First-class radio device, second-class radio device, radio ranging system, communication method, and program

Abstract

To provide a technique of wireless communication for measuring the distance between two radio devices capable of suppressing traffic increase.SOLUTION: A communication unit 102 is capable of executing a wireless communication. A control unit 160 executes a series of connection processing between the communication unit 102 and a tag 200. A rangefinder 140 is configured so as to, when the communication unit 102 is connected to the tag 200 due to the connection processing by the control unit 160, measure the distance to the tag 200 due to the wireless communication between the communication unit 102 and the tag 200. The control unit 160 is configured to release the connection between the communication unit 102 and the tag 200 when a first condition is met after the wireless communication between the communication unit 102 and the tag 200 has been performed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a measurement technique, and more particularly to a first type wireless device, a second type wireless device, a wireless ranging system, a communication method, and a program for measuring the distance between two devices. [Background technology]

[0002] In order to measure the distance between two wireless devices, wireless communication is performed between the two wireless devices. For example, a carrier signal is transmitted from a first wireless device (hereinafter referred to as a "first wireless device") to a second wireless device (hereinafter referred to as a "second wireless device"), and a carrier signal is also transmitted from the second wireless device to the first wireless device. Based on the reception result at the first wireless device and the reception result at the second wireless device, the distance between the first wireless device and the second wireless device is measured (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-155724 A Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple first wireless devices and multiple second wireless devices are included, the traffic of wireless communication between the two wireless devices increases.

[0005] The present disclosure has been made in consideration of these circumstances, and has an object to provide a technique for suppressing an increase in traffic in wireless communication for measuring the distance between two wireless devices. [Means for solving the problem]

[0006] In order to solve the above problem, a first type radio device according to an embodiment of the present disclosure includes a communication unit capable of performing wireless communication, a control unit that executes a connection process between the communication unit and the second type radio device, and a distance measurement unit that measures the distance between the communication unit and the second type radio device through wireless communication between the communication unit and the second type radio device when the communication unit is connected to the second type radio device through the connection process by the control unit. When a first condition is satisfied after wireless communication between the communication unit and the second type radio device is performed, the control unit cancels the connection between the communication unit and the second type radio device. The distance measuring unit measures the distance based on a reception result received from the second type radio device regarding the signal transmitted from the first type radio device to the second type radio device and the signal received from the second type radio device. . Another aspect of the present disclosure is also a first type radio device. This device is a first type radio device, and includes a communication unit capable of performing wireless communication, a control unit that executes a connection process between the communication unit and a second type radio device, and a distance measuring unit that measures the distance between the second type radio device through wireless communication between the communication unit and the second type radio device when the communication unit is connected to the second type radio device through the connection process by the control unit. When a first condition is satisfied after wireless communication between the communication unit and the second type radio device is performed, the control unit releases the connection between the communication unit and the second type radio device, and the control unit determines the interval of the report signal periodically transmitted from the second type radio device according to the period after the distance measuring unit measures the distance.

[0007] The present disclosure moreover Another aspect is a second type radio device. This device is a second type radio device capable of wireless communication with a first type radio device, and includes a communication unit capable of wireless communication, and a control unit that executes a connection process between the communication unit and the first type radio device. When the communication unit is connected to the first type radio device through a connection process by the control unit, the communication unit executes wireless communication between the communication unit and the first type radio device to cause the first type radio device to measure the distance between the first type radio device and the second type radio device, and when a third condition is satisfied after wireless communication between the communication unit and the first type radio device is established, the control unit releases the connection between the communication unit and the first type radio device. The communication unit transmits a reception result of the signal received from the first type radio device and a signal to the first type radio device in order to cause the first type radio device to measure the distance between the first type radio device and the second type radio device. .

[0008] Yet another aspect of the present disclosure is a communication method in a first type wireless device capable of performing wireless communication, the method including the steps of: executing a connection process between the first type wireless device and a second type wireless device; when the first type wireless device is connected to the second type wireless device by the connection process, measuring a distance between the second type wireless device through wireless communication between the first type wireless device and the second type wireless device; and, when a first condition is satisfied after wireless communication between the first type wireless device and the second type wireless device is performed, releasing the connection between the first type wireless device and the second type wireless device. The measuring step measures the distance based on a reception result received from the second type radio device regarding a signal transmitted from the first type radio device to the second type radio device and a signal received from the second type radio device. . Yet another aspect of the present disclosure is also a communication method in a first type wireless device capable of wireless communication, the method including the steps of: executing a connection process between the first type wireless device and a second type wireless device; when the first type wireless device is connected to the second type wireless device by the connection process, measuring the distance between the second type wireless device by wireless communication between the first type wireless device and the second type wireless device; when a first condition is satisfied after wireless communication between the first type wireless device and the second type wireless device is performed, canceling the connection between the first type wireless device and the second type wireless device; and determining the interval of a report signal periodically transmitted from the second type wireless device according to a period after a distance measuring unit measures the distance.

[0009] Yet another aspect of the present disclosure is also a communication method in a second type radio device capable of performing wireless communication with a first type radio device, the method including the steps of: executing a connection process between the second type radio device and the first type radio device; when the second type radio device is connected to the first type radio device by the connection process, executing wireless communication between the second type radio device and the first type radio device to cause the first type radio device to measure the distance between the first type radio device and the second type radio device; and, after the wireless communication between the second type radio device and the first type radio device is performed, when a third condition is satisfied, releasing the connection between the second type radio device and the first type radio device. The step of performing wireless communication includes transmitting a reception result of a signal from the first type wireless device and a signal to the first type wireless device so that the first type wireless device measures a distance between the first type wireless device and the second type wireless device. .

