Position determination method and system

Abstract

A data management system 303 according to the present disclosure is characterized by comprising: a movable beacon device 17 that is movable; and a management node 13 that acquires information pertaining to a received signal strength obtained at the time when a signal transmitted from the movable beacon device 17 has been received by a terminal 21 and that calculates the position of the terminal 21 on the basis of a change between received signal strengths which have been obtained before and after movement of the movable beacon device 17.

Description

Position determination method and system

[0001] The present disclosure relates to calculating location in the Internet of Things (IoT).

[0002] It has been known that network configuration information and device information of terminals and devices can be acquired using a standardized, lightweight communication protocol that does not require high performance. For example, Non-Patent Document 1 discloses a data acquisition method that uses an extension area of ​​LLDP (Link Layer Discovery Protocol; see Non-Patent Document 3).

[0003] In the IoT, it is known that multiple (large numbers of) sensor terminals are connected to a network and the data (sensing data) generated by them is collected and utilized. Furthermore, in data utilization in the IoT, it has been reported that not only the sensing data itself generated by the sensor terminals but also data related to the sensing data, known as metadata, is important (see Non-Patent Document 2). By acquiring and distributing the metadata together with the sensing data, it is expected that users will be able to utilize the sensing data safely and easily. For example, by utilizing the extended area of ​​LLDP disclosed in Non-Patent Document 1 to exchange metadata, it is possible to collect metadata (device information) related to the sensing data, such as manufacturer name and model number, with an economical system configuration.

[0004] As an example of how metadata can be used, the position of an IoT device can be calculated using a plurality (a large number) of beacon signal transmitting devices for position calculation that are fixed in advance at predetermined positions.

[0005] Yoshiyuki Mihara, Takefumi Yamazaki, Manabu Okamoto, and Atsushi Sato, "Design of Home Network Mapping Protocol HTIP and Its Application to Diagnostic Tools," Transactions of the Information Processing Society of Japan, Consumer Devices & Systems, Vol. 2, No. 3, pp. 34-45, December 2012. Toshihiko Oda, Hiroshi Imai, Takeshi Naito, and Hajime Takebayashi, "A Method for Defining, Generating, and Utilizing Metadata in the Sensing Data Distribution Market," Proceedings of the 32nd Annual Conference of the Japanese Society for Artificial Intelligence, June 2012. IEEE Std 802.1AB-2016, “IEEE Standard for Local and metropolitan area networks-Station and Media Access Control “Connectivity Discovery” IEEE Std 802.11TM-2016 P. 708 (Probe Request), P.708 (Probe Request). 712 (Probe Response)

[0006] However, in the above-mentioned position calculation method, the position of the beacon signal transmitting device is fixed, and a large number of beacon signal transmitting devices (at least three) are required. Therefore, manufacturing and maintenance of the beacon signal transmitting devices are costly, and therefore, it is desirable to calculate the position of IoT devices with a more economical system configuration.

[0007] Therefore, in order to solve the above problem, an object of the present disclosure is to provide a data management system that is capable of calculating the position of an IoT device with a simple system configuration.

[0008] In order to solve the above problems, the data management system of the present disclosure adopts a method of moving a beacon signal sending device or other communication device relative to an IoT device and calculating the position of the IoT device based on changes in the beacon signals and other signals sent and received by the IoT device.

[0009] Specifically, the system of the present disclosure is characterized by comprising: a first communication unit and a second communication unit, at least one of which is movable; and a calculation unit that acquires reception information when a signal transmitted from the first communication unit is received by the second communication unit, and calculates the position of the first communication unit or the second communication unit based on changes in the reception information obtained before and after movement of either the first communication unit or the second communication unit.

[0010] Furthermore, the position determination method of the present disclosure is a position determination method executed by a system having a first communication unit and a second communication unit, at least one of which is movable, and is characterized by including the steps of: acquiring reception information when a signal transmitted from the first communication unit is received by the second communication unit; and calculating the position of the first communication unit or the second communication unit based on changes in the reception information obtained before and after movement of either the first communication unit or the second communication unit.

[0011] According to such a system configuration or method, by moving either the first communication unit or the second communication unit, the position of the first communication unit or the second communication unit can be calculated with a simple configuration based on changes in the received information received by the second communication unit.

[0012] It is preferable that the second communication unit stores the received information as metadata in an extension area within a control frame defined by a standardized wireless communication protocol, and transmits the metadata stored in the extension area to the calculation unit.

[0013] With this configuration, it is possible to acquire network configuration information, device information, sensor data, and metadata of a terminal or device using a communication protocol that does not require high performance, and it is also possible to calculate the position of the first communication unit or the second communication unit with an economical system configuration.

[0014] It is preferable that the calculation unit calculates the position of the first communication unit or the second communication unit based on the distance obtained from the received information before the movement and the distance obtained from the received information after the movement.

[0015] With this configuration, the position of the first communication unit or the second communication unit can be preferably calculated based on the change in distance obtained from the received information before and after movement of either the first communication unit or the second communication unit.

[0016] The above disclosures can be combined as much as possible.

[0017] According to the present disclosure, it is possible to grasp a change in the relative position of a second transmission unit with respect to a first transmission unit based on a change in a signal between a first communication unit and a second communication unit that move relative to each other and transmit and receive signals. For example, it is possible to grasp a change in the relative position of a beacon transmission device that moves relative to an IoT device. This makes it possible to calculate the position of an IoT device with a simple system configuration.

[0018] 1 is a diagram illustrating a network configuration of a data management system according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating a configuration of a terminal of a data management system according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a configuration of a manager node of a data management system according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating a frame transmitted from a terminal to a manager node. FIG. 4 is a diagram illustrating an overview of a data management system according to an embodiment of the present disclosure. FIG. 5 is a block diagram illustrating a system configuration of a data management system according to an embodiment of the present disclosure. FIG. 6 is a sequence diagram illustrating transmission and reception of signals and data in a data management system according to an embodiment of the present disclosure. FIG. 7 is a diagram illustrating a method for searching for associated terminals. FIG. 8 is a diagram illustrating a method for searching for terminals according to an embodiment. FIG. 9 is a diagram illustrating a method for searching for associated terminals. FIG. 10 is a diagram illustrating a method for searching for terminals according to an embodiment. FIG. 11 is a diagram illustrating a triangulation method. FIG. 12 is a diagram illustrating an overview of a data management system according to an embodiment of the present disclosure. FIG. 13 is a block diagram illustrating a system configuration of a data management system according to an embodiment of the present disclosure. FIG. 14 is a sequence diagram illustrating transmission and reception of signals and data in a data management system according to an embodiment of the present disclosure. FIG. 15 is a diagram illustrating a triangulation method. FIG. 16 is a diagram illustrating an overview of a data management system according to a modified example of an embodiment of the present disclosure. FIG. 17 is a sequence diagram illustrating transmission and reception of signals and data in a data management system according to a modified example of an embodiment of the present disclosure. FIG. 10 is a sequence diagram illustrating transmission and reception of signals and data in a data management system according to a modified example of an embodiment of the present invention.

