KR20060087448A - Wireless signal transmission system and control device thereof - Google Patents

Abstract

In a traffic system such as a railway, an area in which the mobile radio apparatus overlaps the communication areas of the two fixed radio apparatuses using information from a device for determining the position and travel direction of the mobile radio apparatus normally installed on the movement route. Is detected, and when the mobile radio apparatus reaches the area, the relative strength of the radio signal of the upstream fixed radio apparatus with respect to the fixed radio apparatus on the downstream side of the mobile radio apparatus is lowered. An apparatus on the mobile side such as a vehicle is provided with a wireless signal transmission system that enables handover at an appropriate point as cheaply as possible without making a major change, thereby maintaining a good communication state.

Vehicle, route, communication area, leaky coaxial cable, re-wire detection device, base station, local station

Description

Wireless signal transmission system and its control device {WIRELESS SIGNAL TRANSMISSION SYSTEM AND CONTROL DEVICE THEREOF}

1 is a schematic configuration diagram of a radio signal transmission system in a conventional example.

Fig. 2 is a graph showing the behavior of a reception position of radio signal strength from each of two base stations in a redundant radio transmission region.

3 is a schematic configuration diagram of a wireless signal transmission system according to the present invention.

4 is a schematic configuration diagram of a wireless signal transmission system in a case where a plurality of vehicles exist.

Fig. 5 is a schematic configuration diagram of a wireless signal transmission system in the case where a plurality of vehicles travel in parallel.

6 is a data configuration diagram of a vehicle information list input to a wireless signal transmission system according to an embodiment of the present invention.

Fig. 7 is a data configuration diagram of information of radio transmission areas of base stations stored in advance by the radio signal transmission system control apparatus according to the embodiment of the present invention.

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 according to the embodiment of the present invention.

Fig. 9 is a flowchart showing the procedure of the adjustment control processing of the radio signal strength of the base station by the radio signal transmission system control device according to the embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: Route

2: vehicle

2a: marks

2b: signal processing unit

3a, 3b, 3c... : Base station

4: control command transmission line

5: wireless signal transmission system control unit

6: communication area

7: leakage coaxial cable

8: rewire detection device

9: communication cable

101: identification information

102: position coordinate information

103: movement direction information

201: coordinate information

202: base station information in charge

203: rising base station information

204: falling base station information

302, 303: signal strength information

[Document 1] Japanese Unexamined Patent Publication No. 2003-318765

The present invention relates to a wireless signal transmission system and a wireless signal transmission control apparatus used therefor. In particular, the present invention relates to a radio signal transmission system and a radio signal transmission control device used therein, which enable a mobile radio device moving on a predetermined movement path to quickly and reliably change a fixed radio device to which radio signal transmission is to be made.

For example, wireless communication such as a wireless LAN is used for communication with a high-speed moving body moving at a high speed in accordance with a predetermined track such as a vehicle traveling on a route. As an example of realizing such wireless communication, the following wireless signal transmission system is considered.

A plurality of base stations are arranged along the trajectory. A communication area capable of communicating well with each of the base stations is limited to a predetermined range (only a radius of 100 m) centering around each of the base stations, and the plurality of communication areas are spaced at intervals covering all of the tracks. The base station is deployed. Further, the high speed mobile unit (hereinafter, simply referred to as mobile unit) is equipped with a local station for communicating with each of the base stations.

The mobile body connects with one base station close to itself among the plurality of base stations, and performs wireless communication between the base station closest to the base station. Since the mobile object changes its distance from each of the plurality of base stations with its movement, it is necessary to sequentially switch the base stations to be connected to the closest ones according to the movement. The switching of the connection target base station is called handover. By appropriate handover, the mobile can be maintained in good communication with each of the base stations.

1 is a schematic configuration diagram of a radio signal transmission system in a conventional example.

Here, an area (hereinafter referred to as a sole radio transmission area) in which only one base station (the base stations 3a, 3b, and 3c) can communicate on the route 1, and the communication area 6 of two base stations. The superimposed and alternately formed areas (hereinafter, redundant radio transmission areas) in which one of the two base stations can communicate with each other are formed. With the movement of the vehicle 2, the base stations targeted for wireless communication via the local station 2a (connected) are switched in turn (i.e., handover).

Hereinafter, the switching conditions of the base station 2a connected to the base station 2 and the like will be described.

