WO2016204243A1

WO2016204243A1 - Positioning method and positioning system

Info

Publication number: WO2016204243A1
Application number: PCT/JP2016/067975
Authority: WO
Inventors: 忠信潘
Original assignee: 忠信潘
Priority date: 2015-06-19
Filing date: 2016-06-16
Publication date: 2016-12-22
Also published as: JP2017009368A

Abstract

[Problem] To provide a positioning method, positioning system, and positioning server capable of accurately detecting the position of a wireless terminal that moves in an indoor space. [Solution] The present invention is a positioning method that receives a probe request frame from a wireless terminal moving in a position measurement space by at least three access points with known coordinate values that are provided in the position measurement space and that positions the wireless terminal with the RSS value of the received probe request frame, wherein the method autoadaptively finds with the RSS value of a beacon frame that is sent and received at a predetermined interval between the access points an approximate curve that expresses the relationship between the RSS value and distance, selects at least three of the access points, applies the RSS value of the probe request frame received by the access points to the respective approximate curve obtained just prior, and determines the position of the wireless terminal by a three-point positioning method.

Description

Positioning method, positioning system

The present invention relates to a positioning system that measures the position of a wireless terminal having a wireless transmission function, and more particularly to a positioning method and a positioning system that can improve the accuracy of position detection of a wireless terminal.

In recent years, as a new service for wireless terminals typified by mobile phones and smartphones, a position information service has been proposed in which the location of wireless terminals is measured in real time and the facilities providing the service in the vicinity are displayed on a map. ing. Based on such location information service, the user knows the location of the facility providing the target service and can go there without hesitation.

The location information service is convenient for the user, but it also provides benefits for the service provider depending on how it is used. For example, a user's flow line can be known by providing a location information service. As a result, the behavior and orientation of the person can be estimated, so that the user's position information becomes important context information when developing the business. For this reason, it is expected that a technology capable of measuring the position (positioning) of a wireless terminal with high accuracy will become increasingly important in the future.

As a typical example of the position measurement technology of a wireless terminal, use of GPS (Global Positioning System) can be mentioned. A car navigation system detects the position of a vehicle using GPS, and provides surrounding information and driving route information to a destination. GPS is used for applications based on various position information, but on the other hand, although it is effective outdoors, there is a problem that it is difficult to sufficiently receive a positioning satellite signal in an indoor environment. GPS also has a problem that the accuracy of estimating the position of a wireless terminal in an indoor environment is low due to the problem that positioning accuracy is greatly affected by disturbance. Furthermore, applications such as user flow management in indoor environments require positioning accuracy that is one digit higher than GPS. For this reason, various techniques for improving the accuracy of indoor positioning have been proposed.

As one of indoor positioning technologies, there is a positioning method using a wireless local area network (abbreviated as “WLAN”). WLAN positioning methods mainly include arrival time (Time of Arrival, abbreviation: TOA) positioning method, arrival time difference (Time Difference of Arrival, abbreviation: TDOA) positioning method, and received signal strength identifier (Received Signal Strength Identification, abbreviation). : RSS) positioning method.

One such RSS positioning method is a propagation model positioning method. In the propagation model positioning method, the signal strength at each position of the WLAN is calculated and the position of the wireless terminal is measured by utilizing the property that the signal transmitted in the air is attenuated by the propagation distance. However, the RSS positioning method has a problem that it is easily affected by indoor noise, reflection, temperature, humidity, and crowded conditions, and therefore, an error is caused in the positioning result. On the other hand, the RSS positioning method has an advantage that a positioning value can be obtained with a simple measuring device.

The following Patent Document 1 discloses a method for determining whether a signal between an access point and a terminal is affected by reflection in order to prevent degradation in positioning accuracy due to indoor reflection in the WLAN positioning method. Discloses a technique for improving the positioning accuracy. Specifically, the location service information of the AP in the set of measurement APs is acquired by the positioning server, the measurement 3AP in the set of measurement APs is selected according to a preset rule, and the first coordinates of the terminal are set. Calculate, obtain a calculated RSS value of any unmeasured AP of the measurement 3AP in the first coordinate according to a preset propagation model signal graph, and calculate the RSS value of the unmeasured AP as a measured RSS value and a preset threshold If it is not smaller than the difference between the measurement 3AP, it is determined that the signal of the unmeasured AP is not affected by reflection, it is determined whether all the measurement 3AP is measured according to the identifier of the AP, and all the measurement 3AP is measured The first coordinate is used as the position coordinate of the terminal, and the terminal is positioned.

