JP7515127B2 - Estimation system, estimation method, and program - Google Patents

Description

The present disclosure relates to an estimation system, an estimation method and a program, and more particularly to an estimation system, an estimation method and a program having multiple antennas.

Patent document 1 describes a communication terminal device that estimates the direction of arrival of a beacon signal (radio signal). The communication terminal device (receiver) described in patent document 1 estimates the direction of arrival of a beacon signal transmitted by a beacon device (transmitter) based on the signal strength (RSSI: Received Signal Strength Indicator) of the radio signal received by multiple antennas.

However, with the receiver described in Patent Document 1, a plurality of receivers (for example, four receivers) are required to estimate the transmission position of a wireless signal.

The present disclosure has been made in consideration of the above reasons, and aims to provide an estimation system, estimation method, and program that can reduce the number of antennas when estimating the position of a target device.

In order to solve the above problem, an estimation system according to an aspect of the present disclosure includes a receiver, an estimation unit, a first storage unit, and a second storage unit. The receiver has a plurality of antennas. The plurality of antennas receive radio signals transmitted from a transmitter. The receiver performs phase synthesis processing on the radio signals received by the plurality of antennas to generate a plurality of synthetic signals. The estimation unit estimates the position of the transmitter within a predetermined area. The first storage unit stores a plurality of pieces of position information. The plurality of pieces of position information indicate a plurality of positions at a plurality of candidate points for estimating the position of the transmitter. The second storage unit stores a plurality of quasi-theoretical values. The plurality of quasi-theoretical values correspond one-to-one to each of the plurality of candidate points. The plurality of quasi-theoretical values are values related to direct waves and reflected waves received by the receiver when a radio signal is transmitted at each of the plurality of candidate points. The estimation unit estimates the position of the transmitter within the predetermined area based on the plurality of pieces of position information, the plurality of quasi-theoretical values, and a plurality of signal intensities in the plurality of synthetic signals. A reference transmitter that transmits a reference signal is disposed within the predetermined area, and a virtual point is set based on location information indicating the location of the receiver, location information indicating the location of the reference transmitter, and a signal strength when the reference signal is received by the receiver. The virtual point is a virtual reception point that is located opposite the reference transmitter via a reflector that reflects the reference signal, and can be considered to have received the reference signal in the absence of the reflector, or a virtual transmission point that is located opposite the receiver via a reflector that reflects the reference signal, and can be considered to have transmitted the reference signal to the receiver in the absence of the reflector. The multiple quasi-theoretical values are a sum of a path of a wireless signal between each of the multiple candidate points and the receiver, a path of a wireless signal between each of the multiple candidate points and the virtual reception point, or a path of a wireless signal between the receiver and the virtual transmission point.

An estimation system according to an aspect of the present disclosure includes a transmitter, an acquisition unit, an estimation unit, a first storage unit, and a second storage unit. The transmitter performs phase synthesis processing on a plurality of original signals to generate a plurality of radio signals, and transmits the plurality of radio signals from a plurality of antennas. The acquisition unit acquires a plurality of pieces of signal strength information of the plurality of radio signals received by a receiver present within a predetermined area. The estimation unit estimates the position of the receiver within the predetermined area. The first storage unit stores a plurality of pieces of position information. The plurality of pieces of position information indicate a plurality of positions at a plurality of candidate points for estimating the position of the receiver. The second storage unit stores a plurality of quasi-theoretical values. The plurality of quasi-theoretical values correspond one-to-one to each of the plurality of candidate points. The plurality of quasi-theoretical values are values related to a direct wave and a reflected wave received by the receiver when a radio signal is received at each of the plurality of candidate points. The estimation unit estimates the position of the receiver within the specified area based on the plurality of position information, the plurality of quasi-theoretical values, and the plurality of signal strength information acquired by the acquisition unit. A reference receiver that receives the plurality of wireless signals is disposed within the specified area, and a virtual point is set based on the position information indicating the position of the transmitter, the position information indicating the position of the reference receiver, and the signal strength when the reference receiver receives the plurality of wireless signals. The virtual point is a virtual reception point that is located opposite the transmitter via a reflector that reflects the plurality of wireless signals, and can be considered to have received the plurality of wireless signals in the absence of the reflector, or a virtual transmission point that is located opposite the reference receiver via a reflector that reflects the plurality of wireless signals, and can be considered to have transmitted the plurality of wireless signals to the reference receiver in the absence of the reflector. The plurality of quasi-theoretical values are a sum of a path of a wireless signal between each of the plurality of candidate points and the reference receiver, a path of a wireless signal between each of the plurality of candidate points and the virtual reception point, or a path of a wireless signal between the reference receiver and the virtual transmission point.

An estimation method according to one aspect of the present disclosure includes a receiving step, a generating step, and an estimating step. In the receiving step, a radio signal transmitted by a transmitter is received by a receiver. The receiver has a plurality of antennas. In the generating step, a phase synthesis process is performed on the radio signal received in the receiving step to generate a plurality of synthetic signals. In the estimating step, a position of the transmitter within a predetermined area is estimated. In the estimating step, a position of the transmitter within the predetermined area is estimated based on a plurality of pieces of position information, a plurality of quasi-theoretical values, and a plurality of signal strengths in the plurality of synthetic signals. The plurality of pieces of position information indicate positions of a plurality of candidate points for estimating the position of the transmitter within the predetermined area. The plurality of pieces of position information are information stored in advance. The plurality of quasi-theoretical values correspond one-to-one to each of the plurality of pieces of position information. The plurality of quasi-theoretical values are values related to a direct wave and a reflected wave received by the receiver when a radio signal is transmitted at each of the plurality of candidate points. The plurality of quasi-theoretical values are stored in advance. A reference transmitter that transmits a reference signal is disposed within the predetermined area, and a virtual point is set based on location information indicating the location of the receiver, location information indicating the location of the reference transmitter, and a signal strength when the reference signal is received by the receiver. The virtual point is a virtual reception point that is located opposite the reference transmitter via a reflector that reflects the reference signal, and can be considered to have received the reference signal in the absence of the reflector, or a virtual transmission point that is located opposite the receiver via a reflector that reflects the reference signal, and can be considered to have transmitted the reference signal to the receiver in the absence of the reflector. The multiple quasi-theoretical values are a sum of a path of a wireless signal between each of the multiple candidate points and the receiver, a path of a wireless signal between each of the multiple candidate points and the virtual reception point, or a path of a wireless signal between the receiver and the virtual transmission point .

The estimation method according to one aspect of the present disclosure includes a first receiving step, a setting step, a storage step, a second receiving step, and an estimation step. In the first receiving step, a direct wave and a reflected wave of a reference signal transmitted by a reference transmitter installed within a predetermined area are received by a receiver. The receiver has a plurality of antennas. In the setting step, a virtual reception point or a virtual transmission point is set based on position information of the receiver and the reference transmitter and the signal strength of the reference signal. The virtual reception point can be considered to have received the reflected wave. The virtual transmission point can be considered to have transmitted the reflected wave. In the storage step, a plurality of quasi-theoretical values are calculated in advance based on the position information of the receiver and the position information of the virtual reception point or the virtual transmission point, and stored in a storage unit. The plurality of quasi-theoretical values are values related to a direct wave and a reflected wave received by the receiver when a transmitter transmits a wireless signal at each of a plurality of candidate points within the predetermined area. In the second receiving step, a wireless signal transmitted by the transmitter is received by the receiver. In the estimation step, the position of the candidate point corresponding to the quasi-theoretical value among the multiple quasi-theoretical values that has the highest correlation with the signal strength of the radio signal received by the receiver in the second receiving step is estimated to be the position of the transmitter.

A program according to one aspect of the present disclosure is a program for causing one or more processors to execute the estimation method.

Fig. 1A is a schematic diagram showing an overview of an estimation system and a transmitter according to embodiment 1. Fig. 1B is an enlarged schematic diagram of the estimation system in Fig. 1A. FIG. 2 is a block diagram showing a functional configuration of the estimation system. FIG. 3 is a schematic diagram showing an outline of a virtual reception point in the estimation system. FIG. 4 is a schematic diagram showing an overview of a plurality of virtual reception points according to the estimation system. FIG. 5 is a schematic diagram showing an overview of a plurality of candidate points and a plurality of virtual reception points according to the estimation system. FIG. 6 is a schematic diagram showing an overview of a plurality of virtual reception points according to a modified estimation system. FIG. 7 is a schematic diagram showing an overview of a virtual transmission point according to a modified estimation system. Fig. 8A is a schematic diagram showing an overview of an estimation system and a receiver according to embodiment 2. Fig. 8B is an enlarged schematic diagram of the estimation system in Fig. 8A. FIG. 9 is a block diagram showing a functional configuration of the estimation system. FIG. 10 is a schematic diagram showing an outline of a virtual reception point in the estimation system.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. Note that elements common to the embodiments described below are designated by the same reference numerals, and redundant descriptions of the common elements will be omitted.

(Embodiment 1)
(1) Overview First, an overview of the estimation system 1 according to the present embodiment will be described with reference to FIG. 1A. The estimation system 1 is used in a positioning system (LPS: Local Positioning System) that measures the position of a transmitter 5 that transmits a radio signal using radio waves as a medium in a predetermined area A1 in a facility. The "facility" in the present disclosure is, for example, an office building, a factory, a commercial complex, an art museum, a museum, an amusement facility, a theme park, an airport, a train station, a dome stadium, a hotel, a house, etc., and includes a site and a building built on the site. In addition, the "facility" may be, for example, a moving body such as a ship or a railway vehicle. In addition, the "predetermined area" in the present disclosure is a room or the like in the facility, and is an area that includes a reflector that reflects the radio signal transmitted by the transmitter 5. In the present embodiment, a case in which the estimation system 1 is applied to a predetermined area A1 that is a room in a facility such as an office building will be described as an example. As shown in FIG. 1A, the predetermined area A1 in this embodiment is surrounded by walls 6 at four corners of the room. The walls 6 in this embodiment are reflectors that reflect the radio signal transmitted by the transmitter 5.

The transmitter 5 of this embodiment is configured, for example, as a beacon device that transmits a beacon signal (wireless signal) conforming to the BLE (Bluetooth (registered trademark) Low Energy) (hereinafter referred to as "BLE") standard. The transmitter 5 transmits a wireless signal from a transmission antenna. The wireless signal transmitted by the transmitter 5 of this embodiment includes information such as the identification information of the transmitter 5.

As shown in FIG. 1B, the estimation system 1 has multiple antennas 21 (three in the example of FIG. 1B) for receiving radio signals transmitted by the transmitter 5. The three antennas 21 in this embodiment are array antennas including antennas 21a, 21b, and 21c. In the following description, when describing a specific antenna 21 among the three antennas 21, antennas 21a, 21b, and 21c will be distinguished. In addition, when describing the three antennas 21 without distinguishing between them, they will simply be referred to as antennas 21.

