KR20150124658A - Method and device for estimating indoor location - Google Patents

Abstract

A method and device for estimating indoor location according to an embodiment of the present invention includes: a step of collecting received signal strength indication (RSSI) information from at least one access point (AP); a step of calculating a signal estimate distance that is distance from a terminal to at the least one AP based on the RSSI information; a step of calculating a coordinate estimate distance that is a distance from coordinates which represent the location candidate of the terminal to the at least one AP; and a step of estimating the indoor location of the terminal based on a coordinate which minimizes an error between the coordinate estimate distance and the signal estimate distance among the coordinates.

Description

[0001] METHOD AND DEVICE FOR ESTIMATING INDOOR LOCATION [0002]

Embodiments of the present invention relate to a method and apparatus for estimating a position of a terminal in an indoor environment using RSSI information of an Access Point (AP).

One of the main functions of mobile devices used in modern society is current location estimation. Generally, the current location estimation is done through GPS. GPS is reflected and refracted on the outer wall of the building and does not provide a reliable value in the indoor environment. Therefore, a methodology for estimating a more accurate position in a room is being studied.

Techniques that are commonly used to estimate position in mobile devices such as smart phones are RTT (Round Trip Time) and RSSI (Received Signal Strength Indication) of RF signals. In the case of RTT, RSSI is actually being used much more because it requires special hardware. RSSI fingerprinting is one of the best performing technologies currently using RSSI, but it has a disadvantage of having a considerable installation / maintenance cost.

On the other hand, there are technologies that are hardly installed / maintained. Examples of such techniques include Weighted Centroid Localization (WCL) using RSSI, dead reckoning using a sensor of a mobile device, etc., Due to the limitations, the accuracy is very low and there is a considerable burden on commercialization.

The prior art has such a large variation. Instead of having a very high installation / maintenance cost, the performance is excellent, or conversely, the installation / maintenance cost is very low, but the performance is very poor. This makes it difficult for both technologies at both extremes to become commercially viable, because if the price is too high, the economics are poor, but if the performance is too low, it is the same technology.

Therefore, in order to provide simple and economical commercialization regardless of location, it is necessary to use a location estimation technique that has a low installation / maintenance cost and proper performance.

A related prior art is disclosed in Korean Patent Registration No. 10-0939354 entitled " Position Measurement Method and Apparatus Using Access Point, Registered Date: Jan. 21, 2010 ".

An embodiment of the present invention provides an indoor location estimation method and an indoor location estimation method capable of performing location estimation with the highest accuracy and reliability over a low cost estimation technique in an indoor environment using RSSI information of an AP.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, there is provided a method of estimating an indoor location, comprising: collecting Received Signal Strength Indication (RSSI) information from at least one AP; Calculating a signal estimation distance that is a distance from the terminal to the at least one AP based on the RSSI information; Calculating a coordinate estimated distance that is a distance from a plurality of arbitrary coordinates indicating the position candidate of the terminal to the at least one AP; And estimating an indoor position of the terminal based on a coordinate that minimizes an error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates.

Wherein the step of estimating the indoor position of the mobile terminal comprises the steps of: determining a difference between the signal estimation distance and the coordinate estimation distance as an error of a positioning of the plurality of arbitrary coordinates; Calculating a coordinate that minimizes the error among the plurality of arbitrary coordinates; And estimating a coordinate that minimizes the error as an indoor position of the terminal.

Estimating an indoor position of the mobile terminal includes calculating an error ratio indicating a value obtained by proportioning the error based on the signal estimation distance; Calculating a coordinate that minimizes the error ratio among the plurality of arbitrary coordinates; And estimating a coordinate for minimizing the error rate as an indoor position of the terminal.

The step of calculating the error ratio may include calculating a value (error / signal estimation distance) obtained by dividing the error by the signal estimation distance as the error ratio.

Calculating the coordinates to minimize the error ratio may include calculating coordinates among the plurality of arbitrary coordinates such that a sum of error rates for the at least one AP has a minimum value.

According to another aspect of the present invention, there is provided a method for estimating an indoor position, comprising: generating a correction coefficient for correcting an indoor estimated position of the terminal; And correcting the estimated indoor position of the terminal by applying the correction coefficient to the error ratio.

