JP7565556B2 - Mobile wireless communication system - Google Patents

Description

The present invention relates to a mobile wireless communication system in which a moving vehicle communicates wirelessly with an external terrestrial wireless station.

Mobile wireless communication systems have been proposed in the past, in which moving objects such as trains and vehicles communicate wirelessly with external terrestrial wireless stations (see, for example, Non-Patent Document 1).

In this mobile wireless communication system, for example when the mobile body is a train, ground wireless stations are dotted in advance along the tracks along which the train runs. Then, the ground wireless stations distribute transmission information to the train running on the tracks via wireless communication, or transmit transmission information sent from the running train via wireless communication. This makes it possible to send necessary information to the driver who operates the train and the conductor who is in charge of the train via the transmission information from the ground wireless stations, and also makes it possible to transmit information about various events and happenings that occur on the train to the ground wireless stations via this transmission information.

In particular, millimeter wave bands are often used for wireless communication between ground radio stations and trains. Millimeter wave bands have a strong tendency to travel in a straight line, making them suitable for railways with long, linear service areas. They also have the advantage of having a wide usable frequency range and the ability to transmit large amounts of information in a short period of time. For this reason, by utilizing wireless communication in the millimeter wave band, it is possible to transmit large amounts of information required for train control and vehicle status monitoring, while also securing large amounts of communication resources and providing comprehensive information to passengers.

Yukiya Tateishi, Tetsunori Hattori, Kunihiro Kawasaki, "Millimeter Wave Communications in Railways", IEICE Technical Report, MWP2013-48, pp.7-12, Nov. 2013

When implementing the above-mentioned mobile wireless communication system, if the train only has one antenna, the train may move away from the ground wireless station before all the transmitted information is received, especially in a short-range wireless communication method such as the millimeter wave band. For this reason, in order to stably transmit and receive transmitted information by wireless communication, it is necessary to provide antennas at multiple different locations in the direction of travel, and to receive the transmitted information that cannot be received by the antenna at the front in the direction of travel at an antenna at the rear in the direction of travel. However, no technology that can achieve this has yet been proposed.

The present invention was devised in consideration of the above-mentioned problems, and its purpose is to provide a mobile wireless communication system in which a moving vehicle communicates wirelessly with an external terrestrial wireless station while moving, taking into consideration the case where the train moves away from the terrestrial wireless station before receiving all the transmitted information under a short-range wireless communication method such as the millimeter wave band, by providing antennas at multiple different locations in the direction of travel, and receiving the transmitted information that cannot be received by the antenna at the front in the direction of travel at an antenna at the rear in the direction of travel, thereby realizing stable mobile wireless communication without omissions.

To solve the above-mentioned problems, the inventors have invented a mobile wireless communication system in which a moving vehicle communicates wirelessly with an external terrestrial wireless station by arranging two or more antennas on the moving vehicle facing in the direction of travel, and selecting an antenna for transmitting and receiving transmission information to and from a terminal device based on the current traveling position and the position of the terrestrial wireless station.

A mobile radio communication system according to a first aspect of the present invention is a mobile radio communication system in which a moving body communicates wirelessly with an external terrestrial radio station, the moving body comprising: antennas arranged at two or more different positions in a traveling direction for wirelessly communicating transmission information with the terrestrial radio station; a terminal device for respectively transmitting and receiving the transmission information to and from the antennas; a traveling position acquisition means for acquiring a current traveling position; and a selection means for selecting an antenna for transmitting and receiving the transmission information to and from the terminal device based on the current traveling position acquired by the traveling position acquisition means and the position of the terrestrial radio station, the terrestrial radio stations being arranged at two or more positions in a traveling direction, the selection means selecting an antenna for transmitting and receiving the transmission information to and from the terminal device for each of the ground radio stations based on the position of each antenna corresponding to the current traveling position acquired by the traveling position acquisition means and the position of each of the ground radio stations, and determining whether or not to transmit transmission information from a second terrestrial radio station located on the other side of the traveling direction to the terminal device based on the transmission information received from a first terrestrial radio station located on one side of the traveling direction .