The estimation system 1 of this embodiment is configured as a system capable of receiving wireless signals conforming to the BLE standard with three antennas 21. The estimation system 1 of this embodiment can estimate the position of the transmitter 5 that transmitted the wireless signal based on the signal strength (RSSI) of the wireless signal received by the three antennas 21.

(2) Details Hereinafter, details of the estimation system 1 according to this embodiment will be described with reference to FIGS. 1A to 5.

(2.1) Configuration of the Estimation System As shown in FIG. 2, the estimation system 1 of this embodiment includes a receiver 2, an estimation unit 3, and a storage unit 4.

The receiver 2 receives a radio signal emitted by the transmitter 5 (see Figure 1A). Upon receiving the radio signal, the receiver 2 generates multiple (four in the example of Figure 2) composite signals SS1 to SS4 based on the radio signal to estimate the position of the transmitter 5. The receiver 2 outputs the four generated composite signals SS1 to SS4 to the estimation unit 3. Details of the receiver 2 will be explained in the section "(2.3) Receiver configuration".

The estimation unit 3 estimates the position of the transmitter 5 (see FIG. 1A) based on the four signal strengths in the four composite signals SS1 to SS4 output from the receiver 2 and the position information 41 and quasi-theoretical value information 42 stored in the memory unit 4. Details of the estimation method by which the estimation unit 3 estimates the position of the transmitter 5 will be explained in the section "(3) Estimation method."

The storage unit 4 includes a non-transitory storage device such as a hard disk drive (HDD), a solid state drive (SSD), an optical disk drive, etc. The storage unit 4 stores position information 41 and quasi-theoretical value information 42.

The location information 41 includes information indicating the location of the receiver 2 (estimation system 1) within a predetermined area A1 (see FIG. 1A) and the reference transmitter 7 (see FIG. 3) described later. As shown in FIG. 1A, the location information 41 in this embodiment is coordinate information in a three-dimensional coordinate system. For example, the estimation system 1 in this embodiment is located at coordinates (1, 1, 1).

The quasi-theoretical value information 42 is information on multiple quasi-theoretical values that correspond one-to-one to position information indicating the positions of multiple (36 in the example of FIG. 1A) candidate points P0 for estimating the position of the transmitter 5 within the specified area A1 (see Table 1). In this embodiment, the position information of the multiple candidate points P0 is coordinate information in a three-dimensional coordinate system. For example, the coordinates of candidate point P11 are (1, 1, 1), and the coordinates of candidate point P66 are (6, 6, 1). The quasi-theoretical values are steering vectors for determining the degree of correlation between the signal strength of the wireless signal received by the estimation system 1 and the multiple candidate points P0.

(2.2) Quasi-Theoretical Value Next, the quasi-theoretical value will be described in detail with reference to FIGS.

In this embodiment, the quasi-theoretical value is calculated in advance using a reference transmitter 7 (reference beacon) placed in the specified area A1. The reference transmitter 7 is composed of, for example, a beacon device that transmits a beacon signal (radio signal) conforming to the BLE standard from a transmission antenna. In the following description, the radio signal transmitted by the reference transmitter 7 is referred to as the "reference signal." The reference signal transmitted by the reference transmitter 7 in this embodiment includes information such as the identification information of the reference transmitter 7.

As shown in FIG. 3, when the reference transmitter 7 arranged at coordinates (X1, Y1, Z1) in a predetermined area A1 including a wall 6, which is a reflector, transmits a reference signal, a part of the transmitted reference signal reaches the receiver 2 directly, and a part of the transmitted reference signal reaches the receiver 2 after being reflected by the wall 6. In the example of FIG. 3, a part of the radio signal transmitted by the reference transmitter 7 is reflected by a reflection point 8 of the wall 62 and reaches the receiver 2. Therefore, the signal strength of the reference signal observed by the receiver 2 is the sum of the direct wave and the reflected wave. Here, the "direct wave" refers to a radio signal (reference signal) transmitted by the transmitter 5 or the reference transmitter 7 that is received by the receiver 2 directly (i.e., without being reflected by a reflector such as the wall 6) from the source of the radio signal, such as the transmitter 5 or the reference transmitter 7. Also, the "reflected wave" refers to a radio signal (reference signal) transmitted by the transmitter 5 or the reference transmitter 7 that is reflected by a reflector such as the wall 6 and then received by the receiver 2. In the example of Fig. 3, of the reference signals transmitted by the reference transmitter 7, the direct wave is the reference signal received by the receiver 2 through the path a1, and the reflected wave is the reference signal received by the receiver 2 through the paths a21 and a23. Note that the "path" in this disclosure refers to the path of the wireless signal (reference signal). Also, a path between a certain point (first point) and another point (second point) may be expressed by a vector from the first point to the second point, or a vector from the second point to the first point.

The estimation system 1 can estimate the direction of arrival θ1 (see FIG. 1B) of the radio signal based on the signal strength of the received radio signal (reference signal), and can therefore estimate the path a0 of the radio signal obtained by adding together the direct wave and the reflected wave. In the present embodiment, the position information 41 contains information indicating the position (coordinates) of the receiver 2 and information indicating the position of the reference transmitter 7. Therefore, the estimation system 1 can calculate the path a1 of the direct wave in the reference signal transmitted from the reference transmitter 7 based on the position information of the receiver 2 and the reference transmitter 7. The estimation system 1 can then calculate the path a2 of the reflected wave based on the path a0 of the reference signal obtained by adding together the direct wave and the reflected wave, and the path a1 of the direct wave. In other words, the estimation system 1 estimates the path a2 of the reflected wave that has the highest correlation between the signal strength of the received reference signal and the path a0 obtained by adding together the path a1 of the direct wave and the path a2 of the reflected wave. In this embodiment, the path a2 of the reflected wave is a path between the virtual reception point V1, which can be considered to have received the reference signal if there is no wall 62 (reflector), and the reference transmitter 7. The virtual reception point V1 is located opposite the reference transmitter 7 via the reflection point 8 of the wall 62 that reflects the reference signal, and the length of the path a23 of the reference signal between the reflection point 8 and the receiver 2 is equal to the length of the path a22 of the reference signal between the reflection point 8 and the virtual reception point V1. The reference transmitter 7, the reflection point 8 of the wall 62 that reflects the reference signal, and the virtual reception point V1 are aligned on a straight line. The coordinates (X2, Y2, Z2) of the virtual reception point V1 are set based on the position information indicating the position of the receiver 2, the position information indicating the position of the reference transmitter 7, and the signal strength when the receiver 2 receives the reference signal transmitted by the reference transmitter 7.

The quasi-theoretical value is the sum of the path a1 of the radio signal between the candidate point P0 and the receiver 2, and the path a2 of the radio signal between the candidate point P0 and the virtual reception point V1 corresponding to the candidate point P0. The quasi-theoretical value information 42 is information that associates such a quasi-theoretical value with each candidate point P0. That is, for each of the multiple candidate points P0 in this embodiment, a virtual reception point V1 corresponding to each of the multiple candidate points P0 is set.

In this embodiment, as shown in FIG. 4, four reference transmitters 7a-7d are installed in the specified area A1, and four virtual reception points V2-V5 corresponding to each of the multiple candidate points P0 are set. In the following description, when there is no particular distinction between the four reference transmitters 7a-7d, they are simply referred to as "reference transmitter 7." As shown in FIG. 4, it is preferable to install the same number of reference transmitters 7 as the number of reflectors (walls 61-64) in the specified area A1. As shown in FIG. 4, the specified area A1 is divided into four areas A11-A14 by two intersecting dashed lines (two diagonal lines in the specified area A1).

The area A11 is an area where many radio signals are reflected by the wall 61 when the transmitter 5 transmits radio signals at multiple candidate points P0 present in the area A11. The reference transmitter 7a is installed in the area A11, and information indicating the position of the reference transmitter 7a is included in the position information 41. The position of the virtual reception point V2 is set based on the position information indicating the position of the receiver 2, the position information indicating the position of the reference transmitter 7a, and the signal strength when the receiver 2 receives the reference signal transmitted by the reference transmitter 7a. The virtual reception point V2 is a virtual point that can be considered to have received the reference signal transmitted by the reference transmitter 7a if there was no wall 61 (reflector). Between the virtual reception point V2 and the reference transmitter 7a is a reflection point 8a of the wall 61. The virtual reception point V2 is a virtual reception point corresponding to the area A11. Each of the multiple candidate points P0 in the region 11 is associated with a quasi-theoretical value obtained by adding up the path a1 of the wireless signal between the candidate point P0 and the receiver 2 and the path a2 of the wireless signal between the candidate point P0 and the virtual reception point V2. As shown in Fig. 5, for example, the candidate point P36 is associated with a quasi-theoretical value obtained by adding up the path a1 of the wireless signal between the candidate point P36 and the receiver 2 (estimation system 1) and the path a2 of the wireless signal between the candidate point P36 and the virtual reception point V2.

As shown in FIG. 4, when the transmitter 5 transmits a radio signal at a plurality of candidate points P0 present in the area A12, the area A12 is an area where many radio signals are reflected by the wall 62. The reference transmitter 7b is installed in the area A12, and information indicating the position of the reference transmitter 7b is included in the position information 41. The position of the virtual reception point V3 is set based on the position information indicating the position of the receiver 2, the position information indicating the position of the reference transmitter 7b, and the signal strength when the receiver 2 receives the reference signal transmitted by the reference transmitter 7b. The virtual reception point V3 is a virtual point that can be considered to have been able to receive the reference signal transmitted by the reference transmitter 7b if there was no wall 62 (reflector). Between the virtual reception point V3 and the reference transmitter 7b is a reflection point 8b of the wall 62. The virtual reception point V3 is a virtual reception point corresponding to the area A12. Each of the multiple candidate points P0 in the region 12 is associated with a quasi-theoretical value obtained by adding up the path a1 of the wireless signal between the candidate point P0 and the receiver 2 and the path a2 of the wireless signal between the candidate point P0 and the virtual reception point V3. As shown in Fig. 5, for example, the candidate point P63 is associated with a quasi-theoretical value obtained by adding up the path a1 of the wireless signal between the candidate point P63 and the receiver 2 and the path a2 of the wireless signal between the candidate point P63 and the virtual reception point V3.

