This application is a National Stage Entry of PCT/JP2019/047755 filed on Dec. 6, 2019, which claims priority from Japanese Patent Application 2019-002687 filed on Jan. 10, 2019, the contents of all of which are incorporated herein by reference, in their entirety.
The present invention relates to a technique of analyzing a presence situation of an obstacle that affects wireless communication.
In recent years, an information and communication technology (ICT) system utilizing a wireless network has been introduced to a construction site, a plant, and the like, for the purpose of improving productivity and improving safety. For example, when an operation state of production equipment is monitored via a wireless network by using a sensor, a problem such as a defect of the production equipment can be detected quickly. Alternatively, standby time, inefficient behavior, and the like during work are analyzed based on information on a position of a worker, which is acquired via a wireless network, whereby production efficiency can be improved.
In this way, introduction of an ICT system requires establishment of a wireless communication environment in most cases. However, a wireless communication environment (an environment in which a signal is transmitted) at a plant or the like frequently changes along with frequent change of a physical environment, and hence a problem of establishing a stable wireless communication environment arises. Further, there have been increasing expectations for a technique of achieving quick and accurate analysis of causes in a case of occurrence of a wireless communication failure, in order to solve such a problem.
As a technique relating to such a technique, PTL 1 discloses a failure cause determination device that determines a failure cause in a wireless link by acquiring a received signal strength indicator (RSSI) of the wireless link and a packet error rate (PER). The device estimates an RSSI-PER characteristic curve that passes through a point associated to a combination of an RSSI value and a PER value at a first time point that is a predetermined time period before a second time point when the PER becomes equal to or greater than a threshold value, assuming that interference power at the first time point is maintained. Further, the device determines whether a failure is caused by signal interference or deterioration of a signal transmission environment, based on a position relationship of a point associated to a combination of an RSSI value and a PER value at the second time point with respect to the estimated characteristic curve.
Further, PTL 2 discloses a wireless station that is connected to another wireless station via a wireless link and specifies a failure cause in the wireless link. The wireless station executes wireless link control for the wireless link, according to a wireless link control method. While executing the wireless link control, the wireless station acquires statistical information indicating a state of the wireless link. Then, based on the acquired statistical information, the wireless station specifies a failure cause in the wireless link, from among a plurality of failure causes that are associated with the statistical information in advance.
Further, PTL 3 discloses a wireless communication system that autonomously re-constructs a wireless communication path through evaluation of a wireless service area and automatic adjustment of a wireless parameter in a wireless communication environment where signal strength changes when a person or an object moves. A wireless station in the system measures signal strength of a received signal, and when fluctuation of a communication environment is detected by comparing the measured signal strength with past signal strength, the wireless station notifies a central server of the measurement value and the fluctuation generation. Based on the measurement value notified from the wireless station, the central server estimates a fluctuation position in the signal transmission path within the system and a cause, derives a wireless parameter suitable for fluctuation in the communication environment, and notifies the wireless station of the wireless parameter.
For example, at a site where an environment relating to the wireless communication as described above changes rapidly, it has been expected to establish a stable wireless communication environment more securely and efficiently. Further, in order that a suitable measure capable of improving a deteriorated wireless communication state is to be taken efficiently, there is a problem in analyzing a detailed cause for the deteriorated wireless communication state efficiently and with high accuracy, for example, analyzing whether the cause is attenuation of signal strength due to an obstacle present at a specific location, a long distance between a wireless terminal device and an access point being a communication destination, or the like. It cannot be said that PTLs 1 to 3 are sufficient to solve the problem. A main object of the present invention is to provide a wireless communication failure analysis device and the like that solve the problem.
A wireless communication failure analysis device according to one aspect of the present invention includes: an estimation means for estimating a movement locus of a communication terminal device communicable with an access point being installed at a known position, based on a measurement result indicating a communication state between the access point and the communication terminal device, which changes along with movement of the communication terminal device, and an estimation result relating to a presence situation of an obstacle that affects the communication state; a correction means for correcting the movement locus, based on restriction information indicating a restriction content relating to movement of the communication terminal device; a generation means for generating the estimation result, based on the movement locus that is corrected and the measurement result; and a control means for generating the restriction information in such a way as to gradually strengthen the restriction content until the restriction content satisfies a condition, and executing control in such a way that estimation of the movement locus by the estimation means, correction of the movement locus by the correction means based on the restriction information that is generated, and generation of the estimation result by the generation means are repeatedly performed.
