Position Inference Method, Fixed Wireless Device, Mobile Wireless Device, and Storage Medium

Abstract

In the method for inferring the position of a fixed wireless device according to the present invention, a first similarity between a first fingerprint measured by the fixed wireless device at a first timing and a second fingerprint measured by the mobile wireless device at a second timing and transmitted from the mobile wireless device is calculated, a second similarity between a third fingerprint measured by another fixed wireless device at the first timing and the second fingerprint is received from the other fixed wireless device, and the position of the mobile wireless device is determined based on a comparison result between the first similarity and the second similarity.

Description

Technical Field

[0001] The present invention relates to a position inference method, a position inference program, a fixed wireless device, and a mobile wireless device. Background Art

[0002] In recent years, with the development of wireless communication technology and the popularization of wireless terminals, the demand for position inference of wireless terminals applying wireless communication technology has increased.

[0003] For example, a system has been proposed that infers the position of a mobile device based on the received signal strength when a fixed device receives a wireless signal transmitted by a mobile device in a wireless mesh network composed of three or more fixed devices and one mobile device (for example, refer to Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication No. 2018 / 056149 Summary of the Invention

[0007] In the system of Patent Document 1, the position of the mobile device is inferred by a position inference device separate from the mobile device and the fixed device.

[0008] Therefore, in the system of Patent Document 1, in addition to the wireless mesh network composed of the fixed device and the mobile device, devices such as a network and a gateway for connecting the wireless mesh network to the position inference device are also required, resulting in higher costs.

[0009] A non-limiting embodiment of the present invention helps to provide a position inference method, a position inference program, and a mobile wireless device that can infer the position of a mobile wireless device at low cost.

[0010] A position inference method according to an embodiment of the present invention is a position inference method in a fixed wireless device, including the following steps: calculating a first similarity between a first fingerprint measured by the fixed wireless device at a first timing and a second fingerprint measured by the mobile wireless device at a second timing and transmitted from the mobile wireless device; receiving a second similarity between a third fingerprint measured by the other fixed wireless device at the first timing and the second fingerprint from the other fixed wireless device; and determining the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

[0011] The position inference program according to an embodiment of the present invention causes a fixed wireless device to perform the following processes: measure a first fingerprint at a first timing and store it; calculate a first similarity between the first fingerprint and a second fingerprint measured by the mobile wireless device at a second timing and transmitted from the mobile wireless device; receive a second similarity between a third fingerprint measured and stored by another fixed wireless device at the first timing and the second fingerprint from the other fixed wireless device; and determine the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

[0012] A fixed wireless device according to an embodiment of the present invention includes: a control circuit that calculates a first similarity between a first fingerprint measured by the fixed wireless device at a first timing and a second fingerprint measured by the mobile wireless device at a second timing and transmitted from the mobile wireless device; and a communication circuit that receives a second similarity between a third fingerprint measured by another fixed wireless device at the first timing and the second fingerprint from the other fixed wireless device, and the control circuit determines the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

[0013] A position inference method according to an embodiment of the present invention is a position inference method in a mobile wireless device, and includes the following steps: transmit a second fingerprint measured by the mobile wireless device at a second timing to a plurality of fixed wireless devices; receive a plurality of similarities between a plurality of fourth fingerprints measured by the plurality of fixed wireless devices at a first timing and the second fingerprint from the plurality of fixed wireless devices; and determine the position of the mobile wireless device based on the plurality of similarities.

[0014] The position inference program according to an embodiment of the present invention causes a mobile wireless device to perform the following processes: transmit a second fingerprint measured by the mobile wireless device at a second timing to a plurality of fixed wireless devices; receive a plurality of similarities between a plurality of fourth fingerprints measured by the plurality of fixed wireless devices at a first timing and the second fingerprint from the plurality of fixed wireless devices; and determine the position of the mobile wireless device based on the plurality of similarities.

[0015] A mobile wireless device according to an embodiment of the present invention includes: a transmission circuit that transmits a second fingerprint measured by the mobile wireless device at a second timing to a plurality of fixed wireless devices; a reception circuit that receives a plurality of similarities between a plurality of fourth fingerprints measured by the plurality of fixed wireless devices at a first timing and the second fingerprint from the plurality of fixed wireless devices; and a control circuit that determines the position of the mobile wireless device based on the plurality of similarities.

[0016] In addition, these inclusive or specific forms can be implemented by a system, apparatus, method, integrated circuit, computer program, or recording medium, or by any combination of a system, apparatus, method, integrated circuit, computer program, and recording medium.

[0017] According to an embodiment of the present invention, the position of a mobile wireless device can be inferred at low cost.

[0018] Further advantages and effects of an embodiment of the present invention will be clarified by the description and the drawings. These advantages and / or effects are provided by several embodiments and the features described in the description and the drawings, but it is not necessary to provide all of them in order to obtain one or more of the same features. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a diagram showing a structural example of a position inference system according to an embodiment;

[0020] Figure 2A is a diagram for explaining an example of a schematic operation in the training operation of the position inference system;

[0021] Figure 2B is a diagram for explaining an example of a schematic operation in the training operation of the position inference system;

[0022] Figure 2C is a diagram for explaining an example of a schematic operation in the training operation of the position inference system;

[0023] Figure 2D is a diagram for explaining an example of a schematic operation in the training operation of the position inference system;

[0024] Figure 3 is a diagram for explaining an example of a schematic operation in the position inference operation of the position inference system;

[0025] Figure 4 is a diagram showing a framework structural example of a wireless terminal;

[0026] Figure 5 is a diagram showing a structural example of a data packet;

[0027] Figure 6 is a flowchart showing an operation example of a wireless terminal as an anchor node;

[0028] Figure 7 is a flowchart showing an operation example of a wireless terminal as a mobile node;

[0029] Figure 8 is a diagram showing an example of a fingerprint;

[0030] Figure 9 This is a diagram showing an example of storing fingerprints;

[0031] Figure 10A This is a timing diagram showing an example of the operation of a location inference system;

[0032] Figure 10B This is a timing diagram showing an example of the operation of a location inference system. Detailed Embodiments

[0033] Hereinafter, embodiments of the present invention will be described in detail with appropriate reference to the accompanying drawings. However, sometimes overly detailed descriptions may be omitted. For example, sometimes the detailed descriptions of well-known matters or the repeated descriptions of substantially the same structures may be omitted. This is to avoid making the following descriptions unnecessarily lengthy and to make it easy for those skilled in the art to understand.

[0034] In addition, the accompanying drawings and the following descriptions are provided to enable those skilled in the art to fully understand the present invention, and they are not used to limit the subject matter recited in the claims.

[0035] Figure 1 This is a diagram showing an example of the structure of the location inference system 1 according to the embodiment. As Figure 1 shown, the location inference system 1 includes wireless terminals 101 to 105. Figure 1 The dotted lines shown indicate the connection of the wireless links between the wireless terminals 101 to 105. The wireless terminals 101 to 105 form a mesh network.

[0036] Among the wireless terminals 101 to 105, the wireless terminals 101 to 104 are fixed to the installation locations. On the other hand, the wireless terminal 105 is, for example, a movable wireless terminal carried by a user. The wireless terminal 105 is the terminal to be the object of location inference.

[0037] The wireless terminals 101 to 105 may also be referred to as nodes or wireless devices. In addition, the wireless terminals 101 to 104 with fixed installation locations may be referred to as anchor nodes or fixed wireless devices. The movable wireless terminal 105 may be referred to as a mobile node or a mobile wireless device.

[0038] The location inference system 1 is used, for example, in a work site such as a factory. For example, the wireless terminals 101 to 104 as anchor nodes are fixed to the workbenches set for each process in the factory. The wireless terminal 105 as a mobile node is carried by a worker (user) who moves between the processes and performs operations using the workbenches of each process.

[0039] The position inference system 1 infers when the wireless terminal 105 as a mobile node is near which wireless terminals 101 to 104 as anchor nodes. Thus, the position inference system 1 can, for example, track when a worker is performing which process operation. The inference can also be referred to as a determination.

[0040] The wireless terminals 101 to 105 can also send the inferred position of the wireless terminal 105 to, for example, a production management device (not shown).

[0041] The production management device can also analyze the movement path of the received wireless terminal 105. That is, the production management device can also analyze the actions of the worker carrying the wireless terminal 105 and calculate the processes for improving the worker's work efficiency.

[0042] In addition, the structure of the position inference system 1 is not limited to Figure 1 the example shown. For example, there can be one or more anchor nodes. There can also be two or more mobile nodes.