A second aspect of the present invention provides a mobile wireless communication system according to the first aspect of the present invention, wherein the selection means acquires a position of each of the antennas corresponding to a current traveling position acquired by the traveling position acquisition means a plurality of times, calculates a calculated position S from the acquired positions of each antenna ( _x1 , _x2 , ..., _xn ) based on the following formula (1) or (2), and selects an antenna for transmitting/receiving the transmission information to/from the terminal device based on the calculated position S and the position of the terrestrial wireless station: S = _a1 x _x1 + _a2 x _x2 + ... + _{an xn} (1)
S=a ₁ ×x ₁ ×a ₂ ×x ₂ ×...×a _n x _n (2)
(a ₁ to a _n are predetermined coefficients, and n is the number of times the antenna position is acquired)
It is characterized by:

The mobile radio communication system according to the third invention is the first or second invention, characterized in that the terminal device combines the transmission information received via one of the antennas and the transmission information received via the other antennas to form one transmission information.

The mobile wireless communication system according to the fourth invention is any one of the first to third inventions, characterized in that the mobile body is a train that runs on a railroad track, and the ground wireless station is provided on the roadside of the railroad track and performs millimeter wave band wireless communication with the mobile body.

According to the present invention having the above-mentioned configuration, when the data sent from the terrestrial radio station is large, such as in-car advertising information or various video contents, it may be the case that not all of the transmitted information can be received by the antenna located at the front in the traveling direction, even in wireless communication using the millimeter wave band. This is particularly likely to occur when the moving body is moving at a particularly fast speed, such as a Shinkansen. In such a case, the remaining transmitted information can be received from the terrestrial radio station by the antenna located at the rear in the traveling direction. Such a processing operation can be realized by selecting an antenna by the selection unit based on the positional relationship of each antenna to the position of the terrestrial radio station. As a result, the transmitted information that cannot be received by the antenna at the front in the traveling direction is received by the antenna at the rear in the traveling direction, making it possible to realize stable mobile wireless communication without omissions.

FIG. 1 is a schematic diagram showing the entire mobile radio communication system to which the present invention is applied. FIG. 2 is a block diagram showing the internal configuration of a moving object. FIG. 3 is a diagram for explaining the operation of the mobile radio communication system to which the present invention is applied. FIG. 4 is another diagram for explaining the operation of the mobile radio communication system to which the present invention is applied. FIG. 5 is a diagram showing an example of a simulation in the case of transmitting terrestrial radio station data.

Below, a mobile wireless communication system to which the present invention is applied will be described in detail with reference to the drawings.

Figure 1 is an overall schematic diagram of a mobile wireless communication system 1 to which the present invention is applied. The mobile wireless communication system 1 includes a mobile body 2 traveling in a traveling direction A, a plurality of ground wireless stations 3 scattered along the traveling direction of the mobile body, and a central control station 4 capable of communicating with each of the ground wireless stations 3 by wire or wirelessly.

In the following explanation, the mobile object 2 will be described taking as an example a train running on a track 5, but is not limited to this and includes all types of mobile objects such as monorails, cars, buses, trucks, motorcycles, airplanes, etc. The mobile object 2 has one or more terminal devices 6 set inside.

Assuming that the mobile object 2 is a train, the ground wireless station 3 is a fixed base station located on the shoulder of the track 5 on which the train runs. The ground wireless station 3 transmits transmission information to the moving mobile object 2 by wireless communication. The ground wireless station 3 also receives transmission information from the moving mobile object 2 by wireless communication. The ground wireless station 3 may use a millimeter wave band for wireless communication with the mobile object 2. By using the millimeter wave band for this wireless communication, a large amount of information can be transmitted in a short time, and it is necessary to transmit a large amount of information to control the train or monitor the state of the vehicle, and it is possible to secure a large amount of communication resources and provide a wide range of information by the terminal device 6 installed in the mobile object 2. The ground wireless station 3 may form a small service area called a microcell, and each of them may transmit content specific to the service area as transmission information to the mobile object 2.

The central control station 4 is a server that receives and stores information transmitted from the terrestrial radio stations 3. Information is sent from a large number of mobile objects 2 to the terrestrial radio stations 3, which then transmit the information to the central control station 4. This allows the central control station 4 to centralize the information acquired by each mobile object 2. By centralizing such information, the central control station 4 can compile information acquired by the mobile objects 2 that indicates more detailed conditions in each region and time period into a single database, making it possible to utilize the information for a variety of purposes.