As shown in FIG. 4, when the transmitter 5 transmits a radio signal at a plurality of candidate points P0 present in the area A13, the area A13 is an area where many radio signals are reflected by the wall 63. The reference transmitter 7c is installed in the area A13, and information indicating the position of the reference transmitter 7c is included in the position information 41. The position of the virtual reception point V4 is set based on the position information indicating the position of the receiver 2, the position information indicating the position of the reference transmitter 7c, and the signal strength when the receiver 2 receives the reference signal transmitted by the reference transmitter 7c. The virtual reception point V4 is a virtual point that can be considered to have received the reference signal transmitted by the reference transmitter 7c if there was no wall 63 (reflector). Between the virtual reception point V4 and the reference transmitter 7c is a reflection point 8c of the wall 63. The virtual reception point V4 is a virtual reception point corresponding to the area A13. Each of the multiple candidate points P0 in the region 13 is associated with a quasi-theoretical value obtained by adding up the path a1 of the wireless signal between the candidate point P0 and the receiver 2 and the path a2 of the wireless signal between the candidate point P0 and the virtual reception point V4. As shown in Fig. 5, for example, the candidate point P51 is associated with a quasi-theoretical value obtained by adding up the path a1 of the wireless signal between the candidate point P51 and the receiver 2 and the path a2 of the wireless signal between the candidate point P51 and the virtual reception point V4.

As shown in FIG. 4, when the transmitter 5 transmits a radio signal at a plurality of candidate points P0 present in the area A14, the area A14 is an area where many radio signals are reflected by the wall 64. The reference transmitter 7d is installed in the area A14, and information indicating the position of the reference transmitter 7d is included in the position information 41. The position of the virtual reception point V5 is set based on the position information indicating the position of the receiver 2, the position information indicating the position of the reference transmitter 7d, and the signal strength when the receiver 2 receives the reference signal transmitted by the reference transmitter 7d. The virtual reception point V5 is a virtual point that can be considered to have been able to receive the reference signal transmitted by the reference transmitter 7d if there was no wall 64 (reflector). Between the virtual reception point V5 and the reference transmitter 7d is a reflection point 8d of the wall 64. The virtual reception point V5 is a virtual reception point corresponding to the area A14. Each of the multiple candidate points P0 in the region 14 is associated with a quasi-theoretical value obtained by adding up the path a1 of the radio signal between the candidate point P0 and the receiver 2 and the path a2 of the radio signal between the candidate point P0 and the virtual reception point V5. As shown in Fig. 5, for example, the candidate point P13 is associated with a quasi-theoretical value obtained by adding up the path a1 of the radio signal between the candidate point P13 and the receiver 2 and the path a2 of the radio signal between the candidate point P13 and the virtual reception point V5. The quasi-theoretical value is a value that takes into account not only the direct wave received by the receiver 2 but also the reflected wave received by the receiver 2, and therefore is a value that allows the estimation unit 3 to estimate the position (coordinates) of the transmitter 5 rather than the position direction of the transmitter 5.

As described later, the estimation system 1 of this embodiment uses such a quasi-theoretical value as a steering vector to estimate the position of the transmitter 5 within the specified area A1.

(2.3) Configuration of the Receiver Next, details of the receiver 2 will be described with reference to FIGS. 1A to 2.

As shown in Figure 2, the receiver 2 has three antennas 21, a phase synthesis unit 22, and an output unit 24.

The three antennas 21 receive a radio signal transmitted by the transmitter 5 (see FIG. 1A). When the three antennas 21 receive the radio signal, they output multiple input signals IS1 to IS3 (three in the example of FIG. 2) based on the radio signal to the phase synthesizer 22. Specifically, antenna 21a outputs input signal IS1 to phase synthesizer 23a, antenna 21b outputs input signal IS2 to phase synthesizer 23b, and antenna 21c outputs input signal IS3 to phase synthesizer 23c.

The phase synthesis unit 22 performs synthesis processing on the three input signals IS1 to IS3 input from the three antennas 21, and generates multiple (four in the example of Figure 2) synthesis signals SS1 to SS4 for estimating the position of the transmitter 5.

The phase synthesizer 22 includes a phase synthesizer 23a, a phase synthesizer 23b, a phase synthesizer 23c, a phase synthesizer 23d, and a phase synthesizer 23e. In the following description, when the phase synthesizers 23a, 23b, 23c, 23d, and 23e are not distinguished from each other, they are simply referred to as a phase synthesizer 23. The phase synthesizer 23 is, for example, a 90-degree hybrid unit (hybrid element). The phase synthesizer 23 of this embodiment outputs a signal having a power value of 1/√2 times from the first output terminal O1 and the second output terminal O2 compared to the three input signals IS1 to IS3 input to the first input terminal I1 and the second input terminal I2. In addition, the phase synthesizer 23 outputs a signal having the same phase as the three input signals IS1 to IS3 input to the first input terminal I1 from the first output terminal O1, and outputs a signal having a phase delay of 90 degrees from the second output terminal O2.

The phase synthesizer 23a outputs a signal IS4 from the first output terminal O1, which has a power value of 1/√2 times that of the input signal IS1 input to the first input terminal I1 and is in phase with the input signal IS4.

The phase synthesizer 23b outputs a signal IS5, which has a power value of 1/√2 times and a phase delay of 90 degrees compared to the input signal IS2 input to the first input terminal I1, from the second output terminal O2. The phase synthesizer 23b also outputs a signal IS6, which has a power value of 1/√2 times and is in phase with the input signal IS2, from the first output terminal O1.

The phase synthesizer 23c outputs a signal IS7 from the second output terminal O2, which has a power value of 1/√2 times that of the input signal IS3 input to the second input terminal I2 and is in phase with the input signal IS7.

The phase synthesizer 23d receives the signal IS4 at the second input terminal I2 and receives the signal IS5 at the first input terminal I1. The phase synthesizer 23d outputs a composite signal SS1 from the first output terminal O1, which is obtained by adding together a signal whose power value is 1/√2 times the power of the signal IS4 and whose phase is delayed by 90 degrees, and a signal whose power value is 1/√2 times the power of the signal IS5 and whose phase is the same. The phase synthesizer 23d also outputs a composite signal SS2 from the second output terminal O2, which is obtained by adding together a signal whose power value is 1/√2 times the power of the signal IS4 and whose phase is delayed by 90 degrees, and a signal whose power value is 1/√2 times the power of the signal IS5 and whose phase is delayed by 90 degrees.

The phase synthesizer 23e receives the signal IS6 at the second input terminal I2 and receives the signal IS7 at the first input terminal I1. The phase synthesizer 23e outputs a composite signal SS3 from the first output terminal O1, which is obtained by adding together a signal whose power value is 1/√2 times the power of the signal IS6 and whose phase is delayed by 90 degrees, and a signal whose power value is 1/√2 times the power of the signal IS7 and whose phase is the same. The phase synthesizer 23e also outputs a composite signal SS4 from the second output terminal O2, which is obtained by adding together a signal whose power value is 1/√2 times the power of the signal IS6 and whose phase is delayed by 90 degrees, and a signal whose power value is 1/√2 times the power of the signal IS7 and whose phase is delayed by 90 degrees.

The output unit 24 outputs the four synthesized signals SS1 to SS4 generated by the phase synthesis unit 22 to the estimation unit 3.

(3) Estimation Method Next, an estimation method by which the estimation unit 3 estimates the position of the transmitter 5 within the predetermined area A1 will be described with reference to FIGS. 1A to 2. FIG.

As shown in Fig. 1B, the complex propagation channel between antenna 21a and the transmitting antenna of transmitter 5 is h1, the complex propagation channel between antenna 21b and the transmitting antenna is h2, and the complex propagation channel between antenna 21c and the transmitting antenna is h3. The distance between antenna 21a and antenna 21b, and the distance between antenna 21b and antenna 21c are d1. It is also assumed that transmitter 5 is located at an angle θ1 based on the broadside direction (X direction) of the array antenna composed of antennas 21a, 21b, and 21c.

The propagation channels can be collectively expressed as equation (1).

The correlation matrix of this transmission channel can be expressed as equation (2).

Here, the symbol H represents complex conjugate transpose, and the symbol * represents complex conjugate. Usually, the diagonal terms of the correlation matrix R are real numbers, and the off-diagonal terms are complex numbers. By calculating the correlation matrix R, the estimation unit 3 can estimate the direction of arrival of the wireless signal. The estimation unit 3 calculates the correlation matrix R based on information related to the signal strength. Using the propagation channel of equation (1), the amplitudes of the four composite signals SS1 to SS4 input to the estimation unit 3 can be expressed as equations (3) to (6).

|y1| represents the amplitude of the combined signal SS1 output from the first output terminal O1 of the phase combiner 23d. |y2| represents the amplitude of the combined signal SS2 output from the second output terminal O2 of the phase combiner 23d. |y3| represents the amplitude of the combined signal SS3 output from the first output terminal O1 of the phase combiner 23e. |y4| represents the amplitude of the combined signal SS4 output from the second output terminal O2 of the phase combiner 23e. Furthermore, from the signal strength, the gain of the channel on the left side of equations (3) to (6) can be expressed as equations (7) to (10).

Focusing on the gain difference obtained through phase synthesizer 23d, equation (11) is obtained.

Furthermore, from the relationship in equation (11), equation (12) is obtained, and the real parts of R12 and R21 can be found. Here, α represents the argument of R12.

Furthermore, if we look at the sum of the gains obtained through the phase synthesizer 23d, equation (13) is obtained from the arithmetic mean relationship.

Here, it is assumed that the propagation loss from the transmitting antenna of the transmitter 5 to the antenna 21a is equal to the propagation loss from the transmitting antenna to the antenna 21b, and that |h1| and |h2| are approximately equal. When |h1| and |h2| are approximately equal, α, which is the argument of R12, can be expressed by equation (14).

Furthermore, when |h1| and |h2| are approximately equal, equation (15) is obtained.

Here, A is a real constant. Of the correlation matrix R shown in equation (2), the correlation matrix for the composite signals SS1 and SS2 output from the phase combiner 23d is defined as R1. When the correlation matrix R1 is expressed using A and α, equation (16) is obtained.

Next, by focusing on the difference in gain obtained through the phase combiner 23e, we obtain equation (17), which allows us to calculate the imaginary parts of R23 and R32. Here, β represents the argument of R23.

Moreover, when the sum of the gains obtained through the phase combiner 23e is taken into account, the arithmetic mean relationship gives us the following equation (18). Here, it is assumed that the propagation loss from the transmitting antenna of the transmitter 5 to the antenna 21b is equal to the propagation loss from the transmitting antenna to the antenna 21c, and that |h2| and |h3| are approximately equal.

When |h2| and |h3| are approximately equal, β, the argument of R23, can be expressed by equation (19).

Similarly, when |h2| and |h3| are approximately equal, equation (20) is obtained. Here, B is a real constant. Of the correlation matrix R, the correlation matrix for the composite signals SS3 and SS4 output from the phase combiner 23e is defined as R2.

When the correlation matrix R2 is expressed using B and β, equation (21) is obtained and the correlation matrix R is estimated.

R13 represents the correlation of the radio signals between antennas 21a and 21c. R13 can be expressed by equation (22) using the calculated |R23|.

