JP4343122B2 - Radio signal transmission system controller, radio signal transmission system - Google Patents

Description

  The present invention relates to a radio signal transmission system control apparatus and a radio signal transmission system including the radio signal transmission system control apparatus, and more particularly to a fixed radio apparatus that a mobile radio apparatus moving on a predetermined movement path is a radio signal transmission partner. The present invention also relates to a radio signal transmission system control device that can be switched reliably and a radio signal transmission system including the same.

For example, wireless communication such as a wireless LAN is used for communication with a high-speed moving body that moves at high speed along a predetermined track such as a vehicle traveling on a route. As an example for realizing such wireless communication, the following wireless signal transmission system can be considered.
A plurality of base stations are arranged along the trajectory. The communication area in which each of the base stations can communicate satisfactorily is limited to a predetermined range (at most a radius of several hundred meters) centered on each of the base stations, and the communication area covers the entire orbit at an interval. A plurality of base stations are arranged. The high-speed mobile unit (hereinafter simply referred to as a mobile unit) is equipped with a slave station for communicating with each of the base stations.
The mobile unit is connected to one base station close to itself among the plurality of base stations, and performs wireless communication between the nearest base station and the child station. Since the distance between the mobile body and each of the plurality of base stations changes with the movement of the mobile body, it is necessary to sequentially switch the base station to be connected to the closest one according to the movement. Such switching of connection target base stations is called handover. When the handover is appropriately performed, the mobile body can maintain a good communication state with each of the base stations.

FIG. 1 is a schematic configuration diagram of a conventional radio signal transmission system. Hereinafter, the configuration of the wireless signal transmission system as described above will be described with reference to FIG.
As shown in FIG. 1, a vehicle 2 is traveling along a route 1 laid along a predetermined track. The vehicle 2 is equipped with a slave station 2a for wireless communication. A plurality of base stations 3a, 3b, 3c,... Are provided along the route 1 in order to perform wireless communication with the traveling vehicle 2 via the slave station 2a. The base stations 3a, 3b, 3c... Are connected to a radio signal transmission system control device 5 through a control command transmission line 4. The wireless signal transmission system control device 5 controls each of the various base stations 3a, 3b, 3c... Including adjustment of the strength of the wireless signal used for communication with the vehicle 2.
Each of the base stations 3a, 3b, 3c... Has a finite (usually several hundred meters) communication area 6 that enables good communication, and the communication area 6 is the base stations 3a, 3b. , 3c... Spreading around each other. The base stations 3a, 3b, 3c,... Are arranged such that each of the communication areas 6 covers the route 1 and the communication areas 6 in two adjacent base stations slightly overlap on the route 1. .

Therefore, on the route 1, an area (hereinafter referred to as a single radio transmission area) capable of communicating with only one of the single base stations (the base stations 3a, 3b, 3c) and the two base stations The communication areas 6 overlap each other, and areas (hereinafter referred to as overlapping wireless transmission areas) in which one of the two base stations can be selected and communicated are alternately formed.
As the vehicle 2 moves, base stations to be connected (connected) for wireless communication via the slave station 2a are sequentially switched (that is, handed over). Handover occurs in the overlapping radio transmission area. For example, the vehicle 2 traveling in a single wireless transmission area in the communication area 6 by the base station 3a can perform wireless communication by connecting the slave station 2a and the base station 3a. When the slave station 2a reaches the overlapping radio transmission area by the communication area 6 of the base station 3a and the communication area 6 of the base station 3b due to the movement of the vehicle 2, the mobile station 2a moves in the overlapping radio transmission area. Meanwhile, the connection destination of the slave station 2a is handed over from the base station 3a to the base station 3b.

Hereinafter, switching conditions of the base station to which the slave station 2a is connected will be described.
The slave station 2a is connected to a signal processing device 2b that receives a radio signal from the slave station 2a and performs various processes on the radio signal, and performs switching control of a connection destination base station based on the received radio signal. ing.
When the slave station 2a reaches the overlapping radio transmission area, the slave station 2a receives the radio signal transmitted from the base station 3a that has been the counterpart of the radio communication and the radio signal transmitted from the base station 3b. . Usually, in a wireless LAN system, when wireless signals from multiple base stations are detected, there are base stations with better connection conditions (signal strength, radio wave state, communication speed, etc.) than the currently connected base station. When this is detected, the base station to be connected is generally switched, and the signal processing device 2b also switches the base station to be connected based on such a criterion.