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0020] (Embodiment 1) A data management system according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 4. In this embodiment, the basic configuration of the data management system will be described. FIG. 1 is a diagram illustrating a data management system 301 according to this embodiment. The data management system 301 is a data management system that performs communication from a terminal 11 to a network device 12 by utilizing an extended area of ​​a standardized communication protocol (such as LLDP, HTIP, or IEEE 802.11). The terminal 11 stores sensing data detected by a sensor device in an area within a frame defined by the communication protocol that is different from an area for storing metadata, and transmits the data to the network device 12. The network device 12 forwards the frame to a management node 13. The management node 13 associates the sensing data with the metadata and stores them based on information identifying the terminal 11 that is written in the frame.

[0021] The data collection network 15 is a network that connects the terminals 11 that exist within a specific range to the management node 13. The data collection network 15 is, for example, a local area network (LAN), a field area network (FAN), an IoT area network, etc. There are cases where multiple terminals 11 of the same type exist within the same data collection network 15, and cases where multiple types of terminals 11 exist within the same data collection network 15.

[0022] 2 is a diagram illustrating the terminal 11. The terminal 11 is, for example, an IoT sensor terminal that senses an observation target and generates sensing data. The terminal 11 includes a sensor device 11a, a sensing data storage processing unit 11b, a device information storage processing unit 11c, a communication protocol operation unit 11d1, metadata detection units (metadata 1 detection unit 11e1, metadata 2 detection unit 11e2, metadata 3 detection unit 11e3, ...), and a metadata storage processing unit 11f.

[0023] The sensor device 11a senses the observation target and acquires sensing data (main data). The sensing data may be, for example, temperature, images, acceleration, sound, light, CO2, etc. The device information storage processing unit 11c collects device information about the observation target (for example, the device manufacturer name, model name, model number, etc.) and stores the information in a predetermined position in the frame (an area that can be used for unique purposes, such as an "extension area" or "optional area" specified by the protocol).

[0024] The sensing data storage processing unit 11b stores the sensing data from the sensor device 11a in a predetermined position of the frame (such as the payload portion defined by the protocol). The sensing data storage processing unit 11b may process the sensing data and store it in the frame, for example, by converting it into a short code or by dividing it into multiple frames and storing it (fragmentation), so that the data conforms to the format / restrictions of the unique extension area of ​​the frame.

[0025] The sensing data storage processing unit 11b can arbitrarily set the timing for storing the sensing data in the frame. For example, the storage timing can be set each time the sensing data is updated, or the sensing data can be stored not sequentially but after it has been accumulated for a certain period of time. Furthermore, when the sensing data has been accumulated for a certain period of time, the sensing data storage processing unit 11b can store a record (log) of the sensing data or the results of specific calculations / statistical processing in the frame.

[0026] The type of sensing data stored in the frame and the storage timing may be fixed or variable. The type of sensing data and the storage timing may be dynamically changed based on the judgment of the terminal 11 itself or an instruction from the management node 13 or the network device 12. The frame transmission cycle may also be fixed or variable. The frame transmission cycle may be dynamically changed based on the judgment of the terminal 11 itself or an instruction from the management node 13 or the network device 12.

[0027] The metadata detection unit 11e acquires information (metadata) other than device information. Examples of information other than device information include location information of the detection target, time information, information about people, objects, or events, and other information. However, the present invention does not limit the information other than device information to these. To acquire this information, the metadata detection unit 11e includes a metadata 1 detection unit 11e1, a metadata 2 detection unit 11e2, a person, object, or metadata 3 detection unit 11e3, and other detection units.

[0028] The metadata 1 detection unit 11e1 is, for example, a GPS, an acceleration sensor, a gyro sensor, or an RSSI (Received Signal Strength Indicator) receiver for Wi-Fi signals, BLE beacon signals, etc. The location metadata detected by the metadata 1 detection unit 11e1 is information about geographical locations acquired from GPS signals, BLE beacon signals, radio wave information for wireless communication, radio wave information for non-communication (television, radio, radio clocks, other noise, etc.), power information, visible light information, sound wave information, vibration information, acceleration information, and other location metadata sources.

[0029] The metadata 2 detection unit 11e2 is, for example, an information receiver from GPS or NTP (Network Time Protocol). The time metadata detected by the metadata 2 detection unit 11e2 is information about time acquired from a GPS signal, information from the NTP, or other time metadata sources.

[0030] The person, object, and metadata 3 detection unit 11e3 is a receiver that receives, for example, information from a BLE beacon (carried by the person), a smartphone carried by the person, or information from image analysis results. The person, object, or event metadata detected by the person, object, and metadata 3 detection unit 11e3 is information about people, objects, or events obtained from a BLE beacon carried by the person, information from a smartphone carried by the person, information from image analysis results, or other current event metadata sources.

[0031] Other metadata detected by the detection unit includes information about the network configuration, etc. The metadata detection unit 11e may detect all of the multiple detection targets, or may detect any one of them.

[0032] The metadata storage processing unit 11f stores the data detected by the metadata detection unit 11e as metadata in an extension area or an optional area within the frame set by the communication protocol. For example, the metadata storage processing unit 11f can store metadata in a control frame of an IEEE 804.11 wireless LAN. Specifically, the metadata storage processing unit 11f stores various metadata in a "Vendor Specific" area, which is an extension area of ​​a Probe Request frame. Alternatively, the metadata storage processing unit 11f stores various metadata in a "Vendor Specific" area, which is an extension area of ​​a Probe Response frame.

[0033] The metadata storage processing unit 11f may process the metadata and then store it in the frame, such as by converting it into a shortened code and storing it, or by dividing it and storing it in multiple frames (fragmentation), so that it conforms to the format / restrictions of the frame's unique extension area.

[0034] The metadata storage processing unit 11f can arbitrarily set the timing for storing metadata in a frame. For example, the storage timing can be set each time the metadata is updated, or the metadata can be stored after it has been accumulated for a certain period of time rather than sequentially. Furthermore, when the metadata storage processing unit 11f has accumulated metadata for a certain period of time, it can store a record (log) of the metadata or the results of specific calculations or statistical processing in the frame.

[0035] The type of metadata stored in a frame and the timing of storage may be fixed or variable. The type of metadata and the timing of storage may be dynamically changed at the discretion of the terminal 11 itself or in response to an instruction from the management node 13.

[0036] The communication protocol operation unit 11d1 transmits a frame, in which sensing data and device information are stored in a predetermined area and metadata is stored in an extended area or an optional area, to the network device 12 using a lightweight, standardized communication protocol such as LLDP or HTIP. Note that the communication protocol of the frame in which sensing data is stored and the communication protocol of the frame in which device information is stored may be the same or different. In the latter case, the metadata storage processing unit 11f may store the metadata in a frame of one of the communication protocols (a frame in which sensing data is stored or a frame in which device information is stored) or in frames of both communication protocols (a frame in which sensing data is stored and a frame in which device information is stored).

