JPH0369456B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a train radio communication system, and in particular, the radio direction from a ground station to a mobile station of each train is in a broadcast mode with an address attached, so that there is no specific area. The radio direction from the mobile station to the ground station accessing the train concerns a system that accesses the radio channel and performs packet transmission in transmission contention mode.

[Prior Art] Conventionally, as a packet data transmission system using train radio, for example, Chapter 4 (Electronic Control Communication System for Shinkansen) published by the Institute of Electronics and Communication Engineers on December 10, 1981 communication system, no.
As shown on pages 133-144, the start of data communication is discussed over the phone, and the wireless line to be accessed is set up by polling via the fixed data line, which is the connection control line. There is now a channel access method based on physical switching.

Normally, data communication lines for train radio are classified into two types depending on their use: fixed data lines that periodically collect short fixed data, and general-purpose data lines that transmit relatively long data that occurs randomly. Communication connection control for fixed data systems is performed by polling mobile stations, and connection control for general data systems is performed via fixed data lines.

FIGS. 4 and 5 are shown in the above-mentioned document, and respectively show the configuration of a general-purpose data system and an example of a terminal device transmission control sequence in a conventional train wireless communication system.

In FIG. 4, a data terminal device can be connected to a central station 1, a control station 2, and a mobile station 4, respectively, and a total of four wireless channels can be assigned, including channels ch17 and ch18 shown. There is. One central station 1 is placed in each system, and several control stations 2 that supervise about 10 base stations 3 are placed along the route and are supervised by the central station 1. Central station 1, control station 2, and base station 3
are connected by a fixed dedicated data line (wired), and between the base station 3 and mobile station 4,
Connected by LCX (Leaky Coaxial) wireless line. The central station 1, the control station 2, and the base station 3 constitute a terrestrial (fixed) station, and the mobile station 4 is also called an on-vehicle station.

What is shown in the central station 1 and the control station 2 are grid-shaped line switches as data transmission racks 1a and 2a, respectively, which connect designated central stations according to connection control information via fixed data lines. A radio channel used by the central station terminal device Tg of station 1 or the ground terminal device (not shown) of control station 2 and the mobile station terminal device (not shown) with which it communicates.
It connects to a land line that supports ch17 and ch18.

Next, using the general-purpose data system shown in Figure 4 as an example, the vehicle monitor, that is, the operating status of the train and the operating status of each vehicle's equipment will be displayed on the display in the driver's cab as shown in Figure 5, and the driver's judgment and The transmission control sequence of the mobile station terminal device that supports the treatment will be explained. During transmission, the vehicle driver, while in telephone contact with the train dispatcher, sends a "transmission request" signal to the data transmission frame of the mobile station 4 through key operations (CTC key presses) on the mobile station side terminal device using the vehicle monitor. Sent to 4a.

The data transmission rack 4a of the mobile station 4 outputs a "connection request" signal (the thick arrow indicating this signal represents a fixed data line) as a response to the fixed data type polling request. Upon receiving this, the data transmission rack 1a of the central station 1 outputs a "reception request" signal to the terminal device Tg on the central station 1 side, such as a command display, and then outputs a "reception OK" signal from the terminal device Tg. After confirming the input of the signal, a "connection OK" signal with an address is sent to the mobile stations 4 all at once via the fixed data line. The data transmission rack 4a of the mobile station 4 of the address concerned receives this,
Sends a “send ready” signal to the mobile station terminal device.

The above sequence completes the line setting between the mobile station terminal device and the central station terminal device Tg, and from now on, screen data and
An "ACK" signal is mutually transferred as shown.

When the necessary data transfer between both terminal devices is completed, the next line release sequence begins. The line release sequence is the same as the line setting above.
By pressing the clear key on the mobile station terminal device, an "EOT (end of text)" signal is sent to the mobile station 4, and the data transmission rack 4a of the mobile station 4 sends a "release request" signal as a response to the polling request for the fixed data line. is output to the central station 1, and the data transmission rack 1a of the central station 1 that receives this sends a "release" signal with an address all at once via the regular data line, thereby completing the line release sequence.

This completes the data transmission between the terminal devices, that is, between the vehicle monitor and the command display.

[Problems to be solved by the invention] Since the conventional system is configured as described above, there is no problem when collecting data periodically or when transmitting long data between the same terminal devices, but when the system is mobile In order to apply it to a so-called packet transmission system that sends and receives small amounts of data that occur randomly in time, such as communication between multiple data terminal devices of stations and ground stations, (1) (2) It is not possible to quickly control the contention for the transmission rights of wireless channels.

The present invention has been made in order to solve the above-mentioned problems, and provides a packet transmission line access system that can control the transfer of transmission rights of radio channels in train radio at high speed and switch them randomly at high frequency. The purpose is to obtain.

[Means for Solving the Problems] In order to achieve the above object, the train wireless communication system according to the present invention includes a method for accessing a packet transmission path from an on-board mobile station to a ground station.
The ground station separates a regular data line that is a connection control line and a general-purpose data line that is a data line, and includes means for detecting the presence or absence of a carrier for each radio channel, and transmitting the detected results in the first radio direction. means for simultaneously notifying the mobile stations as each wireless channel busy information at a polling cycle via a fixed data line, and the mobile station selects a wireless channel that is not busy based on the channel busy information when there is a transmission request. The packet data is transmitted in the second radio direction via a general-purpose data circuit.

[Operation] The transmission right contention control in the direction from the mobile station to the ground station in the train radio communication system of the present invention uses a connection control line separate from the data line to check the presence or absence of a carrier of a radio channel detected at the ground station. The busy information is repeated at short intervals and notified all at once in broadcast mode, allowing the mobile station to know free channels without delay, and enabling random and high-speed switching of transmission path access from the mobile station to the ground station. There is.

