Position specifying system and position specifying method

Abstract

To accurately specify a position of a wireless terminal in a short time even when there are two base stations.SOLUTION: In a position specifying system 10 of the present invention, a distance calculation device 11 calculates distances between base stations A, B and a wireless terminal T based on ta reception radio wave intensity of radio waves transmitted from the base stations A and B, a position estimation device 12 estimates two candidate positions of the wireless terminal T based on these distances and installation positions of the base stations A and B, and a position specifying device 13 transmits directional radio waves from the base station A or the base station B individually in a direction of these estimated positions, and specifies one of the two candidate positions as an existing position of the wireless terminal T based on whether the radio waves can be received by the wireless terminal T.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a location identification technology for identifying the location of a wireless terminal using radio waves. [Background technology]

[0002] Conventionally, a technology has been proposed for identifying the location of a wireless terminal using radio waves, in which the wireless terminal receives radio waves transmitted from each of a number of base stations installed in different locations, and identifies the location of the wireless terminal based on the received radio wave intensity of the radio waves.

[0003] For example, Patent Document 1 describes a technology in which a receiver (wireless terminal) receives radio waves transmitted from three transmitters (base stations) whose installation locations are known, measures the received signal strength indication (RSSI), calculates three distances from the receiver to each of the three transmitters based on the received signal strength obtained based on a preset relationship between the received signal strength and distance, and identifies the location of the receiver using a three-point positioning method based on the known installation locations of the three transmitters. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6740488 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional technology described in Patent Document 1, when determining the location of a receiver (wireless terminal) using radio waves, at least three transmitters (base stations) are required, which poses the problem that if there are only two transmitters around the receiver, the location of the receiver cannot be determined.

[0006] In addition, separate from the conventional technology described in Patent Document 1, a method can also be considered in which so-called beamforming technology is used to transmit radio waves, i.e., a beam signal, with increased directionality while changing the transmission direction, from a single base station, and the location of a wireless terminal is identified from the known installation location of the base station based on the transmission direction in which the beam signal was received by the wireless terminal and the distance to the base station calculated from the received electric field strength detected by the wireless terminal at that time.

[0007] However, with this method, because the transmission direction needs to be changed sequentially, it takes a certain amount of time before the location of the wireless terminal can be determined, and the more directivity is increased to improve the accuracy of determining the location, the more times the beam signal is transmitted, which increases the time required to determine the location.

[0008] The present invention is made to solve these problems, and aims to provide a location determination technology that can accurately determine the location of a wireless terminal in a short time even when there are two base stations. [Means for solving the problem]

[0009] In order to achieve such an object, the present invention provides a positioning system that identifies the position of a wireless terminal in a wireless system including first and second base stations that are installed at different positions and whose installation positions are known, and a wireless terminal that wirelessly communicates with the first and second base stations and measures the received radio wave intensity of radio waves transmitted from the first and second base stations, and that determines a first distance indicating a distance between the first base station and the wireless terminal and a distance between the second base station and the wireless terminal based on the received radio wave intensity of radio waves from the first and second base stations measured by the wireless terminal. a distance calculation device that calculates a first distance indicating a distance from the wireless terminal to the first base station and a second distance indicating a distance from the first base station to the second base station; a position estimation device that estimates two candidate positions where the wireless terminal is located based on the first and second distances calculated by the distance calculation device and position information indicating installation positions of the first and second base stations; and a position identification device that instructs at least one of the first base station and the second base station to transmit directional radio waves in the directions of the two candidate positions estimated by the position estimation device, and identifies one of the two candidate positions as the location of the wireless terminal based on whether the wireless terminal can receive the directional radio waves.

[0010] In one configuration example of the position specifying system according to the present invention, the position specifying device includes: The base station is configured to instruct one of the first base station and the second base station, which is closer to the wireless terminal, to transmit radio waves having the directionality.

[0011] In addition, in one configuration example of the positioning system according to the present invention, the positioning device is configured to instruct the first base station to transmit radio waves having the directionality in a direction toward one of the two candidate positions, and to instruct the second base station to transmit radio waves having the directionality in a direction toward the other of the two candidate positions.