[0043] The operation of the position inference system 1 is divided into: a training operation for obtaining information for inferring the position of the wireless terminal 105; and a position inference operation for performing the position inference of the wireless terminal 105.

[0044] Figures 2A - 2D FIG. is a diagram illustrating an example of a schematic operation in the training operation of the position inference system 1. Figures 2A - 2D In, the same reference numerals are given to the same components as Figure 1 those shown.

[0045] Here, the fingerprint represents the received signal strength distribution of the wireless signals of the other wireless terminals 101 to 105 in each of the wireless terminals 101 to 105 (for example, refer to Figure 8 and Figure 9 ). The received signal strength of the received signal strength distribution is represented by, for example, RSSI (Receive Signal Strength Indicator). The fingerprint can also be referred to as a fingerprint vector.

[0046] In the training operation, the wireless terminals 101 to 104 as anchor nodes store (save) the fingerprints when the wireless terminal 105 as a mobile node is near the wireless terminals 101 to 104.

[0047] For example, as shown in Figure 2A , the user carrying the wireless terminal 105 moves near the wireless terminal 101. After the user moves near the wireless terminal 101, the user operates a switch (for example, presses a button) provided in the wireless terminal 101.

[0048] The switch is operated so that the wireless terminal 101 stores, for example, a fingerprint FP1 using the RSSI of wireless signals transmitted from other wireless terminals 102 to 105 as elements. Thereby, in the wireless terminal 101, the fingerprint FP1 when the wireless terminal 105 is located near the wireless terminal 101 is stored in advance. That is, in the wireless terminal 101, when the distance between the wireless terminal 101 and the wireless terminal 105 is closer than the distances between the other wireless terminals 102 to 104 and the wireless terminal 105, the fingerprint FP1 is stored in advance.

[0049] Next, the user carrying the wireless terminal 105 moves, for example, as Figure 2B shown, near the wireless terminal 102. After the user moves near the wireless terminal 102, the switch provided in the wireless terminal 102 is operated.

[0050] The switch is operated so that the wireless terminal 102 stores, for example, a fingerprint FP2 using the RSSI of wireless signals transmitted from other wireless terminals 101, 103 to 105 as elements. Thereby, in the wireless terminal 102, the fingerprint FP2 when the wireless terminal 105 is located near the wireless terminal 102 is stored in advance. That is, in the wireless terminal 102, when the distance between the wireless terminal 102 and the wireless terminal 105 is closer than the distances between the other wireless terminals 101, 103, 104 and the wireless terminal 105, the fingerprint FP2 is stored in advance.

[0051] Next, the user carrying the wireless terminal 105 moves, for example, as Figure 2C shown, near the wireless terminal 103. After the user moves near the wireless terminal 103, the switch provided in the wireless terminal 103 is operated.

[0052] The switch is operated so that the wireless terminal 103 stores, for example, a fingerprint FP3 using the RSSI of wireless signals transmitted from other wireless terminals 101, 102, 104, 105 as elements. Thereby, in the wireless terminal 103, the fingerprint FP3 when the wireless terminal 105 is located near the wireless terminal 103 is stored in advance. That is, in the wireless terminal 103, when the distance between the wireless terminal 103 and the wireless terminal 105 is closer than the distances between the other wireless terminals 101, 102, 104 and the wireless terminal 105, the fingerprint FP3 is stored in advance.

[0053] Next, the user carrying the wireless terminal 105 moves, for example, as Figure 2D shown, near the wireless terminal 104. After the user moves near the wireless terminal 104, the switch provided in the wireless terminal 104 is operated.

[0054] The switch is operated so that the wireless terminal 104 stores, for example, a fingerprint FP4 having the RSSI of the wireless signals transmitted from other wireless terminals 101 to 103 and 105 as elements. Thus, in the wireless terminal 104, the fingerprint FP4 when the wireless terminal 105 is located near the wireless terminal 104 is pre-stored. That is, in the wireless terminal 104, when the distance between the wireless terminal 104 and the wireless terminal 105 is closer than the distances between the other wireless terminals 101 to 103 and the wireless terminal 105, the fingerprint FP3 is pre-stored.

[0055] In this way, through the training operation, fingerprints FP1 to FP4 when the wireless terminal 105 as a mobile node is located nearby are stored in the wireless terminals 101 to 104 as anchor nodes (for example, refer to Figure 2D ).

[0056] Figure 3 FIG. is a diagram illustrating an example of a rough operation in the position inference operation of the position inference system 1. Figure 3 In, the same reference numerals are given to the same components as Figure 1 above. Figure 3 In, the illustration of the dotted lines indicating the connection of the wireless links is omitted.

[0057] In the wireless terminals 101 to 104, through the Figures 2A - 2D training operation described above, fingerprints FP1 to FP4 when the wireless terminal 105 as a mobile node is located nearby are stored.

[0058] In the position inference operation, the wireless terminal 105 as a mobile node periodically calculates (generates), for example, a fingerprint FP5 having the RSSI of the wireless signals transmitted from the wireless terminals 101 to 104 as anchor nodes as elements. The wireless terminal 105 transmits the calculated fingerprint FP5 to the wireless terminals 101 to 104 as shown by the arrow A1.

[0059] Each of the wireless terminals 101 to 104 calculates (computes) the similarity between the fingerprint FP5 transmitted from the wireless terminal 105 and the fingerprints FP1 to FP4 stored in the training operation.

[0060] For example, the wireless terminal 101 calculates the similarity between the fingerprint FP5 transmitted from the wireless terminal 105 and the fingerprint FP1 stored in the training operation. The wireless terminal 102 calculates the similarity between the fingerprint FP5 transmitted from the wireless terminal 105 and the fingerprint FP2 stored in the training operation. The wireless terminal 103 calculates the similarity between the fingerprint FP5 transmitted from the wireless terminal 105 and the fingerprint FP3 stored in the training operation. The wireless terminal 104 calculates the similarity between the fingerprint FP5 transmitted from the wireless terminal 105 and the fingerprint FP4 stored in the training operation.

[0061] After calculating the similarity of the fingerprints respectively, the wireless terminals 101 to 104 send the calculated similarity of the fingerprints to other wireless terminals 101 to 105.

[0062] For example, as shown by arrow A2a in Figure 3 , the wireless terminal 101 broadcasts the calculated similarity to other wireless terminals 102 to 105. As shown by arrow A2b in Figure 3 , the wireless terminal 102 broadcasts the calculated similarity to other wireless terminals 101, 103 to 105. As shown by arrow A2c in Figure 3 , the wireless terminal 103 broadcasts the calculated similarity to other wireless terminals 101, 102, 104, 105. As shown by arrow A2d in Figure 3 , the wireless terminal 104 broadcasts the calculated similarity to other wireless terminals 101 to 103, 105.

[0063] The wireless terminals 101 to 105 respectively infer the position of the wireless terminal 105 based on the similarities sent from other wireless terminals 101 to 104. For example, the wireless terminals 101 to 105 respectively infer that: the wireless terminal 105 is located near the wireless terminal 101 to 104 that has sent the highest similarity.

[0064] For example, it is assumed that the user carrying the wireless terminal 105 is working at the workbench where the wireless terminal 102 is fixed. That is, it is assumed that the wireless terminal 105 is located near the wireless terminal 102 as shown in Figure 3 .

[0065] In this case, the fingerprint FP5 of the wireless terminal 105 is most similar to the fingerprint FP2 stored in the wireless terminal 102. That is, when the wireless terminal 105 is located near the wireless terminal 102, Figure 3 the fingerprint FP5 of the wireless terminal 105 in

[0066] is most similar to the fingerprint FP2 stored in the wireless terminal 102. In other words, compared with other similarities, the similarity between the fingerprint FP5 and the fingerprint FP2 is the highest. Figure 3 Therefore, in the example of

[0067] , the wireless terminals 101 to 105 respectively infer that: the wireless terminal 105 is located near the wireless terminal 102 that has sent the highest similarity.

[0068] Figure 4 This is a diagram showing an example of the frame structure of the wireless terminal 101. Since the wireless terminals 101 to 105 have the same frame structure, the frame structure of the wireless terminal 101 will be described in Figure 4 the following.

[0069] As shown in Figure 2, the wireless terminal 101 includes a wireless communication unit 11, a control unit 12, an input / output unit 13, and a storage unit 14.