Patent Document 2 listed below receives a plurality of anchors from a plurality of anchors in a mobile terminal in a positioning method for positioning the position of a mobile terminal in order to achieve highly accurate positioning using RSS values in a positioning method, a positioning system, and a program. Obtain the current wireless signal strength, determine the range of the distance from each anchor of the mobile terminal from the relationship between the distance from the plurality of anchors to the mobile terminal and the wireless signal strength obtained in advance, from each determined anchor The range of the position of the mobile terminal is narrowed down to the first range by the method of performing three-point positioning, and the distance from the two anchors to the mobile terminal that forms each combination for all combinations of the two anchors A range of the position of the mobile terminal corresponding to the disturbance parameter is obtained from the range of the difference, and the range of the position of the mobile terminal thus obtained is calculated between the range of the position and the first range. Refine to a second range that is formed in the region, it discloses a technique for positioning the terminal.

As described above, in the position detection technique based on the RSS value, in order to calculate the distance from the received signal strength, it is necessary to model distance attenuation in the environment. For this reason, both of Patent Document 1 and Patent Document 2 described above measure RSS values at various positions and distances in the use environment in advance, obtain approximate curves of distance and signal strength, and model the propagation environment. Yes. Therefore, the position estimation accuracy greatly depends on the approximation accuracy of the distance attenuation model. Further, prior measurement is performed to obtain a distance attenuation model, and the position of the wireless terminal is estimated based on the distance attenuation model based on the prior measurement.

However, in the actual environment, the strength of the RSS value changes dynamically depending on the environmental conditions, so that there is a problem that it is not possible to cope with changes in the environment only by prior measurement. In addition, distance attenuation varies depending on the location such as the center of the space or near the wall. Therefore, when modeling with one distance attenuation model, there is a problem that the estimation accuracy is reduced due to the mismatch of the distance attenuation models depending on the location.

JP 2013-221943 A JP 2012-255673 A

Accordingly, an object of the present invention is to detect the position of a wireless terminal that moves in an indoor space based on the RSS value, even if the space of the moving wireless terminal is different, and RSS that is received from the same distance depending on the environment and time. An object of the present invention is to provide a positioning method, a positioning system, and a positioning server that can detect the position of a wireless terminal with high accuracy even if the intensity of the value dynamically changes.

According to the first aspect of the present invention, a probe request frame from a wireless terminal moving in a position measurement space is provided in the position measurement space, and the coordinate values are received by a plurality of known access points. In the positioning method for positioning the wireless terminal by an approximate curve representing the relationship between the RSS value of the probe request frame and the distance,
Based on the RSS value of the beacon frame transmitted / received at a predetermined interval between the access points, an approximate curve representing the relationship between the RSS value and the distance is automatically applied, a plurality of the access points are selected, and the access points Positioning the position of the wireless terminal by applying the RSS value of the probe request frame received by each to the approximate curve.

The invention according to claim 2 is the positioning method according to claim 1, wherein at least three of the access points are selected, and the RSS value of the probe request frame received by the access points is automatically set to the approximate curve. Applicably applied, the position of the wireless terminal is measured by a three-point positioning method.

The invention according to claim 3 is the positioning method according to claim 1 or 2, wherein the RSS value of the beacon frame for obtaining the approximate curve is a plurality of RSS values obtained within a predetermined calculation period. Of these, the RSS value excluded according to a preset rule is processed, digitized, and calculated.

Invention of Claim 4 is the positioning method of Claim 1 or 2, Comprising: The RSS value of the said probe request | requirement flame | frame applied to an approximated curve is the said some RSS obtained within the predetermined | prescribed calculation period. Among the values, the RSS values excluded according to a preset rule are processed and digitized.