From the above, the estimated correlation matrix R can be expressed by equation (23).

The estimation unit 3 can estimate the direction of the transmitter 5 by applying various direction-of-arrival estimation algorithms to the correlation matrix R. Specifically, when the beamformer method is used, the estimation unit 3 can estimate the direction of the transmitter 5 by taking the correlation between the correlation matrix R and the steering vector (theoretical value) from the product of the correlation matrix R and the steering vector expressed by equation (24).

Here, d is the antenna spacing, k is the wave number, and k = 2π/λ. Note that λ is the wavelength. Using this steering vector and the correlation matrix R, the evaluation function P(θ) can be expressed by equation (25).

The estimation unit 3 substitutes various values for θ in equation (25) and determines that the direction in which the evaluation function P(θ) is maximum is the departure direction of the wireless signal.

In addition, the estimation unit 3 of this embodiment estimates the position of the transmitter 5 by using the quasi-theoretical value (see Table 1) included in the quasi-theoretical value information 42 instead of the theoretical value expressed by equation (24). Note that, although an example of direction estimation using the beamformer method is shown here, the direction of the transmitter 5 may be calculated using the MUSIC method. Alternatively, the direction of the transmitter 5 may be calculated using the CAPON method. Alternatively, the direction of the transmitter 5 may be calculated using the compressed sensing method.

The estimation unit 3 estimates the position of the transmitter 5 using one of the above-mentioned direction-of-arrival estimation algorithms from the quasi-theoretical values corresponding to the correlation matrix R and the steering vector. The estimation unit 3 selects a quasi-theoretical value that maximizes the evaluation function (degree of correlation) from the multiple quasi-theoretical values and correlation matrix R included in the quasi-theoretical value information 42. The estimation unit 3 then refers to the position information of the candidate point P0 corresponding to the selected quasi-theoretical value, and estimates the position of the candidate point P0 within the specified area A1 as the position of the transmitter 5.

(4) Effects As described above, the estimation system 1 according to this embodiment includes a receiver 2, an estimation unit 3, and a storage unit 4 (first storage unit, second storage unit). The storage unit 4 stores position information 41 and quasi-theoretical value information 42 in advance. The receiver 2 includes three antennas 21 for receiving radio signals, and a phase synthesis unit 22 for performing phase synthesis processing on the radio signals received by the three antennas 21 to generate four synthetic signals SS1 to SS4. The estimation unit 3 estimates the position of the transmitter 5 within the predetermined area A1 based on the four signal strengths of the four synthetic signals SS1 to SS4, the position information of the multiple candidate points P0, and the multiple quasi-theoretical values that correspond one-to-one to the position information of the multiple candidate points. Since the multiple quasi-theoretical values that take into account the reflected wave components of the radio signal correspond one-to-one to the position information of the multiple candidate points, the position of the transmitter 5 can be estimated. As a result, for example, the position of the transmitter 5 can be estimated with one receiver 2, and the number of multiple antennas 21 that the estimation system 1 has can be reduced.

In addition, in this embodiment, the position information of the multiple candidate points P0, the position information of the receiver 2, and the position information of the reference transmitter 7 (7a to 7d) are position information indicating a three-dimensional position. Therefore, the estimation unit 3 in this embodiment can estimate the three-dimensional position of the transmitter 5 within the specified area A1.

Furthermore, the estimation unit 3 of this embodiment selects, from among the multiple candidate points P0, a quasi-theoretical value that has the highest correlation with the correlation matrix R regarding the signal strengths of the four composite signals SS1 to SS4, and estimates the position (coordinates) of the candidate point P0 that corresponds to the quasi-theoretical value as the position of the transmitter 5. This makes it possible to improve the accuracy of the estimation of the position of the transmitter 5 by the estimation unit 3.

In addition, the multiple quasi-theoretical values of this embodiment are the sum of the path a1 of the radio signal (direct wave) between each of the multiple candidate points P0 and the receiver 2, and one or more paths a2 of the radio signal (reflected wave) between each of the multiple candidate points P0 and each of the four virtual reception points V2 to V5. The positions of the four virtual reception points V2 to V5 are set based on position information indicating the position of the receiver 2, position information indicating the positions of the four reference transmitters 7a to 7d, and the signal strength when the receiver 2 receives the reference signal transmitted by the four reference transmitters 7a to 7d. Since the multiple quasi-theoretical values are the sum of the path a1 of the direct wave and the path a2 of the reflected wave, the estimation unit 3 can estimate the position of the transmitter 5 from the radio signal received by one receiver 2, for example.

The virtual point in this embodiment is located opposite the reference transmitter 7 via a wall 6 (reflection point 8) that reflects the reference signal, and is a virtual point that can be considered to have received a reflected wave of the reference signal if the wall 6 is not present. In addition, the length of the path a22 of the wireless signal between the virtual reception point V1 and the reflection point 8 is equal to the length of the path a23 of the wireless signal between the receiver 2 and the reflection point 8. By setting such a virtual reception point V1 and then determining the quasi-theoretical value, the quasi-theoretical value becomes a value that takes into account the path a2 of the reflected wave.

(5) Modifications Functions similar to those of the estimation system 1 may be embodied in an estimation method, a program, or a recording medium having a program recorded thereon.

The estimation method according to the first embodiment includes a receiving step, a generating step, and an estimating step. In the receiving step, a radio signal transmitted by the transmitter 5 is received by the multiple antennas 21. In the generating step, a phase synthesis process is performed on the radio signal received in the receiving step to generate multiple synthetic signals SS1 to SS4. In the estimating step, the position of the transmitter 5 within the predetermined area A1 is estimated. In the estimating step, the position of the transmitter 5 within the predetermined area A1 is estimated based on multiple pieces of position information, multiple quasi-theoretical values, and multiple signal strengths in the multiple synthetic signals SS1 to SS4. The multiple pieces of position information indicate the positions of multiple candidate points P0 for estimating the position of the transmitter 5 within the predetermined area A1. The multiple pieces of position information are information stored in advance. The multiple quasi-theoretical values correspond one-to-one to each of the multiple pieces of position information. The multiple quasi-theoretical values are values related to the direct waves and reflected waves received by the multiple antennas 21 when a radio signal is transmitted at each of the multiple candidate points P0. The multiple quasi-theoretical values are stored in advance.

The estimation method according to the first embodiment includes a first receiving step, a setting step, a storage step, a second receiving step, and an estimation step. In the first receiving step, the receiver 2 receives direct waves and reflected waves of a reference signal transmitted by a reference transmitter 7 installed in a predetermined area A1. The receiver 2 has a plurality of antennas 21. In the setting step, a virtual reception point V1 or a virtual transmission point V8 is set based on the position information of the receiver 2 and the reference transmitter 7 and the signal strength of the reference signal. The virtual reception point V1 can be regarded as having received a reflected wave. The virtual transmission point V8 can be regarded as having transmitted a reflected wave. In the storage step, a plurality of quasi-theoretical values are stored in the storage unit 4 based on the position information of the receiver 2 and the position information of the virtual reception point V1 or the virtual transmission point V8. The plurality of quasi-theoretical values are values related to the direct waves and reflected waves received by the receiver 2 when the transmitter 5 transmits a wireless signal at each of a plurality of candidate points P0 in the predetermined area A1. In the second receiving step, the radio signal transmitted by the transmitter 5 is received by the receiver 2. In the estimating step, the position of the candidate point P0 corresponding to the quasi-theoretical value having the highest correlation with the signal strength of the radio signal received by the receiver 2 in the second receiving step among the multiple quasi-theoretical values is estimated as the position of the transmitter 5.

In addition, the (computer) program of embodiment 1 is a program for causing one or more processors to execute the above-mentioned receiving step, generating step, and estimating step.

In addition, the (computer) program of embodiment 1 is a program for causing one or more processors to execute the above-mentioned first receiving step, setting step, storage step, second receiving step, and estimation step.

The execution subject of the estimation system 1 and the estimation method includes a computer system. The computer system is mainly composed of a processor and a memory as hardware. The processor executes a program recorded in the memory of the computer system to realize the function of the execution subject of the estimation system 1 and the estimation method. The program may be pre-recorded in the memory of the computer system. The program may be provided through an electric communication line, or may be provided by recording it on a recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The multiple electronic circuits may be integrated in one chip or distributed across multiple chips. The multiple chips may be integrated in one device or distributed across multiple devices.

In addition, in this embodiment, the estimation system 1 is realized in one system including the receiver 2 and the estimation unit 3, but it may be realized in two or more systems. For example, the functions of the receiver 2 and the estimation unit 3 may be distributed across two or more systems. At least one function of the receiver 2 and the estimation unit 3 may be distributed across two or more systems. The functions of the receiver 2 and the estimation unit 3 may be distributed across multiple devices. For example, the functions of the receiver 2 (e.g., the three antennas 21 and the phase synthesis unit 22) may be distributed across two or more devices. At least some of the functions of the estimation system 1 may be realized, for example, by cloud computing.

The transmitter 5 is not limited to a beacon device that transmits a beacon signal conforming to the BLE standard. The transmitter 5 may be, for example, a device that transmits a wireless signal conforming to the Wi-Fi (registered trademark) standard. Similarly, the estimation system 1 is not limited to a system capable of receiving a wireless signal conforming to the BLE standard. The estimation system 1 may be, for example, a system capable of receiving a wireless signal conforming to the Wi-Fi standard.

It is not essential that the position information 41 of the memory unit 4 includes the position information of the reference transmitter 7 (reference transmitters 7a to 7d). For example, the reference transmitter 7 may transmit a wireless signal including its own position information, and the receiver 2 may obtain the position information of the reference transmitter 7 from the wireless signal.

In this embodiment, the estimation system 1 includes a memory unit 4, but the estimation system 1 may include a first memory unit and a second memory unit instead of the memory unit 4. In this case, the first memory unit stores position information 41, and the second memory unit stores quasi-theoretical value information 42.

5, a quasi-theoretical value may be set for a candidate point located on the boundary between two areas A11 and A12, such as candidate point P44, taking into account the reflected wave reflected by the wall 61 of area A11 and the reflected wave reflected by the wall 62 of area A12. For example, candidate point P44 is associated with a quasi-theoretical value obtained by adding up the path of the wireless signal between candidate point P44 and receiver 2, the path of the wireless signal between candidate point P44 and virtual reception point V2, and the path of the wireless signal between candidate point P44 and virtual reception point V3. Also, a quasi-theoretical value may be set for each of the multiple candidate points P0, taking into account the reflected wave reflected by each of the four walls 61 to 64. In this case, for example, the quasi-theoretical value is obtained by adding up the path of the wireless signal between candidate point P0 and receiver 2 and all four paths of the wireless signal between candidate point P0 and the four virtual reception points V2 to V5. The four virtual reception points V2 to V5 are set based on the position information of the receiver 2, the four position information of the four reference transmitters 7a to 7d (see FIG. 4), and the four reference signals transmitted by the four reference transmitters 7a to 7d. In addition, there are four walls 61 to 64 (four reflection points 8a to 8d) that reflect the reference signals between the four virtual reception points V2 to V5 and the multiple candidate points P0. In this way, a quasi-theoretical value that takes into account multiple reflected waves is associated with each candidate point P0, thereby improving the accuracy with which the estimation system 1 estimates the position of the transmitter 5.