[0070] The wireless communication unit 11 (transmission unit, reception unit) performs wireless communication with other wireless terminals 102 to 105. The wireless communication is, for example, low-power communication using the 920 MHz band, IEEE802.15.4, Zigbee using the 2.4 GHz band, Bluetooth (registered trademark), wireless LAN (IEEE802.11b / g / n), wireless LAN using the 5 GHz band (IEEE802.11a / ac) or DSRC, wireless LAN using the 60 GHz band (IEEE802.11ad), wireless communication using residential PHS, LTE, or 5G. The wireless communication unit 11 (reception unit) outputs the received data and the RSSI of the received wireless signal (received data packet). In addition, the wireless communication unit 11 can also communicate with a production management device (not shown).

[0071] The control unit 12 controls each unit. The control unit 12 is constituted by, for example, a CPU (Central Processing Unit). The control unit 12 performs processing for sending and receiving data packets, storage processing of fingerprints aggregating the RSSIs of multiple transmission sources (wireless terminals 102 to 105), calculation processing of the similarity of the fingerprints, and position inference processing of the wireless terminal 105 based on comparison of the similarities sent from other wireless terminals 102 to 104, etc.

[0072] The input / output unit 13 is, for example, an input device such as a switch or a button device. In addition, the input / output unit 13 is, for example, a sensor device such as an acceleration sensor or a human perception sensor. In addition, the input / output unit 13 is, for example, an output device such as an LED (Light Emitting Diode), a display, or a speaker.

[0073] A program for the operation of the control unit 12 is stored in the storage unit 14. In addition, data for the control unit 12 to perform calculation processing, or data for the control unit 12 to control each unit, etc. are stored in the storage unit 14. For example, a node list and fingerprints are stored in the storage unit 14. The storage unit 14 may also be composed of storage devices such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, and HDD (Hard Disk Drive).

[0074] Figure 5 is a diagram showing a structural example of the data packet 50. The wireless terminals 101 to 105 broadcast Figure 5 the data packet 50 shown via the wireless communication unit 11 (transmission unit). Thereby, the wireless terminals 101 to 105 infer the position of the wireless terminal 105 within the mesh network.

[0075] As Figure 3 shown, the data packet 50 has the following regions, namely, a region of a destination address 501, a source address 502, a node type 503, a sequence number 504, a query field 505, and a response field 506.

[0076] Address information related to the wireless terminal that is the destination of the data packet 50 is stored in the destination address 501. For example, in the case of broadcasting the data packet 50, a specified broadcast address (e.g., all 1s) is stored in the destination address 501. In the case of unicasting the data packet 50, the address at the wireless terminal that is the destination is stored in the destination address 501.

[0077] The address of the wireless terminal that is the source of the data packet 50 is stored in the source address 502.

[0078] Node type information indicating whether the wireless terminal that is the source of the data packet 50 is an anchor node or a mobile node is stored in the node type 503. For example, in the case where the wireless terminals 101 to 104 send the data packet 50, node type information indicating an anchor node is stored in the node type 503. In the case where the wireless terminal 105 sends the data packet 50, node type information indicating a mobile node is stored in the node type 503.

[0079] The node type information may also be set by the user via an input / output unit such as a key device during initial setting. The set node type information is stored in the storage unit of the wireless terminal.

[0080] In addition, for example, node category information can also be set in the wireless terminal based on signals from input / output units such as acceleration sensors. For example, the control unit of the wireless terminal determines whether it is an anchor node or a mobile node based on the signal from the acceleration sensor. When the control unit of the wireless terminal determines that it is an anchor node, it stores the node category information indicating the anchor node in the storage unit. When the control unit of the wireless terminal determines that it is a mobile node, it stores the node category information indicating the mobile node in the storage unit.

[0081] The sequence number indicating the order (or ID) of the data packet is stored in sequence number 504.

[0082] Data related to the query for other wireless terminals (query information) is stored in the query field 505. For example, the wireless terminal 105 that is the object of location inference stores the fingerprint at the wireless terminal 105 in the query field 505 and broadcasts it to other wireless terminals 101 - 104 (for example, refer to Figure 3 arrow A1).

[0083] Data related to the response to the query from other wireless terminals (response information) is stored in the response field 506. For example, when a fingerprint is stored in the query field 505, each of the wireless terminals 101 - 104 calculates the similarity between the fingerprint stored in the query field 505 and the fingerprint obtained through the training operation. Each of the wireless terminals 101 - 104 stores the calculated similarity in the response field 506 and broadcasts the data packet 50 (for example, refer to Figure 3 arrows A2a - A2d). Thus, each of the wireless terminals 101 - 105 can obtain the similarity of the fingerprints calculated by the wireless terminals 101 - 104.

[0084] Hereinafter, the data packet 50 is sometimes referred to as a BC (BroadCast) data packet.

[0085] Figure 6 It is a flowchart showing an operation example of the wireless terminal 101 as an anchor node.

[0086] The control unit 12 of the wireless terminal 101 refers to the storage unit 14 to obtain the node category information. When the node category information obtained from the storage unit 14 indicates that it is an anchor node, the control unit 12 of the wireless terminal 101 executes the Figure 6 processing of the flowchart shown. In addition, the wireless terminal 101 is an anchor node. Therefore, the control unit 12 of the wireless terminal 101 executes the Figure 6 processing of the flowchart shown.

[0087] In step S301, the control unit 12 of the wireless terminal 101 broadcasts the BC data packet via the wireless communication unit 11 (transmission unit).

[0088] In step S302, when the control unit 12 of the wireless terminal 101 receives BC data packets sent by other wireless terminals 102 to 105 in the wireless communication unit 11 (reception unit), it stores in the storage unit 14 a fingerprint that is a set of the source address of the received BC data packet and the RSSI of the received BC data packet.

[0089] The fingerprint can also be a list (vector) of elements that are the reception strengths of BC data packets sent from other wireless terminals 102 to 105 received during a specified time period up to the present (e.g., a 1-second period up to the present). Each element of the fingerprint is updated each time a BC data packet is received, and the fingerprint has the latest elements.

[0090] In step S303, when, for example, the switch of the input / output unit 13 of the wireless terminal 101 is pressed and a specified signal is output from the input / output unit 13, the control unit 12 of the wireless terminal 101 stores the current fingerprint as a saved fingerprint in the storage unit 14. The saved fingerprint corresponds to, for example, Figures 2A - 2D the fingerprints FP1 to FP4 described in []. Hereinafter, the specified signal that triggers the storage of the saved fingerprint is sometimes referred to as a fingerprint save command.

[0091] In step S304, when a fingerprint is stored in the query field 505 of the BC data packet received in the wireless communication unit 11 (reception unit) of the wireless terminal 101, the control unit 12 calculates the similarity between the saved fingerprint stored in the storage unit 14 and the fingerprint stored in the query field 505.

[0092] In addition, the wireless terminal 105, which is a mobile node, stores the fingerprint of the wireless terminal 105 in the query field 505 and broadcasts the BC data packet (e.g., refer to Figure 7 S401, S403 of []). Therefore, the control unit 12 of the wireless terminal 101 calculates the similarity between the saved fingerprint of the wireless terminal 101 stored in the storage unit 14 and the fingerprint of the wireless terminal 105.

[0093] After calculating the similarity, the control unit 12 of the wireless terminal 101 saves the calculated similarity (score), the sequence number of the received BC data packet, and the source address of the received BC data packet (the address of the wireless terminal 105 that is the object of location inference) in the response field 506 of the BC data packet to be sent next (sent in S301).

[0094] Other wireless terminals 102 to 104 that serve as anchor nodes also calculate the similarity in the same way as wireless terminal 101 and broadcast a BC packet that stores the calculated similarity, the sequence number of the received BC packet, and the source address of the received BC packet (the address of wireless terminal 105 that is the object of location inference) in the response field 506. Through this broadcast, wireless terminal 101 obtains the similarities of the fingerprints calculated by each of wireless terminals 102 to 104, and in the next step S305, determines near which of wireless terminals 101 to 104 the wireless terminal 105 that is the object of location inference is located.

[0095] In step S305, when the response field 506 of the BC packet received by the wireless communication unit 11 (reception unit) of wireless terminal 101 stores the similarity, the sequence number, and the address of wireless terminal 105, the control unit 12 of wireless terminal 101 stores the source address of the received BC packet and the response information stored in the response field 506 in the storage unit 14.