The generating of the correction factor may include generating the correction factor based on at least one of the number of the APs, the density of the AP, and the error of the RSSI information.

The magnitude of the correction coefficient may be inversely proportional to the number of APs.

The magnitude of the correction factor may be proportional to the density of the AP.

The magnitude of the correction coefficient may be proportional to the error of the RSSI information.

An indoor location estimation apparatus according to an embodiment of the present invention includes an RSSI information collection unit for collecting RSSI (Received Signal Strength Indication) information from at least one AP (Access Point); And calculates a signal estimation distance, which is a distance from the terminal to the at least one AP based on the RSSI information, and calculates a coordinate estimated distance, which is a distance from a plurality of arbitrary coordinates indicating a position candidate of the terminal to the at least one AP An estimated distance calculating unit for calculating an estimated distance; And a position estimating unit estimating an indoor position of the terminal based on a coordinate that minimizes an error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates.

Wherein the position estimating unit determines a difference between the signal estimation distance and the coordinate estimated distance as an error of a positioning of the plurality of arbitrary coordinates and calculates a coordinate that minimizes the error among the plurality of arbitrary coordinates, Can be estimated as the indoor position of the terminal.

Wherein the position estimating unit calculates an error ratio indicating a value obtained by proportioning the error based on the signal estimation distance, calculates coordinates to minimize the error ratio among the plurality of arbitrary coordinates, and minimizes the error ratio The coordinates can be estimated as the indoor position of the terminal.

The position estimating unit may calculate a value (error / signal estimation distance) obtained by dividing the error by the signal estimation distance as the error ratio.

The position estimating unit may calculate a coordinate such that a sum of error rates for the at least one AP among the plurality of arbitrary coordinates has a minimum value.

The indoor position estimating apparatus according to an embodiment of the present invention generates a correction coefficient for correcting an indoor estimated position of the terminal and applies a correction coefficient to the error rate to correct a indoor estimated position of the terminal And the like.

The position correction unit may generate the correction coefficient based on at least one of the number of the APs, the density of the APs, and the error of the RSSI information.

Wherein the position correction unit generates respective initial correction coefficients for the two or more when generating the correction coefficient based on at least two of the number of the APs, the density of the APs and the error of the RSSI information, And a final correction coefficient can be generated by multiplying the generated initial correction coefficients by the multiplication operation.

The details of other embodiments are included in the detailed description and the accompanying drawings.

According to an embodiment of the present invention, the indoor location can be estimated with high accuracy and reliability at low cost by estimating the location in the indoor environment based on the estimated distance using the RSSI information of the AP.

FIG. 1 is a block diagram illustrating an indoor location estimating apparatus according to an embodiment of the present invention. Referring to FIG.
2 is a diagram showing an example of the arrangement structure between arbitrary coordinates and APs when the coordinate estimation distance is calculated according to an embodiment of the present invention.
3 is a diagram showing an example of a reference table storing AP related information.
4 is a diagram showing an example of correction coefficients according to the number of APs.
5 is a diagram showing an example of correction coefficients according to AP density.
6 is a flowchart illustrating a method for estimating an indoor position according to an embodiment of the present invention.
FIG. 7 is a flowchart showing an example for specifically explaining the step of estimating the indoor position in FIG.
8 is a flow chart showing another example for specifically explaining the step of estimating the indoor position in FIG.
9 is a flowchart illustrating a method of estimating an indoor position according to another embodiment of the present invention.
FIGS. 10 and 11 are diagrams for comparing the errors in estimating the indoor position according to the prior art and the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and / or features of the present invention, and how to accomplish them, will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating an indoor location estimating apparatus according to an embodiment of the present invention. Referring to FIG.

1, an indoor position estimation apparatus 100 according to an exemplary embodiment of the present invention includes an RSSI information collection unit 110, an estimated distance calculation unit 120, a position estimation unit 130, a position correction unit 140 And a control unit 150. The control unit 150 may be a microcomputer. The indoor position estimation apparatus 100 may be mounted on a user's terminal or may be implemented in another terminal to perform the operation through interlocking with the user's terminal.

The RSSI information collecting unit 110 collects RSSI (Received Signal Strength Indication) information from at least one AP (Access Point). That is, the RSSI information collection unit 110 may collect RSSI information from nearby APs through WiFi scanning using a WiFi module of the terminal.