A fifth aspect of the present invention is the positioning method according to any one of the first to fourth aspects, wherein the approximate curve is obtained by the following mathematical formula 1.

(Formula 1)
here,
RSS value: Received signal strength (dBm), D: Distance (m), constant n: Rate constant at which the signal attenuates A: RSS value 1 meter away from the destination access point

The invention according to claim 6 is the positioning method according to any one of claims 1 to 5, wherein the distance between the selected access points does not exceed 10 meters.

The invention according to claim 7 is the positioning method according to any one of claims 3 to 6, wherein the calculation period is shifted by a predetermined time and the calculation period is repeated a plurality of times to obtain the plurality of RSS values. It is characterized by.

According to an eighth aspect of the present invention, a plurality of access points for receiving a probe request frame from a wireless terminal moving in a position measurement space, the coordinate values of which are known, and the probe request frame received by the access point are accessed. An access log collection server that records as an access log for each point and / or the position measurement space, and an approximate curve that represents a relationship between an RSS value and a distance of the probe request frame recorded in the access log collection server. In a positioning system equipped with a positioning server that measures the position of a terminal,
The access point includes a receiving unit that receives a beacon frame transmitted by another access point and its RSS value,
The access log collection server includes a recording unit that records the RSS value and beacon frame received by the access point for each access point and / or the location measurement space,
The positioning server automatically and adaptively calculates an approximate curve representing a relationship between an RSS value and a distance from an RSS value of a beacon frame recorded in the recording unit and a coordinate value of the access point, and the probe request A positioning system comprising a coordinate calculation engine that applies an RSS value of a frame to the approximate curve and calculates coordinates of the wireless terminal.

The invention according to claim 9 is the positioning system according to claim 8, wherein the coordinate calculation engine is set in advance among RSS values of the plurality of beacon frames obtained in a predetermined calculation period. An RSS value other than those excluded according to the rules is processed under a predetermined condition and converted into a numerical value to obtain the approximate curve.

The invention according to claim 10 is the positioning system according to claim 8, wherein the coordinate calculation engine is set in advance among RSS values of the plurality of probe request frames obtained in a predetermined calculation period. An RSS value other than those excluded according to the rules is processed under a predetermined condition, digitized, applied to the approximate curve, and means for positioning the position of the wireless terminal is provided.

The invention according to claim 11 is the positioning system according to any one of claims 8 to 10, wherein the coordinate calculation engine processes and specifies the RSS value while shifting the calculation period by a predetermined time. It is provided with.

As described above, according to the present invention, in the technology for detecting the position of a wireless terminal moving in an indoor space based on the RSS value, even if the space of the moving wireless terminal is different, it is received from the same distance depending on the environment and time. It is possible to provide a positioning method, a positioning system, and a positioning server capable of detecting a position with high accuracy even when the strength of the ground to be changed dynamically.

It is a lineblock diagram of positioning system 1 which is one embodiment of the present invention. It is the figure which showed typically the function of each apparatus which comprises the positioning system which measures the position of the radio | wireless terminal 100 using the RSS value from the radio | wireless terminal 100. FIG. 6 is a diagram illustrating a data structure that an access point 110 transmits to an access log collection server 30. FIG. It is a coordinate calculation process flowchart. It is the flowchart which showed the processing flow of calibration. It is the figure which showed the outlier filtering process typically. It is the figure which calculated | required the relationship between distance and an RSS value. It is the figure which showed the access point selected by the distance between access points. It is the figure which showed the relationship between a calculation period and a shift period.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a positioning system 1 according to an embodiment of the present invention. The positioning system 1 can estimate the position of the radio terminal 100 moving in such a location, such as the position measurement space 10, for example, the 1F or 2F floor of a mall street. Moreover, the flow line can be managed. The position measurement space 10 is preferably provided with at least three or more access points 110. This is because the position of the wireless terminal 100 is estimated by the three-point positioning method.

