JP2009065301A - Current location positioning calculating method of mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current location positioning calculating method of a mobile communication terminal for measuring the current location of a PHS terminal and a mobile communication terminal such as a portable telephone terminal with high accuracy by using the electric field intensity of a fixed base station. <P>SOLUTION: In the current location positioning calculating method of a mobile communication terminal for calculating the current location of a mobile communication terminal by measuring electric field intensity issued by a fixed base station comprising a transmitting and receiving means, a method of least squares is used, which defines such a point at which a difference between the total amounts of ranges from the mobile communication terminal and respective base stations which are calculated on the basis of measured electric field intensity of the respective base stations whose radio waves can be measured by the mobile communication terminal, and the total amounts of ranges from the calculated point and the respective base stations, becomes minimum, as the current location. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for calculating the current position of a mobile communication terminal that measures the position of a mobile communication terminal such as a PHS terminal or a mobile phone terminal with high accuracy using the electric field strength of a fixed base station.

  In communication using a mobile communication terminal such as a PHS terminal or a mobile phone terminal, the mobile communication terminal is connected to an existing public telephone network via a base station that covers an area where the mobile communication terminal is located. Connected. At this time, the mobile communication terminal is connected to a base station in an area where the mobile communication terminal is located among base stations installed in a number of areas, that is, via a base station closest to the mobile communication terminal. Connected to public telephone network.

The mobile communication terminal stores the reception level of radio waves of neighboring base stations when waiting, and selects the base station having the maximum reception level for communication. That is, the reception level of the radio waves of the base stations in the vicinity of the mobile communication terminal is stored in the mobile communication terminal together with the base station identification code, referring to the database having the base station identification code and geographical location information, The following patent document discloses that the current position of a mobile communication terminal can be specified by performing calculation using the radio wave reception level of a base station and geographical position information.
Japanese Patent Laid-Open No. 2-44929

  In recent years, position information providing services based on position detection of mobile communication terminals such as PHS terminals and mobile phone terminals have rapidly spread. This kind of position detection method using the relationship between the base station and the mobile communication terminal is inferior to the position information detection method using the GPS terminal, but the position information accuracy is inferior in the building where GPS radio waves do not reach. It has the advantage that it can also be used in subways and subways, and is beginning to be used as a useful method for reducing power consumption and narrowing down the approximate location.

  However, in the above-described conventional position detection method using a mobile communication terminal, the error may be several hundred m to several tens km depending on the reception level of the base station radio wave of the mobile communication terminal. For example, in the location information service by PHS, there are many regions including location calculation errors of several hundred meters to several kilometers.

  This is because the position of the mobile communication terminal calculated from a plurality of received electric field values received by the mobile communication terminal when the radio wave reaching the mobile communication terminal from the base station is attenuated by an obstacle or the like on the transmission path This is because the position of the actual mobile communication terminal is shifted and it is difficult to detect the accurate position.

  The object of the present invention is to dramatically improve the accuracy of the means for identifying the position of the mobile communication terminal using the radio wave level of the peripheral base station acquired by the mobile communication terminal, Providing a method for calculating the current position of a mobile communication terminal suitable for searching for elderly people and missing persons, searching for stolen goods, or searching for victims who underlayed a building when a house collapsed due to an earthquake There is.

  The configuration of the present invention for achieving the above object will be described in detail. The invention according to claim 1 determines the current position of the mobile communication terminal by measuring the electric field intensity emitted from the fixed base station having the transmitting / receiving means. In the location search method of the mobile communication terminal, the total distance from the mobile communication terminal to each base station calculated from the measured electric field strength of each base station at which the mobile communication terminal can measure radio waves, and the calculation point This is a method for calculating the current position of a mobile communication terminal using the least square method, characterized in that a point where the difference between the distance from the base station and the total distance from each base station is the smallest is the current position.