[0096] The control unit 12 of wireless terminal 101 compares the similarities for wireless terminal 105 among the response information stored in the storage unit 14 that has the same sequence number (the same fingerprint queried by the same location inference object node at the same time). Moreover, the control unit 12 of wireless terminal 101 determines that wireless terminal 105 is located near the wireless terminal 101 to 104 with the maximum similarity. The control unit 12 may also send the determination result of the location of wireless terminal 105 inferred via the wireless communication unit 11 to, for example, an external production management device.

[0097] In step S306, if it is to end the communication operation (S306 is "yes"), then the control unit 12 of wireless terminal 101 ends Figure 6 the operation of the flowchart. If the communication operation is not to be ended (S306 is "no"), then the control unit 12 of wireless terminal 101 transfers the process to step S301. The communication end operation can be performed by the user operating the input / output unit of wireless terminals 101 to 105. Wireless terminals 101 to 105 can send a communication end command to other wireless terminals when receiving an operation from the user via the input / output unit. Wireless terminals 101 to 105 can also determine to end the communication operation by receiving a communication end command from other wireless terminals.

[0098] In addition, wireless terminals 102 to 104 are also anchor nodes and execute Figure 6 the processing of the flowchart shown. Wireless terminals 101 to 104 can also periodically execute Figure 6 the flowchart shown.

[0099] Figure 7This is a flowchart showing an operation example of the wireless terminal 105 as a mobile node.

[0100] The control unit of the wireless terminal 105 refers to the storage unit to obtain node category information. When the node category information obtained from the storage unit indicates that it is a mobile node, the control unit of the wireless terminal 105 executes Figure 7 the processing of the flowchart shown. In addition, the wireless terminal 105 is a mobile node. Therefore, the control unit of the wireless terminal 105 executes Figure 7 the processing of the flowchart shown. The control unit of the wireless terminal 105 may also periodically execute Figure 7 the processing of the flowchart shown.

[0101] Figure 7 The processing of steps S401 and S402 shown is the same as the processing of steps S301 and S302 described in Figure 6 , so the description thereof is omitted.

[0102] In step S403, the control unit of the wireless terminal 105 saves the fingerprint stored in S402 in the query field 505 of the BC data packet to be sent next (sent in S401). Through this fingerprint saving process, the wireless terminals 101 to 104 as anchor nodes can each obtain the fingerprint of the wireless terminal 105 as a mobile node, and can each calculate the similarity between the saved fingerprint stored in the storage unit and the fingerprint of the wireless terminal 105 (for example, refer to Figure 6 S304).

[0103] Figure 7 The processing of steps S404 and S405 shown is the same as the processing of steps S305 and S306 described in Figure 6 , so the description thereof is omitted.

[0104] Figure 8 This is a diagram showing an example of the fingerprint 600. For example, through the processing of step S302 described in Figure 6 , the fingerprint 600 is stored in the storage units of the wireless terminals 101 to 104. In addition, for example, through the processing of step S402 described in Figure 7 , the fingerprint 600 is stored in the storage unit of the wireless terminal 105.

[0105] As Figure 8 shown, the fingerprint 600 is composed of the source address of the source node contained in the BC data packet and the RSSI measured based on the BC data packet. The fingerprint 600 may also include multiple groups of source addresses and RSSIs.

[0106] When the wireless terminal receives a BC packet containing a new source address for transmission, it updates the fingerprint 600 by adding a new group of the source address for transmission and the RSSI. For example, when a new wireless terminal is added to the location inference system 1, the wireless terminal adds a group of the source address for transmission and the RSSI of the added wireless terminal to update the fingerprint 600.

[0107] When the wireless terminal receives a BC packet having the source address for transmission included in the fingerprint 600, it updates the RSSI corresponding to the source address for transmission to the newly measured RSSI.

[0108] Figure 9 This is a diagram showing an example of storing the fingerprint 700. For example, through the processing of step S303 described in Figure 6 the fingerprint 700 for storage is stored in the storage units of the wireless terminals 101 to 104.

[0109] The stored fingerprint 700 is the fingerprint 600 stored in the storage unit when a fingerprint storage command is output from the input / output unit of the wireless terminal.

[0110] For example, the fingerprint 600 is updated by receiving a BC packet. In contrast, the stored fingerprint 700 is updated when a fingerprint storage command is output from the input / output unit of the wireless terminal, and is updated to the fingerprint 600 stored in the storage unit.

[0111] As Figure 9 shown, the stored fingerprint 700 has an option area. For example, the time when the stored fingerprint 700 is updated is saved in the option.

[0112] In addition, the wireless terminal can also send its own fingerprint 600 or stored fingerprint 700 to other wireless terminals using the query field of the BC packet. At this time, it can also be that, after the wireless terminal receives a packet sent from another wireless terminal, it saves the fingerprint stored in the query field of the received packet in the option for storing the fingerprint in a manner including the source address for transmission.

[0113] It can also be configured such that, in the option for storing the fingerprint, in addition to storing the fingerprint measured by the mobile node, the wireless terminal also stores the fingerprint measured by the anchor node when receiving a BC packet from the mobile node, or the fingerprint measured when BC packets are sent and received between anchor nodes. Additionally, the address of the wireless terminal 105 that is the object of location inference can also be saved in the option.

[0114] An example of calculating the similarity of fingerprints will be described.

[0115] The cosine similarity can be used to calculate the similarity between the fingerprint of the wireless terminal of the mobile node that is the object of location inference and the stored fingerprint of the wireless terminal of the anchor node.

[0116] For example, the fingerprint of a wireless terminal as a mobile node can be regarded as a vector with RSSI as an element. The saved fingerprint of a wireless terminal as an anchor node can be regarded as a vector with RSSI as an element. The formula for calculating the cosine similarity between the fingerprint vector of a wireless terminal as a mobile node and the saved fingerprint vector of a wireless terminal as an anchor node is represented by Equation (1).

[0117]

[0118] Fingerprint vector of a wireless terminal as a mobile node

[0119] Saved fingerprint vector of a wireless terminal as an anchor node

[0120] It can be considered that the closer the value of the cosine similarity in Equation (1) is to 1, the more similar the fingerprint vector of the wireless terminal as a mobile node is to the saved fingerprint vector of the wireless terminal as an anchor node.

[0121] In addition, the method for calculating the similarity is not limited to the cosine similarity. For the method for calculating the similarity, other methods such as the reciprocal of the Euclidean distance and the Pearson correlation coefficient can also be used.

[0122] Figure 10A and Figure 10B is a timing chart showing an operation example of the position inference system 1. Figure 10A and Figure 10B In, it is assumed that the wireless terminal 105 is located near the wireless terminal 104.

[0123] In step S5001, the wireless terminal 101 sends a BC data packet.

[0124] The destination address of the BC data packet stores the broadcast address. The source address of the BC data packet stores the address of the wireless terminal 101. The node category of the BC data packet stores node category information indicating an anchor node. The sequence number of the BC data packet stores 1.

[0125] In addition, each of the wireless terminals 102 to 105 receives the BC data packet sent through step S5001, and measures the RSSI of the received BC data packet. Each of the wireless terminals 102 to 105 updates the fingerprint stored in the storage unit based on the measured RSSI.

[0126] In step S5002, the wireless terminal 102 sends a BC data packet.

[0127] The broadcast address is stored in the destination address of the BC packet. The address of the wireless terminal 102 is stored in the source address of the BC packet. Node category information indicating the anchor node is stored in the node category of the BC packet. 2 is stored in the sequence number of the BC packet.

[0128] In addition, each of the wireless terminals 101, 103 to 105 receives the BC packet transmitted through step S5002, and measures the RSSI of the received BC packet. Each of the wireless terminals 101, 103 to 105 updates the fingerprint stored in the storage unit based on the measured RSSI.

[0129] In step S5003, the wireless terminal 103 transmits a BC packet.

[0130] The broadcast address is stored in the destination address of the BC packet. The address of the wireless terminal 103 is stored in the source address of the BC packet. Node category information indicating the anchor node is stored in the node category of the BC packet. 3 is stored in the sequence number of the BC packet.

[0131] In addition, each of the wireless terminals 101, 102, 104, 105 receives the BC packet transmitted through step S5003, and measures the RSSI of the received BC packet. Each of the wireless terminals 101, 102, 104, 105 updates the fingerprint stored in the storage unit based on the measured RSSI.

[0132] In step S5004, the wireless terminal 104 transmits a BC packet.

[0133] The broadcast address is stored in the destination address of the BC packet. The address of the wireless terminal 104 is stored in the source address of the BC packet. Node category information indicating the anchor node is stored in the node category of the BC packet. 4 is stored in the sequence number of the BC packet.