The wireless terminal 100 transmits a probe request frame to the access point 110 in the position measurement space 10. The access point 110 receives this, authenticates the wireless terminal 100, and permits connection to the WLAN network 20. As a result, the wireless terminal 100 can access the WLAN server and the Internet.

The access log collection server 30 and the positioning server 40 are connected to the WLAN network 20. The access log collection server 30 classifies the data included in the probe request frame (Probe Request Frame) transmitted from the wireless terminal 100 to the access point 110 for each position measurement space 10 and stores the data in the access log database 50. In addition, the access log collection server 30 similarly accumulates data included in a beacon frame (beacon frame) described later in the access log database 50.

The positioning server 40 calculates the coordinates of the wireless terminal 100 based on the access log data stored in the access log database 50, classifies the positioning results of the terminal for each position positioning space 10, and stores them in the positioning result database 60. Output.

FIG. 2 shows positioning in which the position of the wireless terminal 100 is measured using a received signal strength identifier (Received Signal Strength Identification, abbreviated as RSS) included in a probe request frame transmitted from the wireless terminal 100 to the access point 110. 3 is a block diagram illustrating functions of devices included in the system 1. FIG. FIG. 3 is a diagram showing a data structure that the access point 110 transmits to the access log collection server 30.

In FIG. 2, the wireless terminal 100 transmits a probe request frame to the access point 110 installed in the space where the wireless terminal 100 is located. Each access point 110 receives the probe request frame transmitted from the wireless terminal 100, and when receiving the probe request frame from the wireless terminal 100, the RSS value, the frame type, the reception time, the MAC address of the wireless terminal (Media Access Record Control (address) etc.

Further, each access point 110 transmits a probe response frame (Probe Response Frame) in response to the probe request frame from the wireless terminal 100. In addition, the access point includes a receiving unit that receives beacon frames transmitted from other access points at predetermined intervals. That is, by providing a function that each access point can receive a beacon frame that has been received only by the wireless terminal 100 in the past, it is possible to know the RSS value of a beacon frame transmitted / received between access points with known coordinate values. it can. Thereby, the relationship between the dynamically changing distance and the RSS value can be automatically applied.

The access point 110 receives the probe request frame and the beacon frame, its own IP address, the frame type indicating the type of the probe request frame or the beacon frame, and the wireless terminal that has transmitted the probe request frame. The MAC address and the received RSS value are transmitted to the access log collection unit 300 provided in the access log collection server 30 in a data structure as shown in FIG.

The access log collection unit 300 classifies the IP address, the type of the received probe request frame or beacon frame transmitted from the access point 110 for each position measurement space 10 and records it in the access log database 50.

The coordinate calculation engine 400 provided in the positioning server 40 calculates the coordinates of the wireless terminal 100 based on the data recorded in the access log database 50 and records the result in the positioning result database 60. The coordinate calculation engine 400 obtains a position correspondence table 600 indicating the correspondence between the access point and the position of the wireless terminal.

FIG. 4 is a coordinate calculation processing flowchart showing the overall processing flow in which the coordinate calculation engine 400 calculates the coordinates of the wireless terminal 100 based on the data recorded in the access log database 50. First, the coordinates of the access point 110 are mapped (S1). In addition, since the positioning of the wireless terminal 100 is performed by the three-point positioning method, the coordinates of at least three or more access points are set.

Next, an access log that is a log that the wireless terminal 100 has accessed the access point 110 is processed in time series. If such processing is performed for a certain period, for example, 5 seconds, the access logs collected in 5 seconds are collectively processed for each wireless terminal 100 (for each MAC address) (S2). The setting of the calculation period is to make it easy to exclude error signals in a filtering process described later.

Next, the coordinate calculation engine 400 reads the access log data (S3), and executes calibration for each access point 110 (S4). By performing such calibration at predetermined intervals, even if the position measurement space 10 of the wireless terminal 100 moving in the indoor space is different, and even if the strength of the RSS value received from the same distance changes depending on the environment at that time The position of the wireless terminal 100 can be estimated with high accuracy.

FIG. 5 is a flowchart showing a calibration processing flow. In the calibration, first, one access point 110 installed in the position measurement space 10 is selected (S41). Next, all beacon frame logs having the selected access point 110 as a transmission source are acquired (S42).