In another view of achieving the above-mentioned object, a wireless communication failure analysis method according to one aspect of the present invention is executed by an information processing device, and includes: estimating a movement locus of a communication terminal device communicable with an access point being installed at a known position, based on a measurement result indicating a communication state between the access point and the communication terminal device, which changes along with movement of the communication terminal device, and an estimation result relating to a presence situation of an obstacle that affects the communication state; correcting the movement locus, based on restriction information indicating a restriction content relating to movement of the communication terminal device; generating the estimation result, based on the movement locus that is corrected and the measurement result; and generating the restriction information in such a way as to gradually strengthen the restriction content until the restriction content satisfies a condition, and executing control in such a way that estimation of the movement locus, correction of the movement locus based on the restriction information that is generated, and generation of the estimation result are repeatedly performed.
Further, in further view of achieving the above-mentioned object, a wireless communication failure analysis program according to one aspect of the present invention causes a computer to execute: estimation processing of estimating a movement locus of a communication terminal device communicable with an access point being installed at a known position, based on a measurement result indicating a communication state between the access point and the communication terminal device, which changes along with movement of the communication terminal device, and an estimation result relating to a presence situation of an obstacle that affects the communication state; correction processing of correcting the movement locus, based on restriction information indicating a restriction content relating to movement of the communication terminal device; generation processing of generating the estimation result, based on the movement locus that is corrected and the measurement result; and control processing of generating the restriction information in such a way as to gradually strengthen the restriction content until the restriction content satisfies a condition, and executing control in such a way that estimation of the movement locus in the estimation processing, correction of the movement locus in the correction processing based on the restriction information that is generated, and generation of the estimation result in the generation processing are repeatedly performed.
Further, the present invention may be achieved with a computer-readable non-volatile recording medium in which the wireless communication failure analysis program (computer program) is stored.
The present invention enables highly accurate and efficient analysis of a presence situation of an obstacle that affects a wireless communication state.
Now, with reference to the drawings, example embodiments of the present invention are described in detail.
For example, the communication terminal device 20 is a mobile terminal device such as a smartphone or a tablet that is carried by a user, and can be connected to a communication network via an access point (a device that relays wireless connection between the mobile terminal device and the communication network: hereinafter, referred to as “AP” in some cases in the present application). The communication terminal device 20 and the wireless communication failure analysis device 10 are connected to each other in a communicable manner via the communication network, by using a communication interface (not illustrated in
The communication terminal device 20 includes a communication state measurement unit 21. The communication state measurement unit 21 measures a communication state between the communication terminal device 20 and an access point (not illustrated in
The management terminal device 30 is an information processing device such as a personal computer, which is used when a user inputs information with respect to the wireless communication failure analysis device 10 or a user confirms information output from the wireless communication failure analysis device 10. The management terminal device 30 and the wireless communication failure analysis device 10 are connected to each other in a communicable manner via the communication network, by using a communication interface (not illustrated in
The wireless communication failure analysis device 10 is an information processing device that analyzes a presence situation of an obstacle that affects a wireless communication environment established in a certain target area.
The wireless communication failure analysis device 10 includes an estimation unit 11, a correction unit 12, a generation unit 13, a control unit 14, and a storage unit 15. For example, the storage unit 15 is a storage device such as an electronic memory or a magnetic disc. The storage unit 15 stores the measurement result 151, a signal transmission model 152, a movement locus 153, restriction information 154, a corrected movement locus 155, and an obstacle estimation result 156. Details of those pieces of information stored in the storage unit 15 are described later.
As exemplified in
Information provided to the wireless communication failure analysis device 10 includes the measurement result 151, a position (coordinate) of each access point, and the restriction information 154 indicating a restriction (limitation) content relating to movement of the communication terminal device 20, which is described later. Specifically, the wireless communication failure analysis device 10 has a function of deriving (estimating) a presence situation of an obstacle and an actual movement locus in which a user walks around the obstacle, based on the provided pieces of information, as described later.
According to the measurement result 151 exemplified in
The estimation unit 11 illustrated in
First, the estimation unit 11 uses the initial value of the obstacle estimation result 156 (specifically, assuming that no obstacle is present in the analysis target area), and calculates the signal transmission model 152 relating to wireless communication between each of AP1 to AP3 and the communication terminal device 20.
When it is assumed that no obstacle is present in the area, RSSI relating to a position Li (i is a freely-selected natural number) of the communication terminal device 20 and a position LAPk of the access point APk (k is an integer being any one of 1 to 3) in the analysis target area can be calculated by using Expression 1 and Expression 2.