The central control station 4 also transmits to the terrestrial radio station 3 the content and information to be distributed to the mobile object 2. This allows the terrestrial radio station 3 to convert the information transmitted from the central control station 4 into transmission information and distribute it to the mobile object 2 via wireless communication. In particular, disaster information from various locations and information with a high degree of real-timeness can be acquired or generated collectively by the central control station 4, and the information can be arranged for each location of the terrestrial radio station 3 as necessary, which can increase the convenience of distribution.

Next, we will explain the detailed configuration of the moving body 2. Figure 2 shows the block configuration inside the moving body 2.

The mobile body 2 is equipped with a plurality of antennas 20a, 20b, a terminal device 6 capable of transmitting and receiving information to and from the antennas 20, a selection unit 24 that selects the antennas 20a, 20b that transmit and receive transmission information to and from the terminal device 6, a traveling position acquisition unit 23 connected to the selection unit 24, and a driving control unit 21 that controls the driving of the mobile body 2 itself.

The terminal devices 6 are electronic devices that are pre-installed inside the moving body 2 at different positions facing the traveling direction A, and are configured, for example, as a smartphone, tablet terminal, PC, display terminal, or other device that displays information to passengers or crew members or has a user interface for inputting commands, but are not limited to these. The terminal devices 6 may be configured as various electronic devices, devices, sensors, etc. that are not provided with a user interface. The terminal devices 6 are not limited to those pre-installed inside the moving body 2, and may be configured as mobile terminals that passengers or crew members carry. Examples of such mobile terminals include smartphones, tablet terminals, notebook PCs, and wearable terminals.

The driving control unit 21 includes all components for controlling the driving of the moving body 2, and is composed of a steering wheel, accelerator, brakes, gears, etc., and the driving operations performed by the driver are reflected in the movement of the moving body 2. Of course, this driving control unit 21 may also be equipped with automatic steering and automatic driving functions.

The running position acquisition unit 23 acquires the current running position of the moving body 2 that has been moved by the driving control unit 21. The running position to be acquired may be set by the system side each time, as to which position of the moving body 2 that is long in the running direction A should be, or at least one position, such as the front or rear end of the moving body 2, or the front of the second car from the front, must be set in advance. The running position acquisition unit 23 may acquire the running position of the moving body 2, for example, by using a GPS (Global Positioning System), may acquire it through a beacon, or may acquire it by positioning using radio waves from a ground wireless station 3 as a carrier base station. The running position acquisition unit 23 may continuously acquire the current running position. The time interval for acquiring the running position may be any time interval, such as seconds, milliseconds, microseconds, nanoseconds, picoseconds, etc. The running position acquisition unit 23 transmits the current running position of the moving body 2 acquired in this way to the selection unit 24 each time it acquires it.

The antenna 20 is disposed at two or more different positions in the direction of travel. In the example of FIG. 2, an example is shown in which an antenna 20a is disposed on the front side in the direction of travel, and an antenna 20b is disposed on the rear side in the direction of travel. The antenna 20 receives a radio signal including transmission information in the millimeter wave band from the ground radio station 3 and converts it into an electrical signal. The antenna 20 distributes the transmission information converted into an electrical signal to each terminal device 6. The antenna 20 also converts the transmission information consisting of an electrical signal transmitted from the terminal device 6 into a radio signal and transmits it to the ground radio station 3.

Incidentally, it is assumed that the position information regarding the position of each antenna 20 in the traveling direction A is known and that all of this information is stored in the selection unit 24.

The selection unit 24 selects, from among the antennas 20a and 20b, the antenna 20 to be used for transmission and reception between the terrestrial radio station 3 and the terminal device 6. As a method for selecting the antenna 20 to transmit the transmission information, the connection circuits that connect the terminal device 6 to the antennas 20a and 20b may be switched on or off, or the selection unit 24 may receive the transmission information to be transmitted once and control whether to distribute it again to the terminal device 6 selected by the selection unit 24 itself or not to distribute it to the terminal device 6.

When transmitting transmission information generated in the terminal device 6 to the terrestrial radio station 3 via the antenna 20, the selection unit 24 also selects the antenna 20 that will wirelessly communicate with the terrestrial radio station 3. As a method for selecting the antenna 20 that will wirelessly communicate the transmission information, the connection circuits that connect the terminal device 6 and the antenna 20 may be switched on or off, or the selection unit 24 may receive the transmission information transmitted from the terminal device 6 once and transmit it only to the antennas 20a, 20b selected by the selection unit 24 itself. When the transmission information is transmitted from the terminal device 6 via short-range wireless communication, the selection unit 24 may control this to select the antennas 20a, 20b that will transmit the transmission information.