[0134] In addition, each of the wireless terminals 101 to 103, 105 receives the BC packet transmitted through step S5004, and measures the RSSI of the received BC packet. Each of the wireless terminals 101 to 103, 105 updates the fingerprint stored in the storage unit based on the measured RSSI.

[0135] In step S5005, the wireless terminal 105 transmits a BC packet.

[0136] The broadcast address is stored in the destination address of the BC packet. The address of the wireless terminal 105 is stored in the source address of the BC packet. Node category information indicating the mobile node is stored in the node category of the BC packet. 5 is stored in the sequence number of the BC packet.

[0137] In addition, each of the wireless terminals 101 to 104 receives the BC data packet transmitted through step S5005, and measures the RSSI of the received BC data packet. Each of the wireless terminals 101 to 104 updates the fingerprint stored in the storage unit based on the measured RSSI.

[0138] Here, the user carrying the wireless terminal 105 operates the input / output unit of the wireless terminal 104 (for example, presses a switch).

[0139] In step S5006, the input / output unit of the wireless terminal 104 outputs a fingerprint save command corresponding to the user's operation. Corresponding to the output of the fingerprint save command, the wireless terminal 104 stores the fingerprint stored in the storage unit as a saved fingerprint in the storage unit.

[0140] In addition, in the following description, it is assumed that the other wireless terminals 101 to 103 serving as anchor nodes also store saved fingerprints in the storage unit. That is, the wireless terminal 101 stores the saved fingerprint when the wireless terminal 105 is near the wireless terminal 101. The wireless terminal 102 stores the saved fingerprint when the wireless terminal 105 is near the wireless terminal 102. The wireless terminal 103 stores the saved fingerprint when the wireless terminal 105 is near the wireless terminal 103.

[0141] It can be that in steps S5007 to S5010, the wireless terminals 101 to 104 send BC data packets in the same manner as the processing in steps S5001 to S5004. Thereby, the wireless terminals 101 to 104 send and receive BC data packets to each other, so that each wireless terminal measures the latest RSSI at any time and updates the fingerprint 600.

[0142] In Figure 10B step S5011, the wireless terminal 105 sends a BC data packet.

[0143] The broadcast address is saved in the destination address of the BC data packet. The address of the wireless terminal 105 is saved in the source address of the BC data packet. The node category information indicating a mobile node is saved in the node category of the BC data packet. The number 10 is saved in the sequence number of the BC data packet. The fingerprint (the latest fingerprint) stored in the wireless terminal 105 is saved in the query field of the BC data packet.

[0144] In step S5012a, the wireless terminal 101 receives the BC data packet sent through S5011. The fingerprint of the wireless terminal 105 is stored in the query field of the BC data packet sent through S5011. Therefore, the wireless terminal 101 calculates the similarity between the fingerprint of the wireless terminal 105 stored in the query field of the BC data packet and the saved fingerprint stored in the storage unit. Therefore, the BC data packet sent from the wireless terminal 105 through S5011 becomes an opportunity to calculate the similarity, and the sequence number of the BC data packet that becomes an opportunity to calculate the similarity is 10.

[0145] In step S5012b, the wireless terminal 102 receives the BC data packet sent through S5011. The fingerprint of the wireless terminal 105 is stored in the query field of the BC data packet sent through S5011. Thus, the wireless terminal 102 calculates the similarity between the fingerprint of the wireless terminal 105 stored in the query field of the BC data packet and the saved fingerprint stored in the storage unit. Therefore, the BC data packet sent from the wireless terminal 105 through S5011 becomes an opportunity to calculate the similarity, and the sequence number of the BC data packet that becomes an opportunity to calculate the similarity is 10.

[0146] In step S5012c, the wireless terminal 103 receives the BC data packet sent through S5011. The fingerprint of the wireless terminal 105 is stored in the query field of the BC data packet sent through S5011. Thus, the wireless terminal 103 calculates the similarity between the fingerprint of the wireless terminal 105 stored in the query field of the BC data packet and the saved fingerprint stored in the storage unit. Therefore, the BC data packet sent from the wireless terminal 105 through S5011 becomes an opportunity to calculate the similarity, and the sequence number of the BC data packet that becomes an opportunity to calculate the similarity is 10.

[0147] In step S5012d, the wireless terminal 104 receives the BC data packet sent through S5011. The fingerprint of the wireless terminal 105 is stored in the query field of the BC data packet sent through S5011. Thus, the wireless terminal 104 calculates the similarity between the fingerprint of the wireless terminal 105 stored in the query field of the BC data packet and the saved fingerprint stored in the storage unit. Therefore, the BC data packet sent from the wireless terminal 105 through S5011 becomes an opportunity to calculate the similarity, and the sequence number of the BC data packet that becomes an opportunity to calculate the similarity is 10.

[0148] In addition, as described above, the wireless terminal 105 as a mobile node is located near the wireless terminal 104 as an anchor node. Thus, the similarity calculated by the wireless terminal 104 becomes the highest. For example, in Figure 10BIn the example, the similarity in wireless terminal 101 is "0.2". The similarity in wireless terminal 102 is "0.5". The similarity in wireless terminal 103 is "0.4". The similarity in wireless terminal 104 is "0.8".

[0149] In step S5013, wireless terminal 101 sends a BC data packet. That is, wireless terminal 101 receives a BC data packet with a fingerprint saved in the query field, calculates the similarity, and then sends a corresponding BC data packet.

[0150] The broadcast address is saved in the destination address of the BC data packet. The address of wireless terminal 101 is saved in the source address of the BC data packet. The node category information indicating the anchor node is saved in the node category of the BC data packet. The number 11 is saved in the sequence number of the BC data packet. The similarity calculated through step S5012a, the sequence number of the BC data packet that triggered the similarity calculation (sequence number 10 of the BC data packet sent through S5011), and the address of the mobile node for which the similarity was calculated (address of wireless terminal 105) are saved in the response field of the BC data packet.

[0151] In addition, wireless terminals 102 to 105 that receive the BC data packet of wireless terminal 101 store the address of wireless terminal 101 in correspondence with the response information saved in the response field of the BC data packet in storage unit 14.

[0152] In step S5014, wireless terminal 102 sends a BC data packet. That is, wireless terminal 102 receives a BC data packet with a fingerprint saved in the query field, calculates the similarity, and then sends a corresponding BC data packet.

[0153] The broadcast address is saved in the destination address of the BC data packet. The address of wireless terminal 102 is saved in the source address of the BC data packet. The node category information indicating the anchor node is saved in the node category of the BC data packet. The number 12 is saved in the sequence number of the BC data packet. The similarity calculated through step S5012b, the sequence number of the BC data packet that triggered the similarity calculation (sequence number 10 of the BC data packet sent through S5011), and the address of the mobile node for which the similarity was calculated (address of wireless terminal 105) are saved in the response field of the BC data packet.

[0154] In addition, wireless terminals 101, 103 to 105 that receive the BC data packet of wireless terminal 102 store the address of wireless terminal 102 in correspondence with the response information saved in the response field of the BC data packet in the storage unit.

[0155] In step S5015, the wireless terminal 103 sends a BC data packet. That is, the wireless terminal 103 receives a BC data packet with a fingerprint saved in the query field, calculates the similarity, and then sends a corresponding BC data packet.

[0156] The broadcast address is saved in the destination address of the BC data packet. The address of the wireless terminal 103 is saved in the source address of the BC data packet. The node category information indicating the anchor node is saved in the node category of the BC data packet. The number 13 is saved in the sequence number of the BC data packet. The similarity calculated through step S5012c, the sequence number of the BC data packet that triggered the similarity calculation (sequence number 10 of the BC data packet sent through S5011), and the address of the mobile node for which the similarity was calculated (address of the wireless terminal 105) are saved in the response field of the BC data packet.

[0157] In addition, the wireless terminals 101, 102, 104, and 105 that receive the BC data packet of the wireless terminal 103 store the address of the wireless terminal 103 and the response information saved in the response field of the BC data packet in a corresponding manner in the storage unit.

[0158] In step S5016, the wireless terminal 104 sends a BC data packet. That is, the wireless terminal 104 receives a BC data packet with a fingerprint saved in the query field, calculates the similarity, and then sends a corresponding BC data packet.

