KR101642186B1 - Location tracking method, location tracking system and recording medium for performing the method - Google Patents

Abstract

Disclosed is a position tracking method, a position tracking system, and a recording medium for performing the same, which can detect a current position of a user more accurately and quickly by minimizing an influence by an external variable and reducing calculation time for position tracking.
The location tracking system divides a space in a building into a predetermined size and receives signal intensity information of each AP from the mobile terminal and the mobile terminal measuring the signal intensity information of the AP for each generated coordinate, And a server for generating a radio map by grouping a plurality of coordinates located in the building in accordance with the cosine similarity, the positional accuracy And it is possible to estimate the current position of the user more quickly by reducing the calculation time.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a location tracking method, a location tracking system, and a recording medium for performing the same.

The present invention relates to a location tracking method, a location tracking system, and a recording medium for performing the same, and more particularly, to a location tracking method, a location tracking system, and a recording medium for performing the same, .

Current location tracking technology is one of the core technologies of ubiquitous society, and user 's location tracking technology using various communication methods is being studied.

An automatic navigation system using GPS satellites or a location service based on a mobile communication network is a well known technology. However, the location tracking technology using GPS satellites has a very low accuracy in location tracking, and there are many difficulties in using the GPS satellite in indoor and shaded areas. In recent years, indoor and near location tracking technologies using various communication technologies such as Wi-Fi, UWB, Bluetooth and RFID have been studied. Although the above-described technology has a limitation in tracking a location in a wide outdoor area such as a GPS, it can acquire highly accurate positioning information in a narrow area.

Here, there are two techniques for estimating a user's indoor position. The user can estimate the position of the current user by analyzing the intensity of a communication signal such as a Wi-Fi signal, or estimate the moving distance and direction of a pedestrian using a sensor Method.

However, a technique of tracking a user's position using a communication signal strength may cause an error due to a change in communication intensity or a weakened intensity due to external variables such as interferences or obstacles between various signals. Estimation of the user's position using the sensor may cause errors in calculation of the moving direction and the moving distance due to variables of the external environment such as gravity acceleration.

According to an aspect of the present invention, there is provided a position tracking method capable of minimizing the influence of an external variable and detecting a current position of a user more accurately and quickly by reducing calculation time for position tracking, a position tracking system, Media.

According to another aspect of the present invention, there is provided a location tracking system comprising: a mobile terminal for dividing a space located in a building into a predetermined size and measuring signal intensity information of the AP for each generated coordinate; And receiving the signal strength information of the AP for each coordinate from the mobile terminal, converting the signal intensity information of the AP into multidimensional vector information, calculating the cosine similarity between the multidimensional vector information and a predetermined basic vector, And a server for generating a radio map by grouping a plurality of coordinates located within the radio link.

The mobile terminal can transmit signal strength information of the AP measured for each of the coordinates and reliability information for each coordinate set by the designer to the server.

The server receives AP signal strength information from the mobile terminal, calculates a relative magnitude ratio of the signal strength, and constructs a multi-dimensional vector according to a relative magnitude ratio of the calculated signal strength.

The server may estimate the current location of the mobile terminal after constructing the radio map. Upon estimating the current location of the mobile terminal, the server receives the signal strength information of the AP from the mobile terminal, Calculates a cosine similarity between the multidimensional vector and a predetermined basic vector, selects a group grouped in the radio map according to the calculated cosine similarity, and determines a current position of the mobile terminal in the group It is possible to perform a similarity determination operation for estimation.

The server performs the similarity determination operation for estimating the current position of the mobile terminal by determining the degree of similarity between the signal intensity information of the AP measured by the mobile terminal and the signal intensity information by the coordinates stored in the radio map, The large coordinates can be estimated as the current position of the mobile terminal.

The location tracking method according to an embodiment of the present invention includes: calculating a multidimensional vector by converting signal strength information of an AP measured by a mobile terminal into a relative size ratio; calculating a cosine similarity between the multidimensional vector and a predetermined basic vector And generates a radio map including coordinate information and relative magnitude ratio information of the signal intensity from the APs for each of the plurality of grouped coordinates, and transmits the radio map to the mobile terminal Calculating a multidimensional vector using the AP signal strength information to calculate a cosine similarity with a basic vector, selecting any one of a predetermined group in the radio map, estimating a current position of the mobile terminal in the selected group, can do.