RSSI(LAP
LOS(f,d)=20 log10f+N log10d−28 (Expression 2)
Note that, in Expression 1 and Expression 2, “LOS” indicates an estimation expression of a loss characteristic relating to signal transmission in an environment where no obstacle that affects the wireless communication state is present, and is given as in Expression 2 in line with International Telecommunication Union (ITU)-R Recommendations, for example. Further, in Expression 1 and Expression 2, f indicates a signal frequency of the wireless communication, d indicates a function for deriving a distance between one of AP1 to AP3 and the communication terminal device 20, and N indicates an attenuation coefficient. Further, log10 in Expression 2 indicates a logarithm (common logarithm) having 10 as a base.
Based on the calculated signal transmission model 152 and the measurement result 151, the estimation unit 11 can estimate a position of the communication terminal device 20 for each elapsed time after the communication terminal device 20 starts movement, by using, for example, the Finger Print method being a publicly known method or the like. By using the Finger Print method, the estimation unit 11 estimates a position of the communication terminal device 20 for each elapsed time after the communication terminal device 20 starts movement, as demonstrated in Expression 3, for example.
Note that, in Expression 3, m is a natural number indicating a chronological order relating to an elapsed time after the communication terminal device 20 starts movement (an order in which measurement is performed). Further, in the measurement result 151 exemplified in
Further, in Expression 3, argmin indicates that the position Li of the communication terminal device 20 is derived in such a way that a value indicated with the numerical expression following Σ is minimized. Specifically, the estimation unit 11 specifies the position Li of minimizing a value derived by squaring RSSI differences (errors) between the measurement result 151 and the signal transmission model 152 with respect to AP1 to AP3 and summing up the resultants.
The estimation unit 11 estimates the movement locus 153 by connecting the specified positions Li with a line for all the values of m.
Based on the restriction information 154 indicating a restriction (limitation) content relating to movement of the communication terminal device 20, the correction unit 12 illustrated in
In the present example embodiment, for example, it is assumed that the actual maximum speed at which the communication terminal device 20 moves is 1 meter per second (m/s). Further, in the first processing among the repeated processing executed by the wireless communication failure analysis device 10, which will be described later, the control unit 14 to be described later sets the maximum speed indicated in the restriction information 154 to be, for example, 3 m/s that is higher than the actual maximum speed, as an initial value.
Further, the correction unit 12 generates the corrected movement locus 155 by correcting the movement locus 153 estimated by the estimation unit 11, in such a way as to satisfy that the maximum speed at which the communication terminal device 20 moves is 3 m/s. For example, the correction unit 12 can correct the movement locus 153 described above by solving a linear scheduling question with a limitation for minimizing the distance (error) from the movement locus 153.
Based on the corrected movement locus 155 generated by the correction unit 12 and the measurement result 151, the generation unit 13 exemplified in
Note that, in Expression 4, LmSTA indicates a position (coordinate) of the communication terminal device 20 in the corrected movement locus 155 when the mth RSSI is measured after the communication terminal device 20 starts movement. “Set” is a function for deriving a set of positions (coordinates) of points dividing a line connecting a position LAP
The generation unit 13 derives the variable value XGrid(j) in simultaneous equations expressed in Expression 4 relating to k (k is any of 1 to 3 in the present example embodiment) and all the values for m by using a method such as a least-squares method, and thus estimates a presence situation of an obstacle.
The control unit 14 illustrated in
At each time of executing the processing in the repeated processing described above, the control unit 14 according to the present example embodiment updates the maximum speed indicating the restriction content relating to movement of the communication terminal device 20 in such a way that the maximum speed is gradually reduced from the initial value. Here, as the maximum speed relating to movement of the communication terminal device 20 is higher, the range, which matches with the measurement result 151 exemplified in
Specifically, in other words, as the maximum speed relating to movement of the communication terminal device 20 is lower, the range, which matches with the measurement result 151 exemplified in
In the present example embodiment, as described above, it is assumed that, in the actual movement locus exemplified in
The control unit 14 outputs the corrected movement locus 155 generated finally by the correction unit 12, which is exemplified in
Next, with reference to a flowchart of
The estimation unit 11 sets, as the initial value of the obstacle estimation result 156, that there is no obstacle that affects the wireless communication environment between the communication terminal device 20 and AP1 to AP3 (Step S101). The control unit 14 sets a value (for example, 3 m/s), which is greater than an actual maximum speed αz (for example, 1 m/s), as an initial value of a maximum speed α relating to movement of the communication terminal device 20, which is indicated in the restriction information 154 (Step S102).