[0010] Any combination of the above components, and conversion of the present disclosure into a method, device, system, recording medium, computer program, etc. are also valid aspects of the present disclosure. Effect of the Invention

[0011] According to the present disclosure, it is possible to suppress an increase in traffic in wireless communication for measuring the distance between two wireless devices. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a wireless ranging system according to a first embodiment. [Diagram 2] 2(a) and (b) are diagrams showing the configurations of the scanner, tag, and position estimation device in the wireless ranging system of FIG. [Diagram 3] 3(a)-(b) are diagrams showing the format of a signal used in the wireless ranging system of FIG. [Figure 4] 2 is a sequence diagram showing a communication procedure of the wireless ranging system of FIG. 1. [Diagram 5] 5(a) and 5(b) are diagrams showing other configurations of the tag and scanner in the wireless ranging system of FIG. [Figure 6]6(a)-(b) are flow charts showing a communication procedure using the scanner of FIG. 2(a) or the scanner of FIG. 5(b). [Figure 7] 7(a) and (b) are diagrams showing the configuration of a tag and a scanner according to the second embodiment. [Figure 8] 8(a)-(b) are flow charts showing a communication procedure using the scanner of FIG. 2(a) or the scanner of FIG. 7(b). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Example 1 Before describing the present disclosure in detail, an overview will be provided. Example 1 relates to a wireless ranging system that measures the distance between two wireless devices. The wireless devices included in the wireless ranging system are, for example, a scanner and a tag. The scanner transmits a measurement signal to the tag. The tag generates a reception result of the measurement signal (hereinafter referred to as "first reception data"). The tag transmits the measurement signal and the first reception data to the scanner. The scanner generates a reception result of the measurement signal (hereinafter referred to as "second reception data"). The scanner averages the first reception data and the second reception data to generate reception data, and measures the distance by a MUSIC (MUltiple SIgnal Classification) method based on the reception data. Furthermore, the wireless ranging system includes multiple scanners with fixed positions, and the position of the tag is estimated based on the distance to the tag measured by each scanner.

[0014] In the case where a wireless ranging system includes multiple tags, when a measurement signal transmitted from one scanner is received by multiple tags, each of the multiple tags transmits the first reception data to the scanner. Therefore, the scanner may transmit the first reception data from a tag that is not a target for distance measurement. As the number of scanners and tags included in the wireless ranging system increases, the traffic increases due to the increase in unnecessary first reception data.

[0015] In this embodiment, the tag periodically broadcasts a signal (hereinafter, referred to as "advertisement") to notify the presence of the tag. The scanner recognizes the presence of the tag by receiving the advertisement. When the scanner determines the tag to be the target of distance measurement, it transmits a connection request to the tag, thereby executing a connection process between the scanner and the tag. Subsequently, a measurement signal is transmitted between the scanner and the tag, and the scanner measures the distance. After the distance measurement is completed, the scanner transmits a disconnection request to the tag, thereby executing a disconnection process between the scanner and the tag. In other words, the scanner and the tag execute a connection process and a disconnection process when measuring the distance, and therefore the scanner and the tag communicate wirelessly one-to-one. The one-to-one wireless communication between the scanner and the tag suppresses an increase in traffic.

[0016] In this embodiment, if the processing conditions are further met, the scanner does not execute a disconnection process on the tag even after the distance measurement is completed. This allows a measurement signal to be transmitted between the scanner and the tag without executing a connection process between the scanner and the tag. As a result, the increase in traffic is suppressed by omitting the disconnection process and the connection process.

[0017] Here, the principle of position estimation of the tag 200 by the wireless ranging system 1000 will be explained, and then the processing in the wireless ranging system 1000 will be explained. FIG. 1 shows the configuration of the wireless ranging system 1000. The wireless ranging system 1000 includes a first scanner 100a to a fourth scanner 100d collectively referred to as scanners 100, a first tag 200a and a second tag 200b collectively referred to as tags 200, and a position estimation device 300. The number of scanners 100 included in the wireless ranging system 1000 is not limited to "4", and the number of tags 200 is not limited to "2". When the scanner 100 is referred to as a first type wireless device, the tag 200 is referred to as a second type wireless device.

[0018] The position of each scanner 100 is fixed, and the scanner 100 has a wireless communication function with the tag 200. For example, the first scanner 100a and the first tag 200a perform wireless communication with each other, whereby the first scanner 100a measures the distance between the first scanner 100a and the first tag 200a (hereinafter referred to as the "first distance"). The second scanner 100b and the first tag 200a perform wireless communication with each other, whereby the second scanner 100b measures the distance between the second scanner 100b and the first tag 200a (hereinafter referred to as the "second distance"). The third scanner 100c and the first tag 200a perform wireless communication with each other, whereby the third scanner 100c measures the distance between the third scanner 100c and the first tag 200a (hereinafter referred to as the "third distance"). Each scanner 100 can communicate with the position estimation device 300 by wire or wirelessly, and transmits information on the measured distance to the position estimation device 300.

[0019] The position estimation device 300 receives distance information from each scanner 100. The position estimation device 300 also stores position information where each scanner 100 is fixed. The position information is indicated by, for example, latitude and longitude. The position estimation device 300 estimates the position of the first tag 200a by performing triangulation based on the first distance, the second distance, the third distance, and the respective position information of the first scanner 100a to the third scanner 100c. A similar process is performed for the second tag 200b.