The method includes estimating a current position of the mobile terminal, continuously detecting movement of the mobile terminal by detecting a user's step of the mobile terminal, setting a step width according to a user's gender, You can set a threshold value.

Calculating a cosine similarity between the multidimensional vector and a predetermined basic vector and grouping the plurality of coordinates by dividing the size of the cosine similarity into a plurality of ranges and grouping a plurality of coordinates by each range, .

The method of claim 1, wherein selecting one of the predetermined groups in the radio map and estimating the current position of the mobile terminal in the selected group comprises: using the AP signal strength information transmitted from the mobile terminal Selecting a group to which the calculated cosine similarity belongs and detecting coordinates storing AP signal strength information most similar to the AP signal strength transmitted from the mobile terminal in the selected group.

The recording medium according to an embodiment of the present invention may be a computer-readable recording medium on which a computer program is recorded, for executing the method for tracking a position according to any one of the above-described methods.

According to the present invention, it is possible to improve the accuracy of the position tracking and reduce the calculation time, thereby estimating the current position of the user more quickly.

1 is a schematic diagram of a position tracking system according to an embodiment of the present invention;
2 is a conceptual diagram for explaining a radio map generation method of the position tracking system of FIG.
3 is a block diagram of a mobile terminal included in a location tracking system according to an embodiment of the present invention.
4 is a control block diagram of a server included in a location tracking system according to an embodiment of the present invention.
FIG. 5 is a conceptual diagram illustrating a radio map generation method performed by a location tracking system according to an embodiment of the present invention.
FIG. 6 is a conceptual diagram illustrating a method for tracking a current location of a mobile terminal included in a location tracking system according to an embodiment of the present invention.
7 is a flowchart illustrating a method of constructing a radio map of a location tracking system according to an embodiment of the present invention.
8 is a flowchart illustrating a method of estimating a position of a position tracking system according to an embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

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

FIG. 1 is a schematic conceptual diagram of a position tracking system according to an embodiment of the present invention, and FIG. 2 is a conceptual diagram for explaining a radio map generation method of the position tracking system of FIG.

The location tracking system 100 may include a mobile terminal 10 and a server 50.

The mobile terminal 10 and the server 50 can assign coordinates by dividing the interior of the building into a predetermined lattice. The mobile terminal 10 and the server 50 can construct the radio map by storing the signal information from the neighboring AP for each coordinate in the space.

The mobile terminal 10 can measure the signal strength from the neighboring APs according to coordinates in the space when the radio map is constructed. The mobile terminal 10 can transmit the signal intensity information of the plurality of APs and the reliability information for each coordinate to the server 50. [ The reliability information may be set by the designer in consideration of the degree of influence of the signal intensity depending on the surrounding environment, that is, the obstacle, and a plurality of measured values. Accordingly, the reliability information can be stored for each coordinate when the radio map is constructed.

The server 50 can receive the signal strength information from the mobile terminal 10 at the time of building the radio map, and calculate the relative magnitude ratio of the signal strength. Here, the relative magnitude ratio of the signal strength may be a value indicating a magnitude between signal intensities transmitted from a plurality of APs as a percentage. For example, if AP1, AP2, and AP3 are located indoors, the relative size ratio of signals transmitted from AP1 is 10%, the relative size ratio of signals transmitted from AP2 is 70% The size ratio can be 20%. Since the signal strength from the AP may vary due to environmental factors such as humidity and temperature as well as peripheral obstacles, defining the signal strength of the AP at a relative size ratio may reduce the influence of the surrounding environment on the signal strength.

The server 50 can form a radio map in which the coordinate information, the relative size ratio of the signal strength from the AP, and the reliability information are stored in the space.