The selection unit 24 also stores the positions of each ground radio station 3 in the traveling direction A. The current traveling position of the mobile unit 2 acquired by the traveling position acquisition unit 23 is sent to the selection unit 24. The selection unit 24 stores all of the position information related to the positions of the antennas 20a and 20b in the traveling direction A, which are already known to the selection unit 24. Based on the current traveling position of the mobile unit 2 acquired by the traveling position acquisition unit 23, the positions of the antennas 20a and 20b in the traveling direction A, and the position of the ground radio station 3, the selection unit 24 selects an antenna 20 that transmits and receives transmission information to and from the terminal device 6. The operation of the selection unit 24 will be described in detail below.

Figures 3(a) and 3(b) illustrate the operation of the mobile wireless communication system 1 to which the present invention is applied by extracting and illustrating only the positional relationship between the terminal device 6 in the mobile unit 2, the antennas 20a and 20b, and the terrestrial wireless station 3.

The moving body 2 approaches a certain terrestrial radio station 3 while traveling in a traveling direction A. When transmitting information from this terrestrial radio station 3 to the terminal device 6 via the antennas 20a and 20b, the selection unit 24 grasps the current traveling position of the moving body 2 acquired by the traveling position acquisition unit 23. If the actual traveling position of the moving body 2 on the map can be acquired, the position information within the moving body 2 at the antennas 20a and 20b has already been acquired and is known, so the actual position on the map in the traveling direction A at the antennas 20a and 20b can be acquired.

The selection unit 24 is also premised on storing the actual map positions of each ground radio station 3 in the traveling direction A. Therefore, the selection unit 24 can grasp the positional relationship between the actual map positions of the antennas 20a, 20b in the traveling direction A and the actual map positions of the ground radio station 3 in the traveling direction A. Then, the positional relationship between the antennas 20a, 20b and the traveling direction A of the ground radio station 3 can be grasped every time the traveling position acquisition unit 23 detects the position of the mobile unit 2. By continuously acquiring the current position detection of the mobile unit 2 by the traveling position acquisition unit 23 in chronological order, it becomes possible to continuously grasp the positional relationship between the antennas 20a, 20b and the traveling direction A of the ground radio station 3 in chronological order.

When the positional relationship grasped continuously in time series shows that antenna 20a is closest to terrestrial radio station 3, as shown in FIG. 3(a), for example, the selection unit 24 selects only antenna 20a and does not select other antennas 20b. When the positional relationship grasped continuously in time series shows that antenna 20b is closest to terrestrial radio station 3, as shown in FIG. 3(b), for example, the selection unit 24 selects only antenna 20b and does not select other antennas 20a as a distribution destination.

In other words, as the mobile unit 2 moves in the travel direction A, the antenna 20 closest to the terrestrial radio station 3 also changes from antenna 20a to antenna 20b. As the antenna 20 closest to the terrestrial radio station 3 changes from antenna 20a to antenna 20b, the selection of the antenna 20 that will receive the transmission information sent from the terrestrial radio station 3 is switched. In other words, by controlling the reception of transmission information via the antenna 20 closest to the terrestrial radio station 3 and not receiving transmission information via the antenna 20 that is not close, the present invention achieves the excellent effects described below.

For example, when the data sent from the terrestrial radio station 3 is large-volume data such as in-car advertising information or various video contents, it may not be possible to receive all of the transmitted information using only the antenna 20a located at the front in the traveling direction A, even with wireless communication in the millimeter wave band. This may occur especially when the moving body 2 is moving at a particularly high speed, such as a Shinkansen. In such a case, the remaining transmitted information is received from the terrestrial radio station 3 by the antenna 20b located at the rear in the traveling direction A. Such processing operations can be realized by selecting an antenna 20 using the selection unit 24 based on the positional relationship of each antenna 20a, 20b to the position of the terrestrial radio station 3.

In other words, according to the present invention, the transmission information received by antenna 20a located on the forward side of the traveling direction A and the transmission information received by antenna 20b located on the rear side of the traveling direction A may be combined with each other on the terminal device 6 side to form a single transmission information.