[0020] 2(a)-(b) show the configurations of the scanner 100, tag 200, and position estimation device 300 in a wireless ranging system 1000. Fig. 2(a) shows the configurations of the scanner 100 and tag 200. The scanner 100 includes a communication unit 102, a derivation unit 130, a distance measurement unit 140, an external communication unit 150, and a control unit 160, and the communication unit 102 includes a transmission unit 110 and a reception unit 120. The tag 200 includes a communication unit 202 and a derivation unit 230, and the communication unit 202 includes a transmission unit 210 and a reception unit 220. The scanner 100 is a device that executes a process of measuring distance, and the tag 200 is a device to be measured for distance.

[0021] The transmitter 110 of the scanner 100 transmits to the tag 200 a first measurement signal to be used for measuring the reception environment of the tag 200, and a trigger signal indicating the timing of transmitting the first measurement signal. Figures 3(a)-(b) show the formats of signals used in the wireless ranging system 1000. Figure 3(a) shows the format of the signal transmitted from the transmitter 110. A trigger signal is placed at the beginning of the signal. The trigger signal has a predetermined pattern, which indicates that the first measurement signal will be placed following it. The first measurement signal contains a number of mutually different frequencies "f1", "f2", ..., "f K The unmodulated waves are time-division multiplexed. The frequency intervals of the unmodulated waves are equal. The first measurement signal is divided into "f1", "f2", ..., "f n-1 ", "f n+1 ",..., "f K ", a specific frequency "f n " may be omitted from the beginning. FIG. 3(b) will be described later, so let us return to FIG.

[0022] The receiver 220 of the tag 200 receives the trigger signal and the first measurement signal from the scanner 100. The receiver 220 operates asynchronously with the transmitter 110. The receiver 220 recognizes the reception of the first measurement signal by receiving the trigger signal. The derivation unit 230 derives a reception result for each of the unmodulated waves of multiple frequencies included in the first measurement signal received by the receiver 220. Each reception result is the result of quadrature detection in the receiver 220, and is complex data including an in-phase component and a quadrature component. A combination of the reception results for each of the multiple frequencies corresponds to the first reception data described above. The first reception data indicates the reception environment measured by the tag 200 based on the first measurement signal at the transmission timing indicated by the trigger signal.

[0023] The transmitting unit 210 transmits to the scanner 100 the first received data derived in the derivation unit 230 and a second measurement signal to be used for measuring the reception environment in the scanner 100. FIG. 3(b) shows the format of the signal transmitted from the transmitting unit 210. The first received data is placed at the beginning of the signal. The second measurement signal is placed following the first received data. The second measurement signal contains a plurality of mutually different frequencies "f1", "f2", ..., "f K " unmodulated waves are time-division multiplexed. The frequency intervals of the unmodulated waves are equal. Return to Figure 2.

[0024] The receiving unit 120 of the scanner 100 receives the first reception data and the second measurement signal from the tag 200. The receiving unit 120 operates asynchronously with the transmitting unit 210. The receiving unit 120 outputs the first reception data to the distance measuring unit 140. The derivation unit 130 derives a reception result for each of the unmodulated waves of multiple frequencies included in the second measurement signal received by the receiving unit 220. Each reception result is a result of quadrature detection in the receiving unit 120, and is complex data including an in-phase component and a quadrature component. A combination of the reception results for each of the multiple frequencies corresponds to the second reception data described above. The second reception data indicates the reception environment measured by the scanner 100 based on the second measurement signal. The derivation unit 130 outputs the second reception data to the distance measuring unit 140.

[0025] The distance measuring unit 140 receives the second reception data derived in the derivation unit and the first reception data received in the reception unit. As described above, the first reception data and the second reception data include components corresponding to each of a plurality of frequencies and are complex data. The distance measuring unit 140 generates reception data based on the first reception data and the second reception data by associating the first reception data and the second reception data with each component and then calculating the average for each component. Therefore, the reception data also has components corresponding to each of a plurality of frequencies. As described above, the transmission unit 110 and the reception unit 220 are not synchronized, and the reception unit 120 and the transmission unit 210 are not synchronized, so the scanner 100 and the tag 200 operate asynchronously. Therefore, each of the first reception data and the second reception data includes a component of synchronization deviation, and the first reception data and the second reception data do not show phase information according to the distance. However, the first received data includes a component of misalignment of the tag 200 with respect to the scanner 100, and the second received data includes a component of misalignment of the scanner 100 with respect to the tag 200. By averaging the first received data and the second received data, the misalignment is cancelled out, and phase information according to distance can be obtained.

[0026] The distance measurement unit 140 measures the distance to the tag 200 using the MUSIC algorithm based on the received data. If the number of components included in the received data is K, the received data X(t) at time t is expressed as follows:

number

number

number

[0027] Correlation matrix R of received data xx can be shown as follows:

number

number

[0028] The mode vector a(r i ) can be expressed as follows:

number

number

[0029] Therefore, the MUSIC evaluation function P MUSIC can be shown as follows:

number

[0030] The external communication unit 150 is connected to the position estimation device 300 in Fig. 1 by wire or wirelessly, and can communicate with the position estimation device 300. The external communication unit 150 transmits information on the distance measured by the distance measurement unit 140 to the position estimation device 300. At that time, identification information for identifying the scanner 100 (hereinafter referred to as "scanner ID") and identification information for identifying the tag 200 whose distance has been measured (hereinafter referred to as "tag ID") are also transmitted. The control unit 160 controls the operation of the scanner 100, and the control unit 260 controls the operation of the tag 200.