[0159] The broadcast address is saved in the destination address of the BC data packet. The address of the wireless terminal 104 is saved in the source address of the BC data packet. The node category information indicating the anchor node is saved in the node category of the BC data packet. The number 14 is saved in the sequence number of the BC data packet. The similarity calculated through step S5012d, the sequence number of the BC data packet that triggered the similarity calculation (sequence number 10 of the BC data packet sent through S5011), and the address of the mobile node for which the similarity was calculated (address of the wireless terminal 105) are saved in the response field of the BC data packet.

[0160] In addition, the wireless terminals 101 to 103 and 105 that receive the BC data packet of the wireless terminal 104 store the address of the wireless terminal 104 and the response information saved in the response field of the BC data packet in a corresponding manner in the storage unit.

[0161] Through the sending of the BC data packets in steps S5013 to S5016, the wireless terminals 101 to 105 can share the similarities calculated by the wireless terminals 101 to 104 respectively.

[0162] In step S5017a, the wireless terminal 101 compares the similarities calculated by each of the wireless terminals 101 to 104. The wireless terminal 101 determines that the wireless terminal 105 is located near the wireless terminal that calculates the maximum similarity.

[0163] In addition, the timing for the wireless terminal to compare the similarities stored in the storage unit can be when the number of stored similarities reaches a specified number, or can be periodically compared at regular intervals. Alternatively, each time a BC data packet storing a similarity in the response field is received from another wireless terminal, a similarity comparison can be performed, and the response information (similarity, the sequence number of the BC data packet that is the trigger for calculating the similarity, and the location inference target node address) containing the larger similarity can be stored in the response field of the BC data packet to be sent next and then sent.

[0164] In addition, regarding the timing of sending a broadcast data packet with a similarity score recorded in the response field, it can be sent each time the similarities from other nodes are received and compared, or it can also be sent in accordance with a specified order when its own sending order arrives.

[0165] For example, in Figure 10A and Figure 10B 's example, the similarity of the wireless terminal 104, "0.8", is the highest. Therefore, the wireless terminal 101 determines that the wireless terminal 105 is located near the wireless terminal 104.

[0166] Similar to the processing of the wireless terminal 101 in step S5017a, in steps S5017b to S5017e, the wireless terminals 102 to 105 determine that the wireless terminal 105 is located near the wireless terminal that calculates the maximum similarity.

[0167] In addition, the sequence number of the BC data packet that is the trigger for calculating the similarity described in steps S5013 to S5016 is used to make the following distinction, that is, to distinguish which fingerprint among the fingerprints sent by the wireless terminal 105 using the query field is used to calculate the similarity.

[0168] In addition, in the BC data packet sent through step S5011, the address of the wireless terminal 105 as the location inference target can also be included in an area other than the source address.

[0169] In addition, the sending order of the BC data packet can be a specified order or a random order.

[0170] As described above, the control unit 12 of the wireless terminal 101 calculates a first similarity between the fingerprint FP1 measured by the wireless terminal 101 at the first timing and the fingerprint FP5 measured by the wireless terminal 105 at the second timing and transmitted from the wireless terminal 105. The wireless communication unit 11 receives from other wireless terminals 102 to 104 second similarities between the fingerprints FP2 to FP4 measured by the other wireless terminals 102 to 104 at the first timing and the fingerprint FP5 of the wireless terminal 105. The control unit 12 determines the position of the wireless terminal 105 based on the comparison result between the first similarity and the second similarity.

[0171] Thus, the position inference system 1, for example, does not require devices such as a server and a gateway for inferring the position of the wireless terminal 105, and can infer the position of the wireless terminal 105 among the wireless terminals 101 to 105, and can infer the position of the wireless terminal 105 at low cost.

[0172] In addition, the wireless terminals 101 to 105 have the same frame structure to infer the position of the wireless terminal 105. Thus, the position inference system 1 can infer the position of the wireless terminal 105 at low cost.

[0173] In addition, sometimes due to changes in the propagation environment or failures of wireless terminals, the positions of the anchor nodes are changed, exchanged, or added. In the position inference system 1, the change, exchange, and addition of the positions of the anchor nodes can be easily performed.

[0174] For example, in the case of adding an anchor node, the added anchor node starts sending BC data packets. Moreover, the added anchor node receives BC data packets from one or more anchor nodes participating in the mesh network and executes Figure 6 the processing of the flowchart. Thus, the position inference system 1 can easily add an anchor node.

[0175] In addition, compared with a system that infers the position of a mobile node by collecting fingerprints in a server, the position inference system 1 does not require prior communication processing such as a network participation request between the added anchor node and the server. In addition, in the position inference system 1, there is no need to perform processing for notifying existing anchor nodes of the additional information of the added anchor node from the server. Thus, the position inference system 1 can easily add an anchor node.

[0176] In addition, in the position inference system 1, even without communicating with a server, as long as communication is possible between the anchor nodes participating in the mesh network, position inference can be performed. Therefore, in the position inference system 1, the degree of freedom in selecting the addition location becomes higher.

[0177] (Variant 1)

[0178] The wireless terminals 101 to 104 store the saved fingerprints in the storage unit in response to operations of the input / output unit of the user, but it is not limited thereto.

[0179] For example, the wireless terminals 101 to 104 may also detect that the user carrying the wireless terminal 105 is nearby through a human perception sensor, and store the saved fingerprints in the storage unit.

[0180] In addition, the input / output unit of the wireless terminal 105 may also receive an operation from the user for storing the saved fingerprint. The wireless terminal 105 may also send a fingerprint save command to the wireless terminals 101 to 104 when the input / output unit receives an operation from the user. The wireless terminals 101 to 104 may also store the saved fingerprints in the storage unit according to the fingerprint save command sent from the wireless terminal 105.

[0181] In addition, the wireless terminal 105 may, for example, also output a specified signal with a short communication distance such as 1 m to 2 m. It may also be that the wireless terminals 101 to 104 store the saved fingerprints in the storage unit when receiving the specified signal from the wireless terminal 105.

[0182] (Modification Example 2)

[0183] The process of comparing the similarities by the wireless terminals 101 to 105 may also be executed when the number of similarities saved in the storage unit reaches a specified number. For example, when the number of similarities saved in the storage units of the wireless terminals 101 to 105 reaches the specified number, the processes of S5017a to S5017e shown in Figure 10B may be executed.

[0184] At this time, each of the wireless terminals among the wireless terminals 101 to 105 may calculate the average value of the similarities in the wireless terminals 101 to 104 respectively and compare the calculated average value of the similarities. In addition, each of the wireless terminals among the wireless terminals 101 to 105 may extract the similarity with the largest value among the specified number of similarities in the wireless terminals 101 to 104 respectively and compare the extracted similarities.

[0185] In addition, the process of comparing the similarities by the wireless terminals may also be executed at a specified period.

[0186] In addition, the wireless terminals 101 to 104 may also execute the transmission of the BC data packet having the similarity saved in the response field each time receiving and comparing the similarities received from other wireless terminals, or may execute the transmission of the BC data packet having the similarity saved in the response field in a specified order among the wireless terminals 101 to 104.

[0187] (Modification Example 3)

[0188] The wireless terminal 105 as a mobile node can also store and save fingerprints in the storage unit. When the wireless terminal 105 stores and saves fingerprints in the storage unit, the addresses of the wireless terminals 101 to 104 located near the wireless terminal 105 can also be saved as options for saving fingerprints.

[0189] Thus, the wireless terminal 105 can save the saved fingerprints of each of the wireless terminals 101 to 104 located near it, respectively.

[0190] In addition, data packets can be sent from the wireless terminals 101 to 104 that issue the fingerprint save command to the wireless terminal 105 to notify the saved fingerprints and addresses of the wireless terminals 101 to 104. Alternatively, the saved fingerprints and addresses of the wireless terminals 101 to 104 can be given as parameters of the fingerprint save command from the input / output unit of the wireless terminal 105.

[0191] When the fingerprint save command is issued, the wireless terminals 101 to 104 store the fingerprints when the wireless terminal 105 is located nearby as saved fingerprints. On the other hand, the wireless terminal 105 stores the saved fingerprints stored when it is present near the wireless terminals 101 to 104 separately for each of the wireless terminals 101 to 104.

[0192] It can also be that in the process of inferring the position of the wireless terminal 105, the similarities of the wireless terminals 101 to 104 whose calculated similarities are closest to the similarity calculated by the wireless terminal 105 are weighted.

[0193] (Modification Example 4)

[0194] In the storage of fingerprints, regarding how long to retain the old RSSI among the previously added RSSIs, a specified time can be set for each node, or it can be input by the user as a parameter at any time.

