JP4097254B2 - Wireless network system, mobile station, and mobile station control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the influence on the functions of the entire mobile object positioning system by complementing the omission of position information even in the case that highly accurate position information can not be acquired in a mobile station. <P>SOLUTION: In the case that a GPS positioning becomes impossible or the accuracy of GPS positioning declines in the mobile stations 13-1 to 13-3, a control station 11 adds transmission time data equivalent to the transmission time of the broadcast for each of base stations 12-1 to 12-3 to a broadcast message. The base stations 12-1 to 12-3 transmit the broadcast message to which the transmission time data are added to the mobile stations 13-1 to 13-3. Thus, in the case that the GPS positioning is impossible or the accuracy of GPS positioning declines, the mobile stations 13-1 to 13-3 calculate their own positions on the basis of the transmission time data. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio network system, a mobile station, and a mobile station control method, and more particularly to a self-position measurement technique for a mobile station.
[0002]
[Prior art]
Conventionally, a mobile station performs DGPS (Differencial Global Positioning System) positioning using correction data from a base station to realize highly accurate positioning.
[0003]
Position information data corresponding to the position information of the measured mobile station is accumulated and managed in the control station via the base station (see, for example, Patent Document 1).
[0004]
In the control station and the mobile station, the position and movement locus of each mobile station are displayed on the display on the map screen based on the position information data.
[0005]
A conventional mobile positioning system is roughly divided into a control station, a base station, and a mobile station.
[0006]
The control station has a display device for performing a useful management of all base stations and realizing a function of displaying the position of each mobile station.
[0007]
The base station is connected to the control station via a wired network, and is connected to the base station via a wireless network. The base station then distributes correction data for performing DGPS positioning to mobile stations belonging to the corresponding service area via the wireless network, or notifies the control station of positioning information from the mobile station via the wired network. It has the function of
[0008]
The mobile station performs DGPS positioning in its own GPS receiver using the correction data from the base station, and acquires positioning information.
[0009]
In the above-described conventional mobile positioning system, the position information data of the measured mobile station is accumulated and managed in the control station via the base station.
[0010]
Based on the obtained position information data, the position of each mobile station and the movement trajectory (for example, the travel trajectory of the vehicle) are displayed on the map in the display device of the control station and the display device of the mobile station. It was.
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-355315
[Problems to be solved by the invention]
However, if the mobile station cannot receive GPS radio waves from GPS satellites, such as when it is located behind a building, positioning of the mobile station becomes impossible. When the mobile positioning system is used for vehicle management or the like, there is a problem that the influence is great.
[0013]
Therefore, an object of the present invention is to provide wireless that can compensate for the lack of position information and reduce the influence on the functions of the entire mobile positioning system even when accurate position information cannot be acquired in a mobile station. To provide a network system, a mobile station, and a mobile station control method.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, a wireless network system is capable of GPS positioning, and a plurality of mobile stations capable of calculating their own position based on transmission time data, and the mobile station by radio using a predetermined radio protocol. A plurality of base stations each having a service area for performing communication, transmitting a broadcast message to the mobile station, a wired network connected to the base station, connected to the wired network, the mobile station and A control station that manages the base station, and in the mobile station, when the GPS positioning is disabled or the accuracy of the GPS positioning is reduced, the corresponding mobile station passes through the base station to the control station. Means to notify that positioning is impossible or that positioning accuracy has deteriorated, and if there is a notification to this control station And means for adding the transmission time data corresponding to the transmission time of the broadcast to the broadcast message of the base stations that provide a coverage area of the serving mobile station for which the positioning accuracy decreases, and
Based on the transmission time data, a mobile station that has not been able to perform positioning or has lost positioning accuracy can calculate its own position and notify the control station of its own position.
It is characterized by that.
[0015]
According to the above configuration, in the mobile station, when the GPS positioning is disabled or the accuracy of the GPS positioning is lowered, the corresponding mobile station notifies the control station of the positioning impossible or the positioning accuracy lowered via the base station. To do.
As a result, the control station transmits the transmission time corresponding to the transmission time of the broadcast to the broadcast message of the base station that provides the service area in which the mobile station where the mobile station where positioning is impossible or the positioning accuracy is degraded when this notification is given. Add data.
[0016]
The base station transmits a broadcast message added with transmission time data to the mobile station.
[0017]
As a result, the mobile station that cannot be positioned or has degraded positioning accuracy calculates its own position based on the transmission time data and notifies the control station of its own position. Even if it exists, it is possible to reliably notify the control station of its own position.