When the local station 2a reaches the redundant radio transmission area in which communication between the base station 3a and the base station 3b is possible, the station 2a transmits from the base station 3a, which is the counterpart of the wireless communication up to that point. The received radio signal and the radio signal transmitted from the base station 3b. Generally, in a wireless LAN system, when a wireless signal from a plurality of base stations is detected, when a base station with better connection conditions (signal strength, radio wave state, communication speed, etc.) than the currently connected base station exists, the connection is detected. It is common to switch the base station to be used, and the signal processing apparatus 2b also switches the connection destination base station on the basis of such determination.

By the way, when the station 2a alone receives the radio signal from the base station 3a and the radio signal from the base station 3b at the same time, the radio signal received by the radio signal is received. In such a case, the polymerized 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 to determine a good connection destination. Can not. Such a comparison of the strengths of the two radio signals becomes possible when a clear difference is given to the strengths of the two radio signals, for example, when the difference in the intensity becomes 15 dB or more.

The reason for this is as follows. In general, when the wireless LAN service is to be provided to the own station of the mobile object, the signal strength easily varies from several dB to several tens of dB depending on the reception state of the own station. Therefore, in order to prevent erroneous switching operation due to a change in signal strength, it is necessary to prepare a margin of 10 dB to 15 dB to make a judgment. Indeed, standard wireless LAN systems are designed to work like that.

2 is a graph of the reception position of the radio signal strength from two base stations in the redundant radio transmission region.

As shown in Fig. 2, for the position change of the vehicle 2, the strengths of the radio signals from the two base stations are equal at the point A. Then, with the movement of the vehicle 2 toward the base station 3b, the strength of the radio signal of the base station 3b is amplified, and the strength of the radio signal of the base station 3a is decreased. However, after passing through point A, the decrease or increase in this wireless signal strength is very slow.

At 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 station 2a is connected from the base station 3a to the base station 3b. Although handing over is ideal, the actual handover for the above-described reasons is the point of time passing far beyond the point A and reaching the point B.

Therefore, from point A to point B, there is a problem that communication must be performed using a weak radio signal of the base station 3a, and an appropriate communication state cannot be maintained.

Then, as a wireless communication system which can solve such a problem, what was described in Unexamined-Japanese-Patent No. 2003-318765 is known.

According to the technique described in the above patent publication, two marks are provided in one vehicle. While one station of the two stations performs wireless communication with the base station in the current communication area, the other station searches for a radio signal of the base station to be connected next. With this configuration, it is possible to reliably compare the strengths of the radio signals received by each of the two stations, and to hand over at an appropriate timing, for example, when the point A shown in Fig. 2 is reached. Do.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2003-318765

However, in the technique disclosed in Japanese Patent Laid-Open No. 2003-318765, it is necessary to provide two marks for each vehicle. Usually, in a traffic system, many vehicles run the said traffic system, and providing two tracks for each vehicle in this way has a big problem in terms of costs such as introduction cost and management cost.

It is also conceivable that the vehicle is equipped with a GPS and a mobile phone module, which enables the vehicle to grasp its position. In this case, if the information of the point where the strengths of the radio signals from the two base stations are reversed is stored in advance, the radio signal of the radio signal is based on its own position information determined using the GPS and the cellular phone module. It is possible to hand over at the timing of reaching the point where the intensity is reversed. However, even in such a method, it is necessary to mount the GPS and the mobile telephone module in all of the vehicles on the transportation system, and suffer from the same problems as those described in Japanese Patent Laid-Open No. 2003-318765.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to enable handover at an appropriate point as cheaply as possible without making a large change to a device on the mobile side such as a vehicle, whereby There is provided a wireless signal transmission system control device capable of maintaining a communication state and a wireless signal transmission system having the same.

In order to achieve the above object, the present invention is a wireless signal transmission system, and in one or both directions between a mobile wireless device moving on a predetermined moving path and the mobile wireless device arranged in plural along the moving path. The fixed radio apparatus for transmitting radio signals, and the fixed radio apparatus as a partner of signal transmission based on a comparison of the strengths of the radio signals when the mobile radio apparatus receives radio signals from a plurality of the fixed radio apparatuses. And a wireless signal transmission system control device that performs control to switch devices, wherein the strength of the radio signal emitted by the fixed radio device to the mobile radio device is variable, and the radio signal transmission system control device is the mobile radio device. Is adjacent to the upstream side in the moving direction of the mobile radio apparatus. Any of the fixed radio apparatus and the downstream fixed radio apparatus has reached a redundant radio transmission region capable of transmitting a radio signal, and moving status detecting means for detecting a moving direction thereof; And when it is detected that the mobile radio apparatus has reached the redundant radio transmission region, signal strength adjusting means for lowering the relative strength of the radio signal of the upstream fixed radio apparatus with respect to the downstream fixed radio apparatus.