Referring to FIG. 2, the signal strength received from the AP 1 at a specific location is a, the signal strength transmitted from the AP 2 is b, and the signal strength transmitted from the AP 3 is c. As will be described later, the relative magnitude ratio of signal strength between a: b: c can be calculated as 30%, 50%, and 20%. The coordinate information is (x, y) = (4, 4), and the reliability information of the coordinate is '1'.

When constructing the radio map, the server 50 divides the building space into grids, assigns coordinates, and constructs the radio map by considering signal information of the AP at each point corresponding to each coordinate.

The server 50 calculates information on the relative magnitude ratios of signal strengths of a plurality of APs for each coordinate, and constructs a multi-dimensional vector using the information. Multidimensional vectors can be sized according to the number of APs. The multidimensional vector may be a coordinate of a specific dimension of a relative magnitude ratio of signal strength of the AP. The server 50 may then classify and store the multidimensional vectors for fast radio map searches when estimating the location of the mobile terminal 10. [ The server 50 converts the multidimensional vector into a predetermined basic vector, e.g., [1,1,1 ... .1], and the coordinates can be classified and stored according to the cosine similarity. When the coordinates are classified using the cosine similarity degree, the calculation time can be reduced by comparing the cosine similarity first when estimating the position of the mobile terminal 10, and a detailed method will be described later.

The mobile terminal 10 and the server 50 can estimate the current position of the mobile terminal 10 using the radio map constructed by the above method. The mobile terminal 10 transmits to the server 50 information on signal strengths of a plurality of APs received at the corresponding location.

The server 50 calculates information on the relative magnitude ratio of the signal strength according to the signal strength information of a plurality of APs transmitted from the mobile terminal 10, and calculates a multidimensional vector using the relative magnitude ratio. The server 50 calculates the cosine similarity between the calculated multidimensional vector and the basic vector. The server 50 may compare the calculated cosine similarity with the previously stored cosine similarity, select a group corresponding to the calculated cosine similarity among the plurality of groups, and calculate the position using the Euclidean distance formula in the selected group.

When estimating the position of the mobile terminal 10, the server 50 can detect the walk of the pedestrian and use the information. The server 50 may set the stride in advance according to the gender and set the threshold of one step using the set stride information.

The server 50 estimates that one of the three axis values of the acceleration sensor included in the mobile terminal 10 has advanced one step when the value exceeds a certain threshold value. The server 50 can reduce the error by ignoring the change of the acceleration exceeding the predetermined maximum value in order to reduce the error. The server 50 ignores the step if a step is detected within the minimum time between steps.

3 is a control block diagram of a mobile terminal included in a location tracking system according to an embodiment of the present invention.

The mobile terminal 10 may include a wireless communication unit 12, a sensor unit 14, a memory unit 16, and a control unit 18.

The wireless communication unit 12 can measure the signal intensity from the neighboring AP. The wireless communication unit 12 can transmit the signal information to the server 50. [ The wireless communication unit 12 can implement normal wireless communication such as Wi-Fi and ZigBee.

The sensor unit 14 may include an acceleration sensor. The acceleration sensor can measure the movement acceleration of the mobile terminal 10. The acceleration sensor can measure the acceleration for three axes.

The memory unit 16 may store a program necessary for driving the mobile terminal 10.

The control unit 18 can control the server 50 to transmit the signal strength information of the AP measured through the wireless communication unit 12. [

FIG. 4 is a control block diagram of a server included in a location tracking system according to an embodiment of the present invention. FIG. 5 is a flowchart illustrating a method of generating a radio map performed by a location tracking system according to an embodiment of the present invention. FIG. 6 is a conceptual diagram for explaining a method of tracking a current location of a mobile terminal included in a location tracking system according to an embodiment of the present invention.

The server 50 may include a radio map generation unit 52, a database 54, a radio communication unit 56, and a location tracking unit 58.

The radio map generator 52 can construct a radio map using the signal strength information of each AP transmitted from the mobile terminal 10. The radio map generator 52 converts the signal intensity information of the AP for each coordinate into the relative magnitude ratio information of the signal intensity. And converts the signal strength from a plurality of APs of the coordinates to a relative percentage. For example, the relative percentage of the signal strength from AP1 to the corresponding coordinates may be converted to 20%, the relative percentage of signal strength from AP2 to 40%, and the relative percentage of signal strength from AP3 to 40%.