[0037] Furthermore, the terminal 11 also has a function of operating in accordance with instructions from a management node or the like. Specifically, the terminal 11 has an instruction interpretation unit 11g, and when changing the BLE beacon signal or metadata information (information to be transmitted, radio wave intensity, transmission frequency, etc.) transmitted by the terminal itself in accordance with instructions from the management node 13, the terminal 11 transmits the information to the outside. When transmitting information using the same protocol as communication with the network device 12, the terminal 11 operates a communication protocol operation unit 11d1. When transmitting information using a protocol different from communication with the network device 12, the terminal 11 has a communication protocol operation unit 11d2 in addition to the communication protocol operation unit 11d1, and operates the communication protocol operation unit 11d2.

[0038] The terminal 11 may also be a beacon signal source for other terminals to grasp metadata. For example, the terminal 11 may be a beacon signal source for identifying location metadata, or may be a beacon terminal carried by a worker to identify nearby people.

[0039] The network device 12 is, for example, a network switch, a wireless access point, a wireless repeater, or the like. The network device 12 transmits frames uploaded from the lower-level data collection network 15 to the management node 13 as they are. Here, the network device 12 may have a metadata processing unit (metadata detection unit 11e and metadata storage processing unit 11f) that the terminal 11 has. Even if the network device 12 does not have the sensor device 11a, it can add metadata such as its own unique information, such as its MAC address, and connection port information to frames sent from the terminal 11 and forward them to the management node 13. If the network device 12 has a metadata processing unit, it can grasp the logical connection from the management node 13 to the terminal 11, allowing for the creation of a more accurate logical / physical network management map. In other words, even if the network device 12 is a network switch (switching hub) or a wireless repeater that does not have layer 3 or higher functionality, the present technology operates at layer 2, making it possible to manage and grasp the connections between network devices, including the network device 12.

[0040] The communication protocol operation unit 13a receives frames containing sensing data and metadata from the terminal 11 or the network device 12. The information processing unit 12b extracts the following sensing data, device information, and metadata from the received frames and organizes them in the information storage unit 13c based on the unique information of the terminal 11: (1) physical information of the terminal (information such as the housing features, image information, information on attached labels, the object the worker is pointing at, the object the worker is looking at, etc.), (2) identifiers of terminals on the logical network (MAC address, UUID (Universally Unique Identifier), etc.), (3) primary data (sensing data such as temperature, image, acceleration, sound, light, CO2, etc.), and (4) various metadata (data on location, time, people, objects, events, etc.). For example, the management node 13 references metadata related to a location and stores primary data acquired at the same location or within a certain area in the format of [location metadata, primary data].

[0041] A supplementary note on location metadata: Information or signals received by the terminal 11, such as GPS signals, may be directly location metadata at the time of sensing by the terminal 11. On the other hand, signals such as signals from BLE beacons, visible light, or sound information may not be determined to be location information at the time of sensing by the terminal 11 and transmitting as metadata, and the management node 13 may recognize / understand the metadata as location metadata.

[0042] FIG. 4 is a diagram illustrating a frame 41 transmitted from the terminal 11 to the management node 13. The network device 12 is not shown in FIG. 4 . The frame 41 is a Layer 2 communication frame set by a communication protocol such as an Ethernet (registered trademark) frame or a Wi-Fi communication frame. The frame 41 is composed of a logical identifier 41a of the communication device such as a MAC address, a source and destination identifier 41b such as an IP address, an area 41c in which sensing data such as temperature and image is stored, and an extension area 41d in which metadata is stored. Of these, the identifier 41b and area 41c form a Layer 3 communication packet. IEEE 804.11 wireless LAN control system frames such as a probe request and a probe response also have a similar configuration to the frame 41.

[0043] The management node 13, for example, combines the MAC address of the logical identifier 41a with the location metadata of the extension area 41d to form [MAC address, location metadata], and combines the MAC address of the logical identifier 41a with the installer metadata of the extension area 41d to form [MAC address, installer metadata], and organizes them in the information storage unit 13c.

[0044] In this way, the data management system 301 can acquire network configuration information, device information, sensor data, and metadata of terminals and devices using a communication protocol that does not require high performance.

[0045] (Embodiment 2) A data management system according to an embodiment of the present disclosure will be described with reference to Figures 5 to 9. The metadata detection unit 11e provided in the terminal 11 can function as a beacon signal receiving unit that receives signals from various metadata sources. Furthermore, the metadata 1 detection unit 11e1 that receives the beacon signal can function as a beacon signal transmitting unit that transmits the beacon signal. Therefore, in this embodiment, the terminal 11 is provided with a beacon signal transmitting and receiving function, and the location of the terminal 11 is determined using information obtained by transmitting and receiving signals between terminals 11.

[0046] 5 is a diagram illustrating an overview of the data management system 302. The data management system 302 includes terminals 21, 14-1, 14-2, and 14-3 as terminals 11. In this embodiment, the metadata 1 detection unit 11e1 included in each of the terminals 14-1, 14-2, and 14-3 has a function of transmitting a beacon signal. The metadata 1 detection unit 11e1 included in the terminal 21 receives the beacon signal. The terminal 21 transmits the received beacon signal as metadata via a low-layer (layer 2) communication function. The management node 13 calculates the position of the terminal 21 based on the received metadata.

[0047] In this embodiment, a case where four terminals are used will be described, but the number of terminals included in the data management system 302 according to this embodiment is not limited to three. Each of the terminals 21, 14-1, 14-2, and 14-3 may be the terminal 21 equipped with the sensor device 11a described in FIG. 2, or a location-finding terminal such as a BLE beacon that serves as a location metadata source. Each of the terminals 11, 14-1, 14-2, and 14-3 may be an installed type that has a fixed position, a portable type that can freely change its position as described below, or a patrol robot type that periodically circulates. Additionally, each of the terminals 21, 14-1, 14-2, and 14-3 may be a terminal that can collect various secondary sensor data that can be used as metadata.

[0048] Based on instructions from the management node 13, each of the terminals 14-1, 14-2, and 14-3 transmits a beacon signal at a predetermined transmission signal strength X to the terminal 21, the position of which is to be calculated, at an arbitrary timing (steps S1-1, 1-2, and 1-3). The beacon signal includes information unique to each of the terminals 14-1, 14-2, and 14-3 and information on the transmission signal strength X (hereinafter referred to as transmission signal strength information). Here, an example is shown in which the transmission signal strength X from the terminals 14-1, 14-2, and 14-3 is a common transmission signal strength of 10. Note that, in this embodiment, the combination of the strengths of the beacon signals transmitted by the terminals 14-1, 14-2, and 14-3 is not limited to this, and each terminal may transmit a beacon signal with a different transmission signal strength. The metadata 1 detection unit 11e1 of the terminal 21 receives the beacon signal. The metadata 1 detection unit 11e1 receives the beacon signal and measures its received signal strength. As a result, the metadata 1 detection unit 11e1 of the terminal 21 can acquire the unique information of the sender of the beacon signal, the transmitted signal strength information, and the received signal strength.