[0018]
In this case, the GPS positioning is performed by the DGPS positioning method, and the broadcast message may include correction data used for the DGPS positioning method.
[0019]
Further, the mobile station calculates the self position based on a difference between a transmission time of the broadcast message corresponding to the transmission time data from a plurality of the base stations and an actual reception time of the broadcast message. You may do it.
[0020]
Furthermore, hyperbolic navigation may be used when calculating the self-position.
[0021]
A GPS receiver that performs GPS positioning, a positioning state detection unit that detects that the GPS positioning is disabled or the accuracy of the GPS positioning is reduced, and the GPS positioning is disabled or the accuracy of the GPS positioning. Is notified to the control station via an external base station, and the transmission time data corresponding to the transmission time of the broadcast message transmitted from the base station is added along with the notification. The broadcast message is received, and the self-position is calculated based on the difference between the broadcast message transmission time corresponding to the transmission time data from the plurality of base stations and the actual reception time of the broadcast message. The self-position calculation unit and the calculated self-position are notified to the control station via the base station. It is characterized with self position notification unit, further comprising a that.
[0022]
According to the above configuration, the positioning state detection unit detects that the GPS positioning is disabled or the accuracy of the GPS positioning is lowered.
As a result, the notification unit notifies the control station via the external base station that GPS positioning has become impossible or the accuracy of GPS positioning has deteriorated.
On the other hand, the self-position calculation unit receives a broadcast message to which transmission time data corresponding to the transmission time of the broadcast message transmitted from the base station is added in accordance with this notification, and transmits transmission time data from a plurality of base stations. The self-position is calculated based on the difference between the transmission time of the broadcast message corresponding to and the actual reception time of the broadcast message.
As a result, the self-position notifying unit notifies the calculated self-position to the control station via the base station.
[0023]
The notification unit notifies the control station via an external base station that GPS positioning has become impossible or the accuracy of GPS positioning has deteriorated.
[0024]
When the GPS positioning is disabled or the accuracy of the GPS positioning is reduced, the self-position calculating unit sends a broadcast message in which the transmission time data corresponding to the transmission time of the broadcast for each base station is added from the base station. The self-position is calculated based on the difference between the transmission time of the broadcast message corresponding to the transmission time data from a plurality of base stations and the actual reception time of the broadcast message.
[0025]
In this case, hyperbolic navigation may be used when calculating the self-position.
[0026]
Further, in a control method of a mobile station equipped with a GPS receiver for performing GPS positioning, a positioning state detection process for detecting that the GPS positioning is disabled or the accuracy of the GPS positioning is reduced, and the GPS positioning is disabled. A notification process for notifying the control station via the base station that the GPS positioning has been reduced or the accuracy of the GPS positioning is reduced, and the transmission corresponding to the transmission time of the broadcast message transmitted from the base station along with the notification Receiving a broadcast message to which time data is added, and based on a difference between a transmission time of the broadcast message corresponding to the transmission time data from a plurality of the base stations and an actual reception time of the broadcast message The self-position calculation process for calculating the self-position and the calculated self-position A self position notification process of notifying the control station via the Chikyoku, is characterized by comprising a.
[0027]
In this case, hyperbolic navigation may be used when calculating the self-position.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to the drawings.
[0029]
FIG. 1 is a schematic configuration diagram of a mobile body positioning system according to an embodiment.
[0030]
The mobile body positioning system 10 includes a control station 11, base stations 12-1 to 12-3, and mobile stations 13-1 to 13-3, when roughly classified. In FIG. 1, each of the base stations 12-1 to 12-3 and the mobile stations 13-1 to 13-3 has a one-to-one correspondence. It is possible to correspond to any mobile station.
[0031]
The control station 11 manages the entire mobile positioning system 10 and has a display device for performing operation management of all base stations and realizing a function of displaying the position of each mobile station. .
[0032]
FIG. 2 is a block diagram showing a configuration example of the data communication device in the control station.
[0033]
In FIG. 2, the data communication device 51 includes a wired network communication unit 52, a memory unit 53, and a control unit 54.
[0034]
The wired network communication unit 52 communicates with the wired LAN 27.
[0035]
The memory unit 53 stores and relays data of the wired network communication unit 52.
[0036]
The control unit 54 controls the wired network communication unit 52 and the memory unit 53 and relays data according to a predetermined protocol.