At this time, the RSSI information collecting unit 110 may know the availability of the AP and other related information through the reference table as shown in FIG. To this end, it is preferable that the reference table of FIG. 3 stores information on the availability of the AP, and X-coordinate, Y-coordinate, and AP name (unique identification information, ID) of the available AP.

Here, the AP may have a structure in which one or more wireless APs are located apart from each other at an arbitrary interval, and may communicate with the terminal through short-range wireless communication such as Wi-Fi.

In addition, the RSSI information is basic information necessary for estimating the indoor position of the terminal in one embodiment of the present invention. Accordingly, in one embodiment of the present invention, the indoor location of the terminal can be estimated using the RSSI information, thereby reducing installation and maintenance costs for indoor location estimation.

The estimated distance calculating unit 120 calculates a signal estimated distance, which is a distance from the terminal to the at least one AP, based on the RSSI information. At this time, the estimated distance calculating unit 120 stores the collected RSSI information in RSSI vs.. The signal estimation distance can be calculated by converting the distance using the distance model.

The estimated distance calculating unit 120 calculates a coordinate estimated distance that is a distance from a plurality of arbitrary coordinates indicating the position candidate of the terminal to the at least one AP.

For example, as shown in FIG. 2, a distance from each of a plurality of arbitrary coordinates (201, 202, 203) to each AP (210, 220) is called the coordinate estimation distance. Here, let X and Y be the distances to any one of the APs, and let x, y be any one of arbitrary coordinates 201, 202, and 203. The coordinate estimated distances, which are distances from the positions x and y to the AP, Can be expressed by Equation (1). Thus, the coordinate estimated distance can be determined from arbitrarily selected positions x, y rather than actual positions.

[Equation 1]

The position estimating unit 130 estimates an indoor position of the terminal based on coordinates that minimizes an error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates.

That is, the position estimating unit 130 determines the difference between the signal estimation distance and the coordinate estimation distance as an error of the positioning of the plurality of arbitrary coordinates, And estimates coordinates that minimize the error as the indoor position of the terminal.

Alternatively, the position estimator 130 may estimate the indoor position of the terminal using the error ratio as in Equation (2). The difference between the signal estimation distance and the coordinate estimation distance of a specific AP with respect to an arbitrary position x, y represents an error that the corresponding coordinate x, y has with respect to the corresponding AP.

&Quot; (2) "

In other words, it shows how far the actually obtained information is offset with respect to any coordinates x, y. Since the error occurs at a constant rate in proportion to the distance, the distance error is divided by the signal estimation distance as shown in the following Equation 2 in order to rate the distance error. Here, the reason why the error is divided into the signal estimation distance rather than the coordinate estimation distance is because the d value in the following equation (2) is the actual distance value, and the error has a ratio distribution according to d.

 When calculating the coordinates for minimizing the error ratio, the position estimating unit 130 may calculate the coordinates of the minimum error ratio so that the sum of error ratios for a plurality of APs among the plurality of arbitrary coordinates has a minimum value as shown in Equation (3) Can be calculated as coordinates for minimizing the error ratio.

That is, Equation (2) is an error calculation formula for one AP, and Equation (3) is an error calculation formula for a plurality of APs. If the values obtained from a plurality of APs are collected, it is highly likely that the coordinates x and y that minimize the overall error are probabilistic correct positions, so that a formula using a plurality of APs is used as shown in Equation 3 below.

&Quot; (3) "

In another embodiment, the position correcting unit 140 can estimate the indoor estimated position by applying a correction coefficient for correcting the indoor estimated position of the terminal to Equation (3), as shown in Equation (4).

&Quot; (4) "

In Equation (4), the correction coefficient is represented by k, and the correction coefficient k may be generated based on at least one of the number of the APs, the density of the APs, and the error of the RSSI information.

In Equation (3), when the same equation is applied regardless of the distance, the error value of the AP that is close to the same x and y values changes more greatly, so that the overall value tends to be greatly affected by the result of the near AP. Therefore, a correction coefficient k is applied as shown in Equation (4) in order to correct the error.