The beacon frames transmitted with the selected access point 110 as the transmission destination are classified for each access point 110 of the transmission destination, and an outlier filtering process for excluding outliers of the RSS value is executed (S43).

Here, outlier filtering processing includes filtering processing according to environmental conditions such as Smirnov-Grubbs test and Thompson test, assuming that the deviation is divided by unbiased standard deviation, normal distribution, etc. preferable. In the present embodiment, outlier filtering processing as shown in FIG. 6 is performed.

In the outlier filtering process shown in FIG. 6, the RSS values of all beacon frames (S42) acquired within the calculation period are sorted in ascending order to obtain the overall median value (M1) of the RSS values. Next, the median value (M2) of the minimum RSS value (RSS1) and the overall median value (M1), and the median value (M3) of the overall median value (M1) and the maximum RSS value (RSSn) And RSS values not included between M2 and M3 are excluded as outliers (filtering process). After excluding outliers in this way, the median RSS value is determined.

When the median RSS value between the access points 110 within the calculation period is obtained, a relationship distribution between the RSS value and the distance is created using a spatial propagation loss model (The log-distance path loss model) (S44). .

FIG. 7A illustrates the RSS value within the calculation period from the RSS value (median value) after performing the above-described outlier processing and the distribution map of access points (distance between access points is known). It is the table | surface which calculated | required the relationship with RSS value. FIG. 7B is an approximate straight line between the distance obtained from FIG. 7A and the RSS value.

The relationship between the distance and the RSS value shown in FIG. 7 was obtained by the following formula 1 using the least square method.

(Formula 1)
Where RSS value: received signal strength (dBm), D: distance (m), constant n: rate constant at which the signal attenuates A: RSS value 1 meter away from the destination access point

The constants n and A are determined by the above equation 1 (S45), the presence or absence of the next log data is checked, and if there is log data, the process returns to S41 again to select the constant n and constant A from the access point selection (S42). When the processing is completed for all log data, the calibration is terminated (S46). The constant A can be obtained, for example, by providing at least one access point 1 meter away in the position measurement space 10.

Next, the probe request frame within the calculation period is divided into the destination access point and the MAC address of the wireless terminal, and the outlier filtering is performed, for example, by applying outlier filtering processing as shown in FIG. The value is applied to the approximate curve obtained earlier to obtain the distance between the wireless terminal 100 and the access point 110 (S5).

Here, as the approximate curve to which the RSS value of the probe request frame is applied, the optimum approximate curve is automatically applied according to the change in the environment of the position measurement space 10 (automatically applicable), and thus the wireless terminal 100 with high accuracy. Can be estimated.

For example, the coordinate calculation engine 400 selects the three access points 110 in order of distance from the wireless terminal 100, and calculates the coordinates of the access point 110 and the distance of the wireless terminal 100 from the access point (S5).

The position of the wireless terminal 100 is determined by three-point positioning of the coordinates of the wireless terminal 100 obtained from the three access points 110 (S6), and the coordinates of the wireless terminal 60 are recorded in the positioning result database 60 (S7).

When converting an RSS value into a distance, the error tends to increase as the distance increases. Therefore, for example, as shown in FIG. 8, when it is set that the selection of an access point farther than the distance represented by d3 is not permitted, access point 1 (AP1) is access point 2 ポイント (AP2), access point It is preferable that only 4 (AP4) and access point 5 (AP5) are subjected to calibration processing. On the other hand, the access point 5 (AP5) preferably uses all the access points (AP1 to AP4, AP6) as objects of the calibration process.

In addition, if the angle between the selected access point and the access point is smaller than 15 °, the accuracy of the three-point positioning method is lowered. Therefore, select at least three access points whose angle between the access points is larger than 15 °. It is preferable to do.

FIG. 9 is a diagram showing the relationship between the calculation period and the shift period. As shown in FIG. 9, when setting the calculation period, it is preferable to provide calibration by shifting the calculation period by a certain period (shift period). This is because the position of the wireless terminal can be determined with high accuracy from the RSS value by setting the calculation period and the shift period.