[0037]
As shown in FIG. 1, the control station 11 is connected to the same network as the base stations 12-1 to 12-3 by a wired LAN 14, and is connected to each base station 12-1 to 12-3 and the wired LAN 27. By exchanging control packets, the management operations of the base stations 12-1 to 12-3 and the mobile stations 13-1 to 13-3 are realized.
[0038]
The base stations 12-1 to 12-3 are connected to the control station 11 via a wired network, and are connected to the base station via a wireless network. Then, the base station distributes correction data for performing DGPS positioning to the mobile stations belonging to the corresponding service areas SA1 to SA3 via the wireless network, or receives the positioning information from the mobile station via the wired network. It has a function to notify. In FIG. 1, service areas SA1 to SA3 are not synonymous with radio communication areas in the respective base stations 12-1 to 12-3, and an effective radio communication area is stopped due to a failure of one of the base stations. Even if it is a case, it is comprised so that the other base station can cover the service area of the base station which has stopped. That is, the wireless communication area is configured to include the service area.
[0039]
Accordingly, each of the mobile stations 13-1 to 13-3 can receive radio waves from the adjacent base stations 12-1 to 12-3 in any of the service areas SA1 to SA3.
[0040]
FIG. 3 is a block diagram showing a configuration example of the SS communication device in the base station 12-1. The base stations 12-1 to 12-3 have the same configuration.
[0041]
In FIG. 3, this SS communication device roughly includes a wired communication unit 31, an SS wireless communication unit 32, a memory unit 33, and a control unit 34.
[0042]
The wired communication unit 31 communicates with the wired LAN 27. For example, it is represented by Ethernet.
[0043]
The SS wireless communication unit 32 manages SS modulation / demodulation.
[0044]
The memory unit 33 stores and relays data between the wired communication unit 31 and the SS wireless communication unit 32.
[0045]
The control unit 34 controls the wired communication unit 31, the SS wireless communication unit 32, and the memory unit 33, and relays data according to a predetermined procedure (protocol).
[0046]
FIG. 4 is a block diagram showing a configuration example of the SS communication device in the mobile station 13-1. The mobile stations 13-1 to 13-3 have the same configuration.
[0047]
In FIG. 4, the mobile station 13-1 has an SS communication device 41 that wirelessly exchanges data with the SS communication devices on the base stations 12-1 and 12-2 side, and a GPS antenna 46. On the other hand, a GPS side device 45 connected using a serial system such as RS-232C is provided.
[0048]
The SS communication device 41 includes an SS wireless communication unit 42, a memory unit 43, and a control unit 44.
[0049]
The SS wireless communication unit 42 performs SS demodulation / modulation. As a matter of course, the SS modulation and SS demodulation methods of the radio communication unit 32 of the base stations 21 and 22 and the SS radio communication unit 42 of the terminal station must be the same.
[0050]
The memory unit 43 stores / relays data of the SS wireless communication unit 42.
[0051]
The control unit 44 controls the SS wireless communication unit 42 and the memory unit 43, and relays data according to a predetermined protocol.
[0052]
FIG. 5 is an operation sequence chart.
[0053]
Each of the base stations 12-1 to 12-3 distributes data common to all the mobile stations 13-1 to 13-3 by broadcasting based on a polling communication protocol.
[0054]
Thereafter, the mobile station belonging to the service area corresponding to the base station performs polling and transmission / reception of various data including position information data independently for each mobile station.
[0055]
In this case, the broadcast is collectively managed by the control station 11, and each of the mobile stations 13-1 to 13-3 receives a plurality of broadcast messages from a plurality of base stations corresponding to the service area to which the mobile station 13-1 belongs. Will be.
[0056]
Specifically, the broadcast of the base station 12-1 is transmitted at the reference time t1 under the control of the control station 11. For example, the mobile station 13-1 The broadcast message is received when the time Δ1 has elapsed from the reference time t1 according to the distance to 12-1.
[0057]
Similarly, the broadcast of the base station 12-2 is transmitted at the reference time t2 under the control of the control station 11. For example, the mobile station 13-1 is connected to the mobile station 13-1 and the base station 12-2. The broadcast message is received when the time Δ2 has elapsed from the reference time t2.
[0058]
Further, the broadcast of the base station 12-3 is transmitted at the reference time t3 under the control of the control station 11. For example, the mobile station 13-1 is connected to the mobile station 13-1 and the base station 12-3. Depending on the distance, a broadcast message is received when time Δ3 has elapsed from the reference time t3.