The radio map generator 52 generates a multidimensional vector according to the relative percentage of the signal strengths from the plurality of APs. For example, a multidimensional vector can be generated with [AP1, AP2, AP3] = [20, 40, 40].

The radio map generator 52 calculates the cosine similarity between the multidimensional vector and the predefined basic vector. For example, the multidimensional vector [20, 40, 40] and the basic vector [1, 1, 1] and the cosine similarity are calculated. The formula for calculating the cosine similarity between two vectors is shown in Equation 1.

Equation 1

The cosine similarity means a similarity between vectors measured using the cosine value between two vectors of inner space. When the angle is 0 °, the cosine value is 1 and the cosine value of all other angles is less than 1. Therefore, this value is used to determine the degree of similarity in directions other than the size of the vector. If the two vectors are completely the same, 1, Lt; / RTI >

The radio map generating unit 52 may group the coordinates according to the cosine similarity. The radio map generating unit 52 can be divided into, for example, a group of cosine similarity 0 to 0.2: 1, a group of cosine similarity 0.2 to 0.5: 2, and a group of cosine similarity 0.5 to 1: 3.

When all coordinates of the indoor are classified into a plurality of groups according to the degree of cosine similarity, when the position of the mobile terminal 10 is tracked, first, a group to which the corresponding coordinates belong is searched according to the degree of cosine of the mobile terminal 10, The coordinates matched to the position of the mobile terminal 10 can be calculated according to the distance formula. Applying the Euclidean distance formula can be used to determine the similarity of the signal strength by representing the physical distance between two vectors.

The radio map generator 52 may generate a radio map by matching information on the cosine similarity, the position coordinates, the reliability, and the like according to the coordinates. Referring to FIG. 5, the radio map generator 52 calculates an A vector according to a relative size ratio of the signal intensity of each AP transmitted from the mobile terminal 10, calculates a cosine similarity with a B vector, The degree of similarity of the cosine, the relative magnitude ratio information of the signal strength of the AP, coordinates of the coordinates, and reliability information may be stored in the database 54 to calculate and store the radio map.

The database 54 may store information about the radio map. As described above, the radio map information may include cosine similarity by coordinates, relative magnitude ratio information of AP signal intensity, coordinates of coordinates, and reliability information.

The database 54 may store information obtained by grouping a plurality of coordinates by the size of the cosine similarity. For example, a group having a cosine similarity of 0 to 0.5 may be stored as one group, and a group having a cosine similarity of 0.5 to 1 may be stored as two groups.

The wireless communication unit 56 can receive the signal strength information of the AP from the mobile terminal 10. The wireless communication unit 56 may transmit the location information of the mobile terminal 10 to the mobile terminal 10.

The location tracking unit 58 may track the location of the mobile terminal 10 using a radio map previously stored in the database 54. [ The location tracking unit 58 receives the signal strength information of the AP measured at the current location from the mobile terminal 10 through the wireless communication unit 12. [ The location tracking unit 58 calculates the relative size ratio of the AP signal strength according to the signal strength information of the AP. The location tracking unit 58 generates a multi-dimensional vector according to the relative magnitude ratio of the AP signal strength. The position tracking unit 58 calculates a cosine similarity by computing a multi-dimensional vector and a basic vector. The location tracking unit 58 calculates groups grouped by the degree of cosine similarity in the database 54 according to the calculated cosine similarity and applies the coordinates and the Euclidean distance formula belonging to the group to determine whether the mobile terminal 10 is in the current position Can be calculated. Referring to FIG. 6, the location tracking unit 58 calculates a multi-dimensional vector [30 .mu.] Using the signal strength information of AP1, AP2, and AP3 measured by the mobile terminal 10. And calculates the cosine similarity degree between the multidimensional vector [30, 50, 20] and the basic vector [1, 1, 1]. The cosine similarity is 0.16. The position tracking unit 58 may calculate the group to which the cosine similarity degree 0.16 belongs. For example, if a group of cosine similarities pre-stored in a radio map has a group of coordinates having a cosine similarity of 0 to 0.5 and a group having a cosine similarity of 0.5 to 1 are predefined as two groups, 1 group.