  According to a second aspect of the present invention, there is provided a mobile communication terminal position search method for determining a current position of a mobile communication terminal by measuring an electric field intensity generated by a fixed base station having a transmission / reception means. Measured by reducing the difference between the distance from the mobile communication terminal to each base station calculated from the measured field strength of each base station that can be measured, and the distance between the calculation point and each base station. The current mobile communication terminal using the least-squares method, characterized in that the distance from the mobile communication terminal to each base station calculated from the electric field strength is calculated based on the electric field strength of the base station with the largest electric field strength. This is a positioning calculation method.

  According to a third aspect of the present invention, there is provided a mobile communication terminal position search method for determining a current position of a mobile communication terminal by measuring an electric field intensity generated by a fixed base station having a transmission / reception means. The position of each base station that can be measured is the mass point, and the center of gravity when the measured electric field strength of each base station is the mass at the mass point corresponding to each base station is the current position of the mobile communication terminal. This is a method for calculating the current position of a mobile communication terminal.

  Furthermore, the invention according to claim 4 is configured such that, for the positioning calculation result based on the calculation method according to claim 3, the calculation result when the mass of each mass point is set to 1 and the point symmetrical to the point of the mobile communication terminal. This is a method for calculating the current position of a mobile communication terminal, characterized in that it is the current position.

  When the electric field strength of the base station radio wave measured by the mobile communication terminal is E and the distance from the mobile communication terminal to the base station is D, E and D are in an inversely proportional relationship, and E = k / D Can do. Here, k is a proportional constant and takes different values depending on the type of transmission / reception equipment attached to the mobile communication terminal and the base station, the installation environment, etc., but obtaining information for determining k at the time of measurement is obtained. Often difficult.

  In addition, due to the influence of obstacles on the transmission path between the base station and the mobile communication terminal, the above relationship between E and D may not be established depending on the radio wave of the base station to be measured. The distance calculated from includes an error. Based on this, the method of calculating the position of the mobile communication terminal using the least square method focusing on the relationship between E and D on the xy coordinates as in claim 1 is as follows: This is a calculation method in which a point (X, Y) that minimizes Equation 1] is used as a calculation result.

  Here, xi and yi are the x-coordinate and y-coordinate of the base station of base station number i, ri is the distance between the base station of base station number i calculated from the electric field strength and the mobile communication terminal, and a is k The proportionality constant based on, n is the number of base stations used in the calculation. By obtaining X, Y, a that minimizes the value of this expression, the point (X, Y) of the current position of the mobile communication terminal can be obtained.

  As described above, a is a value that changes each time it is measured. However, since it is difficult to specify a variation factor, the optimization by the least square method may be a value that differs greatly from the correct value. Therefore, as in claim 2, that is, the value of the distance from the mobile communication terminal to each base station calculated from the measured electric field strength of each base station at which the mobile communication terminal can measure radio waves, and the calculation Reduce the difference in the distance value between the point and each base station, so that [Equation 1] does not have a large difference in the value of each term calculated from the distance between each base station and the mobile communication terminal. Also, the proportionality constant a between the distance and the reciprocal of the electric field strength is calculated by using the characteristic of the base station that has the strongest electric field strength that is considered to have the smallest error. By applying multiplication and obtaining X and Y that minimize the value of the expression, the coordinates (X, Y) of the location of the current position of the mobile communication terminal can be obtained, and a is not optimized. Accurate calculation results can be obtained.

  FIG. 1 shows that the method of claim 2 has better calculation accuracy than the method of claim 1 for the positioning calculation method using these two types of least squares methods. The graph 1 in FIG. 1 represents the result by the method of claim 1, and the graph 2 represents the result by the method of claim 2.

  FIG. 1 is an analysis of actual positioning calculation results using mobile communication terminals and fixed base stations at multiple points, and summarizes the accuracy of each. The vertical axis indicates positioning calculation errors, and the horizontal axis indicates mobile communication terminals. It represents the average distance between neighboring base stations, and the scale of each axis of the two graphs is the same. The area below the oblique line 3 includes 80% of the calculation result of the graph. The smaller the inclination of the oblique line 3, the better the accuracy of the calculation method.