The transmission information received by antennas 20a and 20b is sent to terminal device 6, but the terminal device 6 may combine the transmission information sent from antennas 20a and 20b, or may manage and use the information as separate data.

In the above explanation, an example was given in which the antenna 20 consists of two antennas 20a and 20b, but this is not limited to this, and the same applies to cases in which there are three or more antennas 20. As the antenna 20 closest to the terrestrial radio station 3 changes, the selection of the antenna 20 that will receive the transmission information sent from the terrestrial radio station 3 is switched.

In addition, according to the present invention, any antenna 20 may be selected as long as it is based on the position of each antenna 20 that can be grasped via the current traveling position of the mobile unit 2 and the position of the terrestrial radio station 3, and is not limited to the above-mentioned embodiment.

In addition, according to the present invention, the detection of the traveling position of the mobile body 2 may be continuously acquired, and the antenna 20 may be selected and switched based on the multiple traveling positions acquired continuously.

In this case, if multiple travel positions are acquired over a certain period of time, the position information of each antenna 20a, 20b in the mobile unit 2 corresponding to each travel position can also be acquired. If two travel positions are acquired within a predetermined period of time, the position information P1, P2 of each antenna 20a, 20b corresponding to each travel position can be acquired. The acquired position information P1, P2 of each antenna 20a, 20b is calculated based on an arithmetic formula. This is performed not only for one antenna 20a, but also for the other antenna 20b in the same manner. Then, based on the calculation result of the position information of each antenna 20 and the positional relationship with the terrestrial radio station 3, the antenna 20 that transmits and receives transmission information to and from the terrestrial radio station 6 may be selected. This arithmetic formula may be any conventional arithmetic formula, but it may be simplified and the position obtained by averaging the position information P1, P2 of each antenna 20 may be output as the calculation result. In addition to averaging the position information, the calculation formula may be configured as a formula that uses only the first or last acquired position information, or may be configured as a calculation formula that sets a desired weighting on either the position information P1 or P2. Furthermore, if three or more driving positions are acquired within a specified period, three or more pieces of position information for each antenna 20 can be acquired in the same way. In such a case, the three or more pieces of position information may be introduced into the calculation formula, and the position of each antenna 20 may be determined based on the calculation results.

The position of each antenna 20 according to the acquired current traveling position may be acquired multiple times, and a calculated position S may be calculated based on the acquired positions ( _x1 , _x2 , ..., _xn ) of each antenna 20 based on equation (1) or (2). Then, an antenna 20 for transmitting and receiving transmission information to and from the terminal device 6 may be selected based on the calculated position S and the position of the terrestrial radio station 3.
S=a ₁ ×x ₁ +a ₂ ×x ₂ +...+a _n x _n (1)
(a ₁ to a _n are predetermined coefficients, and n is the number of times the antenna position is acquired)

Then, based on the calculated position S and the position of the terrestrial radio station 3, an antenna 20 is selected to transmit and receive transmission information to and from the terminal device 6.

For example, when the position of each antenna 20 is acquired twice per unit time, the above formula (1) is expressed as S = _a1 x _x1 + _a2 x _x2 . If the average of the positions _x1 and _x2 of each antenna 20 is to be calculated, both _a1 and _a2 will be 1/2, in other words, 1/n. If either one of the positions _x1 and _x2 of each antenna 20 is adopted, either one of _a1 or _a2 will be 0. Furthermore, if the positions _x1 and _x2 of the antenna 20 are to be weighted as desired, the weights can be preset for _a1 and _a2 , respectively.

Here, by determining a ₁ to a _n in advance on the system side or on the user side, it is possible to obtain the calculated position S of the antenna 20 for each vehicle under a unified operation.

In the present invention, the calculation of the calculated position S is not limited to the above-mentioned embodiment, but may be based on the following formula (2).

S=a ₁ ×x ₁ ×a ₂ ×x ₂ ×...×a _n x _n (2)
Similarly, the calculated position S can be obtained by using (2).