The position tracking unit 58 searches the coordinates having the most similar signal intensity information by applying the Euclidean distance formula to the currently measured signal intensity information using the information of the coordinates belonging to one group, And estimates the position.

7 is a control flowchart for explaining a radio map building method of a location tracking system according to an embodiment of the present invention.

The location tracking system 100 measures the signal strength of the AP for each coordinate, which is defined by dividing the space into a predetermined size, when the radio map is constructed. A plurality of APs may be installed in the corresponding space, and the mobile terminal 10 may measure the signal strength of the AP at all coordinates previously partitioned and transmit it to the server 50. (200)

The server 50 may calculate a multidimensional vector according to the signal strength of the AP. The multidimensional vector is a vector that is proportional to the number of APs and reflects the signal strength of the AP. (210)

The server 50 calculates a cosine similarity by computing a multidimensional vector and a predetermined basic vector. The cosine similarity means the similarity between the vectors measured using the cosine of the angle between two vectors of the inner space. (220)

The server 50 calculates the cosine similarity to the signal intensity of the AP measured at all the coordinates, and groups the plurality of coordinates according to the calculated cosine similarity. The grouping of the plurality of coordinates is performed by dividing a plurality of coordinates in a certain size range and classifying a plurality of coordinates in a plurality of groups according to the cosine similarity.

The server 50 can construct a radio map according to the cosine similarity of the coordinates belonging to the plurality of groups, the multidimensional vector, the coordinate information, and the reliability information. The reliability is an index indicating the reliability of the signal predetermined by the designer for each coordinate, and can be set in consideration of the surrounding obstacles and the measured values. For example, if the reliability is 0.5, it means that the reliability of the position estimation of the coordinates estimated according to the signal intensity of the AP is 50%. (240)

8 is a control flowchart for explaining a method of estimating a position of a position tracking system according to an embodiment of the present invention.

The mobile terminal 10 can measure the signal strength of the AP at the corresponding position. The signal strength of the AP may be measured as at least one signal strength from a plurality of APs. (300)

The mobile terminal 10 can transmit the signal intensity information of the AP measured at the corresponding point to the server 50. [ The mobile terminal 10 may transmit the signal strength information measured from a plurality of APs to the server 50. In step 310,

After receiving the signal strength information from the mobile terminal 10, the server 50 may generate a multidimensional vector using the information.

The server 50 calculates the cosine similarity between the multidimensional vector and a predetermined basic vector (330)

After calculating the cosine similarity, the server 50 selects a group on the radio map to which the calculated cosine similarity belongs (340)

The server 50 compares the signal strength information of the coordinates included in the selected group with the signal strength information of the measured coordinates to determine the degree of similarity and estimates the coordinates of the closest similarity as the position of the mobile terminal 10 .

A known Euclidean distance formula may be used to determine the similarity between signal strength information of a plurality of co-located APs included in a group and signal strength information of an AP at a location where the mobile terminal 10 is located.

The server 50 can track the user's own steps and update the current position after determining the initial position of the mobile terminal 10 by the above-described method. Any known method may be used for tracking the step. For example, when any one of the three-axis values of the acceleration sensor of the mobile terminal 10 exceeds a threshold value, a method of estimating the stepwise acceleration may be used . In this case, in order to reduce the error, a method of ignoring the detection of the step exceeding the minimum time between the step and the step can be used, ignoring the acceleration change value exceeding the predetermined distance in one step range. For reference, thresholds, distance ranges, time ranges, etc. used for step detection can be adjusted to suit all users' steps.

Such a radio map construction method and a user location estimation method may be implemented in an application or may be implemented in the form of program instructions that can be executed through various computer components and recorded in a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination.

The program instructions recorded on the computer-readable recording medium may be ones that are specially designed and configured for the present invention and are known and available to those skilled in the art of computer software.

Examples of computer-readable recording 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 floptical disks, media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for performing the processing according to the present invention, and vice versa.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. You will understand.