As shown in Fig. 6, multiple (two in the example of Fig. 6) virtual reception points V6, V7 may be set based on the position information of one reference transmitter 7, the position information of the receiver 2, and the signal strength when the receiver 2 receives a reference signal transmitted by one reference transmitter 7. In this case, the quasi-theoretical value is the sum of multiple paths a1 between each of the multiple candidate points P0 and the receiver 2, and two paths a2 of the radio signal between each of the multiple candidate points P0 and the two virtual reception points V6, V7. In this way, the accuracy of the estimation system 1 estimating the position of the transmitter 5 is improved by associating each candidate point P0 with a quasi-theoretical value that takes into account multiple reflected waves.

When estimating the position of the transmitter 5 using virtual reception points, the estimation unit 3 takes into account reflected waves from walls 6, etc., and improves the accuracy of direction estimation by using the sum of multiple steering vectors for equation (24). If the directions of radio waves arriving at L virtual reception points from the transmitting antenna are θ1 to θL (L is the number of arriving waves), the ideal signal vector obtained by adding up multiple steering vectors can be expressed by equation (26).

Here, Al is the amplitude correction coefficient for the arriving wave, and is a complex value that takes into account attenuation and phase rotation due to reflection at the wall 6 through which the arriving wave passes. By using a' instead of a(θ) in equation (25), the estimation unit 3 can improve the positioning accuracy by taking multiple reflections into account. θ1 to θL are the directions of the radio waves arriving at each virtual reception point. When the reference signal transmitted from the reference transmitter 7 (transmission point) is received (observed) by the receiver 2 (reception point), the estimation unit 3 determines L virtual reception points so that the received radio signal (observation signal) and the predicted signal calculated using equation (26) match best.

As shown in FIG. 7, the quasi-theoretical value may be a value obtained by setting a virtual transmission point V8 instead of a virtual reception point. The virtual transmission point V8 is located at a position facing the reference transmitter 7 through a wall 6 that reflects the reference signal (at a position facing the receiver 2 through a reflection point 8), and is a virtual point that can be considered to have transmitted a reflected wave of the reference signal if the wall 6 is not present. Note that the virtual transmission point V8, the reflection point 8 of the wall 6 that reflects the reference signal, and the receiver 2 are aligned in a straight line. In addition, the length of the path a24 of the radio signal between the virtual transmission point V8 and the reflection point 8 is equal to the length of the path a21 of the radio signal between the reference transmitter 7 and the reflection point 8. By setting such a virtual transmission point V8 and then setting the quasi-theoretical value, the quasi-theoretical value becomes a value that takes into account the path a2 of the reflected wave. The multiple quasi-theoretical values when the virtual transmission point V8 is set are the sum of the path a1 of the wireless signal (direct wave) between each of the multiple candidate points P0 and the receiver 2, and the path a2 of the wireless signal (reflected wave) between the receiver 2 and the virtual transmission point V8. The position of the virtual transmission point V8 is set based on position information indicating the position of the receiver 2, position information indicating the position of the reference transmitter 7, and the signal strength when the receiver 2 receives the reference signal transmitted by the reference transmitter 7. Since the multiple quasi-theoretical values are the sum of the path a1 of the direct wave and the path a2 of the reflected wave, the estimation unit 3 can estimate the position of the transmitter 5 from the wireless signal received by one receiver 2, for example.

The virtual transmission point V8 may be a plurality of virtual transmission points V8 set for one reference transmitter 7. Also, the virtual transmission point V8 may be four virtual transmission points V8 set for each of the four reference transmitters 7a to 7d.

In the first embodiment, the case where the same number of reference transmitters 7 are installed in the predetermined area A1 as the number of reflectors (walls 61-64) is exemplified, but the number of reference transmitters 7 installed in the predetermined area A1 is not limited to the same number as the number of reflectors. In other words, the number of reference transmitters 7 installed in the predetermined area A1 may be greater than the number of reflectors. Multiple reference transmitters 7 may be installed evenly within the predetermined area A1, and for example, a reference transmitter 7 may be installed at all positions of multiple candidate points P0.

In the case where multiple reference transmitters 7 are evenly installed within a predetermined area A1 and multiple virtual reception points V1 are set using multiple reference transmitters 7, the quasi-theoretical value corresponding to each of the multiple candidate points P0 uses the path a2 between each candidate point P0 and the virtual reception point V1 set using a reference transmitter 7 that is close to each candidate point P0. In other words, the quasi-theoretical value corresponding to each of the multiple candidate points P0 is unrelated to the virtual reception point V1 set using a reference transmitter 7 that is not close to each candidate point P0 (located far from each candidate point P0).

A single virtual point (virtual reception point V1 or virtual transmission point V8) may also be set using multiple reference transmitters 7. For example, if a reference transmitter 7 is installed at all of the positions of multiple candidate points P0, multiple virtual points that can be observed using multiple reference transmitters 7 that are close to each other are considered to be close to each other. When setting a virtual point using a reference transmitter 7, there may be cases where the virtual point cannot be set due to the generation of a virtual image, but the correct virtual point can be set by selecting a common virtual point using multiple reference transmitters 7 that are close to each other.

In addition, when setting a virtual point using the reference transmitter 7, the position of the virtual point may be estimated for each of the three frequencies of the Bluetooth advertising channels 37ch, 38ch, and 39ch, and the virtual point whose position is commonly estimated for the three frequencies may be set as the virtual point.

(Embodiment 2)
(1) Overview An overview of the estimation system 1a of the second embodiment will be described with reference to Figures 8A and 8B. The transmitter 5a included in the estimation system 1a of this embodiment has multiple (three in the illustrated example) antennas 51 for transmitting multiple wireless signals. The multiple antennas 51 of this embodiment are array antennas including antennas 51a, 51b, and 51c. In the following description, when describing a specific antenna 51 among the multiple antennas 51, the antennas 51a, 51b, and 51c will be distinguished from one another. In addition, when describing the multiple antennas 51 without distinguishing between them, they will simply be referred to as antennas 51.

The receiver 2a of this embodiment is equipped with a receiving antenna that receives multiple wireless signals transmitted from multiple antennas 51. For example, the receiver 2a of this embodiment is a smartphone or the like carried by a user within the specified area A1.

The estimation system 1a of this embodiment can estimate the position of the receiver 2a that received multiple radio signals based on the signal strength of the multiple radio signals received by the receiving antenna of the receiver 2a.

(2) Details Hereinafter, details of the estimation system 1a according to this embodiment will be described with reference to FIGS. 8A to 10.

(2.1) Configuration of the Estimation System As shown in FIG. 9, an estimation system 1a of this embodiment includes a transmitter 5a, an acquisition unit 10, an estimation unit 3a, and a storage unit 4a.

The transmitter 5a is composed of a beacon device that transmits a beacon signal (radio signal) conforming to the BLE standard, for example. The radio signal transmitted by the transmitter 5a in this embodiment includes information such as the identification information of the transmitter 5a. The transmitter 5a in this embodiment transmits multiple (three in the example of FIG. 9) radio signals RS1 to RS3 from three antennas 51. In the following description, the three radio signals RS1 to RS3 transmitted by the transmitter 5a may be simply referred to as "radio signals." Details of the transmitter 5a will be described in the section "(2.3) Configuration of the transmitter."

The acquisition unit 10 acquires information on the signal strength of three wireless signals RS1 to RS3 received by a receiver 2a (see FIG. 8A) present within the specified area A1. In other words, the acquisition unit 10 acquires information on the signal strength of four original signals BS1 to BS4 contained in the three wireless signals RS1 to RS3 received by the receiver 2a present within the specified area A1. The acquisition unit 10 acquires information on the signal strength of the three wireless signals RS1 to RS3 (the signal strength of the four original signals BS1 to BS4) from the receiver 2a by, for example, performing wireless communication with the receiver 2a within the specified area A1. The acquisition unit 10 outputs the signal strength information acquired from the receiver 2a to the estimation unit 3.

The estimation unit 3a estimates the position of the receiver 2a (see FIG. 8A) based on the signal strength information of the three radio signals RS1 to RS3 and the position information 41 and quasi-theoretical value information 42 stored in the memory unit 4a. Details of the estimation method by which the estimation unit 3a estimates the position of the receiver 2a will be explained in the section "(3) Estimation method."

The memory unit 4a stores position information 41 and quasi-theoretical value information 42. The position information 41 includes information indicating the positions of the transmitter 5a (estimation system 1a) and the reference receiver 9 (see FIG. 10) described later within the specified area A1 (see FIG. 8A). The quasi-theoretical value information 42 is information on a plurality of quasi-theoretical values that correspond one-to-one to position information indicating the positions of a plurality of candidate points P0 (36 in the example of FIG. 8A) for estimating the position of the receiver 2a within the specified area A1.

(2.2) Quasi-Theoretical Value Next, the quasi-theoretical value will be described in detail with reference to FIGS. 8A to 10. FIG.

As shown in Figure 10, the quasi-theoretical value in this embodiment is calculated in advance using a reference receiver 9 placed in a predetermined area A1. The reference receiver 9 is a device that receives three radio signals RS1 to RS3 (see Figure 9) transmitted by the transmitter 5a.

As shown in FIG. 10, when the transmitter 5a outputs a radio signal in a predetermined area A1 including a wall 6, which is a reflector, a part of the transmitted radio signal reaches the reference receiver 9 directly, and a part of the radio signal transmitted by the transmitter 5a is reflected by the wall 6 and reaches the reference receiver 9. In the example of FIG. 10, a part of the radio signal transmitted by the transmitter 5a is reflected by the reflection point 8 of the wall 64 and reaches the reference receiver 9. Therefore, the signal strength of the radio signal observed by the reference receiver 9 is the sum of the direct wave and the reflected wave. Here, the "direct wave" refers to the radio signal transmitted by the transmitter 5a that is directly transmitted from the transmitter 5a (i.e., without being reflected by a reflector such as the wall 6) and received by the reference receiver 9. The "reflected wave" refers to the radio signal transmitted by the transmitter 5a that is reflected by a reflector such as the wall 6 and then received by the reference receiver 9. In the example of Figure 10, of the radio signals emitted by transmitter 5a, the direct wave is the radio signal that passes through path a1 and is received by reference receiver 9, and the reflected wave is the radio signal that passes through paths a21 and a23 and is received by reference receiver 9.