[0049] The terminal 21 stores reception information of the beacon signals received from each of the terminals 14-1, 14-2, and 14-3 as metadata in an extension field of the Probe Request. Here, the "reception information" stored as metadata includes unique information of the sender of the beacon signal, transmitted signal strength information, and received signal strength. The "reception information" may include the time when the beacon signal was transmitted from the terminals 14-1, 14-2, and 14-3, and the time when the beacon signal was received by the terminal 21. The "reception information" may also include information regarding the geographical location of the sender of the beacon signal (in this embodiment, the terminals 14-1, 14-2, and 14-3).

[0050] 4, the Probe Request stores a logical identifier 41a such as the MAC address of the terminal 21. Therefore, the management node 13 collects the reception information and logical identifiers of the terminal 21 all at once. Furthermore, it becomes possible to easily distinguish and manage and visualize the terminals 14-1, 14-2, and 14-3.

[0051] 6 is a block diagram illustrating the system configuration of the data management system 302. The data management system 302 includes the above-mentioned terminal 21, management node 13, terminals 14-1, 14-2, and 14-3, as well as a network device 12. In this example, each of the terminals 14-1, 14-2, and 14-3 includes a beacon signal transmitter 14a, and the network device 12 includes a communication protocol receiver 12a.

[0052] Each of the terminals 14-1, 14-2, and 14-3 includes a beacon signal transmitting unit 14a, which is configured to periodically transmit a beacon signal to the outside (S1-1, S1-2, and S1-3).

[0053] The terminal 21 includes a beacon signal receiving unit 21a and a communication protocol operation unit 21b. The beacon signal receiving unit 21a receives beacon signals transmitted from the terminals 14-1, 14-2, and 14-3. The beacon signal receiving unit 21a stores the received information as metadata in an extension area of ​​the Probe Request frame.

[0054] The communication protocol operation unit 21b transmits the Probe Request frame generated by the beacon signal reception unit 21a (S2). As a result, reception information of the beacon signal received by the terminal 21 is broadcast. The communication protocol reception unit 12a of the network device 12 receives the frame group transmitted by the communication protocol operation unit 21b and reads the metadata from the extension area. The communication protocol reception unit 12a sends the read metadata to the management node 13 (S3).

[0055] As in the first embodiment, the management node 13 includes a communication protocol operation unit 13a, an information processing unit 13b, and an information storage unit 13c. The communication protocol operation unit 13a receives frames containing sensing data and metadata from the terminal 21 and the network device 12. The information processing unit 13b processes the sensing data and metadata as appropriate. The data processed by the information processing unit 13b is stored retrievably in the information storage unit 13c.

[0056] The operation of the data management system 302 will be described in detail with reference to Fig. 7. Fig. 7 is a sequence diagram illustrating the transmission and reception of signals and data in the data management system 302.

[0057] Based on instructions from the management node 13, each of the terminals 14-1, 14-2, and 14-3 transmits a beacon signal with a predetermined transmission signal strength X to the terminal 21 whose position is to be calculated at any timing (steps S1-1, S1-2, and S1-3).

[0058] The terminal 21 stores the reception information of the beacon signals received from the terminals 14-1, 14-2, and 14-3 as metadata in the extension area of ​​the probe request, and transmits it to the network device 12 (steps S2-1, S2-2, and S2-3).

[0059] The network device 12 reads the metadata in the extension area from the Probe Request frame sent from the terminal 21 (S3-1, S3-2, and S3-3). The network device 12 sends the read metadata to the management node 13. The metadata sent to the management node 13 is stored in the information storage unit 13c of the management node 13 and is used when calculating the position of the terminal 21, etc. (S4-1, S4-2, and S4-3).

[0060] The reception strength at terminal 21 of the beacon signals transmitted from each of terminals 14-1, 14-2, and 14-3 varies depending on the relative distance between each of terminals 14-1, 14-2, and 14-3 and terminal 21. Here, the reception strength at terminal 21 of the beacon signal transmitted from terminal 14-1 is set to 8, the reception strength at terminal 21 of the beacon signal transmitted from terminal 14-2 is set to 6, and the reception strength at terminal 21 of the beacon signal transmitted from terminal 14-3 is set to 4. In this way, the metadata includes transmitted signal strength information of the beacon signals and received signal strength information of the beacon signals at terminal 21. Therefore, the straight-line distance between terminal 21 and each of terminals 14-1, 14-2, and 14-3 can be calculated from the difference between the transmitted signal strength and the received signal strength.

[0061] Here, it can be said that the greater the difference between the transmitted signal strength and the received signal strength of the beacon signal between the terminals, the greater the distance between the terminals. In the example of this embodiment, the difference between the transmitted signal strength and the received signal strength of the beacon signal between terminal 14-1 and terminal 21 is "2." The difference between the transmitted signal strength and the received signal strength of the beacon signal between terminal 14-2 and terminal 21 is "4." The difference between the transmitted signal strength and the received signal strength of the beacon signal between terminal 14-3 and terminal 21 is "6." Therefore, it can be said that the distance between terminal 14-1 and terminal 21 is the shortest, and the distance between terminal 14-3 and terminal 21 is the longest.

[0062] The above description has been given of a case where beacon signals are transmitted from the terminals 14-1, 14-2, and 14-3 and received by the terminal 21. However, the scope of the present disclosure is not limited to this, and the terminal 21 may be configured to transmit a beacon signal, and the terminals 14-1, 14-2, and 14-3 may receive the beacon signal transmitted from the terminal 21.

[0063] Next, a method for searching for IoT devices using beacon signals will be described. Fig. 8 is a diagram illustrating a method for searching for terminal 21 using terminal 14. As described above, in this embodiment, the straight-line distance between terminal 21 and each of terminals 14-1, 14-2, and 14-3 can be calculated from the difference between the transmitted signal strength and the received signal strength.

[0064] Conventionally, there has been a problem in that the location of IoT devices installed outdoors, such as in forests or farms, or in large indoor spaces, such as in factories or warehouses, can become unknown. For example, in a forest as shown in Fig. 8A, even if an existing terminal 21A is installed, it may not be possible to find it.

[0065] In contrast, in this embodiment, the position of the terminal 21 can be searched for by calculating the straight-line distance between the terminal 21 and the terminal 14 from the difference between the transmitted signal strength and the received signal strength, as described above. Therefore, as shown in FIG. 8B , the position of the terminal 21 calculated by the management node 13 is displayed on the terminal 14, allowing the worker to search for the position of the terminal 21. Here, in this embodiment, a Probe Request, which is a low-layer (layer 2) communication, is used to transmit metadata from the terminal 21, so the management node 13 can calculate the position of the terminal 21 almost in real time. Therefore, it is possible to search for the position of the terminal 21 using a beacon signal from the terminal 14, like sonar.