In addition, here, the back side of the advancing direction of the said mobile radio apparatus is called an upstream side, and the front side of the advancing direction of the said mobile radio apparatus is called a downstream side.

According to the above configuration, when the mobile radio apparatus reaches the overlapped area of the communication area, the downstream side that is the target of signal strength and handover of the upstream fixed radio apparatus with which the mobile radio apparatus is currently communicating. The difference with the signal strength of the fixed wireless device is easily given, which facilitates quick and proper handover.

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 device is mounted. In addition, the mechanism for determining the position and the traveling direction of the mobile side device is provided in a normal traffic system (railroad or the like), and it is naturally considered that the signal strength of the fixed side radio device (that is, the base station) can also be controlled. Therefore, addition of a function and a path for inputting the determination result of the determination mechanism to the control device to adjust the signal strength, and detecting whether the mobile wireless device has reached the overlapped area from the input information to the control device. It is possible to obtain an appropriate and quick handover only by making an obviously inexpensive facility change, such as adding a processing function to be performed, and obtain a good communication state with the mobile device.

As an example of adjusting the relative strength of the radio signal, the strength of the radio signal of the upstream fixed radio device or the strength of the radio signal of the upstream fixed radio device is decreased while Although it is conceivable to increase the strength of the radio signal, these can be appropriately classified according to the use environment (situation) or the like. When the strength of the radio signal of the upstream fixed radio device is reduced, when the other mobile side radio device reaches the communication area of the fixed radio device, the strength of the radio signal is such that the radio signal transmission is possible. It is necessary to raise again.

When the strength of the radio signal of the upstream fixed radio device is lowered, the radio signal can be transmitted once and the strength of the radio signal of the downstream fixed radio device is maintained at such a level that a clear difference is provided. It is preferable to gradually lower the strength of the radio signal of the upstream fixed radio device, such as to decrease the strength of the radio signal of the upstream fixed radio device and to zero after handover occurs. It is known that when the radio signal is suddenly lost, handover is not performed properly. However, if the strength of the radio signal of the upstream fixed radio device is gradually decreased in this way, a stable handover can be generated. have.

In addition, when the intensity of the radio signal of the upstream fixed radio device is lowered, in order to avoid interference between the radio signal transmission system and other radio LAN systems, it is illegal to the radio signal transmission system via the radio LAN. In order to prevent phosphorus intrusion, or to save energy, it is preferable to lower to approximately zero strength.

By the way, when there can exist a plurality of said mobile radio apparatuses, even if a certain mobile radio apparatus reaches | attains the said redundant radio transmission area | region, another mobile radio | wireless device is based on the determination result by the said discrimination mechanism in the said redundant radio transmission area | region. If it is determined that it exists in a single wireless transmission area capable of wireless signal transmission only to the corresponding upstream fixed wireless device, the wireless signal strength is inhibited from being lowered for the fixed wireless device corresponding to the single wireless transmission area. Needs to be. As a result, even when any mobile radio device is handed over, the strength of the radio signal of the fixed radio device decreases while the fixed-side radio device, which is the original connection destination of the mobile radio device, communicates with other mobile radio devices. Problem is prevented.

From the same problem, even if a mobile radio device is a fixed radio device on the downstream side, and a mobile radio device is a fixed radio device on the upstream side to another mobile radio device at the same time, the radio signal of the fixed radio device Degradation in strength should be prohibited.

Moreover, this invention may be grasped | ascertained as a radio signal transmission system control apparatus applied to the above-mentioned radio signal transmission system.

According to the present invention, there is provided a normal traffic system such as a base station (fixed radio device) capable of adjusting the signal strength used for radio signal transmission, and a discriminating mechanism for determining the position and direction of movement of the control device or the moving object (mobile radio device) It is possible to obtain a handover of the mobile radio apparatus appropriately only by making inexpensive facility changes for the configuration that should have, and obtain a good communication state between the mobile radio apparatus and the fixed radio apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring an accompanying drawing, and it contributes to understanding of this invention. In addition, the following embodiment is an example which actualized this invention, and is not a thing which limits the technical scope of this invention.