The estimation system 1a can estimate the direction of arrival θ2 (see FIG. 8B) of the radio signal based on the signal strength of the radio signal received by the reference receiver 9, and can therefore estimate the path a0 of the radio signal which is the sum of the direct wave and the reflected wave. In this embodiment, the information indicating the position (coordinates) of the transmitter 5a and the information indicating the position of the reference receiver 9 are included in the position information 41. Therefore, the estimation system 1a can calculate the path a1 of the direct wave in the radio signal transmitted from the transmitter 5a based on the position information of the transmitter 5a and the reference receiver 9. The estimation system 1a can then calculate the path a2 of the reflected wave based on the path a0 of the radio signal which is the sum of the direct wave and the reflected wave, and the path a1 of the direct wave. The path a2 of the reflected wave in this embodiment is the path between the virtual reception point V9, which can be considered to have received the radio signal if there is no wall 62 (reflector), and the transmitter 5a. The virtual reception point V9 is located opposite the transmitter 5a via the reflection point 8 of the wall 64 that reflects the radio signal, and the length of the path a23 of the radio signal between the reflection point 8 and the reference receiver 9 is equal to the length of the path a22 of the radio signal between the reflection point 8 and the virtual reception point V9. The transmitter 5a, the reflection point 8 of the wall 64 that reflects the radio signal, and the virtual reception point V9 are aligned on a straight line. The position (coordinates) of the virtual reception point V9 is set based on position information indicating the position of the transmitter 5a, position information indicating the position of the reference receiver 9, and the signal strength of the radio signal when the reference receiver 9 receives the radio signal transmitted by the transmitter 5a.

The quasi-theoretical value is the sum of the path a1 of the radio signal between the candidate point P0 and the reference receiver 9, and the path a2 of the radio signal between the candidate point P0 and the virtual reception point V9 corresponding to the candidate point P0. The quasi-theoretical value information 42 is information that associates such a quasi-theoretical value with each candidate point P0. In other words, the quasi-theoretical value is a value that takes into account not only the direct wave received by the receiver 2a (see FIG. 8A) but also the reflected wave received by the receiver 2a, and is therefore a value that allows the estimation unit 3a (see FIG. 9) to estimate the position (coordinates) of the receiver 2a, rather than the position direction of the receiver 2a.

As described later, the estimation system 1a of this embodiment uses such a quasi-theoretical value as a steering vector to estimate the position of the receiver 2a within the specified area A1.

(2.3) Configuration of the Transmitter Next, the details of the transmitter 5a will be described with reference to FIG.

As shown in FIG. 9, the transmitter 5a has three antennas 51, a phase synthesis unit 52, and an original signal generation unit 54.

The original signal generating unit 54 is a processing unit that generates original signals BS1 to BS4, which are the source signals of the three radio signals RS1 to RS3 transmitted by the multiple antennas 51 and contain predetermined information such as identification information. The original signal generating unit 54 includes original signal generators 54a to 54d. The original signal generator 54a is electrically connected to the first input terminal I1 of the phase synthesizer 53d of the phase synthesizer unit 52 and generates the original signal BS1. The original signal generator 54b is electrically connected to the second input terminal I2 of the phase synthesizer 53d and generates the original signal BS2. The original signal generator 54c is electrically connected to the first input terminal I1 of the phase synthesizer 53e and generates the original signal BS3. The original signal generator 54d is electrically connected to the second input terminal I2 of the phase synthesizer 53e and generates the original signal BS4.

The phase synthesis unit 52 is a processing unit that performs synthesis processing on multiple (four in the example of Figure 9) input signals IS8 to IS11 (signals IS12 to IS15) based on the four original signals BS1 to BS4, and generates three radio signals RS1 to RS3.

The phase synthesizer 52 includes a phase synthesizer 53a, a phase synthesizer 53b, a phase synthesizer 53c, a phase synthesizer 53d, and a phase synthesizer 53e. In the following description, when the phase synthesizers 53a, 53b, 53c, 53d, and 53e are not distinguished from each other, they are simply referred to as a phase synthesizer 53. The phase synthesizer 53 is, for example, a 90-degree hybrid unit (hybrid element). The basic operation of the phase synthesizer 53 is the same as that of the phase synthesizer 23 described in the section "(2.3) Configuration of the receiver in (Embodiment 1)", and therefore will not be described here.

The phase synthesizer 53d receives the input signal IS8 at the first input terminal I1 and receives the input signal IS9 at the second input terminal I2. The phase synthesizer 53d outputs the signal IS12 from the first output terminal O1, which is obtained by adding together a signal whose power value is 1/√2 times the power of the input signal IS8 and whose phase is delayed by 90 degrees from the input signal IS9. The phase synthesizer 53d also outputs the signal IS13 from the second output terminal O2, which is obtained by adding together a signal whose power value is 1/√2 times the power of the input signal IS8 and whose phase is delayed by 90 degrees from the input signal IS8 and a signal whose power value is 1/√2 times the power of the input signal IS9 and whose phase is the same.

The phase synthesizer 53e receives the input signal IS10 at the first input terminal I1 and receives the input signal IS11 at the second input terminal I2. The phase synthesizer 53e outputs a signal IS14 from the first output terminal O1, which is obtained by adding together a signal whose power value is 1/√2 times the power of the input signal IS10 and whose phase is delayed by 90 degrees from the input signal IS11. The phase synthesizer 53e also outputs a signal IS15 from the second output terminal O2, which is obtained by adding together a signal whose power value is 1/√2 times the power of the input signal IS10 and whose phase is delayed by 90 degrees from the input signal IS11 and a signal whose power value is 1/√2 times the power of the input signal IS11 and whose phase is the same.

The phase synthesizer 53a outputs a radio signal RS1 from the second output terminal O2, which has a power value of 1/√2 times and is in phase with the signal IS12 input to the second input terminal I2.

The phase synthesizer 53b receives the signal IS13 at the first input terminal I1 and receives the signal IS14 at the second input terminal I2. The phase synthesizer 53b outputs the radio signal RS2 obtained by adding together a signal whose power value is 1/√2 times the power of the signal IS13 and whose phase is delayed by 90 degrees, and a signal whose power value is 1/√2 times the power of the signal IS14 and whose phase is the same, from the second output terminal O2.

The phase synthesizer 53c outputs a radio signal RS3 from the first output terminal O1, which has a power value of 1/√2 times and is in phase with the signal IS15 input to the first input terminal I1.

The three antennas 51 transmit three radio signals RS1 to RS3 output from the phase synthesis unit 52. Specifically, the antenna 51a transmits the radio signal RS1, the antenna 51b transmits the radio signal RS2, and the antenna 51c transmits the radio signal RS3.

(3) Estimation method Next, the estimation method by which the estimation unit 3a estimates the position of the receiver 2a within the predetermined area A1 will be described with reference to Figures 8A to 9. Note that the items described in the section "(3) Estimation method in (Embodiment 1)" will not be described as appropriate.

As shown in Figure 8B, the complex propagation channel between antenna 51a and the receiving antenna of receiver 2a is h4, the complex propagation channel between antenna 51b and the receiving antenna is h5, and the complex propagation channel between antenna 51c and the transmitting antenna is h6. The distance between antenna 51a and antenna 51b, and the distance between antenna 51b and antenna 51c are d2. The receiver 2a is located at an angle θ2 based on the broadside direction (X direction) of the array antenna composed of antennas 51a, 51b, and 51c.

The propagation channel can be collectively expressed as equation (27).

The correlation matrix of this propagation channel can be expressed as equation (27).

By calculating the correlation matrix R, the estimation unit 3a can estimate the position direction of the receiver 2a. The estimation unit 3a calculates the correlation matrix R based on information on the signal strength. Using the propagation channel of equation (27), the amplitudes of the four original signals BS1 to BS4 measured by the receiver 2a can be expressed as equations (29) to (32).

Here, if we use equation (33), the apparent propagation channel can be expressed by equations (34) to (37).

The method of calculating the correlation matrix R based on equations (34) to (37) and estimating receiver 2a using quasi-theoretical values is as explained in the section "(3) Estimation method in (embodiment 1)", so the explanation will be omitted.

(4) Effects As described above, the estimation system 1a according to this embodiment includes a transmitter 5a, an estimation unit 3, a storage unit 4a (first storage unit, second storage unit), and an acquisition unit 10. The storage unit 4a stores the position information 41 and the quasi-theoretical value information 42 in advance. The transmitter 5a performs phase synthesis processing on the four original signals BS1 to BS4 to generate three wireless signals RS1 to RS3, and transmits the three wireless signals RS1 to RS3 from three antennas 51. The acquisition unit 10 acquires information on the signal strength of the four original signals BS1 to BS4 received by the receiver 2a present in the predetermined area A1. The estimation unit 3a estimates the position of the receiver 2a in the predetermined area A1 based on the information on the signal strength of the four original signals BS1 to BS4, the position information of the multiple candidate points P0, and the multiple quasi-theoretical values that correspond one-to-one to the position information of the multiple candidate points P0. Since the multiple quasi-theoretical values correspond one-to-one to the position information of the multiple candidate points P0, the position of the receiver 2a can be estimated.

(5) Modifications As shown in Fig. 10, the quasi-theoretical value may be a value obtained by setting a virtual transmission point V10 instead of a virtual reception point V9. The virtual transmission point V10 is located opposite the reference receiver 9 via a reflection point 8 of a wall 64 that reflects a wireless signal, and is a virtual point that can be considered to have transmitted a reflected wave of the wireless signal if the wall 64 does not exist. Note that the virtual transmission point V10, the reflection point 8 of the wall 64 that reflects the wireless signal, and the reference receiver 9 are aligned on a straight line. In addition, the length of the path a24 of the wireless signal between the virtual transmission point V10 and the reflection point 8 is equal to the length of the path a21 of the wireless signal between the transmitter 5a and the reflection point 8. By setting the quasi-theoretical value after setting such a virtual transmission point V10, the quasi-theoretical value becomes a value that takes into account the path a2 of the reflected wave.

(summary)
As described above, the estimation system (1) according to the first aspect includes a receiver (2), an estimation unit (3), a first storage unit (storage unit 4), and a second storage unit (storage unit 4). The receiver (2) has a plurality of antennas (21). The plurality of antennas (21) receive radio signals transmitted from a transmitter (5). The receiver (2) performs phase synthesis processing on the radio signals received by the plurality of antennas (21) to generate a plurality of synthesis signals (SS1, SS2, SS3, SS4). The estimation unit (3) estimates the position of the transmitter (5) within a predetermined area (A1). The first storage unit (storage unit 4) stores a plurality of pieces of position information. The plurality of pieces of position information indicate a plurality of positions at a plurality of candidate points (P0) for estimating the position of the transmitter (5). The second storage unit (storage unit 4) stores a plurality of quasi-theoretical values. The plurality of quasi-theoretical values correspond one-to-one to each of the plurality of candidate points (P0). The plurality of quasi-theoretical values are values related to direct waves and reflected waves received by the receiver (2) when a wireless signal is transmitted from each of the plurality of candidate points (P0). The estimation unit (3) estimates the position of the transmitter (5) within the predetermined area (A1) based on the plurality of position information, the plurality of quasi-theoretical values, and the plurality of signal strengths in the plurality of composite signals (SS1, SS2, SS3, SS4).