[0059]
In the normal operation mode (normal mode), each of the mobile stations 13-1 to 13-3 performs DGPS positioning using the correction data distributed by broadcast from the base stations 12-1 to 12-3.
[0060]
Each of the mobile stations 13-1 to 13-3 cannot perform GPS positioning when it cannot receive any GPS radio waves from GPS satellites or cannot receive GPS radio waves from the number of GPS satellites necessary for high-accuracy positioning. Alternatively, since the accuracy is lowered, the positioning state deterioration information for notifying the positioning stop or the positioning accuracy deterioration is notified to the base station corresponding to the service area to which the self belongs. This positioning state deterioration information is notified to the control station 11 via the base stations 12-1 to 12-3.
[0061]
FIG. 6 shows a state transition diagram of the mobile positioning system.
[0062]
When the positioning state deterioration information is notified, the control station 11 causes the mobile body positioning system 10 to transition from the normal mode ST1 in which high-precision positioning is performed to the abnormal mode ST2 in which low-precision positioning is performed by performing a transition process TR1. .
[0063]
When the mobile positioning system 10 transitions to the abnormal mode, the base station 12-1 to 12-3 receives a broadcast message distributed from the base stations 12-1 to 12-3 under the control of the control station 11. In the base stations 12-1 to 12-3, the broadcast message transmission start time is embedded.
[0064]
In this case, since the broadcast message before the broadcast message transmission start time is embedded in each of the base stations 12-1 to 12-3 is common and includes GPS correction data, the base station that transmits the message Each mobile station 13-1 to 13-3 receives a message in a state where different transmission start time data is added for each station.
[0065]
That is, each mobile station 13-1 to 13-3 receives the broadcast message, thereby receiving the GPS correction data and the transmission start time data corresponding to the base station that transmitted the message.
[0066]
Accordingly, each of the mobile stations 13-1 to 13-3 calculates the above-described time difference Δ1 to Δ3 based on the transmission start time data and the time when the broadcast message is actually received.
[0067]
Each of the mobile stations 13-1 to 13-3 determines the position by, for example, hyperbolic navigation based on the position coordinate data of each of the base stations 12-1 to 12-3 and the calculated time differences Δ1 to Δ3. By using the technique, the current position coordinates P of the mobile station are calculated as shown in FIG. The current position coordinates P calculated in this way are low in accuracy, but can be sufficiently practically accurate as long as they are within a time range in which the error accumulation does not become very large.
[0068]
Therefore, the current position of the mobile station can be displayed in a simple manner on the display screen of the display station of the control station 11 or on the display screen of the display apparatus mounted on each mobile station, and the service can be continued.
[0069]
Thereafter, when each mobile station 13-1 to 13-3 is in a state where it can completely receive GPS radio waves from GPS satellites or a state where it can receive GPS radio waves from the number of GPS satellites necessary for high-accuracy positioning, GPS positioning is performed. Therefore, the notification of the positioning state deterioration information is interrupted to notify the positioning restart.
[0070]
The interruption of the notification of the positioning state deterioration information is notified to the control station 11 via the base stations 12-1 to 12-3.
[0071]
As a result, the control station 11 causes the mobile body positioning system 10 to transition from the abnormal mode ST2 in which the low-precision positioning is performed to the normal mode ST1 in which the high-precision positioning is performed by performing the transition process TR2.
[0072]
Thus, in the broadcast message distributed from the base stations 12-1 to 12-3 under the control of the control station 11, the base stations 12-1 to 12-3 in the base stations 12-1 to 12-3. The mobile station 13-1 to 13-3 again uses the correction data distributed by broadcast from the base stations 12-1 to 12-3 using the correction data distributed by the DGPS. Positioning will be performed.
[0073]
As described above, in the normal mode ST1, since the broadcast message distributed from each of the base stations 12-1 to 12-3 does not include the transmission start time data, the transmission period of the broadcast message in the normal mode ST1. The transmission start time data is not required to be incorporated, and the load on the mobile positioning system 10 can be reduced.
[0074]
In the above description, in order to effectively use the limited communication band, the system switches the mode between the normal mode ST1 and the abnormal mode ST2. However, a sufficient communication band is required under a high-speed data link system. When the width can be used, it is possible to configure so that both modes can be arbitrarily selected without switching the mode.
[0075]
As described above, according to the present embodiment, even in an environment in which GPS radio waves from GPS satellites cannot be received, such as when a mobile station has entered the shadow of a building, the accuracy is low. Positioning can be continued, which can contribute to improving the reliability of the entire system.