  Furthermore, in areas with many buildings such as urban areas and business districts, reception of base station radio waves by mobile communication terminals is likely to cause radio wave interruption and multipath, and there is almost no correlation between measured electric field strength and distance. There is a case. At this time, the surrounding base stations from which the mobile communication terminal obtains the electric field strength are often randomly selected around the terminal, and in this case, the mobile communication terminal is Calculation of the position of the center of gravity as the position of the mobile communication terminal, where the position of each measurable base station is the mass point and the measured electric field strength of each base station is the mass at the mass point corresponding to each base station By using this method, the positioning calculation accuracy can be increased.

  When the above-mentioned center of gravity calculation is used for the position detection means of the mobile communication terminal in two dimensions, each base station is on the same circumference, and there are two or more symmetry axes connecting the center of the circle and each base station. Or when a line connecting the center of a circle and each base station is extended on the circumference and there are two or more symmetry axes connecting the center of the circle and each base station, the position of the mobile communication terminal is Calculated in the center.

  That is, when the base stations used for calculating the position of the mobile communication terminal are arranged at equal intervals around the terminal, the calculation result matches the actual position of the mobile communication terminal. In urban areas and business districts, base station installation intervals are also narrow, and base stations where mobile communication terminals measure radio waves are often selected at approximately equal intervals around the terminals. By specifying the position of the terminal, the positioning calculation accuracy can be increased. In addition, although the above least squares method repeats the calculation many times in order to derive the calculation result, the calculation of the center of gravity can be shortened because the calculation is completed by executing a simple calculation once. .

  In addition, when there are two or more base stations with strong electric field strength measured by the mobile communication terminal, or when the field strength measurement value of the base station located far from the mobile communication terminal is large, positioning calculation is performed. The resulting position is shifted in the direction of the base station. In this case, as in claim 4, with respect to the positioning calculation result of claim 3, the calculation result when the mass of each mass point is set to 1 by the positioning calculation method of claim 3 and the point-symmetric point are moved. By using the positioning calculation method as the current position of the communication terminal, the positioning calculation result by the centroid calculation is corrected.

  FIG. 2 shows that the method of claim 4 has better calculation accuracy than the method of claim 3 for the positioning calculation method using these two types of centroid calculations. The graph 4 in FIG. 2 represents the result by the method of claim 3, and the graph 5 represents the result by the method of claim 4.

  FIG. 2 is an analysis of actual positioning calculation results using mobile communication terminals and fixed base stations at multiple points, and summarizes the accuracy of each. The vertical axis is the positioning calculation error, and the horizontal axis is the mobile communication terminal. It represents the average distance between neighboring base stations, and the scale of each axis of the two graphs is the same. The area below the oblique line 6 includes 80% of the graph calculation result, and the smaller the inclination of the oblique line 6, the better the accuracy of the calculation method.

  As described above, according to the present invention, in the method for identifying the position of the mobile communication terminal using the electric field strength of the peripheral base station acquired by the mobile communication terminal, the accuracy can be dramatically improved. The current mobile communication terminal is suitable for searching for unknown logistics cargo, searching for elderly people and missing persons, searching for stolen goods, or searching for victims who underlayed a building when a house collapsed due to an earthquake. A position measurement calculation method can be provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a current position positioning calculation method for a mobile communication terminal according to the present invention will be described with reference to the drawings.

  3 is a conceptual diagram of a positioning system using a mobile communication terminal, FIG. 4 is an explanatory diagram of a positioning calculation method using a least square method, and FIG. 5 is an explanatory diagram of a positioning calculation method using centroid calculation.

  In FIG. 3, reference numeral 7 denotes a PHS terminal as a mobile communication terminal, and the PHS terminal 7 is connected to an existing public telephone line network (PHS network) 9 through a base station 8, and through the public telephone line network 9. Communication with other mobile communication terminals or various networks is possible.

  The mobile communication terminal 7 holds base station information at a plurality of places that can be transmitted and received, and has base station numbers of the plurality of base stations 8 and electric field strength information with respect to them.

  In the present embodiment, the information is transmitted to the server 10 using the public telephone line network 9, the base station position corresponding to the base station number transmitted by the base station position database 11 in the server 10 is specified, The position calculation program (positioning algorithm) 12 in the server 10 calculates the position of the mobile communication terminal 7. The calculation result can be confirmed with a general-purpose information communication terminal via the Internet.