[Embodiment] An embodiment of the train wireless communication system according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically showing the train wireless communication system of the present invention. In addition to the conventional example shown in FIG. 4, FIG. A circuit 3a detects the presence or absence of the detected carrier and informs the central station 1 of the mobile station 4.
A circuit 1b for transmitting data to is provided.

In the transmission control sequences shown in FIGS. 2a and 2b, a general-purpose data line, which is a data line, and a regular data line, which is a connection control line, are shown separately. In the fixed data line, the presence or absence of the carrier of the general-purpose data line is determined every boring period t in the broadcast mode from the ground to the top of the vehicle according to the output of the carrier transmission circuit 1b of the general-purpose data line provided in the central station 1 and base station 3. is being transmitted repeatedly.

On the other hand, in a general-purpose data line, when a "transmission request" signal is generated from a mobile station terminal device (not shown), a wireless channel that is not busy is used based on channel busy information that is periodically notified on a fixed data line. from the mobile station 4 to the ground station (central station 1,
A packet is sent in a direction (consisting of a control station 2 and a base station 3). At this time, since the ground station monitors the presence or absence of a carrier on the general-purpose data line, it can notify all at once whether or not there is a carrier on that radio channel in a short period.

Figure 2a shows the case where there are no packets sent to the same radio channel at the same time, that is, there is no collision, and the ground station receives the packets correctly and immediately sends an ACK (acknowledgement) signal. At the same time, the ground station terminal device (central station 1 terminal device Tg,
Data is output to a terminal device (not shown) of the control station 2.

On the other hand, FIG. 2b shows that when the first packet is sent,
This shows a case where a packet is sent from the mobile station 4 of another train using the same radio channel, that is, a transmission collision occurs, and the packet is not correctly received by the ground station. In this case, the mobile station does not receive a response from the ground station even after waiting for a predetermined period of time, so it retransmits the same packet after the timeout period has elapsed. The figure shows a case where, during retransmission, no transmission collision occurred and the data was correctly received, so an "ACK" signal was returned and the data was output to the ground station terminal device.

Note that the carrier is detected on the ground station side, not on the mobile station, because when it is detected on the mobile station side, the mobile station side detects the carrier →
This is because all trains are required to have a receiving function for all radio channels toward the ground station.

FIG. 3 shows a time chart for supplementary explanation of the above transmission control sequence. In the fixed data line, the wireless channel busy information of the general data line is transmitted from the ground station to the mobile station at regular intervals as shown in Figure 3a, and all trains within the relevant cut area can receive this information. From there, each train detects and uses a non-busy radio channel to transmit packet data in response to a "request to transmit" signal. In Figures 3b and 3c, since no carrier is detected in the wireless channel busy information shown in Figure 3a, trains 1 and 2 are connected after confirming ``wireless channel f ₁ ready''. A case is shown in which both packets are sent using channel number _f1 , a transmission collision occurs, and the packets are retransmitted after a timeout. In this case, as shown in the channel busy information in FIG. 3a, "f ₁ busy" is notified from the ground station to the mobile stations all at once in broadcast mode. Furthermore, Fig. 3 d shows a case where train 3, which has confirmed "f ₂ ready" in the channel busy information of Fig. 3 a, sends out continuous packets corresponding to long data using radio channel f ₂ . has been done. In this case, " _f2 busy" is notified all at once in the broadcast mode toward the mobile stations, like the channel busy information in FIG. 3a.

In the above embodiment, the mobile stations of each train arbitrarily use a wireless channel that is not busy in response to channel busy information that is notified all at once in broadcast mode via a fixed data line. By specifying a wireless channel for each train using a fixed data line, it is possible to prevent transmission collisions from concentrating on a specific channel, and also to prevent transmission collisions from concentrating on a specific channel. can be accessed without collision.

[Effects of the Invention] As described above, according to the present invention, in response to the output of the carrier detection circuit provided at the ground station, Since the busy information of the data circuits is notified all at once in short cycles, there is an effect that the wireless channel can be accessed at high speed, frequently, and randomly.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the train wireless communication system according to the present invention, FIGS. 2 a and b are diagrams explaining the transmission control sequence of the system of the present invention shown in FIG. 1, and FIG. 2 is a time chart supplementary explanation of the sequence in FIG. 2, FIG. 4 is a configuration diagram of a general-purpose data system in a conventional train radio communication system, and FIG. 5 is a diagram explaining a transmission control sequence in a conventional train radio communication system. It is. 1: Central station, 1b: Transmission circuit, 2: Control station,
3: base station, 3a: detection circuit, 4: mobile station,
Tg: Terminal device. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. The first radio direction from the ground station to the mobile station of each train is accessed in broadcast mode with an added address,
In a train radio communication system in which a second radio direction from the mobile station to the ground station accesses a radio channel in a transmission right contention mode, the ground station includes: means for detecting the presence or absence of a carrier for each of the radio channels; means for simultaneously notifying the mobile stations of the detected results as each wireless channel busy information in the first wireless direction via a fixed data line at a polling cycle, and the mobile station connects the channels when there is a transmission request. A train radio communication system characterized in that packet data is transmitted in the second radio direction via a general-purpose data line using a non-busy radio channel based on busy information. 2. The train wireless communication system according to claim 1, wherein the ground station includes a central station, a control station, and a base station. 3. The train wireless communication system according to claim 1 or 2, wherein the wireless channel is specified for each train in advance by the fixed data line.