[0012] A location identification method according to the present invention is a location identification method executed in a wireless system including first and second base stations installed at different positions and whose installation positions are known, and a wireless terminal that wirelessly communicates with the first and second base stations and measures received radio wave intensity of radio waves transmitted from the first and second base stations, The method includes a distance calculation step of calculating a first distance indicating the distance between the first base station and the wireless terminal and a second distance indicating the distance between the second base station and the wireless terminal based on the received radio wave strengths of radio waves from a first and a second base station measured by the wireless terminal; a position estimation step of estimating two candidate positions where the wireless terminal is located based on the first and second distances calculated in the distance calculation step and position information indicating the installation positions of the first and second base stations; and a position identification step of instructing at least one of the first base station and the second base station to transmit directional radio waves in the directions of the two candidate positions estimated in the position estimation step, and identifying one of the two candidate positions as the location of the wireless terminal based on whether the wireless terminal can receive the directional radio waves. Effect of the Invention

[0013] According to the present invention, even when there are two base stations, the location of a wireless terminal can be identified with high accuracy in a short time. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing a configuration of a location specifying system according to the present embodiment. [Diagram 2] FIG. 2 is an explanatory diagram showing a method of calculating the distance between a base station and a wireless terminal. [Diagram 3] FIG. 3 is an explanatory diagram showing a method of estimating two candidate positions where a wireless terminal exists. [Figure 4] FIG. 4 is a sequence diagram showing the operation of the position specifying system according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Next, an embodiment of the present invention will be described with reference to the drawings. [Location system] First, a location identification system 10 according to the present embodiment will be described with reference to Fig. 1. This location identification system 10 is connected to a wireless system 1 via a communication network NW such as the Internet, and is configured to identify the location of a wireless terminal T based on data obtained by base stations A and B (a first base station and a second base station) and a wireless terminal T in the wireless system 1.

[0016] The wireless system 1 is composed of a wireless communication system such as a general wireless LAN or a mobile communication system, and includes at least two base stations A and B installed at different known installation locations, and at least one wireless terminal T that performs wireless communication with each of the base stations A and B via wireless lines LA and LB.

[0017] The present invention is configured such that the location identification system 10 calculates the distance between base stations A, B and wireless terminal T based on the received radio wave strength of radio waves transmitted from base stations A, B, estimates two candidate locations where wireless terminal T is located based on this distance and the installation locations of base stations A, B, transmits directional radio waves from base station A or base station B individually in the direction of these estimated locations, and identifies one of the two candidate locations as the location of wireless terminal T based on whether or not the radio waves can be received by wireless terminal T.

[0018] [Location system configuration] Next, the configuration of the position specifying system 10 according to the present embodiment will be described with reference to FIG. As shown in Fig. 1, the position identification system 10 mainly comprises a distance calculation device 11, a position estimation device 12, and a position identification device 13. The distance calculation device 11, the position estimation device 12, and the position identification device 13 are each composed of a computer such as a server device, which are connected to each other so as to be able to communicate data with each other. In this case, any two or all of these devices may be configured to be shared by a single computer.

[0019] [Distance calculation device] Distance calculation device 11 is configured to calculate the distance between base station A and wireless terminal T and the distance between base station B and wireless terminal T based on the received radio wave intensity of radio waves from base stations A and B measured by wireless terminal T. The received radio wave intensity can be measured using radio waves such as beacon signals that are periodically transmitted from base stations A and B in a non-directional radiation pattern. This makes it possible to eliminate restrictions on the positional relationship between base stations A and B and wireless terminal T and on the measurement timing.