4(a) and (b) show an example of receiving transmission information from a plurality of terrestrial radio stations 3. In the example of FIG. 4, a first terrestrial radio station 3a located in the front side of the traveling direction A and a second terrestrial radio station 3b located in the rear side of the traveling direction A transmit different transmission information. When the antenna 20a is closest to the terrestrial radio station 3a as shown in FIG. 4(a), the selection unit 24 selects only the antenna 20a and does not select the other antennas 20b. As a result, the transmission information from the terrestrial radio station 3a is sent to the terminal device 6 via the antenna 20a. When the antenna 20b is closest to the terrestrial radio station 3b as shown in FIG. 4(b), the selection unit 24 selects only the antenna 20b and does not select the other antennas 20a. As a result, the transmission information from the terrestrial radio station 3b is sent to the terminal device 6 via the antenna 20b.

In the above example, as the mobile unit 2 moves in the travel direction A and the antenna 20 closest to the terrestrial radio station 3 changes from antenna 20a to antenna 20b, the mobile unit 2 receives transmission information from the terrestrial radio station 3a in front via antenna 20a, and from the terrestrial radio station 3b in the rear via antenna 20b, but this is not limited to this, and the allocation of antennas 20a, 20b to receive transmission information from each of the terrestrial radio stations 3a, 3b may be configured in any combination.

In the above explanation, the antenna 20 is composed of two antennas 20a and 20b, and two terrestrial radio stations 3a and 3b, but the present invention is not limited to this. The same applies when there are three or more antennas 20 or terrestrial radio stations 3, and as the antenna 20 closest to the terrestrial radio station 3 changes, the selection of the antenna 20 that will receive the transmission information sent from the terrestrial radio station 3 is switched, and an antenna 20 that will receive the transmission information from the terrestrial radio station 3 is assigned.

The transmission information sent from the terrestrial radio stations 3a and 3b may be different from each other. For example, consider a case where desired content is superimposed on the transmission information and sent from the terrestrial radio station 3 to the passenger via the terminal device 6. In this case, the transmission information sent from the terrestrial radio station 3a includes basic information for explaining the basic outline of the content, and the transmission information sent from the terrestrial radio station 3b includes the actual data of the content.

In such a case, the mobile unit 2 first receives transmission information from the terrestrial radio station 3a via the antenna 20a, and judges whether the content should be distributed to the terminal device 6 by looking at the basic information contained in the transmission information. This judgment may be made by the selection unit 24 or the terminal device 6. As a result, if it is judged that the actual data of the content should be distributed, the selection unit 24 controls the mobile unit 24 to receive transmission information containing the actual data from the terrestrial radio station 3b via the antenna 20b and transmit this to the terminal device 6. On the other hand, if it is judged that the actual data of the content should not be distributed, even if the transmission information containing the actual data is received from the terrestrial radio station 3b via the antenna 20b, the selection unit 24 controls the mobile unit 24 to discard the data without transmitting it to the terminal device 6. At this time, the mobile unit 2 may be set not to receive transmission information via the antenna 20b instead of discarding the data.

In this way, according to the present invention, it may be possible to determine whether or not to transmit to the terminal device 6 transmission information from the terrestrial radio station 3b located behind the vehicle in the traveling direction A, based on the transmission information received from the terrestrial radio station 3a located ahead in the traveling direction A. This makes it possible to prevent a decrease in reception efficiency by preventing unnecessary transmission information from being received.

In such a case, conversely, based on the transmission information received from the terrestrial radio station 3b located on the rear side in the traveling direction A, it may be determined whether or not to transmit the transmission information from the terrestrial radio station 3a located on the front side in the traveling direction A to the terminal device 6. In other words, based on the transmission information received from the terrestrial radio station 3 located on one side in the traveling direction A, it may be determined whether or not to transmit the transmission information from the terrestrial radio station 3 located on the other side in the traveling direction A to the terminal device 6.

In addition, according to the present invention, the relative positional relationship between the position of the antenna 20 and the position of the terrestrial radio station 3 may be acquired in advance. The relative positional relationship here is not limited to the case where the position of the antenna 20 and the position of the terrestrial radio station 3 are substantially the same in the A direction, but may be diagonal to each other. For example, as shown in FIG. 3(a), the relative positional relationship between the antenna 20b and the terrestrial radio station 3 is diagonal. Such a relative positional relationship may be diagonal to each other, or may be substantially the same in the A direction as the relative positional relationship between the antenna 20a and the terrestrial radio station 3 shown in FIG. 3(a). The relative positional relationship may be defined by the relationship between the position coordinates of the position of the antenna 20 and the position of the terrestrial radio station 3, the angle of the line segment connecting these position coordinates, etc.