10: mobile terminal 50: server
52: radio map generator 54:
56: wireless communication unit 58: position tracking unit

Claims (10)

A mobile terminal for measuring signal strength information of an AP for each coordinate formed by dividing a space located in a building into a predetermined size; And
Receiving AP signal intensity information from the mobile terminal, converting signal intensity information of the AP into a relative magnitude ratio, converting the signal strength information into multi-dimensional vector information, calculating a cosine similarity between the multi-dimensional vector information and a predetermined basic vector, And a server for generating a radio map by grouping a plurality of coordinates located in the building according to the cosine similarity,
The server estimates the current position of the mobile terminal using the radio map, detects a user's step from the movement acceleration of the mobile terminal, sets a distance range corresponding to each step of the user, And determines a step of the user as a step if the movement acceleration of the mobile terminal is included between the threshold value and the maximum value, The moving speed of the mobile terminal is updated to reflect the current position of the mobile terminal. If the mobile acceleration of the mobile terminal is less than the threshold value or exceeds the maximum value, it is determined that the user has not moved in a unit of the distance range corresponding to the step width, Information between the user and the user is ignored, And if the step of the user is detected within a minimum time required for movement between the step and the step, the information is ignored. The method according to claim 1,
Wherein the mobile terminal transmits signal strength information of an AP measured for each of the coordinates and reliability information for each coordinate set by a designer to the server. delete The method according to claim 1,
The server estimates the current location of the mobile terminal,
Upon receiving the signal strength information of the AP from the mobile terminal when estimating the current position of the mobile station, a multidimensional vector is generated according to the signal strength information of the AP, and a cosine similarity between the multidimensional vector and a predetermined basic vector is calculated , A group grouped in the radio map is selected according to the calculated cosine similarity, and a physical distance between the multidimensional vector of the coordinates included in the group and the multidimensional vector of the position tracking object is calculated using the Euclidean distance formula in the group And estimates the coordinates of the closest distance as the current position of the mobile terminal as the location tracking target. delete Calculating a multidimensional vector by converting the signal strength information of the AP measured by the mobile terminal into a relative size ratio, calculating a cosine similarity between the multidimensional vector and a predetermined basic vector to group a plurality of coordinates,
Generates a radio map including coordinate information and relative magnitude ratio information of signal strengths from the APs for each of the plurality of grouped coordinates,
Calculating a multidimensional vector using the AP signal strength information transmitted from the mobile terminal to estimate a current position, calculating a cosine similarity with the base vector, selecting any one of the predetermined groups in the radio map, Estimating a current position of the mobile terminal in the selected group,
Detecting a user's step from the movement acceleration of the mobile terminal, setting a distance range corresponding to a stepwise stride for each user, calculating a moving acceleration of the mobile terminal corresponding to the distance range, setting a threshold value and a maximum value If the moving acceleration of the mobile terminal is included between the threshold value and the maximum value, it is determined that the user's step is one step, and the current position of the mobile terminal is updated by reflecting the corresponding information, If it is less than the threshold value or exceeds the maximum value, it is determined that the user has not moved in the distance range unit corresponding to the step width, and the corresponding information is ignored, and the minimum time required for the user to move between steps and steps So that the step of the user is performed between the step and the step When detected in a minimum amount of time that it takes the same time positioning method which ignores the information. delete The method according to claim 6,
Calculating a cosine similarity degree between the multidimensional vector and a predetermined basic vector to group a plurality of coordinates,
Dividing the size of the cosine similarity into a plurality of ranges, and grouping a plurality of coordinates by each range. The method according to claim 6,
Selecting one of the predetermined groups in the radio map and estimating the current position of the mobile terminal in the selected group,
A group of the cosine similarity calculated using the AP signal strength information transmitted from the mobile station is selected to estimate the current position, a multi-dimensional vector of the coordinates included in the selected group using the Euclidean distance formula, Calculating a physical distance between the multidimensional vectors, and estimating a coordinate of a closest distance as a current position of the mobile terminal as a target of the position tracking. A computer-readable recording medium having recorded thereon a computer program for executing the method for tracking a position according to any one of claims 6, 8, and 9.

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