[0066] [Comparison with Existing Technology] Next, a comparison will be made between a method for searching for terminal 21 using terminal 14 and a method for searching for terminal 21A according to existing technology. Fig. 9 is a diagram illustrating a comparison between a method for searching for terminal 21 using terminal 14 and a method for searching for existing terminal 21A according to a conventional configuration. Fig. 9A shows a method for searching for the location of existing terminal 21A using switch terminal 14A. Fig. 9B shows a method for searching for the location of terminal 21 according to this embodiment using terminal 14 according to this embodiment.

[0067] 9A , in the existing technology, when an operator operates (presses a switch on) switch terminal 14A near the target terminal, a signal is transmitted to nearby existing terminal 21A via Bluetooth (registered trademark) communication, etc. Upon receiving the signal from switch terminal 14A, existing terminal 21A emits sound, LED light, etc. to notify the operator of the location of existing terminal 21A.

[0068] However, the existing technology has the following problems. (1) When the existing terminal 21A is located in a mountain forest or the like, the visible light and sound from the existing terminal 21A may be blocked by an obstacle before the worker can recognize it, making it difficult to locate the position of the existing terminal 21A. (2) There are cases where visible light and sound cannot be used to locate the position of the existing terminal 21A. For example, visible light cannot be used in a warehouse that is required to be a dark room. Also, for example, in quiet environments, it is conceivable that emitting sound is prohibited. (3) When visible light and sound are used, it may be difficult to identify the position of the existing terminal 21A because human recognition is used as the basis.

[0069] 9B, in this embodiment, the terminal 14 periodically transmits a beacon signal, and the terminal 21 broadcasts the received information as metadata. The method of this embodiment provides the following advantages: (1) The location of the terminal 21 can be displayed on the terminal 14, making it possible to accurately identify the location of the terminal 21. (2) Because the beacon signal contains information specific to the terminal 14, the management node 13 can identify the three-dimensional location of the terminal 21 using a method such as triangulation, provided that it can use beacon signals from the different terminals 14-1, 14-2, and 14-3.

[0070] [Relative Position Calculation Method] The following describes the method used by the management node 13 to calculate the relative position of the terminal 21. (Step 1) Calculate the distance between two terminals from the received signal strength Y and the transmitted signal strength X. The received signal strength Y is, for example, an RSSI value, and is generated as a numerical value by the terminal 21 when it receives a signal. The formula for calculating the distance d between two terminals is as follows: d = 10 ((X - Y) / N x 10) Here, N is a coefficient that changes depending on the environment of the space in which the beacon is placed. In an ideal space with no obstacles, N = 2.0, In a space where radio waves propagate while being reflected, N < 2.0, In a space where radio waves propagate while being absorbed by obstacles and attenuated, N > 2.0.

[0071] [Specific Measurement Method] The terminal 14 emits a sweeping beacon signal so that the transmission strength changes from a weak state to a strong state, and the terminal 14 and nearby terminals mutually collect RSSI (Received Signal Strength Indicator). By performing such a sweeping emission, more information is available for reference, making it easier to calculate the distance d between the terminals and the coefficient N.

[0072] In order to measure the distance between terminals using beacon signals, it is preferable that the beacon signals contain a signal strength reference value. Although distance measurement is possible using RSSI alone, the measurement results at the management node 13 become accurate by determining whether the RSSI is greater or less than the signal strength reference value at the management node 13. By comparing these two values, it becomes possible to determine that if the RSSI is greater than the reference value, the distance is within one meter; if not, the distance is greater than that.

[0073] Here, the signal strength reference value can be predetermined, for example, the RSSI value when received at a position one meter away from the transmitting device. If the device can transmit a beacon signal in the iBeacon (registered trademark) or AltBeacon format, the signal strength reference value can be attached to the end of the beacon information and transmitted.

[0074] (Procedure 2) The management node 13 acquires the inter-terminal distances d between multiple terminals in procedure 1 and calculates the approximate relative positions in two-dimensional / three-dimensional space. The calculation method can use estimation techniques such as fingerprinting, triangulation, and weighted centroid (WCL) methods. Procedure 2 can use any one or a combination of these techniques.

[0075] (1) Triangle Positioning Method FIG. 10 is a diagram illustrating the triangle positioning method. As in step 1, the distances (d1, d2, d3) between three or more terminals (for example, terminals 14-1, 14-2, 14-3) and terminal 21 are obtained, and a point is derived where the circumferences of the distances d1, d2, d3 centered at each of terminals 14-1, 14-2, 14-3 intersect. This point is calculated as the position of terminal 21. In this embodiment, the positions of terminals 14-1, 14-2, 14-3 are managed by management node 13. Therefore, management node 13 can calculate the position of terminal 21 using the positions of terminals 14-1, 14-2, 14-3 and the inter-terminal distances d from terminals 14-1, 14-2, 14-3.

[0076] (2) WCL Method Figure 9 is also a diagram explaining the WCL method. As in step 1, the distances (d1, d2, d3) between three or more terminals (e.g., terminals 14-1, 14-2, 14-3) and terminal 21 are obtained. "Weights" are calculated from these distances, and the position of terminal 21 is calculated from the balance between the "weights." Compared to the triangular positioning method, this method is expected to reduce calculation costs and be more noise-resistant.

[0077] As described above, in this embodiment, the manager node 13 can calculate the position of the terminal 21. Here, this embodiment can send reception information including the received signal strength Y of beacon signals from the multiple terminals 14-1, 14-2, and 14-3 as metadata to the manager node 13 using a simple protocol. Therefore, this embodiment can calculate the position of the terminal 21 with an economical system configuration.

[0078] (Embodiment 3) A data management system according to an embodiment of the present disclosure will be described in detail with reference to FIGS. 11 to 14. FIG. 11 is a diagram illustrating an overview of a data management system 303. In this embodiment, one mobile beacon device 17 and one fixed beacon device 18 are provided instead of the three terminals 14-1, 14-2, and 14-3 in embodiment 2. The mobile beacon device 17 and the fixed beacon device 18 have the same functions as the terminals 14-1, 14-2, and 14-3. The fixed beacon device 18 is a stationary terminal as in embodiment 2, but differs from embodiment 2 in that the mobile beacon device 17 is mobile. Specifically, the data management system 303 includes a terminal 21, a management node 13, the mobile beacon device 17, and the fixed beacon device 18. The mobile beacon device 17 functions as a "first communication unit," the terminal 21 functions as a "second communication unit," and the management node 13 functions as a "calculation unit."