Such relative positional relationships are acquired in advance, and when actually selecting an antenna 20, the acquired relative positional relationship is referenced. Then, when the position of one antenna 20 according to the newly acquired current traveling position almost satisfies the referenced relative positional relationship with the position of the terrestrial radio station 3, that one terminal device may be selected.

In the above example, the case of selecting an antenna 20 that receives transmission information from a terrestrial radio station 3 has been described as an example, but the present invention is not limited to this. Conversely, the same applies to the case of selecting an antenna 20 to transmit transmission information to a terrestrial radio station 3 via an antenna 20. For example, when it is desired to convert each piece of sensing information acquired by the terminal device 6 or a notice that content has not been properly received on the terminal device 6 side into transmission information and transmit it to the terrestrial radio station 3, it is of course possible to select the optimal antenna 20 based on the positions of each antenna 20 that can be grasped via the current traveling position of the mobile object 2 and the position of the terrestrial radio station 3, as described above.

Figure 5 shows an example of a simulation in which the antenna 20 is composed of antennas 20a and 20b, and the terrestrial wireless stations 3a and 3b as shown in Figure 4, and basic information is transmitted from the terrestrial wireless station 3a, and actual content data is transmitted from the terrestrial wireless station 3b. The total data size transmitted from the terrestrial wireless station 3 is composed of the data size of the information from the terrestrial wireless station 3a and the data size of the later information from the terrestrial wireless station 3b. Here, a simulation is performed to see how much the reception efficiency can be improved by not receiving the later information from the terrestrial wireless station 3b as a result of checking the contents of the information. When the ratio of the data size of the information to the data size of the later information is set to 0.1 and 0.5, the reception efficiency is shown to be improved for the proportion of "unnecessary" information on the horizontal axis. In particular, when the ratio of the data size of the signal is 0.1, it can be seen that the reception efficiency is improved by two times when the proportion of "unnecessary" information is 40%.

REFERENCE SIGNS LIST 1 Mobile wireless communication system 2 Mobile object 3 Ground wireless station 4 Central control station 6 Terminal device 20 Antenna 21 Driving control unit 23 Traveling position acquisition unit 24 Selection unit

Claims (4)

In a mobile wireless communication system in which a moving object communicates wirelessly with an external ground wireless station,
The moving body is
an antenna arranged at two or more different positions in a traveling direction for wirelessly communicating transmission information with the ground radio station;
a terminal device for transmitting and receiving the transmission information to and from the antenna;
A traveling position acquisition means for acquiring a current traveling position;
a selection means for selecting an antenna for transmitting and receiving the transmission information to and from the terminal device based on the current traveling position acquired by the traveling position acquisition means and the position of the ground radio station,
The ground radio station is provided in two or more locations along a traveling direction,
the selection means selects, for each of the ground radio stations, an antenna for transmitting and receiving the transmission information to and from the terminal device, based on the positions of the antennas corresponding to the current traveling position acquired by the traveling position acquisition means and the positions of the ground radio stations, and determines, based on the transmission information received from a first ground radio station located on one side of the traveling direction, whether or not to transmit the transmission information from a second ground radio station located on the other side of the traveling direction to the terminal device.
A mobile wireless communication system comprising: The selection means acquires a position of each of the antennas multiple times according to the current traveling position acquired by the traveling position acquisition means, calculates a calculated position S from the acquired positions of each antenna ( _x1 , _x2 , ..., _xn ) based on the following formula (1) or (2), and selects an antenna for transmitting/receiving the transmission information to/from the terminal device based on the calculated position S and the position of the terrestrial radio station: S = _{a1 x1} + _{a2 xx2} + ... + _{an xn (} 1)
S=a ₁ ×x ₁ ×a ₂ ×x ₂ ×...×a _n x _n (2)
(a ₁ to a _n are predetermined coefficients, and n is the number of times the antenna position is acquired)
2. The mobile radio communication system according to claim 1, wherein: 3. The mobile radio communication system according to claim 1 or 2, characterized in that the terminal device combines transmission information received via one of the antennas with transmission information received via another of the antennas to form one transmission information. The moving object is a train that runs on a track,
The mobile wireless communication system according to any one of claims 1 to 3, wherein the ground wireless station is provided on a roadside of the railroad tracks and performs wireless communication in a millimeter wave band between the ground wireless station and the mobile object.

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