According to the present invention, the position of the wireless terminal can be detected with high accuracy even if the space of the moving wireless terminal is different or the strength of the RSS value received from the same distance changes dynamically according to the environment and time. A positioning method, a positioning system, and a positioning server can be provided.

DESCRIPTION OF SYMBOLS 1 Positioning system 10 Position measurement space 20 WLAN network 30 Access log collection server 40 Positioning server 50 Access log database 60 Positioning result database 100 Wireless terminal 300 Access log collection part 400 Coordinate calculation engine 600 Position correspondence table

Claims

A probe request frame from a wireless terminal moving in the position measurement space is received in a plurality of access points provided in the position measurement space and whose coordinate values are known, and the RSS value and distance of the received probe request frame In a positioning method for positioning the wireless terminal by an approximate curve representing the relationship of
Based on the RSS value of the beacon frame transmitted / received at a predetermined interval between the access points, an approximate curve representing the relationship between the RSS value and the distance is automatically applied, a plurality of the access points are selected, and the access points Positioning the position of the wireless terminal by applying the RSS value of the probe request frame received by each to the approximate curve.
At least three access points are selected, an RSS value of the probe request frame received by the access point is applied to the approximate curve, and the position of the wireless terminal is measured by a three-point positioning method. Item 4. The positioning method according to item 1.
The RSS value of the beacon frame for obtaining the approximate curve is calculated by processing and quantifying an RSS value excluded in accordance with a preset rule among the plurality of RSS values obtained within a predetermined calculation period. The positioning method according to claim 1 or 2.
The RSS value of the probe request frame applied to the approximate curve is obtained by processing and digitizing an RSS value excluded according to a preset rule from among the plurality of RSS values obtained within a predetermined calculation period. The positioning method according to claim 1 or 2, characterized in that.
The positioning method according to claim 1, wherein the approximate curve is obtained by the following mathematical formula 1.

(Formula 1)
Where RSS value: received signal strength (dBm), D: distance (m), constant n: rate constant at which the signal attenuates A: RSS value 1 meter away from the destination access point
The positioning method according to any one of claims 1 to 5, wherein a distance between the selected access points does not exceed 10 meters.
The positioning method according to any one of claims 3 to 6, wherein the plurality of RSS values are obtained by repeating the calculation period a plurality of times by shifting the calculation period by a predetermined time.
A plurality of access points whose coordinate values are known for receiving probe request frames from wireless terminals moving in the position measurement space, and the probe request frames received by the access points for each of the access points and / or the position measurement spaces An access log collecting server that records as an access log, and a positioning server that measures the position of the wireless terminal by an approximate curve that represents a relationship between an RSS value and a distance of the probe request frame recorded in the access log collecting server; In the positioning system with
The access point includes a beacon frame transmitted by another access point and a reception unit that receives the RSS value,
The access log collection server includes a recording unit that records the RSS value and beacon frame received by the access point for each access point and / or the location measurement space,
The positioning server automatically and adaptively calculates an approximate curve representing a relationship between an RSS value and a distance from an RSS value of a beacon frame recorded in the recording unit and a coordinate value of the access point, and the probe request A positioning system comprising a coordinate calculation engine that applies an RSS value of a frame to the approximate curve and calculates coordinates of the wireless terminal.
The coordinate calculation engine processes RSS values other than those excluded in accordance with a preset rule among a plurality of RSS values of the beacon frames obtained during a predetermined calculation period, converts them into predetermined values, and calculates the approximate curve The positioning system according to claim 8, further comprising means for obtaining
The coordinate calculation engine processes the RSS values other than those excluded in accordance with a preset rule from among the RSS values of the plurality of probe request frames obtained in a predetermined calculation period under a predetermined condition, and converts the values into numerical values. 9. The positioning system according to claim 8, further comprising means for measuring a position of the wireless terminal applied to a curve.
11. The positioning system according to claim 9 or 10, wherein the coordinate calculation engine includes means for processing and specifying the RSS value while shifting the calculation period by a predetermined time.