  The positioning calculation method performed by using the position of the base station and the electric field strength acquired by the position calculation server 10 from the mobile communication terminal 7 in FIG. 3 will be described with reference to FIG. Here, the mobile communication terminal 7 receives radio waves transmitted from the base stations 1, 2, 3, and 4, and the distance from each base station 1, 2, 3, and 4 calculated from the received electric field strength. Are r1, r2, r3, r4. The coordinates of the positions of the base stations 1, 2, 3, and 4 on the xy coordinates are (x1, y1), (x2, y2), (x3, y3), and (x4, y4), respectively.

  According to the positioning calculation method of claim 2, the position of the mobile communication terminal on the xy coordinate is calculated on a point (X, Y) that minimizes the following equation [Equation 2].

  In an area where the base station density is high, the calculation method of claim 3 is switched. The calculation method is a method in which the coordinates (X, Y) of the points on the xy coordinates calculated by the following equation [Equation 3] are used as positioning results in the arrangement of the base station and the mobile communication terminal.

In this equation [Equation 3], m is the measured electric field strength of each base station. In an area where accuracy is extremely poor when calculated by this method, the positioning calculation method described in claim 4 is particularly effective. That is, in the arrangement of the base station and mobile communication terminal in FIG.
With respect to the positioning calculation result 22 of [Equation 3], the coordinate 23 of a point that is point-symmetric with the calculation result 21 of the following equation [Equation 4] is used as the current position of the mobile communication terminal.

  As described above, according to the current position positioning calculation method of the mobile communication terminal of the present invention, the characteristics of the types of the mobile communication terminal and the base station, the base station radio wave due to the building between the mobile communication terminal and the base station, etc. It is possible to accurately determine the current position of the mobile communication terminal without depending on the change in the propagation characteristics of the mobile communication terminal.

It is a graph showing the precision of a positioning calculation result. It is a graph showing the precision of a positioning calculation result. It is a conceptual diagram of the positioning system using a mobile communication terminal. It is explanatory drawing of the positioning calculation method using the least squares method. It is explanatory drawing of the positioning calculation method using a gravity center calculation.

Explanation of symbols

7: Mobile communication terminal 8: Base station 9: Public telephone network 10: Location calculation server 11: Base station location database 12: Location calculation program (positioning algorithm)

Claims (4)

  In the mobile communication terminal position search method for determining the current position of the mobile communication terminal by measuring the electric field intensity emitted by the fixed base station equipped with the transmission / reception means, the mobile communication terminal of each base station capable of measuring radio waves The position where the difference between the total distance from the mobile communication terminal calculated from the measured electric field strength to each base station and the total distance between the calculated point and each base station is the smallest is the current position. A method for calculating the current position of a mobile communication terminal using the least squares method.   In the mobile communication terminal position search method for determining the current position of the mobile communication terminal by measuring the electric field intensity emitted by the fixed base station equipped with the transmission / reception means, the mobile communication terminal of each base station capable of measuring radio waves Mobile communication that reduces the difference between the distance from the mobile communication terminal calculated from the measured electric field strength to each base station and the difference between the calculation point and each base station, and calculates from the measured electric field strength A method for calculating the current position of a mobile communication terminal using a least square method, characterized in that a distance from a terminal to each base station is calculated based on the electric field strength of a base station having the largest electric field strength.   In a mobile communication terminal position search method for determining the current position of a mobile communication terminal by measuring an electric field intensity generated by a fixed base station equipped with a transmission / reception means, the position of each base station that can be measured by the mobile communication terminal is determined. The current position of the mobile communication terminal is defined as the current position of the mobile communication terminal, where the point of gravity is the mass point and the measured electric field strength of each base station is the mass at the mass point corresponding to each base station. Positioning calculation method.   A movement characterized in that, for the positioning calculation result based on the calculation method according to claim 3, a point symmetric with the calculation result when the mass of each mass point is 1 is the current position of the mobile communication terminal. A method for calculating the current position of a body communication terminal.

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