By the way, when the slave station 2a alone receives a radio signal from the base station 3a and a radio signal from the base station 3b at the same time, it receives a signal obtained by superimposing these radio signals. In such a case, the superimposed signal is immediately separated into a radio signal transmitted from the base station 3a and a radio signal transmitted from the base station 3b, and the strengths of the two radio signals are compared. The connection destination cannot be determined. Such two wireless signals can be compared in strength when there is a clear difference between the strengths of the two wireless signals, for example, when the difference in strength is 15 dB or more.
FIG. 2 is a graph with respect to the reception position of the strength of the radio signals from the two base stations in the overlapping radio transmission area.
As shown in FIG. 2, the intensity of the radio signals from the two base stations is the same at point A with respect to the position change of the vehicle 2. Thereafter, as the vehicle 2 moves in the direction of the base station 3b, the intensity of the radio signal of the base station 3b is amplified, and the intensity of the radio signal of the base station 3a decreases. However, after passing through the point A, such a decrease or increase in the radio signal strength is very slow.
At the point A where the strength of the radio signal by the base station 3a and the strength of the radio signal by the base station 3b are reversed, the connection destination of the slave station 2a is handed over from the base station 3a to the base station 3b. Is ideal, but the actual handover for the above-mentioned reason is when the point A is reached after passing the point A far.

Accordingly, communication from the point A to the point B must be performed using the weak radio signal of the base station 3a, and there is a problem that an appropriate communication state cannot be maintained.
Thus, a wireless communication system capable of solving such a problem is disclosed in Patent Document 1.
According to the technique described in Patent Document 1, two slave stations are installed in one vehicle. While one of the two slave stations performs radio communication with the base station in the current communication area, the other slave station searches for a radio signal of the base station to be connected next. With such a configuration, it is possible to reliably compare the strengths of the radio signals received by each of the two slave stations. For example, when the hand reaches the point A shown in FIG. It is possible to make it over.
JP 2003-318765 A

However, in the technique disclosed in Patent Document 1 described above, it is necessary to provide two slave stations for each vehicle. Usually, in a traffic system, many vehicles run on the traffic system, and providing two slave stations for each vehicle in this way has a great hindrance in terms of costs such as introduction cost and management cost.
It is also conceivable that a GPS and a mobile phone module are mounted on the vehicle so that the vehicle can grasp its own position. In such a case, if the information on the point where the strengths of the radio signals from the two base stations are reversed is stored in advance, the location information determined by using the GPS and the mobile phone module is used. Based on this, it is possible to perform handover at the timing when the wireless signal strength reaches a point where the intensity is reversed. However, even in such a method, it is necessary to mount the GPS and the mobile phone module on all the vehicles on the transportation system, and thus have the same problems as the technique disclosed in Patent Document 1 described above.
Accordingly, the present invention has been made in view of the above circumstances, and the object of the present invention is to make a handover at an appropriate point as inexpensively as possible without making a major change to a moving device such as a vehicle. It is an object of the present invention to provide a radio signal transmission system control device capable of maintaining a good communication state, and a radio signal transmission system including the same.