When the equation (3) is changed as shown in Equation (4), the estimated position is corrected according to the magnitude of the k value. This is a k-norm (size) of a vector having the number of APs as a dimension.

Here, the size of the correction coefficient is inversely proportional to the number of the APs, is proportional to the density of the APs, and is preferably proportional to the error of the RSSI information. For example, as shown in FIG. 4, it can be seen that the correction coefficient gradually decreases from 3 to 1.6 as the number of APs increases from three to seven. As shown in FIG. 5, the correction coefficient has a value of 1 when the density of the AP is low, 1.25 when the AP is low, and 2 when the density of the AP is low. Therefore, the correction coefficient gradually increases as the density of the AP increases Able to know.

The controller 150 may be configured to calculate the indoor position estimation apparatus 100 according to an embodiment of the present invention such that the RSSI information collector 110, the estimated distance calculator 120, the position estimator 130, The operation of the position correcting unit 140 and the like can be generally controlled.

Hereinafter, the calculation of the correction coefficient k used in the position correcting unit 140 will be described in more detail.

In the present invention, the adjustment of the k value is one of the main contents, and the improvement of the overall performance can be expected by automatically changing the k value.

If the value of k is greater than 1, even if n is constant in n ^k , (n + Δn) ^k , the difference between the two equations becomes large when n is large. The larger the k, the stronger the tendency. Therefore, as the value of k in Equation (4) becomes larger, a position that makes the overall error value constant is searched instead of finding a position having a small sum of error values.

The k-value calculation technique is based on the above-mentioned tendency. Since it is hard to know which k value is true only with the information actually obtained, the factor for determining the k value is obtained based on empirical information.

The factors affecting k value are as follows.

1. Number of connected APs

2. Error Tendency of RSSI

3. Configure the Location of the AP

When the value of k is small, it is greatly affected by the error ratio of the nearby AP. When the value of k is large, the influence is similar to AP close to the far AP. When the number of currently searched APs is small, the error of nearby APs is large, and if k is small, the error is greatly affected. Therefore, when the AP is searched for less, the value of k is increased to positively utilize the value of the AP that is somewhat distant.

On the contrary, when there are a large number of APs currently being searched, if the AP is affected by a remote AP, it is impossible to utilize the value of a nearby AP which is relatively accurate. Therefore, in order to more actively utilize the value of a nearby AP, Lower.

The error tendency of the RSSI also affects the determination of the k value. If the error of the RSSI is large, the nearby AP is also unreliable. Therefore, it is better to increase the k value and use the AP evenly. On the other hand, if the error of the RSSI is very small, a better effect can be obtained by using a method of actively using a nearby AP by lowering the k value.

In the case of the AP location configuration, it is better to increase the value of k in order to avoid a situation where the AP is strongly influenced by some APs. If the value of k is increased, a small number of APs avoids a large error, and a similar value is set as a whole. Therefore, if the k value is high in the structure in which the APs are located, if there are one or two APs in the opposite direction Can be avoided.

6 is a flowchart illustrating a method for estimating an indoor position according to an embodiment of the present invention.

Referring to FIGS. 1 and 6, in operation 610, the RSSI information collection unit 110 of the indoor location estimation apparatus 100 collects RSSI information from at least one AP.

Next, in step 620, the estimated distance calculating unit 120 of the indoor position estimating apparatus 100 calculates a signal estimation distance, which is a distance from the terminal to the at least one AP, based on the RSSI information.

Next, in step 630, the estimated distance calculating unit 120 of the indoor position estimating apparatus 100 calculates a distance to the at least one AP from a plurality of arbitrary coordinates indicating the position candidate of the terminal, .

Next, in step 640, the position estimating unit 130 of the indoor position estimating apparatus 100 calculates a distance between the signal estimation distance and the coordinate estimation distance, based on the coordinates that minimizes the error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates And estimates the indoor position of the terminal.

7 is a flowchart showing an example for specifically explaining step 640 of estimating the indoor position of FIG.

1 and 7, in step 710, the position estimation unit 130 of the indoor position estimation apparatus 100 calculates a difference between the signal estimation distance and the coordinate estimation distance by using the coordinates It is determined as an error of the positioning.

Next, in step 720, the position estimating unit 130 of the indoor position estimating apparatus 100 calculates coordinates for minimizing the error among the plurality of arbitrary coordinates.