[0195] (Modification Example 5)

[0196] When updating fingerprints, when the source address that forms a group with the RSSI to be added is already included in the fingerprints, the wireless terminals 101 to 105 can also rewrite it with the newly measured RSSI at any time. In addition, when updating fingerprints, when the source address and destination address that form a group with the RSSI to be added are already included in the fingerprints, the wireless terminals 101 to 105 can also rewrite it with the newly measured RSSI at any time. In addition, the wireless terminals 101 to 105 can store two or more fingerprints using the sequence number recorded in the BC data packet as an identifier.

[0197] (Modification Example 6)

[0198] When the wireless terminals 101 to 105 update fingerprints, they may also receive fingerprints containing an RSSI that is older than the RSSI of the fingerprints stored at that time point.

[0199] Therefore, in addition to storing the source address and RSSI, the wireless terminals 101 to 105 can also store sequence numbers. When updating fingerprints, the wireless terminals 101 to 105 can compare the sequence numbers of the fingerprints stored in the storage unit with the sequence numbers of the newly received fingerprints, and use the newly measured RSSI to update the fingerprints.

[0200] (Variant Example 7)

[0201] When two or more fingerprint save commands are issued, two or more saved fingerprints can be saved in the storage unit. In addition, the saved fingerprints can be rewritten each time a fingerprint save command is issued.

[0202] In addition, for the saved fingerprints, when multiple fingerprint save commands are issued, the average value of the multiple RSSIs for the multiple fingerprint save commands can be calculated, and the average value of the RSSIs can be stored in the storage unit as the saved fingerprint.

[0203] (Variant Example 8)

[0204] It is also possible that when other anchor nodes that are not the nearest node to the mobile node receive a fingerprint save command, the current fingerprint is stored in the saved fingerprint option instead of the nearest node.

[0205] At this time, it is also possible that other anchor nodes that are not the nearest node to the mobile node save the address of the nearest node in the saved fingerprint option. Thus, for the saved fingerprint stored as the saved fingerprint, which anchor node the mobile node is nearest to when the fingerprint is stored can be identified based on the address of the nearest node saved in the option.

[0206] (Variant Example 9)

[0207] As described above, the anchor node and the mobile node respectively compare the similarities calculated at each anchor node. Moreover, the anchor node and the mobile node respectively determine the maximum similarity.

[0208] When sufficiently different similarities have been calculated for all anchor nodes, the position of the nearest anchor to the mobile node can be clearly determined.

[0209] However, due to the presence of masking objects placed everywhere or the coming and going of people, the indoor propagation environment is prone to change. Therefore, the anchor node closest to the mobile node does not necessarily calculate the highest similarity for all fingerprint vectors maintained at different times.

[0210] In addition, in the case where the similarities calculated by different anchor nodes are very close, it is difficult to determine a nearest node.

[0211] Therefore, it may also be that the anchor node calculates the weight for the similarity score calculated by itself and holds the weighted similarity score in the response field of the broadcast data packet to be sent next.

[0212] The anchor node may also hold a history record of the determination results of the nearest N nodes, calculate the probability that it will be determined as the nearest node next, and multiply it with the similarity as the weight.

[0213] The anchor node may also refer to the information on the fixed installation locations of all anchor nodes, and weight the similarity in such a way that the closer its position is to the nearest node determined just before, the greater the weight, and the farther the distance, the smaller the weight.

[0214] Therefore, the anchor node may save the information on the installation locations of all anchor nodes in the storage unit, or may record its own installation position information in the broadcast data packet periodically sent by the node.

[0215] It may also be that the anchor node pre-holds the update history record of the RSSI constituting the fingerprint vector, and if the proportion of the RSSI that has not been updated within a specified time exceeds a predetermined value, it weights in such a way as to reduce its own similarity.

[0216] In the above embodiments, expressions such as “… unit” used for each component may be replaced with other expressions such as “… circuitry”, “… component”, “… device”, “… unit”, or “… module”.

[0217] As described above, the embodiments have been described with reference to the drawings. However, the present invention is not limited to these examples. Those skilled in the art can obviously think of various modification examples or correction examples within the scope described in the claims. It should be understood that these modification examples or correction examples also belong to the technical scope of the present invention. In addition, the components in the above embodiments can be arbitrarily combined without departing from the gist of the present invention.

[0218] The present invention can be implemented by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiments is partially or wholly implemented as an LSI (Large Scale Integration, large-scale integrated circuit) that is an integrated circuit. Each process described in the above embodiments can also be partially or wholly controlled by one LSI or a combination of LSIs. An LSI can be constituted by a single chip, or can be constituted by one chip in a manner including part or all of the functional blocks. An LSI can also include input and output of data. Depending on the degree of integration, an LSI can also be referred to as an "IC (Integrated Circuit)", "system LSI (System LSI)", "super LSI (SuperLSI)", or "ultra LSI (Ultra LSI)".

[0219] The method of integrating circuits is not limited to LSIs, and can also be implemented by dedicated circuits, general-purpose processors, or dedicated processors. Additionally, an FPGA (Field Programmable Gate Array, field programmable gate array) that can be programmed after the manufacture of an LSI, or a reconfigurable processor that can reconfigure the connection or setting of circuit blocks inside an LSI can also be used. The present invention can also be implemented as digital processing or analog processing.

[0220] Furthermore, if, with the progress of semiconductor technology or the derivation of other technologies, an integrated circuit technology that replaces LSIs emerges, of course, such technology can also be used to implement the integration of functional blocks. There is also the possibility of applying biotechnology and the like.

[0221] The present invention can be implemented in all kinds of devices, equipment, and systems with communication functions (collectively referred to as "communication devices"). The communication device may also include a wireless transceiver and processing / control circuitry. The wireless transceiver may also include a receiving section and a transmitting section, or perform the functions of these sections. The wireless transceiver (transmitting section, receiving section) may also include an RF (Radio Frequency) module and one or more antennas. The RF module may also include an amplifier, an RF modulator / demodulator, or devices similar to these. Non-limiting examples of communication devices include: telephones (mobile phones, smart phones, etc.), tablet computers, personal computers (PCs) (laptop computers, desktop computers, notebook computers, etc.), cameras (digital cameras, digital video cameras, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smart watches, tracking devices, etc.), game consoles, e-book readers, remote health / telemedicine (remote healthcare / medical prescription) devices, transportation vehicles or means of transportation with communication functions (automobiles, airplanes, ships, etc.), and combinations of the above various devices.

[0222] The communication device is not limited to portable or mobile devices, and also includes all kinds of devices, equipment, and systems that are not portable or are fixed. For example, it includes: smart home devices (home appliances, lighting devices, smart meters or gauges, control panels, etc.), vending machines, and all other "Things" that can exist on the IoT (Internet of Things) network.

[0223] Communication includes not only data communication through cellular systems, wireless LAN (Local Area Network) systems, communication satellite systems, etc., but also data communication through combinations of these systems.

[0224] In addition, the communication device also includes devices such as a controller or a sensor that is connected or linked to a communication device that executes the communication functions described in the present invention. For example, it includes a controller or a sensor that generates a control signal or a data signal used by the communication device that executes the communication functions of the communication device.

[0225] In addition, the communication device includes infrastructure devices that communicate with or control the above non-limiting various devices, such as base stations, access points, and all other devices, equipment, and systems.

[0226] (Summary of the present invention)

[0227] The method for inferring the position in the fixed wireless device of the present invention is a method for inferring the position in the fixed wireless device, which includes the following steps: calculating a first similarity between a first fingerprint measured by the fixed wireless device at a first timing and a second fingerprint measured by the mobile wireless device at a second timing and sent from the mobile wireless device; receiving a second similarity between a third fingerprint measured by the other fixed wireless device at the first timing and the second fingerprint from the other fixed wireless device; and determining the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

[0228] In the method for inferring the position of the present invention, when the distance between the mobile wireless device and the fixed wireless device is closer than the distance between the mobile wireless device and the other fixed wireless device, the fixed wireless device stores the first fingerprint at the first timing. When the distance between the mobile wireless device and the other fixed wireless device is closer than the distance between the mobile wireless device and the fixed wireless device, the other fixed wireless device stores the third fingerprint at the first timing.

[0229] In the method for inferring the position of the present invention, the first timing is determined according to a signal output from an input / output circuit provided in the fixed wireless device, and the fixed wireless device measures and stores the first fingerprint at the first timing.

[0230] In the method for inferring the position of the present invention, the first timing is determined according to a signal sent from the mobile wireless device, and the fixed wireless device measures and stores the first fingerprint at the first timing.