[0031] 2(b) shows the configuration of the position estimation device 300. The position estimation device 300 includes a distance storage unit 310 and a position estimation unit 320. The distance storage unit 310 receives distance information from each scanner 100 by communicating with each scanner 100. The distance storage unit 310 stores a scanner ID, a tag ID, and a distance in association with each other. The distance storage unit 310 also stores the scanner ID of each scanner 100 and information on the position where the scanner 100 is fixed in association with each other.

[0032] The position estimation unit 320 extracts three or more combinations, for example three, of scanner ID, tag ID, and distance from the distance storage unit 310, each including one tag ID of the estimation target. The position estimation unit 320 also extracts position information of the scanner ID included in the extracted combination from the distance storage unit 310. Furthermore, the position estimation unit 320 performs three-point positioning based on the distance included in the extracted combination and the extracted position information. The result of the three-point positioning is the position of the tag 200 of the estimation target.

[0033] The subject of the device, system, or method in the present disclosure includes a computer. The computer executes a program to realize the function of the subject of the device, system, or method in the present disclosure. The computer includes a processor that operates according to a program as a main hardware configuration. The type of the processor does not matter as long as it can realize the function by executing the program. The processor is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). The multiple electronic circuits may be integrated into one chip or may be provided on multiple chips. The multiple chips may be integrated into one device or may be provided on multiple devices. The program is recorded on a non-transitory recording medium such as a computer-readable ROM, an optical disk, or a hard disk drive. The program may be stored in the recording medium in advance, or may be supplied to the recording medium via a wide area communication network including the Internet.

[0034] In this embodiment, a connection process and a disconnection process between the scanner 100 and the tag 200 are added to the wireless ranging system 1000 shown in FIG. 1 and FIG. 2(a)-(b). FIG. 4 is a sequence diagram showing a communication procedure by the wireless ranging system 1000. The tag 200 periodically broadcasts an advertisement (S10). When the scanner 100 receives the advertisement, the scanner 100 decides to measure the distance to the scanner 100 and transmits a connection request to the tag 200 (S12). In this manner, a connection process between the scanner 100 and the tag 200 is executed. The scanner 100 transmits a first measurement signal to the tag 200 (S14). The tag 200 transmits a reception result of the first measurement signal to the scanner 100 (S16). The tag 200 transmits a second measurement signal to the scanner 100 (S18). The scanner 100 measures the distance to the tag 200 based on the received second measurement signal and the reception result, and transmits a disconnection request to the tag 200 (S20). In this manner, the disconnection process between the scanner 100 and the tag 200 is executed.

[0035] 5(a)-(b) show another configuration of the tag 200 and the scanner 100 in the wireless ranging system 1000. FIG. 5(a) shows the configuration of the tag 200, in which a movement detection unit 270 is added to the configuration of FIG. 2(a). The tag 200 in FIG. 5(a) communicates with, for example, the scanner 100 in FIG. 2(a). The transmission unit 210 of the tag 200 periodically broadcasts an advertisement in response to an instruction from the control unit 260. The advertisement includes a tag ID.

[0036] The receiver 120 of the scanner 100 periodically receives an advertisement from the tag 200. Based on the advertisement received by the receiver 120, the control unit 160 determines to measure the distance to the tag 200 having the tag ID included in the advertisement. The control unit 160 instructs the transmitter 110 to execute a connection process with the tag 200. The transmitter 110 transmits a connection request in response to an instruction from the control unit 160. The connection request includes the scanner ID, and the destination of the connection request is set to the tag 200 having the tag ID.

[0037] The receiver 220 of the tag 200 receives a connection request from the scanner 100. The control unit 260 executes a connection process between the communication unit 202 and the scanner 100 based on the connection request received by the receiver 220. As a result of this process, the scanner 100 and the tag 200 are connected. When the scanner 100 and the tag 200 are connected, as described above, wireless communication is executed between the communication unit 102 and the communication unit 202, and the distance measurement unit 140 measures the distance between the scanner 100 and the tag 200.

[0038] Furthermore, the movement detection unit 270 of the tag 200 is a sensor for detecting the movement of the tag 200, and is, for example, an acceleration sensor. When the movement detection unit 270 detects movement, it notifies the transmission unit 210 of the detection of movement. When the movement detection unit 270 detects movement, the transmission unit 210 transmits movement information indicating the movement to the scanner 100. When the tag 200 transmits the movement information, the reception unit 120 of the scanner 100 receives the movement information. When the reception unit 120 receives the movement information, it outputs the movement information to the control unit 160.

[0039] When the first condition is satisfied after wireless communication between the communication unit 202 and the scanner 100, the control unit 160 decides to disconnect the tag 200 and the scanner 100. The first condition is that at least one state of the scanner 100 and the tag 200 satisfies the second condition after the distance measuring unit 140 completes measuring the distance between the tag 200 and the scanner 100, and the second condition is, for example, that the state of the tag 200 is in a moving state. The state of the tag 200 being in a moving state corresponds to the control unit 160 receiving moving information. In other words, the control unit 160 decides to disconnect the tag 200 when the distance measuring unit 140 completes measuring the distance and receives moving information from the tag 200. The control unit 160 instructs the transmission unit 110 to execute a disconnection process with the tag 200. The transmission unit 110 transmits a disconnection request in response to an instruction from the control unit 160.