In order to achieve the above-described object, the present invention provides a wireless signal transmitted in one or both directions between a mobile wireless device moving on a predetermined moving route and a plurality of fixed wireless devices arranged along the moving route. And when the mobile radio apparatus receives radio signals from a plurality of fixed radio apparatuses, radio signal transmission is performed to switch the fixed radio apparatus as a signal transmission partner on the basis of the intensity comparison of the radio signals. A radio signal transmission system control apparatus for controlling a system, wherein the mobile radio apparatus transmits a radio signal to both the upstream fixed radio apparatus and the downstream fixed radio apparatus that are adjacent in the moving direction of the mobile radio apparatus. A moving situation detecting means for detecting the arrival of overlapping wireless transmission areas where transmission is possible and its moving direction; and the moving situation detecting means allows the mobile radio apparatus to A signal strength adjusting means for lowering a relative strength of a radio signal of the upstream fixed wireless device with respect to the downstream fixed wireless device when it is detected that a multi-radio transmission area has been reached; and a plurality of the mobile wireless devices A wireless transmission area formed by the upstream fixed wireless device corresponding to the overlapping wireless transmission area in which arrival of the mobile wireless device is detected by the movement status detecting means, The presence of the other mobile radio apparatus by the single area presence detection means and the single area presence detection means for detecting whether or not the other mobile radio apparatus exists in the single radio transmission area that does not overlap with the other radio transmission area. Prohibiting the wireless signal strength from being lowered by the signal strength adjusting means for the fixed wireless device corresponding to the detected single wireless transmission area. A first signal strength adjusting limiting means is a radio signal transmission system control apparatus characterized by comprising comprises a.
As a result, when the mobile radio apparatus reaches the overlapping area of the communication area, the mobile radio apparatus is currently subject to signal strength of the fixed radio apparatus on the upstream side of the communication and the mobile object to be handed over A difference from the signal strength of the fixed wireless device on the downstream side is likely to occur, and prompt and appropriate handover is promoted.
In this case, there is no need to change the configuration or introduce a new device in the mobile device (vehicle or the like) on which the mobile wireless device is mounted. In addition, the mechanism for determining the position and traveling direction of the mobile device is provided in an ordinary traffic system (railway or the like), and the signal strength of the fixed wireless device (that is, the base station) can naturally be controlled. Therefore, a function for inputting the determination result of the determination mechanism to the control device to adjust the signal strength and a path, and whether the mobile wireless device has reached the overlapping area from the input information to the control device. Appropriate and quick handover can be obtained simply by making a cheap change of equipment such as adding a processing function to be detected, and a good communication state with the mobile device can be obtained.
Further, in the present invention, when a plurality of mobile radio apparatuses can exist as described above, even if a certain mobile radio apparatus reaches the overlapping radio transmission area, another mobile radio apparatus is determined based on the determination result by the determination mechanism. If it is determined that the mobile radio apparatus exists in a single radio transmission area capable of radio signal transmission only with the upstream fixed radio apparatus corresponding to the overlapping radio transmission area, the mobile radio apparatus corresponds to the single radio transmission area. The wireless signal strength of the fixed wireless device is prohibited from being lowered. As a result, even when a certain mobile radio apparatus is handed over, the fixed-side radio apparatus that is the original connection destination of the mobile radio apparatus is in communication with the other mobile radio apparatus during the communication with the other mobile radio apparatus. Problems such as a reduction in signal strength are prevented.

As an example of adjusting the relative strength of the radio signal, the strength of the radio signal of the upstream fixed radio device is lowered, or the strength of the radio signal of the upstream fixed radio device is lowered and the radio of the fixed radio device on the downstream side is reduced. Although it is possible to increase the signal intensity, these can be properly used according to the use environment (situation). When reducing the strength of the wireless signal of the upstream fixed wireless device, when another mobile wireless device reaches the communication area of the fixed wireless device, the wireless signal is again transmitted to a strength that enables wireless signal transmission. The signal strength needs to be increased.
When the strength of the radio signal of the fixed wireless device on the upstream side is lowered, the upstream signal is transmitted to a level at which a radio signal transmission is possible once and the strength of the radio signal of the fixed radio device on the downstream side is clearly different It is desirable to gradually reduce the strength of the wireless signal of the upstream fixed wireless device, for example, by reducing the strength of the wireless signal of the fixed wireless device on the side and reducing it to zero after the handover occurs. In the case where the radio signal suddenly disappears, it is known that handover is not properly performed. In this way, the strength of the radio signal of the upstream fixed radio apparatus is gradually reduced. Then, a stable handover can be caused.

Further, when the strength of the wireless signal of the upstream fixed wireless device is lowered, in order to avoid interference between the wireless signal transmission system and another wireless LAN system, or to the wireless signal transmission system via the wireless LAN. In order to prevent illegal intrusions or to save energy, it is desirable to reduce the strength to almost zero.
Further , even if the mobile radio apparatus is a fixed radio apparatus on the downstream side, the fixed radio apparatus is fixed if it is the fixed radio apparatus on the upstream side with respect to another mobile radio apparatus at the same time. It should be prohibited that the wireless signal strength of the wireless device is reduced.
The present invention may be understood as a radio signal transmission system including the radio signal transmission system control device as described above.