[0020] Here, a method for calculating the distance between the base stations A and B and the wireless terminal T will be described in detail with reference to FIG. Distances DA, DB (first distance, second distance) between base stations A, B and wireless terminal T can be calculated using the property that radio waves attenuate in proportion to the square of the distance. If the reference radio wave strength indicating the received radio wave strength at a reference distance of 1 m for radio waves SA, SB transmitted from base stations A, B is R1, the relationship between the received electric field strength RA of radio wave SA transmitted from base station A at wireless terminal T and distance DA is expressed by the following formula (1). RA = R1-2 × 10 × log 10 D A …(1)

[0021] Similarly, the relationship between the received electric field strength RB of radio waves SB transmitted from a base station B at a wireless terminal T and the distance DB is expressed by the following equation (2). RB = R1-2 × 10 × log 10 DB…(2) Therefore, if the received electric field strengths RA and RB are measured at the wireless terminal T, the distances DA and DB from the base stations A and B to the wireless terminal T can be calculated based on the above equations (1) and (2).

[0022] [Position estimation device] The position estimation device 12 is configured to estimate two candidate positions where the wireless terminal T exists, based on the two distances calculated by the distance calculation device 11 and position information indicating the installation positions of the base stations A and B. The position information of the base stations A and B may be registered in advance in a storage device of the position estimation device 12, or may be acquired from the base stations A and B or an external database via the communication network NW.

[0023] Here, a method for estimating two candidate positions where the wireless terminal T exists will be described in detail with reference to FIG. Based on the distances DA, DB from base stations A, B to wireless terminal T calculated by distance calculation device 11, wireless terminal T is located at a position that is the distance DA away from base station A and at a position that is the distance DB away from base station B. Therefore, wireless terminal T is located at the intersection of two circles CA, CB that have the distances DA, DB as radii and have base stations A, B as centers, respectively.

[0024] If the distances DA and DB are not equal, the circles CA and CB intersect at two intersections P1 and P2, meaning that the wireless terminal T is located at one of these intersections, but it is not possible to specify at which of the intersections P1 and P2 the wireless terminal T is located based on the distances DA and DB alone. For this reason, these intersections P1 and P2 are estimated as candidate positions P1 and P2 of the wireless terminal T. At this time, the installation positions PA and PB of the base stations A and B are known as coordinate data in a reference coordinate system such as the Global Positioning System (GPS), for example, so that two equations indicating the circles CA and CB with radii DA and DB centered on the base stations A and B are set as simultaneous equations, and the solution is obtained to determine the coordinate data of the candidate positions P1 and P2.

[0025] [Location device] The position identification device 13 is configured to individually transmit beam signals S1, S2 using directional radio waves, i.e., a beamforming pattern, from base station A or base station B in the directions of the two candidate positions P1, P2 estimated by the position estimation device 12, and to identify one of the two candidate positions P1, P2 as the location P of the wireless terminal T based on whether the beam signals S1, S2 are received by the wireless terminal T.

[0026] As a technology for transmitting the beam signals S1 and S2 in a beamforming pattern, a well-known technology using a phased array antenna, for example, a technology that has been put into practical use in wireless LAN and a 5th generation mobile communication system (5G), may be used.

[0027] Here, a method for identifying the location P of the wireless terminal T based on the candidate locations P1 and P2 will be described in detail with reference to Fig. 3 mentioned above. In the following, an example will be described in which the beam signals S1 and S2 are transmitted from the base station A, but either the base station A or the base station B may be selected as the base station that transmits the beam signals S1 and S2. It is also possible to transmit the beam signals S1 and S2 from both the base station A and the base station B, and identify the location of the wireless terminal T based on whether the beam signals S1 and S2 transmitted from one of the base stations can be received.

[0028] When transmitting beam signals S1, S2 from base station A in the direction of candidate positions P1, P2 of wireless terminal T estimated by position estimation device 12, it is necessary to specify the transmission direction. At this time, since the installation locations PA, PB of base stations A, B are known, the transmission angles Θ1, Θ2 from the direction of base station B to candidate positions P1, P2 at base station A can be calculated from the installation locations PA, PB and candidate positions P1, P2 in the reference coordinate system.