The estimation unit 11 generates or updates the signal transmission model 152, based on the obstacle estimation result 156 (Step S103). The estimation unit 11 estimates the movement locus 153, based on the measurement result 151 and the signal transmission model 152 (Step S104). The correction unit 12 generates or updates the corrected movement locus 155 derived by correcting the movement locus 153 in such a way as to satisfy the restriction content (the maximum speed α) indicated in the restriction information 154 (Step S105).
The generation unit 13 updates the obstacle estimation result 156, based on the corrected movement locus 155 and the measurement result 151 (Step S106). The control unit 14 subtracts a predetermined value β (for example, 0.2 m/s) from the maximum speed α (Step S107).
When the maximum speed α is equal to or higher than the actual maximum speed αz (No in Step S108), the processing returns to Step S103 under control of the control unit 14. When the maximum speed α is lower than the actual maximum speed αz (Yes in Step S108), the control unit 14 outputs the obstacle estimation result 156 and the corrected movement locus 155 to the management terminal device 30 (Step S109), and the whole processing is terminated.
The wireless communication failure analysis device according to the present example embodiment is capable of analyzing a presence situation of an obstacle that affects the wireless communication state efficiently and with high accuracy. The reason for this is because the wireless communication failure analysis device according to the present example embodiment repeatedly executes the operations of estimating the movement locus of the wireless terminal device, based on the measurement result of the communication state and the estimation result relating to the presence situation of the obstacle, correcting the movement locus, based on the restriction content relating to movement of the communication terminal device, and generating the estimation result, based on the corrected movement locus and the measurement result, while gradually strengthening the restriction content.
Effects achieved by the wireless communication failure analysis device 10 according to the present example embodiment are described in detail below.
For example, at a site where an environment relating to the wireless communication changes rapidly, it has been expected to establish a stable wireless communication environment more securely and efficiently. Further, when a suitable measure capable of improving a deteriorated wireless communication state is to be taken efficiently, there is a problem in analyzing a detailed cause for deteriorating the wireless communication state efficiently and with high accuracy, for example, analyzing whether the cause is attenuation of signal strength due to an obstacle present at a specific location, a long distance between a wireless terminal device and an access point being a communication destination, or the like.
In view of the problem, the wireless communication failure analysis device 10 according to the present example embodiment includes the estimation unit 11, the correction unit 12, the generation unit 13, and the control unit 14, and is operated as described above with reference to
Specifically, when executing estimation of a presence situation of an obstacle that affects the wireless communication state and estimation of the movement locus 153 of the communication terminal device 20, which is required for the estimation of the presence situation of the obstacle, the wireless communication failure analysis device 10 according to the present example embodiment firstly starts estimation of the restriction content relating to movement of the communication terminal device 20, by using a more weakened (eased) value than the actual value, as exemplified in
This indicates that estimation is started at low accuracy for preventing wrong estimation directivity, and then estimation accuracy is gradually increased. Further, because the wireless communication failure analysis device 10 executes the operations described above, the information provided for estimating a presence situation of an obstacle is only required to include the measurement result 151, the information indicating the positions at which the access points are installed, and limited information such as the restriction information 154. Therefore, the wireless communication failure analysis device 10 according to the present example embodiment is capable of analyzing a presence situation of an obstacle that affects the wireless communication state efficiently and with high accuracy.
Further, the control unit 14 of the present example embodiment sets, as a condition used for determining whether to terminate the above-mentioned repeated processing, the restriction content (for example, the maximum movement speed is 1 m/s) relating to movement of the communication terminal device 20 when the measurement result 151 is acquired. The control unit 14 sets, as the initial value of the restriction information 154, the restriction content (for example, the maximum movement speed is 3 m/s) which is weaker than the restriction content relating to movement of the communication terminal device 20 when the measurement result 151 is acquired. Further, the control unit 14 generates the restriction information 154 indicating the maximum speed or the maximum acceleration relating to movement of the communication terminal device 20, in such a way that the maximum speed or the maximum acceleration is gradually reduced. With this, the wireless communication failure analysis device 10 according to the present example embodiment is capable of easily executing analysis of a presence situation of an obstacle efficiently and with high accuracy.
Further, in the present example embodiment described above, the communication terminal device 20 includes the communication state measurement unit 21, but the communication state measurement unit 21 is only required to be included in at least any one of the communication terminal device 20 and the access points. Alternatively, the communication state measurement unit 21 may be a single device having a communication function (for example, a dedicated measurement device) installed in the vicinity of the access points.