[0040] The receiver 220 of the tag 200 receives a disconnection request from the scanner 100. The controller 260 executes a process of disconnecting the communication unit 202 from the scanner 100 based on the disconnection request received by the receiver 220. As a result of such a process, the connection between the scanner 100 and the tag 200 is disconnected. That is, the controller 260 releases the connection between the communication unit 202 and the scanner 100 when the third condition is satisfied after wireless communication between the communication unit 202 and the scanner 100 is performed. The third condition is that at least one state of the scanner 100 and the tag 200 satisfies the fourth condition after the scanner 100 completes the measurement of the distance between the scanner 100 and the tag 200, and the fourth condition is, for example, that the state of the tag 200 is a moving state. The third condition corresponds to the first condition, and the fourth condition corresponds to the second condition.

[0041] On the other hand, if the first condition or the second condition is not satisfied, the control unit 160 of the scanner 100 continues the connection between the tag 200 and the scanner 100. In this case, wireless communication is executed between the communication unit 102 and the communication unit 202, and the distance measurement unit 140 measures the distance between the scanner 100 and the tag 200. If the third condition or the fourth condition is not satisfied, the control unit 260 of the tag 200 continues the connection between the tag 200 and the scanner 100.

[0042] Movement of the tag 200 is detected by the movement detection unit 270, but is not limited to this. Fig. 5(b) shows the configuration of the scanner 100, in which a movement determination unit 170 is added to the configuration of Fig. 2(a). The scanner 100 of Fig. 5(b) communicates with, for example, the tag 200 of Fig. 2(a). The movement determination unit 170 observes the distance history of the tag 200, and detects the movement of the tag 200 when the change in the distance becomes larger than a threshold value. The control unit 160 determines that the second condition is satisfied when the movement of the tag 200 is detected by the movement determination unit 170.

[0043] Furthermore, the second and fourth conditions are not limited to the state of the tag 200 being in a moving state. The second and fourth conditions may be that the number of simultaneously connected devices between the scanner 100 and at least one of the tags 200 exceeds a threshold value. When the scanner 100 executes the above-mentioned connection process between the scanner 100 and multiple tags 200, the multiple tags 200 are connected simultaneously. The control unit 160 manages the number of connected tags 200. The control unit 160 compares the number of connected devices with a threshold value to determine the second condition.

[0044] The operation of the wireless ranging system 1000 configured as above will be described. Figures 6(a)-(b) are flowcharts showing the communication procedure by the scanner 100. In Figure 6(a), the communication unit 102 executes a connection process with the tag 200 (S100). The distance measurement unit 140 executes a distance measurement process with the tag 200 (S102). If the measurement is completed (Y in S104) and the tag 200 is in a moving state (Y in S106), the communication unit 102 executes a disconnection process with the tag 200 (S108). If the measurement is not completed (N in S104) or the tag 200 is not in a moving state (N in S106), the process returns to step 102.

[0045] 6(b), the communication unit 102 executes a connection process with the tag 200 (S150). The distance measurement unit 140 executes a distance measurement process with the tag 200 (S152). When the measurement is completed (Y in S154) and the number of new tags 200 connected after connection exceeds the threshold value (Y in S156), the communication unit 102 executes a disconnection process with the tag 200 (S158). When the measurement is not completed (N in S154) or when the number of new tags 200 connected after connection does not exceed the threshold value (N in S156), the process returns to step 152.

[0046] According to this embodiment, a disconnection process is performed after measuring the distance between the scanner 100 and the tag 200, so that a state in which the connection remains in progress can be avoided. In addition, since a state in which the connection remains in progress is avoided, an increase in traffic in wireless communication for measuring the distance between two wireless devices can be suppressed. In addition, since a disconnection is performed every time a distance is measured, management of the tag 200 in the scanner 100 can be simplified. In addition, since a connection process is performed between the scanner 100 and the tag 200, pre-registration of the tag 200 in the scanner 100 can be made unnecessary.

[0047] Furthermore, when the distance measurement is completed and the tag 200 is moving, the connection between the scanner 100 and the tag 200 is disconnected, so that the scanner 100 suitable for the moving tag 200 can measure the distance. Furthermore, when the tag 200 is not moving, the connection is maintained, so that an increase in traffic for the connection can be suppressed. Furthermore, suppressing the increase in traffic can reduce an increase in the number of tags that can be accommodated in the wireless ranging system 1000 or an impact on other wireless systems in the vicinity. Furthermore, when the number of tags 200 that are simultaneously connected to the scanner 100 exceeds a threshold value, the scanner 100 and the tag 200 are disconnected, so that an increase in the number of connected tags can be suppressed.

[0048] An overview of one aspect of the present disclosure is as follows. A first type radio device (100) of one aspect of the present disclosure is a first type radio device (100) including a communication unit (102) capable of performing wireless communication, a control unit (160) that executes a connection process between the communication unit (102) and a second type radio device (200), and a distance measurement unit (140) that measures the distance between the communication unit (102) and the second type radio device (200) through wireless communication between the communication unit (102) and the second type radio device (200) when the communication unit (102) is connected to the second type radio device (200) through the connection process by the control unit (160). After wireless communication between the communication unit (102) and the second type radio device (200) is performed, the control unit (160) releases the connection between the communication unit (102) and the second type radio device (200) when a first condition is satisfied.

[0049] The first condition may include that the distance measuring unit (140) has completed measuring the distance to the second type wireless device (200).