[0029] Based on these transmission angles Θ1 and Θ2, beam signals S1 and S2 are transmitted from base station A to candidate positions P1 and P2, respectively, and the location of wireless terminal T is identified based on whether or not wireless terminal T can receive beam signals S1 and S2. In the example of Fig. 3, since wireless terminal T is located at candidate position P1, wireless terminal T can receive beam signal S1 but cannot receive beam signal S2. As a result, the location of wireless terminal T is identified as P1.

[0030] In the above, the distance calculation device 11, the position estimation device 12, and the position determination device 13 constituting the position determination system 10 are described as being separate devices from the base stations A and B and the wireless terminal T, but the present invention is not limited to this. Any one or more of these devices may be configured as a control circuit mounted on the base stations A and B or the wireless terminal T, and for example, the distance calculation device 11 may be configured as a control circuit of the base stations A and B or the wireless terminal T.

[0031] In this case, if distance calculation device 11 that calculates distance DA is realized in the control circuit of base station A, and distance calculation device 11 that calculates distance DB is realized in the control circuit of base station B, it will be necessary for each base station A and B to store parameters specific to each base station A, B, such as reference field strength R1, and the accuracy of the distance calculation can be improved while reducing the burden of managing parameters required for distance calculation.

[0032] [Operation of this embodiment] Next, the operation of the position specifying system 10 according to the present embodiment will be described with reference to FIG.

[0033] When the wireless terminal T receives a radio wave SA transmitted from the base station A (step 100), it measures the received radio wave intensity RA (step 101) and notifies the base station A of the measurement result indicating the obtained received radio wave intensity RA via the wireless line LA based on the transmission source information extracted from the radio wave SA (step 102). The base station A notifies the distance calculation device 11 of the measurement result from the wireless terminal T via the communication network NW (step 103).

[0034] Based on the received radio wave strength RA obtained at the wireless terminal T included in the measurement result from the base station A and the location information indicating the installation location PA of the base station A, the distance calculation device 11 calculates the distance DA between the base station A and the wireless terminal T using the calculation method for the distances DA, DB between the base stations A, B and the wireless terminal T shown in Figure 2 above (step 104), and notifies the location estimation device 12 of the obtained distance DA (step 105).

[0035] Furthermore, when the wireless terminal T receives radio waves SB transmitted from the base station B (step 110), it measures the received radio wave strength RB (step 111) and notifies the base station B of the measurement result indicating the obtained received radio wave strength RB via the wireless line LB based on the transmission source information extracted from the radio waves SB (step 112). The base station B notifies the distance calculation device 11 of the measurement result from the wireless terminal T via the communication network NW (step 113).

[0036] Based on the received radio wave strength RB obtained at the wireless terminal T included in the measurement result from the base station B and the location information indicating the installation location PB of the base station B, the distance calculation device 11 calculates the distance DB between the base station B and the wireless terminal T using the calculation method for the distances DA, DB between the base stations A, B and the wireless terminal T shown in Figure 2 above (step 114), and notifies the location estimation device 12 of the obtained distance DB as the calculation result (step 115).

[0037] Based on the distances DA, DB notified by the distance calculation device 11 and the location information indicating the installation positions PA, PB of the base stations A, B, the location estimation device 12 estimates two candidate positions P1, P2 where the wireless terminal T is located by the estimation method for two candidate positions where the wireless terminal T is located shown in Figure 3 above (step 120), and notifies the position identification device 13 of the obtained candidate positions P1, P2 as the estimation results (step 121).

[0038] Based on the estimated positions P1, P2 notified by the position estimation device 12 and the position information indicating the installation position PA of the base station A, the position identification device 13 calculates the transmission angles Θ1, Θ2 indicating the directions of the candidate positions P1, P2 at the base station A by the method of identifying the location P of the wireless terminal T based on the candidate positions P1, P2 shown in Figure 3 above (step 122). Next, the position specifying device 13 notifies the base station A of a beam transmission instruction including the obtained transmission angles Θ1, Θ2 via the communication network NW (step 123).

[0039] In response to a beam transmission instruction from the position identification device 13, the base station A transmits a beam signal S1 in a directional radio wave, i.e., a beam forming pattern, in the direction of the specified transmission angle Θ1 (step 124). Also, the base station A transmits a beam signal S2 in a directional radio wave, i.e., a beam forming pattern, in the direction of the specified transmission angle Θ2 (step 125).