According to this aspect, by estimating the position of the transmitter (5) based on multiple signal strengths and multiple quasi-theoretical values that correspond one-to-one to multiple pieces of position information of multiple candidate points (P0), the estimation unit (3) can estimate the position of the transmitter (5) based on, for example, a wireless signal received by one receiver (2). This makes it possible to reduce the number of antennas (21) when estimating the position of the target device (transmitter).

In the estimation system (1) relating to the second aspect, in the first aspect, the estimation unit (3) estimates the position of the transmitter (5) based on position information indicating the position of the candidate point (P0) among the multiple candidate points (P0) that corresponds to the quasi-theoretical value that has the highest correlation with the multiple signal intensities.

According to this aspect, the position of the transmitter (5) is estimated from the position information of the candidate point (P0) corresponding to the quasi-theoretical value that has the highest correlation with multiple signal strengths, thereby improving the estimation accuracy of the estimation system (1).

In the estimation system (1) according to the third aspect, in the first or second aspect, a reference transmitter (7) that transmits a reference signal is placed within a predetermined area (A1), and a virtual point is set based on location information indicating the location of the receiver (2), location information indicating the location of the reference transmitter (7), and the signal strength when the receiver (2) receives the reference signal. The virtual point is a virtual reception point (V1) or a virtual transmission point (V8). The virtual reception point (V1) is located opposite the reference transmitter (7) through a reflector (wall 6) that reflects the reference signal, and is a virtual point that can be considered to have received the reference signal if there is no reflector (wall 6). The virtual transmission point (V8) is located opposite the receiver (2) through a reflector (wall 6) that reflects the reference signal, and is a virtual point that can be considered to have transmitted the reference signal to the receiver (2) if there is no reflector (wall 6). The multiple quasi-theoretical values are the sum of the path (a1) of the radio signal between each of the multiple candidate points (P0) and the receiver (2) and the path (a2) of the radio signal between each of the multiple candidate points (P0) and the virtual reception point (V1), or the path (a2) of the radio signal between the receiver (2) and the virtual transmission point (V8).

According to this aspect, since the multiple quasi-theoretical values are the sum of the direct wave path (a1) and the reflected wave path (a2), the estimation unit (3) can estimate the position of the transmitter (5) from a radio signal received by, for example, one receiver (2).

In the estimation system (1) according to the fourth aspect, in the third aspect, the virtual point is a virtual reception point (V1). The distance between the virtual reception point (V1) and the reflector (wall 6) is equal to the distance between the receiver (2) and the reflector (wall 6).

According to this aspect, the distance between the virtual receiving point (V1) and the reflector (wall 6) is equal to the distance between the receiver (2) and the reflector (wall 6), improving the accuracy with which the estimation unit (3) estimates the position of the transmitter (5).

In the estimation system (1) according to the fifth aspect, in the third aspect, the virtual point is the virtual transmission point (V8). The distance between the virtual transmission point (V8) and the reflector (wall 6) is equal to the distance between the reference transmitter (7) and the reflector (wall 6).

According to this embodiment, the distance between the virtual transmission point (V8) and the reflector (wall 6) is equal to the distance between the reference transmitter (7) and the reflector (wall 6), improving the accuracy with which the estimation unit (3) estimates the position of the transmitter (5).

In the estimation system (1) according to the sixth aspect, in any one of the third to fifth aspects, a plurality of virtual reception points (V1) or virtual transmission points (V8) are set for the reference transmitter (7). Between the plurality of virtual reception points (V1) and the reference transmitter (7), or between the plurality of virtual transmission points (V8) and the receiver (2), there are a plurality of reflectors (walls 61, 62, 63, and 64) that reflect the reference signal. The plurality of quasi-theoretical values are the sum of a plurality of paths (a1) between each of the plurality of candidate points (P0) and the receiver (2), and a plurality of paths (a2) of the radio signal between each of the plurality of candidate points (P0) and the plurality of virtual reception points (V1), or a plurality of paths (a2) of the radio signal between the receiver (2) and the plurality of virtual transmission points (V8).

According to this aspect, since the paths (a2) of multiple reflected waves are added together, the estimation unit (3) can estimate the position of the transmitter (5) more accurately than when there is only one virtual point.

In the estimation system (1) according to the seventh aspect, in any one of the third to fifth aspects, a plurality of reference transmitters (7) are arranged within a predetermined area (A1), and a virtual reception point (V1) or a virtual transmission point (V8) is set for each of the plurality of reference transmitters (7a, 7b, 7c, 7d). Between the plurality of reference transmitters (7a, 7b, 7c, 7d) and the plurality of virtual reception points (V1), or between the plurality of virtual transmission points (V8) and the receiver (2), there are a plurality of reflectors (walls 61, 62, 63, 64) that reflect the reference signal. The multiple quasi-theoretical values are the sum of multiple paths (a1) between each of the multiple candidate points (P0) and the receiver (2), and multiple paths (a2) of the radio signal between each of the multiple candidate points (P0) and multiple virtual reception points (V1), or multiple paths (a2) of the radio signal between the receiver (2) and multiple virtual transmission points (V8).

According to this aspect, since the multiple quasi-theoretical values are the sum of the paths (a2) of the multiple reflected waves, the estimation unit (3) can estimate the position of the transmitter (5) more accurately than when there is only one virtual point.

In the estimation system (1) relating to the eighth aspect, in the sixth or seventh aspect, the multiple quasi-theoretical values are the sum of multiple radio signal paths (a1) between each of the multiple candidate points (P0) and the receiver (2) and all of the multiple radio signal paths (a2) between each of the multiple candidate points (P0) and multiple virtual reception points (V1), or all of the multiple radio signal paths (a2) between the receiver (2) and multiple virtual transmission points (V8).

According to this aspect, the multiple quasi-theoretical values are the sum of all the multiple reflected wave paths (a2), so that the estimation unit (3) can estimate the position of the transmitter (5) with greater accuracy.

In the estimation system (1) according to the ninth aspect, in any one of the third to eighth aspects, the position information of the multiple candidate points (P0), the position information of the receiver (2), and the position information of the reference transmitter (7) are position information indicating three-dimensional positions within the predetermined area (A1). The virtual point is set by the position information indicating the three-dimensional position.

According to this aspect, the estimation unit (3) can estimate the three-dimensional position of the transmitter (5) based on position information indicating the three-dimensional position.

Configurations other than the first aspect are not essential to the estimation system (1) and may be omitted as appropriate.

The estimation system (1a) according to the tenth aspect includes a transmitter (5a), an acquisition unit (10), an estimation unit (3a), a first storage unit (storage unit 4a), and a second storage unit (storage unit 4a). The transmitter (5a) performs phase synthesis processing on a plurality of original signals (BS1, BS2, BS3, BS4) to generate a plurality of wireless signals (RS1, RS2, RS3), and transmits the plurality of wireless signals (RS1, RS2, RS3) from a plurality of antennas (51). The acquisition unit (10) acquires information on the signal strength of a plurality of wireless signals (RS1, RS2, RS3) received by a receiver (2a) present within a predetermined area (A1). The estimation unit (3a) estimates the position of the receiver (2a) within the predetermined area (A1). The first storage unit stores a plurality of pieces of position information. The multiple pieces of position information indicate multiple positions at multiple candidate points (P0) for estimating the position of the receiver (2). The second memory unit stores multiple quasi-theoretical values. The multiple quasi-theoretical values correspond one-to-one with each of the multiple candidate points (P0). The multiple quasi-theoretical values are values related to direct waves and reflected waves received by the receiver (2a) when a wireless signal is received at each of the multiple candidate points (P0). The estimation unit (3a) estimates the position of the receiver (2a) within the specified area (A1) based on the multiple pieces of position information, the multiple quasi-theoretical values, and multiple pieces of signal strength information acquired by the acquisition unit (10).

According to this aspect, by estimating the position of the receiver (2a) based on a plurality of pieces of signal strength information and a plurality of quasi-theoretical values that correspond one-to-one to each of a plurality of pieces of position information at a plurality of candidate points (P0), the estimation unit (3a) can estimate the position of the receiver (2a) based on the signal strengths of a plurality of wireless signals (RS1, RS2, RS3) transmitted by one transmitter (5a), for example. This makes it possible to reduce the number of antennas (51) required when estimating the position of the target device (receiver).

The estimation method according to the eleventh aspect includes a receiving step, a generating step, and an estimating step. In the receiving step, a radio signal transmitted by a transmitter (5) is received by a plurality of antennas (21). In the generating step, a phase synthesis process is performed on the radio signal received in the receiving step to generate a plurality of synthesized signals (SS1, SS2, SS3, SS4). In the estimating step, the position of the transmitter (5) within a predetermined region (A1) is estimated. In the estimating step, the position of the transmitter (5) within a predetermined region (A1) is estimated based on a plurality of pieces of position information, a plurality of quasi-theoretical values, and a plurality of signal intensities in the plurality of synthesized signals (SS1, SS2, SS3, SS4). The plurality of pieces of position information indicate the positions of a plurality of candidate points (P0) for estimating the position of the transmitter (5) within the predetermined region (A1). The plurality of pieces of position information are information stored in advance. The plurality of quasi-theoretical values correspond one-to-one to each of the plurality of pieces of position information. The plurality of quasi-theoretical values are values related to direct waves and reflected waves received by the plurality of antennas (21) when a wireless signal is transmitted from each of the plurality of candidate points (P0). The plurality of quasi-theoretical values are stored in advance.

According to this aspect, the position of the transmitter (5) can be estimated based on a plurality of signal strengths and a plurality of quasi-theoretical values that correspond one-to-one to each of the plurality of position information at the plurality of candidate points (P0), so that the position of the transmitter (5) can be estimated based on, for example, a radio signal received by one receiver (2). This makes it possible to reduce the number of antennas (21) when estimating the position of the target device (transmitter).