(1) About the structure of the wireless signal transmission system which concerns on this invention.

3 is a schematic structural diagram of a wireless signal transmission system according to the present invention. Hereinafter, the basic configuration of the wireless signal transmission system of the present invention will be described with reference to FIG.

As shown in Fig. 3, the vehicle 2 is traveling along a route 1 laid along a predetermined track. The vehicle 2 is equipped with a track 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 vehicle 2 while traveling via the local station 2a. The base stations 3a, 3b, 3c ... are connected to the radio signal transmission system control device 5 via the control command transmission line 4. The radio signal transmission system control device 5 controls each of the various base stations 3a, 3b, 3c ... including adjustment of radio signal strength used for communication with the vehicle 2.

Each of the base stations 3a, 3b, 3c, ... has a finite (usually several hundred m) communication area 6 that enables good communication, and the communication area 6 includes the base station 3a, 3b, 3c ...) are widened centering on each. In the base stations 3a, 3b, 3c, each of the communication areas 6 covers all of the lines 1, and the communication areas 6 in two adjacent base stations are the lines 1; ) So that they overlap slightly.

Here, an area (hereinafter referred to as a sole radio transmission area) in which only one base station (the base stations 3a, 3b, and 3c) can communicate on the route 1, and the communication area 6 of two base stations. The superimposed and alternately formed areas (hereinafter, redundant radio transmission areas) in which one of the two base stations can communicate with each other are formed.

With the movement of the vehicle 2, the base station to which wireless communication via the local station 2a (connected) switches in turn (i.e., handovers). Handover occurs in the redundant radio transmission area. For example, the vehicle 2 which is traveling in a single radio transmission area in the communication area 6 by the base station 3a is wirelessly connected to the station 2a and the base station 3a. Communication is possible. By the movement of the vehicle 2, the local station 2a reaches the redundant radio transmission area by the communication area 6 of the base station 3a and the communication area 6 of the base station 3b. In one case, the connection destination of the station 2a hands over from the base station 3a to the base station 3b while moving the redundant radio transmission area.

The local station 2a receives a radio signal by the local station 2a and performs various processes (data processing other than the radio communication itself usually installed in a wireless device such as communication protocol processing). It is connected to the signal processing apparatus 2b which performs switching control of a connection base station based on the wireless signal.

Next, with reference to FIG. 3, the difference in structure between the radio | wireless signal transmission system which concerns on this invention, and the radio | wireless signal transmission system in a prior art example is demonstrated. Here, since the basic configuration of the wireless signal transmission system of the present invention is the same as that of the conventional example in Fig. 1, the same reference numerals are used for the common components in the description of the conventional example.

A general railroad (an example of a transportation system) as shown in Fig. 3 is provided with the following configuration for determining the position of each vehicle on the route and the direction of movement thereof. The route 1 is a route on which the vehicle 2 travels. The leaky coaxial cable 7 is provided in parallel with the line 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 provided with the following vehicle position detection device. That is, the vehicle position detecting device transmits the information of the traveling distance and the driving direction of the vehicle measured from the rotation speed of the wheel and the like to the rewire detecting device 8 through the leaky coaxial cable 7. As a result, the rewire detection device 8 can detect the position of the vehicle 2 and the direction of movement.

In addition, the position detection of the said vehicle 2 may be performed using the said leaky coaxial cable 7 as follows.

Radio waves are radiated from the leaky coaxial cable 7 over their entire length, and part of the radio waves are radiated by the vehicle 2. This radiation propagation is re-received by the leaky coaxial cable 7. Moreover, the said radiation wave is input by the rewire detection apparatus 8 connected to the said leaky coaxial cable 7, and the position and the direction of the movement of the vehicle 2 are changed by the rewire detection apparatus 8 by this. It may be detected.