[0050] The first condition may include that at least one state of the first type radio device (100) and the second type radio device (200) satisfies the second condition after the distance measuring unit (140) completes measuring the distance between the first type radio device (100) and the second type radio device (200).

[0051] The second condition may include that the state of the second type wireless device (200) is a moving state.

[0052] The second condition may include that the number of simultaneously connected devices of at least one of the first type wireless devices (100) and the second type wireless devices (200) exceeds a threshold value.

[0053] The system may further include an external communication unit (150) that communicates with the external system (300). The first condition may include that the external communication unit (150) receives a connection release request from the external system (300).

[0054] Another aspect of the present disclosure is a second type wireless device (200). This device is a second type wireless device (200) capable of wireless communication with a first type wireless device (100), and includes a communication unit (202) capable of performing wireless communication, and a control unit (260) that performs connection processing between the communication unit (202) and the first type wireless device (100). When the communication unit (202) is connected to the first type radio device (100) through a connection process by the control unit (260), the communication unit (202) executes wireless communication between the communication unit (202) and the first type radio device (100) in order to cause the first type radio device (100) to measure the distance between the first type radio device (100) and the second type radio device (200), and when a third condition is satisfied after wireless communication between the communication unit (202) and the first type radio device (100) is established, the control unit (260) releases the connection between the communication unit (202) and the first type radio device (100).

[0055] The third condition may include that at least one state of the first type radio device (100) and the second type radio device (200) satisfies the fourth condition after the first type radio device (100) completes measuring the distance between the first type radio device (100) and the second type radio device (200).

[0056] The fourth condition may include that the state of the second type wireless device (200) is a moving state.

[0057] The fourth condition may include that the number of simultaneously connected devices of at least one of the first type wireless devices (100) and the second type wireless devices (200) exceeds a threshold value.

[0058] Yet another aspect of the present disclosure is a communication method in a first type wireless device (100) capable of wireless communication, comprising the steps of: executing a connection process between the first type wireless device (100) and a second type wireless device (200); when the first type wireless device (100) is connected to the second type wireless device (200) by the connection process, measuring the distance between the first type wireless device (100) and the second type wireless device (200) by wireless communication between the first type wireless device (100) and the second type wireless device (200); and, when a first condition is satisfied after wireless communication between the first type wireless device (100) and the second type wireless device (200), releasing the connection between the first type wireless device (100) and the second type wireless device (200).

[0059] Yet another aspect of the present disclosure is also a communication method. This method is a communication method in a second type radio device (200) capable of performing wireless communication with a first type radio device (100), and includes the steps of: executing a connection process between the second type radio device (200) and the first type radio device (100); when the second type radio device (200) is connected to the first type radio device (100) by the connection process, executing wireless communication between the second type radio device (200) and the first type radio device (100) to cause the first type radio device (100) to measure the distance between the first type radio device (100) and the second type radio device (200); and, after the wireless communication between the second type radio device (200) and the first type radio device (100) is performed, if a third condition is satisfied, releasing the connection between the second type radio device (200) and the first type radio device (100).

[0060] Example 2 Next, a second embodiment will be described. The second embodiment relates to a wireless ranging system 1000 similar to the first embodiment. As described above, the tag 200 periodically broadcasts advertisements. In the second embodiment, the advertisement transmission interval is adjusted to suppress an increase in traffic. The wireless ranging system 1000 according to the second embodiment is of the same type as that shown in FIG. 1. Here, the differences from the first embodiment will be mainly described.

[0061] 7(a)-(b) show the configurations of tag 200 and scanner 100. FIG. 7(a) shows the configuration of tag 200, where a movement detection unit 270 is added to the configuration of FIG. 2(a). Furthermore, tag 200 in FIG. 7(a) communicates with, for example, scanner 100 in FIG. 2(a). As described above, movement detection unit 270 is a sensor for detecting movement of tag 200. When movement detection unit 270 detects movement, it notifies control unit 260 of the detection of movement.

[0062] If the movement detection unit 270 does not detect movement, the control unit 260 determines the transmission interval of the advertisement to be a first value. The control unit 260 instructs the transmission unit 210 to periodically broadcast the advertisement with the transmission interval set to the first value. On the other hand, if the movement detection unit 270 detects movement, the control unit 260 determines the transmission interval of the advertisement to be a second value. The second value is a value smaller than the first value. The control unit 260 instructs the transmission unit 210 to periodically broadcast the advertisement with the transmission interval set to the second value.

[0063] Therefore, when the tag 200 is not moving, the advertisement transmission interval is made longer than when the tag 200 is moving, and the advertisement transmission frequency is made lower. As a result, an increase in traffic is suppressed.

[0064] FIG. 7(b) shows the configuration of the scanner 100, in which a period measurement unit 180 is added to the configuration of FIG. 2(a). Also, the scanner 100 of FIG. 7(b) communicates with, for example, the tag 200 of FIG. 2(a). The period measurement unit 180 measures the period after the distance measurement unit 140 measures the distance. The period is reset when the distance measurement unit 140 measures the distance. The control unit 160 determines the interval of advertisements periodically broadcast from the tag 200 based on the period measured by the period measurement unit 180. If the period does not exceed the threshold value, the control unit 160 determines the transmission interval of advertisements to be a first value. On the other hand, if the period exceeds the threshold value, the control unit 260 determines the transmission interval of advertisements to be a second value. The second value is a value smaller than the first value. The control unit 160 causes the transmission unit 110 to transmit the determined value of the transmission interval of advertisements to the tag 200.