[0079] Specifically, the data management system 303 includes a mobile beacon device 17 and a terminal 21, at least one of which is movable, and a management node 13 that acquires reception information when a signal transmitted from the mobile beacon device 17 is received by the terminal 21 and calculates the position of the mobile beacon device 17 or the terminal 21 based on changes in the reception information obtained before and after the movement of either the mobile beacon device 17 or the terminal 21. In this embodiment, the management node 13 acquires reception information when a signal transmitted from the mobile beacon device 17 is received by the terminal 21 and calculates the position of the terminal 21 based on changes in the reception information obtained before and after the movement of the mobile beacon device 17.

[0080] A detailed description will be given below. The data management system 303 calculates the position of the terminal 21 using beacon signals emitted from the mobile beacon devices 17 and the fixed beacon devices 18. Specifically, the mobile beacon devices 17 and the fixed beacon devices 18 transmit beacon signals. The terminal 21 transmits received information obtained from the beacon signals as metadata. The management node 13 calculates the position of the terminal 21 based on the received metadata.

[0081] In this embodiment, a case will be described in which there is one each of the terminal 21, the mobile beacon device 17, and the fixed beacon device 18, but the combination of terminals and devices included in the data management system 303 according to this embodiment is not limited to this. Furthermore, each of the terminal 21, the mobile beacon device 17, and the fixed beacon device 18 may be a terminal equipped with the sensor device 11a described in Fig. 2, or may be a location determination terminal such as a BLE beacon that serves as a location metadata source. Alternatively, each of the terminal 21, the mobile beacon device 17, and the fixed beacon device 18 may be a terminal capable of collecting various secondary sensor data that can be used as metadata.

[0082] The movement of the mobile beacon device 17 is not limited to the case where it moves in response to an instruction from the management node 13, but also includes the case where an operator moves the mobile beacon device 17. Note that the movement direction of the mobile beacon device 17 is not limited to the direction indicated by the arrow M, and the mobile beacon device 17 can move in any direction.

[0083] The mobile beacon device 17 is configured to periodically transmit a beacon signal to the outside (S5-1, S5-2). The beacon signal transmitted by the mobile beacon device 17 includes unique information and transmitted signal strength information.

[0084] The fixed beacon device 18 is a terminal that was previously installed by an operator, and its installation location is managed by the management node 13. The fixed beacon device 18 is configured to periodically transmit a beacon signal to the outside in accordance with instructions from the management node 13 (S5-3). The beacon signal transmitted by the fixed beacon device 18 includes unique information and information on the intensity of the transmitted signal.

[0085] The terminal 21 transmits the received information obtained from the beacon signal as metadata via the low layer (layer 2) communication function. The management node 13 calculates the position of the terminal 21 based on the received information.

[0086] [Calculation of straight-line distance between terminal and beacon device] Based on instructions from the management node 13, each of the mobile beacon device 17 and the fixed beacon device 18 transmits a beacon signal at a predetermined transmission signal strength X to the terminal 21 whose position is to be calculated at any timing (steps S5-1, 5-2, and 5-3). Specifically, the mobile beacon device 17 emits a beacon signal to the terminal 21 at any timing before and after movement (S5-1, S5-2). Here, the mobile beacon device 17 and the fixed beacon device 18 transmit beacon signals at a common transmission signal strength of 10. In this embodiment, the combination of the strengths of the beacon signals transmitted by the mobile beacon device 17 and the fixed beacon device 18 is not limited to this, and each device may transmit a beacon signal of a different signal strength. The terminal 21 receives the beacon signal.

[0087] The terminal 21 stores the reception information of the beacon signal transmitted from the mobile beacon device 17 at any timing before and after the movement and the reception information of the beacon signal transmitted from the fixed beacon device 18 as metadata in the extension area of ​​the Probe Request and transmits it.

[0088] 12 is a block diagram illustrating the system configuration of the data management system 303. The data management system 303 includes the terminal 21, the management node 13, the mobile beacon device 17, and the fixed beacon device 18, as well as the network device 12.

[0089] The mobile beacon device 17 includes a beacon signal transmitting unit 17a. The beacon signal transmitting unit 17a is configured to periodically transmit a beacon signal to the outside (S5-1, S5-2). Similarly, the fixed beacon device 18 includes a beacon signal transmitting unit 18a. The beacon signal transmitting unit 18a is configured to periodically transmit a beacon signal to the outside (S5-3).

[0090] The terminal 21, network device 12, and management node 13 are the same as those in the second embodiment, and therefore detailed description thereof will be omitted. The communication protocol operation unit 21b of the terminal 21 transmits the Probe Request frame generated by the beacon signal receiving unit 21a to the network device 12 (S6). The communication protocol receiving unit 12a of the network device 12 reads metadata from the Probe Request frame received from the terminal 21, and sends it to the management node 13 (S8).

[0091] The operation of the data management system 303 will be described in detail using Figure 13, which is a sequence diagram explaining the transmission and reception of signals and data in the data management system 303. Each of the mobile beacon device 17 and the fixed beacon device 18 transmits a beacon signal with a predetermined transmission signal strength X to the terminal 21 whose position is to be calculated at any timing based on instructions from the management node 13 (S5-1, S5-2, and S5-3). Specifically, the mobile beacon device 17 emits a beacon signal to the terminal 21 at any timing before and after movement (S5-1, S5-2).

[0092] The terminal 21 receives beacon signals transmitted from the mobile beacon device 17 before and after the movement and measures the received signal strength of the beacon signal. The terminal 21 also receives beacon signals transmitted from the fixed beacon device 18 in the time period before and after the movement of the mobile beacon device 17 and measures the received signal strength of the beacon signal. Then, the terminal 21 stores the reception information of the mobile beacon device 17 and the fixed beacon device 18 as metadata in the extension field of the Probe Request and transmits it (steps S6-1, 6-2, and 6-3). Here, in this embodiment, the reception information includes unique information of the mobile beacon device 17 and the fixed beacon device 18, and transmission signal strength information and reception signal strength information of the mobile beacon device 17 and the fixed beacon device 18 before and after the movement of the mobile beacon device 17.

[0093] The network device 12 receives a Probe Request frame from the terminal 21, reads the metadata in the extension area of ​​the Probe Request frame (S7-1, S7-2, and S7-3), and sends it to the management node 13 (S8-1, S8-2, and S8-3). The metadata sent to the management node 13 is stored in the information storage unit 13c of the management node 13 and is used when calculating the position of the terminal 21. In addition, after calculating the relative distance between the terminal 21 and the mobile beacon device 17 after movement, the relative distance information between the terminal 21 and the mobile beacon device 17 is updated.

[0094] Next, a position determination method according to this embodiment will be described. Fig. 14 is a diagram illustrating the application of the triangulation method to this embodiment, and is a diagram illustrating the position determination method of the terminal 21 executed by the data management system 303 according to this embodiment.

[0095] Specifically, the method for determining the position of the terminal 21 executed by the data management system 303 includes the steps of acquiring reception information when a signal transmitted from the mobile beacon device 17 is received by the terminal 21, and calculating the position of the mobile beacon device 17 or the terminal 21 based on changes in the reception information obtained before and after movement of either the mobile beacon device 17 or the terminal 21.