By the way, the radio signal transmission system A which concerns on embodiment of this invention shown in FIG. 3 has the mark 2a mounted in the said vehicle 2 which moves on the said route 1 (predetermined movement path). An example of a mobile radio device is a system for wireless communication (signal transmission in both directions) with a plurality of base stations 3a, 3b, 3c ... arranged along the line 1. In the radio receiving transmission system A, when the local station 2a receives radio signals from two or more of the plurality of base stations 3a, 3b, 3c ..., based on a comparison of the strengths of those radio signals To select (switch) any one of the base stations 3a, 3b, 3c, etc. as a signal transmission partner. Specifically, when the relative strength of the radio signals from the two base stations is greater than 15 dB, the signal processing apparatus 2b connected to the slave station 2a indicates that the greater of the signal strengths among the two base stations is indicated. It connects to it as a partner of radio signal transmission with the local station 2a. The radio signal transmission system control device 5 'according to the present invention is a control device for controlling the radio signal transmission system A. Specifically, a CPU of an operation unit, a storage unit for storing various kinds of information, and And an I / 0 unit which outputs a control instruction for signal strength adjustment to the base stations 3a, 3b, 3c ....

The rewire detection device 8 is connected to a control command transmission line 4 connecting the wireless signal transmission system control device 5 'and the base stations 3a, 3b, 3c ... via a communication cable 9. It is. As a result, the vehicle information list described later by the rewire 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) About the outline of the radio signal transmission system control apparatus which concerns on embodiment of this invention.

As described in the description of the conventional example, when the vehicle has one station, the strength of the radio transmission signal of the next base station is increased so that the base station that is currently the target of communication is switched (handed over) to the next base station. It is necessary to clearly exceed the strength (for example, 15 dB or more) of the radio transmission signal of the base station to be currently communicated. Therefore, the present invention is characterized in that a quick and reliable handover is promoted by adjusting the strength of the radio signal of each of the base stations with good timing without any change on the vehicle side.

First of all, the CPU (an example of the movement status detecting means) of the radio signal transmission system 5 'uses the information input from the re-wire detection device 8 used in the general railway as described above. The vehicle 2 and the station 2a (mobile radio device) mounted thereon are downstream with the base station (fixed radio device) adjacent to the upstream side of the base stations 3a, 3b, 3c in the movement direction thereof. Any one with the base station on the side has reached (detected) that it has reached the redundant radio transmission region where radio signal transmission is possible and its movement direction.

On the basis of such a determination result, when it is detected that the local station 2a (mobile radio apparatus) has reached the redundant radio transmission region in accordance with the processing procedure described later in detail, the downstream The signal strength of each base station that lowers the relative strength of the radio signal of the upstream base station to the base station (fixed radio device) on the side is set, and each of the base stations 3a, 3b, 3c ... is controlled in accordance with the setting. do. The I / O unit which outputs a control command to the base stations 3a, 3b, 3c ... in accordance with the CPU and the setting for setting the signal strength is an example of signal strength adjusting means.

Various settings are conceivable for lowering the relative strength of the radio signal of the upstream base station with respect to the downstream base station, but in this embodiment, the strength of the radio signal of the base station (fixed radio device) of the upstream side is lowered. In addition, the method of adjusting the signal strength for raising the radio signal on the downstream side is adopted.

(3) About the adjustment process of the radio signal strength in the case where a plurality of vehicles exist.

On the other hand, when there are a plurality of vehicles 2, for example, when such vehicles 2 are displaced, one of the base stations 3a, 3b, 3c. Communication with (2a) may be performed. 4 and 5 are schematic configuration diagrams in the case where a plurality of vehicles exist as such. As shown in Fig. 4, the vehicle 2 has reached a redundant radio transmission area where the communication area 6 by the base station 3a and the base station 3b overlaps. The base station 3a is in communication with a vehicle 2 'that is separate from the vehicle 2. In order to reliably hand over the vehicle 2, it is preferable to lower the strength of the radio signal of the base station 3a, but if it does so, the transmission of the radio signal with the vehicle 2 'stops. In this case, therefore, the control for lowering the signal strength of the base station 3a is prohibited.

That is, in the case where a plurality of the local stations 2a (mobile radio apparatus) can exist, the vehicle 2 is downstream from the base station 3a on the upstream side by the CPU (an example of the mobile situation detecting means). In the case where it has been detected that the redundant radio transmission area by the base station 3b on the side has been detected, the CPU (single area presence detecting means) still uses the information input from the re-wire detection device 8, It is discriminated (detected) whether or not another vehicle 2 'is present in a single radio transmission area capable of radio signal transmission only by the upstream base station 3a.