Next, in step 730, the position estimating unit 130 of the indoor position estimating apparatus 100 estimates the coordinate for minimizing the error as the indoor position of the terminal.

8 is a flowchart showing another example for specifically explaining the step 640 of estimating the indoor position of FIG. In this embodiment, the accuracy of the indoor position estimation can be further improved by using the error ratio.

Referring to FIGS. 1 and 8, in step 810, the position estimation unit 130 of the indoor position estimation apparatus 100 calculates an error ratio indicating a value obtained by proportioning the error based on the signal estimation distance do.

Next, in step 820, the position estimating unit 130 of the indoor position estimating apparatus 100 calculates coordinates for minimizing the error ratio among the plurality of arbitrary coordinates.

Next, in step 830, the position estimating unit 130 of the indoor position estimating apparatus 100 estimates a coordinate for minimizing the error ratio as an indoor position of the terminal.

9 is a flowchart illustrating a method of estimating an indoor position according to another embodiment of the present invention.

Referring to FIGS. 1 and 9, in step 910, the RSSI information collection unit 110 of the indoor location estimation apparatus 100 collects RSSI information from at least one AP.

Next, in step 920, the estimated distance calculating unit 120 of the indoor position estimating apparatus 100 calculates a signal estimated distance, which is a distance from the terminal to the at least one AP, based on the RSSI information.

Next, in step 930, the estimated distance calculating unit 120 of the indoor position estimating apparatus 100 calculates a distance to the at least one AP from a plurality of arbitrary coordinates indicating a position candidate of the terminal, .

Next, in step 940, the position estimating unit 130 of the indoor position estimating apparatus 100 calculates a distance between the signal estimation distance and the coordinate estimation distance, based on the coordinates that minimizes the error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates And estimates the indoor position of the terminal.

Next, in step 950, the position correcting unit 140 of the indoor position estimating apparatus 100 generates a correction coefficient for correcting the indoor estimated position of the terminal.

Next, in step 960, the position correcting unit 140 of the indoor position estimating apparatus 100 corrects the indoor estimated position of the terminal by applying the correction coefficient to the error ratio.

FIGS. 10 and 11 are diagrams for comparing the errors in estimating the indoor position according to the prior art and the present invention. 10 and 11 (a) show errors in the indoor position estimation according to the related art, and Figs. 10 and 11 (b) show the indoor (C) shows an error in estimating the indoor position according to the embodiment of the present invention to which the correction coefficient is applied.

10 shows a case where APs are distributed evenly. In the case of the related art, the indoor position average estimation error is 10.9624 m, while the indoor position average estimation error according to the embodiment of the present invention without the correction coefficient is 7.36341 m , And the indoor position average estimation error according to the embodiment of the present invention in which the correction coefficient is applied is 7.21155 m. Based on this, it can be seen that the case of the present invention has a much lower average estimation error than in the prior art.

11 shows the case where APs are crowded. In the case of the related art, the indoor position average estimation error is 10.5048 m, whereas the indoor position average estimation error according to the embodiment of the present invention without the correction coefficient is 6.87729 m, and the correction coefficient, the indoor average estimation error according to an embodiment of the present invention is 5.86226m. On the basis of this, it can be seen that the performance of the present invention is further improved in the case of FIG. 11 compared to FIG. 10, that is, when the AP is crowded.

Embodiments of the present invention include computer readable media including program instructions for performing various computer implemented operations. The computer-readable medium may include program instructions, local data files, local data structures, etc., alone or in combination. The media may be those specially designed and constructed for the present invention or may be those known to those skilled in the computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floppy disks, and ROMs, And hardware devices specifically configured to store and execute the same program instructions. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

110: RSSI information collecting unit
120: Estimation distance calculating unit
130:
140:
150:

Claims (17)