  According to the present invention, a base station (fixed radio apparatus) capable of adjusting signal strength used for radio signal transmission and its control apparatus, or a discriminating mechanism for discriminating the position and traveling direction of a mobile body (mobile radio apparatus), etc. Therefore, it is possible to appropriately obtain a handover of the mobile radio apparatus by simply changing an inexpensive facility with respect to a configuration that an ordinary traffic system should have. A good communication state can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a schematic configuration diagram of a conventional radio signal transmission system, FIG. 2 is a graph showing the behavior of radio signal strengths from two base stations in the overlapping radio transmission area with respect to the reception position, and FIG. 4 is a schematic configuration diagram of a radio signal transmission system including a radio signal transmission system control device according to the invention, FIG. 4 is a schematic configuration diagram of a radio signal transmission system when there are a plurality of vehicles, and FIG. 6 is a schematic configuration diagram of a radio signal transmission system when traveling in a vehicle, FIG. 6 is a data configuration diagram of a vehicle information list input to the radio signal transmission system according to the embodiment of the present invention, and FIG. 7 is an embodiment of the present invention. FIG. 8 is a data configuration diagram of radio transmission area information of each base station stored in advance by the radio signal transmission system control apparatus according to FIG. 8, and FIG. FIG. 9 is a data configuration diagram of radio signal strength setting information of each base station set by the transmission system control device, and FIG. 9 is a radio signal strength adjustment control process of the base station by the radio signal transmission system control device according to the embodiment of the present invention. It is a flowchart which shows the procedure of. In addition, about the structure similar to a prior art example, the code | symbol same as the code | symbol used in description of the prior art example shall be used.

(1) Differences in configuration between the wireless signal transmission system control device according to the present invention and the conventional example.
FIG. 3 is a schematic configuration diagram of a radio signal transmission system including a radio signal transmission system control apparatus according to the present invention. Hereinafter, with reference to FIG. 3, the difference in configuration between the radio signal transmission system control device according to the present invention and the radio signal transmission system in the conventional example will be described.
A general railway (an example of a transportation system) as shown in FIG. 3 has the following configuration for determining the position of each vehicle on the route and the moving direction thereof. The route 1 is a route on which the vehicle 2 travels. A leaky coaxial cable 7 is provided so as to be parallel to the route 1.
The leaky coaxial cable 7 functions as a wireless antenna that transmits and receives weak radio waves over its entire length. On the other hand, the vehicle 2 is equipped with the following vehicle position detecting device. That is, the vehicle position detection device transmits information on the travel distance and travel direction of the vehicle measured from the number of rotations of the wheels and the like to the on-line detection device 8 via the leaky coaxial cable 7. Thereby, the presence line detection device 8 can detect the position and the direction of movement of the vehicle 2.
On the other hand, the position of the vehicle 2 may be detected using the leaky coaxial cable 7 as follows.
A radio wave is radiated from the leaky coaxial cable 7 over its entire length, and a part of the radio wave is radiated by the vehicle 2. Such radiated radio waves are received again by the leaky coaxial cable 7. Further, even if the radiated radio wave is inputted by the standing line detection device 8 connected to the leaky coaxial cable 7, the position and movement direction of the vehicle 2 can be detected by the standing line detection device 8. good.

Incidentally, the wireless signal transmission system A including the wireless system control device according to the embodiment of the present invention shown in FIG. 3 is mounted on the vehicle 2 moving on the route 1 (predetermined moving route). A slave station 2a (an example of a mobile radio apparatus) is a system for performing wireless communication (bidirectional signal transmission) with a plurality of base stations 3a, 3b, 3c... Arranged along the route 1. In the radio signal transmission system A, when the slave station 2a receives radio signals from two or more of the plurality of base stations 3a, 3b, 3c..., Signal transmission is performed based on a comparison of the strengths of those radio signals. Are selected (switched) among the base stations 3a, 3b, 3c. Specifically, when the relative strength of the radio signals from the two base stations is greater than 15 dB, the signal processing device 2b connected to the slave station 2a has the signal strength of the two base stations. The larger one is connected as a counterpart of radio signal transmission with the slave station 2a. The radio signal transmission system control device 5 ′ according to the present invention is a control device that controls the radio signal transmission system A. Specifically, the CPU of the calculation unit, the storage unit that stores various information, and the base It comprises an I / O unit that outputs a control command for signal intensity adjustment to the stations 3a, 3b, 3c.
The presence line detection device 8 is connected via a communication cable 9 to a control command transmission line 4 that connects the radio signal transmission system control device 5 ′ to the base stations 3a, 3b, 3c. As a result, a vehicle information list to be described later by the presence line detection device 8, that is, the positions of all the vehicles 2 and their moving directions are input to the radio signal transmission system control device 5 ′.

(2) Outline of the radio signal transmission system control device according to the embodiment of the present invention.
As described in the description of the conventional example, when the vehicle has one slave station, the base station that is currently the target of communication is switched to the next base station (to be handed over). It is necessary that the strength of the signal clearly exceeds (for example, 15 dB or more) the strength of the radio transmission signal of the base station currently being communicated with. Therefore, the present invention is characterized in that prompt and reliable handover is promoted by adjusting the strength of the radio signal of each of the base stations in a timely manner without any change on the vehicle side. .
First, the CPU 2 (an example of movement status detection means) of the radio signal transmission system 5 ′ uses the information input from the presence line detection device 8 used in the general railway as described above to use the vehicle 2. And the slave station 2a (mobile radio apparatus) mounted on the base station 3a, 3b, 3c,... Adjacent to the upstream base station (fixed radio apparatus) and the downstream base station in the moving direction. In both cases, it is determined (detected) that it has reached an overlapping wireless transmission area where wireless signal transmission is possible and its moving direction.