[0040] When the wireless terminal T receives either the beam signal S1 or S2 transmitted from the base station A, the wireless terminal T notifies the base station A of the reception result indicating the received beam signal S1 or S2 via the wireless line LA based on the transmission source information extracted from the beam signal S1 or S2 (step 126). The base station A notifies the position determination device 13 of the reception result from the wireless terminal T via the communication network NW (step 127).

[0041] Based on the reception results of the beam signals S1 and S2 from the wireless terminal T, the position identifying device 13 identifies one of the candidate positions P1 and P2 as the location P of the wireless terminal T (step 128), and ends the sequence of position identifying processing.

[0042] Therefore, for example, if wireless terminal T is present at candidate position P1, then wireless terminal T will be able to receive beam signal S1 but will not be able to receive beam signal S2. As a result, wireless terminal T will notify position identifying device 13 via base station A of a reception result indicating that beam signal S1 can be received, and position identifying device 13 will identify candidate position P1 corresponding to beam signal S1 as the location P of wireless terminal T.

[0043] [Advantages of this embodiment] In this manner, the position determination system 10 according to this embodiment is configured such that the distance calculation device 11 calculates the distances DA, DB between the base stations A, B and the wireless terminal T based on the received radio wave intensities RA, RB of the radio waves SA, SB transmitted from the base stations A, B, the position estimation device 12 estimates two candidate positions P1, P2 where the wireless terminal T is located based on these distances DA, DB and the installation positions PA, PB of the base stations A, B, and the position determination device 13 individually transmits directional radio waves, i.e., beam signals S1, S2, from the base station A or base station B in the direction of these estimated positions P1, P2, and identifies one of the two candidate positions P1, P2 as the location P where the wireless terminal T is located based on whether the wireless terminal T can receive these beam signals S1, S2.

[0044] As a result, when there are two base stations A and B capable of wireless communication with wireless terminal T, only candidate positions P1 and P2 of wireless terminal T can be estimated from the distances DA and DB between base stations A and B and wireless terminal T, but based on directional beam signals S1 and S2, one of candidate positions P1 and P2 will be identified as the location P of wireless terminal T.

[0045] Therefore, even if there are two base stations A and B capable of wireless communication with the wireless terminal T, it is possible to accurately identify the location P of the wireless terminal T. Also, since it is only necessary to transmit the beam signals S1 and S2 toward the two candidate positions P1 and P2, respectively, it is possible to identify the location P of the wireless terminal T in a short time compared to, for example, the case where the beam signal is transmitted from the base station A over the entire circumference.

[0046] [Extended embodiment] Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above embodiment. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0047] In the above embodiment, it was explained that either base station A or B may be selected as the base station for transmitting the beam signals S1 and S2, but this is not limited to this, and the beam signals S1 and S2 may be transmitted from one of base stations A and B that is closer to the wireless terminal T.

[0048] For example, the position determination device 13 selects one of base stations A and B which has the shorter distance DA, DB from the wireless terminal T, calculates the transmission angles Θ1, Θ2 to the candidate positions P1, P2 at that base station, and notifies the base station of a beam transmission instruction including these transmission angles Θ1, Θ2.

[0049] As a result, the beam signals S1 and S2 are transmitted from a base station closer to the wireless terminal T, so that the beam signals S1 and S2 can be received by the wireless terminal T more reliably.

[0050] In addition, in the above-mentioned embodiment, an example was described in which the beam signals S1 and S2 are transmitted from either one of the base stations A and B, but this is not limited to this, and the beam signals S1 and S2 may be transmitted separately from base stations A and B, respectively.

[0051] For example, the position determination device 13 may calculate a transmission angle Θ1 to a candidate position P1 at base station A, notify base station A of a beam transmission instruction including the transmission angle Θ1, calculate a transmission angle Θ2 to a candidate position P2 at base station B, and notify base station B of a beam transmission instruction including the transmission angle Θ2.