The estimation method according to the twelfth aspect includes a first receiving step, a setting step, a storage step, a second receiving step, and an estimation step. In the first receiving step, the receiver (2) receives direct waves and reflected waves of a reference signal transmitted by a reference transmitter (7) installed within a predetermined area (A1). The receiver (2) has a plurality of antennas (21). In the setting step, a virtual reception point (V1) or a virtual transmission point (V8) is set based on the position information of the receiver (2) and the reference transmitter (7) and the signal strength of the reference signal. The virtual reception point (V1) can be regarded as having received a reflected wave. The virtual transmission point (V8) can be regarded as having transmitted a reflected wave. In the storage step, a plurality of quasi-theoretical values are stored in the storage unit (4) based on the position information of the receiver (2) and the position information of the virtual reception point (V1) or the virtual transmission point (V8). The multiple quasi-theoretical values are values related to direct waves and reflected waves received by the receiver (2) when the transmitter (5) transmits a wireless signal at each of multiple candidate points (P0) within the predetermined region (A1). In the second receiving step, the wireless signal transmitted by the transmitter (5) is received by the receiver (2). In the estimation step, the position of the candidate point (P0) corresponding to the multiple quasi-theoretical value that has the highest correlation with the signal strength of the wireless signal received by the receiver (2) in the second receiving step is estimated to be the position of the transmitter (5).

According to this aspect, the position of the transmitter (5) can be estimated based on a plurality of signal strengths and a plurality of quasi-theoretical values that correspond one-to-one to each of the plurality of position information at the plurality of candidate points (P0), so that the position of the transmitter (5) can be estimated based on, for example, a radio signal received by one receiver (2). This makes it possible to reduce the number of antennas (21) when estimating the position of the target device (transmitter).

The program of the 13th aspect is a program for causing one or more processors to execute the estimation method of the 11th or 12th aspect.

According to this aspect, the position of the transmitter (5) can be estimated based on a plurality of signal strengths and a plurality of quasi-theoretical values that correspond one-to-one to the position information of each of the plurality of candidate points (P0), so that the position of the transmitter (5) can be estimated based on, for example, a radio signal received by one receiver (2). This makes it possible to reduce the number of antennas (21) required when estimating the position of the target device (transmitter).

1, 1a Estimation system 2, 2a Receiver 21 Antenna 3, 3a Estimation unit 4, 4a Memory unit (first memory unit, second memory unit)
41 Location information 5, 5a Transmitter 51 Antenna 6 Wall (reflector)
7 Reference transmitter 10 Acquisition unit A1 Predetermined area P0 Candidate point V1 Virtual reception point V8 Virtual transmission point

Claims (12)

a receiver having a plurality of antennas for receiving radio signals transmitted from a transmitter, the receiver performing phase synthesis processing on the radio signals received by the plurality of antennas to generate a plurality of synthesized signals;
an estimation unit that estimates a position of the transmitter within a predetermined area;
a first storage unit that stores a plurality of pieces of position information indicating positions of a plurality of candidate points for estimating the position of the transmitter;
a second storage unit that stores a plurality of quasi-theoretical values that correspond one-to-one to each of the plurality of pieces of position information and are values related to a direct wave and a reflected wave that are received by the receiver when a wireless signal is transmitted from each of the plurality of candidate points;
Equipped with
the estimation unit estimates a position of the transmitter within the predetermined area based on the plurality of pieces of position information, the plurality of quasi-theoretical values, and a plurality of signal intensities of the plurality of composite signals;
a reference transmitter that transmits a reference signal is disposed within the predetermined area, and a virtual point is set based on position information indicating a position of the receiver, position information indicating a position of the reference transmitter, and a signal strength when the reference signal is received by the receiver;
The virtual point is
a virtual reception point that is located opposite the reference transmitter via a reflector that reflects the reference signal, and that can be regarded as having received the reference signal if the reflector does not exist, or a virtual transmission point that is located opposite the receiver via a reflector that reflects the reference signal, and that can be regarded as having transmitted the reference signal to the receiver if the reflector does not exist,
The plurality of quasi-theoretical values are a sum of a path of a wireless signal between each of the plurality of candidate points and the receiver, and a path of a wireless signal between each of the plurality of candidate points and the virtual reception point, or a path of a wireless signal between the receiver and the virtual transmission point.
Estimation system. the estimation unit estimates the position of the transmitter based on position information indicating a position of a candidate point corresponding to a quasi-theoretical value having a highest correlation with the plurality of signal intensities among the plurality of candidate points;
The estimation system of claim 1 . the virtual point is the virtual reception point,
The distance between the virtual receiving point and the reflector is equal to the distance between the receiver and the reflector.
The estimation system according to claim 1 or 2. the virtual point is the virtual transmission point,
the distance between the virtual transmission point and the reflector is equal to the distance between the reference transmitter and the reflector;
The estimation system according to claim 1 or 2. A plurality of the virtual reception points or the virtual transmission points are set for the reference transmitter,
a plurality of reflectors that reflect the reference signal are provided between the plurality of virtual reception points and the reference transmitter, or between the plurality of virtual transmission points and the receiver;
The plurality of quasi-theoretical values are a sum of the plurality of paths between each of the plurality of candidate points and the receiver, and a plurality of paths of a wireless signal between each of the plurality of candidate points and the plurality of virtual reception points, or a plurality of paths of a wireless signal between the receiver and the plurality of virtual transmission points.
The estimation system according to any one of claims 1 to 4. A plurality of the reference transmitters are arranged within the predetermined area, and the virtual reception point or the virtual transmission point is set for each of the plurality of the reference transmitters;
a plurality of reflectors that reflect the reference signal are provided between the plurality of reference transmitters and the plurality of virtual reception points, or between the plurality of virtual transmission points and the receiver;
The plurality of quasi-theoretical values are a sum of the plurality of paths between each of the plurality of candidate points and the receiver, and a plurality of paths of a wireless signal between each of the plurality of candidate points and the plurality of virtual reception points, or a plurality of paths of a wireless signal between the receiver and the plurality of virtual transmission points.
The estimation system according to any one of claims 1 to 4. The plurality of quasi-theoretical values are a sum of the plurality of paths of the wireless signal between each of the plurality of candidate points and the receiver, and all of the plurality of paths of the wireless signal between each of the plurality of candidate points and the plurality of virtual reception points, or all of the plurality of paths of the wireless signal between the receiver and the plurality of virtual transmission points.
The estimation system according to claim 5 or 6. the plurality of position information of the plurality of candidate points, the position information of the receiver, and the position information of the reference transmitter are position information indicating three-dimensional positions within the predetermined area,
The virtual point is set by position information indicating a three-dimensional position.
The estimation system according to any one of claims 1 to 7. a transmitter that performs phase synthesis processing on a plurality of original signals to generate a plurality of radio signals and transmits the plurality of radio signals from a plurality of antennas;
an acquisition unit that acquires information on a plurality of signal intensities of the plurality of wireless signals received by a receiver present within a predetermined area;
an estimation unit that estimates a position of the receiver within the predetermined area;
a first storage unit configured to store a plurality of pieces of position information at a plurality of candidate points for estimating a position of the receiver;
a second storage unit that stores in advance a plurality of quasi-theoretical values that correspond one-to-one to each of the plurality of pieces of position information and are values related to a direct wave and a reflected wave that are received by the receiver when a wireless signal is received at each of the plurality of candidate points;
Equipped with
the estimation unit estimates a position of the receiver within the predetermined area based on the plurality of pieces of position information, the plurality of quasi-theoretical values, and the plurality of pieces of signal strength information acquired by the acquisition unit;
a reference receiver for receiving the plurality of wireless signals is disposed within the predetermined area, and a virtual point is set based on location information indicating a location of the transmitter, location information indicating a location of the reference receiver, and signal strengths of the plurality of wireless signals when received by the reference receiver;
The virtual point is
a virtual reception point that is located opposite the transmitter via a reflector that reflects the multiple radio signals, and that can be regarded as having received the multiple radio signals in the absence of the reflector, or a virtual transmission point that is located opposite the reference receiver via a reflector that reflects the multiple radio signals, and that can be regarded as having transmitted the multiple radio signals to the reference receiver in the absence of the reflector,
the plurality of quasi-theoretical values are a sum of a path of a radio signal between each of the plurality of candidate points and the reference receiver, and a path of a radio signal between each of the plurality of candidate points and the virtual reception point, or a path of a radio signal between the reference receiver and the virtual transmission point;
Estimation system. a receiving step of receiving a radio signal transmitted from a transmitter by a receiver having a plurality of antennas;
a generating step of generating a plurality of composite signals by performing phase synthesis processing on the wireless signals received in the receiving step;
an estimation step of estimating a position of the transmitter within a predetermined area;
having
In the estimation step,
A plurality of pieces of pre-stored position information indicating positions of a plurality of candidate points for estimating the position of the transmitter within the predetermined area; and
a plurality of quasi-theoretical values that correspond one-to-one to each of the plurality of pieces of position information, and are values related to a direct wave and a reflected wave that are received by the receiver when the wireless signal is transmitted at each of the plurality of candidate points, and that are stored in advance;
a plurality of signal strengths in the plurality of composite signals;
and estimating the position of the transmitter within the predetermined area based on the
a reference transmitter that transmits a reference signal is disposed within the predetermined area, and a virtual point is set based on position information indicating a position of the receiver, position information indicating a position of the reference transmitter, and a signal strength when the reference signal is received by the receiver;
The virtual point is
a virtual reception point that is located opposite the reference transmitter via a reflector that reflects the reference signal, and that can be regarded as having received the reference signal if the reflector does not exist, or a virtual transmission point that is located opposite the receiver via a reflector that reflects the reference signal, and that can be regarded as having transmitted the reference signal to the receiver if the reflector does not exist,
The plurality of quasi-theoretical values are a sum of a path of a wireless signal between each of the plurality of candidate points and the receiver, and a path of a wireless signal between each of the plurality of candidate points and the virtual reception point, or a path of a wireless signal between the receiver and the virtual transmission point.
Estimation method. a first receiving step of receiving, by a receiver having a plurality of antennas, a direct wave and a reflected wave of a reference signal transmitted by a reference transmitter installed within a predetermined area;
a setting step of setting a virtual reception point at which the reflected wave can be regarded as having been received or a virtual transmission point at which the reflected wave can be regarded as having been transmitted, based on position information of the receiver and the reference transmitter and the signal strength of the reference signal;
a storage step of calculating in advance a plurality of quasi-theoretical values related to a direct wave and a reflected wave received by the receiver when a transmitter transmits a wireless signal at each of a plurality of candidate points within the predetermined area based on position information of the receiver and position information of the virtual reception point or the virtual transmission point, and storing the calculated values in a storage unit;
a second receiving step of receiving, by the receiver, a radio signal transmitted by a transmitter;
an estimation step of estimating, as the position of the transmitter, a position of a candidate point corresponding to a quasi-theoretical value having the highest correlation with the signal strength of the wireless signal received by the receiver in the second receiving step, among the plurality of quasi-theoretical values;
having
Estimation method. A program for causing one or more processors to execute the estimation method according to claim 10 or 11.

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