[0231] In the method for inferring the position of the present invention, the fixed wireless device sends the first similarity to the other fixed wireless device.

[0232] In the method for inferring the position of the present invention, when the first similarity calculated by the fixed wireless device is a higher similarity than the second similarity received from the other fixed wireless device, it is determined that the distance between the mobile wireless device and the fixed wireless device is closer than the distance between the mobile wireless device and the other fixed wireless device.

[0233] The position inference program of the present invention causes a fixed wireless device to perform the following processes: measuring a first fingerprint at a first timing and storing it; calculating a first similarity between the first fingerprint and a second fingerprint measured by the mobile wireless device at a second timing and transmitted from the mobile wireless device; receiving, from other fixed wireless devices, a second similarity between a third fingerprint measured and stored by the other fixed wireless devices at the first timing and the second fingerprint; and determining the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

[0234] The fixed wireless device of the present invention includes: a control circuit that calculates a first similarity between a first fingerprint measured by the fixed wireless device at a first timing and a second fingerprint measured by the mobile wireless device at a second timing and transmitted from the mobile wireless device; and a communication circuit that receives, from other fixed wireless devices, a second similarity between a third fingerprint measured by the other fixed wireless devices at the first timing and the second fingerprint, and the control circuit determines the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

[0235] The position inference method in the mobile wireless device of the present invention includes the following steps: transmitting a second fingerprint measured by the mobile wireless device at a second timing to a plurality of fixed wireless devices; receiving, from the plurality of fixed wireless devices, a plurality of similarities between a plurality of fourth fingerprints measured by the plurality of fixed wireless devices at a first timing and the second fingerprint; and determining the position of the mobile wireless device based on the plurality of similarities.

[0236] The position inference program of the present invention causes the mobile wireless device to perform the following processes: transmitting a second fingerprint measured by the mobile wireless device at a second timing to a plurality of fixed wireless devices; receiving, from the plurality of fixed wireless devices, a plurality of similarities between a plurality of fourth fingerprints measured by the plurality of fixed wireless devices at a first timing and the second fingerprint; and determining the position of the mobile wireless device based on the plurality of similarities.

[0237] The mobile wireless device of the present invention includes: a transmission circuit that transmits a second fingerprint measured by the mobile wireless device at a second timing to a plurality of fixed wireless devices; a reception circuit that receives, from the plurality of fixed wireless devices, a plurality of similarities between a plurality of fourth fingerprints measured by the plurality of fixed wireless devices at a first timing and the second fingerprint; and a control circuit that determines the position of the mobile wireless device based on the plurality of similarities.

[0238] The entire disclosure of the specification, drawings, and abstract included in Japanese Patent Application No. 2019-228065 filed on December 18, 2019 is incorporated herein by reference.

[0239] Industrial Applicability

[0240] The present invention can be used in a fingerprint position inference system using wireless communication.

[0241] Explanation of Reference Numerals

[0242] 1 Position inference system

[0243] 11 Wireless communication unit

[0244] 12 Control unit

[0245] 13 Input / output unit

[0246] 14 Storage unit

[0247] 50 Data packet

[0248] 101 - 105 Wireless terminals

[0249] 501 Destination address

[0250] 502 Source address

[0251] 504 Sequence number

[0252] 505 Query field

[0253] 506 Response field

[0254] 600 Fingerprint

[0255] 700 Saved fingerprint

Claims

1. A position inference method, which is a position inference method in a fixed wireless device, and the position inference method comprises the following steps: calculating a first similarity between a first fingerprint measured by the fixed wireless device at a first timing, between the fixed wireless device and other fixed wireless devices and a mobile wireless device, and a second fingerprint measured by the mobile wireless device at a second timing, between the mobile wireless device and the fixed wireless device and the other fixed wireless devices, and sent from the mobile wireless device; receiving, from the other fixed wireless devices, a second similarity between a third fingerprint measured by the other fixed wireless devices at the first timing, between the fixed wireless devices other than the device itself and the mobile wireless device, and the second fingerprint; and determining the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

2. The position inference method according to claim 1, wherein when the distance between the mobile wireless device and the fixed wireless device is closer than the distance between the mobile wireless device and the other fixed wireless devices, the fixed wireless device stores the first fingerprint at the first timing, when the distance between the mobile wireless device and the other fixed wireless devices is closer than the distance between the mobile wireless device and the fixed wireless device, the other fixed wireless devices store the third fingerprint at the first timing.

3. The position inference method according to claim 1, wherein the first timing is determined according to a signal output from an input / output circuit provided in the fixed wireless device, and the fixed wireless device measures and stores the first fingerprint at the first timing.

4. The position inference method according to claim 1, wherein the first timing is determined according to a signal sent from the mobile wireless device, and the fixed wireless device measures and stores the first fingerprint at the first timing.

5. The position inference method according to claim 1, wherein the fixed wireless device sends the first similarity to the other fixed wireless devices.

6. The position inference method according to claim 1, wherein when the first similarity calculated by the fixed wireless device is a similarity higher than the second similarity received from the other fixed wireless devices, it is determined that the distance between the mobile wireless device and the fixed wireless device is closer than the distance between the mobile wireless device and the other fixed wireless devices.

7. A computer-readable storage medium storing a position inference program, which, when executed by a processor, causes a fixed wireless device to perform the following processing: measuring and storing a first fingerprint at a first timing, where the first fingerprint is a first fingerprint measured by the fixed wireless device between other fixed wireless devices and a mobile wireless device; calculating a first similarity between the first fingerprint and a second fingerprint measured by the mobile wireless device at a second timing, between the mobile wireless device and the fixed wireless device and the other fixed wireless devices, and sent from the mobile wireless device; Receiving, from the other fixed wireless device, a second similarity between a third fingerprint and the second fingerprint, which are measured by the other fixed wireless device at the first timing and are between a fixed wireless device other than this device and the mobile wireless device; and Determining the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

8. A fixed wireless device, comprising: A control circuit that calculates a first similarity between a first fingerprint, which is measured by the fixed wireless device at a first timing and is between the fixed wireless device and other fixed wireless devices and a mobile wireless device, and a second fingerprint, which is measured by the mobile wireless device at a second timing and is between the mobile wireless device and the fixed wireless device and the other fixed wireless devices, and is sent from the mobile wireless device; and A communication circuit that receives, from the other fixed wireless device, a second similarity between a third fingerprint and the second fingerprint, which are measured by the other fixed wireless device at the first timing and are between a fixed wireless device other than this device and the mobile wireless device, wherein the control circuit determines the position of the mobile wireless device based on a comparison result between the first similarity and the second similarity.

9. A position inference method, which is a position inference method in a mobile wireless device, and the position inference method includes the following steps: Sending, to the plurality of fixed wireless devices, second fingerprints, which are measured by the mobile wireless device at a second timing and are between the mobile wireless device and each of the plurality of fixed wireless devices; Receiving, from the plurality of fixed wireless devices, a plurality of similarities between a plurality of fourth fingerprints and the second fingerprints, which are measured by each of the plurality of fixed wireless devices at a first timing and are between other fixed wireless devices among the plurality of fixed wireless devices and the mobile wireless device; and And Determining the position of the mobile wireless device based on the plurality of similarities.

10. A computer-readable storage medium storing a position inference program, which, when executed by a processor, causes a mobile wireless device to perform the following processing: Sending, to the plurality of fixed wireless devices, second fingerprints, which are measured by the mobile wireless device at a second timing and are between the mobile wireless device and each of the plurality of fixed wireless devices; Receiving, from the plurality of fixed wireless devices, a plurality of similarities between a plurality of fourth fingerprints and the second fingerprints, which are measured by each of the plurality of fixed wireless devices at a first timing and are between other fixed wireless devices among the plurality of fixed wireless devices and the mobile wireless device; and Determining the position of the mobile wireless device based on the plurality of similarities.

11. A mobile wireless device, comprising: A sending circuit that sends, to the plurality of fixed wireless devices, second fingerprints, which are measured by the mobile wireless device at a second timing and are between the mobile wireless device and each of the plurality of fixed wireless devices; A receiving circuit that receives, from the plurality of fixed wireless devices, a plurality of similarities between a plurality of fourth fingerprints and the second fingerprints, which are measured by each of the plurality of fixed wireless devices at a first timing and are between other fixed wireless devices among the plurality of fixed wireless devices and the mobile wireless device; and And A control circuit determines the position of the mobile wireless device based on the plurality of similarities.

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