Based on the determination result, when the CPU detects that the slave station 2a (mobile radio apparatus) has reached the overlapping radio transmission area according to the processing procedure described later in detail, the downstream side The signal strength of each base station is set so as to lower the relative strength of the radio signal of the upstream base station with respect to the base station (fixed radio apparatus), and the base stations 3a, 3b, 3c... Are controlled according to the setting. To do. The CPU for setting the signal strength and the I / O unit that outputs a control command to the base stations 3a, 3b, 3c... According to the setting are examples of signal strength adjusting means.
There are various specific settings for reducing the relative strength of the radio signal of the upstream base station with respect to the downstream base station. In this embodiment, the upstream base station (fixed) The signal strength adjustment method is employed in which the wireless signal strength of the wireless device is lowered and the downstream wireless signal is raised.

(3) Regarding the adjustment process of the radio signal intensity when there are a plurality of vehicles.
When there are a plurality of the vehicles 2, for example, when the vehicles 2 pass each other, one of the base stations 3 a, 3 b, 3 c... Communicates with the two (or more) slave stations 2 a. May be performed. 4 and 5 are schematic configuration diagrams in the case where there are a plurality of vehicles. As shown in FIG. 4, the vehicle 2 has reached an overlapping wireless transmission area where communication areas 6 of the base station 3 a and the base station 3 b overlap. The base station 3 a is communicating with a vehicle 2 ′ different from the vehicle 2. In order to make sure that the vehicle 2 is handed over, it is desirable to reduce the strength of the radio signal of the base station 3a, but doing so will stop the transmission of the radio signal with the vehicle 2 '. In such a case, control for lowering the signal strength of the base station 3a is prohibited.
That is, when a plurality of the slave stations 2a (mobile radio devices) can exist, the CPU 2 (an example of movement status detection means) causes the vehicle 2 to be connected to the base station 3a on the upstream side and the base station on the downstream side. When it is detected that an overlapping wireless transmission area with the station 3b has been reached, the CPU (single area presence detecting means) also uses the information input from the presence line detecting device 8 to It is determined (detected) whether or not another vehicle 2 ′ exists in the single wireless transmission area where only the station 3a can transmit wireless signals.
The CPU determines the base station 3a (fixed radio apparatus) corresponding to the single radio transmission area in which the presence of the vehicle 2 'is detected based on such a determination result (detection result by the single area presence detection means). Sets the signal strength of each base station so as to prohibit the radio signal strength from being lowered. The I / O unit that outputs a control command to the base stations 3a, 3b, 3c,... According to the CPU and the settings set thereby is an example of a first signal strength adjustment limiting unit.

  Further, as shown in FIG. 5, when a plurality of routes 1 are laid, it is conceivable that another vehicle 2 ″ travels behind the vehicle 2 substantially in parallel with the vehicle 2. In this case, as shown in FIG. 5, the vehicle 2 has reached an overlapping radio transmission area by the base station 3b and the base station 3c, and the vehicle 2 ″ is also the base station 3a and the base station. It is also conceivable to reach the overlapping radio transmission area according to 3c. At this time, the base station 3b (fixed wireless device) is on the downstream side with respect to the slave station 2a (mobile wireless device) mounted on the vehicle 2, and is simultaneously mounted on the vehicle 2. It is on the upstream side with respect to the slave station 2a. Even in such a case, if the strength of the radio signal of the base station 3b is lowered, the transmission of the radio signal with the vehicle 2 ″ is stopped, so that it is prohibited to lower the radio signal of the base station 3b. The I / O unit that outputs a control command to the base stations 3a, 3b, 3c,... According to the CPU and the settings set thereby is an example of second signal strength adjustment limiting means. It is.