[0096] By the procedure 1 described in the second embodiment, the distances (d1, d2, d3) between the terminal 21 and each of the mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18 are obtained, and a point is derived where the circumferences (C0, C1, C2) centered on the respective positions of the mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18 intersect. This point is calculated as the position of the terminal 21.

[0097] Here, in this embodiment, the mobile beacon device 17 is movable. Therefore, the management node 13 may acquire location information that can identify the geographical position of the mobile beacon device 17 and store the location information in the information storage unit 13c. In this case, the information processing unit 13b of the management node 13 calculates the location of the terminal 21 based on the location information and the received information transmitted from the terminal 21. Also, as described above, the "received information" may include information regarding the geographical location of the sender of the beacon signal. In this case, the management node 13 calculates the location of the terminal 21 based only on the "received information".

[0098] 14 is also a diagram illustrating the WCL method. According to the procedure 1 described in the second embodiment, the distances (d1, d2, d3) between the mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18 and the terminal 21 are obtained. "Weights" are calculated from these distances, and the position of the terminal 21 is calculated from the balance between the "weights." Compared to the three-point positioning method, it is expected to reduce calculation costs and be more resistant to noise.

[0099] In this way, in this embodiment, by moving the mobile beacon device 17 relative to the terminal 21, the position of the terminal 21 can be calculated with a simple configuration based on changes in the received signal strength of the beacon signal received by the terminal 21. Specifically, by using metadata related to the received signal strength of the beacon signal transmitted from the mobile beacon device 17 before movement and the received signal strength of the beacon signal transmitted from the mobile beacon device 17 after movement, the number of beacon devices prepared for calculating the position of the terminal 21 can be reduced.

[0100] Furthermore, in this embodiment, by sending the information received at the terminal 21 to the management node 13 as metadata using a simple protocol, it is possible to calculate the position of the terminal 21 with an economical system configuration.

[0101] (Variation of Embodiment 3) A variation of the data management system according to the embodiment of the present disclosure will be described in detail with reference to FIGS. 15 and 16. FIG. 15 is a diagram showing an overview of the data management system 303A. FIG. 16 is a sequence diagram explaining transmission and reception of signals and data in the data management system 303A. In the above description of Embodiment 3, a case has been described in which beacon signals are transmitted from the mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18, and the beacon signals are received by the terminal 21. However, the present disclosure is not limited to this, and the terminal 21 may be configured to transmit a beacon signal, and the beacon signals transmitted from the terminal 21 may be received by the mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18.

[0102] In this modified example, the management node 13 acquires reception information when a signal transmitted from the terminal 21 is received by the mobile beacon device 17, and calculates the position of the terminal 21 based on changes in the reception information obtained before and after the movement of the mobile beacon device 17.

[0103] As shown in Figures 15 and 16, the beacon signal from the terminal 21 is received by the mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18 (S5A-1, S5A-2, and S5A-3). The mobile beacon device 17 before movement, the mobile beacon device 17 after movement, and the fixed beacon device 18 receive the beacon signal, store the reception information obtained by the reception as metadata in the extension area of ​​the Probe Request frame, and transmit it (steps S6A-1, 6A-2, and 6A-3). As a result, the management node 13 can obtain the terminal-to-terminal distance d1 between the mobile beacon device 17 and the terminal 21 before movement, the terminal-to-terminal distance d2 between the mobile beacon device 17 and the terminal 21 after movement, and the terminal-to-terminal distance d3 between the fixed beacon device 18 and the terminal 21. Therefore, in this embodiment, the management node 13 can calculate the position of the terminal 21.

[0104] (Embodiment 4) A data management system according to an embodiment of the present disclosure will be described in detail with reference to Figs. 17 and 18. Fig. 17 is a diagram illustrating an overview of a data management system 304. In this embodiment, one mobile beacon device 19 is provided instead of the three terminals 14-1, 14-2, and 14-3 in embodiment 2. Specifically, the data management system 304 mainly includes a terminal 21, a management node 13, and the mobile beacon device 19. The mobile beacon device 19 functions as a "first communication unit," the terminal 21 functions as a "second communication unit," and the management node 13 functions as a "calculation unit."

[0105] That is, in this embodiment, the management node 13 acquires reception information when a signal transmitted from the mobile beacon device 19 is received by the terminal 21, and calculates the position of the terminal 21 based on changes in the reception information obtained before and after the movement of the mobile beacon device 19.

[0106] A detailed description will be given below. In this embodiment, a case will be described in which there is one terminal 21 and one mobile beacon device 19, but the combination of terminals and devices included in the data management system 304 according to this embodiment is not limited to this. Furthermore, each of the terminal 21 and the mobile beacon device 19 may be a terminal equipped with the sensor device 11a described in FIG. 2, or may be a location determination terminal such as a BLD beacon that serves as a location metadata source. Alternatively, each of the terminal 21 and the mobile beacon device 19 may be a terminal that can collect various secondary sensor data that can be used as metadata.

[0107] The movement of the mobile beacon device 19 is not limited to the case where it moves in response to an instruction from the management node 13, but also includes the case where an operator holds and moves the mobile beacon device 19. The mobile beacon device 19 is configured to periodically transmit a beacon signal to the outside in accordance with an instruction from the management node 13 (arrows (1) to (9) in the figure). The beacon signal transmitted by the mobile beacon device 19 includes the unique information of the mobile beacon device 19 and transmitted signal strength information.

[0108] The terminal 21 transmits the received information obtained from the beacon signal as metadata using a low-layer (layer 2) communication function. The management node 13 calculates the position of the terminal 21 based on the received information received via the network device 12.

[0109] [Calculation of terminal position] Suppose the mobile beacon device 19 is moved in a predetermined direction M1 + M2. The received signal strength of the beacon signal received by the terminal 21 changes in the order of (1), (2), (3), and (4) in the figure. In this case, if the mobile beacon device 19 starts moving in a direction approaching the terminal 21, there will be a point where the received signal strength of the beacon signal received by the terminal 21 is the largest. At this time, the management node 13 can obtain the minimum distance dmin-1 between the mobile beacon device 19 and the terminal 21 when the mobile beacon device 19 moves in the predetermined direction M1 + M2 based on the difference between the transmitted signal strength of the beacon signal and the received signal strength at the terminal 21.

[0110] Similarly, suppose the mobile beacon device 19 is moved in another direction, M3+M4. At this time, the received signal strength of the beacon signal received by the terminal 21 changes in the order of (5), (6), (7), and (8) in the figure. In this case, the minimum distance dmin-2 between the mobile beacon device 19 and the terminal 21 can be obtained. By repeating this and tracing the trajectory of the received signal strength, the position of the terminal 21 can be determined.