[0076]
【The invention's effect】
According to the present invention, GPS positioning is disabled or the accuracy of GPS positioning is reduced in an environment in which GPS radio waves from GPS satellites cannot be received, such as when a mobile station is in the shadow of a building. Even in this case, the control station is notified of the fact via the base station, and under the control of the control station, the base station transmits the transmission time data to the mobile station in which the PS positioning is disabled or the GPS positioning accuracy is reduced. Since the mobile station can transmit the mobile station to the control station with low accuracy based on the transmission time data, the control station can manage the mobile station without being affected by GPS positioning. This can contribute to improving the reliability of the whole body positioning system.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a mobile body positioning system according to the present invention.
FIG. 2 is a schematic configuration block diagram of a control station.
FIG. 3 is a schematic configuration block diagram of a base station.
FIG. 4 is a schematic configuration block diagram of a mobile station.
FIG. 5 is an operation timing chart during broadcasting.
FIG. 6 is an operation mode transition diagram.
FIG. 7 is an explanatory diagram of a mobile station position calculation method.
[Explanation of symbols]
FIG.
10 Mobile positioning system 11 Control stations 12-1 to 12-3 Base stations 13-1 to 13-3 Mobile station 14 Wired LAN

Claims (8)

A plurality of mobile stations capable of GPS positioning and capable of calculating their own position based on transmission time data;
A plurality of base stations each having a service area for communicating with the mobile station by radio using a predetermined radio protocol, and transmitting a broadcast message to the mobile station;
A wired network to which the base station is connected;
A control station connected to the wired network and managing the mobile station and the base station ;
In the mobile station, when the GPS positioning is disabled or the accuracy of the GPS positioning is reduced, the corresponding mobile station notifies the control station that the positioning is impossible or the positioning accuracy is reduced via the base station;
The transmission time data corresponding to the positioning impossible or transmission time of the broadcast to the broadcast message of the base stations that provide a coverage area of the serving mobile station for which the positioning accuracy decreases when there is a notification to the control station Means for adding
With
Based on the transmission time data, a mobile station that has not been able to perform positioning or has lost positioning accuracy can calculate its own position and notify the control station of its own position.
A wireless network system characterized by the above. The wireless network system according to claim 1,
The GPS positioning is performed by the DGPS positioning method,
The wireless network system, wherein the broadcast message includes correction data used for the DGPS positioning method. The wireless network system according to claim 1 or 2,
The mobile station calculates the self-position based on a difference between a transmission time of the broadcast message corresponding to the transmission time data from a plurality of base stations and an actual reception time of the broadcast message. A featured wireless network system. The wireless network system according to claim 3, wherein
A radio network system using hyperbolic navigation when calculating the self-position. A GPS receiver that performs GPS positioning;
A positioning state detection unit for detecting that the GPS positioning is disabled or that the accuracy of the GPS positioning is reduced;
A notification unit for notifying the control station via an external base station that the GPS positioning is disabled or the accuracy of the GPS positioning is reduced;
Along with the notification, the broadcast message to which the transmission time data corresponding to the transmission time of the broadcast message transmitted from the base station is added is received, and the transmission time data from a plurality of the base stations is handled. A self-position calculating unit that calculates the self-position based on a difference between a transmission time of the broadcast message and an actual reception time of the broadcast message;
A self-position notifying unit for notifying the control station via the base station of the calculated self-position;
A mobile station characterized by comprising: The mobile station according to claim 5, wherein
A mobile station characterized by using hyperbolic navigation when calculating the self-position. In a control method of a mobile station equipped with a GPS receiver that performs GPS positioning,
A positioning state detection process for detecting that the GPS positioning is disabled or that the accuracy of the GPS positioning is reduced;
A notification process for notifying the control station via the base station that the GPS positioning is disabled or that the accuracy of the GPS positioning is reduced;
The broadcast message added with the transmission time data corresponding to the transmission time of the broadcast message transmitted from the base station with the notification is received, and the transmission time data corresponding to the transmission time data from the plurality of base stations is received. A self-position calculation step of calculating the self-position based on a difference between a broadcast message transmission time and an actual reception time of the broadcast message;
A self-location notification process in which the calculated self-location is notified to the control station via the base station;
A method for controlling a mobile station, comprising: The mobile station control method according to claim 7, wherein
A method for controlling a mobile station, wherein hyperbolic navigation is used when the self-position is calculated.

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