(4) About various data structures.
FIG. 6 is a data configuration diagram of a vehicle information list input from the presence line detection device 8 to the radio signal transmission system control device 5 ′. FIG. 7 is a data configuration diagram of information on the radio transmission area of each base station stored in advance by the radio signal transmission system control device 5 ′ according to the embodiment of the present invention. As described above, the presence line detection device 8 generates a vehicle information list indicating the position and moving direction of each vehicle 2 and transmits it to the radio signal transmission system control device 5 ′. As shown in FIG. 6, the vehicle information list is obtained by associating identification information 101 of each vehicle 2 with position coordinate information 102 and movement direction information 103 for each vehicle.
Further, the storage unit of the radio signal transmission system control device 5 ′ stores information on the overlapping radio transmission area and the single radio transmission area (radio transmission area information) as shown in FIG. As shown in FIG. 7, the radio transmission area information is the same as the coordinate information 201 on the route 1, if the coordinate area is the single radio transmission area, the assigned base station information 202, while the coordinate area is In the overlapping radio transmission area, set information of uplink base station information 203 and downlink base station information 204 is associated with each other. Note that “up” and “down” here refer to a predetermined direction on the route 1, and have different meanings from “upstream” and “downstream” in the moving direction of the vehicle 2.

From the above, the radio signal transmission system control device 5 ′ determines all the vehicles from the vehicle information list input from the on-line presence detection device 8 and the radio transmission area information stored in advance in the storage unit. 2. Each vehicle area information of each moving direction and which base station is in the single radio transmission area or between which two base stations is in the overlapping radio transmission area is generated.
Here, FIG. 8 is a data configuration diagram of radio signal strength setting information of each base station set by the radio signal transmission system control device 5 ′. On the basis of the discrimination information as described above, the radio signal transmission system control device 5 ′ uses the radio signal strength setting information (radio signal) for each of the base stations 3a, 3b, 3c... As shown in FIG. Intensity setting information) is set, and the intensity of the radio signals of the base stations 3a, 3b, 3c... Is controlled based on the radio signal intensity setting information.

As shown in FIG. 8, the wireless signal strength setting information is information in which current signal strength information 302 and next signal strength information 303 are associated with base station identification information 301.
The current signal strength information 302 is information representing the current radio signal strength of each of the base stations 3a, 3b, 3c... In three levels of “maximum level”, “stop level”, and “maximum level—10 dB”. is there. On the other hand, the next signal strength information 303 is information representing the strength of the radio signal set based on the vehicle area information in three levels, and the current signal strength information 302 is a predetermined time. Is updated to the contents of the next signal strength information 303 as time elapses.
The “maximum level” indicates a state in which the intensity of the radio signal of the base station is sufficient for communication with the slave station 2a. This does not necessarily indicate that each of the base stations 3a, 3b, 3c... Outputs a radio signal with the maximum intensity that can be transmitted, depending on the surrounding environment of each of the base stations 3a, 3b, 3c. , It is sufficient to set the wireless signal strength sufficient for communication. On the other hand, the “stop level” indicates a state where transmission of the wireless signal is stopped, that is, a state where the strength of the wireless signal is set to substantially zero. As described above, the radio signals used in the vicinity of the radio signal transmission system A are not reduced by reducing the intensity of the radio signals of the base stations 3a, 3b, 3c,. It is possible to suppress the influence on the LAN system and the like as much as possible. It is also desirable from the viewpoint of energy saving to reduce the intensity of the radio signal to substantially zero.

Furthermore, “maximum level−10 dB” is a state in which communication with the slave station 2a is possible, but the signal strength is lowered by 10 dB compared to the state of “maximum level”. When the vehicle 2 is in the overlapping wireless transmission area, “maximum level −10 dB” is set for the upstream base station, and “maximum level” is set for the downstream base station, In the overlapping radio transmission area, the strength of the radio signal by the base station on the downstream side is increased, and the handover is quickly performed.
Further, the strength of the radio signal is not lowered from “maximum level” to “stop level” by updating the setting information once, but from “maximum level” to “maximum level−10 dB”, “maximum level−10 dB”. The radio signal is gradually lowered from “stop level” to “stop level”.
When the radio signal from the base station that is currently the radio signal transmission partner suddenly stops, the slave station 2a cannot compare the strength with the radio signal from the base station that is the next signal transmission partner, There is a possibility of hindering handover. However, as described above, such a problem can be avoided by gradually lowering the signal intensity via “maximum level−10 dB” instead of suddenly setting the wireless signal to the “stop level”.

(5) Processing procedure for setting wireless signal strength setting information.
FIG. 9 is a flowchart showing the procedure of the radio signal strength adjustment process of the base station by the radio signal transmission system control apparatus according to the embodiment of the present invention. Hereinafter, the procedure of setting the wireless signal strength setting information by the wireless signal transmission system control device 5 ′ will be described in detail with reference to FIG. Note that the processing of each procedure (step) in the flowchart shown in FIG. 9 is realized by the CPU, the storage unit, the I / O, etc. of the wireless signal transmission system control device 5 ′ as will be described in detail later. Is done. Here, S1, S2,... In FIG. 9 indicate process numbers (steps), which are executed from the process of step S1 when the radio signal transmission system A starts wireless communication.