The CPU base station 3a (fixed) 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 existence detection means). Wireless device), the signal strength of each base station is set so as to prevent the radio signal strength from decreasing. According to the CPU and the settings set by the CPU, the I / O section for outputting a control command to the base stations 3a, 3b, 3c ... is an example of first signal strength adjustment limiting means.

In addition, when a plurality of routes 1 are laid down as shown in FIG. 5, another vehicle 2 ″ runs behind the vehicle 2 substantially in parallel with the vehicle 2. In that case, as shown in Fig. 5, the vehicle 2 is reaching the overlapping radio transmission area by the base station 3b and the base station 3c, and the vehicle 2 " It is also conceivable to reach the redundant radio transmission area by the base station 3a and the base station 3c. At this time, the base station 3b (fixed radio device) is located downstream from the station 2a (mobile radio device) mounted on the vehicle 2 and is mounted on the vehicle 2 at the same time. The mark 2a is located upstream. Even in such a case, when the strength of the radio signal of the base station 3b is lowered, the transmission of the radio signal with the vehicle 2 "stops, so that the signal is prohibited to lower the radio signal of the base station 3b. Strength setting is performed An I / O section for outputting a control command to the base stations 3a, 3b, 3c, according to the CPU and the settings set by the CPU, is an example of the second signal strength adjustment limiting means.

(4) About various data structures.

6 is a data configuration diagram of a vehicle information list input from the rewire detection device 8 to the wireless signal transmission system control device 5 '. 7 is a data configuration diagram of the information of 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 rewire detection device 8 generates a vehicle information list indicating the position and the moving direction of each of the vehicles 2, and transmits it to the radio signal transmission system control device 5 '. As shown in Fig. 6, the vehicle information list corresponds to the identification information 101 of each of the vehicles 2, and the position coordinate information 102 and the movement direction information 103 for each vehicle.

Further, information (radio transmission area information) of the redundant radio transmission area and the single radio transmission area as shown in FIG. 7 is stored in the storage unit of the radio signal transmission system control device 5 '. As shown in Fig. 7, the base station information 202 is responsible for the radio transmission area information when the coordinate area is the single radio transmission area with respect to the coordinate information 201 on the route 1, On the other hand, if the coordinate region is the redundant radio transmission region, the set information of the rising base station information 203 and the falling base station information 204 corresponds to each other. In addition, "up" and "down" as referred to herein indicate a predetermined direction in the line 1, and have a meaning different from "upstream" and "downstream" in the moving direction of the vehicle 2.

As mentioned above, the said wireless signal transmission system control apparatus 5 'is the all-vehicle vehicle from the said vehicle information list input from the said rewire detection apparatus 8, and the said wireless transmission area information previously stored in the said storage part. (2) Generate area information for each vehicle, in each direction of movement and in the single radio transmission area by which base station or in the redundant radio transmission area by any two base stations.

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 'is the setting information of radio signal strength for each of the base stations 3a, 3b, 3c ... as shown in FIG. (Radio signal strength setting information) is set, and the strength of the radio signal of the base stations 3a, 3b, 3c ... is controlled based on the radio signal strength setting information.

As shown in Fig. 8, the radio signal strength setting information corresponds to the base station identification information 301, and the current signal strength information 302 and the next signal strength information 303 correspond to each other.

The current signal strength information 302 converts the strength of the current radio signal of each of the base stations 3a, 3b, 3c, etc. into three levels of intensity of "maximum level", "stop level" and "maximum level -10 dB". Information shown. On the other hand, the next signal strength information 303 is information indicating the strength of the radio signal set based on area information for each vehicle in three levels of intensity, and the current signal strength information 302 As the predetermined time passes, the contents of the next signal strength information 303 are updated.

"Maximum level" indicates a state in which the strength of the radio signal of the base station is sufficient for communication with the local station 2a. This means that a radio signal of the maximum strength capable of transmitting each of the base stations 3a, 3b, 3c… must be outputted, and sufficient for communication according to the surrounding environment of each of the base stations 3a, 3b, 3c…, etc. It is good to set the strength of the radio signal. On the other hand, "stop level" indicates a state in which the transmission of the radio signal is stopped, that is, a state in which the strength of the radio signal is set to approximately zero. In this way, the strength of the radio signal of each of the base stations 3a, 3b, 3c ... is not reduced only to the level of approximately zero, thereby being used in the twisted pair of the radio signal transmission system A. It is possible to suppress the influence on the wireless LAN system or the like as much as possible. It is also preferable from the viewpoint of energy saving that the strength of the radio signal is reduced to about zero.

