 and the modem 2 gradually increases as the connection point between the modem 2 and the overhead line 6 is approached. In this embodiment, since the SN ratio information is acquired at the set time in step 63, the SN ratio between the modem 2 and the modem 3 becomes higher than the SN ratio between the modem 1 and the modem 3, or Timing can be detected. For this reason, the combination suitable for the communication with the terminal 11 on the vehicle can be automatically switched from the communication between the modem 1 and the modem 3 to the communication between the modem 2 and the modem 3.

  If the communication is automatically switched between the modem 2 and the modem 3, the communication between the modem 1 and the modem 3 may not be completed, and transmission of necessary data may not be completed. As a countermeasure against such data loss, serial numbers are assigned to communication packets so that transmission can be continued from the upper layer. The serial number of the communication packet is managed to detect that the number is not a value indicating completion of transmission, and data loss is detected. When data loss is detected, the data is complemented by retransmission processing.

  By performing such processing, a modem that performs communication based on the SN ratio is selected even in a noisy environment. Therefore, communication can be performed using a communication modem having a high SN ratio, and high-speed communication can be performed. In addition, by installing multiple ground power line carrier modems in the station, even if the signal-to-noise ratio is reduced due to signal attenuation or inverter noise, it is possible to switch to a modem with a high signal-to-noise ratio and communicate. It is possible to transmit operation information and business support information that need to be transmitted at high speed.

  FIG. 4 is a flowchart illustrating another example of processing during communication. In the example shown in FIG. 2, the case where the power line carrier modem installed on the ground actively acquires the S / N ratio information is shown. However, in the example shown in FIG. The case of acquiring ratio information is shown.

  In step 71, the modem 3 transmits a training signal transmission request for calculating the S / N ratio to the modem 1. The modem 1 that has received the training signal transmission request transmits the training signal to the modem 3 in step 72. In step 73, the modem 3 receives the training signal and calculates the SN ratio. It records in the memory in preparation.

  In steps 74 to 76, the SN ratio for the model 2 is calculated in the same manner and recorded in the memory. In step 77, it is determined from the signal-to-noise ratio for modem 1 obtained in step 73 and the signal-to-noise ratio for modem 2 obtained in step 76. A routing table creation command or update command of the router 3 is transmitted through 1 or the modem 2.

  The router 3 that has received the routing table creation command or update command creates or updates the routing table in step 78.

  Step 78 and subsequent steps are the same as those in FIG. By processing in this way, the number of processing steps can be reduced as compared with the case shown in FIG. 2, so that the updating of the routing table can be completed in a short time. For this reason, the shortened time can be allocated to the data transmission time to increase the amount of communication data.

  In the above description, power line carrier modems 4a and 4b are installed on the ground, but three or more power modems may be installed, and the installation location of the modems is not limited to the station premises. It can also be installed in places such as cable terminals, cargo lines, and cargo terminals.

  In the communication between the ground and the train using the overhead line and the rail as the communication path, high-speed communication is possible even in a high noise environment by installing multiple power line carrier modems in the station premises, and communication is performed by selecting a modem with a high S / N ratio. Therefore, high-speed data communication becomes possible. In addition, even when another train enters the station while the vehicle is stopped, or when a device such as an inverter stops or operates, communication is possible without missing data by updating the routing table.

1 is a configuration diagram of a railway ground / train-to-train communication device according to an embodiment of the present invention. FIG. It is a flowchart which shows the process at the time of communication. It is a figure explaining the relationship with SN ratio when a train moves. It is a flowchart which shows the process at the time of communication.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Computer, 2 ... LAN cable, 3 ... Router, 4,9 ... Power line carrying modem, 5 ... Pantograph, 6 ... Overhead wire, 7 ... Rail, 8 ... Inverter, 10 ... Network, 11 ... Terminal on vehicle, 12 ... Wheel, 13 ... Train.

Claims (6)

  A plurality of first power line carrier modems installed in a station and installed in a router; and a second power line carrier modem connected to the first power line carrier modem via an overhead line and a rail and installed on a vehicle. Each of the plurality of first power line carrier modems and each of the second power line carrier modems to transmit and receive training signals, thereby providing information on the SN ratio between the first power line carrier modem and the second power line carrier modem. The first power line carrier modem having a high S / N ratio is selected from the calculated S / N ratio information, and communication between the router and the second power line carrier modem is performed via the selected power line carrier modem. Railway ground and inter-train communication equipment.   A plurality of first power line carrier modems installed on the ground, a router connected to the plurality of first power line carrier modems, a computer or network connected to the router, and a second one installed on the vehicle A power line carrying modem, a terminal connected to the second power line carrying modem, an overhead line and rails connected to the first power line carrying modem and the second power line carrying modem, Information on the S / N ratio between the first power line carrier modem and the second power line carrier modem is calculated by transmitting and receiving a training signal between each of the one power line carrier modem and the second power line carrier modem. The first power line carrier modem having a high S / N ratio is selected from the S / N ratio information, and communication between the computer or network and the terminal is performed via the selected power line carrier modem. Cormorant railway ground-train between the communication devices.   The rail-ground / train-to-train communication apparatus according to claim 1 or 2, wherein the first and second power line carrier modems communicate by an OFDM communication system or a direct spread spectrum communication system.   The train ground-to-train communication apparatus according to claim 1 or 2, wherein the transmission and reception of the training data is executed when a set time interval or a communication error exceeds a set number of times.   The router is configured to issue an instruction for obtaining an S / N ratio between the first power line carrier modem and the second power line carrier modem to the first power line carrier modem or the second power line carrier modem, and the calculation The railway ground / train-to-train communication device according to claim 1, wherein the routing table is created or updated based on the SN ratio. A communication method for communicating with an overhead line and a rail as a communication path, which is installed in a station and connected to each of a plurality of first power line carrier modems installed in a router via an overhead line and a rail. Information on the SN ratio between the first power line carrier modem and the second power line carrier modem is calculated by transmitting and receiving a training signal to and from the second power line carrier modem, and a high SN ratio is obtained from the calculated SN ratio information. A rail-ground / train-to-train communication method of selecting a first power line carrier modem of a ratio and performing communication between the router and the second power line carrier modem via the selected power line carrier modem.

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