[0111] The operation of the data management system 304 will be described with reference to Fig. 18. Fig. 18 is a sequence diagram illustrating the transmission and reception of signals and data in the data management system 304.

[0112] The mobile beacon device 19 transmits a beacon signal at any timing before and after the movement (S9-1, S9-2, S9-3, S9-4, and S9-5). The terminal 21 stores the reception information of the beacon signal transmitted from the mobile beacon device 19 before and after the movement as metadata in the extension area of ​​the Probe Request and transmits it (steps S10-1, 10-2, 10-3, 10-4, and 10-5).

[0113] The network device 12 reads the metadata in the extension area from the Probe Request frame sent from the terminal 21 (S11-1, S11-2, S11-3, S11-4, and S11-5). The network device 12 sends the read metadata to the management node 13. The metadata sent to the management node 13 is stored in the information storage unit 13c of the management node 13. As a result, the received information included in the metadata is stored in the information storage unit 13c. Therefore, the management node 13 can calculate the position of the terminal 21 using the received information stored in the information storage unit 13c (S12-1, S12-2, S12-3, S12-4, S12-5). In addition, after calculating the relative distance between the terminal 21 and the mobile beacon device 19 after movement, the relative distance information between the terminal 21 and the mobile beacon device 19 in the information storage unit 13c is updated.

[0114] In this way, in this embodiment, by moving the mobile beacon device 19 relative to the terminal 21, the management node 13 can calculate the position of the terminal 21 with a simple configuration based on changes in the received signal strength of the beacon signal received by the terminal 21. Specifically, by using metadata regarding the signal strength of the beacon signal transmitted from the mobile beacon device 19 before and after movement, the number of beacon devices prepared for calculating the position of the terminal 21 can be reduced.

[0115] In addition, in this embodiment, reception information including the reception signal strength Y at the terminal 21 of the beacon signal from the mobile beacon device 19 can be sent as metadata to the management node 13 using a simple protocol. Therefore, in this embodiment, it is possible to calculate the position of the terminal 21 with an economical system configuration.

[0116] (Variation of Embodiment 4) A data management system according to an embodiment of the present disclosure will be described in detail with reference to Figs. 19 and 20. Fig. 19 is a diagram showing an overview of the data management system 304A. Fig. 20 is a sequence diagram explaining transmission and reception of signals and data in the data management system 304A. In the above description of Embodiment 4, a case has been described in which beacon signals are transmitted from the mobile beacon devices 19 before and after movement, and the beacon signals are received by the terminal 21. However, the scope of the present disclosure is not limited thereto, and the terminal 21 may be configured to transmit a beacon signal, and the mobile beacon devices 19 before and after movement may receive the beacon signal transmitted from the terminal 21.

[0117] In this modified example, the management node 13 acquires reception information when a signal transmitted from the terminal 21 is received by the mobile beacon device 19, and calculates the position of the terminal 21 based on changes in the reception information obtained before and after the movement of the mobile beacon device 19.

[0118] 19 and 20, the beacon signal from the terminal 21 is received by the mobile beacon device 19 before and after movement (S9A-1, S9A-2, and S9A-3). The mobile beacon device 19 before and after movement receives the beacon signal, stores the reception information obtained by the reception as metadata in the extension area of ​​the Probe Request frame, and transmits it (steps S10A-1, 10A-2, and 10A-3).

[0119] The network device 12 reads the metadata in the extension area from the Probe Request frame sent from the mobile beacon device 19 before and after movement (S11A-1, S11A-2, and S11A-3). The network device 12 sends the read metadata to the management node 13. The metadata sent to the management node 13 is stored in the information storage unit 13c of the management node 13 and is used when calculating the position of the terminal 21 (S12A-1, S12A-2, and S12A-3). In addition, after calculating the relative distance between the terminal 21 and the mobile beacon device 19 after movement, the relative distance information between the terminal 21 and the mobile beacon device 17 is updated.

[0120] [Other Modifications] In the above embodiment, the manager node calculates the location of the terminal based on the transmitted signal strength and received signal strength of the beacon signal. However, the present disclosure can use any information that changes depending on the distance between the terminals as the received information. For example, optical or acoustic signals may be used instead of beacon signals. Furthermore, the location of the terminal may be calculated based on other physical quantities such as time and frequency instead of or in addition to the strength.

[0121] In the above embodiment, the management node 13 calculates the position of the terminal 21 whose position is to be calculated based on the received signal strength at the terminal of the beacon signal transmitted by the mobile beacon device 17 or the fixed beacon device 18. However, the scope of the present disclosure is not limited to this. The management node 13 may calculate the position of the mobile beacon device 17 or the fixed beacon device 18 based on the received signal strength at the terminal 21 of the beacon signal transmitted by the mobile beacon device 17 or the fixed beacon device 18.

[0122] The terminal and device of the present disclosure can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided over a network. The program is a program for causing a computer to realize each function of the device according to the present disclosure, and a program for causing a computer to execute each procedure of the method executed by the device according to the present disclosure.

[0123] 11, 21: Terminal 21A: Existing terminal 11a: Sensor device 11b: Sensing data storage processing unit 11c: Device information storage processing unit 11d, 11d1, 11d2: Communication protocol operation unit 11e, 11e1, 11e2, 11e3: Metadata detection unit 11f: Metadata storage processing unit 11g: Instruction interpretation unit 12: Network device 12a: Communication protocol receiving unit 13: Management node 13a: Communication protocol operation unit 13b: Information processing unit 13c: Information storage unit 14, 14-1, 14-2, 14-3: Terminal 14A: Switch terminal 15: Data collection network 16: Metadata source 17: Mobile beacon device 18: Fixed beacon device 19: Mobile beacon device 17a, 18a, 19a: Beacon signal transmission unit 21b: Communication protocol operation unit 41: Frame 41a: Logical operator 41b: Source / destination identifier 41c: Main data area 41d: Extension area 301 to 304, 303A, 304A: Data management system

Claims

1. A system comprising: a first communication unit and a second communication unit, at least one of which is movable; and a calculation unit that acquires reception information when a signal transmitted from the first communication unit is received by the second communication unit, and calculates the position of the first communication unit or the second communication unit based on changes in the reception information obtained before and after movement of either the first communication unit or the second communication unit.

2. The system described in claim 1, wherein the second communication unit stores the received information as metadata in an extension area within a control system frame defined by a standardized wireless communication protocol, and transmits the metadata stored in the extension area to the calculation unit.

3. The system described in claim 1, wherein the calculation unit calculates the position of the first communication unit or the second communication unit based on the distance obtained from the received information before the movement and the distance obtained from the received information after the movement.

4. A positioning method executed by a system having a first communication unit and a second communication unit, at least one of which is movable, comprising the steps of: acquiring reception information when a signal transmitted from the first communication unit is received by the second communication unit; and calculating the position of the first communication unit or the second communication unit based on changes in the reception information obtained before and after movement of either the first communication unit or the second communication unit.

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