In addition, the "maximum level -10 dB" is in a state where communication with the station 2a is possible, but the signal strength is lowered by 10 dB compared to the "maximum level" state. When the vehicle 2 is in the redundant radio transmission region, if the maximum level of -10 dB is set for the upstream base station and the maximum level is set for the downstream base station, the redundant radio transmission is performed. In the area, the strength of the radio signal by the downstream base station is increased and handover is performed quickly.

In addition, once the setting information is updated, the strength of the radio signal is not reduced from the "maximum level" to the "stop level", and "maximum level -10 dB" and "maximum level -10 dB" from "maximum level". From the "stop level", the radio signal is gradually lowered.

If the station 2a suddenly stops the radio signal from the base station to which the radio signal is currently transmitted, the station 2a cannot perform a strength comparison with the radio signal from the base station to be the signal transmission next time. It is likely to interfere with. However, as described above, such a problem is avoided by suddenly lowering the signal strength via the "maximum level -10 dB" without suddenly making the radio signal a "stop level."

(5) A processing procedure for setting wireless signal strength setting information.

Fig. 9 is a flowchart showing a procedure for adjusting radio signal strength of a base station by the radio signal transmission system control device according to the embodiment of the present invention. Hereinafter, with reference to FIG. 9, the procedure of setting the said wireless signal strength setting information by the said wireless signal transmission system control apparatus 5 'is demonstrated in detail. In addition, the process of each order (step) in the flowchart shown in FIG. 9 is the CPU, the said storage part, and the said I / O which the said wireless signal transmission system control apparatus 5 'has in detail as mentioned later. And so on. Here, S1, S2,. Indicates the number (step) of the process, and is executed from the process of step S1 at the start of the radio communication by the radio signal transmission system A or the like.

As the processing of step S1, the CPU generates area information for each vehicle based on the vehicle information list input from the rewire detection device 8 and the wireless transmission area information stored in the storage unit.

As the processing of step S2 subsequent to step S1, the CPU sets the next signal strength information 303 in the wireless signal strength setting information once for all of the base stations 3a, 3b, 3c. Set to "."

Subsequent processes of steps S3 to S9 are sequentially performed for all the vehicles described in the vehicle information list.

In step S3 subsequent to step S2, the CPU can determine whether the vehicle 2 is located in the single radio transmission area. If it is determined that it is located in the single radio transmission area (YES in S3), the flow proceeds to step S5. On the other hand, if it is determined that it is not located in the single radio transmission area (NO in S3), the flow proceeds to step S4.

In step S5, in step S3 of the base stations 3a, 3b, 3c ..., the next signal strength of the base station corresponding to the single radio transmission region determined that the vehicle 2 is located is determined by the CPU. Maximum level ”. When step S5 is complete | finished, it progresses to step S9.

In step S4, the CPU can determine whether the vehicle 2 is located in the redundant radio transmission area. If it is determined that it is located in the redundant radio transmission area (YES in S3), the flow proceeds to step S6. On the other hand, if it is determined that it is not located in the redundant radio transmission area (NO in S4), the flow proceeds to step S9.

In step S6, the movement direction information 103 of the vehicle 2 is referred to, and the base station on the downstream side and the base station on the upstream side are determined for the two base stations corresponding to the redundant radio transmission area. Further, 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 the base station of the new connection destination of the vehicle 2 (preferably the local station 2a). When the process of step S6 is complete | finished, it progresses to step S7.

In the process of step S7, is the next signal strength already set to the "maximum level" for the upstream base station (that is, the base station corresponding to the single radio transmission area in which the separate vehicle is located or the base station on the downstream side); ) Can be determined. If it is already set to the "maximum level" (YES in S7), it is determined that the radio signal transmission is being carried out with another vehicle or to be the target of radio signal transmission of the other vehicle at the next time (i.e., FIG. 4, It is determined that it is the state shown in FIG. 5), and setting change is not made, and it progresses to step S9.

On the other hand, when it is not set to "maximum level" (it is set to "stop level") (NO of S7), it progresses to step S8. In step S8, the next signal strength is set to "maximum level -10 dB" by the CPU. In this way, the intensity of the radio signal is not suddenly set to the "stop level" for the upstream fixed radio device, and is set to "maximum level -10 dB" for the purpose of gradually decreasing the strength of the radio signal. do. In addition, after the vehicle 2 passes the overlapping radio transmission region, the strength of the radio signal is lowered to the "stop level" by the above-described process of step S2 (strictly, "Stop in step S2"). Signal strength information 303 set to &quot; level &quot; When the process of step S8 ends, it progresses to step S9.