[0065] When the receiver 220 receives the value of the advertisement transmission interval, the control unit 260 of the tag 200 controls the interval of the advertisements broadcast from the transmitter 210 based on the value of the advertisement transmission interval. That is, after the distance measurement is completed in the distance measuring unit 140 of the scanner 100, the transmitter 210 broadcasts the advertisements at an interval of a first value until the threshold value is reached. Also, when the threshold value is reached, the transmitter 210 broadcasts the advertisements at an interval of a second value. That is, the interval of the advertisement broadcast transmission is shortened as time passes.

[0066] The operation of the wireless ranging system 1000 configured as above will be described. Figures 8(a)-(b) are flowcharts showing the communication procedure by the scanner 100. In Figure 8(a), if the movement detection unit 270 does not detect the movement of the tag 200 (N in S200), the control unit 260 determines the advertisement transmission interval to be a first value (S202). If the movement detection unit 270 detects the movement of the tag 200 (Y in S200), the control unit 260 determines the advertisement transmission interval to be a second value (S204).

[0067] 8(b), if the threshold value or more has not elapsed since the previous distance measurement by the distance measurement unit 140 (N in S250), the control unit 160 determines the advertisement transmission interval to be a first value (S252). If the threshold value or more has elapsed since the previous distance measurement by the distance measurement unit 140 (Y in S250), the control unit 260 determines the advertisement transmission interval to be a second value (S254).

[0068] According to this embodiment, the advertisement transmission interval is controlled, so that an increase in traffic can be suppressed. Also, in the tag 200 that does not move much and therefore does not need to measure distance frequently, the advertisement transmission interval is extended, so that an increase in traffic can be suppressed. Also, in the tag 200 that does not need to measure distance because it has been a short period since measurement, the advertisement transmission interval is extended, so that an increase in traffic can be suppressed. Also, in the tag 200 that needs to measure distance because it has been a long period since measurement, the advertisement transmission interval is shortened, so that it is easy to measure distance.

[0069] An outline of one aspect of the present disclosure is as follows: The control unit (160) may determine the interval of the report signal periodically transmitted from the second type wireless device (200) according to the time since the distance measurement unit (140) measured the distance.

[0070] The present disclosure has been described above based on the embodiments. These embodiments are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0071] In the first embodiment, the first condition is that the measurement of the distance is completed and the second condition is satisfied. However, the present invention is not limited to this, and the first condition may be, for example, that the distance measuring unit 140 only completes the measurement of the distance to the tag 200. According to this modification, the processing can be simplified.

[0072] The first condition in the first embodiment may be that the external communication unit 150 receives a request for disconnection from an external system. The external system may be the position estimation device 300, or may be a device other than the position estimation device 300. According to this modification, a device other than the scanner 100 can instruct disconnection.

[0073] In the second embodiment, the transmission interval is defined in two stages, a first value and a second value. However, the present invention is not limited to this, and the transmission interval may be defined in three or more stages. According to this modification, the transmission interval can be set in detail. [Explanation of symbols]

[0074] 100 scanner (first type wireless device), 102 communication unit, 110 transmission unit, 120 reception unit, 130 derivation unit, 140 distance measurement unit, 150 external communication unit, 160 control unit, 170 movement determination unit, 180 period measurement unit, 200 tag (second type wireless device), 202 communication unit, 210 transmission unit, 220 reception unit, 230 derivation unit, 260 control unit, 270 movement detection unit, 300 position estimation device, 310 distance memory unit, 320 position estimation unit, 1000 wireless ranging system.

Claims

1. A first type wireless device, A communication unit capable of performing wireless communication; A control unit that executes a connection process between the communication unit and a second type wireless device; a distance measuring unit that measures a distance between the communication unit and the second type wireless device through wireless communication between the communication unit and the second type wireless device when the communication unit is connected to the second type wireless device through a connection process by the control unit, the control unit, when a first condition is satisfied after wireless communication between the communication unit and the second type wireless device is established, disconnects the communication unit from the second type wireless device; The distance measuring unit is a first type radio device that measures distance based on a reception result received from the second type radio device for a signal transmitted from the first type radio device to the second type radio device and a signal received from the second type radio device.

2. 2. The first type radio device according to claim 1, wherein the first condition includes that the distance measuring unit has completed measuring the distance to the second type radio device.

3. The first type radio device according to claim 1, wherein the first condition includes that at least one state of the first type radio device and the second type radio device satisfies a second condition after the distance measuring unit completes measuring the distance between the first type radio device and the second type radio device.

4. 4. The first type wireless device according to claim 3, wherein the second condition includes a state of the second type wireless device being a moving state.

5. 4. The first type wireless device according to claim 3, wherein the second condition includes a condition that the number of simultaneously connected devices of at least one of the first type wireless device and the second type wireless device exceeds a threshold value.

6. Further comprising an external communication unit for communicating with an external system; The first type wireless device according to claim 1 , wherein the first condition includes that the external communication unit receives a connection release request from the external system.

7. 2. The first type radio device according to claim 1, wherein the control unit determines an interval for the annunciation signal periodically transmitted from the second type radio device in accordance with a period of time since the distance measuring unit measured the distance.

8. A first type wireless device, A communication unit capable of performing wireless communication; A control unit that executes a connection process between the communication unit and a second type wireless device; a distance measuring unit that measures a distance between the communication unit and the second type wireless device through wireless communication between the communication unit and the second type wireless device when the communication unit is connected to the second type wireless device through a connection process by the control unit, the control unit, when a first condition is satisfied after wireless communication between the communication unit and the second type wireless device is established, disconnects the communication unit from the second type wireless device; The control unit determines an interval of a report signal periodically transmitted from the second type wireless device according to a period of time since the distance measuring unit measured the distance.