In step S1, the CPU generates area information for each vehicle based on the vehicle information list input from the presence line detection device 8 and the wireless transmission area information stored in the storage unit.
In step S2 following step S1, the CPU temporarily sets the next signal strength information 303 in the radio signal strength setting information to “stop level” for all the base stations 3a, 3b, 3c. .
Subsequent steps S3 to S9 are sequentially performed on all the vehicles described in the vehicle information list.
In step S3 following step S2, the CPU determines whether or not the vehicle 2 is located in the single wireless transmission area. If it is determined that it is located in the single radio transmission area (YES in S3), the process proceeds to step S5. On the other hand, if it is determined that it is not located in the single wireless transmission area (NO in S3), the process proceeds to step S4.

In step S5, the next signal strength of the base station corresponding to the single radio transmission area determined that the vehicle 2 is located in step S3 of the base stations 3a, 3b, 3c. Level "is set. When step S5 is completed, the process proceeds to step S9.
On the other hand, in step S4, the CPU determines whether or not the vehicle 2 is located in the overlapping wireless transmission area. If it is determined that it is located in the overlapping wireless transmission area (YES in S3), the process proceeds to step S6. On the other hand, if it is determined that it is not located in the overlapping wireless transmission area (NO in S4), the process proceeds to step S9.
In step S6, the moving direction information 103 of the vehicle 2 is referred to, and the downstream base station and the upstream base station are determined for the two base stations corresponding to the overlapping wireless transmission area. The next signal strength of the downstream base station is set to the “maximum level” by the CPU. This indicates that the strength of the radio signal is increased for a new base station to which the vehicle 2 (correctly the slave station 2a) is connected. When the process of step S6 is completed, the process proceeds to step S7.

In the process of step S7, whether the next signal strength is already set to the “maximum level” for the upstream base station (that is, the base station corresponding to the single radio transmission area where another vehicle is located). Or whether it is the downstream base station). If it is already set to the “maximum level” (YES in S7), it is determined that radio signal transmission is being performed with another vehicle, or that radio signal transmission of the other vehicle will be performed next time (that is, It is determined that it is in the state shown in FIGS. 4 and 5), and the process proceeds to step S9 without changing the setting.
On the other hand, if it is not set to “maximum level” (set to “stop level”) (NO in S7), the process proceeds to step S8. In step S8, the next signal strength is set to “maximum level−10 dB” by the CPU. In this way, with respect to the upstream fixed wireless device, the wireless signal strength is not suddenly set to the “stop level”, but the “maximum level−10 dB” is temporarily set in order to gradually reduce the wireless signal strength. "Is set. Further, after the vehicle 2 has passed through the overlapping wireless transmission area, the intensity of the wireless signal is lowered to the “stop level” by the process of step S2 described above (strictly speaking, the strength of the wireless signal is set to the “stop level” in step S2). The set next signal intensity information 303 is maintained as it is). When the process of step S8 is completed, the process proceeds to step S9.
In step S9, the CPU determines whether or not the loop processing from step S3 to step S9 has been completed for all the vehicles described in the vehicle information list. If it is determined that the process has been completed (YES in S9), the process proceeds to step S10. On the other hand, when it is determined that the loop processing has not been completed for all the vehicles (NO in S9), the process returns to step S3.
In step S10 following step S9, the next signal strength information set in the loop processing in steps S3 to S9 is set as the new current signal strength. Further, a control command for each of the base stations 3a, 3b, 3c,... Based on the new current signal strength is output via the I / O unit.

In the above-described embodiment, the railway is described as an example of the transportation system. However, the present invention can also be applied to a linear motor car transportation system and a radio signal transmission system with a vehicle in a monorail transportation system. .
In the above-described embodiment, an example in which wireless communication is performed between a base station and a slave station is disclosed, but one of the slave station and the base station outputs a radio signal and the other receives it. The present invention can also be applied to a system in which unidirectional signal transmission is performed in a so-called broadcast form.