[0052] As a result, a beam signal S1 is transmitted from base station A in the direction of candidate position P1, and a beam signal S2 is transmitted from base station B in the direction of candidate position P2. When wireless terminal T receives beam signal S1 transmitted from base station A, it notifies base station A of a reception result indicating the received beam signal S1 via wireless line LA based on the transmission source information extracted from the beam signal S1. Base station A notifies the position identification device 13 of the reception result from wireless terminal T via communication network NW.

[0053] Furthermore, when the wireless terminal T receives the beam signal S2 transmitted from the base station B, the wireless terminal T notifies the base station B of the reception result indicating the received beam signal S2 via the wireless line LB based on the transmission source information extracted from the beam signal S2. The base station B notifies the position identification device 13 of the reception result from the wireless terminal T via the communication network NW.

[0054] As a result, the location identification device 13 is notified of a reception result indicating that beam signals S1, S2 can be received from either base station A or B, and based on that reception result, either one of the candidate positions P1, P2 is identified as the location P of the wireless terminal T.

[0055] Therefore, the processing operation of transmitting a beam signal to the wireless terminal T can be distributed to multiple base stations rather than being concentrated in one base station. This allows the resources in the wireless system 1 to be used efficiently, and makes it possible to suppress the influence of resource imbalance on wireless communication in the wireless system 1. [Explanation of symbols]

[0056] 10...location determination system, 11...distance calculation device, 12...location estimation device, 13...location determination device, 1...wireless system, A...base station, B...base station, T...wireless terminal, W...communication network, SA, SB...radio waves, RA, RB...received field strength, DA, DB...distance, PA, PB...installation location, P...existence location, Θ1, Θ2...transmission angle, S1, S2...beam signal.

Claims

1. A position identification system for identifying a position of a wireless terminal in a wireless system including first and second base stations installed at different positions and whose installation positions are known, and a wireless terminal that wirelessly communicates with the first and second base stations and measures received radio wave intensity of radio waves transmitted from the first and second base stations, comprising: a distance calculation device that calculates a first distance indicating a distance between the first base station and the wireless terminal and a second distance indicating a distance between the second base station and the wireless terminal based on received radio wave strengths of radio waves from a first and a second base station measured by the wireless terminal; a position estimation device that estimates two candidate positions where the wireless terminal is located based on the first and second distances calculated by the distance calculation device and position information indicating installation positions of the first and second base stations; a location identification device that instructs at least one of the first base station and the second base station to transmit directional radio waves in the directions of the two candidate locations estimated by the location estimation device, and identifies one of the two candidate locations as the location of the wireless terminal based on whether the wireless terminal can receive the directional radio waves; A location determination system comprising:

2. The location identification device is a base station that is closer to the wireless terminal than the first base station or the second base station is configured to instruct the base station to transmit the directional radio wave. The location system of claim 1 .

3. The location identification device is The first base station is configured to instruct the first base station to transmit radio waves having the directivity in a direction toward one of the two candidate positions, and to instruct the second base station to transmit radio waves having the directivity in a direction toward the other of the two candidate positions. The location system of claim 1 .

4. A location identification method executed in a wireless system including first and second base stations installed at different positions and whose installation positions are known, and a wireless terminal that wirelessly communicates with the first and second base stations and measures received radio wave intensity of radio waves transmitted from the first and second base stations, comprising: a distance calculation step of calculating a first distance indicating a distance between the first base station and the wireless terminal and a second distance indicating a distance between the second base station and the wireless terminal based on received radio wave intensities of radio waves from a first and a second base station measured by the wireless terminal; a position estimating step of estimating two candidate positions where the wireless terminal is present, based on the first and second distances calculated in the distance calculating step and position information indicating installation positions of the first and second base stations; a location specifying step of instructing at least one of the first base station and the second base station to transmit directional radio waves in the directions of the two candidate locations estimated in the location estimating step, and specifying one of the two candidate locations as the location of the wireless terminal based on whether the wireless terminal can receive the directional radio waves; A location determination method comprising:

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