9. A second type wireless device capable of wirelessly communicating with a first type wireless device, A communication unit capable of performing wireless communication; a control unit that executes a connection process between the communication unit and the first type wireless device, when the communication unit is connected to a first type wireless device by a connection process performed by the control unit, the communication unit executes wireless communication between the communication unit and the first type wireless device to cause the first type wireless device to measure a distance between the first type wireless device and the second type wireless device; when a third condition is satisfied after wireless communication between the communication unit and the first type wireless device is established, the control unit releases the connection between the communication unit and the first type wireless device; The communication unit is a second type radio device that transmits a reception result of a signal from the first type radio device and a signal to the first type radio device in order to cause the first type radio device to measure the distance between the first type radio device and the second type radio device.

10. The second type radio device according to claim 9, wherein the third condition includes that at least one state of the first type radio device and the second type radio device satisfies a fourth condition after the first type radio device completes measuring the distance between the first type radio device and the second type radio device.

11. The second type wireless device according to claim 10 , wherein the fourth condition includes that the state of the second type wireless device is a moving state.

12. 11. The second type wireless device according to claim 10, wherein the fourth condition includes a condition that the number of simultaneously connected devices of at least one of the first type wireless device and the second type wireless device exceeds a threshold value.

13. A first type wireless device according to any one of claims 1 to 8, A second type wireless device according to any one of claims 9 to 12, A wireless ranging system comprising:

14. A communication method in a first type wireless device capable of performing wireless communication, comprising: executing a connection process between the first type wireless device and a second type wireless device; When the first type wireless device is connected to a second type wireless device by the connection process, measuring a distance between the first type wireless device and the second type wireless device through wireless communication between the first type wireless device and the second type wireless device; a step of releasing a connection between the first type wireless device and the second type wireless device when a first condition is satisfied after wireless communication between the first type wireless device and the second type wireless device is established; The measuring step is a communication method in which the distance is measured based on a reception result received from the second type radio device for a signal transmitted from the first type radio device to the second type radio device and a signal received from the second type radio device.

15. A communication method in a first type wireless device capable of performing wireless communication, comprising: executing a connection process between the first type wireless device and a second type wireless device; When the first type wireless device is connected to a second type wireless device by the connection process, measuring a distance between the first type wireless device and the second type wireless device through wireless communication between the first type wireless device and the second type wireless device; a step of releasing a connection between the first type wireless device and the second type wireless device when a first condition is satisfied after wireless communication between the first type wireless device and the second type wireless device is established; determining an interval for a report signal periodically transmitted from the second type wireless device in accordance with a period of time since a distance was measured; A communication method comprising:

16. A communication method in a second type wireless device capable of performing wireless communication with a first type wireless device, comprising: executing a connection process between the second type wireless device and the first type wireless device; When the second type wireless device is connected to the first type wireless device by the connection process, executing wireless communication between the second type wireless device and the first type wireless device to cause the first type wireless device to measure a distance between the first type wireless device and the second type wireless device; a step of releasing a connection between the second type wireless device and the first type wireless device when a third condition is satisfied after wireless communication between the second type wireless device and the first type wireless device is established; The step of performing wireless communication is a communication method in which a reception result of a signal from the first type radio device and a signal to the first type radio device are transmitted to the first type radio device so that the first type radio device measures the distance between the first type radio device and the second type radio device.

17. A program in a first type wireless device capable of performing wireless communication, executing a connection process between the first type wireless device and a second type wireless device; When the first type wireless device is connected to a second type wireless device by the connection process, measuring a distance between the first type wireless device and the second type wireless device through wireless communication between the first type wireless device and the second type wireless device; a step of releasing a connection between the first type wireless device and the second type wireless device when a first condition is satisfied after wireless communication between the first type wireless device and the second type wireless device is established; The measuring step is a program for causing a computer to execute the following: measuring the distance based on a reception result received from the second type radio device regarding the signal transmitted from the first type radio device to the second type radio device, and based on the signal received from the second type radio device.

18. A program in a first type wireless device capable of performing wireless communication, executing a connection process between the first type wireless device and a second type wireless device; When the first type wireless device is connected to a second type wireless device by the connection process, measuring a distance between the first type wireless device and the second type wireless device through wireless communication between the first type wireless device and the second type wireless device; a step of releasing a connection between the first type wireless device and the second type wireless device when a first condition is satisfied after wireless communication between the first type wireless device and the second type wireless device is established; and a step of determining an interval for a notification signal periodically transmitted from the second type wireless device in accordance with a period of time since the distance was measured.

19. A program in a second type wireless device capable of wireless communication with a first type wireless device, executing a connection process between the second type wireless device and the first type wireless device; When the second type wireless device is connected to the first type wireless device by the connection process, executing wireless communication between the second type wireless device and the first type wireless device to cause the first type wireless device to measure a distance between the first type wireless device and the second type wireless device; a step of releasing a connection between the second type wireless device and the first type wireless device when a third condition is satisfied after wireless communication between the second type wireless device and the first type wireless device is established; The step of performing wireless communication includes a program for causing a computer to execute the steps of: transmitting a reception result of a signal from the first type radio device and a signal to the first type radio device in order to have the first type radio device measure the distance between the first type radio device and the second type radio device.

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