The schematic block diagram of the radio signal transmission system in a prior art example. The graph which shows the behavior with respect to the receiving position of the intensity | strength of the radio signal from each of two base stations in an overlapping radio | wireless transmission area. 1 is a schematic configuration diagram of a radio signal transmission system including a radio signal transmission system control device according to the present invention. The schematic block diagram of the radio | wireless signal transmission system in case a some vehicle exists. The schematic block diagram of the radio | wireless signal transmission system in case a some vehicle drive | works in parallel. The data block diagram of the vehicle information list input into the radio signal transmission system concerning an embodiment of the invention. The data block diagram of the information of the radio transmission area of each base station memorize | stored beforehand by the radio signal transmission system control apparatus which concerns on embodiment of this invention. The data block diagram of the radio signal strength setting information of each base station set by the radio signal transmission system control device according to the embodiment of the present invention. The flowchart which shows the procedure of the radio signal strength adjustment control processing of the base station by the radio signal transmission system control device according to the embodiment of the present invention.

Explanation of symbols

A ... Radio signal transmission system B comprising a radio signal transmission system controller according to an embodiment of the present invention ... Radio signal transmission system 1 comprising a radio signal transmission system controller in the prior art ... Route 2 ... Vehicle 2a ... child Station 2b ... Signal processing device 3 ... Base station 4 ... Control command transmission line 5 ... Radio signal transmission system control device 5 'in the conventional example ... Radio signal transmission system control device 6 according to the embodiment of the present invention ... Communication region 7 ... Leakage coaxial cable 8 ... presence line detection device 9 ... communication cable

Claims (7)

A mobile radio apparatus moving on a predetermined movement path transmits a radio signal in one or both directions with a plurality of fixed radio apparatuses arranged along the movement path, and the mobile radio apparatus A radio signal transmission system control device that controls a radio signal transmission system that switches between the fixed radio devices as signal transmission counterparts based on a comparison of the strengths of the radio signals when receiving radio signals from a plurality of the fixed radio devices There,
The mobile radio apparatus has reached an overlapping radio transmission area where radio signals can be transmitted to both the fixed radio apparatus on the upstream side and the fixed radio apparatus on the downstream side adjacent to each other in the moving direction of the mobile radio apparatus; and Movement status detection means for detecting the movement direction;
When the movement status detection unit detects that the mobile radio apparatus has reached the overlapping radio transmission area, the relative strength of the radio signal of the upstream fixed radio apparatus with respect to the downstream fixed radio apparatus is reduced. A signal strength adjusting means;
Radio transmission formed by the upstream fixed radio device corresponding to the overlapping radio transmission area in which arrival of the mobile radio device is detected by the movement status detection means when a plurality of the mobile radio devices can exist A single area presence detecting means for detecting whether or not there is another mobile radio apparatus in a single wireless transmission area that is an area and does not overlap with another wireless transmission area;
Prohibiting the signal strength adjusting means from lowering the radio signal strength of the fixed radio device corresponding to the single radio transmission area in which the presence of the other mobile radio device is detected by the single area presence detecting means. A signal strength adjustment limiting means;
A radio signal transmission system control device comprising:   2. The radio signal transmission system control device according to claim 1, wherein the signal strength adjusting unit lowers the strength of the radio signal of the fixed radio device on the upstream side.   The radio signal transmission system control device according to claim 2, wherein the signal strength adjusting means gradually reduces the strength of the radio signal of the upstream fixed radio device.   4. The signal strength adjusting unit according to claim 2, wherein the signal strength adjusting unit lowers the strength of the wireless signal of the upstream fixed wireless device and increases the strength of the wireless signal of the downstream fixed wireless device. The radio signal transmission system control device described.   The radio signal transmission system control device according to any one of claims 2 to 4, wherein the signal strength adjusting means lowers the strength of the radio signal of the upstream fixed radio device to substantially zero. When there are a plurality of mobile radio apparatuses, the mobile radio apparatus is a fixed radio apparatus on the downstream side according to the detection status of the movement status detection means, and at the same time, other mobile radio apparatuses On the other hand, the fixed wireless device which is the fixed wireless device on the upstream side includes second signal strength adjustment limiting means for prohibiting the wireless signal strength from being lowered by the signal strength adjusting means. The radio signal transmission system control device according to any one of 1 to 5 . A mobile radio apparatus moving on a predetermined movement path transmits a radio signal in one or both directions with a plurality of fixed radio apparatuses arranged along the movement path, and the mobile radio apparatus A radio signal transmission system control device that controls a radio signal transmission system that switches between the fixed radio devices as signal transmission counterparts based on a comparison of the strengths of the radio signals when receiving radio signals from a plurality of the fixed radio devices A radio signal transmission system comprising the radio signal transmission system control device according to any one of claims 1 to 6 .

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