In step S9, it is determined by the CPU whether or not the loop processing of steps S3 to S9 is finished for all the vehicles described in the vehicle information list. If it is determined that it is finished (YES in S9), the flow proceeds to step S10. On the other hand, in the case where it is determined that the loop processing has not been completed for all vehicles (NO in S9), the process returns to step S3.

In step S10 subsequent to step S9, the next signal strength information set by the loop processing of steps S3 to S9 is set as the new current signal strength. Further, control commands for each of the base stations 3a, 3b, 3c ... based on the new current signal strength are output through the I / O unit.

In the above-described embodiment, the railroad is taken as an example of a traffic system. However, the present invention can be applied to a wireless signal transmission system with a vehicle in a traffic system using a linear motor car and a traffic system using a monorail.

Further, in the above-described embodiment, the radio communication is performed between the base station and the local station. However, in the so-called broadcast mode, one of the local 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 signal transmission is performed.

According to the present invention, a radio signal transmission system control capable of enabling handover at an appropriate point as cheaply as possible without making a large change to a device on the mobile side such as a vehicle, thereby maintaining a good communication state An apparatus and a wireless signal transmission system having the same can be provided.

Claims (8)

Wireless signal transmission system, A mobile wireless device moving on a predetermined movement path, A fixed wireless device for transmitting radio signals in one or both directions between the mobile wireless devices arranged in plural along the moving paths; A wireless signal transmission system for controlling switching of the fixed wireless device to be a signal transmission based on a comparison of the strengths of the wireless signals when the mobile wireless device receives the wireless signals from the plurality of fixed wireless devices; Consisting of a control unit, Wherein the strength of the radio signal emitted by the fixed radio device to the mobile radio device is variable, Here, the wireless signal transmission system control device, The mobile radio apparatus has reached a redundant radio transmission region in which any of 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 can transmit radio signals; and Moving situation detecting means for detecting a moving direction; When it is detected by the movement state detecting means that the mobile radio apparatus has reached the redundant radio transmission region, the relative strength of the radio signal of the upstream fixed radio apparatus with respect to the downstream fixed radio apparatus is lowered. Wireless signal transmission system comprising a signal strength adjustment means. The radio signal transmission system according to claim 1, wherein said signal intensity adjusting means lowers the strength of a radio signal of said fixed radio device on the upstream side. The radio signal transmission system according to claim 2, wherein said signal intensity adjusting means gradually lowers the intensity of a radio signal of said upstream fixed radio device. The radio signal transmission according to claim 2, wherein said signal strength adjusting means decreases the strength of a radio signal of said upstream fixed side wireless device and increases the strength of a radio signal of said downstream fixed wireless device. system. The wireless signal transmission system according to claim 2, wherein said signal strength adjusting means reduces the strength of a radio signal of said upstream fixed wireless device to approximately zero. The upstream fixing according to claim 1, further comprising a case in which a plurality of said mobile radio apparatuses can exist, wherein said upstream side corresponding to said redundant radio transmission region in which arrival of said mobile radio apparatus by said movement condition detecting means is detected. A single area presence detecting means for detecting whether or not the other mobile radio device exists in a single wireless transmission area capable of transmitting a wireless signal only by the fixed wireless device, for a wireless device; Means for prohibiting the wireless signal strength from being lowered by the signal strength adjusting means for the fixed wireless device corresponding to the single wireless transmission area in which the presence of the other mobile wireless device is detected by the single area existence detecting means. A radio signal transmission system comprising a signal strength adjustment limiting means. The mobile station according to claim 1, wherein when there are a plurality of the mobile radio apparatuses, the mobile radio apparatus serves as the downstream fixed radio apparatus for the mobile radio apparatus according to the detection situation of the mobile situation detecting means. A wireless signal transmission system comprising a second signal strength adjustment limiting means for prohibiting the wireless signal strength from being lowered by the signal strength adjusting means with respect to the fixed wireless device which is the upstream fixed wireless device for the mobile radio device. . An apparatus for controlling a radio signal transmission system used for the radio signal transmission system according to claim 1.

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