A method for estimating an indoor location of a terminal,
Collecting Received Signal Strength Indication (RSSI) information from at least one Access Point (AP);
Calculating a signal estimation distance that is a distance from the terminal to the at least one AP based on the RSSI information;
Calculating a coordinate estimated distance that is a distance from a plurality of arbitrary coordinates indicating the position candidate of the terminal to the at least one AP; And
Estimating an indoor position of the terminal based on a coordinate that minimizes an error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates
And estimating the indoor position based on the estimated indoor position.
The method according to claim 1,
The step of estimating the indoor position of the terminal
Determining a difference between the signal estimation distance and the coordinate estimation distance as an error of a positioning of the plurality of arbitrary coordinates;
Calculating a coordinate that minimizes the error among the plurality of arbitrary coordinates; And
Estimating a coordinate for minimizing the error as an indoor position of the terminal
And estimating the indoor position based on the estimated indoor position.
The method according to claim 1,
The step of estimating the indoor position of the terminal
Calculating an error ratio indicating a value obtained by proportioning the error based on the signal estimation distance;
Calculating a coordinate that minimizes the error ratio among the plurality of arbitrary coordinates; And
Estimating a coordinate for minimizing the error ratio as an indoor position of the terminal
And estimating the indoor position based on the estimated indoor position.
The method of claim 3,
The step of calculating the error ratio
Calculating a value (error / signal estimation distance) obtained by dividing the error by the signal estimation distance as the error ratio
And estimating the indoor position based on the estimated indoor position.
The method of claim 3,
The step of calculating coordinates to minimize the error ratio
Calculating a coordinate such that, of the plurality of arbitrary coordinates, a sum of error rates for the at least one AP has a minimum value
And estimating the indoor position based on the estimated indoor position.
The method of claim 3,
Generating a correction coefficient for correcting an indoor estimated position of the terminal; And
And correcting the estimated indoor position of the mobile terminal by applying the correction coefficient to the error ratio
And estimating the indoor position of the vehicle.
The method according to claim 6,
The step of generating the correction coefficient
Generating the correction factor based on at least one of the number of the APs, the density of the APs and the error of the RSSI information
And estimating the indoor position based on the estimated indoor position.

8. The method of claim 7,
The magnitude of the correction factor is
Wherein the number of APs is inversely proportional to the number of APs.
8. The method of claim 7,
The magnitude of the correction factor is
Wherein the AP is proportional to the density of the AP.
8. The method of claim 7,
The magnitude of the correction factor is
Wherein the RSSI information is proportional to an error of the RSSI information.
An apparatus for estimating an indoor position of a terminal,
An RSSI information collecting unit for collecting RSSI (Received Signal Strength Indication) information from at least one AP (Access Point);
And calculates a signal estimation distance, which is a distance from the terminal to the at least one AP based on the RSSI information, and calculates a coordinate estimated distance, which is a distance from a plurality of arbitrary coordinates indicating a position candidate of the terminal to the at least one AP An estimated distance calculating unit for calculating an estimated distance; And
A position estimating unit estimating an indoor position of the terminal based on a coordinate that minimizes an error between the signal estimation distance and the coordinate estimation distance among the plurality of arbitrary coordinates,
And an indoor position estimating unit for estimating an indoor position of the vehicle.
12. The method of claim 11,
The position estimating unit
A coordinate calculating step of determining a difference between the signal estimation distance and the coordinate estimated distance as an error of a positioning of the plurality of arbitrary coordinates and calculating a coordinate that minimizes the error among the plurality of arbitrary coordinates, Is estimated as the indoor position of the terminal.
12. The method of claim 11,
The position estimating unit
Calculating an error ratio indicating a value obtained by proportioning the error on the basis of the signal estimation distance and calculating a coordinate for minimizing the error ratio among the plurality of arbitrary coordinates, As the indoor position of the vehicle.
14. The method of claim 13,
The position estimating unit
(Error / signal estimated distance) obtained by dividing the error by the signal estimation distance as the error ratio.
14. The method of claim 13,
The position estimating unit
And calculates a coordinate for causing a sum of error ratios for the at least one AP to have a minimum value among the plurality of arbitrary coordinates.
14. The method of claim 13,
A position correction unit for generating a correction coefficient for correcting an indoor estimated position of the terminal and correcting an indoor estimated position of the terminal by applying the correction coefficient to the error ratio,
Further comprising: an indoor position estimating unit for estimating an indoor position of the vehicle;
17. The method of claim 16,
The position correction unit
And generates the correction coefficient based on at least one of the number of the APs, the density of the AP, and the error of the RSSI information.

Images