The wireless communication failure analysis device 40 according to the present example embodiment includes an estimation unit 41, a correction unit 42, a generation unit 43, and a control unit 44.
The estimation unit 41 estimates a movement locus 410 of a communication terminal device communicable with access points installed at known positions, based on a measurement result 400 indicating the communication state between the access points and the communication terminal device, which changes along with movement of the communication terminal device, and based on an estimation result 430 relating to a presence situation of an obstacle that affects the communication state.
The correction unit 42 corrects the movement locus 410, based on restriction information 441 indicating a restriction content relating to movement of the communication terminal device.
The generation unit 43 generates the estimation result 430, based on a corrected movement locus 420 and the measurement result 400.
The control unit 44 generates the restriction information 441 in such a way as to gradually strengthen the restriction content until the restriction content satisfies a condition 440, and executes control in such a way that estimation of the movement locus 410 by the estimation unit 41, correction of the movement locus 410 by the correction unit 42 based on the generated restriction information 441, and generation of the estimation result 430 by the generation unit 43 are repeatedly executed.
The wireless communication failure analysis device 40 according to the present example embodiment is capable of analyzing a presence situation of an obstacle that affects the wireless communication state efficiently and with high accuracy. The reason for this is because the wireless communication failure analysis device 40 repeatedly executes the operations of estimating the movement locus of the wireless terminal device, based on the estimation result relating to the measurement result of the communication state and the presence situation of the obstacle, correcting the movement locus, based on the restriction relating to movement of the communication terminal device, and generating the estimation result, based on the corrected movement locus and the measurement result, while gradually strengthening the restriction.
In each of the example embodiments described above, each of the units in the wireless communication failure analysis device illustrated in
Note that division of the units illustrated in the drawings is a configuration for convenience of the description, and various configurations can be conceived for implementation. One example of a hardware environment in this case is described with reference to
As constituent elements, the information processing device 900 illustrated in
a reader/writer 908 capable of reading and writing data stored in a recording medium 907 such as a compact disc read-only memory (CD-ROM); and
Specifically, the information processing device 900 including the constituent elements described above is a commonly-used computer in which those elements are connected to one another via the bus 906. The information processing device 900 may include a plurality of CPUs 901, or may include the CPU 901 including a multi-core.
Further, the present invention described with the example embodiments described above as examples provides the information processing device 900 illustrated in
Further, in this case, as a method of providing the computer program in the hardware, a general procedure can be currently employed. For example, the procedure includes a method of installing the computer program in the device via the recording medium 907 of various types such as a CD-ROM, a method of downloading the computer program from the outside via a communication network such as the Internet, and the like. Further, in such a case, it can be regarded that the present invention is constituted of codes forming the computer program or the recording medium 907 in which the codes are stored.
While the invention has been particularly shown and described with reference to exemplary embodiments thereof, the invention is not limited to these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims.
Note that a part or an entirety of each of the example embodiments described above may be described as in the following supplementary notes. However, the present invention described as an example in each of the example embodiments described above is not limited to the following.
A wireless communication failure analysis device including:
The wireless communication failure analysis device according to Supplementary Note 1, wherein
The wireless communication failure analysis device according to Supplementary Note 1 or 2, wherein
The wireless communication failure analysis device according to any one of Supplementary Notes 1 to 3, wherein
The wireless communication failure analysis device according to any one of Supplementary Notes 1 to 4, wherein
The wireless communication failure analysis device according to any one of Supplementary Notes 1 to 5, wherein
The wireless communication failure analysis device according to any one of Supplementary Notes 1 to 6, wherein
The wireless communication failure analysis device according to any one of Supplementary Notes 1 to 7, wherein
The wireless communication failure analysis device according to any one of Supplementary Notes 1 to 8, wherein
A wireless communication failure analysis system including:
A wireless communication failure analysis method being executed by an information processing device, the method including:
A recording medium that stores a wireless communication failure analysis program for causing a computer to execute:
This application is based upon and claims the benefit of priority from Japanese patent application No. 2019-002687, filed on Jan. 10, 2019, the disclosure of which is incorporated herein in its entirety by reference.
Number | Date | Country | Kind |
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2019-002687 | Jan 2019 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2019/047755 | 12/6/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2020/144987 | 7/16/2020 | WO | A |
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International Search Report for PCT Application No. PCT/JP2019/047755, dated Jan. 7, 2020. |
English translation of Written opinion for PCT Application No. PCT/JP2019/047755, dated Jan. 7, 2020. |
Number | Date | Country | |
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20220110006 A1 | Apr 2022 | US |